materials, their properties and uses

unless a phosphate is added. Many industrial cleansers, therefore,may be balanced combinations of soaps, synthetic detergents, phos-phates, or alkalies, designed for particular purposes.

About half of all soap is made with tallow, 25% with coconut oil,and the remainder with palm oil, greases, fish oils, olive oil, soybeanoil, or mixtures. A typical soap contains 80% mixed oils and 20coconut oil, with not over 0.2 free alkali. Auxiliary ingredients areused in soap to improve the color, for perfuming, as an astringent, orfor abrasive or harsh cleaning purposes. Phenol or cresylic acid com-pounds are used in antiseptic soap. The soft soaps and liquid soapsof USP grade have a therapeutic value and may be sold under tradenames.

Solvents are added to industrial soaps for scouring textiles or whenused in soluble oils in the metal industry. Zinc oxide, benzoic acid, andother materials are used in facial soaps with the idea of aiding com-plexion. Excessive alkalinity in soaps dries and irritates the skin, buthand grit soap usually has 2 to 5% alkaline salts such as borax orsoda ash and 10 to 25% abrasive materials. Softer hand soap maycontain marble flour. Silicate of soda, used as a filler, also irritates theskin. Face soaps, or toilet soaps, contain coloring agents, stabilizers,and perfuming agents. For special purposes, cosmetic soaps containmedications. Deodorant soaps contain antibacterial chemicals, suchas triclosan, which inhibit the production of bacteria on the skin.Experts disagree on whether antibacterial ingredients are harmful tothe skin. Some, such as Dove, are a blend of detergents and soap.Castile soap is a semitransparent soap made with olive oil.Marseilles soap and Venetian soap are names for castile soap witholive oil and soda. Ordinary soft soaps used as bases for toilet soap aremade with mixtures of linseed oil and olive oil. Linseed oil, however,gives a disagreeable odor. Soybean oil, corn oil, and peanut oil are alsoused, although peanut oil, unless the arachidic acid is removed, makesa hard soap. Tall oil soaps are sodium soaps made from the fattyacids of tall oil. They are inferior to sodium oleate in detergency, butsuperior to sodium rosinate. Many toilet soaps contain excessunsaponified oil, fatty acid, or lanolin and are known as superfatted.

Saddle soap is any soap used for cleaning leather goods which hasthe property of filling and smoothing the leather as well as cleaning.The original saddle soaps were made of palm oil, rosin, and lye, withglycerin and beeswax added. Oils for the best soaps are of the nondry-ing type. High-grade soft soap for industrial use is made withcoconut or palm kernel oil with caustic potash. But soft soap in pasteform is generally made of low-titer oils with caustic soda, usually lin-seed, soybean, or corn oil. The lauric acid of coconut oil gives thecoconut-oil soaps their characteristic of profuse lathering, but lauric

SOAP 865

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Materials, Their Properties and Uses

acid affects some skins by causing itching, and soaps with highcoconut-oil content and low titer are also likely to break down in hotwater and wash ineffectively. Palm-kernel oil develops free acids, andupon aging the soap acquires the odor of the oil. Palm oil produces acrumbly soap. It does not lather freely, but is mild to the skin. Oliveoil is slow-lathering, but has good cleansing powers. It is often used intextile soaps. Cottonseed oil is used in some laundry soaps, but devel-ops yellow spots in the soap. Corn oil with potash makes a mild softsoap. Soybean oil also makes a soft soap. Rosin is used to make yellowlaundry soaps. ASTM standards for bar soap permit up to 25% rosin.Sulfonated oils do not give as good cleansing action as straight oils,but are used in shampoos where it is desirable to have some oil orgreasiness. Blending of various oils is necessary to obtain a balance ofdesired characteristics in a soap. Hand soaps may be made withtrisodium phosphate or with disodium phosphate, or sodium perbo-rate, NaBO3 H2O, known as perborin, all of which are crystallinesubstances which are dissolved in water solution. Soap powder isgranular soap made in a vacuum chamber or by other specialprocesses. It usually contains 15 to 20% soap and the balance sodiumcarbonate. Scouring powder is an intimate mixture of soap powderand an insoluble abrasive such as pumice. Floating soaps are madelight by blowing air through them while in the vats. Soapless sham-poos and tooth powders contain saponin or chemical detergents.Liquid soaps are made by saponification with potassium and ammo-nium hydroxide, or triethanolamine, to produce more-soluble prod-ucts. The floating soaps, such as Ivory from Procter & Gamble Co.,are made by injecting air into the molten soap.

SOAPSTONE. A massive variety of impure talc employed for elec-tric panels, gas-jet trips, stove linings, tank linings, and as an abra-sive. It can be cut easily and becomes very hard when heatedbecause of the loss of its combined water. The waste product fromthe cutting of soapstone is ground and used for the same purposesas talc powder. Steatite is a massive stone rich in talc that can becut readily, while soapstone may be low in talc. When free of ironoxide and other impurities, block steatite is used for making spacerinsulators for electronic tubes and for special electrical insulators.Block steatite suitable for electrical insulation is mined inMontana, India, and Sardinia. Steatite is also ground and moldedinto insulators. It can be purified of iron and other metallic impuri-ties by electrolytic osmosis. When fluxed with alkaline earthsinstead of feldspar, the molded steatite ceramics have a low lossfactor at high frequencies, and have good electrical properties athigh temperatures. The white-burning refractory steatite of the

866 SOAPSTONE




Red Sea coast of Egypt averages 60% silica and 30.5 magnesia, with1 iron oxide and 1.5 CaO.

Alberene stone, quarried in Virginia, is blue-gray. The medium-hard varieties are used for building trim and for chemical laboratorytables and sinks, and the hard varieties are employed for stair treadsand flooring. Alberene stone marketed by the Alberene Stone Corp. asa basic refractory substitute for chrome or magnesite for mediumtemperatures has a fusion point of 2400°F (1316°C). Virginia green-stone is a gray-green soapstone resistant to weathering, used as abuilding stone. Talc crayons for marking steel are sticks of soap-stone.

SODA ASH. The common name for anhydrous sodium carbonate,Na2CO3, which is the most important industrial alkali. It is a grayish-white, lumpy material which loses any water of crystallization whenheated. For household use in hydrous crystallized form, Na2CO3 10H2O, it is called washing soda, soda crystals, or sal soda, asdistinct from baking soda, which is sodium hydrogen carbonate,or sodium bicarbonate, NaHCO3. Sal soda contains more than 60%water. Another grade, with one molecule of water, Na2CO3 H2O, isthe standard product for scouring solutions. Federal specificationscall for this product to have a total alkalinity not less than 49.7%Na2O. Commercial high-quality soda ash contains 99% minimumNa2CO3, or 58 minimum Na2O. It varies in size of particle and in bulkdensity, being marketed as extra-light, light, and dense. The extra-light has a density of 23 lb/ft3 (368 kg/m3) and the dense has a densityof 63 lb/ft3 (1,009 kg/m3). Laundry soda is soda ash mixed withsodium bicarbonate, with 39 to 43% Na2O. Modified sodas, used forcleansing where a mild detergent is required, are mixtures of sodiumcarbonate and sodium bicarbonate. They are used in both industrialand household cleaners. Tanners’ alkali, used in processing fineleathers, and textile soda, used in fine wool and cotton textiles, aremodified sodas. Flour bland, used by the milling industry in makingfree-flowing, self-raising food flours, is a mixture of sodium bicarbon-ate and tricalcium phosphate.

Soda ash is made by the Solvay process, which consists of treating asolution of common salt with ammonia and with carbon dioxide andcalcining the resulting filter cake of sodium bicarbonate to make lightsoda ash. Dense soda ash is then made by adding water and recal-cining. Soda ash is less expensive than caustic soda and is used forcleansing, for softening water, in glass as a flux and to prevent fog-ging, in the wood-pulp industry, for refining oils, in soapmaking, andfor the treating of ores. Caustic ash, a strong cleaner for metal scour-ing and for paint removal, is a mixture of about 70% caustic soda and

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30 soda ash. Flake alkali, of PPG Industries, contains 71% causticsoda and 29 soda ash. Soda ash is also used as a flux in melting iron toincrease the fluxing action of the limestone, as it will carry off 11% sul-fur in the slag. Soda briquettes, used for desulfurizing iron, aremade of soda ash formed into pellets with a hydrocarbon bond.Hennig purifier is soda ash combined with other steel-purifyingagents made into pellets.

The natural hydrous sodium carbonate of Egypt and Libya is callednitron. Natural soda ash is obtained in Wyoming from beds 5 to 10 ft(1.5 to 3.0 m) thick located 1,200 ft (366 m) underground, which con-tain 47% Na2CO3 and 36 NaHCO3, designated as trona, Na2CO3 NaHCO3 2H2O. By calcination the excess CO2 is driven off, yieldingsoda ash. The salt brine of Owens Lake, California, is an importantsource of soda ash. The brine, which contains 10.5% Na2CO3 and 2.5sodium borate decahydrate, is concentrated and treated to precip-itate the trona. The Salt Lake area of Utah is a source of trona. Sodaash and sodium carbonate may be sold under trade names. Purite isa sodium carbonate. Tronacarb is an industrial grade, andTronalight, as the name suggests, is a light soda ash. Both productsare made by Kerr-McGee Chemical Corp.

SODIUM. A metallic element, symbol Na and atomic weight 23, occur-ring naturally only in the form of its salts. The most important min-eral containing sodium is the chloride, NaCl, which is common salt. Italso occurs as the nitrate, Chile saltpeter, as a borate in borax, and asa fluoride and a sulfate. When pure, sodium is silvery white and duc-tile, and it melts at 208°F (97.8°C) and boils at 1620°F (882°C). Thespecific gravity is 0.97. It can be obtained in metallic form by the elec-trolysis of salt. When exposed to the air, it oxidizes rapidly, and itmust therefore be kept in airtight containers. It has a high affinity foroxygen, and it decomposes water violently. It also combines directlywith the halogens, and is a good reducing agent for the metal chlo-rides. Sodium is one of the best conductors of electricity and heat. Theelement has five isotopes, and sodium 24, made by neutron irradia-tion of ordinary sodium, is radioactive. It has a half-life of 15 h anddecays to stable magnesium 24 with the emission of one beta parti-cle and two gamma rays per atom.

The metal is a powerful desulfurizer of iron and steel even in com-bination. For this purpose it may be used in the form of soda-ashpellets or in alloys. Desulfurizing alloys for brasses and bronzesare sodium-tin, with 95% tin and 5 sodium, or sodium-copper.Sodium-lead, used for adding sodium to alloys, contains 10% sodiumand is marketed as small, spheroidal shot. It is also marketed assodium marbles, which are spheres of pure sodium up to 1 in (2.54

868 SODIUM




cm) in diameter coated with oil to reduce handling hazards. Sodiumbricks contain 50% sodium metal powder dispersed in a paraffinbinder. They can be handled in air and are a source of active sodium.Sodium in combination with potassium is used as a heat-exchangefluid in reactors and high-temperature processing equipment. A sodium-potassium alloy, containing 56% sodium and 44 potas-sium, has a melting point of 66°F (19°C) and a boiling point of 1517°F(825°C). It is a silvery, mobile liquid. High-surface sodium issodium metal absorbed on common salt, alumina, or activated carbonto give a large surface area for use in the reduction of metals or inhydrocarbon refining. Common salt will adsorb up to 10% of itsweight of sodium in a thin film on its surface, and this sodium is100% available for chemical reaction. It is used in reducing titaniumtetrachloride to titanium metal. Sodium vapor is used in electriclamps. When the vapor is used with a fused alumina tube, it gives agolden-white color. A 400-W lamp produces 42,000 lm and retains85% of its efficiency after 6,000 h.

Sodium compounds are widely used in industry, particularlysodium chloride, sodium hydroxide, and soda ash. Sodium bichro-mate, Na2Cr2O7 2H2O, a red, crystalline powder, is used in leathertanning, textile dyeing, wood preservation, and pigments. Whenheated, it changes to the anhydrous form which melts at 673°F(356°C) and decomposes at about 752°F (400°C). In a hot water solu-tion with sulfuric acid, sodium bichromate gives a golden-brown,brasslike finish to zinc parts. The sodium bichromate liquor fromalkali production is used for making pigments. When combined withlead compounds, the bichromate precipitate is yellow. The addition ofiron blue, or ferric cyanide, develops greens. Sodium metavan-date, NaVO3, is used as a corrosion inhibitor to protect some chemi-cal-processing piping. It dissolves in hot water, and a small amount inthe water forms a tough, impervious coating of magnetic iron oxide onthe walls of the pipe. Sodium iodide crystals are used as scintilla-tion probes for the detection and analysis of nuclear energies.Sodium oxalate is used as an antienzyme to retard tooth decay. Inthe drug industry, sodium is used to compound with pharmaceuticalsto make them water-soluble salts. Gas-generating pellets or wafers ofsodium azide are used as a propellant in auto airbag inflators. Uponignition, the gas burns and liberates large amounts of nitrogen gas,inflating the bag. Sodium is a plentiful element, easily available, andis one of the most widely used.

SODIUM CYANIDE. A salt of hydrocyanic acid of composition NaCN,used for carbonizing steel for case hardening, for heat-treatingbaths, for electroplating, and for the extraction of gold and silver

SODIUM CYANIDE 869




from their ores. For carburizing steel it is preferred to potassiumcyanide because of its lower cost and its higher content of availablecarbon. It contains 53% CN, as compared with 40% in potassiumcyanide. The nitrogen also aids in forming the hard case on thesteel. The 30% grade of sodium cyanide, melting at 1156°F (679°C),is used for heat-treating baths instead of lead, but it forms a slightcase on the steel. Sodium cyanide is very unstable, and on exposureto moist air it liberates the highly poisonous hydrocyanic acidgas, HCN. For gold and silver extraction it easily combines with themetals, forming soluble double salts, NaAu(CN)2. Sodium cyanide ismade by passing a stream of nitrogen gas over a hot mixture ofsodium carbonate and carbon in the presence of a catalyst. It is awhite, crystalline powder, soluble in water. The white coppercyanide used in electroplating has composition Cu2(CN)2, contain-ing 70% copper. It melts at 887°F (475°C) and is insoluble in water,but is soluble in sodium cyanide solution. Sodium ferrocyanide,or yellow prussiate of soda, is a lemon-yellow, crystalline solid ofcomposition Na4Fe(CN)6 10H2O, used for carbonizing steel for casehardening. It is also employed in paints, in printing inks, and forthe purification of organic acids; in minute quantities, it is used insalt to make it free-flowing. It is soluble in water. Calciumcyanide in powder or granulated forms is used as an insecticide. Itliberates 25% of hydrocyanic acid gas. Cyanogas, of AmericanCyanamid Co., is gaseous HCN from calcium cyanide.

SODIUM HYDROXIDE. Known commonly as caustic soda, and also assodium hydrate. Lye is an old name used in some industries and inhousehold uses. It is a white, massive, crystalline solid of compositionNaOH used for scouring and cleaning baths, for etching aluminum, inquenching baths for heat-treating steel, in cutting and soluble oils, inmaking soaps, and in a wide variety of other applications. It is usu-ally a by-product in the production of chlorine from salt. The specificgravity is 2.13 and melting point 604°F (318°C). It is soluble in water,alcohol, and glycerin. Sodium hydroxide is sold in liquid and in solidor powder forms on the basis of its Na2O content. A high-grade com-mercial caustic soda contains 98% minimum NaOH equivalent to 76minimum Na2O. The liquid contains 50% minimum NaOH. Pels, ofPPG Industries, is a caustic soda in bead form. It is less irritating tothe skin when used in detergents. Phosflake, of PPG Industries,used in washing machines, is a mixture of caustic soda and trisodiumphosphate. Caustic potash is potassium hydroxide, KOH, whichhas the same uses but is more expensive. Caustic potash is a white,lumpy solid. It is soluble in water and makes a powerful cleansingbath for scouring metals. It is marketed as solid, flake, granular, or

870 SODIUM HYDROXIDE




broken, and also is 40 to 50% liquid solutions. It is used in soaps andfor bleaching textiles. When used in steel-quenching baths, it gives ahigher quenching rate than water alone and does not corrode thesteel as a salt solution does.

SODIUM NITRATE. Also called soda niter and Chile saltpeter.A mineral found in large quantities in the arid regions of Chile,Argentina, and Bolivia, where the crude nitrate with iodine and otherimpurities is called caliche. It is used for making nitric and sulfuricacids, for explosives, as a flux in welding, and as a fertilizer. The com-position is NaNO3. It is usually of massive, granular, crystallinestructure with a Mohs hardness of 1.5 to 2 and specific gravity of2.29. It is colorless to white, but sometimes colored by impurities. It isreadily soluble in water. In other parts of the world it occurs in bedswith common salt, borax, and gypsum. Sodium nitrate is also madeby nitrogen fixation and is marketed granulated, in crystals, or insticks. It is colorless and odorless, and it has a specific gravity of2.267 and a melting point of 601°F (316°C). It has a bitter, salinetaste. Sodan, used for spraying on soils, is a clear liquid solution ofsodium nitrate and ammonium nitrate containing 20% nitrogen.Norway saltpeter, used in fertilizers and explosives, is calciumnitrate, Ca(NO3)2, in colorless crystals soluble in water. Calciumnitrate of fine crystal size is used as a coagulant for rubber latex.

SODIUM SILICATE. A water-soluble salt commonly known as waterglass or soluble glass. Chemically, it is sodium metasilicate ofcomposition Na2SiO3 or NaSiO3 9H2O. Two other forms of the silicateare also available, sodium sequisilicate, 3Na2O 2SiO2, and sodiumorthosilicate, 2Na2O SiO2. All of these are noted for their powerfuldetergent and emulsifying properties and for their suspending power.The material has good adhesion, and large quantities are used inwater solutions for industrial adhesives. It is also used to inhibit cor-rosion in potable- and industrial-water systems, forming an oxidation-resistant film on pipe walls. If corrosion has begun, pH-neutral reconditioning solutions can remove the rust or scale with-out pH adjustment of flush water. When solid, sodium silicate is glassyin appearance and dissolves in hot water. It melts at 1864°F(1018°C).It is obtained by melting sodium carbonate with silica, or by meltingsand, charcoal, and soda. The fused product is ground and dissolved inwater by long boiling. Potassium silicate is made in the same way, ora complex soluble glass is made by using both sodium and potassiumcarbonates. Potassium silicate is more soluble than sodium silicate.Kasil, of Philadelphia Quartz Co., is a potassium silicate in fine pow-der containing 71% SiO2 and 28.4 K2O. It is used in ceramic coatings

SODIUM SILICATE 871




and refractory cements. Corlok is potassium silicate free of fluoridesand sodium compounds. It is resistant to strong oxidizing acids, hasgood bond strength, and is used as a cement for acid tanks.Ammonium silicate has an ammonium group instead of the sodium.Quram 220, of Philadelphia Quartz Co., is this material in the formof white powder or in opalescent solution. The intermediate silicagrades act like sodium silicates and are used as binders for refractoryceramics.

Sodium silicate is marketed as a viscous liquid or in powder form.It is used as a detergent, as a protection for wood and porous stone, asa fixing agent for pigments, for cementing stoneware, for lute cementsfor such uses as sealing lightbulbs, for waterproofing walls, forgreaseproofing paper containers, for coating welding rods, as a fillerfor soaps, and as a catalyst for high-octane gasoline. It increases thecleansing power of soaps but irritates the skin. However, it is used incleansing compounds because it is a powerful detergent. Brite Sil isa spray-dried sodium silicate powder which dissolves more easily andmore uniformly.

Sodium silicate is also used for insulating electric wire. It is appliedin solution, and the coated wire is then heated, leaving a flexible coat-ing. Mixed with whiting, it is used as a strong cement for grindingwheels. Sodium metasilicate marketed by Philadelphia Quartz Co. asa cleaner of metals is a crystalline powder. Hot solutions of this saltin water are caustic and will clean grease readily from metals.Drymet is the anhydrous sodium metasilicate. It is a fine, white pow-der with total alkalinity of 51% Na2O. It is easily soluble in water andis used as a detergent in soap powders to give free-flowing, noncakingproperties. The anhydrous material for a given detergent strengthweighs little more than half the weight of the hydrous powder.Dryorth is the anhydrous material of 60% alkalinity. It is a powerfuldetergent and grease remover. Crystamet is the material with 42%water of crystallization. It is a free-flowing white powder. Penchloris an acidproof cement made by mixing cement powder with asodium silicate solution. It is used for lining chemical tanks anddrains. Aquagel, of Silica Products Co., is a hydrous silicate of alu-mina, used in the same manner for waterproofing concrete.

SOLDER. An alloy of two or more metals used for joining other met-als together by surface adhesion without melting the base metals asin welding and without requiring as high a temperature as in braz-ing. However, there is often no definite temperature line between sol-dering alloys and brazing alloys. A requirement for a true solder isthat it have a lower melting point than the metals being joined andan affinity for, or be capable of uniting with, the metals to be joined.

872 SOLDER




A common solder is called half-and-half, or plumbers’ solder,and is composed of equal parts of lead and tin. It melts at 360°F(182°C). The density is 0.318 lb/in3 (8,802 kg/m3), the tensile strengthis 5,500 lb/in2 (38 MPa), and the electrical conductivity is 11% that ofcopper. SAE solder No. 1 has 49.5 to 50.0% tin, 50 lead, 0.12 maxi-mum antimony, and 0.08 maximum copper. It melts at 359°F (181°C).Much commercial half-and-half, however, usually contains larger pro-portions of lead and some antimony, with less tin. These mixtureshave higher melting points, and solders with less than 50% tin have awide melting range and do not solidify quickly. Sometimes a widemelting range is desired, in which case a wiping solder with 38 to45% tin is used. A narrow-melting-range solder, melting at 362 to365°F (183 to 185°C), contains 60% tin and 40 lead. A 42% tin and 58lead solder has a melting range of 362 to 448°F (183 to 231°C).Slicker solder is the best quality of plumbers’ solder, containing 63to 66% tin and the balance lead. The earliest solders were the Romansolders called argentarium, containing equal parts of tin and lead,and tertiarium, containing 1 part tin and 2 lead. Both alloys are stillin use, and throughout early industrial times tertiarium was knownas tinman’s solder.

Good-quality solders for electrical joints should have at least 40%tin, as the electrical conductivity of lead is only about half that oftin, but conductivity is frequently sacrificed for better wiping ability,and the wiping solders are usually employed for electrical work.Soft solders should not contain zinc because of poor adhesion fromthe formation of oxides. Various melting points to suit the work areobtained with solders by varying the proportions of the metals. Thelow-melting solders are those that melt at 446°F (230°C) or lower,and the high-melting solders melt at higher temperatures. Theflow point, at which the solder is entirely liquid, is often consider-ably above the melting point. Tin added to lead lowers the meltingpoint of the lead until, at 356°F (180°C), at 68% tin, the meltingpoint rises as the tin content increases until the melting point ofpure tin is reached. A standard solder with 48% tin and 52 leadmelts at 360°F (182°C). A 45–55 solder melts at 440°F (227°C). Cheapsolders may contain much less tin, but they have less adhesion. SAEsolder No. 4 contains 22.5 to 23.5% tin, 75 lead, and 2 maximumantimony. It melts at 370°F (188°C).

A tin-silver-copper alloy, developed at the University of Iowa (Ames),is lead-free and intended to replace tin-lead solders. Made by blendingspherical powder particles with a fluxing agent, the lead-free soldermelts at 421°F (216°C) and wets similarly to tin-lead solders. The sil-ver and copper form hard, intermetallic phases, reinforcing the tin andstrengthening the solder. The toxicity of lead has been the impetus in

SOLDER 873




the quest for its elimination in solder, especially for printed circuits inthe electronics industry where the 63tin-37lead eutectic alloy hasdominated for many years. Five promising tin-based, lead-free alloysand their eutectic or melting temperatures are: tin-3.5silver (430°F,221°C), tin-3silver-2bismuth (428°F, 220°C), tin-2.6silver-0.8 copper-0.5antimony (412°F, 211°C), tin-3.4silver-4.8bismuth (410°F,210°C) and tin-3.5silver-0.5copper-1zinc (430°F, 221°C). With an ulti-mate tensile strength of about 8,000 lb/in (55 MPa) and a shearstrength of about 4,600 lb/in2 (32 MPa), the tin-3.5 silver alloy isstronger than the tin-37lead alloy; it is also more creep resistant.

Solders with low melting points are obtained from mixtures of lead,tin, cadmium, and bismuth. Bismuth solder is also more fluid, asbismuth lowers surface tension. Bismuth, however, hardens the alloy,although to a lesser extent than antimony. A bismuth solder contain-ing equal parts of lead, tin, and bismuth melts at 284°F (140°C).Cerrolow alloys, of Cerro Metal Products Co., are bismuth solderscontaining sufficient indium to be designated as indium solders.Cerrolow 147, which melts at 142°F (61°C), contains 48% bismuth,25.6 lead, 12.8 tin, 9.6 cadmium, and 4 indium. Cerrolow 105, melt-ing at 100°F (38°C), contains 42.9% bismuth, 21.7 lead, 8 tin, 5 cad-mium, 18.3 indium, and 4 mercury. Cadmium solders have lowmelting points, are hard, and are usually cheaper than tin solders;but they have the disadvantage of blackening and corroding, and thefumes are toxic. Cadmium-zinc solders were used in wartimebecause of the scarcity of tin. A solder containing 80% lead, 10 tin,and 10 cadmium has about the same strength as a 50–50 tin-lead sol-der and has greater ductility, but is darker in color. Cadmium-tinsolder, with high cadmium, is used to solder magnesium alloys. Softsolders for soldering brass and copper, especially for electric connec-tions, may be of tin hardened with antimony. Solder wire for thispurpose contains 95% tin and 5 antimony. Thallium may be used inhigh-lead solders to increase strength and adhesion.

Hard solder may be any solder with a melting point above that ofthe tin-lead solders; more specifically, hard solders are the brazingsolders, silver solders, or aluminum solders. Aluminum solders maycontain up to 15% aluminum. A solder prepared by the NationalBureau of Standards contains 87% tin, 8 zinc, and 5 aluminum. It hasgood strength and ductility. Alcoa solder 805, for joining aluminumto steel or other metals, has 95% zinc and 5 aluminum. The meltingrange is 715 to 725°F (379 to 385°C). For soldering aluminum to alu-minum, an alloy of 91% tin and 9 zinc is used.

The solder known as Richard’s solder is a yellow brass with 3%aluminum and 3 phosphor tin. Solders containing nickel are used forsoldering nickel silver, and silver and gold solders are used for jewelry

874 SOLDER




work. Silver solder in varying proportions is also used as a high-melting-point solder for general work, and small amounts of sil-ver are sometimes used in lead-tin solders to conserve tin, but themelting point is high. Lead-tin solders with more than 90% lead andsome silver, in use during war emergency, had high melting points andpoor spreading qualities. Indium improves these solders, and a solderwith 96% lead, 3 silver, and 1 indium has a melting point of 590°F(310°C) and a tensile strength of 4,970 lb/in2 (34 MPa). Cerroseal 35,of Cerro Metal Products Co., contains 50% tin and 50 indium. It meltsat 240°F (116°C), has low vapor pressure, and will adhere to ceramics.Alkali-resistant solders are indium-lead alloys. A solder with 50%lead and 50 indium melts at 360°F (182°C) and is very resistant toalkalies, but lead-tin solders with as little as 25% indium are resistantto alkaline solutions, have better wetting characteristics, and arestrong. Indium solders are expensive. Adding 0.85% silver to a 40% tinsoft solder gives equivalent wetting on copper alloys to a 63% tin sol-der, but the addition is not effective on low-tin solders. A gold-coppersolder used for making high-vacuum seals and for brazing difficultmetals such as iron-cobalt alloys contains 37.5% gold and 62.5 copper.The silver-palladium solders have high melting points, 2246°F(1232°C) for a 30% palladium alloy, and good flow, and corrosion resis-tance. A palladium-nickel alloy with 40% nickel has a melting pointof about 2258°F (1237°C). The brazing alloys containing palladium areuseful for a wide range of metals and metal-to-ceramic joints.

Cold solder, used for filling cracks in metals, may be a mixture ofa metal powder in a pyroxylin cement with or without a mineral filler,but the strong cold solders are made with synthetic resins, usuallyepoxies, cured with catalysts, and with no solvents to cause shrink-age. The metal content may be as high as 80%. Devcon F, of DevconCorp., for repairing holes in castings, has 80% aluminum powder and20 epoxy resin. It is heat-cured at 150°F (66°C), giving high adhesion.Epoxyn solder is aluminum powder in an epoxy resin in the form ofa putty for filling cracks or holes in sheet metal. It cures with a cata-lyst. The metal-epoxy mixtures give a shrinkage of less than 0.2%,and they can be machined and polished smooth.

SOLVENT. A material, usually a liquid, having the power of dissolv-ing another material and forming a homogeneous mixture called asolution. The mixture is physical, and no chemical action takesplace. A solid solution is such a mixture of two metals, but theactual mixing occurs during the liquid or gaseous state. Some mate-rials are soluble in certain other materials in all proportions, whileothers are soluble only up to a definite percentage and the residueis precipitated out of solution. Homogeneous mixtures of gases may

SOLVENT 875




technically be called solutions, but are generally referred to only asmixtures.

The usual industrial applications of solvents are for putting solidmaterials into liquid solution for more convenient chemical processing,for thinning paints and coatings, and for dissolving away foreign mat-ter as in dry-cleaning textiles. But they may have other uses, such asabsorbing dust on roadways and killing weeds. They have an impor-tant use in separating materials, for example, in the extraction of oilsfrom seeds. In such use, a clathrate is a solid compound added to thesolution containing a difficult-to-extract material, but which is trappedselectively by the clathrate. The solid clathrate is then filtered out andprocessed by heat or chemicals to separate the desired compound.Antifoamers are chemicals, such as the silicones, added to solvents toreduce foam so that processing equipment can be used to capacitywithout spillover. Antifoam 71, of General Electric, is a silicone emul-sion that can be used in foodstuffs in proportions up to 100 parts permillion. Solvent-solvents are solvents used for second-stage extrac-tion of difficult-to-extract metals such as gold, uranium, and thorium.Tributyl phosphine oxide, (C4H9)3PO, a white, crystalline powder,is such a material used in benzene or kerosene solution for extractingmetals from the acids employed in ore extraction.

The usual commercial solvents for organic substances are the alco-hols, ether, benzene, and turpentine, the latter two being common sol-vents for paints and varnishes containing gums and resins. Theso-called coal-tar solvents are light oils from coal tar, distilling offbetween 293 and 356°F (145 and 180°C), with specific gravity 0.850 to0.890. Solvent oils, from coal tar, are amber to dark liquids with dis-tillation ranges from about 302 to 644°F (150 to 340°C), with specificgravity 0.910 to 0.980. They are used as solvents for asphalt var-nishes and bituminous paints. Shingle stains are amber to darkgrades of solvent oils of specific gravity 0.910 to 0.930.

A valuable solvent for rubbers and many other products is carbonbisulfide, CS2, also called carbon disulfide, made by heatingtogether carbon and sulfur. It is flammable and toxic. When pure, it isnearly odorless. The specific gravity is 1.2927 and boiling point 116°F(46.5°C). Ethyl acetate, CH3COOC2H5, made from ethyl alcohol andacetic acid, is an important solvent for nitrocellulose and lacquers. Itis liquid, boiling at 171°F (77°C). Ashland Chemical Co. makes it inthree grades, containing 85 to 88, 99, and 99.5% ethyl acetate. Someproducers offer ethyl acetate solvent grades for urethanes. One of thebest solvents for cellulose is cuprammonium hydroxide. Amyl andother alcohols, amyl acetate, and other volatile liquids are used forquick-drying lacquers, but many synthetic chemicals are available forsuch use. Dioxan, a water-white liquid of specific gravity 1.035 and

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composition CH2CH2OCH2CH2O, is a good solvent for cellulose com-pounds, resins, and varnishes, and is used also in paint removers,which owe their action to their solvent power. Dow Chemical Co.makes a similar material, called diethylene ether. Ferro Corp.’sbrand is an uninhibited variety, 1,4-dioxane, that has a purity of99.97% and comes packed under nitrogen. Ethyl lactate, used as asolvent for cellulose nitrate, is a liquid with boiling point of 150°C andspecific gravity of 1.03. Octyl alcohol, a liquid of compositionCH3(CH2)6CH2OH, specific gravity 1.429, and boiling point of 383°F(195°C), has a high solvent power for nitrocellulose and resins.Diafoam is a secondary octyl alcohol used as a defoaming agent inplastics and lacquers. Methyl hexyl ketone, CH3(CH2)5COCH3, is apowerful, high-boiling-point solvent which also acts as a dispersingagent in inks, dyestuffs, and perfumes. It is a water-white liquid boil-ing at 343°F (173°C). It is made by Penta Manufacturing Co.

The chlorinated hydrocarbons have powerful solvent action onfats, waxes, and oils and are used in degreasing. Of major commer-cial significance are perchloroethylene (PCE), trichloroethyl-ene (TCE), and 1,1,1-trichloroethane (1,1,1-TCA). The biggestindustrial use of PCE, also known as tetrachloroethylene andPerc, is as a dry-cleaning solvent because of its nonflammability,and high solvency, vapor pressure, and stability. The largest applica-tions of TCE and 1,1,1-TCA have been in metal cleaning, which alsoconsumes significant quantities of PCE. Because 1,1,1-TCA has beenimplicated in ozone depletion of the stratosphere, its use is beingdiscontinued. Hydrofluoroether-based solvents have similar boilingpoints to 1,1,1-TCA and CFC-113 and are possible alternatives to1,1,1-TCA. Actrel ED, of Exxon Chemical, is a line of non-ozone-depleting solvents for cleaning electronics. These specially processedhydrocarbons are effective in removing resin residues from printed-circuit boards and other organic and ionic contaminants from elec-tronic components. Water is a solvent for most acids and alkaliesand for many organic and inorganic materials. Acids or alkalies thatdecompose the material are not solvents for the material. Solventsare used to produce a solution that can be applied, as in the case ofpaints, and the evaporation of the solvent then leaves the materialchemically unchanged. They may also be employed to separate onesubstance from another, by the selection of a solvent that dissolvesone substance but not the other. Dichlorethyl ether, a yellowishliquid with a chloroformlike odor, of compositionClCH2CH2OCH2CH2Cl, is a good solvent for fats and greases and isused in scouring solutions and in soaps. Dichlorethylene is a liq-uid of composition C2H2Cl2, specific gravity 1.278, and boiling point

SOLVENT 877




about 126°F (52°C). It is used as a solvent for the extraction of fatsand for rubber.

Dichloromethane, known also as methylene chloride and car-rene, is a colorless, nonflammable liquid of composition CH2Cl2, boil-ing at 104°F (39.8°C). It is soluble in alcohol and is used in paintremovers, as a dewaxing solvent for oils, for degreasing textiles, andas a refrigerant. A low-boiling solvent for oils and waxes is butylchloride, CH3CH2CH2CH2Cl. It is a water-white liquid of specificgravity 0.8875, boiling at 173°F (78.6°C). Isocrotyl chloride is a liq-uid of composition CH3:C(CH2)2 CHCl, with specific gravity 0.919and boiling point 154°F (68°C), used for cleaning and degreasing.Cyclohexane, (CH2)6, made by the hydrogenation of benzene, is agood solvent for rubbers, resins, fats, and waxes. It is a water-white,highly flammable liquid of specific gravity 0.777, boiling point 177°F(80.8°C), and flash point 10°F (12°C). This solvent is marketed inEngland as Sextone. Nadene of Allied-Signal Co. is cyclohexa-none, CH2(CH2)4C O. It is a powerful general solvent, and is used asa coupling agent for immiscible compounds. The Sulfolanes of ShellOil Co. are selective solvents for separating mixtures having differentdegrees of saturation, and they can be removed easily by water wash.Dimethyl sulfolane is produced from pentadiene by reacting withSO2 and hydrogenation. Cyclohexanol, also called hexalin andhexahydrophenol, C6H11OH, is a solvent for oils, gums, waxes, rub-ber, and resins. It is made by the hydrogenation of phenol, and is aliquid, boiling at 316°F (158°C).

Dichlorethyl, CH2(OCH2 CH2 Cl)2, is a water-insoluble high-boiling solvent for cellulose, fats, oils, and resins. The boiling point is424°F (218°C), and specific gravity 1.234. The nitroparaffins consti-tute a group of powerful solvents for oil, fats, waxes, gums, andresins. Blended with alcohols, they are solvents for cellulose acetate,producing good flow and hardening properties for nonblushing lac-quers. Nitromethane, CH3NO2, is a water-white liquid, with specificgravity 1.139, boiling point 214°F (101°C), and freezing point 20°F(29°C). It is also used as a rocket fuel. At 500°F (260°C) it explodesinto a hot mixture of nitrogen, hydrogen, carbon monoxide, carbondioxide, and water vapor, but with a catalyst the disintegration canbe controlled into a smooth, continuous explosion. Nitrofuel is anindustrial grade used in automobile racing and in model engines. It isalso a raw material for chemical synthesis and a stabilizer for halo-genated alkanes. Nitrofuel is made by Angus Chemical Co.Nitroethane, CH3CH2NO2, has a specific gravity 1.052, boiling point237°F (114°C), and freezing point 130°F (90°C).

Because of the ozone depletion potential and health and environ-mental concerns regarding chlorine solvents, various compounds for

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cleaning with aqueous and semiaqueous solvents have come about.NST, a low-temperature polyethylene glycol ether with sodiumpyrophosphate, of Oakite Products Inc., is used for ultrasonic clean-ing of aluminum, copper, and brass parts. Micro, a high-temperaturesulfonated compound with ethylenediamine tetracetic acid, ofInternational Products Corp., is applied in ultrasonic cleaning of ironand steel parts. A blend of Solvent 140, a high-flash-point hydrocar-bon mineral spirit, and 5% dipropylene glycol methyl ether(DPM) is effective in manually cleaning 304L stainless steel. AddingDPM makes the water-immiscible solvent miscible with water,enhancing its ability to displace waterborne machining coolants. Boththe 140 and blend are flammable and slow to evaporate, however,necessitating special precautions. Zestron solvents, of Dr. O. K. WackChemie GmbH of Germany, use propylene glycol ether, have a boil-ing point of about 338°F (170°C), and are used to clean circuit boardsin electronics production. A semiaqueous system of Dow Europe usesmodified propylene glycol ethers for this application. In the UnitedStates, Dow offers semiaqueous solvent Dowanol PX-165, which con-tains polar and nonpolar molecules, is nontoxic and biodegradable,and has no ozone depletion potential. BASF AG of Germany offerssemiaqueous cleaning solvents based on n-methyl pyrrolidine, anonhalogenated solvent with a boiling point of 395°F (201°C) said tobe a suitable alternative to methyl chloroform for degreasing andto methylene chloride for paint stripping.

Oxsol, from Occidental Chemical, combines benzotrifluorides,monochlorotoluene, and perchloroethylene. It is not ozone depletingand seems suitable for various cleaning tasks. Dow Chemical’s Invertsolvents 1000, 2000, and 5000 feature reduced solvent and volatileorganic compounds, and can serve as replacements for many chlori-nated solvents. The 1000 and 5000 are based on aliphatic hydrocar-bons, and the 2000 is turpene-based. Not being boilable, however,they are not suitable for vapor degreasing. Purasolv solvents, fromPurac America, are lactate esters derived from natural lactic acidand alcohols. They are biodegradable, toxicologically and environmen-tally safe, not ozone depleting, and recyclable by vacuum distillationfor reuse in degreasing. They are strong solvents for polar and nonpo-lar substances, leave no residue on drying, and are effective forremoval of high-solids coatings, photoresists, and rosin-containingfluxes. Grades include ML methyl lactate, EL and ELS ethyl lac-tates, and BL butyl lactates, with boiling points of 291 to 372°F (144to 189°C) and flash points of 131 to 174°F (55 to 79°C).

A plasticizer is a liquid or solid that dissolves in or is compatiblewith a resin, gum, or other material and renders it plastic, flexible, oreasy to work. A sufficient quantity of plasticizer will result in a viscous

SOLVENT 879




mixture which consists of a suspension of solid grains of the resin orgum in the liquid plasticizer. The plasticizer is in that sense a solvent, but unlike an ordinary solvent the plasticizer remains withthe cured resin to give added properties to the materials, such as flexi-bility. Dibutyl phthalate, a water-white, oily liquid of specific gravity1.048, boiling point 644°F (340°C), and composition C16H22O4, is aplasticizer for Buna N rubber and polyvinyl chloride plastics.Monoplex DOA, of Rohm & Haas Co., used to give flexibility to vinylresins at low temperatures, is diisooctyl adipate. It has a flash pointof 400°F (204°C) and freezing point of 131°F (55°C). Diiso-nonylphthalate and diisodecyl phthalate are high-molecular-weightplasticizers for flexible polyvinyl chloride. An aprotic solvent is a sol-vent that contains no hydrogen, such as selenium oxychloride, a liq-uid of composition SeOCl2. Such solvents are used in electronicapplications where the energy deflection of free protons would beundesirable. Phosphorus oxychloride, POCl3, is an aprotic solventused with neodymium in liquid lasers to give high light-beam effi-ciency.

SORBITOL. A hexahydric alcohol, (CH2OH)5CHOH, which occursnaturally in many fruits, but is now made on a large scale by thedirect hydrogenation of corn sugar, or dextroglucose. It is a white,odorless, crystalline powder of faint sweet taste. It melts at 208°F(97.7°C) and is easily dissolved in water. It is used as a humectant,softener, and blending agent; for the production of synthetic resins,plasticizers, and drying oils; and as an emulsifier in cosmetics andpharmaceuticals. It is digestible and nutritive and is used in confec-tionery to improve texture and storage life by inhibiting crystalgrowth of the sugar, and in dietary foods as a substitute for sugar.Sorbo and Arlex, of ICI Americas, Inc., are water solutions of sor-bitol. Neosorb is a granular form from Roquette Corp. that is usedfor tabletting drugs. Mannitol is an isomer form of the alcohol and isproduced in granular form for pharmaceuticals and foodstuffs as abinder. In the form of a free-flowing powder, it is used as an anticak-ing agent in pharmaceuticals and foodstuffs where a silica or othermineral-based agent is undesirable. The polysorbates are esters ofsorbitol. Polysorbate 80, of Hodag Chemical Corp., is such a mater-ial used as an emulsifier in prepared mixed food for improving tex-ture and stability. Hex, a metal-cleaning and protective agent, is aphosphoric acid ester of sorbitol.

Sorbitol additives are also used to impart clarity to polypropylenefor packaging food and other products. EC-1, of EC Chemical of Japanand marketed outside Asia by Milliken Chemicals as Millad 3905, isbased on dibenzylide technology. Though it provides excellent odor and

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taste quality, limited clarity and significant plateout (prematurevolatilization in processing) has retarded its use. Gell All MD, of NewJapan Chemical, and Millad 3940, of Milliken, are based on dimethyl-benzylidine technology. They improve clarity and reduce plateout butpose odor and taste problems. Also based on this technology isSchering Polymer Additives’ (United Kingdom) Geniset MD. Itimproves clarity, reduces plateout, and lessens odor and taste prob-lems. NC-4, of Mitsui Toatsu of Japan and based on bis (p-ethylben-zylidene) technology, virtually eliminates plateout, significantlyimproves clarity, and, by removing alkyl impurities, improves odor andtaste. Milliken’s Millad 3988, a sorbitol-acetal additive, also excels interms of clarity, plateout, and odor and taste performance.

SOUND AND VIBRATION INSULATORS. Materials used for reducing thetransmission of noise. Insulators are used to impede the passage ofsound waves, as distinct from isolators used under machines toabsorb the vibrations that cause the sound. For factory use the walls,partitions, and ceilings offer the only media for the installation ofsound insulators. All material substances offer resistance to the pas-sage of sound waves, and even glass windows may be considered asinsulators. But the term refers to the special materials placed in thewalls for this specific purpose. Insulators may consist of mineral wool,hair felt, foamed plastics, fiber sheathing boards, or simple sheathingpapers. Sound insulators are marketed under a variety of tradenames, such as Celotex, made from bagasse, and Fibrofelt, madefrom flax or rye fiber. Wheat straw is also used for making insulatingboard. Sound insulators are often also heat insulators. Linofelt is asound- and heat-insulating material used for walls. It consists of aquilt of flax fiber between tough waterproof paper. It comes in sheets0.3125 to 0.75 in (0.80 to 1.91 cm) thick. Torofoleum is a Germaninsulating material made from peat moss treated with a waterproof-ing agent. It withstands temperatures up to 230°F (110°C), is porous,and has a density of less than 1 lb/ft3 (0.005 kg/m3). Fiber metal, ofTechnetics Corp., comprises randomly interlocked similar metalfibers, with the fibers bonded by sintering at all contact points.Similar to nonwoven textile felts, its trade name is Feltmetal, and itis available in sheet form in various fibers, thickness, and porosity.Stainless steel (316 and 347) and aluminum-alloy fibers are usedmainly for noise reduction of aircraft turbines, turbine blowers, andhigh-speed fans. Noise reduction is by resistive absorption, by whichthe amplitude of sound waves is reduced by converting most of theacoustic energy into heat. Other applications include abradable seals,using nickel alloy (Hastelloy X) fibers, and high-temperature thermalinsulation, using an iron, chromium, aluminum, and yttrium alloy.

SOUND AND VIBRATION INSULATORS 881




Vibration insulators, or isolators, to reduce vibrations that pro-duce noises, are usually felt or fiberboards placed between themachine base and the foundation, but for heavy pressures they maybe metal wire helically wound or specially woven, deriving their effec-tiveness from the form rather than the material. Keldur, of Quimby& Co., is a fibrous insulating material made up in sheets 0.75 in (1.91cm) thick, with a resilient binder. Korfund isolator, of KorfundDynamics Co., is a resilient mat of cork treated with oil and bound ina steel frame. It will take loadings up to 4,000 lb/ft2 (19,528 kg/m2).Vibro-Insulator, of Karman Rubber Co., is an isolator of Ameripolsynthetic rubber. Plastic foams in sheet or flexible tape form are alsoused as isolators for instruments. Isoloss, of E-A-R SpecialtyComposites, is a high-density urethane foam for shock absorption.Viscolas, of the same company, is sheet or molded viscoelastic poly-mers for shock absorption. Isodamp, also of E-A-R, is vinyl-basedsheet and foam for vibration and shock control.

SOYBEAN OIL. Also known as soya bean oil. A pale-yellow oilobtained by expression from the seeds of the plant Glycine soya, nativeto Manchuria but grown in the United States. Soybean oil is a linolenicacid oil; in contrast, the other three major oilseed oils—cottonseed,peanut, and sunflower—are oleic-linolenic acid oils, because they con-tain more than 50% of these fatty acids. It is primarily a food oil buthas an undesirable off-flavor unless highly purified. It is also used as adrying oil for linoleum, paints, and varnishes, or for mixing with lin-seed oil, although the untreated oil has only half the drying power oflinseed oil. It is also used in core oils and in soaps. The bean containsup to 20% oil. The average yield factor is 15%, but by trichlorethyleneextraction a bushel of beans will yield 11 lb (5 kg) of oil and 46 lb (21kg) of high-protein meal containing less than 1% oil. The oil contentdecreases in warm climates. Southern-grown soybeans contain 2 to 5%less oil than those grown in Illinois. The usual conversion factor is 8.5lb (4 kg) of oil and 48 lb (22 kg) of meal per bushel of beans. The oil iseasy to bleach, has good consistency as a food oil, and does not becomerancid easily, but has less flavor stability than many other oils. Thereare 280 varieties of the bean grown in the United States and 2,500varieties listed. The pods contain two or three beans which range incolor from light straw through gray and brown to nearly black. Mostvarieties are straw-colored or greenish yellow. The stalks and leavesof the plant contain much nitrogen, and about half of the crop is usu-ally plowed under for fertilizer.

The specific gravity of the oil is about 0.925, iodine value 134, andit should have a maximum of not more than 1.5% free fatty acids andnot more than 0.3 moisture and volatile matter. The fractionated oil

882 SOYBEAN OIL




yields 15% cut soybean oil of an iodine value of 70 to 90, used forsoaps, lubricants, and rubber compounding; 72% selected-acid oil ofan iodine value of 145 to 155, used for varnish and paint oils alone orin blends with other oils, or for glycerin making; 13% bottoms, usedfor soaps, lubricants, and giving a by-product pitch used in insulationand mastic flooring. Snowflake oil, of Archer-Daniels-Midland Co.,is a heavy-bodied, oxidized soybean oil for paints. It has a specificgravity of 0.986 to 0.989 and iodine number from 64 to 95. Specialkettle-bodied and blown grades for use in coatings, caulks, and put-ties are available from Werner G. Smith, Inc. Soyalene, of the samecompany, is an alkali-refined soybean oil for varnishes. The specificgravity is 0.924, and the iodine number is 130. Epoxidized soybeanoil is used in vinyl and alkyd resins as a plasticizer and to increaseheat resistance. A very large use of soybean oil is in the making ofmargarine.

Soybean meal is the product obtained by grinding the soybeanchips from the expeller process, or the soybean oil cake from thehydraulic process. The meal is marketed as stock feed or fertilizer. Itis chiefly used as a protein feed for dairy cattle, but it is inferior tofish meal for poultry, as it lacks the mineral salts and vitamins of fishmeal. Soybean meal hardened with formaldehyde is used as a fillerwith wood flour in plastics to give better flow in molding. Gelsoy is aprotein gel extracted from soybean meal. It is used in foodstuffs as athickening agent, and is also used as a strong adhesive. Genistein,found in soybean curd, called tofu, and in soy milk, soy protein iso-lates, and most soy flours, may be an anticarcinogen. Soy sauce doesnot contain the substance, but its principal flavor component containsa substance called HEMF, also a possible anticarcinogen.

Soybean flour for bakery food products for the U.S. market is madefrom meal that has been treated by acidulated washing to remove the sol-uble enzymes and sugars that carry the taste. Meal produced by heat pro-cessing averages 40% protein and 20 fats, while meal from solventextraction has 42 to 50 protein and a maximum of 2.5 fats. Further pro-cessing of the meal to remove sugars and other materials varies the finalprotein content of the flour, and meals from different types of beans varyin content. The protein content can be increased by removing the soy hullsbefore (front-end dehulling) or after (tail-end dehulling) solvent extraction.The Promax and Isopro soybean flours, of Griffith Laboratories, forhigh-protein additions to foodstuffs, contain 70% protein with all flavorremoved, and are high in lysine. They have a pH of 5.5 and 7.0, respec-tively. Soy protein, of General Mills, used in canned soups and meatproducts, is toasted to eliminate all enzyme activity. It contains 50% pro-tein with 2 lecithin and 3 lysine. Promine, of Central Soya Co., is a 93%concentrate of soybean proteins, used for thickening and enriching soup

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mixes. Supro 610, of Ralston Purina Co., is a spray-dried powder, 95%protein, with a light cream color and no bitter flavor.

SPECULUM METAL. An alloy formerly used for mirrors and in opticalinstruments. It contains 65 to 67% copper, the balance tin. It takes abeautiful polish and is hard and tough. An old Roman mirror con-tained about 64% copper, 19 tin, and 17 lead; and an Egyptian mirrorcontained 85% copper, 14 tin, and 1 iron. The old Greek mirrors werecarefully worked out with 32% tin and 68 copper. They had 70% of thereflecting power of silver, with a slight red excess of reflection thatgave a warm glow, without the blue of nickel or antimony. This alloyis now plated on metals for reflectors. A modern telescope mirror con-tains 70% copper and 30 tin. Chinese speculum contains about 8%antimony and 10 tin. Speculum plate, which has been advocated bythe Tin Research Institute for electroplating, to give a hard, white,corrosion-resistant surface for food processing equipment and opticalreflectors, has 55% copper and 45 tin. It is harder than nickel andretains its reflectivity better than silver.

SPERM OIL. The waxy oil extracted from the head cavity of thesperm whale, Physeter breviceps and P. catadon, and theBottlenose whale, P. macrocephalus. Sperm whales have teeth andfeed in deep water on squid and large animal life. The male spermwhale attains a length of 60 ft (18 m) and the female about 38 ft (12m). The spermaceti is first separated out, leaving a clear, yellow oil.It is purified by being pressed at a low temperature. It is gradedaccording to the temperature of pressing. A good grade of sperm oilhas a specific gravity of 0.875 to 0.885 and a flash point above 440°F(227°C). Oils from other whale species, such as the humpback, fin,and sulfurbottom, have a specific gravity of 0.91 to 0.93. Inferiorgrades of sperm oil may be from sperm whale blubber. Commercialsperm oil is likely to be one-third head oil and two-thirds body oil.Sperm oil differs from fish oil and whale oil in consisting chiefly ofliquid waxes of the higher fatty alcohol esters and not fats. Spermoil absorbs very little oxygen from the atmosphere and resistsdecomposition even at temperatures above 400°F (204°C), and it willpour below its cloud point of 38 to 45°F (3 to 7°C). It wets metal sur-faces easily. It is thus a valuable lubricating oil. It was formerlyused as a lamp oil, burning with a white shining flame. It is also anexcellent soap oil. Sperm 42, of Werner G. Smith, Inc., is a spermoil with carbon chains of C10 to C22, and it is emulsifiable in cold orwarm water. Sulfonated sperm oil is used as a wetting agent fortextiles, and it is also valued for cutting oils, crankcase oil, andhigh-pressure lubricants. Smithol 25, of the same company, is a

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synthetic fatty-acid oil resembling sperm oil and having the sameuses. It is a light-colored, odorless oil with high viscosity, a low pourpoint of 16°F (27°C), and an iodine value of 105. Maysperm is asulfurized sperm-oil replacement from Mayco Oil & Chemical Co. Itis used as a lubricant additive.

Spermaceti is the white, crystalline flakes of fatty substance, orwax, that separate out from sperm oil on cooling after boiling. It iscetyl palmitate, a true wax, and does not yield glycerin whensaponified. It is purified by pressing, and the triple-refined is snowwhite. It is also separated out from dolphin-head oil. Spermaceti isodorless and tasteless, has a melting point of 43°C, and is insoluble inwater, but soluble in hot alcohol. It burns with a bright flame. It wasformerly used for candles but now is employed chiefly as a fine waxfor ointments and compounds. Sperm oil and spermaceti are inedibleand indigestible. Cetyl alcohol, C16H33OH, originally obtained fromspermaceti, is now made synthetically from ethyl palmitate.

A synthetic spermaceti wax from Sherex Chemical Co., calledStarfol Wax GG, is used in cosmetic emollients, drawing compounds,finishing aids, lubricants, and leather treatment. Synaceti 116 is afine-chemical and pharmaceutical grade from Werner G. Smith, Inc.White flakes of a 90% cetyl palmitate grade, Kessco 653, fromStepan Chemical Co., are employed as a viscosity modifier. Straplitzis a similar material from Strahl & Pitsch, Inc. A substitute wax thatis compositionally different from spermaceti is extracted from thejojoba plant. Hydroba-70 is such a material, produced by JojobaGrowers & Processors, Inc.

SPICE. An aromatic vegetable substance, generally a solid used inpowdered form, employed for flavoring foods. There is no sharp divid-ing line between flavors and spices, but in general a spice is a materialthat is used to stimulate the appetite and increase the flow of gastricjuices. Spices are not classified as foods in themselves, having littlefood value, but as food accessories. Pepper is distinctly a spice, thoughnot grouped with the spices. Some spices are also used widely as fla-vors and in perfumes, and in medicine either for antiseptic or other val-ues or to disguise the unpleasant taste of drugs. A condiment is astrong spice, or a spice of sharp taste, although the word is often erro-neously applied to any spice. A savory is a fragrant herb or seed usedfor flavor in cooking. Spices are obtained from the stalks, bark, fruits,flowers, seeds, or roots of plants. Microground spices, used to giveuniform distribution in the quantity manufacture of foodstuffs, arespices ground to microscopic fineness in a roller mill. The most popularspices in the United States, in the order of quantity used, are: cinna-mon, nutmeg, ginger, cloves, allspice, poppy seed, and caraway seed.

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Since ground spices lose flavor rapidly by the loss of volatile oils, theparticles are sometimes coated with dextrose or a water-soluble gum.Spisoseals are ground spices with coated particles.

Allspice, also known as pimento and Jamaica pepper, is thedried, unripe fruit of the small evergreen tree Pimenta officinalis ofthe myrtle family growing in the West Indies and tropical America.The fruit is a small berry which when dried is wrinkled and reddishbrown. It has a flavor much like a combination of clove, nutmeg, andcinnamon. Pimento oil is a fragrant essential oil distilled from theberries, which contain 4%. It contains eugenol and cineol and is usedin flavors, in bay rum, and in carnation perfumes. Coriander is thedried fruit of the perennial plant Coriandrum sativum grown in theMediterranean countries and India. It is one of the oldest spices andhas a pleasant, aromatic taste. Oil of coriander, extracted from thedried seed, is used in medicine, beverages, and flavoring extracts. Ithas a higher aromatic flavor than the fruit. Savory is a fragrant herbof the mint family, Satureia hortensis, used in cooking, and in medi-cine as a carminative. It contains carvacrol, a complex phenol alsooccurring in caraway and camphor. The word savory also designatesother herbs used directly in foods as flavors.

Celery seed, used as a savory, is from the plant Apium graveolens.The best-quality leafstalks, known as celery, are bleached white andeaten raw or cooked. The plant is widely grown for seed in France andSpain. Celery-seed oil is a pale-yellow oil extracted from the seedsand used as a flavor and in perfumery. Fennel is the dried, oval seedof the perennial plants Foeniculum vulgare and F. dulce. The stalks ofthe latter are blanched and eaten as a vegetable in Europe. Fennel isused as a flavoring in confectionery and liqueurs, and as a carminativein medicine. Fennel oil is a pale yellowish essential oil with specificgravity of 0.975, distilled from the seed. It has an aromatic odor and acamphorlike taste with a secondary sweetish, spicy taste. It containsfenchone, C10H16O, an isomer of camphor, with also pinene, cam-phene, and anethole, or anise camphor, C3H5C6H4OCH3. The latteris used in dentifrices and pharmaceuticals. Fenugreek is the seedfrom the long pods of the annual legume Trigonella foenum-graecum,native to southern Europe. It is used in curries, in medicine, and formaking artificial maple flavor. Oregano, used as an ingredient inchili powder and as a spice in a variety of dishes, is the pungent herbColeus amboinica.

Dill seed, from the herb Anethum graveolens, of the parsley family,is used as a condiment for pickles. Dill leaves are used as seasoningfor soups, sauces, and pickles. Dill oil, extracted from the whole herb,is used as a flavor in the food industry. It resembles caraway oil andhas a finer flavor than dill-seed oil, which is more plentiful, but dillflavor prepared from the whole seed is stronger. Dill is grown in the

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central United States and in central Europe. Cardamon is the highlyaromatic and delicately flavored seeds of the large perennial herbElettaria cardamomum, of India, Ceylon, and Central America. Theseeds are used in pickles, curries, and cakes, and the oil is employedas a flavor. Garlic is the root bulb of the lily Allium sativum, used asa condiment, and also used in medicine as an expectorant under thename of allium. It contains allyl sulfide, a liquid of composition(CH2:CHCH2)2S, which gives it a pungent odor and taste. Allicine,extracted from garlic, is used in medicine as an antibacterial. It is anoily liquid with a sharp garlic odor.

Cumin is the seed of Cuminum cyminum, the true cumin, andNigella sativa, the black cumin, both of India. The seed is used inconfectionery and in curries. A kind of black cumin known as shiahzira, from the plant Carum indicum of India, is superior in taste andfragrance to ordinary cumin. Caraway is the spicy seed of the bien-nial herb C. carvi of Europe and north Africa. The seeds are used oncookies. Caraway oil, distilled from the seeds, contains carvone andlimonene, and in combination with cassia gives a pleasant odor. It isused in soap, perfumes, and mouthwashes. Sage is the grayish-green,hairy leaves of the shrublike plant Salvia officinalis used as a spice.It is cultivated extensively in the Mediterranean region. Oil of sageis used in perfumery. Clary sage oil is distilled from the flowers of S.sclarea of France, Italy, and north Africa. It has the odor of a mixtureof ambergris, neroli, and lavender, and is used in flavoring vermouthliquor and muscatel wines, and in eau de cologne. Sassafras is some-times classified as a spice but is a flavor. It is the aromatic spicy barkof the root of the tree Sassafras albidum which grows wild in theeastern United States. It is used mostly for making root beer, but alsofor flavoring tobacco, and in patent medicines. Sassafras oil is an oilextracted from the whole roots, which contain 2% of the yellow oil,and is used in medicine, perfumery, and soaps. It produces artificialheliotrope. The oil contains safrol, C10H10O2, also produced frombrown camphor oil. Brazilian sassafras oil, or ocotea oil, is dis-tilled from the root of the tree Ocotea cymbarum, also of the laurelfamily. The root yields about 1% of an oil which contains 90% safrol,and has the odor and flavor of American sassafras oil. Sarsaparillais an oil obtained from the long brown roots of the climbing vineSmilax regellii of Honduras, S. aristolochiaefolia of Mexico, and otherspecies, all growing in tropical jungles. The roots are used in medi-cine. The oil is used as a flavor. It is odorless, but has an acrid sweettaste. It contains saponins.

Wintergreen oil is from the leaves of the small evergreen plantGaultheria procumbens of the middle Atlantic states. The oil does notexist in the plant but is formed by the reaction between a glucosideand an enzyme when the chopped leaves are steeped in water. It is

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largely methyl salicylate, C8H8O3. It is used in flavoring candiesand soft drinks and in medicine. Hop oil, used to give hop flavor tocereal beverages, and also in perfumes, is obtained from lupulin,a glandular powder found in the female inflorescence of the hop plant,Humulus lupulus. Hops are used directly in making beer, and the oilis produced from the discard hops which contain 0.75% oil. Aniseseed is from the annual plant Pimpinella anisum grown in theMediterranean countries and in India. The best grades come fromSpain. The seed is used in flavoring in the baking industry. The dis-tilled oil, anise oil, is used in perfumes and in soaps, and in theliqueur known as anisette. The oil contains choline and is used inmedicine as a carminative and expectorant.

SPINEL. A magnesium aluminate, MgO Al2O3, occurring as octa-hedral crystals of varying colors due to impurities of iron, manganese,or chromium. The best transparent stones are used as gems. Spinel isfound as crystals or rolled pebbles in gem gravels with corundumstones; the ruby spinel often occurs with the true ruby. It has adeep-red color, but the variety almandine is violet.

Synthetic spinel was originally made in Germany to replace rubyand sapphire for instrument bearings because it is easier to cut andthus conserves diamond abrasive. Spinel is produced by Linde inthe forms of drawing dies, gages, wearing parts, orifices, and balls.The composition is MgO 3.5Al2O3, and the crystal structure iscubic. The specific gravity is 3.61, the melting point is about 3704°F(2040°C), and the Mohs hardness is 8. Like corundum, it is notattacked by common acids or by sodium hydroxide. The spinel pow-der from which the crystals are flame-grown is made by calcining amixture of pure ammonium sulfate and ammonium magnesium sul-fate. Much synthetic spinel is used for synthetic gems, the colorsbeing obtained with metal oxides. Small amounts of chromic oxidegive the tinted crystals of sapphire, while up to 6% is used for thedark ruby colors. Blue is obtained with oxides of iron and titania,and green is from cobalt oxide. Golden topaz is colored with nickeland magnesium oxides. The aquamarine spinel is tinted with acomplex mixture of nickel, cobalt, vanadium, and titanium oxides.

SPODUMENE. A mineral of composition Li2O Al2O3 4SiO2, withsome potassium and sodium oxides. It is the chief ore of the metallithium, but it requires a higher temperature for sintering than lepi-dolite, and the sinter is more difficult to leach. It is found in SouthDakota and the Carolinas, and has an average content of 4% Li2O,ranging from 2.9 to 7.6%. Crystals of spodumene in South Dakota are8 to 10 ft (2 to 3 m) long and 1 ft (0.3 m) in thickness, appearing like

888 SPINEL




logs of wood, with as high as 6.5% lithium. The specific gravity is 3.13to 3.20, and the melting point is 2543 to 2597°F (1395 to 1425°C).Spodumene is three times more active than feldspar as a flux inceramics, giving fluidity, increasing surface tension, and eliminatingpinholes. A mixture of 25% spodumene with 75 feldspar is an activevitrifying agent in ceramics. The melting point of the mixture is2030°F (1110°C), which is below the usual minimum temperatureused for chinaware; it thus forms a glaze. Lithospar is a name forfeldspar and spodumene from the pegmatites of King’s Mountain,North Carolina. In Germany lithium is obtained from the lithiummica zinnwaldite, which is a mixture of potassium-aluminumorthosilicate and lithium orthosilicate with some iron, and containsless than 3% Li2O. Kryolithionite, a mineral found in Greenland,has composition Na3Li3(AlF6)2 and contains up to 11.5% Li2O. It has acrystal structure resembling garnet. A transparent, emerald-greenspodumene in small crystals, known as hiddenite, is found in NorthCarolina and is cut into gemstones.

SPONGE. The cellular skeleton of a marine animal of the genusSpongia, of which there are about 3,000 known species, only 13 ofwhich are of commercial importance. It is employed chiefly for wipingand cleaning, as it will hold a great quantity of water in proportion toits weight, but it also has many industrial uses such as applyingglaze to pottery. Sponges grow like plants, attached to rocks on thesea bottom. They are prepared for use by crushing to kill them, scrap-ing off the rubbery skin, macerating in water to remove the gelati-nous matter, and bleaching in the sun. Tarpon Springs, Florida, is thecenter of U.S. sponge fishing, but most of the best sponges have comefrom the Mediterranean and Red Seas.

The prepared sponge is an elastic, fibrous structure chemicallyallied to silk. It has sievelike membranes with small pores leading intopear-shaped chambers. The best sponges are spheroidal, regular,and soft. Commercial sponges for the U.S. market must have a diameterof 4.5 in (11.4 cm) or more. Most of the Florida sponges are thesheepswool sponge, Euspongia lachne, used for cleaning andindustrial sponging. The Rock Island sponge, from Florida, andthe Key wool sponge are superior in texture and durability to theBahama wool sponge, which is coarser, more open, and lessabsorbent. The Key yellow sponge is the finest grade. The grasssponge, E. graminea, of the Caribbean, is inferior in shape and texture.The fine honeycomb sponge, Hippiospongia equina, of theMediterranean Sea, is of superior grade and has been preferred as abath sponge. About 80% of the north African catch consists of honey-comb sponges, with the remainder Turkey cup sponge, E. officinalis,

SPONGE 889




and zimocca sponge, E. zimocca. The Turkey cup is rated as thefinest, softest, and most elastic of the sponges, but the larger of thezimocca sponges are too hard for surgical use and are employed forindustrial cleaning. Sponges for industrial and household uses havenow been largely replaced by foamed rubbers and plastics.

SPONGE IRON. Iron made from ferrous sand and pressed into bri-quettes, which can be charged directly into steel furnaces instead of pigiron. It was originally made on a large scale in Japan where only low-grade sandy ores were available. Sponge iron is made by charging thesand continuously into a rotary furnace to drive off the light volatileproducts and reduce the iron oxide to metallic iron, which is passedthrough magnetic separators, and the finely divided iron briquetted.Unbriquetted sponge iron, with a specific gravity of 2, is difficult to meltbecause of the oxidation, but briquetted material, with a specific gravityof 6, can be melted in electric furnaces. Sponge iron, to replace scrap insteelmaking, is also made from low-grade ores by reducing the ore withcoke-oven gas or natural gas. It is not melted, but the oxygen is drivenoff, leaving a spongy, granular product. As it is very low in carbon, it isalso valuable for making high-grade alloy steels.

A form of sponge iron employed as a substitute for lead for couplingpackings was made in Germany under the name of sinterit. Thereduction is carried out in a reducing atmosphere at a temperature of2192 to 2462°F (1200 to 1350°C), instead of heating the iron oxidewith carbon. Since the porous iron corrodes easily, it is coated withasphalt for packing use. Iron sponge, employed as a purifier forremoving sulfur and carbonic acid from illuminating gas, is asesquioxide of iron obtained by heating together iron ore and carbon.It has a spongy texture and is filled with small cells.

SPRENGLE EXPLOSIVES. Chlorate compounds that have been ren-dered reasonably safe from violent explosion by separating the chloratefrom the combustible matter. The potassium chlorate, made into porouscartridges and dipped, just before use, in a liquid combustible such asnitrobenzene or dead oil, was called rack-a-rock. It is a mixture of79% chlorate and 21 nitrobenzene. Rack-a-rock special contains, inaddition, 12 to 16% picric acid. Sprengle explosives were formerly usedas military explosives, are very sensitive to friction and heat, and arenow valued only for mining or when it is desired to economize onnitrates. Cheddite is a French explosive consisting of a chlorate withan oily material, such as castor oil, thickened by a nitrated hydro-carbon dissolved in it. A typical cheddite has 80% potassium chlorate, 8castor oil, and 12 mononitronaphthalene. With sodium chlorate it isless sensitive to detonation and more powerful but is hygroscopic.

890 SPONGE IRON




Potassium chlorate cheddite is a soft, yellowish, fine-grained material,and is a slow, mild explosive which will split rocks rather than shatterthem. Minelite is a chlorate with paraffin wax. Steelite is a chlorateexplosive with rosin. Prométhée, or Explosive O3, is another Frenchchlorate explosive. In this explosive the oxygen carrier consists of 95%potassium chlorate and 5 manganese dioxide, and the combustible con-tains 50% nitrobenzene, with turpentine and naphtha. It is extremelysensitive and will explode by friction. Silesia is a German high explosiveused for blasting. It is potassium chlorate with rosin, with some sodiumchlorate to make it less sensitive. Hellhoffite is a mixture of nitric acidand dinitrobenzene, which are combined in a shell on impact.Panclasites are a class similar to the Sprengle type, in which carbondisulfide, nitrobenzene, and petroleum oil are combined with liquidnitrogen peroxide.

SPRING STEEL. A term applied to any steel used for springs. Themajority of springs are made of steel, but brass, bronze, nickel silver,and phosphor bronze are used where their corrosion resistance or elec-trical conductivity is desired. Carbon steels, with from 0.50 to 1.0%carbon, are much used, but vanadium and chromium-vanadium steelsare also employed, especially for heavy car and locomotive springs.Special requirements for springs are that the steel be low in sulfur andphosphorus, and that the analysis be kept uniform. For flat or spiralsprings that are not heat-treated after manufacture, hard-drawn orrolled steels are used. These may be tempered in the mill shape. Musicwire is widely employed for making small spiral springs. A much-usedstraight-carbon spring steel has 1% carbon and 0.30 to 0.40 man-ganese, but becomes brittle when overstressed. ASTM carbon steelfor flat springs has 0.70 to 0.80% carbon and 0.50 to 0.8 manganese,with 0.04 maximum each of sulfur and phosphorus. Motor springs aremade of this steel rolled hard to a tensile strength of 250,000 lb/in2

(1,724 MPa). Watch spring steel, for mainsprings, has 1.15% carbon,0.15 to 0.25 manganese, and in the hard-rolled condition, has an elasticlimit above 300,000 lb/in2 (2,069 MPa).

Silicon steels used for springs have high strength. These steelsaverage about 0.40% carbon, 0.75 silicon, and 0.95 manganese, withor without copper, but the silicon may be as high as 2%. Flexo steel,used for automobile leaf springs and recoil springs, contains 2% sili-con, 0.75 manganese, and 0.60 carbon. The elastic limit is 100,000 to300,000 lb/in2 (690 to 2,069 MPa), depending on drawing tempera-ture, with Brinell hardness 250 to 600.

Manganese steels for automotive springs contain about 1.25% man-ganese and 0.40 carbon, or about 2 manganese and 0.45 carbon.

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When heat-treated, the latter has a tensile strength of 200,000 lb/in2

(1,379 MPa) and 10% elongation. Part of the manganese may bereplaced by silicon, and the silicon-manganese steels have tensilestrengths as high as 270,000 lb/in2 (1,862 MPa). The addition ofchromium or other elements increases ductility and improves physi-cal properties. Uma spring steel is a chromium-manganese steelwith 1 to 1.2% chromium, 0.80 to 1 manganese, and about 0.50 car-bon. In the rolled condition it has an ultimate strength of 135,000lb/in2 (931 MPa) and Brinell hardness up to 332. Manganese steelsare deep-hardening but are sensitive to overheating. The addition ofchromium, vanadium, or molybdenum widens the hardening range.

Wire for coil springs ranges in carbon from 0.50 to 1.20%, and in sul-fur from 0.028 to 0.029. Bessemer wire contains too much sulfur forspring use. Cold working is the method for hardening the wire and forraising the tensile strength. A 0.85% carbon rod, with an ultimatestrength of 140,000 lb/in2 (965 MPa), when drawn with four or fivepasses through dies, will have a strength of 235,000 lb/in2 (1,620MPa). Wire drawn down to a diameter of 0.015 in (0.038 cm) may havean ultimate strength of 400,000 lb/in2 (2,758 MPa). The highest gradesof wire are referred to as music wire. The second grade is called hard-drawn spring wire. The latter is a less expensive, basic open-hearthsteel with manganese content of 0.80 to 1.10%, and an ultimatestrength up to 300,000 lb/in2 (2,069 MPa). Specially treated carbonsteels for springs are sold under trade names such as Enduria andResilla, the latter being a silicon-manganese spring steel.

For jet-engine springs and other applications where resistance tohigh temperatures is required, stainless steel and high-alloy steelsare used. But while these may have the names and approximate com-positions of standard stainless steels, for spring-wire use their manu-facture is usually closely controlled. For example, when the carboncontent is raised in high-chromium steels to obtain the needed springqualities, the carbide tends to collect in the grain boundaries andcause intergranular corrosion unless small quantities of titanium,columbium, or other elements are added to immobilize the carbon.Blue Label stainless is Type 302 stainless steel of highly controlledanalysis for coil springs. Alloy NS-355 is a stainless steel having atypical analysis of 15.64% chromium, 4.38 nickel, 2.68 molybdenum, 1manganese, 0.32 silicon, 0.12 copper, with the carbon at 0.14. Themodulus of elasticity is 29.3 106 lb/in2 (202,000 MPa) at 80°F (27°C)and 24 106 lb/in2 (165,000 MPa) at 800°F (427°C). 17-7 PH stain-less steel has 17% chromium, 7 nickel, 1 aluminum, and 0.07 carbon.Wire has a tensile strength up to 345,000 lb/in2 (2,379 MPa). Springwire for high-temperature coil springs may contain little or no iron.Alloy NS-25, for springs operating at 1400°F (760°C), contains about

892 SPRING STEEL




50% cobalt, 20 chromium, 15 tungsten, and 10 nickel, with not morethan 0.15 carbon. Annealed wire, drawn to a 30% reduction, has atensile strength of 240,000 lb/in2 (1,655 MPa) with 8% elongation.Matreloy, for high-temperature springs, contains 39% chromium, 4molybdenum, 2 titanium, 1 aluminum, and the balance nickel. Therolled metal has a yield strength of 275,000 lb/in2 (1,896 MPa) and, at1400°F (760°C), retains a strength of 120,000 lb/in2 (827 MPa).

SPRUCE. The wood of various coniferous trees of northern Europeand North America. Spruce is a leading commercial wood of north-ern Europe and is exported from the Baltic region as white fir andwhite deal. It is also called Norway spruce and spruce fir. Thewood is white and has a straight, even grain. It is tough and elasticand is more difficult to work than pine. The density is 36 lb/ft3 (577kg/m3). Norway spruce is Picea abies, and this tree yields the Juraturpentine of Europe. Spruce is used for making paper pulp, forpacking boxes, and as a general-utility lumber. White spruce is fromthe tree P. canadensis, of the United States and Canada. It has quitesimilar characteristics. Red spruce, P. rubra, is the chief lumberspruce in the eastern United States. It is also called yellow spruce,West Virginia spruce, and Canadian spruce. Black spruce,P. mariana, of New England, eastern Canada, and Newfoundland, isused for making paper pulp. It is also called blue spruce, bogspruce, and spruce pine. White spruce, or shingle spruce, isfrom P. glauca. It is also called skunk spruce because of the pecu-liar odor of the foliage. All of these three species are called easternspruce, and they grow from Nova Scotia to Tennessee and west-ward to Wisconsin except that red spruce does not grow in the lakestates. All are mountain trees and are slow-growing. Silver spruce,yellow spruce, Sitka spruce, or western spruce is from theenormous tree P. sitchensis, of the west coast of the United Statesand Canada. It is soft and lightweight, but strong, close-grained,and very free from knots. The wide sapwood is creamy white, andthe heartwood pinkish to brownish. The weight is less than that ofeastern spruce, but it has high strength in proportion to weight. Thetrees reach a height of 280 ft (85 m) and a diameter of 10 ft (3 m) in600 years, but growth is rapid in early life. The wood is used forboxes, crates, millwork, and paper pulp. It is particularly adapted forgroundwood pulp, giving higher strength in paper than most ground-wood. The various species of commercial spruce have an average spe-cific gravity, when kiln-dried, of 0.40, a compressive strength of 840lb/in2 (6 MPa) perpendicular to the grain, and a shearing strength of750 lb/in2 (5 MPa) parallel to the grain. It combines stiffness andstrength per unit weight and has a uniform texture free from pitch.

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Japanese spruce is from Abies mariesii, and Himalayan spruceis from P. morinda. The latter resembles Norway spruce.

Spruce gum is the gum exudation of P. rubra, P. mariana, and P.canadensis of the northeastern United States and Canada. It exudesfrom cuts in the trees as a transparent, viscous liquid which hardenswhen it loses the volatile oil. It occurs on all parts of the tree, and thenodules of gum are sometimes as large as an egg. Spruce oil isextracted from the needles. In colonial days the young twigs wereboiled, and the liquid, mixed with molasses, was used as a beverage.The gum is brown or reddish black and has a turpentinelike odor anda bitter, pungent taste. It is used in cough medicines and chewinggum.

SQUILL. Also known as red squill and sea onion. A reddish powderused chiefly for the control of rats in warehouses and docks. It is classi-fied as a cardiac glycoside, a category that includes digitalis. It isobtained from the onionlike bulb of the perennial plant Urginea mar-itima, which grows on the beaches of Italy and other Mediterraneancountries. The bulb is pear-shaped, from 1 to 6 lb (0.5 to 15 kg) inweight and 6 to 12 in (15 to 30 cm) in diameter. The outer scales are dry,brittle, and reddish brown, and the inner scales are cream color to deeppurple. Red squill powder is a powerful emetic to humans or animalsother than rats or mice. As rats and mice do not vomit, they are poi-soned by it, while it is harmless to poultry and domestic animals. It isalso used in medicine. It contains calcium oxalate, and in contact withskin it gives a sensation like nettle poisoning. White squill is anothervariety used in medicine as an emetic, heart tonic, and expectorant. Thesubstitute for red squill known as Antu, of Du Pont, is naphthylthiourea, a gray powder of little odor or taste about 100 times morepoisonous to rats than squill and not normally injurious to domestic ani-mals. Another poison more toxic to rats than squill is Ratbane 1080,which is sodium fluoracetic acid made synthetically. The poisonoccurs as natural fluoracetic acid in the gifblaar plant, Dichapetalumcymosum, of South Africa, which has been used locally for killingrodents. The poison, however, also kills domestic animals and can thusbe employed only in restricted places. The rodent poison known asWarfarin is a complex dicoumarol made under license of the WisconsinAlumni Research Foundation. Pival, of Atlantic Research Corp., is 2-pivalyl-1,3-indandione. It kills rats but is not toxic to other animals.Pivalyn is the same material in a water-soluble sodium salt form.

STAINLESS STEEL. A large and widely used family of iron-chromium alloys known for their corrosion resistance—notablytheir “nonrusting” quality. This ability to resist corrosion is attribut-

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able to a chromium-oxide surface film that forms in the presence ofoxygen. The film is essentially insoluble, self-healing, and nonporous.A minimum chromium content of 12% is required for the film’s forma-tion, and 18 is sufficient to resist even severe atmospheric corrosion.Chromium content, however, may range to about 30% and severalother alloying elements, such as manganese, silicon, nickel, or molyb-denum, are usually present. Most stainless steels are also resistant tomarine atmospheres, freshwater, oxidation at elevated temperatures,and mild and oxidizing chemicals. Some are also resistant to saltwa-ter and reducing media. They are also quite heat-resistant, someretaining useful strength to 1800°F (981°C). And some retain suffi-cient toughness at cryogenic temperatures. Thus, stainless steels areused in a wide range of applications requiring some degree of corro-sion and/or heat resistance, including auto and truck trim, chemicaland food processing equipment, petroleum-refining equipment, fur-nace parts and heat-treating hardware, marine components, architec-tural applications, cookware and housewares, pumps and valves,aircraft and aircraft-engine components, springs, instruments, andfasteners.

Stainless steels were first made in the United States in 1914 underEnglish and German patents. The original composition had 13.5%chromium and 0.35 carbon. The original Krupp austenitic, or KA steel,or simply austenitic steel, had 20% chromium and 7 nickel, which waslater balanced at 18–8. The eighteen-eight chromium-nickel steelswere called super stainless steels in England to distinguish them fromthe plain chromium steels. Today, wrought stainless steels alone includesome 70 standard compositions and many special compositions. They arecategorized as austenitic, ferritic, martensitic, or precipitation-hardening(PH) stainless steels, depending on their microstructure or, in the case ofthe PH, their hardening and strengthening mechanism. There are alsomany cast stainless steels having these metallurgical structures. Theyare known as cast corrosion-resistant steels, cast heat-resistant steels,and cast corrosion- and heat-resistant steels. Several compositions areavailable in powder form for the manufacture of stainless-steel powder-metal parts.

Except for the PH stainless steels, wrought stainless steels arecommonly designated by a three-digit numbering system of theAmerican Iron and Steel Institute. Wrought austenitic stainlesssteels constitute the 2XX and 3XX series, and the wrought ferriticstainless steels are part of the 4XX series. Wrought martensiticstainless steels belong to either the 4XX or 5XX series. Suffix let-ters, such as L for low carbon content or Se for selenium, are used todenote special compositional modifications. Cast stainless steels arecommonly known by the designations of the Alloy Casting Institute of

STAINLESS STEEL 895




the Steel Founders Society of America, which began with letters CAthrough CN and are followed by numbers or numbers and letters.Powder compositions are usually identified by the designations of theMetal Powder Industries Federation.

Of the austenitic, ferritic, and martensitic families of wroughtstainless steels, each has a general-purpose alloy. All of the others inthe family are derivatives of the basic alloy, with compositions tai-lored for special properties. The stainless steel 3XX series has thelargest number of alloys, and stainless steel 302, a stainless “18–8”alloy, is the general-purpose one. Besides its 17 to 19% chromiumand 8 to 10 nickel, it contains a maximum of 0.15 carbon, 2 man-ganese, 1 silicon, 0.4 phosphorus, and 0.03 sulfur. 302B is similarexcept for greater silicon (2 to 3%) to increase resistance to scaling.Stainless steels 303 and 303Se are also similar except for greatersulfur (0.15% minimum) and, optionally, 0.6% molybdenum in 303,and 0.06 maximum sulfur and 0.15 minimum selenium in 303Se.Both are more readily machinable than 302. Stainless steels 304and 304L are low-carbon (0.08 and 0.03% maximum, respectively)alternatives, intended to restrict carbide precipitation during weldingand, thus, are preferred to 302 for applications requiring welding.They may also contain slightly more chromium and nickel. Stainlesssteel 304N is similar to 304 except for 0.10 to 0.16% nitrogen. Thenitrogen provides greater strength than 302 at just a small sacrificein ductility and a minimal effect on corrosion resistance. Stainlesssteel 304 SCQ, of Carpenter Technology, is electroslag remelted andhas the same mechanical properties as conventional air-melted 304but greater cleanliness, that is, greater freedom from nonmetallicinclusions. It provides better resistance to fluid leakage under vac-uum or high-pressure conditions in thin-wall vessels. Stainless steelNAS86D, from Japan’s Nippon Yakin Kogyo, contains 16 chromium, 8nickel, 3 copper, 0.6 aluminum, and 0.2 molybdenum. Because of itscopper and aluminum contents, it has better drawability than 304and, having a tensile yield strength of 33,000 lb/in2 (228 MPa), it isabout 10% stronger. Stainless steel 305 has 0.12% maximum carbonbut greater nickel (10.5 to 13) to reduce the rate of work hardeningfor applications requiring severe forming operations.

Stainless steel 308 contains more chromium (19 to 21%) and nickel(10 to 12) and, thus, is somewhat more corrosion- and heat-resistant.Though it is used for furnace parts and oil refinery equipment, itsprincipal use is for welding rods because its higher alloy content com-pensates for alloy content that may be reduced during welding.

Stainless steels 309, 309S, 310, 310S, and 314 have still greaterchromium and nickel contents. 309S and 310S are low-carbon (0.08%maximum) versions of 309 and 310 for applications requiring welding.

896 STAINLESS STEEL




They are also noted for high creep strength. 314, which like 309 and310 contains 0.25% maximum carbon, also has greater silicon (1.5 to3), thus providing greater oxidation resistance. Because of the highsilicon content, however, it is prone to embrittlement during pro-longed exposure at temperatures of 1200 to 1500°F (649 to 816°C).This embrittlement, however, is only evident at room temperatureand is not considered harmful unless the alloy is subject to shockloads. These alloys are widely used for heaters and heat exchangers,radiant tubes, and chemical and oil refinery equipment.

Stainless steels 316, 316L, 316F, 316N, 317, 317L, 321, and 329are characterized by the addition of molybdenum, molybdenum andnitrogen (316N), or titanium (321). 316, with 16 to 18% chromium, 10to 14 nickel, and 2 to 3 molybdenum, is more corrosion- and creep-resistant than 302- or 304-type alloys. 316L is the low-carbonversion for welding applications; 316F, because of its greater phospho-rus and sulfur, is the “free-machining” version; and 316N contains asmall amount of nitrogen for greater strength. 317 and 317L areslightly richer in chromium, nickel, and molybdenum and, thus,somewhat more corrosion- and heat-resistant. Like 316, they are usedfor processing equipment in the oil, chemical, food, paper, and phar-maceutical industries. 321 is titanium-stabilized to inhibit carbideprecipitation and provide greater resistance to intergranular corro-sion in welds. 329, a high-chromium (25 to 30%), low-nickel (3 to 6)alloy with 1 to 2 molybdenum, is similar to 316 in general corrosionresistance but more resistant to stress corrosion. Stainless steel330, a high-nickel (34 to 37%), normal-chromium (17 to 20), 0.75 to1.5 silicon, molybdenum-free alloy, combines good resistance to car-burization, heat, and thermal shock.

Stainless steels 347 and 348 are similar to 321 except for the useof columbium and tantalum instead of titanium for stabilization. Also,348 contains a small amount (0.2%) of copper. Both have greatercreep strength than 321, and they are used for welded components,radiant tubes, aircraft-engine exhaust manifolds, pressure vessels,and oil refinery equipment. 384, with nominally 16% chromium and18 nickel, is another low-work-hardening alloy used for severe cold-heading applications.

The stainless steel 2XX series of austenitics comprises 201, 202,and 205. They are normal in chromium content (16 to 19%), but lowin nickel (1 to 6), high in manganese (5.5 to 15.5), and with 0.12 to0.25 carbon and some nitrogen. 201 and 202 have been called the low-nickel equivalents of 301 and 302, respectively. 202, having 17 to 19%chromium, 7.5 to 10 manganese, 4 to 6 nickel, and a maximum of 1silicon, 0.25 nitrogen, 0.15 carbon, 0.06 phosphorus, and 0.03 sulfur,is the general-purpose alloy. 201, which contains less nickel (3.5 to

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5.5%) and manganese (5.5 to 7.5), was prominent during the Koreanwar due to a nickel shortage. 205 has the least nickel (1 to 1.75%) andthe most manganese (14 to 15.5), carbon (0.12 to 0.25), and nitrogen(0.32 to 0.40) contents. It is said to be the low-nickel equivalent of 305and has a low rate of work hardening that is useful for parts requir-ing severe forming operations.

Like stainless steels in general, austenitic stainless steels have adensity of 0.28 to 0.29 lb/in3 (7,750 to 8,027 kg/m3). Unlike some otherstainless steels, they are essentially nonmagnetic, although mostalloys will become slightly magnetic with cold work. Their meltingpoint range is 2500 to 2650°F (1371 to 1454°C), specific heat at 32 to212°F (0 to 100°C) is about 0.12 Btu/(lb °F) [502 J/(kg K)], and elec-trical resistivity at room temperature ranges from 27 to 31 in (69to 78 cm). Types 309 and 310 have the highest resistivity, and201 and 202 the lowest.

Most are available in many mill forms and are quite ductile in theannealed condition, tensile elongations ranging from 35 to 70%,depending on the alloy. Although most cannot be strengthened byheat treatment, they can be strengthened appreciably by cold work.In the annealed condition, the tensile yield strength of all theaustenitics falls in the range of 30,000 to 80,000 lb/in2 (207 to 552MPa), with ultimate strengths in the range of 75,000 to 120,000 lb/in2

(517 to 827 MPa). But cold-working 201 or 301 sheet just to the half-hard temper increases yield strength to 110,000 lb/in2 (758 MPa) andultimate strength to at least 150,000 lb/in2 (1,034 MPa). Tensile mod-ulus is typically 28 106 to 29 106 (193 103 to 199 103 MPa)and decreases slightly with severe cold work. As to high-temperaturestrength, even in the annealed condition most alloys have tensileyield strengths of at least 12,000 lb/in2 (83 MPa) at 1500°F (815°C),and some (308, 310) about 20,000 lb/in2 (138 MPa). Types 310 and 347have the highest creep strength, or stress-rupture strength, at 1000to 1200°F (538 to 649°C). Annealing temperatures range from 1750 to2100°F (954 to 1149°C), initial forging temperatures range from 2000to 2300°F (1093 to 1260°C), and their machinability index is typically50 to 55, 65 for 303, and 303Se, relative to 100 for 1112 steel.

Among the many specialty wrought austenitic stainless steelsare a number of nitrogen-strengthened stainless steels: Nitronic 20,32, 33, 40, 50, and 60 from Armco; 18-18 Plus and Marinaloy HNand 22 from Carpenter Technology; and SAF 2205 and 253MA fromSandvik. Nitrogen, unlike carbon, has the advantage of increasingstrength without markedly reducing ductility. Some of these alloysare twice as strong as the standard austenitics and provide betterresistance to certain environments. All are normal or higher than nor-mal in chromium content. Some are also normal or higher than nor-mal in nickel content, while others are low in nickel and, in the case

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of 18-18 Plus, nickel-free. Nitronic 20, a 23% chromium, 8 nickel, 2.5manganese alloy, combines high resistance to oxidation and sulfida-tion and was developed for engine exhaust valves. Unlike austeniticsin general, it is hardenable by heat treatment. Solution treating(2150°F, 1177°C), water quenching, and aging (1400°F, 760°C) providetensile strengths of 84,000 lb/in2 (579 MPa) yield and 142,000 lb/in2

(979 MPa) ultimate. Stainless steel SAF 2205, an extra-low-carbon(0.03%), 22 chromium, 5.5 nickel, 3 molybdenum alloy, is a ferritic-austenitic stainless steel alloy with high resistance to chloride- andhydrogen-sulfide-induced stress corrosion, pitting in chloride environ-ments, and intergranular corrosion in welded applications. Because oftheir superior corrosion resistance, such duplex stainless steels arealso called super duplex stainless steels. Besides SAF 2205, othersinclude stainless steels 2304, 3RE60, 255 or Ferralium 255, and2507. As a class, they contain 18 to 25% chromium, 5 to 7 nickel, 0 to4 molybdenum, and 0 to 0.3 nitrogen. The 2304 also contains as muchas 0.6% copper, and 255 has 2% copper. All are low in carbon: 0.03 or0.04%. The 2304 (23 chromium, 4 nickel, 0.1 nitrogen) is molybde-num-free, thus most economical. The 2205 (22 Cr, 5 Ni, 3 Mo, 0.17 N)is more corrosion resistant than 316 but less than the super-austenitics of 5 to 6% molybdenum. The 2507 (25Cr-7Ni-3.7Mo-0.27N) has excellent resistance to pitting in aggressive environments.

Another super duplex austenitic is the wrought and cast stainlesssteel Zeron 100, from Weir Materials in England. This 24 to 26%chromium, 6 to 8.5 nickel, 3 to 4 molybdenum alloy also contains 0.5to 1 tungsten and the same range of copper, as well as 0.2 to 0.3 nitro-gen. The wrought material has an ultimate tensile strength of109,000 lb/in2 (752 MPa), a tensile yield strength of 101,000 lb/in (696MPa), 25% elongation, and 28 maximum Rockwell C hardness. Thecast product is less strong (101,000 and 65,000 lb/in2, respectively)but equally ductile and hard. The stainless steel SuperDux 65 is aduplex grade from Nippon Yakin Kogyo, of Japan.

The specialty austenitic stainless steel AL-6X, of AlleghenyLudlum, is a low-carbon, 20% chromium, 24 nickel, 6 molybdenumalloy developed specifically for resistance to seawater pitting andcrevice corrosion, and has found wide use for seawater condensertubing. Stainless steel AL-6XN, with 0.22% nitrogen, is one ofabout a dozen alloys called super austenitic stainless steels,which are more highly alloyed than ordinary austenitic stainlesssteels. There are two major families: the 6% molybdenum group andthe high-nickel group. Besides AL-6XN, the 6% Mo group includesstainless steels 25-6 Mo, 1925 hMo, UR SB8, 254 SMO, and 654SMO. They contain 20 to 25% chromium, 18 to 25 nickel, 5.5 to 7.5molybdenum, 0.5 to 1.5 copper, 0.2 to 0.5 nitrogen, and 0.02 to 0.03carbon. They are considerably stronger than the ordinary austenitics

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without sacrificing ductility and toughness, have good resistance togeneral corrosion, high resistance to pitting and crevice corrosion inwet chloride environments, and adequate resistance to stress-corro-sion cracking in chloride environments. The high-Ni group includesstainless steels Alloy 20, Alloy 28, Alloy 31, Alloy 825, 20 Mo-4,and 20 Mo-6. They contain 31 to 42% nickel, 20 to 27 chromium, 2.5to 6.5 molybdenum, 1 to 3.5 copper, and 0.015 to 0.07 carbon. Alloy20 and 20 Mo-4 also have 0.7 and 0.3% columbium plus tantalum,respectively. Alloy 31 has 0.02% nitrogen, and Alloy 825 also has0.9% titanium. Alloy 20 and Alloy 825 have excellent resistance toaggressive mineral acids but are not especially resistant to wet chlo-ride environments. Alloy 31 and 20 Mo-6, the richest in molybdenum(6.5 and 5.9%, respectively), are appreciably more resistant to chlo-ride corrosion. Stainless steel Alloy 3, or stainless steel Nicrofer33, contains almost equivalent amounts of chromium, iron andnickel—33, 32, and 31%, respectively—plus 1.6 molybdenum, 0.6copper, and 0.4 nitrogen. It is noted for high resistance to acidic andalkaline solutions, mixtures of nitric and hydrofluoric acids, andstress corrosion.

Crucible Steel’s stainless steel 303CC is a low-sulfur, low-carbon,more machinable version of the standard alloy for screw-machineproducts used in beverage dispensers. The lower sulfur eliminatestaste and odor problems associated with the standard alloy in suchproducts, and the lower carbon compensates for the loss in machin-ability associated with the reduction in sulfur. Stainless steel317LM contains slightly more molybdenum than standard 317L andis used for flue-gas scrubbers and in the paper and textile industries.Stainless steel JS 777, a 21% chromium, 25 nickel, 4.5 molybdenumalloy from Jessop Steel, is a high-copper (2%) version of the company’sstainless steel JS 700 for greater resistance to sulfuric acid in scrub-bers and coal gasification and desulfurization systems. Sandvik’sstainless steel SANICRO 28 is an extra-low-carbon (0.02%) high-alloy (27 chromium, 31 nickel, 3.5 molybdenum, 1 copper) austeniticstainless for resistance to chlorides and free fluorides. It is said to beespecially resistant to chloride pitting, crevice corrosion, and inter-granular corrosion in welds. Stainless steel Cryotech 302, a wirealloy from A1-Tech Specialty Steel, is similar to standard 302 in com-position, but cooling to 320°F (196°C) prior to drawing in the 0 to50°F (18 to 10°C) range induces greater tensile strength [to 295,000lb/in2 (2,034 MPa)] than conventional wire drawing.

The specialty austenitic stainless steel 2RE10, from Sandvik, is24.5% chromium, 20.5 nickel grade, with extremely low carbon (0.015maximum) and impurity contents. Key features are excellent resistanceto nitric acid—better than 304L, 321, and 329; better intergranularcorrosion resistance than 304L; better pitting resistance than 304L

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and 329; and good weldability. Ultimate tensile strength ranges from73,000 to 98,000 lb/in2 (503 to 675 MPa), tensile yield strength is30,000 lb/in2 (210 MPa), and the elongation is 30 to 35%.

Stainless steel 20Cb-3, of Carpenter Technology, contains 20%chromium, 34 nickel, 3 to 4 copper, 2 to 3 molybdenum, and a smallamount of columbium for stabilization against loss of corrosion resis-tance due to intergranular attack in welding. It resists sulfuric acid,especially in high concentrations at high temperatures, as well asacetate solvents, boric acid, cadmium and ferrous sulfates, and zincchloride. Two other austenitics of this company are noted mainly forsuperior galling resistance in self-mated applications, general metal-to-metal wear resistance, and scale resistance at temperatures up to1800°F (982°C). Stainless steel Gall-Tough contains 15 to 18%chromium, 4 to 6 each of nickel and manganese, 3 to 4 silicon, 0.08 to0.2 nitrogen, and maximum amounts of 0.15 carbon, 0.04 phosphorus,and 0.04 sulfur. It is stronger and more oxidation-resistant than 304stainless and, depending on the environment, comparable in corrosionresistance. Annealed bar has an ultimate tensile strength of about161,000 lb/in2 (1,110 MPa), a tensile yield strength of 60,000 lb/in2

(414 MPa), and a Charpy V-notch impact strength of 240 ft lb (325J). At 800°F (427°C), the yield strength is 29,000 lb/in2 (200 MPa).Stainless steel Gall-Tough Plus has 16.5 to 21% chromium, 6 to 10nickel, 4 to 8 manganese, 2.5 to 4.5 silicon, 0.5 to 2.5 molybdenum,0.05 to 0.25 nitrogen, and maximum amounts of 0.15 carbon and 0.04each of phosphorus and sulfur. It is stronger than 316 stainless, withequivalent oxidation resistance and equivalent or superior corrosionresistance in chloride environments. Annealed bar has an ultimatetensile strength of 113,000 lb/in2 (783 MPa), a tensile yield strength of61,000 lb/in2 (423 MPa), and a Charpy V-notch impact strength of 298ft lb (404 J). At 800°F (427°C), the yield strength is 30,000 lb/in2

(208 MPa). Cold-drawn bar of Gall-Tough and Gall-Tough Plus ismuch stronger and less tough.

Allegheny Ludlum’s stainless steel AL-610 and AL-611 offer supe-rior corrosion resistance to high concentrations of nitric acid. They areweak in this regard in low and intermediate concentrations. The steelsare also known as high-silicon stainless steels. AL-610 contains 3.7to 4.3% silicon plus 17 to 18.5 chromium, 14 to 15.5 nickel, and, at themost, 2 manganese, 0.5 copper, 0.02 phosphorus, 0.02 sulfur, and 0.018carbon. AL-611 has 5 to 5.6 silicon, 17 to 18 chromium, 17 to 18 nickel,0.5 to 0.8 manganese, and maximum amounts of 0.35 copper, 0.05nitrogen, 0.03 phosphorus, 0.015 carbon, and 0.013 sulfur. Vacuummelting is used to reduce carbon and nitrogen to lower contents thanspecified to maximize resistance to high concentrations of nitric acid.

For heat resistance mainly is a series of austenitic iron-chromium-nickel alloys from Rolled Alloys: RA330 (43 iron, 35 nickel, 19

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chromium, 1.25 silicon, and 0.05 carbon); RA85H (61 iron, 18.5chromium, 14.5 nickel, 3.5 silicon, 1 aluminum, 0.8 manganese, and 0.2carbon); RA353 MA (37 iron, 35 nickel, 25 chromium, 1.5 silicon, 0.15nitrogen, 0.05 cerium, and 0.05 carbon); and RA253 MA (65 iron, 21chromium, 11 nickel, 1.7 silicon, 0.6 manganese, 0.17 nitrogen, 0.08carbon, and 0.04 cerium). RA330 is the workhorse alloy with resistanceto oxidation and carburization to 2200°F (1204°C). RA85H, with highsilicon content, resists sulfidizing environments and hot corrosion inwaste incineration. RA353 MA is oxidation resistant up to 2300°F(1260°C), and RA253 MA combines oxidation resistance to 2000°F(1093°C) with high creep-rupture strength.

The wrought ferritic stainless steels are magnetic and less ductilethan the austenitics. Although some can be hardened slightly by heattreatment, they are generally not hardenable by heat treatment. Allcontain at least 10.5% chromium, and although the standard alloysare nickel-free, small amounts of nickel are common in the nonstan-dard ones. Among the standard alloys, stainless steel 430 is the gen-eral-purpose alloy. It contains 16 to 18% chromium and a maximumof 0.12 carbon, 1 manganese, 1 silicon, 0.04 phosphorus, and 0.03 sul-fur. Stainless steels 430F and 430FSe, the “free-machining” ver-sions, contain more phosphorus (0.06% maximum) and sulfur (0.15minimum in 430F, 0.06 maximum in 430FSe). Also, 430FSe contains0.15% minimum selenium, and 0.6 molybdenum is an option for 430F.The other standard ferritics are stainless steels 405, 409, 429, 434,436, 442, and 446. Types 405 and 409 are the lowest in carbon (0.08%maximum) and chromium (11.5 to 14.5 and 10.5 to 11.75, respec-tively), the former containing 0.10 to 0.30 aluminum to prevent hard-ening on cooling from elevated temperatures, and the lattercontaining 0.75 maximum titanium. 429 is identical to 430 except forless chromium (14 to 16%) for better weldability. 434 and 436 areidentical to 430 except for 0.75 to 1.25 molybdenum in the former andthis amount of molybdenum plus 0.70 maximum columbium and tan-talum in the latter, these additives improving corrosion resistance inspecific environments. 442 to 446 are the highest in chromium (18 to23% and 23 to 27, respectively) for superior corrosion and oxidationresistance, and in carbon (0.20 maximum). Also, 446 contains moresilicon (1.50% maximum).

These standard alloys melt in the range of 2600 to 2790°F (1427 to1532°C), have specific heats of 0.11 to 0.12 Btu/(lb °F) [460 to 502J/(kg K)] thermal conductivities of 12 to 15.6 Btu/(ft h °F) [21 to27 W/(m K)] at 212°F (100°C), and electrical resistivities of 23 to 26 in (59 to 67 cm) at 70°F (21°C). In the annealed condition,tensile yield strengths range from 35,000 to 40,000 lb/in2 (241 to 276MPa) for 405 to as high as 60,000 lb/in2 (414 MPa) for 434, with ulti-mate strengths of 65,000 to 85,000 lb/in2 (448 to 586 MPa) and elon-

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gations of 20 to 33%. For 1% creep in 10,000 h at 1000°F (538°C), 430has a stress-rupture strength of 8,500 lb/in2 (59 MPa). Typical appli-cations include automotive trim and exhaust components, chemicalprocessing equipment, furnace hardware and heat-treating fixtures,turbine blades, and molds for glass.

There are many specialty wrought ferritic stainless steels.Crucible Stainless Steel’s Sea-Cure is a low-carbon titanium-stabi-lized alloy containing 26% chromium, 3 molybdenum, and 2.5 nickeldeveloped for seawater condenser tubing. A still-higher-chromium(29%) alloy for such applications is Allegheny Ludlum’s vacuum-induction-melted stainless steel 29Cr-4Mo, which also finds use inchemical and petroleum refining equipment. Both alloys are quiteresistant to chlorides. In stainless steel 29Cr-4Mo-2Ni alloy,another VIM product from Allegheny Ludlum, the nickel adds resis-tance to sulfuric acid. The nickel-bearing alloy is also stronger, 90,000lb/in2 (621 MPa) versus 64,000 lb/in2 (441 MPa) in terms of tensileyield strength, but somewhat less ductile and slightly less resistant tostress corrosion. Still another VIM ferritic alloy from this firm is the26Cr-1Mo alloy known as E-Brite. It is produced to carbon contentsof only 0.001 to 0.002% and low nitrogen levels (0.010%) and is notedfor high resistance to pitting and virtual immunity to stress corrosionin chloride and caustic media. Stainless steel 3CR12, a specialtyferritic of Cromweld Steels Ltd., contains 10.5 to 12% chromium andmaximum amounts of 1.5 nickel, 1.5 manganese, 1 silicon, 0.6 tita-nium, 0.04 phosphorus, 0.3 sulfur, 0.03 nitrogen, and 0.03 carbon.Tensile strengths are 67,000 lb/in2 (462 MPa) ultimate and 41,000lb/in2 (283 MPa) yield, with 20% elongation and good formability andweldability. Aluminized 409 stainless steel, from AK Steel, offersbarrier protection, galvanic protection, and better appearance thanthe ferritic stainless. It was developed for auto exhaust components.Also for such applications, Nippon Steel of Japan offers stainlesssteel YUS436S, a 17 chromium, 1.2 molybdenum, 1 titanium gradewith small amounts of silicon, carbon, and nitrogen.

The specialty ferritics also include two kinds of virtually nickel-freestainless steel 18Cr-2Mo alloys: (1) low-interstitial, titanium- and/orcolumbium-stabilized sheet alloys and (2) resulfurized free-machiningbar alloys. The low-interstitial type, also designated stainless steel444, is insensitive to intergranular corrosion after welding or exposureto high temperatures, more resistant than the austenitic 304 to chlo-ride pitting and crevice corrosion, and virtually immune to chloride-induced stress-corrosion cracking. Producers include AlleghenyLudlum, Crucible, and LTV Steel, and the alloy has been used forcatalytic converters on light trucks, solar-panel collector plates, bever-age storage and processing tanks, heat-treating equipment, and pro-cessing vessels for molten nonferrous metals. The free-machining bar

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alloys, such as stainless steel 182-FM from Carpenter Technologyand Uniloy 18-2FM from Armco, are similar in machinability to stan-dard 416 stainless steel (a martensitic alloy having improved machin-ability) but superior to 303 in resistance to pitting and stress corrosion.They are used for screw-machine products. Specialty ferritics fromKawasaki Steel of Japan are the 16% chromium stainless steelR430XT and the 18.5 chromium, 1.5 molybdenum stainless steelRSX-1. Carbon and nitrogen contents can range from 0.0005 to 0.03and 0.004 to 0.015, respectively.

Wrought martensitic stainless steels are also magnetic and, beinghardenable by heat treatment, provide high strength. Of those in thestainless steel 4XX series, 410, which contains 11.5 to 13.0%chromium, is the general-purpose alloy. The others—403, 414, 416,416Se, 420, 420F, 422, 431, 440A, and 440C—have similar (403, 414) ormore chromium, 16 to 18% in the 440s. Most are nickel-free or, as in thecase of 414, 422, and 431, low in nickel. Most of the alloys also containmolybdenum, usually less than 1%, plus the usual 1% or so maximum ofmanganese and silicon. Carbon content ranges from 0.15% maximum in403 through 416 and 416Se, to 0.60 to 0.75 in 440A, and as much as 1.20in 440C. 403 is the low-silicon (0.50% maximum) version of 410; 414 is anickel (1.25 to 2.50)-modified version for better corrosion resistance. 416and 416Se, which contain 12 to 14% chromium, also contain more thanthe usual sulfur or sulfur, phosphorus, and selenium to enhance machin-ability. 420 is richer in carbon for greater strength, and 420F has moresulfur and phosphorus for better machinability. 422, which contains thegreatest variety of alloying elements, has 0.20 to 0.25% carbon, 11 to 13chromium, low silicon (0.75 maximum), low phosphorus and sulfur(0.025 maximum), 0.5 to 1.0 nickel, 0.75 to 1.25 of both molybdenum andtungsten, and 0.15 to 0.3 vanadium. This composition is intended tomaximize toughness and strength at temperatures to 1200°F (649°C).431 is a higher-chromium (15 to 17%) nickel (1.25 to 2.50) alloy for bettercorrosion resistance. The high-carbon, high-chromium 440 alloys com-bine considerable corrosion resistance with maximum hardness. Thestainless steel 5XX series of wrought martensitic alloys—501, 501A,501B, 502, 503, and 504—contain less chromium, ranging from 4 to 6%in 501 and 502, to 8 to 10 in 501B and 504. All contain some molybde-num, usually less than 1%, and are nickel-free.

These steels are hardenable by heat treatment in a manner similarto that for alloy steels in general. Hardening temperatures range from1600 to 1950°F (871 to 1066°C), and subsequent tempering is per-formed at temperatures of 300 to 1400°F (149 to 760°C). Annealingtemperatures range from 1500 to 1650°F (816 to 899°C). For the 4XXalloys, Brinell hardness ranges from about 180 to 250 in the annealedcondition and to about 250 to 600 in the hardened and tempered con-dition. In general, 403, 410, and 416 are the least hard and the 440s

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the hardest in either condition. In general, their physical properties,such as melting range, specific heat, thermal conductivity, and electri-cal resistivity, are not markedly different than those of the ferriticstainless steels. Tensile strengths, however, after hardening and tem-pering, are far greater. Most of the 4XX alloys can provide yieldstrengths greater than 150,000 lb/in2 (1,034 MPa) and some, such asthe 440s, more than 250,000 lb/in2 (1,724 MPa). The martensiticstainless steels, however, are less machinable than the austenitic andferritic alloys, and they are also less weldable. Forging temperaturesrange from 1900 to 2250°F (1038 to 1232°C). Most of the alloys areavailable in a wide range of mill forms, and typical applicationsinclude turbine blades, springs, knife blades and cutlery, instruments,ball bearings, valves and pump parts, and heat exchangers.

Stainless steel Pyrowear 675, of Carpenter Technology, is an alter-native to 440C and carburizing alloy steels for gears and bearings. Adouble-vacuum-melted product, it contains 13% chromium, 5.4 cobalt,2.6 nickel, 1.8 molybdenum, 0.65 manganese, 0.6 vanadium, 0.4 silicon,and 0.07 carbon. It is as corrosion-resistant as 440C and can be carbur-ized to a case hardness of Rockwell C 60 while providing a tough core ofRockwell C 40. At this hardness the core has an ultimate tensilestrength of 185,000 lb/in2 (1,276 MPa), a tensile yield strength of143,000 lb/in2 (986 MPa), and 19% elongation. Its fracture toughness—140,000 to 150,000 lb/in2 in (154 to 165 MPa m)—is said to bebetter than that of any martensitic stainless steel. CarpenterTechnology’s BioDur TrimRite is a 13.5 to 15 chromium, 0.4 to 1molybdenum, 0.4 to 1 nickel, 0.15 to 0.3 carbon martensitic stainlesswith maximum amounts of 1 manganese, 1 silicon, 0.04 phosphorus,and 0.03 sulfur. Annealed bar has an ultimate tensile strength of 88,000lb/in2 (607 MPa), a tensile yield strength of 54,000 lb/in2 (372 MPa), 28%elongation, and a Rockwell B hardness of 88. Hardening and temperingincreases strengths to as high as 250,000 lb/in2 (1724 MPa) ultimateand 185,000 lb/in2 (1,276 MPa) yield and hardness up to 50 Rockwell C.The steel’s corrosion resistance in several environments is said to bebetter than that of 410, 420, and 440 stainless steels. Uses include vari-ous fasteners, cutlery, food-processing equipment, valves, gages, andmedical and surgical cutting and scraping tools.

Stainless steel DD400, of Minebea Co. of Japan, is used in theUnited States for bearing balls and races. This high-carbon (0.61%)steel contains 12.9% chromium, 0.67 manganese, 0.32 silicon, 0.24copper, 0.08 nickel, 0.008 molybdenum, and 0.007 aluminum. It issaid to provide superior performance to 440C due to the absence ofprimary carbides after quenching and tempering.

The wrought PH stainless steels, also called age-hardenablestainless steels, date back to the 1940s and the development ofStainless W by United States Steel Corp. Three basic types are now

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available: austenitic, semiaustenitic, and martensitic. Regardless ofthe type, the final hardening mechanism is precipitation hardening,brought about by small amounts of one or more alloying elements,such as aluminum, titanium, copper, and, sometimes, molybdenum.Their principal advantages are high strength, toughness, corrosionresistance, and relatively simple heat treatment.

Of the austenitic PH stainless steels, A-286 is the principalalloy. Developed by Allegheny Ludlum and also referred to as an iron-base superalloy, it contains about 15% chromium, 25 nickel, 2 tita-nium, 1.5 manganese, 1.3 molybdenum, 0.3 vanadium, 0.15aluminum, 0.05 carbon, and 0.005 boron. It is widely used for aircraftturbine parts and high-strength fasteners. Heat treatment [solutiontreating at 1800°F (981°C), water or oil quenching, aging at 1325 to1350°F (718 to 732°C) for 16 to 18 h and air cooling] provides an ulti-mate tensile strength of about 150,000 lb/in2 (1,034 MPa) and a ten-sile yield strength of about 100,000 lb/in2 (690 MPa), with 25%elongation and a Charpy impact strength of 64 ft lb (87 J). The alloyretains considerable strength at high temperatures. At 1200°F(649°C), for example, tensile yield strength is 88,000 lb/in2 (607 MPa).The alloy also has good weldability, and its corrosion resistance inmost environments is similar to that of 3XX stainless steels.

The semiaustenitic PH stainless steels are austenitic in theannealed or solution-treated condition and can be transformed to amartensitic structure by relatively simple thermal or thermomechani-cal treatments. They are available in all mill forms, although sheetand strip are the most common. True semiaustenitic PH stainlesssteels include Armco’s PH 14-8Mo, PH 15-7Mo, and 17-7PH.Allegheny Ludlum’s AM-350 and AM-355 are also so classified,although they are said not to truly have a precipitation-hardeningreaction. The Armco steels are lowest in carbon content (0.04% nomi-nally in PH 14-8Mo, 0.07 in the others). PH 14-8Mo also nominallycontains 15.1% chromium, 8.2 nickel, 2.2 molybdenum, 1.2 alu-minum, 0.02 manganese, 0.02 silicon, and 0.005 nitrogen. PH 15-7Mocontains 15.2% chromium, 7.1 nickel, 2.2 molybdenum, 1.2 alu-minum, 0.50 manganese, 0.30 silicon, and 0.04 nitrogen. 17-7PH issimilar to PH 15-7Mo except for 17% chromium and being molybdenum-free. AM-350 contains 16.5% chromium, 4.25 nickel,2.75 molybdenum, 0.75 manganese, 0.35 silicon, 0.10 nitrogen, and0.10 carbon. AM-355 has 15.5% chromium, 4.25 nickel, 2.75 molybde-num, 0.85 manganese, 0.35 silicon, 0.12 nitrogen, and 0.13 carbon. Inthe solution-heat-treated condition in which these steels are supplied,they are readily formable. They then can be strengthened to variousstrength levels by conditioning the austenite, transformation tomartensite, and precipitation hardening. One such procedure, for 17-7 PH, involves heating at 1400°F (760°C), air cooling to 60°F (16°C),

906 STAINLESS STEEL




then heating to 1050°F (565°C) and air cooling to room temperature.In their heat-treated conditions, these steels encompass tensile yieldstrengths ranging from about 180,000 lb/in2 (1,241 MPa) for AM-355to 260,000 lb/in2 (1,793 MPa) for PH 15-7Mo.

After solution treatment, the martensitic PH stainless steelsalways have a martensitic structure at room temperature. These steelsinclude the progenitor of the PH stainless steels, Stainless W, Armco’sPH 13-8Mo, 15-5 PH, and 17-4 PH, and Carpenter Technology’sCustom 455. Of these, PH 13-8Mo and Custom 455, which contain 11to 13% chromium and about 8 nickel plus small amounts of other alloy-ing elements, are the higher-strength alloys, providing tensile yieldstrengths of 210,000 lb/in2 (1,448 MPa) and 235,000 lb/in2 (1,620 MPa),respectively, in bar form after heat treatment. The other alloys rangefrom 15 to 17% in chromium and 4 to 6 in nickel, and typically have ten-sile yield strengths of 175,000 to 185,000 lb/in2 (1,207 to 1,276 MPa) inheat-treated bar form. They are used mainly in bar form and forgings,and only to a small extent in sheet. Age hardening, following high-tem-perature solution treating, is performed at 800 to 1250°F (427 to 677°C).A precipitation-hardening stainless steel developed by Indal Technologyof Canada contains 16% chromium, 4 nickel, and 4 copper. It has an ulti-mate tensile strength of 190,000 lb/in2 (1,310 MPa), tensile yieldstrength of 160,000 lb/in2 (1,103 MPa), 8% elongation, and 39 Rockwell Chardness. It is used to secure helicopters on ship decks. CarpenterTechnology’s stainless steel Custom 465, with 11 to 12.5 chromium,10.75 to 11.25 nickel, 1.5 to 1.8 titanium, and 0.75 to 1.25 molybdenum,is a low-carbon (0.02 maximum) martensitic stainless steel. In the peakaged condition (H900), ultimate and yield tensile strengths approach260,000 lb/in2 (1,793 MPa) and 240,000 lb/in2 (1,655 MPa), respectively,elongation is 12 to 13%, and the hardness is 50 Rockwell C. The CharpyV-notch impact strength of 4.5-in (114-mm) -diameter bar ranges from 35to 45 ft.lb (47 to 61 J), and general corrosion resistance approaches thatof 304 stainless. Golf-club-face inserts are one application.

The Duracorr stainless steel, from Bethlehem Lukens Plate, isa ferrite and tempered martensite alloy containing 11% chromium,1 nickel, 1.5 manganese, 0.7 silicon, 0.03 nitrogen, and 0.2 to 0.3carbon. Ultimate tensile strength is 66,700 lb/in2 (460 MPa), theyield strength is 40,600 lb/in (280 MPa), elongation 18%, andCharpy V-notch impact strength is 25 ft . lb (34 J). The steel is some-what superior in yield strength to 304 stainless at temperatures upto 800°F (427°C) but 304 is stronger at higher temperatures. Itsatmospheric corrosion resistance is not nearly as good as that of304 but it is substantially better than that of weathering and galva-nized steels.

Free-machining stainless steels are mostly austenitic types but,as already indicated, also include ferritic and martensitic types.

STAINLESS STEEL 907




Besides standard grades there are many specialty ones. In general,Project 70 and Project 7000 stainless steels are standard gradestailored for superior machinability. More-machinable grades fromUgine Stainless and Alloy contain the ternary oxide CaO-Al2O3-SiO2,which, for 303-type grades, increases cutting speed from about 1200ft/min (366 m/min) to 2000 to 2300 ft/min (610 to 701 m/min).

Cast stainless steels are divided into two classes: those intended pri-marily for uses requiring corrosion resistance and those intended mainlyfor uses requiring heat resistance. Both types are commonly known bythe designations of the Alloy Casting Institute of the Steel FoundersSociety of America, and these designations generally begin with the let-ter C for those used mainly for corrosion resistance and with the letter Hfor those used primarily for heat resistance. All are basically iron-chromium or iron-chromium-nickel alloys, although they may also con-tain several other alloying ingredients, notably molybdenum in theheat-resistant type, and molybdenum, copper, and/or other elements inthe corrosion-resistant type. The corrosion-resistant cast stainlesssteel type follows the general metallurgical classifications of thewrought stainless steels, that is, austenitic, ferritic, austenitic-ferritic,martensitic, and precipitation hardening. Specific alloys within each ofthese classifications are austenitic (CH–20, CK–20, CN–7M), ferritic(CB–30 and CC–50), austenitic-ferritic (CE–30, CF–3, CF–3A, CF–8,CF–8A, CF–20, CF–3M, CF–3MA, CF–8M, CF–8C, CF–16F, andCG–8M), martensitic (CA–15, CA–40, CA–15M, and CA–6NM), and pre-cipitation hardening (CB–7Cu and CD–4MCu). The chromium content ofthese alloys may be as little as 11% or as much as 30, depending on thealloy. The heat-resistant cast stainless steel types may contain as lit-tle as 9% chromium (Alloy HA), although most contain much greateramounts, as much as 32 in HL. Although nickel content rarely exceedschromium content in the corrosion-resistant type, it does in several heat-resistant types (HN, HP, HT, HU, HW, and HX). In fact, nickel is themajor ingredient in HU, HW, and HX. Several of the heat-resistant typescan be used at temperatures as high as 2100°F (1149°C). The castaustenitic stainless steel X-Cavalloy, developed by Ingersoll-DresserPump, contains 18% chromium, 15.5 manganese, 0.5 nickel, 0.5 silicon,0.25 nitrogen, and 0.1 carbon. It features outstanding resistance to cavi-tation erosion and is used for centrifugal water-pump impellers. Becauseof its low nickel content, however, the steel is susceptible to acid attack.

Diffused stainless steel is a sheet steel with a low-carbon ductilesteel core and a diffused chromium-iron alloy surface. It is producedfrom low-carbon steel by heating the sheets in a retort containing achromium compound, which diffuses into the metal at a temperatureof about 2000°F (1093°C). The chromium alloys with the steel, thealloy on the surface containing as much as 40% chromium, which

908 STAINLESS STEEL




tapers off to leave a ductile nonchromium core in the sheet. Blackstainless steel, for electronic applications, is produced by immersingsheet steel in a bath of molten potassium dichromate and sodiumdichromate. The steel has a shiny, black finish.

Stainless steel yarn made from the fibers is woven into stainlesssteel fabric that has good crease resistance and retains its physicalproperties to 800°F (427°C). The fiber may be blended with cotton orwool for static control, particularly for carpeting. Fibers of 316 or 347stainless steels are used in fiber metal, also known as Feltmetal,for noise reduction. NV Bekaert SA of Belgium makes 316L stainlesssteel fiber as fine as 79 in (2 m) for three-dimensional web struc-tures called Bekaert WB, which are used for coalescing, filtration,aerosol retention, and demisting. The web can be sintered to a solidfelt, known as Bekaert ST.

STARCH. A large group of natural carbohydrate compounds of theempirical formula (C6H10O5)x, occurring in grains, tubers, and fruits.The common cereal grains contain from 55 to 75% starch, and potatoescontain about 18%. Starches have a wide usage for foodstuffs, adhe-sives, textile and paper sizing, gelling agents, and fillers; in makingexplosives and many chemicals; and for making biodegradable deter-gents such as sodium tripolyphosphate. Starch is a basic need of all peo-ples and all industries. Much of it is employed in its natural form, but itis also easily converted to other forms, and more than 1,000 differentvarieties of starch are usually on the U.S. market at any one time.

Most of the commercial starch comes from corn, potatoes, and man-dioca. Starches from different plants have similar chemical reactions,but all have different granular structure, and the differences in sizeand shape of the grain have much to do with the physical properties.Cornstarch has a polygonal grain of simple structure. It is the chieffood starch in the western world, although sweet-potato starch isused where high gelatinization is desired, and tapioca starch is usedto give quick tack and high adhesion in glues. Tapioca starch hasrounded grains truncated on one side and is of lamellar structure. Itproduces gels of clarity and flexibility, and because it has no cerealflavor, it can be used directly for thickening foodstuffs. Rice starch ispolygonal and lamellar, and has very small particles. It makes anopaque stiff gel and is also valued as a dusting starch for bakeryproducts, although it is expensive for this purpose. White-potatostarch has conchoidal or ellipsoidal grains of lamellar structure.When cooked, it forms clear solutions easily controlled in viscosity,and gives tough, resilient films for coating paper and fabrics.Prolonged grinding of grain starches reduces the molecular chain,and the lower weight then gives greater solubility in cold water.

STARCH 909




Green fruits, especially bananas, often contain much starch, but theripening process changes the starch to sugars.

In general, starch is a white, amorphous powder having a specificgravity from 0.499 to 0.513. It is insoluble in cold water but can beconverted to soluble starch by treating with a dilute acid. Whencooked in water, starch produces an adhesive paste. Starch is easilydistinguished from dextrins as it gives a blue color with iodine whiledextrins give violet and red. The starch molecule is often described as achain of glucose units, with the adhesive waxy starches as those withcoiled chains. But starch is a complex member of the great group ofnatural plant compounds consisting of starches, sugars, and cellulose,and originally named carbohydrates because the molecular formulacould be written as Cn(H2O)x; but not all now-known carbohydrates canbe classified in this form, and many now-known acids and aldehydescan be indicated by this formula.

Starch can be fractionated into two polymers of high molecularweight. Amylose is a straight-chain fraction having high adhesiveproperties for coatings and sizings, and amylopectin is a branched-chain fraction best known as a suspending agent for food-stuffs. Amylose is chemically identical with cellulose, but the chainunits of the molecule have an alpha linkage and are coiled, while thecellulose molecule is rigid. It has a molecular weight of 150,000, whileamylopectin has a molecular weight above 1 million. The 1–4 alphalinkage of amylopectin with random branches at the 6-carbon positionmakes the material easily dispersible in cold water but resistant togelling. Amylopectin is thus best suited for thickening, but because itcan be combined and cross-linked with synthetic resins and is highlyresistant to deterioration, it is used with resins for water-resistantcoatings for paper and textiles.

Tapioca is the starch from the root of the large tuber Manihotutilissima, now grown in most tropical countries. It is called cassavain southern Asia, manioc in Brazil, mandioca in Paraguay, andyuca in Cuba. This perennial vegetatively propagated shrub was cul-tivated as far back as 2,500 years ago, and there is some indirect evi-dence that it has been grown for 4,000 years in the Americas. Itsfresh roots contain 30 to 40% dry matter and have a starch content ofapproximately 85% of the dry matter. It is used in enormous quanti-ties for food in some countries, and in some areas much is used for theproduction of alcohol. In the United States it is valued for adhesivesand coatings, and only a small proportion in globules and flakes,known as pearl tapioca, is used in foodstuffs. Gaplek, used for cat-tle feed in Asia, is not the starch, but is dried and sliced cassava root.Tapioca starch may be sold under trade names. Kreamgel, used as athickener for canned soups, sauces, and pastries, is refined tapiocathat gives clear solutions without imparting odor or flavor.

910 STARCH




Potato starch, produced from the common white potato,Solanum tuberosum, has been the most important starch in Europe,but in the United States it is usually more expensive than cornstarch.It forms heavier hot pastes than tapioca. It is also free of flavor and isused as a thickener in foods. It does not crystallize easily. Arogum, ofMorningstar-Paisley, Inc., is potato starch used to give tough, resilientcoatings on paper and textiles, and Arojel P is pregelatinized potatostarch used as a beater additive to improve the strength and scuffresistance of kraft paper. Sweet-potato starch is from the tuberOpomoea batata. An average of 10 lb (4.5 kg) of starch is produced perbushel. The root has poor shipping qualities, and the starch is expen-sive, but it has excellent colloidal qualities and gelatinizes completelyat 165°F (74°C). It is used in some foodstuffs. It has a pleasant, sweet-ish flavor, and in Latin countries great quantities are marketed in theform of a stiff gel as a dessert sweet known as dulce de batata.

Arrowroot starch is from the tubers of the Maranta arundinaceaof the West Indies. It is easily digested and is used in cookies andother food products, especially baby foods. Florida arrowroot isfrom Zamia floridana. East Indian arrowroot is from the plantCurcuma angustifolia, which belongs to the ginger family. Arrowrootfrom St. Vincent, used in instant-pudding mixes and icings, is mar-keted as a precooked powder of about 200 mesh. It swells in coldwater and does not add flavor.

The starches do not crystallize as sugar does, and they may beadded to some confections to minimize crystallization. They are alsoused as binders in candies and in tablet sugar, but any considerablequantity in such products is considered as an adulterant. Metabolismof starch in the human system requires conversion to sugars, and thetaking in of excessive quantities of uncooked starch is undesirable.Modified starches are starches with the molecule altered by chemi-cal treatment to give characteristics suitable for particular industrialrequirements. The modified starches and especially prepared starchesare usually sold under trade names. Superlose is amylose from corn-starch, and Auperlose is amylose from potato starch. Ramalin isamylopectin. Amylon, of National Starch & Chemicals Corp., is corn-starch containing 57% amylose, and Kosul is cornstarch high in amy-lopectin. Textaid, of the same company, is a modified starch whichreacts with water to form a grainy structure. It is used in commin-uted meat products to give a firm texture. The ColFlo thickeningagents, stable and soluble in frozen foods, are modified, waxy corn-starches, high in amylopectin. Pregelatinized starches arepre-heat-treated starches that require no cooking for use in dry foodmixes or adhesives. Snow Flake starch is a cornstarch of this type.

Wheat starch is a fine, white starch made by separating out thegluten of wheat flour by wash flotation. It is used in prepared mixes

STARCH 911




for foam-type cakes and pie crusts to improve texture, add volume,and reduce the amount of shortening needed. It replaces up to 30% ofthe wheat-flour content of the mix. Starbake starch, of Hercules, iswheat starch. Paygel, of General Mills, is also wheat starch, butalant starch, or inulin, (C6H10O5)6 H2O, is not a starch in the ordi-nary sense, but is an insoluble sugar which occurs as the reservepolysaccharide in many plants. It is obtained from the roots of theartichoke, Helianthus tuberosis, native to America but now grownwidely in Europe. Unlike starch, the molecule has fructose units heldin glucoside linkage, and hydrolysis converts it to fructose.

Starch acetate, or acetylated starch, is used for textile sizing, inadhesives, and for greaseproofing paper. The insertion of acetate radi-cals reduces the tendency of the molecular chains to cling together.The acetylated starches are gums which gelatinize at lower tempera-tures than starch, and produce stable, nonlumping pastes which givestrong, flexible films. Miralloid and Mira-Film, of A. E. Staley Mfg.Co., are acetylated cornstarches. Morgum is a hydroxyethyl ether-ized starch which gives high film strength in coatings. The Kofilmsof General Mills are acetylated cornstarches which give greaseproof,craze-resistant coatings on paper and textiles.

Laundry starches are usually ordinary starches, but silicone resinemulsions may be added to starches to permit higher ironing tempera-tures, improve slipperiness, and improve the hand of the starched fabric.The so-called permanent starches, for household use, that are notremoved by washing, are not starch, but are emulsions of polyvinylacetate. Oxidized starch, a resistant starch for coatings, is made by thechloro-oxidation of a starch solution. Sumstar 190 is a diallyl starchmade by acid oxidation of cornstarch. Small amounts of the powder addedto kraft, tissue, or toweling pulp increase the wet and dry strengths andthe folding endurance of the papers. An ammoniated starch called Q-Tac starch is cornstarch reacted with quaternary ammonium groups. Aless than 1% solution improves paper strength. Sulfonated starchesare used as dirt-suspending agents with detergents for cleaning textiles.Nu-Film is a starch of this type. Clear Flo starch is a modified starchcontaining a carboxyl group and a sulfonic acid group in the molecule. Ithas high hydrating capacity and gelatinizes sharply at low temperatures.It is used in adhesives and water paints. Cato starch is a carboxymethylstarch used in paper sizing to add strength. Dry Flo starch is modifiedto contain a hydrophobic radical, such as CH2, which makes the mate-rial insoluble in water but soluble in oils. It is used in paints.

Many enzymes hydrolyze starch to maltose, but some enzymes con-vert the starch to the hard, tough glucosides known as mannans,such as the mannose of the ivory nut. Phospho mannan, producedby the fermentation of starch, is such a material used in adhesives.

912 STARCH




Granular starch, used in enzyme conversion processing, is in dense,granular particles produced by flash drying. Easy-Enz starch issuch a starch. Cationic starch is a starch with the molecules of sta-ble negative polarity to give higher adhesion on the cellulose fibers ofpaper or textiles. Molding starch, for adding to sugar candies to givesharp molding characteristics, is starch containing an edible oil.

The phosphate starch of American Maize Products Co. is anorthophosphate ester of cornstarch, marketed in sodium salt form asa light-tan, dry powder. It has high thickening power and makes aclearer paste than cornstarch. It has superior water-binding proper-ties at low temperatures. Frozen foods made with it do not curdle orseparate when thawed, and canned foods thickened with the starchcan be stored for long periods without clouding. It is also used as abriquetting binder for charcoal.

Starch sponge is an edible starch in the form of a coarse-textured,porous, crispy, spongelike material, used for confections by impregnat-ing with chocolate or sweets. In crushed form it is added to candy orcookies. It is produced by freezing, thawing, and pressing starch paste.The freezing insolubilizes the starch so that no soluble starch goes offwhen the water is pressed out. Lycasin and Polysorb are hydro-genated starch hydrolysates produced by Roquette Corp. for food andfeed applications. Nitrostarch, or starch nitrate, C12H12O10(NO2)3, isa fine, white powder made by treating starch with mixed acid. It ishighly explosive and is used for blasting, as a military explosive, andin signal lights. Grenite is nitrostarch mixed with an oil binder foruse in grenades. Trojan explosive is a mixture of 40% nitrostarchwith ammonium and sodium nitrates and some inert material toreduce the sensitiveness. Sepol starch coagulants, of Grace Dearborn,are used to break emulsions in waste treatment of lubricating oils, sol-uble oils, and synthetic coolants, including oils containing dissolvedsolids and water.

STATUARY BRONZE. Copper alloys used for casting statues, plaques,and ornamental objects that require fine detail and a smooth, red-dish surface. Most of the famous large bronze statues of Europe con-tain from 87 to 90% copper, with varying amounts of tin, zinc, andlead. Early Greek statues contained from 9 to 11% tin with as muchas 5% lead added apparently to give greater fluidity for crisp details.A general average bronze will contain 90% copper, 6 tin, 3 zinc, and 1lead. Statuary bronze for cast plaques used in building constructioncontains 86% copper, 2 tin, 2 lead, 8 zinc, and 2 nickel. The nickelimproves fluidity and hardens and strengthens the alloy, and thelead promotes an oxidized finish on exposure. The statuary bronzeused for hardware has 83.5% copper, 4 lead, 2 tin, and 10 zinc.Ω

STATUARY BRONZE 913




STEARIC ACID. A hard, white, waxlike solid of compositionCH3(CH2)16COOH, obtained from animal and vegetable fats and oilsby splitting and distilling. The hard cattle fats are high in stearicacid, but other fats and oils contain varying amounts. It is also calledoctodecanoic acid, and it can be made by hydrogenation of oleicacid. Stearic acid has a specific gravity of 0.922 to 0.935 and a melt-ing point of about 130°F (54°C), and it is soluble in alcohol but insolu-ble in water. It is marketed in cakes, powder, and flakes. Emory3101-D is isostearic acid which has the solubility and physicalproperties of oleic acid while retaining the heat and oxidation stabil-ity of stearic acid. Pearl stearic acid is the material in free-flowingbead powder. The acid is used for making soaps, candles, paint driers,lubricating greases, and buffing compositions, and for compoundingin rubbers, cosmetics, and coatings.

Successive pressings remove liquid oils, thus raising the meltingpoint and giving a whiter, harder product of lower iodine value. Oleooil is a yellow oil obtained by cold-pressing the first-run cattle tallow.Tallow oil is the oil following the first two grades of oleo oil.Industrene 4518 is the single-pressed grade, available as a moltenliquid or in flakes, from Humko Chemical Div. of Witco Corp.Industrene 5016 is the double-pressed variety. Oleostearin, used fortreating leather, is the stearin remaining after extraction of the oils.

Stearin is the glyceride of stearic acid. Acetostearins are themonoglycerides acetylated with acetic anhydride. They are closelyrelated to fats, but are nongreasy and are plastic even at low temper-atures. The highly acetylated stearins melt below body temperatureand are edible. Acetostearins are used as plasticizers for waxes andsynthetic resins to improve low-temperature characteristics. Steariteis a trade name for synthetic stearic acid made by the hydrogena-tion of unsaturated animal and fish oils. It is used in rubber com-pounding, as it is more uniform than ordinary stearic acid. Hystrene,of Humko Chemical, is purified and hardened stearic acid in grades of70, 80, and 97% stearic acid, with the remainder palmitic acid, usedfor candles, cosmetics, and stearates. However, Hystrene 5016 is atriple-pressed oil. Intarvin is a synthetic edible fat made from stearicacid by converting it to margaric acid, or daturic acid,C16H33COOH, and then esterifying with glycerin. It is used as a fatfor diabetics as it does not undergo the beta oxidation to lose two car-bon atoms at a time and produce acetoacetic acid in the system as dothe even-carbon food acids.

Wilmar 272 is refined stearic acid in flake form for use in candlesand coatings. Hydrofol is a double- and triple-pressed rubber gradethat is also used in coatings and candles. It is produced by SherexChemical Co. Flexchem B is sodium stearate, NaC18H35O2, in the

914 STEARIC ACID




form of a water-soluble, white powder which is insoluble in oils. It isused as a bodying agent in cosmetic creams. Myvacet is an ace-tostearin used as an edible plastic coating for poultry, cheese, andfrozen fish and meats to prevent loss of the natural color and flavor. Itis a white, waxy solid with melting points from 99 to 109°F (37 to43°C), but it also comes as an oil with congealing point of 45°F (7°C) foruse as a release agent on bakery equipment. Alfol is a high-purity, syn-thetic, linear primary alcohol from Vista Chemical Co. A similar stearylalcohol, Adol, is from Sherex Chemical and is used as a chemical inter-mediate. Cachalot is a food-grade product of M. Michel and Co.

Stearin pitch is a brown-to-black by-product residue obtained inthe splitting and distillation of fats and oils in the manufacture ofsoaps, candles, and fatty acids. While the word stearin implies that itcontains only stearic acid, it usually comes from a variety of oils andhas mixed acids, and it may take the name of the oil, such as linseedpitch or palm pitch. It is used in varnishes and cold-molding compositions.

STEEL. Iron alloyed with small amounts of carbon, 2.5% maximum,but usually much less. The two broad categories are carbon steelsand alloy steels, but they are further classified in terms of composi-tion, deoxidation method, mill-finishing practice, product form, and/orprincipal characteristics. Carbon is the principal influencing elementin carbon steels, although manganese, phosphorus, and sulfur arealso present in small amounts, and these steels are further classifiedas low-carbon steels (up to 0.30% carbon), medium-carbon steels(0.30 to 0.60), and high-carbon steels (more than 0.60). The greaterthe amount of carbon, the greater the strength and hardness, and theless the ductility. Alloy steels are further classified as low-alloysteels, alloy steels, and high-alloy steels, those having as much as5% alloy content being the most widely used. The most common desig-nation systems for carbon and alloy steels are those of the AmericanIron and Steel Institute and the SAE, which follow a four- or five-digitnumbering system based on the key element or elements, with thelast two digits indicating carbon content in hundredths of a percent.

Plain carbon steels (with 1% maximum manganese) are desig-nated 10XX; resulfurized carbon steels, 11XX; resulfurized andrephosphorized carbon steels, 12XX; and plain carbon steels with 1 to1.65% manganese, 15XX. Alloy steels include manganese steels(13XX), nickel steels (23XX and 25XX), nickel-chromium steels (31XXto 34XX), molybdenum steels (40XX and 44XX), chromium-molybde-num steels (41XX), nickel-chromium-molybdenum steels (43XX,47XX, and 81XX to 98XX), nickel-molybdenum steels (46XX and48XX), chromium steels (50XX to 52XX), chromium-vanadium steels

STEEL 915




(61XX), tungsten-chromium steels (72XX), and silicon-manganesesteels (92XX). The letter B following the first two digits designatesboron steels, and the letter L leaded steels. The suffix H is used toindicate steels produced to specific hardenability requirements.High-strength, low-alloy steels are commonly identified by a 9XXdesignation of the SAE, where the last two digits indicate minimumtensile yield strength in 1,000 lb/in2 (6.9 MPa).

In contrast to rimmed steels, which are not deoxidized, killedsteels are deoxidized by the addition of deoxidizing elements, such asaluminum or silicon, in the ladle prior to ingot casting. Thus we havesuch terms as aluminum-killed steel. Deoxidation markedlyimproves the uniformity of the chemical composition and resultingmechanical properties of mill products. Semikilled steels are onlypartially deoxidized, thus intermediate in uniformity to rimmed andkilled steels. Capped steels have a low-carbon steel rim characteris-tic of rimmed-steel ingot and central uniformity more characteristic ofkilled-steel ingot, and are well suited for cold-forming operations.

Steels are also classified as air-melted, vacuum-melted, or vacuum-degassed. Air-melted steels are produced by conventional meltingmethods, such as open hearth, basic oxygen, and electric furnace.Vacuum-melted steels are produced by induction vacuum meltingand consumable electrode vacuum melting. Vacuum-degassedsteels are air-melted steels that are vacuum processed before solidifi-cation. Vacuum processing reduces gas content, nonmetallic inclu-sions, and center porosity and segregation. Such steels are morecostly, but have better ductility and impact and fatigue strengths.

Steel-mill products are reduced from ingot into such forms as blooms,billets, and slabs, which are then reduced to finished or semifinishedshape by hot-working operations. If the final product is produced by hotworking, the steel is known as hot-rolled steel. If the final product isshaped cold, the steel is known as cold-finished steel or, more specifi-cally, cold-rolled steel, or cold-drawn steel. Hot-rolled mill productsare usually limited to low- and medium-nonheat-treated carbon steels.They are the most economical steels, have good formability and weld-ability, and are widely used. Cold-finished steels, compared with hot-rolled products, have greater strength and hardness, better surfacefinish, and less ductility. Wrought steels are also classified in terms ofmill-product form, such as bar steels, sheet steels, and plate steels.Bar steel used to reinforce concrete is called rebar, a low-grade steelmade from melted steel scrap and often coated with epoxy for corro-sion protection. Fermar is a higher-quality more corrosion- andfatigue-resistant steel developed at the University of California,Berkeley. Containing less carbon, thus less carbides, it is less suscepti-ble to electrolytic corrosion on water contact.

Cast steels refer to those used for castings, and PM (powdermetal) steels refer to powder compositions used for PM parts. Steels

916 STEEL




are also known by their key characteristic from the standpoint ofapplication, such as electrical steels, corrosion-resistant stain-less steels, low-temperature steels, high-temperature steels,boiler steels, pressure-vessel steels, etc.

STEEL POWDER. Powder used mainly for the production of steel PMparts made by consolidating the powder under pressure and then sin-tering, and, to a limited extent, for steel-mill products, principallytool-steel bar products. For PM parts, the powder may be admixed forthe desired composition or prealloyed; that is, each powder particle isof the desired composition. For mill products, prealloyed powder isused primarily. Steel powder is widely used to make small to moder-ate-size PM parts, having compositions closely matching those ofwrought steels. Among the more common are carbon steels, coppersteels, nickel steels, nickel-molybdenum steels, and stainless steels.

Ancorsteel 41 AB, of Hoeganaes Corp., is a premixed, highly com-pressible, low-alloy steel powder containing 0.5% carbon, 0.9 man-ganese, 0.85 molybdenum, and 0.75 chromium. Formed parts areintended for surface hardening by carburizing, nitriding, carbonitrid-ing, or nitrocarburizing. Stainless Steel Plus, of the Specialty MetalsDivision of Ametek, are powders of 303L, 304L, or 316L stainlesssteels blended with 10% powder of 15 nickel, 8 tin and copper. Theyare said to provide greater corrosion resistance than conventionalstainless steel powders. Powders for injection-molding PM parts areoften of iron-nickel or stainless steel but of very fine particle size.

STEEL WOOL. Long, fine fibers of steel used for abrading, chiefly forcleaning utensils and for polishing. It is made from low-carbon wirethat has high tensile strength, usually having 0.10 to 0.20% carbonand 0.50 to 1 manganese. The wire is drawn over a track and shavedby a stationary knife bearing down on it, and it may be made in a con-tinuous piece as long as 100,000 ft (30,480 m). Steel wool usually hasthree edges but may have four or five, and strands of various types aremixed. There are nine standard grades of steel wool, the finest ofwhich has no fibers greater than 0.005 in (0.0027 cm) thick, the mostcommonly used grade having fibers that vary between 0.002 and 0.004in (0.006 and 0.010 cm). Steel wool comes in batts, or in flat ribbonform on spools usually 4 in (10 cm) wide. Stainless steel wool is alsomade, and copper wool is marketed for some cleaning operations.

STILLINGIA OIL. A drying oil obtained from the kernels of the seeds ofthe tree Stillingia sebifera, cultivated in China and the southernUnited States. The seeds contain about 23% of a light-yellow oilresembling linseed oil but of somewhat inferior drying power. The oilhas a specific gravity of 0.943 to 0.946 and iodine value of 160. It hasthe peculiar property of expanding with great force at the congealing

STILLINGIA OIL 917




point. Stillingia oil is edible, but deteriorates rapidly, becoming bitterin taste and disagreeable in odor. Stillingia tallow, also known asChinese vegetable tallow, is obtained by pressing from the coating,or mesocarp, of the seeds, yielding about 25 to 35% fat. Sometimesthe whole seed is crushed, producing a softer fat than the true tallow.The tallow contains palmitic and oleic acids and is used in soaps andfor mixing with other waxes. Some stillingia trees are grown in Texas.

STRIPPABLE COATINGS. Coatings that are applied for temporary pro-tection and can be readily removed. They are composed of such resinsas cellulosics, vinyl, acrylic, and polyethylene; they can be water-base,solvent-base, or hot-melt. The choice of base depends on the surface tobe protected. Water-base grades are neutral to plastic and paintedsurfaces, whereas solvent-base types affect those surfaces. Clear vinylstrippable coatings, perhaps the most widely used, are usuallyapplied by spraying in thicknesses of 0.03 to 0.04 in (0.08 to 0.10 cm).Acrylic strippable coatings impart a clear, high-gloss, high-strength, temporary film to metal parts. Polyethylene strip-pable coatings are relatively low-cost and can be used on almost allsurfaces except glass. Cellulosic strippable coatings are designedfor hot-dip application. Film thicknesses range widely and can go ashigh as 0.2 in (0.51 cm). The mineral oil often present in these coat-ings exudes and coats the metal surface to protect it from corrosionover long periods.

STRONTIUM. A metallic element of the alkaline group. It occurs inthe minerals strontianite, SrCO3, and celestite, SrSO4, and resem-bles barium in its properties and combinations, but is slightly harderand less reactive and is not as white in color. It has a specific gravityof 2.54 and a melting point of about 1418°F (770°C), and it decom-poses in water. The metal is obtained by electrolysis of the fused chlo-ride, and small amounts are used for doping semiconductors. Itscompounds have been used for deoxidizing nonferrous alloys, andwere used in Germany for desulfurizing steel. But the chief uses havebeen in signal flares to give a red light, and in hard, heat-resistantgreases. Strontium 90, produced atomically, is used in ship-decksigns as it emits no dangerous gamma rays. It gives a bright sign, andthe color can be varied with the content of zinc, but it is short-lived.Strontium is very reactive and used only in compounds.

Strontium nitrate is a yellowish-white, crystalline powder,Sr(NO3)2, produced by roasting and leaching celestite and treatingwith nitric acid. The specific gravity is 2.96, the melting point is1193°F (645°C), and it is soluble in water. It gives a bright, crimsonflame and is used in railway signal lights and in military flares. It is

918 STRIPPABLE COATINGS




also used as a source of oxygen. The strontium sulfate used as abrightening agent in paints is powdered celestite. The ore of NovaScotia contains 75% strontium sulfate. Strontium sulfide, SrS, usedin luminous paint, gives a blue-green glow, but it deteriorates rapidlyunless sealed in. Strontium carbonate, SrCO3, is used in pyrotech-nics, ceramics, and ceramic permanent magnets for small motors.Strontium hydrate, Sr(OH)2 8H2O, loses its water of crystalliza-tion at 212°F (100°C) and melts at 707°F (375°C). It is used in mak-ing lubricating greases and as a stabilizer in plastics. Strontiumfluoride is produced in single crystals for use as a laser material.When doped with samarium, it gives an output wavelength around25,600 nin (650 nm).

STYRAX. A grayish-brown, viscous, sticky, aromatic balsam obtainedfrom the small tree Liquidambar orientalis of Asia Minor. It is alsocalled Levant styrax. It is used in cough medicines and for skin dis-eases, as a fixative for heavy perfumes, and for flavoring tobacco andsoaps. American styrax is obtained by tapping the sweet gum, L.styraciflua, of Alabama, a tree producing 8 oz (0.2 kg) of gum per year.It is a brownish semisolid and has the same uses as Levant styrax. Itis shipped from Central America under the name liquidambar, andin the southern United States is called sweet gum and storax. Thegum is not present in large amounts in the wood, but its formation isinduced by cuts. Benzoin is another balsam obtained from severalspecies of Styrax trees. It is a highly aromatic solid with an odor likevanilla, and is used in medicine and in perfumes and incense.Sumatra benzoin is from the tree S. benzoin and comes in reddish-brown lumps or tears. In medicine it was originally calledgum Benjamin. Siam benzoin, from southern Asia, is from thetrees S. tonkinense and S. benzoides. It is in yellowish or brownishtears. The Sumatra benzoin contains cinnamic acid, while the Asiaticgum contains benzoic acid. Benzoic acid, or phenylformic acid,C6H5COOH, formerly produced from benzoin, is now made syntheti-cally from benzol and called carboxybenzene. It is a white, crys-talline solid melting at 252°F (122°C), soluble in water and in alcohol.It is used as a food preservative, as an antiseptic, for flavoringtobacco, as a weak acid mordant in printing textiles, and in the man-ufacture of dyestuffs, pharmaceuticals, and cosmetics. Because it ispoisonous, not more than 0.1% is used in food preserving in the formof its salt, benzoate of soda, or sodium benzoate, C6H5COONa,which is a white, crystalline powder. A potassium salt is also availablefrom Mallinckrodt, Inc. Sorbic acid, CH3CH:(CH)2:CHCOOH, a solidmelting at 273°F (134°C), occurs in unripe apples, but is made syn-thetically. As a preservative and antimold agent it is more effective

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than benzoic acid, is nontoxic, and is readily absorbed in the humansystem. It is used in cheese and other foods. Sorbistat is a food gradewith antimicrobial activity against yeast, mold, and bacteria fromAshland Chemical Co. For food preservation it is used in the form ofthe water-soluble salt potassium sorbate. In a concentration of0.2% it does not affect taste or aroma. Preservastat, a sorbic acidfrom Tri-K Industries, Inc., can be used at approximately 25% lowerlevels than potassium sorbate to achieve the same results. It is avail-able as a powder, as granules, or in crystal form. Anisic acid,CH3OC6H4COOH, used for pharmaceuticals, is the methyl ether ofhydroxybenzoic acid. It is produced synthetically from carbon tetra-chloride and phenol, and is a solid melting at 363°F (184°C). It is alsocalled methoxybenzoic acid, umbellic acid, and dragonic acid.

SUEDE. Also called napped leather. A soft-finished, chrome-tannedleather made from calf, kid, or cowhide splits, or from sheepskin. It isworked on a staking machine until it is soft and supple, and thenbuffed or polished on an abrasive wheel. It has a soft nap on the pol-ished side and may be dyed any color. Suede is used for shoe uppers,coats, hats, and pocketbooks, but is now largely imitated with syn-thetic fabrics. Artificial suede, or Izarine, of Atlas Powder Co., hasa base of rubber fabric. Fine cotton fibers dyed in colors are cementedto one side, and the underside of the sheet is beaten to make thefibers stand out until the cement hardens. The fabric looks and feelslike fine suede. Some suede is also made by chemical treatment ofsheepskins without staking. It has a delicate softness, but is not aswear-resistant as calfskin.

SUGAR. A colorless to white or brownish, crystalline, sweet materialproduced by evaporating and crystallizing the extracted juice of thesugarcane or the sugar beet. Refined sugar is practically puresucrose, C12H22O11, and in addition to being a sweetening agent formany foods it is a valuable carbohydrate food and a food preservative.When used with cooked fruits to make jams and jellies, it is both apreservative and an added food. Lack of sugar in the diet developsketosis, the disease of diabetics, and results in the wasting away ofmuscles, using up of reserve fats, and the production of poisonousketones. When the blood-sugar level is low, a feeling of hunger isinduced which may not be satisfied even by overeating. A smallamount of sugar curbs the appetite and obviates surplus eating ofproteins and fats that create obesity. Natural brown sugar containsabout 2% of the minerals found in the plant, calcium, iron, phospho-rus, magnesium, and potassium, and although these are valuable asfoods, they are lost in the refining process.

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Sugar is at present most valued as a food and for the production ofby-product alcohol from the residue molasses, but the sucrose mole-cule is a convenient starting point for the production of many chemi-cals. However, the production and distribution of sugar have beenhemmed in by restrictive laws based on its use for food. The sucrosemolecule has two complex rings, a glucosido and a fructose. It can beregarded as a type of fructosido-glucose, but the fructose in sucrosehas a different structure, a furanose, or five-ring form, instead of thepyranose, or six-ring structure, of ordinary fructose. Hydrolysis ofsucrose with acid gives dextrorotatory glucose and fructose, and themixture is called invert sugar. Numoline is a noncrystallizinginvert sugar made by hydrolyzing sucrose to split the molecule intolevulose and dextrose. It is used in confectionery and bakery prod-ucts. Oxidation of sucrose produces oxalic acid and saccharic acid,(HCOH)4(COOH)2, which can be reduced to adipic acid. Glycerin canbe made from sugar by hydrogenation to sorbitol and then splitting.Thus, because of the great versatility of the sucrose molecule, and theease with which the sugar can be grown, sugar is one of the mostvaluable chemical raw materials. Sucrose benzoate is a benzoicacid derivative of sucrose used as a plasticizer and modifier for syn-thetic resins for lacquers and inks.

Sugarcane, Saccharum officinarum, is a tropical plant, originatingin Asia and first brought to the Canary Islands in 1503 and thence tothe West Indies. The plant will not withstand frost, but can be grownin a few favored regions outside of the tropics such as Louisiana. It isnow grown on plantations in Cuba, Hawaii, Brazil, the Philippines,Indonesia, Puerto Rico, Peru, and many other countries. The cane orstalks of the plant are crushed to extract the juice, which is then con-centrated by boiling, crystallized, and clarified with activated carbonor other material. The yield of sugar in Hawaii is about 14 tons(12,698 kg) of raw sugar per acre (4,047 m2). Analysis of sugarcanegives an average of 13.4% sucrose by weight of cane. The average yieldby milling is 91% of the contained sucrose, but yields as high as 98.8%are obtained by diffusion extraction of the cut-cane chips.

The sugar beet is a white-rooted variety of the common beet, Betavulgaris, and grows in temperate climates. It is cut up and boiled toextract the juice, and the production and refining of the sugar areessentially the same as for cane sugar. There is no difference in thefinal product, although raffinose, or melitriose, C18H32O16, a taste-less trisaccharide, occurs in the sugar beet, and may not be com-pletely changed to sucrose by hydrolysis, so that a greater quantitymay sometimes be needed to obtain equal sweetening effect. The pectins and starches of the sugar beet are not extracted by theuse of the slicing and diffusion method.

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Refined commercial sugar contains 99.98% sucrose and is gradedby screening to crystal size. The best qualities are the larger crystalsfrom the first and second runs. The soft sugars are from further crys-tallizing, until the noncrystallizing brown sugars are reached. Rawsugar testing 96° by the polariscope is the grade used as a basis forraw-sugar quotations. Commercial sugar may have starch added. Theultrafine 6X confectioner’s sugar usually contains 4% cornstarchas a noncaking agent, and block sugars may contain starch as a bind-ing agent, but starch reduces the sweetening powder.

Cane sugar is the high-grade syrup or liquid sugar, whilemolasses is the heavy residual syrup left after the crystallization.Edible molasses is the yellow to brownish, light, purified residuesyrup. Blackstrap molasses is the final, inedible, unpurified residueheavy syrup, used for the production of ethyl alcohol. It contains 50 to60% sugar by weight, mostly sucrose but some glucose. A purifiedgrade which retains the minerals is marketed as an edible blackstrapmolasses.

Molasses powder, used for bakery products, is made by spray dry-ing. It is a free-flowing, noncaking powder. Liquid sugar, much usedin food manufacturing because it saves handling costs, comes in vari-ous liquid densities and in various degrees of invert. The liquid sug-ars are usually not pure sucrose, and are called multisugars. Forfood manufacturing the calcium and other minerals may be left in,and they then have a yellow color. Multisugars with 90% sucrose and10% levulose and dextrose crystallize in hard, aggregate clusters,desirable in some confections. Flo-Sweet is liquid sugar. Sucrodexis liquid sugar containing one-third dextrose and two-thirds sucrose,with a solubility of 72% compared with only 45 for dextrose and 67 forsucrose. Inverdex, for canning and for fountain syrups, is about 85%invert sugar and 15 dextrose. Amberdex, used for cakes and cookies,is an amber-colored 50–50 mixture of sucrose and dextrose with theedible materials left in. Caramel, used for flavoring and coloringfoodstuffs and liquors, has a deep-brown color and a characteristictaste. It is burnt sugar marketed as a liquid or powder.

The papelon of South America is solidified edible molasses. Gur isunrefined brown sugar of India, and the pilancillo of Mexico is unre-fined brown sugar. Treacle is an English name for edible molasses.The refuse from sugar cane, called bagasse, is used as fuel and formaking paper and insulating board. Beet pulp, after extraction ofthe juice, is marketed as cattle feed. Despite restrictive controls overthe world supply of sugar, much sucrose is being used in the produc-tion of chemical products. Nonionic detergents, which are odorless,biodegradable powders with low toxicity, are made by reactingsucrose with fatty acid esters of volatile alcohols. Allyl sucrose is usedas a shellac substitute. Sucrose acetate isobutyrate is available in

922 SUGAR




three grades: semisolid, in ethyl alcohol, in toluene. The pure chemi-cal is a clear, viscous liquid boiling at 550°F (288°C), used as a plasti-cizer in synthetic resins to improve extrusion and to give flexibilityand adhesiveness in coatings. As much as 70% is used in nitrocellu-lose to give tough, flexible melt coatings. Nitto ester is sucroseester made with sugar and stearic acid. It is used as a food additive.

A type of edible sugar syrup is also obtained from the juice of avariety of sorghum grass, Sorghum vulgare, native to South Africa,but now grown in the southern United States. The juice or syrup,called sorghum syrup, or sorgo syrup, is light in color, has a char-acteristic delicate flavor, and contains gums and starch, which pre-vent crystallization. It also contains other sugars besides sucrose, andconsiderable mineral salts of value as foods. The total sugar in thejuice is from 9 to 17%, varying with the age of the plant. It is used insome sections to replace sugar and is employed in some confectioneryto give a distinctive flavor.

Apple syrup, or apple honey, used as a sweetening agent in thefood industry, for curing hams, and as a substitute moistening agentfor tobacco, is made from cull apples. The reduced syrup is treated toremove the bitter calcium malate. It contains 75% solids of which 65%consists of the sugars levulose, dextrose, and sucrose. Palm sugar, orjaggary, is the evaporated sap of several varieties of palm, includingthe coconut and the palms from which kittool, gomuti, and palmyrafibers are obtained. The sap contains about 14% sugar. It is muchused in India and the Pacific Islands. The palm wine known asarrack is made by fermenting the juice, called taewak, of the flowerstems of the aren palm of Java. A liter (1.06 qt) of taewak yieldsabout 0.2 lb (0.09 kg) of brown palm sugar. Wood molasses is madeby concentrating and neutralizing the dilute sugar solution producedby pressure hydrolysis of wood chips using dilute sulfuric acid at hightemperature. The molasses has a slightly bitter taste, but is used forstock feed and for industrial purposes. Wood sugars contain xylose,CHO(HCOH)3CH2OH, which belongs to the great group of pentosansoccurring in plant life. They have the same general formula with dif-ferent numbers of the HCOH group. Oxidation converts them to therespective acid, as xylonic acid from xylose, or arabinic acid fromthe arabinose of gum arabic. They can also be converted to the lac-tones, and are related to the furanes, so that the wood sugars have awide utility for the production of chemicals.

Other plants yield sweetening agents, but few are of commercialimportance. The leaves of the caá heé, a small plant of Paraguay, areused locally for sweetening Paraguayan tea. The name, pronounced kah-áh aye-áye, means sweet herb, and it has a more intense sweeteningeffect than sugar. Miracle Fruit powder, of International Minerals andChemical Corp., is a complex protein-based chemical derived from the

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fruit pulp of the Agbayun shrub, Synsepalum dulcificum, of west Africa.It has a strong sweetening effect and a pleasant natural flavor. Stevia, apotent low-calorie sweetener from the leaf of the South American shrubStevi rebaudiana and also grown in China, is restricted to use as adietary supplement.

The 6-carbon sugar derivative known as glucoronic lactone, usedas an antiarthritic drug, is derived from dextrose. Amino sugar, orglucosamine, has an NH2 group in the molecule in place of the alphahydroxyl group of glucose. This sugar occurs in marine animals.

Synthetic sweetening agents of no food value are used in diabeticfoods and in dietetic foods for the treatment of obesity. Many of thesesynthetic sweeteners are toxic in excess and are cumulative in thehuman system. Thus, dietary foods that depend on the substitutionof chemicals in place of sugar should be taken only with caution andunder medical direction. Saccharin, produced from coal tar, is ben-zoic sulfinide, C6H4SO2NHCO. It is 450 times sweeter than sugarand has no food value, but it has a disagreeable aftertaste. It is awater-insoluble white powder, but its salts, sodium saccharin, andcalcium saccharin, are soluble in water and are 300 times sweeterthan sugar. Saccharin is also used as a pH indicator, and as a bright-ener in nickel-plating baths.

The cyclamates were widely used in beverages and diet foods,but are now recognized as toxic drugs and are restricted. Sodiumcyclohexylsulfamate, or sodium cyclamate, Na(C6H12NO3S)2 2H2O, is used in dietetic foods and in some soft drinks as it has nofood value. It is 30 times sweeter than sugar, but at the 25% sweet-ening level of sugar it has an undesirable aftertaste, and at thesugar-sweetness level the off-taste predominates. For both sugar-free and salt-free diets, the calcium salt calcium cyclamateis used. Sucaryl, of Abbott Laboratories, is sodium cyclamate, andCyclan, of Du Pont, is calcium cyclamate. Hexamic acid, a white,crystalline powder which is cycle hexylsulfamic acid, is used as asupplement sweetener and intensifier with the cyclamates and sac-charin. Aspartame, also known as Nutrasweet, is a low-caloriesweetener used alone or in combination with sugar or saccharin insome breakfast cereals, diet soft drinks, and other ready-mixed bev-erages. Peryllartine is the sweetest known substance, being 2,000times sweeter than sucrose. It is a complex aldehyde derived fromterpenylic acid, which occurs in combined forms in turpentine andmany essential oils.

A number of other artificial sweeteners are also being developed.Acesulfame-potassium, known as Sunette in the United States,is available in a table-top formula, Sweet-One, and as an ingredi-ent in chewing gum and dry beverage mixes. Produced by Hoechst

924 SUGAR




Celanese Corp., it is 200 times sweeter than sugar and slightlymore so than aspartame. But since acesulfame-potassium suffersfrom a slight aftertaste, it is usually mixed with other sweeteners;the combination works synergistically, with the mixture beingsweeter than either component. Xylitol is a naturally derivedsugar alcohol made from birch bark. It offers few benefits oversugar, since it is about as sweet and has the same number of calo-ries. Produced in Finland, it is marketed in the United States byAmerican Xyrofin primarily for specialty diet foods, such as for dia-betics and infants, in oral hygiene, and pharmaceutical products.Alitame, formed from the amino acids L-aspartic acid and D-ala-nine by Pfizer, Inc., is 2,000 times sweeter than sucrose, just asheat-stable, and has a shelf life up to 4 times that of aspartame.Sucralose, being developed by McNeil Specialty Products Co., is600 times sweeter than sugar, from which it is derived. Naturalthaumatin, a protein that is 5,000 times sweeter than sugar, isused mainly as a flavor enhancer. Isomalt, a modified sugar, is usedin chocolates and confectioneries in Europe and Asia, and is produced by West Germany’s Subungsmittel GmbH. It is also usedas a bulking agent with the highly sweet products. Lev-O-Cal is aleft-handed L-sugar that is less sweet and has fewer calories thanthe right-handed, or normal, sugar. Polydextrose is another low-calorie bulking agent.

SUGAR PINE. The common name of the wood of the Pinus lamber-tiana, a coniferous tree growing in California and Oregon. The treegrows ordinarily to a height of 150 to 175 ft (46 to 53 m) with a diam-eter of 4 to 5 ft (1.2 to 1.5 m). Occasional trees are more than 200 ft(61 m) in height and 12 ft (3.7 m) in diameter, and are often free oflimbs up to 75 ft (23 m) from the ground. It is the largest of thepines. Sugar pine is durable, has moderate strength and fairly evengrain, and is not subject to excessive shrinkage or warping. Becauseof the latter quality it has come into use to replace the scarcer east-ern pines for patterns. It does not darken on exposure as westernpine does. It is widely employed for construction work and for fac-tory lumber for doors, frames, boxes, and wooden articles. Sugarpine is classified into three standard classes of grades according tofreedom from knots and faults as select, commons, and factory, orshop. The selects are designated as Nos. 1 and 2 clear, C select, andD select. The commons are graded as Nos. 1, 2, 3, and 4; the factoryas No. 3 clear, No. 1 shop, No. 2 shop, and No. 3 shop. The shops arejudged with the idea that they will be cut up into small pieces, andare consequently classified by the area of clear cuttings that can beobtained.

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SULFAMIC ACID. A white, crystalline, odorless solid of compositionHSO3 NH2, very soluble in water, but only slightly soluble in alcohol.The melting point is 352°F (178°C). The acid is stronger than othersolid acids, approaching the strength of hydrochloric. It is used in bat-ing and tanning leather, giving a silky, tight grain in the leather. Animportant use is for cleaning boiler and heat-exchanger tubes. It con-verts the calcium carbonate scale to the water-soluble calcium sulfa-mate, which can then be flushed off and combined with sodiumchloride; it also converts the rust to ferric chloride and then to thewater-soluble iron sulfamate. Pettibone Chemicals offers high-puritygrades for bleaching paper pulp and textiles, organic synthesis, gas-liberating compositions, and as a catalyst for urea-formalde-hyde resins. Ammonium sulfamate is the ammonia salt of the acid,used as a cleanser and anodizer of metals, as a weed killer, and forflameproofing paper and textiles. Lead ammonium sulfamate,Pb(SO3NH2)2, used in lead plating, is very soluble in water and has highthrowing power. Aminoethylsulfamic acid, NH2CH2CH2OSO3H, isused for treating paper and textile fibers to increase wet strength andwater repellency. Tobias acid, used in making azo dyes, is naphthy-lamine sulfonic acid, NH2C10H6SO3H, in white needles decomposingat 446°F (230°C).

SULFONATED OIL. A fatty oil that has been treated with sulfuric acid,the excess acid being washed out and only the chemically combinedacid remaining. The oil is then neutralized with an alkali. Sulfonatedoils are water-soluble and are used in cutting oils and in fat liquors forleather finishing. Sulfonated castor oil is called Turkey red oil.Leatherlubric is the trade name of E. F. Houghton & Co. for sul-fonated sperm oil used for leather. Solcod is the sulfonated cod oil ofthe same company. Sulfonated stearin and sulfonated tallow arealso used in leather dressing. They are cream-colored pastes readilysoluble in hot water. Mahogany soap is a name for oil-soluble petro-leum sulfonates used as dispersing and wetting agents, corrosioninhibitors, emulsifiers, and to increase the oil absorption of mineralpigments in paints. Petronate is a petroleum sulfonate containing62% sulfonates, 35 mineral oil, and 3 water. Phosphorated oils, ortheir sulfonates, may be used instead of the sulfonates as emulsifyingagents or in treating textiles and leathers. They are more stable toalkalies. Phosoils are phosphorated vegetable oils. Aquasol, ofAmerican Cyanamid Co., is a sulfonated castor oil used as an emulsify-ing agent. Cream softener is a name used in the textile industry forsulfonated tallow.

SULFUR. One of the most useful of the elements, symbol S. Its occur-rence in nature is little more than 1% that of aluminum, but it is easy

926 SULFAMIC ACID




to extract and is relatively plentiful. In economics, it belongs to thegroup of “S” materials—salt, sulfur, steel, sugars, starches—whoseconsumption is a measure of the industrialization and the rate ofindustrial growth of a nation. Sulfur is obtained from volcanicdeposits in Sicily, Mexico, Chile, and Argentina, and along the GulfCoast in Louisiana, Texas, and Mexico it is obtained from greatunderground deposits in the cap rock above salt domes. Offshoredeposits worked in the Gulf of Mexico are 2,000 ft (610 m) under thebottom. Strict environmental laws are driving the production of sul-fur recovered as a by-product of various industrial operations. It isalso obtained by the distillation of iron pyrites, as a by-product of cop-per and other metal smelting, and from natural gas. The sterriexported from Sicily for making sulfuric acid is broken rock rich insulfur. Brimstone is a very ancient name still in popular use for solidsulfur, but the District Court of Texas has ruled that sulfur obtainedfrom gas is not subject to tax as brimstone.

Sulfur forms a crystalline mass of a pale-yellow color, with a Mohshardness of 1.5 to 2.5, a specific gravity of 2.05 to 2.09, and meltingpoint of 232°F (111°C). It forms a ruby vapor at about 780°F (416°C).When melted and cast, it forms amorphous sulfur with a specificgravity of 1.955. The tensile strength is 160 lb/in2 (1 MPa), and com-pressive strength is 3,300 lb/in2 (23 MPa). Since ancient times it hasbeen used as a lute for setting metals into stone. Sulfur also con-denses into light flakes known as flowers of sulfur, and the hydro-gen sulfide gas, H2S, separated from sour natural gas, yields asulfur powder. Flotation sulfur is a fine, free-flowing sulfur dustwith particle sizes less than 157 in (4 m), recovered in gas produc-tion from coal. Commercial crude Sicilian sulfur contains from 2 to11% of impurities and is sold in three grades. Refined sulfur is mar-keted in crystals, roll, or various grades of powder, and the Siciliansuperior grade is 99.5% pure. This is the grade used in rubber manu-facture. Crystex is a sulfur, 85% insoluble in carbon bisulfide, usedin rubber compounding. The sulfur powder of Electronic SpaceProducts, Inc., used for semiconductors, is 99.9999% pure.

Sulfur has twice the atomic weight of oxygen but has many similarproperties and has great affinity for most metals. It has six valenceelectrons, but also has valences of 2 and 4. The crystalline sulfur isorthorhombic, which converts to monoclinic crystals if cooled slowlyfrom 248°F (120°C). This form remains stable below 248°F. Whenmolten sulfur is cooled suddenly, it forms the amorphous sulfur whichhas a ring molecular structure and is plastic, but converts graduallyto the rhombic form. Sulfur has a wide variety of uses in all indus-tries. The biggest outlet is for sulfuric acid, mainly for producingphosphate fertilizers. Agri Sul, from Eagle-Picher Industries, Inc., isavailable in prilled form or as a water-degradable grade, as a source

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of elemental sulfur for correcting sulfur deficiencies in crops andgrasses. Newsulfur, from Tri-K Industries, Inc., is a nonirritatingvariety that can be mixed by hand with any kind of ingredient. It isused for making gunpowder and for vulcanizing rubber, but for mostuses it is employed in compounds, especially as sulfuric acid or sulfurdioxide. A vast number of so-called thio compounds have been pro-duced. The thio alcohols, or mercaptans, have an SH groupinstead of the OH of true alcohols, and they do not react as alcohols,but the thio esters are made directly from the mercaptans. Thionylchloride, SOCl2, a yellow liquid, is a typical compound used as asource of sulfur in synthesis. Most of the thio compounds have anoffensive odor. Vegetable sulfur does not contain sulfur, but is lyco-podium, a fine, yellow powder from the spores of the club moss, afernlike plant, Lycopodium clavatum, which grows in North Americaand Europe. It belongs to the group of lipochromes, or coloring mat-ter of plants related to lycopene and carotene.

Sulfur dioxide, or sulfurous acid anhydride, is a colorless gas ofcomposition SO2, used as a refrigerant, as a preservative, in bleaching,and for making other chemicals. It liquefies at about 14°F (10°C). Asa refrigerant it has a condensing pressure of 51.7 lb (23.5 kg) at 86°F(30°C). The gas is toxic and has a pungent, suffocating odor, so thatleaks are detected easily. It is corrosive to organic materials but doesnot attack copper or brass. The gas is soluble in water, forming sul-furous acid, H2SO3, a colorless liquid with suffocating fumes. Theacid form is the usual method of use of the gas for bleaching.

SULFURIC ACID. An oily, highly corrosive liquid of composition H2SO4,having a specific gravity of 1.841 and a boiling point of 626°F(330°C). It is miscible in water in all proportions, and the color is yel-lowish to brown according to the purity. It may be made by burningsulfur to the dioxide, oxidizing to the trioxide, and reacting withsteam to form the acid. It is a strong acid, oxidizing organic materi-als and most metals. Sulfuric acid is used for pickling and cleaningmetals, in electric batteries and plating baths, for making explosivesand fertilizers, and for many other purposes. In the metal industriesit is called dipping acid, and in the automotive trade it is calledbattery acid. Fuming sulfuric acid, or oleum, of 100% purity,was called Nordhausen acid. The grade of sulfuric acid known asoil of vitriol, or vitriol, is 66°Bé, or 93.2% acid. A 96% grade, calledParticulo, is available from General Chemical Co. Sulfur trioxide,or sulfuric anhydride, SO3, is the acid minus water. It is a colorlessliquid boiling at 115°F (46°C) and forms sulfuric acid when mixedwith water. It is used for sulfonation. Sulfan, of Allied-Signal Corp.,is sulfuric anhydride. Sulfodox is a liquid sulfur dioxide of high

928 SULFURIC ACID




purity from Specialty Products Corp. It is used for acidifying andbleaching. Chlorosulfonic acid, HClSO3, has equal amounts of sul-fur trioxide and hydrochloric acid, and is a vigorous dehydratingagent, used also in chlorosulfonating organic compounds. It has a spe-cific gravity of 1.752 and boils at 311°F (155°C). Mixed with sulfur tri-oxide, it has been called FS smoke for military smoke screens.

Niter cake, which is sodium acid sulfate, NaHSO4, or sodiumbisulfate, contains 30 to 35% available sulfuric acid and is used inhot solutions for pickling and cleaning metals. It comes in colorlesscrystals or white lumps, with a specific gravity of 2.435 and meltingpoint 572°F (300°C). Sodium sulfate, or Glauber’s salt, is a white,crystalline material of composition Na2SO4 10H2O, used in makingkraft paper, rayon, and glass. It was first produced from Hungarianspring water by Johann Glauber, and when obtained from mineralsprings, it is called crazy water crystals. The burkeite, sodiumsulfate–sodium bicarbonate double salt, which separates out ofSearles Lake brine, is used to produce sodium sulfate and otherchemicals as by-products. Salt cake, Na2SO4, is impure sodium sul-fate used in the cooking liquor in making paper pulp from wood. It isalso used in freezing mixtures. Synthetic salt cake, used for makingkraft pulp, is produced by sintering soda ash and sulfur. Chromecake is a greenish by-product salt cake which contains somechromium as an impurity. It is used in papermaking. Kaiseroda is aGerman name for salt cake of high purity obtained as a by-productfrom the production of magnesium chloride from potash minerals.Sodium sulfite, Na2SO3 or Na2SO3 7H2O, is a white to tan, crys-talline powder very soluble in water but nonhygroscopic. Santosite,of Monsanto, is a grade of sodium sulfite containing 93% sodium sul-fite with the balance chiefly sodium sulfate.

Sodium sulfide, Na2S, is a pink, flaky solid, used in tanneries fordehairing and in the manufacture of dyes and pigments. The commer-cial product contains 60 to 62% Na2S, 3.5 NaCl, and other salts, andthe balance water of crystallization. Sodium sulfhydrate, NaSH, isin lemon-yellow flakes. It has much less alkalinity than sodium sul-fide, and is used in tanneries in unhairing solutions and for makingthiourea and other chemicals. It contains 62.6% by weight of sulfurand is an economical material for sulfonating. Sodium dithionate,Na2S2O6 2H2O, is used in leather tanning, as an assist in textile dye-ing and printing, and for making other chemicals. It comes in trans-parent, prismatic crystals of bitter taste. Sodium thiosulfate,Na2S2O3 5H2O, known as hypo, is a white, crystalline compoundhaving a specific gravity of 1.73 and a melting point of 113°F (45°C).It is used in photography to fix films, plates, and papers. White vit-riol is zinc sulfate in colorless crystals soluble in water and melting

SULFURIC ACID 929




at 102°F (39°C). It is used for making zinc salts, as a mordant, forzinc plating, and as a preservative in adhesives.

SUMAC. The dried, ground leaves of the bush Rhus coriaria of Sicily,or R. typhina of the eastern United States, used for tanning leather.The Sicilian leaves contain up to 30% tannin, and the U.S. leaves upto 38%. It contains gallotannin and ellagitannin and gives a rapidtan. Sumac provides a light, strong leather of fine, soft grain and hasa bleaching action which can produce a white leather. It is used forbook and hatband leathers. Sumac grows profusely in the easternstates, but the gathering of the leaves is not organized commercially.

SUNFLOWER OIL. A pale-yellow drying oil with a pleasant odor andtaste obtained from the large seeds of the common sunflower plant,Helianthus annuus, of which there are many varieties. The plant isnative to Peru but is now grown in many parts of the world, particu-larly in California, Canada, Argentina, Chile, Uruguay, and Russia. Itrequires boron in the soil. The specific gravity of the oil is 0.925.Sunflower oil is used in varnish and soap manufacture or as a foodoil. Refined and unrefined grades, with trade name Trisun, are avail-able for these applications from SVO Enterprises. The by-productcake is used chiefly for cattle feed, but sunflower meal is alsoblended with wheat flour or cornmeal in foods. It is higher in vitaminB than soybean flour. Sunflower seeds are also used as poultry feed.Madia-seed oil is quite similar to sunflower oil and has the sameuses. It is obtained from the seeds of the plant Madia sativa, native toCalifornia. The seeds contain 35% oil, and the cold-pressed oil has apleasant taste. Watermelon-seed oil, produced in Senegal as bereffoil, is an edible oil similar to sunflower. It contains about 43%linoleic, 27 oleic, 19.5 stearic, and 5 palmitic acids.

The leaves of selected varieties of some species of sunflower containfrom 1 to 6% sunflower rubber and up to 8 resin. The H. occiden-talis, H. giganteus, H. maximiliani, and H. strumosus are cultivated inRussia both for the oil seed and for the rubber in the leaves. Theseperennials yield leaves up to 10 years. Another similar rubber-bearingplant of southern Russia is Asclepias cornuti, known as vatochnik. Itis a perennial, producing leaves for 10 to 15 years. The leaves yield 1to 6.5% rubber and large percentages of resin.

SUN HEMP. The bast fiber of the plant Crotalaria juncea. It is usedfor cordage and rope in place of jute, but is lighter in color and ismore flexible, stronger, and more durable than jute. It resembles truehemp, but is not as strong. It is more properly called sann hemp

930 SUMAC




from the Hindu word sann. It is also known as sunn fiber, Indianhemp, and Bombay hemp. The plant, which is a shrub, is cultivatedextensively in India. It grows to a height of about 8 ft (2.4 m), withslender branches yielding the fiber. The method of extraction is thesame as for true hemp. The best fibers are retained locally for makinginto cloth. It is also used in the United States for making cigarettepaper and for oakum. Madras hemp is from another species of thesame plant.

SUPERALLOYS. Iron-based, nickel-based, or cobalt-based alloys notedprimarily for high strength and oxidation and corrosion resistance athigh temperatures. Because of their excellent high-temperature per-formance, they are also known as high-temperature, high-strengthalloys. Their strength at high temperatures is usually measured interms of stress-rupture strength or creep resistance. For high-stressapplications, the iron-base alloys are generally limited to a maximumservice temperature of about 1200°F (649°C), whereas the nickel-andcobalt-based alloys are used at temperatures to about 2000°F (1093°C)and higher. In general, the nickel alloys are stronger than the cobaltalloys at temperatures below 2000°F, and the reverse is true at tem-peratures above 2000°F. Superalloys are probably best known for air-craft turbine applications, although they are also used in steam andindustrial turbines, nuclear power systems, and chemical and petro-leum processing equipment. A great variety of cast and wrought alloysare available, and in recent years, considerable attention has beenfocused on the use of powder-metallurgy techniques as a means ofattaining greater compositional uniformity and finer grain size.

The iron-based superalloys include solid-solution alloys and precipitation-hardening (PH), or precipitation-strengthened, alloys.Solid-solution types are alloyed primarily with nickel (20 to 36%) andchromium (16 to 21), although other elements are also present in lesseramounts. Superalloy 16-25-6, for example, the alloy designation indi-cating its chromium, nickel, and molybdenum contents, respectively,also contains small amounts of manganese (1.35%), silicon (0.7), nitro-gen (0.15), and carbon (0.06). Incoloy 800, 801, and 802, of Inco AlloysInternational, Inc., contain slightly less nickel and slightly morechromium with small amounts of titanium, aluminum, and carbon.Incoloy 803, of Inco, was developed for pyrolysis tubing in severe ethyl-ene furnaces and other petrochemical applications. It comprises 32 to37% nickel, 25 to 29 chromium, 0.15 to 0.6 aluminum, 0.15 to 0.6 tita-nium, 0.06 to 0.1 carbon, with maximum amounts of 1.5 manganese, 1silicon, 0.75 copper, and 0.015 sulfur, balance iron. The alloy has highresistance to oxidation and carburization. Protective scales, developed

SUPERALLOYS 931




by high-temperature exposure, provide the self-healing quality. Thealloy has an ultimate tensile strength of 88,000 lb/in2 (607 MPa) and50% elongation. At 1800°F (980°C), the tensile strength is 15,000 lb/in2

(103 MPa). N-155, or Multimet, an early sheet alloy, contains aboutequal amounts of chromium, nickel, and cobalt (20% each), plus 3molybdenum, 2.5 tungsten, 1 columbium, and small amounts of carbon,nitrogen, lanthanum, and zirconium. At 1350°F (732°C), this alloy hasa 1,000-h stress-rupture strength of about 24,000 lb/in2 (165 MPa).

PH iron-based superalloys provide greater strengthening by pre-cipitation of a nickel-aluminum-titanium phase. One such alloy,which may be the most well known of all iron-based superalloys, is A-286. It contains 26% nickel, 15 chromium, 2 titanium, 1.25 molyb-denum, 0.3 vanadium, 0.2 aluminum, 0.04 carbon, and 0.005 boron.At room temperature, it has a tensile yield strength of about 100,000lb/in2 (690 MPa) and a tensile modulus of 21.1 106 lb/in2 (145,000MPa). At 1200°F (649°C), tensile yield strength declines only slightly,to 88,000 lb/in2 (607 MPa), and its modulus is about the same orslightly greater. It has a 1,000-h stress-rupture strength of about21,000 lb/in2 (145 MPa) at 1350°F (732°C). Other PH iron-basedsuperalloys are Discoloy, Haynes 556 (whose chromium, nickel,cobalt, molybdenum, and tungsten contents are similar to those of N-155); Incoloy 903 and Pyromet CTX-1, which are virtuallychromium-free but high in nickel (37 to 38%) and cobalt (15 to 16);and V-57 and W-545, which contain about 14 chromium, 26 to 27nickel, about 3 titanium, 1 to 1.5 molybdenum, plus aluminum, car-bon, and boron. V-57 has a 1,000-h stress-rupture strength of about25,000 lb/in2 (172 MPa) at 1350°F and greater tensile strength, butsimilar ductility, than A-286 at room and elevated temperatures.

Nickel-based superalloys are solid-solution, precipitation-hard-ened, or oxide-dispersion-strengthened. All contain substantialamounts of chromium, 9 to 25%, which, combined with the nickel,accounts for their excellent high-temperature oxidation resistance.Other common alloying elements include molybdenum, tungsten,cobalt, iron, columbium, aluminum, and titanium. Typical solid-solu-tion alloys include Hastelloy X (22 to 23% chromium, 17 to 20 iron, 8 to 10 molybdenum, 0.5 to 2.5 cobalt, 2 aluminum, 0.2 to 1 tungsten,and 0.15 carbon); Inconel 600 (15.5 chromium, 8 iron, 0.25 coppermaximum, 0.08 carbon); and Inconel 601, 604, 617, and 615, of IncoAlloys International, Inc., the latter containing 21.5 chromium, 9 molybdenum, 3.6 columbium, 2.5 iron, 0.2 titanium, 0.2 aluminum,and 0.05 carbon. At 1350°F (732°C), wrought Hastelloy X (it is alsoavailable for castings) has a 1,000-h stress-rupture strength of about18,000 lb/in2 (124 MPa) and has high oxidation resistance at tempera-

932 SUPERALLOYS




tures to 2200°F (1204°C). Inconel 625 has a low-cycle (105) fatiguestrength of 110,000 to 120,000 lb/in2 (760 to 830 MPa). Inconel 625LCF has low carbon, silicon, and nitrogen contents to improve resis-tance to low-cycle fatigue. Inconel 725 is an age-hardenable versionof Inconel 625, providing comparable corrosion resistance but greaterstrength. Inconel 783 is an oxidation-resistant, low-expansion,nickel-cobalt-iron superalloy for aircraft turbine parts. RA333, fromRolled Alloys, contains 45 nickel; 25 chromium; 18 iron; 3 each ofcobalt, molybdenum, and tungsten; 1 silicon; and 0.05 carbon. Thealloy features good resistance to oxidation and carburization to2200°F (1200°C), has a tensile yield strength of 39,000 lb/in2 (269MPa), 47% elongation, and a creep-rupture strength of 4,300 lb/in2

(30 MPa) for 10,000 h at 1400°F (760°C).The precipitation-strengthened alloys, which are the most numer-

ous, contain aluminum and titanium for the precipitation of a secondstrengthening phase, the intermetallic Ni3(Al,Ti) known as gammaprime (′) or the intermetallic Ni3Cb known as gamma doubleprime (″), during heat treatment. One such alloy, Inconel X-750(15.5% chromium, 7 iron, 2.5 titanium, 1 columbium, 0.7 aluminum,0.25 copper maximum, and 0.04 carbon), has more than twice the ten-sile yield strength of Inconel 600 at room temperature and nearly 3times as much at 1400°F (760°C). Its 1,000-h stress-rupture strengthat 1400°F is in the range of 20,000 to 30,000 lb/in2 (138 to 207 MPa).Still great tensile yield strength at room and elevated temperaturesand a 25,000 lb/in2 (172 MPa) stress-rupture strength at 1400°F areprovided by Inconel 718 (19% chromium, 18.5 iron, 5.1 columbium, 3molybdenum, 0.9 titanium, 0.5 aluminum, 0.15 copper maximum,0.08 carbon maximum), a wrought alloy originally that also has beenused for castings. Inconel 718SPF is for superplastic forming, as thedesignation implies. A vacuum-induction-melted and electroslag-remelted alloy, it is produced to a fine grain size (ASTM 12), andreduced carbon and columbium contents to minimize carbide precipi-tation during forming. Gas pressure of only 300 lb/in2 (2 MPa) at1750°F (954°C) and low strain rates are sufficient to form complexshapes. Because of the low strain rates, forming cycles are long: 1 to 3h with mill-annealed sheet, which has an ultimate tensile strength of162,000 lb/in2 (1,117 MPa), a yield strength of 118,000 lb/in2 (814MPa), and 33% elongation. Aging increases the yield strength to192,000 lb/in2 (1,324 MPa). At 1200°F (649°C), the yield strength is160,000 lb/in2 (1,103 MPa). Among the strongest alloys in terms ofstress-rupture strength is the wrought or cast IN-100 (10%chromium, 15 cobalt, 5.5 aluminum, 4.7 titanium, 3 molybdenum, 1 vanadium, less than 0.6 iron, 0.15 carbon, 0.06 zirconium, 0.015

SUPERALLOYS 933




boron). Investment-cast, it provides a 1,000-h stress-rupture strengthof 75,000 lb/in2 (517 MPa) at 1400°F (760°C), 37,000 lb/in2 (255 MPa)at 1600°F (871°C), and 15,000 lb/in2 (103 MPa) at 1800°F (982°C).Other precipitation-strengthened wrought alloys include Astroloy;D-979; IN 102; Inconel 706 and 751; M252; Nimonic 80A, 90, 95,100, 105, 115, and 263; René 41, 95, and 100; Udimet 500, 520, 630,700, and 710; Unitemp AF2-1DA; and Waspaloy. Other cast alloys,mainly investment-cast, include B-1900; IN-738; IN-792; Inconel713C; M252; MAR-M 200, 246, 247, and 421; NX-188; René 77, 80,and 100; Udimet 500, 700, and 710; Waspaloy; and WAZ-20.

A few of the cast alloys, such as MAR-M 200, are used to producedirectionally solidified castings, that is, investment castings inwhich the grain runs only unidirectionally, as along the length of tur-bine blades. Eliminating transverse grains improves stress-ruptureproperties and fatigue resistance. Grain-free alloys, or single-crystalalloys, also have been cast, further improving high-temperaturecreep resistance. Developed mainly for aircraft-engine turbine blades,the first such alloys were pioneered by Pratt & Whitney Aircraft withPWA 1480 and also include AM1 and 3; CMSX-2, -3, and -6; ReneN4; RR2000; SRR 99; and SX 792. These alloys contain 8 to 12%chromium, 5 to 15 cobalt, 0 to 12 tantalum, 0 to 10 tungsten, 3.4 to6.0 aluminum, 1 to 4.7 titanium, 0 to 3 molybdenum, and, in somecases, small amounts of columbium, hafnium, and/or vanadium. Theyhave similar creep-rupture properties but differ in various other per-formance criteria and single-crystal castability. These alloys were fol-lowed with 3 to 6% rhenium alloys having less chromium (2 to 7) andother compositional changes. They include CMSX-4 and -10, PWA1484, SC 180, and Rene N5 and N6. Compared with rhenium-freeSRR 99, the 6 rhenium CMSX-10 (RR3000) increases 500-h creepstrength by 46% and 20,000-cycle fatigue strength by 59%.

At 1400°F (760°C), Cannon Muskegon’s CMSX-4 has a tensile yieldstrength of 140,000 lb/in2 (965 MPa), and it retains useful strength upto 2125°F (1163°C). Regarding powder-metallurgy techniques, empha-sis has been on the use of prealloyed powder made by rapid solidifi-cation techniques (RST) and mechanical alloying (MA), ahigh-energy milling process using attrition mills or special ball mills.Dispersion-strengthened nickel alloys are alloys strengthened bya dispersed oxide phase, such as thoria, which markedly increasesstrength at very high temperatures but only moderately so at inter-mediate elevated temperatures, thus limiting applications. TD-nickel, or thoria-dispersed nickel, was the first of such super-alloys, and it was subsequently modified with about 20% chromium,TD-NiCr, for greater oxidation resistance. MA 754, 758, and 6000E

934 SUPERALLOYS




alloys combine dispersion strengthening with yttria and gamma-prime strengthening. Alloys 754 and 758 are the same composition-ally except for 20 and 30 chromium, respectively. MA 6000 contains69% nickel, 15 chromium, 4.5 aluminum, 4 tungsten, 2.5 titanium, 2molybdenum, 2 tantalum, 1.1 yttria, 0.5 carbon, 0.15 zirconium, and0.01 boron. It provides high creep strength up to 2100°F (1150°C) and,in England, is used for solid blades of industrial gas turbines. Threepercent rhenium dispersion-strengthened alloys are roughly similarin composition to the 3% rhenium single-crystal alloys, although theycontain more hafnium (1.4 to 1.5) plus small amounts of grain-bound-ary-strengthening elements carbon, boron and zirconium. Thesealloys are PWA 1426, Rene 142, and CM 186 LC, and have similarcreep-rupture strength to the original “first generation” rhenium-freesingle-crystal alloys. CM 186 LC, however, does not require solutionheat treatment, thus reducing cost and avoiding recrystallization orincipient melting problems. In early production, casting yields haveapproached 90%.

Cobalt-based superalloys are for the most part solid-solutionalloys, which, when aged, are strengthened by precipitation of carbideor intermetallic phases. Most contain 20 to 25% chromium, substan-tial nickel and tungsten and/or molybdenum, and other elements,such as iron, columbium, aluminum, or titanium. One of the mostwell known, L-605, or Haynes 25, is mainly a wrought alloy, thoughalso used for castings. In wrought form, it contains 20% chromium, 15tungsten, 10 nickel, 3 iron, 1.5 manganese, and 0.1 carbon. At roomtemperature, it has a tensile yield strength of about 67,000 lb/in2 (462MPa), and at 1600°F (871°C) about 35,000 lb/in2 (241 MPa). Its 1,000-h stress-rupture strength at 1500°F (815°C) is 18,000 lb/in2 (124MPa). The more recent Haynes 188 (22% chromium, 22 nickel, 14.5tungsten, 3 iron, 1.5 manganese, 0.9 lanthanum, 0.35 silicon, and 0.1carbon), which was developed for aircraft-turbine sheet components,provides roughly similar strength and high oxidation resistance toabout 2000°F (1093°C). MP35N (35% nickel, 35 cobalt, 20 chromium,10 molybdenum) is a work-hardening alloy used mainly for high-temperature, corrosion-resistant fasteners. MP159 (25% nickel, 19 chromium, 9 iron, 7 molybdenum, 3 titanium, 0.2 aluminum) is awork and precipitation-hardening alloy for such fasteners. It has anultimate tensile strength of 260,000 lb/in2 (1,793 MPa), 205,000 lb/in2

(1,413 MPa) at 1100°F (593°C). Another alloy, S-816, contains equalamounts of chromium and nickel (20% each), equal amounts of molyb-denum, tungsten, columbium, and iron (4 each), and 0.38 carbon.Primarily a wrought alloy, though also used for castings, it has a1,000-h stress-rupture strength of 21,000 lb/in2 (145 MPa) at 1500°F

SUPERALLOYS 935




(815°C). Other casting alloys include AiResist 13, 213, and 215;Haynes 21 and 31, the latter also known as X-40; Haynes 151;J-1650; MAR-M 302, 322, 509, and 918; V-36; and W1-52. Theirchromium content ranges from 19% (AiResist 215) to 27 (Haynes 21),and some are nickel-free or low in nickel. Most contain substantialamounts of tungsten or tantalum, and various other alloying ele-ments. Among the strongest in terms of 1,000-h stress-rupturestrength at 1500°F are Haynes 21 and 31: 42,000 lb/in2 (290 MPa)and 51,000 lb/in2 (352 MPa), respectively.

SUPERBRONZE. A name applied to brasses containing both alu-minum and manganese. They are ordinarily high brasses with 2 to3% manganese and 1 to 6 aluminum, with sometimes also some iron.They have greatly increased strength and hardness over the originalbrasses, but the ductility is reduced and they are difficult to work andmachine. The early superbronze was known as Heusler alloy. Muntzmetal is also frequently modified with manganese, iron, and alu-minum. The alloys are used where high strength and corrosion resis-tance are required, and they are often marketed under trade names.The name superbronze is a shop term rather than a technical classifi-cation, and thus the name is often applied to any hard, high-strength,heat-treatable, copper-base alloy.

SUPERCONDUCTORS. Materials having no electrical resistivity, thusmaximum electrical conductivity, at or below a specific temperature,typically well below zero degrees. As long as the material remains ator below its superconducting temperature, strong magnetic fields canbe generated for use in many applications, including levitating trains.Until recently, temperatures approaching absolute zero [459°F(272°C)] were required. Some of the metals exhibiting superconduc-tivity at such temperatures are columbium, lead, iridium, mer-cury, tantalum, tin, and vanadium, as well as many alloys andcompounds. Alloys considered among the best commercially availableinclude columbium-tin, columbium-tantalum, columbium-tita-nium, and lead-molybdenum-sulfur. Columbium-titanium, in theform of flexible wire, is probably the most widely used. It has a super-conducting temperature of 441°F (263°C) and is generally limitedto magnetic fields below 80,000 G (8 T), particle accelerators beingone application. Magnets of greater strength—200,000 G (20 T)—have been made of columbium-tin. Columbium alloyed with tin andtitanium is used for magnets in magnetic resonance imaging andmagnetic-energy storage devices. Columbium-titanium wire coils,cooled by liquid helium to 452°F (269°C), have been proposed for

936 SUPERBRONZE




use in subway tunnels as a means of preventing voltage sags fromincreasing numbers of accelerating trains. Gallium-arsenide, grownunder certain conditions, is superconductive at 440°F (262°C) and,being compatible with semiconductor chips, could find electronicapplications. Using laser-deposited films of the mercury supercon-ductor HgBa2CaCu2O6 + gamma, IBM scientists have achieved acurrent density of about 6.45 105 A/in2 (105 A/cm2) at 279°F(173°C) in a magnetic field of 50 G (0.005 T) with the field at rightangle to the film plane, and about 108 A/cm2 at 10 kG (1 T) with thefield oriented parallel to the film plane.

In recent years various ceramic compounds have been found toexhibit superconductivity at higher temperatures. These includeYBa2Cu3O7x, also designated YBCO-123, with a superconductingtemperature of 294°F (181°C); Bi2Sr2CaCu2O10x, or BSCCO2212, also 294°F; Bi2Sr2Ca2Cu3O12x, or BSCCO 2223, 262°F(163°C); Tl2Ba2Ca2Cu3O12x, or TBCCO 2223, 235°F (148°C);and HgBa2Ca2Cu3O10x, or HBCCO 1223, 221°F (140°C). Theprincipal advantage of such “high-temperature” superconductors isthat liquid nitrogen [321°F (196°C)] instead of liquid helium[452°F (269°C)] could be used as the cooling medium. Potentialapplications include sonar transducers in submarines, high-powermotors for utilities and processing industries, power transmissioncables, magnetic bearings for energy-storage flywheels, electric cur-rent limiters, and electric current leads. A 3.28-ft (1-m) long conduc-tor made by American Superconductor Corp. of a BSCCO-typematerial can carry more than 2,300 A of direct current at 321°F, ormore than twice that typical of conventional underground copperconductors.

At Los Alamos National Laboratory, a flexible thick film of YBCO onmalleable nickel tape, first treated with a layer of cubic zirconia to tex-ture the surface, has carried a current density of 6.45 106 A/in2 (106

A/cm2) at liquid-nitrogen temperatures. And the critical currentdegraded only by a factor of 3 or 4 in a magnetic field typical of mag-netic resonance imaging machines. At Du Pont, a 2.6-ft (0.8-m) silver-encased BSCCO 2223 magnet surrounding a stainless-steel-wool-filledfilter can deliver 25,000 G (2.5 T) to remove magnetic contaminants inprocessing ores.

Despite the great interest in such ceramic superconductors, metalones have the advantage of being more ductile and, thus, more read-ily fabricated into flexible forms, such as wire. Here, too, recent devel-opments indicate increasing superconducting temperatures. AtAT&T’s Bell Laboratories, a composition of nickel, boron, yttrium, andcarbon has demonstrated superconductivity at 418°F (214°C). Also,

SUPERCONDUCTORS 937




the compound (NH3)4Na2CsC60, a carbon fullerene modified withalkali metals, has been found to change from insulator to supercon-ductor at 405°F (243°C).

SUPERCRITICAL FLUIDS. SCFs are fluids which, when compressedand heated above a critical pressure and temperature, have diffusionproperties similar to those of gases and densities similar to those ofliquids and, thus, are efficient solvents. Critical parameters (pres-sure, temperature, and density, respectively) for carbon dioxide are1,072 lb/in2 (7.4 MPa), 88°F (31°C), and 0.017 lb/in3 (471 kg/m3); forwater, 3,209 lb/in2 (22 MPa), 706°F (374°C), and 0.012 lb/in3 (332kg/m3); for hydrogen, 188 lb/in2 (1.3 MPa), 400°F (240°C), and0.0012 lb/in3 (33 kg/m3); for ammonia, 1,636 lb/in2 (11.3 MPa), 270°F(132°C), and 0.0085 lb/in3 (235 kg/m3); and for methyl alcohol, ormethanol, 1,154 lb/in2 (8 MPa), 464°F (240°C), and 0.01 lb/in3 (277kg/m3).

Current and potential applications for SCFs, especially carbon diox-ide and water, stem largely from regulatory pressures on ecology andsafety, and health trends. They were first used in the 1970s for decaf-feinating coffee and tea, replacing trichloroethylene and methylenechloride, have replaced ethylene chloride in spice extraction, and havebeen recently introduced for metal cleaning, deasphalting, and spraypainting without volatile organic compounds. Emerging or potentialuses for CO2 include ethanol purification; extraction of acetone fromantibiotics, fat and cholesterol from egg yolks, and vitamin E fromsoybean oil; and soil remediation. CO2, being nonpolar, is effective inremoving nonpolar contaminants from virtually any matrix and mayprove economical for on-site removal of organic soil contaminants thatdo not easily volatize. In pilot tests at the Westinghouse Hanfordnuclear site, CO2 at 6,000 lb/in2 (41 MPa) and 140°F (60°C) extractedmore than 95% of the diesel oil, polychlorinated biphenyls (PCBs),and bis (2-ethyl hexyl) phthalate.

Union Carbide’s Unicarb process uses a compressed gas, usuallyCO2, in the supercritical state to replace most of the solvent in con-ventional and high-solids topcoatings as well as in primers toreduce volatile organic compounds by as much as 80% and increasetransfer efficiency by reducing overspray. Concern about the knownhuman carcinogen perchloroethylene in dry-cleaning processes maydrive some 10% of the 30,000 such establishments in NorthAmerica to supercritical CO2 systems by the year 2005. In Japan,this SCF has been found to be one-third as costly and more energyefficient than the conventional thermal process for pasteurizing liq-uid foodstuffs. Also in Japan, this SCF with 1 to 3% tri-n-butyl

938 SUPERCRITICAL FLUIDS




phosphate has recovered 99% of the uranium, including variouslanthanides and actinides, from spent nuclear-reactor rods dissolvedin nitric acid. Moreover, the use of supercritical CO2 may prove econom-ical and/or energy efficient for the production of fluoropolymers,dimethyl carbonate, propylene carbonate, dimethyl terephthalate,and ethylene glycol. At 212°F (100°C) and 4,000 lb/in2 (27.6 MPa), ithas even achieved virtually 100% recovery of cedarwood oil fromjuniper-tree chips, about twice that of the usual steam distillationmethod. Both supercritical CO2 and nitrogen are used to make poly-ethylene and polypropylene foam products. A supercritical nitrogenis the usual gas in Trexel Corp.’s process for making MuCellmicrocellular foam.

Water at 3,400 lb/in2 (23 MPa) and 650 to 1100°F (343 to 593°C)has potential for treating various organic substances by supercriticaloxidation. Organic liquids and gases mix with the water and aretransformed into CO2 and water while inorganics dissolve onlyslightly, allowing them to concentrate and be recovered. Virtually allof the organics are destroyed. Potential abounds for waste treatmentat chemical, pulp and paper, and weapons plants. At a U.S. Navyfacility, a unit operating at 3,400 lb/in2 (23 MPa) and 650°F (343°C) isintended to destroy mixtures containing paint, oil, chlorinated sol-vents, PCBs, and other hazardous compounds. Supercritical wateroxidation is an economical alternative to incineration for destroyingessentially all pulp- and papermill-sludge organics, including PCBsand almost all dioxins and dibenzofurans. In tests at 3600 lb/in2 (24.8MPa) and 932°F (500°C) with oxygen as the oxidant, most of thematerial was converted to carbon dioxide and water, with inorganicash, acids, and salts. Compared with incineration, the SCF treatmenteliminates the need for smokestacks, emits practically no nitrousoxides, and excess heat can be used as process heat or to cogenerateelectricity.

Water is also in contention for soil remediation, having proved effec-tive in removing virtually all of the polycyclic aromatic hydrocarbons insoil. It is aimed at some 2,000 sites in the United States and Canadawhere town gas has been made from coal. KerforschungszentrumKarlsruhe of Germany is combining supercritical CO2 extraction witheither supercritical water oxidation or indirect electro-oxidation tocleanse metal-laden sludge at a glass-grinding facility and for treat-ment of halogenated organic wastestreams.

The drug developer Aphios Corp. has used supercritical carbondioxide, nitrogen, propane, and nonchlorinated freons in its processfor making protein nanoparticles for drug-delivery systems.Temperatures have ranged from 315 to 122°F (193°C to 50°C) and

SUPERCRITICAL FLUIDS 939




pressures from 1000 to 6000 lb/in2 (6.9 to 41 MPa), but are usuallyambient temperature and 3000 lb/in2 (20.7 MPa).

SUPERPOLYMERS. Many plastics developed in recent years canmaintain their mechanical, electrical, and chemical resistance proper-ties at temperatures over 400°F (213°C) for extended periods. Amongthese materials are polyimide, polysulfone, polyphenylene sul-fide, polyethersulfone, polyarylsulfone, novalac epoxy, aro-matic polyester, and polyamide-imide. In addition tohigh-temperature resistance, they have in common high strengthand modulus of elasticity, and excellent resistance to solvents, oils,and corrosive environments. They are also high in cost. Their majordisadvantage is their processing difficulty. Molding temperaturesand pressures are extremely high compared to conventional plastics.Some of them, including polyimide and aromatic polyester, are notmolded conventionally. Because they do not melt, the moldingprocess is more of a sintering operation. Thus, parts are oftenmolded by resin producers, such as Du Pont for its line of Vespelpolyimides, Furon Co. for its Meldin 3000 polyimides, and HoechstCelanese for its Celazole polybenzimidazole. One indication of thehigh-temperature resistance of the superpolymers is their glass transi-tion temperature of well over 500°F (260°C), as compared to less than350°F (177°C) for most conventional plastics. In the case of polyimides,the glass transition temperature is greater than 800°F (427°C), andthe material decomposes rather than softens when heated excessively.Aromatic polyester, a homopolymer also known as polyoxybenzoate,does not melt, but at 800°F (427°C) can be made to flow in a nonvis-cous manner similar to metals. Thus, filled and unfilled forms andparts can be made by hot sintering, high-velocity forging, and plasmaspraying. Notable properties are high thermal stability, good strengthat 600°F (316°C), high thermal conductivity, good wear resistance, andextra-high compressive strength. Aromatic polyesters have also beendeveloped for injection and compression molding. They have long-termthermal stability and a strength of 3,000 lb/in2 (21 MPa) at 550°F(288°C). At room temperature, polyimide is the stiffest of the groupwith a top modulus of elasticity of 7.5 106 lb/in2 (51,713 MPa), fol-lowed by polyphenylene sulfide with a modulus of 4.8 106 lb/in2

(33,096 MPa). Polyarylsulfone has the best impact resistance of thesuperpolymers with a notched impact strength of 5 ft lb/in (267 J/m).

PMR-15 is an addition-type thermosetting polyimide having a glasstransition temperature of about 644°F (340°C) and a maximum usetemperature of about 600°F (316°C). However, it is rather brittle andprone to microcracking and delamination in composites. AFR700B,

940 SUPERPOLYMERS




a toughened chemical modification developed by Air Forceresearchers, increases use temperature to about 700°F (370°C).Interleaving PMR-15 with Ciba Geigy’s thermoplastic polyimideMatramid 5218 in powder form reduces interply stress, thus delami-nation tendency. Aurum, a thermoplastic polyimide of Mitsui ToatsuChemicals of Japan, has a glass transition temperature of 482°F(250°C), a long-term continuous-use temperature of 350 to 446°F (177to 230°C), and a low thermal coefficient for dimensional stability. Ithas a tensile strength of 13,300 lb/in2 (92 MPa), a flexural strength of19,900 lb/in2 (137 MPa), a flexural modulus of 426,000 lb/in2 (2,937MPa), and a notched Izod impact strength of 1.6 ft . lb/in (85 J/m).Adding 30% carbon fiber more than doubles strengths, boosts modulusmore than sixfold, and improves impact strength to 2 ft . lb/in (107J/m). It also exhibits excellent performance as lubricated or nonlubri-cated bearings.

Polyetherimide, such as General Electric Plastics’ Ultem, is anamorphous thermoplastic that can be processed with conventionalthermoplastic processing equipment. Its continuous-use temperatureis 340°F (171°C), and its deflection temperature is 400°F (204°C) at264 lb/in2 (1.8 MPa). The polymer also has inherent flame resistancewithout the use of additives. This feature, along with its resistance tofood stains and cleaning agents, makes it suitable for aircraft panelsand seat component parts. Tensile strength ranges from 15,000 to24,000 lb/in2 (103 to 165 MPa). Flexural modulus is 480,000 lb/in2

(3,310 MPa). Polyamide-imide has a glass transition temperature of 527°F

(275°C), a tensile strength of 22,000 lb/in2 (152 MPa), a flexuralstrength of 34,900 lb/in2 (241 MPa), and heat-deflection temperatureof 532°F (278°C) at 264 lb/in2 (1.8 MPa). Torlon is such a material ofBP Amoco Polymers. Radel A, of this company, is polyethersulfone,Radel R is polyphenylsulfone, Udel is polysulfone, and Mindel is amodified polysulfone. Polyethersulfone combines substantial strengthretention and excellent dimensional stability at temperatures to390°F (200°C) and high creep resistance to 355°F (180°C). Ryton is apolyphenylene sulfide of Phillips Chemical Co., and Supec is onemade by General Electric Plastics.

Polyimide foam is a spongy, lightweight, flame-resistant materialthat resists ignition up to 800°F (427°C) and then only chars anddecomposes. Some formulations result in harder materials that canbe used as lightweight wallboard or floor panels while retaining fireresistance. Kapton is Du Pont’s polyimide film.

Aromatic polyketones are high-performance thermoplastics. Theyinclude polyaryletheretherketone (PAEEK), which has a glass

SUPERPOLYMERS 941




transition temperature of 289°F (143°C) and a melting point of 649°F(343°C). Produced by Victrex USA, it is known by the brand namePEEK; has a continuous use temperature of 500°F (260°C); is highlyresistant to wear, water, steam, and many chemicals; and requires noflame-retardant additives for a V-0 flammability rating at 0.057-in(1.45-mm) thickness. XC-2, of ICI Fiberite, is PAEEK prepreg tape forfilament winding applications. It has a maximum service tempera-ture of 600°F (316°C) and can be made in sheet form for compressionmolding. Carbon-fiber-reinforced XC-2, developed by EGC Corp., hasa tensile strength of 300,000 lb/in2 (2,069 MPa). Uses include cen-trifugal-pump rings and bushings in oil- and chemical-processingplants. Other aromatic polyketones include polyaryletherketone(PAEK), with a glass transition temperature of 310°F (154°C), andpolyaryletherketoneketone (PAEKK), with the same glass transi-tion temperature and a melting point of 635°F (335°C). There are alsovarious ketone-based copolymers.

SYCAMORE. The wood of the tree Acer pseudo-platanus, which isalso classified as a kind of maple, especially in England. The speciescut as sycamore in the United States is largely Platanus occidentalis.The wood has a close, firm, tough texture and is yellowish, with a reddish-brown heartwood. The light-colored sapwood is up to 3 in (8cm) thick in commercial trees. When quartered, the wood resemblesquartered oak. The density is about 38 lb/ft3 (609 kg/m3). The surfaceis lustrous and takes a fine polish. It is used for veneers, flooring, fur-niture, cooperage, and handles and rollers. Two other species grownin the southwest are California sycamore, P. racemosa, andArizona sycamore, P. wrightii.

TALC. A soft, friable mineral of fine colloidal particles with a soapyfeel. It is a hydrated magnesium silicate, 4SiO2 3MgO H2O,with a specific gravity of 2.8 and a Mohs hardness of 1. It is whitewhen pure, but may be colored gray, green, brown, or red with impu-rities. The pure white talc of Italy has been valued since ancienttimes for cosmetics. Talc is now used for cosmetics, for paper coatings,as a filler for paints and plastics, and for molding into electrical insu-lators, heater parts, and chemicalware. The massive block material,called steatite talc, is cut into electrical insulators. It is also calledlava talc. Talc dust is a superfine, 400-mesh powder from themilling of steatite talc. It has an oily feel and is used in cosmetics.The more impure block talcs are used for firebox linings and with-stand temperatures to 1700°F (927°C). Gritty varieties contain car-bonate minerals and are in the class of soapstones. Varietiescontaining lime are used for making porcelain.

942 SYCAMORE




Talc of specified purity and particle size is marketed under tradenames. Asbestine is a talc powder of 325 mesh for use as a filler.Ceramitalc is a talc powder used as a source of magnesia and toprevent crazing in ceramics. Sierra Fibrene is a California talcmilled to 400 mesh. It is white and has a platy structure, and as anextender in paints, it wets easily and promotes pigment dispersion.French chalk is a high-grade talc in massive block form used formarking. The mineral occurs in the United States in theAppalachian region from Vermont to Georgia. Georgia talc formaking crayons is mined in blocks. Attasorb and Permagel arefinely powdered, cream-colored, hydrated magnesium-aluminumsilicate from the mineral attapulgite, used for emulsifying and asa flatting agent and extender in paints. The material is also used instarch adhesives to improve shear strength. Attacote is the mater-ial in superfine particle size for use as an anticaking agent forhygroscopic chemicals. Veegum F, of R. T. Vanderbilt Co., is a fine,white, colloidal magnesium-aluminum silicate used as a suspendingagent for oils and waxes.

Cordierite is a talclike mineral with a high percentage of magne-sia used for refractory electronic parts. It is found sparsely in Norway,Finland, and Connecticut, usually in granite and gneiss, or in vitri-fied sandstones. When heated to 2624°F (1440°C), it is converted tosillimanite and glass. Synthetic cordierite is made by Muscle ShoalsElectrochemical Corp. by mixing pure silica, magnesia, and aluminain various proportions and stabilizing with calcia. It is marketed as apowder for producing refractory insulating parts. Extruded cordieriteserves as a substrate for the active catalyst metals in auto catalyticconverters.

Agalite is a mineral having the same composition as talc but witha less soapy feel. It is used as a filler in writing papers, but is morewearing on the paper rolls than talc. The talc of northern New York,known as rensselaerite, does not have the usual talc slip, and has afibrous nature. The hydrous aluminum silicate pyrophyllite, foundin California, is similar to talc but with the magnesium replaced byaluminum. In mixtures with talc for wall tile it eliminates crazing. Itis also substituted for talc as a filler for paints and paper. Thix, usedas a thickening agent in emulsion paints, in cosmetics, and in textilefinishes, is a refined, hydrous magnesium silicate marketed as a 200-mesh powder. It contains 56% silica, 26 magnesia, 2.8 calcia, 2.5Na2O, and 1.1 lithia.

Magnesium silicate, used as a filler in rubber and plastics, andalso as an alkaline bleaching agent for oils, waxes, and solvents, is awhite, water-insoluble powder of composition MgSiO4, having a pH of7.5 to 8.5. In the cosmetic trade it is known as talcum powder.

TALC 943




Magnesol, of Westvaco Chemical Co., is finely ground magnesiumsilicate. Brite-Sorb 30 is a synthetic magnesium silicate with highadsorption and filtering power. The magnesium trisilicate used inpharmaceuticals as an antacid is of extreme fineness, the superbulk-ing grade having 65% of the particles less than 197 in (5 m) in size.The material known as killas from the tin mines of Cornwall is aslaty schist. It is finely ground and used as talc.

TALL OIL. An oily, resinous liquid obtained as a by-product of the sul-fite paper-pulp mills. The alkali saponifies the acids, and the result-ing soap is skimmed off and treated with sulfuric acid to produce talloil. The name comes from the Swedish talloel, meaning pine oil. Thecrude oil is brown, but the refined oil is reddish yellow and nearlyodorless. It has a specific gravity of 0.98, flash point of 360°F (182°C),and acid number about 165. The oil from Florida paper mills contains41 to 45% rosin, 10 to 15 pitch, and the balance chiefly fatty acids.The fatty acids can be obtained separately by fractionating the crudewhole oil. The oil also contains up to 10% of the phytosterol sitos-terol, used in making the drug cortisone.

Tall oil is used in scouring soaps, asphalt emulsions, cutting oils,insecticides, animal dips, in making factice, and in plastics and paintoils. It is marketed in processed and concentrated form. Seecotol iscrude tall oil from Georgia-Pacific. Xtol, from the same firm, is a dis-tilled grade for use in surfactants, soaps, asphalt, alkyds, and as achemical intermediate. Acintol, from Arizona Chemical Co., contains60 to 68% fatty acids, 30 to 38 rosin acids, and has an acid value of185. Flextal is processed tall oil containing 60% rosin acids. Deter-gents are made by reacting tall oil with ethylene oxide. Saturatedalcohols are produced by high-pressure hydrogenation of tall oil. Thehigh linoleic acid content makes tall oil suitable for making dryingoils. Lumitol is a German vinyl plastic produced by reacting tall oilwith acetylene. It is used for coatings. Smithco RT, of Archer-Daniels-Midland Co., used for varnishes and paints, is refined tall oilesterified with glycerin. Smithco PE is tall oil esterified with pen-taerythritol. Ardex PE, of the same company, is a varnish oil thatdries quickly to a hard film, made by esterifying tall oil with pen-taerythritol. Sulfonated tall oil is used to replace sulfonated castoroil in coating mixes for paper to increase folding strength. Opoil is acrude tall oil, and Facoil is the refined oil with 60% fatty acid contentand low rosin acid content. Acolin, Acosix, and Aconon are gradesof refined tall oil. Pamac, of Hercules Inc., consists of tall oil monoba-sic fatty acids, used in resin coatings. Lytor 100 is a tall-oil rosin forpaper sizing, and for use as an adhesive and ink resin. It is producedby Georgia-Pacific.

944 TALL OIL




TALLOW. A general name for the heavy fats obtained from all parts ofthe bodies of sheep and cattle. The best grades of internal fats, orsuet, are used for edible purposes, but the external fats are employedfor lubricants, for mixing with waxes and vegetable fats, for soaps andcandles, and for producing chemicals. The tallows have the same gen-eral composition as lard, but are higher in the harder saturated acids,with about 51% of palmitic and stearic acids, and lower in oleic acid.The edible grades known as premier jus, prime, and edible are whiteto pale yellow, almost tasteless, and free from disagreeable odor; butthe nonedible or industrial tallows are yellow to brown unlessbleached. The best grade of industrial tallow is Packers No. 1.Peacock is an acidless grade for metalworking, lubricants and addi-tives, soaps, mold release, animal feed supplements, inks, and pig-ments; other premium and custom grades of Peacock are alsoproduced by George Pfau’s Sons Co. White grease, yellow grease,and brown grease may be hog fat, or they may be tallows with a titerbelow 104°F (40°C), the titer being the only commercial distinctionbetween tallow and fat. Tallow is thus all animal fat above 104°F titer.Beef tallow is used to produce stearic acid, for leather dressing, lubri-cating greases, and making soap. Mutton tallow contains less liquidfat and is harder, but it becomes rancid more easily. Tallow for indus-trial use is generally highly purified and chemically treated, and mar-keted under trade names. Adogen 442, of Archer-Daniels-MidlandCo., used as a softener for textiles, is a dimethyl hydrogenated tal-low. It comes as a nearly white, odorless paste in isopropanol andwater, and is dispersible in water or in organic solvents. Wax A, amixed hydrogenated tallow from Chemol Co., is a tallow glyceride.

TANNING AGENTS. Materials, known as tannins, used for the treat-ment of skins and hides to preserve the hide substance and make itresistant to decay. The tanned leather is then treated with fats orgreases to make it soft and pliable. Tannins may be natural or artifi-cial. The natural tannins are chiefly vegetable, but some mineral tan-ning agents are used. The vegetable tannins are divided into twocolor classes: the catechol and the pyrogallol. The catechol tanninsare cutch, quebracho, hemlock, larch, gambier, oak, and willow. Thepyrogallol tannins are gallnuts, sumac, myrobalans, chestnut, valo-nia, divi-divi, and algarobilla. Catechol tannin is distinguished by giv-ing a greenish-black precipitate with ferric salts; the pyrogalloltannins give a bluish-black precipitate. The catechol tannins, in gen-eral, produce leathers that are more resistant to heat and decay thanthe pyrogallols. Some tannins contain considerable coloring or dyematter, but the color that a tannin imparts to leather may be light-ened or darkened by raising or lowering the acidity of the tannin

TANNING AGENTS 945




bath. In the ink industry the catechol tannins are known as iron-greening, and the pyrogallol tannins as iron-bluing, and the latter areused for making writing inks. Catechol is also produced syntheticallyfrom coal tar. It is a water-soluble dihydric phenol in white, crys-talline granules known as ortho-dihydroxybenzene, C6H4(OH)2. Itis used in some inks and for making dyestuffs, medicinals, andantioxidants.

Alum tanning is an ancient process but was introduced in Europeonly about the year 1100, and the alum- and salt-tanned leather wascalled Hungary leather. Formaldehyde is also used as a tanningagent. Formaldehyde was patented as a tanning agent in 1898. Alater patent covered a rapid process of tanning sheepskins with alco-hol and formalin and then neutralizing in a solution of soda ash.Unlike vegetable agents, formaldehyde does not add weight to theskin. It is often used as a pretanning agent to lessen the astringencyof the vegetable tannin and increase its rate of diffusion. Melamineresins are used for tanning to give a leather that is white throughoutand does not yellow with age. Leather may also be tanned withchromic acid or chrome salts, which make the fibers insoluble andproduce a soft, strong leather. Chrome alum, sodium or potassiumdichromates, or products in which chromic acid has been used as anoxidizing agent may be used. Chrome tanning is rapid and is usedchiefly for light leathers. Tanolin is a name for basic chromiumchloride marketed in crystal form for use in the chrome tanning ofleather. Santotan KR is a trade name of Monsanto Co. for basicchromium sulfate, Cr2(SO4)2(OH)2, used as a one-bath chrome-tan-ning agent. This material is also used for treating magnesium-alloyparts to give a gray to black surface color. Panchrome, an Englishtanning agent, is a sulfur dioxide dichromate. Chromalin is a glyc-erin-reduced dichromate. Chrome-tanned leather is more resistant toheat than vegetable-tanned leathers, withstanding temperatures to200°F (93°C). Chrome tanning is used for shoe-upper leathers and forgloves, beltings, and packings. Iron-tanned leather is produced bypretanning with formaldehyde, then tanning with ferric salts andtrisodium phosphate, and neutralizing with a solution of phthalicanhydride and sodium carbonate. The leather is soft, will absorbmuch oil and grease, and is suitable for use where a pliable leather isdesired. Glutar aldehyde gives a soft, bulky leather suitable for gar-ments. It may be blended with chrome or vegetable tanning agents.

In tanning processes various supplementary materials may be usedto give special properties to the leathers. Glucose or starch may beused to make the leather more plump. Hydrochloric acid is used intwo-bath chrome tanning to enhance the feel and appearance of the

946 TANNING AGENTS




leather. Synthetic tannins, or syntans, are largely condensationproducts made by condensing sulfonated phenols with formaldehyde.Neradol D is such a syntan. Tansyn is the trade name of an Englishsyntan of this kind. Permanol, of Monsanto, is a sulfonic acid con-densation syntan in liquid form used to produce light-fast whiteleathers. The free sulfuric acid is completely neutralized. Syntans donot add weight to leather and are seldom used alone. They are mar-keted under trade names. Leukanol, of Rohm & Haas Co., has ableaching action and is used in combination with vegetable tannins tospeed up the tanning and to give a light-colored leather. Orotan, ofthe same company, is a sulfonated phenol formaldehyde which makesa good shoe leather when used alone. Tanigan, a German tannin, is acomplex condensation product produced from water pulp–mill liquorand formaldehyde or diphenyl methane.

TANTALUM. A white, lustrous metal, symbol Ta, resembling plat-inum. It is one of the most acid-resistant metals and is classified as anoble metal. Its specific gravity is 16.6, or about twice that of steel,and because of its high melting temperature [5425°F (2996°C)], it iscalled a refractory metal. In sheet form, it has a tensile yield strengthof 50,000 lb/in2 (345 MPa) and is quite ductile. At very high tempera-tures, however, it absorbs oxygen, hydrogen, and nitrogen andbecomes brittle. Its principal use is for electrolytic capacitors, butbecause of its resistance to many acids, including hydrochloric, nitric,and sulfuric, it is also widely used for chemical processing equipment.It is attacked, however, by hydrofluoric acid, halogen gases at ele-vated temperatures, fuming sulfuric acid, and strong alkalies.Because of its heat resistance, tantalum is also used for heat shields,heating elements, vacuum-furnace parts, and special aerospace andnuclear applications. It is also a common alloying element in superal-loys. The metal is used for prosthetic applications, and tantalumcarbide is used in cemented-carbide cutting tools. Tantalum alloys,including tungsten and tungsten-hafnium compositions, such as Ta-10W, T-111 (8% tungsten, 2 hafnium), and T-222 (9.6% tungsten,2.4 hafnium, and 0.01 carbon), are used for rocket-engine parts andspecial aerospace applications. The tensile yield strength of Ta-10W isabout 158,000 lb/in2 (1,089 MPa) at room temperature and 90,000lb/in2 (621 MPa) at 1600°F (871°C).

TANTALUM ORES. The most important ore of the metal tantalum istantalite. When pure, its composition is FeO Ta2O5, but theAmerican ore may contain only from 10 to 40% tantalic oxide,Ta2O5, and the Australian ore may contain as high as 70%. The ore is

TANTALUM ORES 947




marketed on the basis of 60% tantalic oxide content. Tantalite occursusually as a black, crystalline mineral with a specific gravity up to7.3. It often contains manganese, tin, titanium, and sometimes tung-sten; the tantalum may be replaced by columbium, which is similar toit. When the columbium content in the ore predominates, the mineralis called columbite. Tantalite also contains small amounts of germa-nium. The tantalite of the Congo usually contains tin. The ore fromthe Lukushi Basin contains 58% Ta2O5, 16.5 Cb2O5, 12.5 MnO, 4.5Fe2O3, and 1.6 SnO2, with some zirconium and titanium oxides. Tho-reaulite of that region contains 72 to 74% Ta2O5 and 20 to 22SnO2. Tantalum metal is produced from tantalite by dissolving in acidand separating the tantalum salts from the columbium by precipita-tion. The tantalum salts are reduced to powder metal, which is thencompressed into rods and sintered and rolled. The tantalite ore ofManitoba is embedded in pegmatite, and the crude ore contains about0.25% Ta2O5.

A tantalum ore that is abundant at Wodgina, western Australia, ismangano tantalite, which contains about 69% tantalic oxide, 15columbium pentoxide, Cb2O5, and 14 manganese protoxide, with alittle tin oxide. The specific gravity of the ore is 6.34. Microlite, anore found at Wodgina and in the McPhee Range of western Australia,contains 76% Ta2O5 and 4 to 7 Cb2O5. Tanteuxenite, another west-ern Australian ore, contains 24 to 47% Ta2O5 and 4 to 14 Cb2O5.Tapiolite, of Australia, contains 82% Ta2O5 and 2 Cb2O5. Euxenite,of Idaho, contains about 28% columbium-tantalum oxide. The mineralpyrochlore, of Canada, is composed of complex oxides of tantalum,columbium, sodium, and calcium, and the metal oxides are obtainedby acid extraction.

TAR. A black, solid mass obtained in the destructive distillation ofcoal, peat, wood, petroleum, or other organic material. When coal isheated to redness in an enclosed oven, it yields volatile products andthe residue coke. Upon cooling, the volatile matter, tar, and water aredeposited, leaving the coal gases free. Various types of coal yield tarsof different qualities and quantities, depending on the relative levelsof more than 200 compounds, including guaiacol, cresol, xylenol,crotonic acid, maltol, and ketones. Anthracite gives little tar, andcannel coal yields large quantities of low-gravity tar. In the manufac-ture of gas, the tar produced from bituminous coal is a viscous, blackliquid containing 20 to 30% free carbon, and is rich in benzene,toluene, naphthalene, and other aromatic compounds. In the drystate, this tar has a specific gravity of about 1.20. Tar is also producedas a by-product from coke ovens. Crowley Tar Products Co. sells bothcrude and refined coal tars under the trade name Impervotar.

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Coal tars are usually distilled to remove the light aromatics whichare used for making chemicals, and the residue tar, known astreated tar, or pitch, is employed for roofing, road making, and bitu-minous paints and waterproofing compounds. Coal-tar pitch is themost stable bituminous material for covering underground pipes, as abinder for electrodes used in aluminum smelting, and as an impreg-nant in refractories. Tarvia is the trade name of a refined coal tar,marketed by Barrett Co. in various grades. Tarmac is practically thesame material. Bituplastic, used for coating pipes and structures, isa refined coal-tar pitch that is odorless and quick-drying. Bituvia is aroad tar, produced in various grades by Reilly Tar & Chemical Corp.Coal-tar carbon amounts to about 32% of the original tar. It is mar-keted in lump form for chemical use. The fixed carbon content is 92.5to 95.6%, sulfur about 0.30, and volatile matter 3 to 6. Calcined car-bon, from coal tar, contains less than 0.5% sulfur and 0.5 volatilematter.

The lightest distillate of coal tar, benzene, is used as an automotivefuel. Coal-tar oils are used as solvents and plasticizers. They consistof various distillates or fractions up to semisolids. Tar oil from browncoal tars was used for diesel fuel oil by extracting the phenols withmethyl alcohol. Bardol B, of Allied Signal, is a clear, yellow, coal-tarfraction of specific gravity 1.0 to 1.04, used as a plasticizer for syn-thetic rubber, while Carbonex is a solid, black tar hydrocarbon inflake form used as a rubber plasticizer. The softening point is between205 and 220°F (96 and 104°C). Xylol is a water-white liquid of spe-cific gravity 0.860 to 0.870, distilling between 275 and 365°F (135 and185°C). It is a mixture of xylenes, which are dimethyl benzene,C6H4Me2.

Naphthalene and anthracene are among the distillates.Anthracene is a colorless, crystalline product of compositionC6H4:(C2H2):C6H4 and melting point 423°F (217°C) used for the pro-duction of dyes, resins, plasticizers, tanning agents, and inhibitors.Crystals of anthracene are used for scintillation counters for gamma-ray detection. Naphthalene oils, distilled from coke-oven tars, con-tain 65% naphthalene. They are used for making phthalic anhydride,ß-naphthol, and dye intermediates. Quinoline, called also ben-zazine and chinoline, is a liquid with a tar odor. It has a double-ringmolecular structure of empirical formula C9H7N, and it boils at 459°F(237°C). It is used for making antiseptics, pharmaceuticals, insecti-cides, and rubber accelerators.

Pine tar is a by-product in the distillation of pinewood. It is a vis-cous, black mass and is much used for roofing. Rosintene is a lightgrade from Crowley Tar Products Co. It is also sometimes called pitch,but pitch is the tar with the pine-tar oil removed, known as pine

TAR 949




pitch. Tarene is a dry, free-flowing powder made by absorbing pinetar into a synthetic hydrous calcium silicate which absorbs 4 times itsown weight of liquid tar. It is used for formulating with rubbers. Navypitch and ship pitch are names that refer to specification pine pitchfor marine use. It is medium hard to solid, has a specific gravity of1.08 to 1.10, has a melting point not less than 148°F (64°C), is com-pletely soluble in benzol, and has uniform black color, or red-brown inthin layers. Wood tar from the destructive distillation of other woodsis a dark-brown, viscous liquid used as a preservative, deriving thisproperty from its content of creosote. Stockholm tar, a name now outof commercial use, was a term employed in shipbuilding for the tarobtained from the crude distillation of pine stumps and roots.

TEA. The dried leaves of the shrubs Camellia sinensis and Theasinensis, grown chiefly in southern Asia, Japan, Sri Lanka, RussianCaucasia, and Indonesia but also in Peru and in Tanzania. The plantrequires a warm, subtropical, humid climate. Tea leaves are valuedfor making the beverage tea which contains the alkaloid caffeine andis stimulating. The leaves contain more caffeine than coffee berries,but the flavor is different. Like coffee, it also contains tannin, whichdissolves out when the tea leaves are steeped too long, and is anastringent. In well-prepared tea, the tannins have been oxidized tothe brown-and-red tannin which is not easily soluble and does notenter the properly steeped beverage to any great extent, although itgives the beverage its color. The flavor and aroma of tea dependlargely upon the age of the leaves when picked and the method of dry-ing. Green tea is made by drying the fresh leaves in the sun or artifi-cially, while black tea is made by first fermenting the leaves andthen drying. Rolling is done to break the leaves and release the juices.Epigallocatechin, a chemical found in green tea, is a strong antioxi-dant and anticarcinogen. The oolong tea of Taiwan is partly fer-mented and is intermediate between green and black. Pouchong teais graded by mixing oolong with aromatic flowers such as jasmine.Tea is also graded by the size and age of the leaf. Flowery orangepekoe is the smallest leaf, orange pekoe tea the second, then pekoe,pekoe souchong, and souchong. Tea also varies with varieties grownin different climates so that Japan tea, China tea, and Ceylon teahave different flavors.

Commercial tea is usually a blend of different varieties to give uni-formity under one trade name. The blending of tea is considered anart. Brick tea, made in China, is produced from coarse leaves andtwigs which have been fermented. They are mixed with tea dust,treated with rice water, and pressed into bricks. Cake tea, or puerh

950 TEA




tea, is produced in Yunnan. The leaves are panned, sun-dried,steamed, and pressed into circular cakes. Tablet tea is selected teadust pressed into small tablets. Tea waste is the final dust from thetea siftings, and it is used for the production of caffeine. Teaseed oil,or sasanqua oil, is from the seeds of another species of the tea plant,Thea sasanqua, of Asia. The seeds contain 58% of a pale-yellow oilwith a specific gravity of 0.916 used for lubrication, hair oil, soap, andpharmaceutical preparations. Paraguayan tea, or yerba maté,used in immense quantities as a beverage in Argentina, Paraguay,Brazil, and some other South American countries, consists of thedried, smoked leaves of the small evergreen tree Ilex paraguayensis,native to Paraguay and southern Brazil. The growing region is aboutthe upper Paraná River. It was an ancient beverage of the Indians,and cultivation began on a large scale under the early missionaries. Itcontains a higher percentage of caffeine than tea or coffee, 3.88%, butless tannin. The flavor of the steeped beverage is different from thatof tea. Cassine is a tealike beverage obtained from the twigs andleaves of two species of holly, Ilex cassine and I. vomitoria, found inthe southern United States from Virginia to Texas. It was calledYaupon by the Indians and used medicinally and in religious rites.During the Civil War it was used in the south as a tea substitute. Thebeverage has an odor similar to tea but has a dark color with a sharp,bitter taste. It contains caffeine, tannin, and essential oils.

TEAK. The wood of the tree Tectona grandis, of southern Asia. Itresembles oak in appearance, is strong and firm, and in England iscalled Indian oak. It contains an oil that gives it a pleasant odor andmakes it immune to the attacks of insects. It is used for boxes, chests,home furnishings, and woodwork on ships. The color is golden yellow,the grain is coarse and open, and the surface is greasy to the touch. Itis one of the most durable of woods, and also has small shrinkage.The density is 40 lb/ft3 (641 kg/m3). In Burma large plantations growteak for export. Trees grow to a height of 100 ft (30 m) with a diame-ter of 3 ft (0.9 m). The growth is slow, a 2-ft (0.6-m) tree averaging150 years of age. The wood marketed as African teak, known also asiroko, is from the tree Chlorophora excelsa, of west Africa, and isunlike true teak. It is a firm, strong wood with a brownish color and acoarse, open grain. The weight is somewhat less than that of teak,and it is harder to work, but it is resistant to decay and to termiteattack and is used in ship construction. Surinam teak is the wood ofthe tree Hymenea courbaril of the Guianas and the West Indies. It isalso called West Indian locust. The wood is dark brown, hard,heavy, and difficult to work. It is not very similar to teak and not as

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durable. Seacoast teak, or bua bua, is a hard, yellow, durable woodfrom species of the tree Guettarda of Malaya. Australian teak, fromNew South Wales, is from the tree Flindersia australis. It is yellowish-red, close-grained, and hard with an oily feel resemblingteak, but more difficult to work. In wood, of Burma, also called engteak, is from the tree Dipterocarpus tuberculatus, from which gurjunbalsam is obtained. The wood is reddish-brown, and it is not asdurable as teak. Two woods of Brazil are used for the same purposesas teak: the itaúba, Silvia itauba, a tree growing to a height of about75 ft (23 m) in the upland forests of the lower Amazon, and itaúbapreta, Oreodaphne bookeriana, a larger tree growing over a widerarea. The first is a greenish-yellow wood with compact texture andrough fiber, formerly prized for shipbuilding. The second resemblesteak more closely and is used for cabinetwork.

TELLURIUM. An elementary metal, symbol Te, obtained as a steel-gray powder of 99% purity by the reduction of tellurium oxide,or tellurite, TeO2, recovered from the residues of lead and copperrefineries. It is marketed in slabs and sticks and is sometimes knownas sylvanium. It occurs also with gold in Washington and Coloradoas gold telluride, AuTe2. The specific gravity is about 6.2 and themelting point 842°F (450°C). The chief uses are in lead to harden andtoughen the metal, and in rubber as an accelerator and toughener.Less than 0.1% tellurium in lead makes the metal more resistant tocorrosion and acids, and gives a finer grain structure and higherendurance limit. Tellurium-lead pipe, with less than 0.1% tellurium,has a 75% greater resistance to hydraulic pressure than plain lead. Atellurium lead, patented in England, contains 0.05% tellurium and6 antimony. Tellurium copper (C14500, C14510, and C14520) is afree-machining copper containing 0.3 to 0.7% tellurium. It machines25% more easily than free-cutting brass. The tensile strength,annealed, is 30,000 lb/in2 (207 MPa), and the electric conductivity is98% that of copper. A tellurium bronze containing 1% tellurium and1.5 tin has a tensile strength, annealed, of 40,000 lb/in2 (276 MPa),and is free-machining. Tellurium is used in small amounts in somesteels to make them free-machining without making the steel hot-short, as do increased amounts of sulfur. But tellurium is objec-tionable for this purpose because inhalation of dust or fumes by work-ers causes garlic breath for days after exposure, although thematerial is not toxic. As a secondary vulcanizing agent with sulfur inrubber, tellurium in very small proportions, 0.5 to 1%, increases thetensile strength and aging qualities of the rubber. It is not as strongan accelerator as selenium, but gives greater resistance to the rubber.

952 TELLURIUM




Telloy is the trade name of R. T. Vanderbilt Co. for tellurium pow-der ground very fine for rubber compounding.

TERNEPLATE. Sheet or plate steel coated by hot-dip processes with athin layer of lead containing 3 to 15% tin. Terne means dull and refersto the color of the coating as compared with bright tinplate. The coat-ing, intended to enhance corrosion resistance primarily, also improvesformability and solderability. Because of the toxicity of lead, however,special precautions are required in fabrication operations. The termsshort terne and long terne pertain to plate products and sheetproducts, respectively. Standard coating-thickness designations forsheet products range from LT10 (no minimum) to LT110 [1.10 oz/ft2

(336 g/m2)] total weight both sides based on a triple-spot test.Automobile gasoline-fuel tanks have been the major application,although terneplate also has been used for fuel tanks of lawn mowersand outboard marine motors as well as for roofing and building con-struction, caskets, and other applications.

TERRA COTTA. A general English term applied to fired, unglazed,yellow, and red clay wares; in the United States it refers particularlyto the red-and-brown, square and hexagonal tiles made from commonbrick clay, always containing iron. Some special terra cottas arenearly white, while for special architectural work other shades areobtained. The clays are washed, and only very fine sands are mixedwith them in order to secure a fine, open texture and smooth surface.Terra cotta is used for roofing and for tile floors, for hollow buildingblocks, and in decorative construction work. Good, well-burned terracotta is less than 1.5 in (3.8 cm) thick. Terra cotta is light, having adensity of 120 lb/ft3 (1,922 kg/m3), and withstands fire and frost.

TETRACHLOROETHANE. A colorless liquid of the chemical formulaCHCl2 CHCl2 employed as a solvent for organic compounds such asoils, resins, and tarry substances. It is an excellent solvent for sulfur,phosphorus, iodine, and various other elements. It is used as a paintremover and bleacher, as an insecticide, and in the production ofother chlorine compounds. It is also called acetylene tetrachlorideand is made by the combination of chlorine with acetylene.Tetrachloroethane boils at 291°F (144°C), freezes at 33°F (36°C),is nonflammable, and has a specific gravity of 1.601. It is narcotic andtoxic, and the breathing of the vapors is injurious. Mixed with dilutealkalies, it forms explosive compounds. In the presence of moisture itis very corrosive to metals. Mixed with zinc dust and sawdust, it isemployed as a smoke screen.

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THALLIUM. A soft, bluish-white metal, symbol Tl, resembling leadbut not as malleable. The specific gravity is 11.85, and melting point578°F (302°C). At about 600°F (316°C) it ignites and burns with agreen light. Electrical conductivity is low. It tarnishes in air, formingan oxide coating. It is attacked by nitric acid and by sulfuric acid. Themetal has a tensile strength of 1,300 lb/in2 (9 MPa) and a Brinellhardness of 2. Thallium-mercury alloy, with 8.5% thallium, is liq-uid with a lower freezing point than mercury alone, 76°F (60°C),and is used in low-temperature switches. Thallium-lead alloys arecorrosion-resistant and are used for plates on some chemical equip-ment parts.

The metal occurs in copper pyrites and zinc ores, and the chiefsource is the flue dust of smelters from sphalerite ores. Four rareminerals are ores of thallium: vrbaite, Tl2S 3(AsSb)2S3, is found inMacedonia; lorandite, Tl2S 2As2S3, is found in Macedonia andWyoming; hutchinsonite, PbS (TlAg)2S 2As2S3, occurs inSwitzerland and Sweden; and crooksite, (CuTlAg)2Se, is found inSweden. The salts of thallium are highly poisonous, the sulfide beingused as a rat poison. Thallium oxysulfide is used in light-sensitivecells. It is also sensitive to infrared rays and is used for dark signal-ing. Thallium sulfate, Tl2(SO4)3, is a crystalline powder used as aninsecticide. It is more toxic than lead compounds. Thallium also giveshigh refraction to optical glass. Thallium bromide iodide crystals,grown synthetically, are used for infrared spectrometers.

The so-called alkali-halide crytals used in the discriminatorcircuits of scintillators for gamma spectrometry contain thallium.They separate the slow-decaying pulses of protons produced as fastneutrons from the electron pulses produced by gamma absorption. AFrench crystal, called Scintibloc, is sodium iodide thallide,NaI(Tl). The cesium iodide thallide crystal, CsI(Tl), gives a veryblue light under electron excitation.

THERMOPLASTIC ELASTOMERS. A group of polymeric materials hav-ing some characteristics of both plastics and elastomers. Also calledelastoplastics and TPEs. Requiring no vulcanization or curing, theycan be processed on standard plastics processing equipment. They arelightweight, resilient materials that perform well over a wide temper-ature range. There are a half-dozen different types of elastoplastics.The olefinics, or TPOs, range in Shore A hardness from 55 to 90.Specialty flame-retardant and semiconductive grades are also avail-able. The TPOs are used in autos for paintable body filler panels andair deflectors, and as sound-deadening materials in diesel-poweredvehicles. The styrenics are block copolymers, composed of poly-styrene segments in a matrix of polybutadiene or polyisoprene.

954 THALLIUM




In recent years, metallocene catalysis has enhanced the perfor-mance and processability of olefinic and styrenic TPEs. For ethylenecopolymers and terpolymers, it may permit full or partial replace-ment of ethylene-propylene (EP) or ethylene-propylene-diene-monomer (EPDM) as the elastomer phase and increaselow-temperature impact strength, or toughness. Metallocene-cat-alyzed polyolefin plastomers are combined with styrenic copolymersin “supersoft” EX215 thermoplastic elastomer from GLS Corp. fortube and profile applications in sports and medical products. It has aShore A hardness of 15, previously available only in foam, and 400%elongation. An earlier, injection-moldable soft styrenic from GLS isDynaflex TPE G-6703. Clear TPEs and plastomers based on olefinicand styrenic monomers are used for sheet and breathable film inpackaging and nonpackaging products. Styroflex, from BSAF, is astyrene-butadiene block copolymer, with about 70% styrene, intendedfor food-packaging film. Film of Grade BX 6105 (84A), coextrudedwith ethylene vinyl acetate (for the outside surface) provides fullrecovery at 400% elongation, and 650% ultimate elongation.Styrolux, of BSAF, is a styrene-butadiene-styrene (SBS) triblockTPE. Versaflex alloys, from GLS, are based on Shell Chemicals’styrene-ethylene-butadiene-styrene (SEBS) Kraton G TPE. KratonD 1401P is an SBS type with, like Styroflex, about 70% polystyrene.Dow’s Index ethylene-styrene copolymer behaves similarly toStyroflex.

Thermoplastic urethanes, or TPUs, are of three types: poly-ester-urethane, polyether-urethane, and caproester-urethane.All three are linear polymeric materials and therefore do not have theheat resistance and compression set of the cross-linked urethanes.

Desmopan TPUs, from Bayer, are polyether-polyester copolymersapproaching the hydrolysis and microbial resistance of polyether ure-thanes while providing the mechanical properties and lower cost ofthe polyester kind. The softest grade (Shore A 75) is for injectionmolding and extrusion; the others (Shore A 80 to 90) are mainly forextrusion. Arnitel, of DSM Engineering Plastics, consists of alternat-ing hard segments of crystalline polybutylene terephthalate (PBT)and soft segments of amorphous polyester or polyether urethane.With 38 to 74 Shore D hardness, there are three principal grades: Etypes for the best flexible-fatigue life, color retention in aging, andtear strength; P types for the best short-term, low-temperature flexi-bility; and the U for the highest continuous-use temperature andabrasion resistance. Hytrel copolyester, from Du Pont, combinesPBT with Hytrel elastomer for breathable films for packaging. Alsofor such film products are Pebax, from Elf Atochem, which combinesNylon 12 and polyether urethane, and Dow’s Pellethane.

THERMOPLASTIC ELASTOMERS 955




Envirosoft, an aliphatic TPU developed by Textron and supplied byBayer, features excellent abrasion resistance and is used forunpainted auto instrument-panel covers.

There are several TPE vulcanizates (TPVs). Santoprene, fromAdvanced Elastomer Systems, combines EPDM and polypropylene.Suitable for injection molding, extrusion, blow molding, and thermo-forming, it is as heat resistant as EPDM and as fluid resistant as gen-eral-purpose chloroprene. Its performance is between that of theolefinic and urethane TPEs. Grades range from 35 A to 50 D Shorehardness, 0.94 to 0.97 specific gravity, 285 to 4,000 lb/in2 (2 to 28MPa) tensile strength, and compression set (168 h) 22 to 81%. Itexcels in dynamic fatigue resistance, has a continuous use tempera-ture of 275°F (135°C), and a brittle point (35 to 87 Shore hardnessgrades) of 76°F (60°C). Uses include auto rack-and-pinion boots,air ducts, cable covers, and window-body seals; appliance gaskets,hose connectors, and baffles; business machine printer rollers andvibration isolators; and electrical cables, connectors, cords, andpower-transmission components. Other company TPEs and their keyfeature are Geolast (oil resistance), Trefsin (low gas permeability),Dytron XL (electrical properties), Vyram (general purpose), andVistaFlex (surface quality). Pacrel, a TPV from Optatech (Finland),contains a continuous olefin phase and a dispersed cross-linked poly-acrylate. It features excellent resistance to oils and gasoline; excellentflex resistance, adhesion to polyolefins, and surface quality; and goodresistance to ozone and ultraviolet. Shore A hardness ranges from 70to 94, depending on grade, tensile strength from 870 to 1,450 lb/in2 (6to 10 MPa), and ultimate elongation from 180 to 560%. It can beblended with other polymers, including styrene-ethylene-butadiene-styrene (SEBS), providing 45 to 85 Shore A hardness and superior oilresistance. Hyperalloy Actymer, of Riken Vinyl Industry of Japan,is an alloy of TPU and styrene-ethylene-propylene-styrene vulcan-izate. It provides greater abrasion resistance than TPOs and betterheat resistance, flexibility, and processability than TPUs without less-ening their abrasion and oil resistance.

THORIUM. A soft, ductile, silvery-white metal, symbol Th, occurs innature to about the same extent as lead but so widely disseminated inminute quantities difficult to extract that it is considered a raremetal. It was once valued for use in incandescent gas mantles in theform of thorium nitrate, Th(NO3)4, but is now used chiefly fornuclear and electronic applications. Thorium powder is produced bycalcium reduction of thorium oxide. The impure powder burns in theair with great brilliance. Pure thorium metal in sheet form has a spe-cific gravity of 11.7, a melting point of 3090°F (1699°C), and a tensile

956 THORIUM




strength of about 35,000 lb/in2 (241 MPa). Even small amounts ofimpurities affect the physical properties greatly, and cold workingincreases the strength. The metal is dissolved by aqua regia or byhydrochloric acid.

Natural thorium consists largely of the alpha-emitting isotope tho-rium 232, and is a powerful emitter of alpha rays. Thorium producesfissile material, uraniuim 233, only when triggered by another fissionmaterial. Under neutron bombardment it forms protactinium whichis nonfissile but decays slowly into fissile uranium 233. But, in rapidburning, the buildup of protactinium may be converted to the nonfis-sile uranium 234.

Thorium 230 is found in minerals that contain uranium andradium and was originally considered as a separate metal under thename of ionium. It is radioactive, emitting alpha rays. It has a half-life of 76,000 years, slowly converting to radium. The original produc-tion was from the fractionation of uranium ores. It was used as anadditive in spark plug wire, but is too expensive for this purpose.

The chief thorium ore is the mineral monazite, occurring as sandor in granular masses, usually as sea sand. It is the chief source ofthorium oxide and of the rare-earth metals. Most of the monazitecomes from Brazil, India, and the East Indies. The monazite sands ofBrazil contain 8% thorium oxide, or thoria, ThO2. The ore of Indiamay have as high as 10%, but is marketed on the basis of 8% oxideand 60 rare-earth metals. Thoria has a high melting point, 5522°F(3050°C), but its use as a refractory ceramic is limited because of itshigh cost and radioactivity. Monazite contains about 0.008 lb (3.5 g) ofmesothorium per 1,000 tons (907 metric tons) and usually has 30 to35% of the oxides of lanthanum, yttrium, neodymium, andpraseodymium, and a small amount of europium. Mesothorium wasoriginally considered a separate element, but is an isotope of thorium,with an atomic weight of 228 and a half-life of 6.7 years. The radia-tions from mesothorium are the same as those from radium—alpha,beta, and gamma rays. As it decomposes, it forms radiothorium,which is identical in chemical properties to thorium but emits a pow-erful alpha radiation. It is used in luminous paints and is a safer acti-vator for this purpose than radium, but is scarcer and moreexpensive, and has a shorter life.

The type of monazite called uranothorite, from the Bancroft areaof Canada, contains from 0.04 to 0.27% thorium oxide. The thorium isrecovered from the waste liquors of the uranium treatment plant. Therare mineral thorite, found in Norway, is a thorium silicate,ThSiO2. It occurs in crystals or massive, orange to black in color, andhas a resinous luster and a specific gravity of about 5.

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Thoria-urania ceramics are used for reactor-fuel elements. Theyare reinforced with columbium or zirconium fibers to increase ther-mal conductivity and shock resistance. Thorium-tungsten alloyshave been used for very high-voltage electronic filaments. The incan-descent mantle, invented by Welsbach in 1893 and widely used dur-ing the period of gas lighting, consisted of a mixture of 98 to 99%thorium nitrate and 1 to 2 cerium oxide. The nitrate is converted tothorium oxide on ignition, with an increase of 10 times its originalvolume, and glows in the gas flame with an intense, white light.

THUYA. The wood of the tree Thuya plicata, also known as westernred cedar, giant arbor vitae, shinglewood, and Pacific redcedar. The tree grows in cool, humid coastal regions from Alaska tonorthern California, and the wood is widely used for shingles, poles,and tanks. It is lightweight, soft, and weak, with a straight, coarsegrain, but is durable. The sapwood is white and the heartwood red-dish. The tree grows to great size, reaching to 200 ft (61 m) in heightand 16 ft (5 m) in diameter at the age of 1,000 years. Northernwhite cedar is the wood of the tree T. occidentalis, of the northeast-ern United States. It is also called white cedar, arbor vitae,swamp cedar, or simply cedar. The wood is soft, knotty, brittle, andweak, but very durable. It is used for shingles, poles, posts, and lum-ber for small boats. The sapwood is white and the heartwood lightbrown. The trees have a diameter of 1 to 3 ft (0.3 to 0.9 m) and aheight of 25 to 75 ft (8 to 23 m). Thuya leaf oil, used as a fixative inperfumery, is a colorless oil with a bornyl acetate odor, distilled fromthe leaves.

TIN. A silvery-white, lustrous metal, symbol Sn, with a bluish tinge.It is soft and malleable and can be rolled into foil as thin as 0.0002 in(0.0051 cm). Tin melts at 450°F (232°C). Its specific gravity is 7.298,close to that of steel. Its tensile strength is 4,000 lb/in2 (28 MPa). Itshardness is slightly greater than that of lead, and its electrical con-ductivity is about one-seventh that of silver. It is resistant to atmo-spheric corrosion, but is dissolved in mineral acids. The cast metalhas a crystalline structure, and the surface shows dendritic crystalswhen cast in a steel mold. Tin pest is the breaking up of the metalinto a gray powder which occurs below 66°F (19°C), and the metal isnot used for applications at very low temperatures.

Tin is used in brasses, bronzes, and babbitts, and in soft solders.Tin with 0.4% copper is used as foil and for collapsible tubes. One ofthe most important uses is for the making of tinplate, an electroplat-ing material. Electroplated tin has a fine, white color, gives adurable protective finish, and also has a lubricating effect as a bear-

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ing surface. Standard tin of the London Metal Exchange must con-tain over 99.75% tin. The common grade is known as Grade A tin.Straits tin is 99.895% pure. Federal specifications for pig tin are99.80% minimum. Block tin is virgin tin cast in stone molds. Evensmall traces of impurities have an influence on the physical proper-ties of tin. Lead softens the metal; arsenic and zinc harden it. Anaddition of 0.3% nickel doubles the tensile strength; 2 copperincreases the strength 150%. Pure tin melts sharply, but smallamounts of impurities broaden the melting point. Tin powder, usedfor making sintered alloys, is 99.8% pure, in powder from 100 to 300mesh. The tin crystals used in the chemical industry are tin chlo-ride, or stannous chloride, SnCl2 2H2O, coming as large, colorlesscrystals or white, water-soluble flakes, melting at 475°F (246°C).They are also used for immersion tinning of metals and for sensitiz-ing glass and plastics before metallizing. The chief source of tin is themineral cassiterite, but Nigerian columbite may contain up to 6% tinoxide. The principal tin-producing countries are Indonesia, Malaya,Bolivia, China, and Nigeria; but tin mines have been worked inCornwall since ancient times, and tin is also found in Canada and inirregular quantities in some other areas.

Tin oxide, or stannous oxide, is a fine, black, crystalline powderof composition SnO, made by oxidizing tin powder. It is used as anopacifier in ceramic enamels, as a ceramic color, as an abrasive, andas a coating for conductive glass. As a color in ceramics it is light-stable and acid-resistant. With magnesium and cobalt oxides itgives a sky-blue color called cerulean blue. It is also used with cop-per oxide to produce ruby glass.

Stannic oxide, SnO2, is a white powder used in ceramic glazes asan opacifier and for color. As little as 1 to 2% gives fluidity and highluster to glass. With chromates and lime, it gives pinks and maroonsin enamels, and with vanadium compounds it gives yellows. With goldchloride it gives brilliant-red jewelry enamels. Protectatin is thename of the Tin Research Institute for a thin, invisible film of oxideon tinplate to protect against sulfur staining and to give a base forpaint. It is produced by dipping the tinplate in a solution of trisodiumphosphate, sodium dichromate, and sodium hydroxide. Potassiumstannate, K2SnO3 3H2O, or sodium stannate, Na2SnO3 3H2O,may be used for immersion tinning of aluminum. Both come as white,water-soluble crystals. The term organotin usually refers to butylcompounds of the metal used as catalysts, or heat and light stabiliz-ers in vinyl polymers.

Stan-Guard 100, of Pfizer Inc., is a liquid butyl-tin compoundcontaining sulfur and used as a stabilizer in rigid PVC sheet. Abutyl-tin maleate powder is effective as a light stabilizer. Hollicide

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LT-125 is a water-soluble organo-trialkyl-tin used as a bacteriocidein paper and textile processing. It can be used over a wide pH range.

TINPLATE. Soft-steel plate containing a thin coating of pure tin onboth sides. A large proportion of the tinplate used goes into the manu-facture of food containers because of its resistance to the action ofvegetable acids and its nonpoisonous character. It solders easily, andalso is easier to work in dies than terneplate, so that it is preferredover terneplate for making toys and other cheap articles in spite of ahigher cost. Commercial tinplate comes in boxes of 112 sheets, 14 by20 in (0.36 by 0.51 m), and is designated by the net weight per boxwhen below 100 lb (45 kg). Heavy tinplate above 100 lb (45 kg) goesby number, as steel does, or by letter symbols. The weight of tin maybe as high as 1.7% of the total weight of the sheet. Coke plates carryas little tin as is necessary to protect and brighten the plate for tem-porary use. The tin of the coat forms compounds of FeSn2, Fe2Sn, andFeSn with the iron of the plate, and on a coke plate this compound is0.00006 to 0.00015 in (0.00015 to 0.00038 cm) thick. Best cokes carrymore tin than do the standard cokes. Charcoal plates have heaviercoats of tin designated by the letter A. The AAAAAA, or 6A, has theheaviest coating. Tinplate is made by the hot-dip process using palmoil as a flux, or by a continuous electroplating process. A base box con-tains 31,360 in2 (20 m2) of tinplate, and standard-dip tinplate has 1.5lb (0.7 kg) of tin per base box, while electrolytic plate has only 0.25 lb(0.1 kg) of tin per base box and much electrolytic tinplate for con-tainer use has only 0.10 lb (0.05 kg) of tin per base box.Electrotinning gives intimately adherent coatings of any desiredthickness, and the plate may have a serviceable coat as thin as0.00003 in (0.00008 cm), or about one-third that of the thinnest possi-ble dipped plate. A slight cold rolling of electrolytic tinplate gives abright, smooth finish.

Taggers was originally a name for tinplate that is undersized, orbelow the gage of the plate in the package, but the name taggers tinis also applied to light-gage plate. These sizes are No. 38 gage, 55 lb(25 kg); No. 37, 60 lb (27 kg); and No. 36, 65 lb (29 kg). Ductilite, ofWheeling-Pittsburgh Steel Corp., is a tinplate that is not made by hotrolling in packs, but is cold-rolled from single hot-rolled strip steel. Itis of uniform gage and does not have the thin edges of pack-rolledplate. It also has a uniform grain structure. Weirite, of Weirton SteelCorp., is cold-reduced coke tinplate. Black plate, used for cans inplace of tinplate where the tin protection is not necessary, is notblack, but is any sheet steel other than tinplate or terneplate in tin-plate sizes. It may be chemically treated to resist rust or corrosion.

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Electroplated tin-zinc coatings, developed at the InternationalTin Research Institute (ITRI) in England in the late 1940s, are morecorrosion-protective of steel than zinc alone. However, bath control isdifficult, and the sodium stannate and cyanide systems of the originalbath are toxic. In the early 1990s, ITRI developed the Stanzecprocess, which is cyanide-free, nontoxic, and more controllable. Theelectrolyte, or bath, is a mixture of sodium or potassium stannate,sodium or potassium zincate, sodium or potassium hydroxide, pluscomplexing and stabilizing agents, brighteners, and grain refiners.Any alloy composition can be deposited by barrel, brush, or rack plat-ing, and deposits of 70 to 80% tin with the balance zinc combine sol-derability with good corrosion resistance. A 75Sn–25Zn plate has aVickers hardness of 37, and the coatings are typically ductile andsuitable for painting. They also can be plated to brasses and high-copper alloys and are considered alternatives to plating withtoxic cadmium in many applications.

TITANATES. Compounds made by heating a mixture of an oxide orcarbonate of a metal and titanium dioxide. High dielectric constants,high refractive indices, and ferroelectric properties contribute primar-ily to their commercial importance. Barium titanate crystals,BaTiO3, are made by die-pressing titanium dioxide and barium car-bonate and sintering at high temperature. This crystal belongs to theclass of perovskite in which the closely packed lattice of barium andoxygen ions has a barium ion in each corner and an oxygen ion in thecenter of each face of a cube with the titanium ion in the center of theoxygen octahedron. Because of their high dielectric constant and com-patibility with high-temperature superconductors, thin perovskiteoxide films are candidates for tunable microwave devices. For piezo-electric use the crystals are subjected to a high current, and they givea quick response to changes in pressure or electric current. They alsostore electric charges and are used for capacitors. Glennite 103, ofGulton Industries Inc., is a piezoelectric ceramic molded from bar-ium titanate modified with temperature stabilizers. Bismuth stan-nate, Bi2(SnO3) 5H2O, a crystalline powder that dehydrates at about284°F (140°C), may be used with barium titanate in capacitors toincrease stability at high temperatures. Ceramelex is molded poly-crystalline barium titanate. Lead zirconate–lead titanate is apiezoelectric ceramic that can be used at higher temperatures thanbarium titanate. Lead titanate, PbTiO3, is used as a less costly sub-stitute for titanium oxide. It is yellowish and has only 60% of the hid-ing power, but is very durable and protects steel from rust. Butyltitanate is a yellow, viscous liquid used in anticorrosion varnishes

TITANATES 961




and for flameproofing fabrics. It is a condensation product of thetetrabutyl ester of ortho-titanic acid, and contains about 36% tita-nium dioxide. Calcium titanate, CaTiO3, occurs in nature as themineral perovskite. As a ceramic, it has a room-temperature dielectricconstant of about 160. It is frequently used as an addition to bariumtitanate or by itself as a temperature-compensating capacitor.Magnesium titanate, MgTiO3, crystallizes as an ilmenite ratherthan a perovskite structure. It is not ferroelectric, and is used withtitanium dioxide to form temperature-compensating capacitors. It hasalso been used as an addition agent to barium titanate. Strontiumtitanate, SrTiO3, has a cubic perovskite structure at room tempera-ture. It has a dielectric constant of about 230 as a ceramic, and it iscommonly used as an additive to barium titanate to decrease theCurie temperature. By itself, it is used as temperature-compensatingmaterial because of its negative temperature characteristics.Strontium titanate, used as a brilliant diamondlike gemstone, is astrontium mesotrititanate. Stones are made up to 4 carats. Therefractive index is 2.412. It has a cubic crystal similar to the diamond,but the crystal is opaque in the X-ray spectrum. Crystalline silico-titanate, developed at Texas A&M University and Sandia NationalLaboratories, has potential use in the cleanup of radioactive wastes.As an inorganic ion-exchange agent, it promotes exchange of residentsodium ions for ions of radioactive elements. It has proved effective inremoving cesium from neutral and highly acidic waste solutions.Titanate fibers can be used as reinforcement in thermoplastic mold-ings. The fibers, called Fybex, produced by LNP EngineeringPlastics, Inc., can also be used in plated plastics to reduce thermalexpansion, warpage, and shrinkage. Titanate fibers in plastics alsoprovide opacity.

TITANIUM AND TITANIUM ALLOYS. A metallic element, symbol Ti,occurring in a great variety of minerals. It was first discovered as anelement in 1791 in a black magnetic sand at Manachin, Cornwall,England, and called menachite, from the name of the sand, mena-chinite. Its chief commercial ores are rutile and ilmenite. In rutile itoccurs as an oxide. It is an abundant element but is difficult to reducefrom the oxide. High-purity titanium (99.9%) has a melting point ofabout 3034°F (1668°C), a density of 0.163 lb/in3 (4,512 kg/m3), andtensile properties at room temperature of about 34,000 lb/in2 (234MPa) ultimate strength, 20,000 lb/in2 (138 MPa) yield strength, and54% elongation. It is paramagnetic and has low electrical conductivityand thermal expansion.

The commercial metal is produced from sponge titanium, which ismade by converting the oxide to titanium tetrachloride followed by

962 TITANIUM AND TITANIUM ALLOYS




reduction with molten magnesium. The metal can also be produced indendritic crystals of 99.6% purity by electrolytic deposition from tita-nium carbide. Despite its high melting point, titanium reacts readilyin copper and in other metals and is much used for alloying and fordeoxidizing. It is a more powerful deoxidizer of steel than silicon ormanganese. An early German deoxidizing alloy known as Badinmetal contained about 9% aluminum, 19 silicon, 5 titanium, and thebalance iron. Titanium copper, used for deoxidizing nonferrous met-als, is made by adding titanium to molten copper. The congealed alloyis broken into lumps.

One of the chief uses of the metal has been in the form of titaniumoxide as a white pigment. It is also valued as titanium carbide forhard facings and for cutting tools. Small percentages of titanium areadded to steels and alloys to increase hardness and strength by theformation of carbides or oxides or, when nickel is present, by the for-mation of nickel titanide. The first titanium alloys in the UnitedStates were produced in 1945 by the Bureau of Mines.

Titanium is one of the few allotropic metals (steel is another); thatis, it can exist in two different crystallographic forms. At room tem-perature, it has a close-packed hexagonal structure, designated as thealpha phase. At around 1625°F (884°C), the alpha phase transformsto a body-centered cubic structure, known as the beta phase, which isstable up to titanium’s melting point of about 3050°F (1677°C).Alloying elements promote formation of one or the other of the twophases. Aluminum, for example, stabilizes the alpha phase; that is, itraises the alpha to the beta transformation temperature. Other alphastabilizers are carbon, oxygen, and nitrogen. Beta stabilizers, such ascopper, chromium, iron, molybdenum, and vanadium, lower the trans-formation temperature, therefore allowing the beta phase to remainstable at lower temperatures, and even at room temperature.Titanium’s mechanical properties are closely related to theseallotropic phases. For example, the beta phase is much stronger, butmore brittle, than the alpha phase. Titanium alloys therefore can beusefully classified into three groups on the basis of allotropic phases:alpha, beta, and alpha-beta alloys.

Titanium and its alloys have attractive engineering properties.They are about 40% lighter than steel and their moderate weight andhigh strengths, up to 200,000 lb/in2 (1,379 MPa), gives titanium alloysthe highest strength-to-weight ratios of any structural metal.Furthermore, this exceptional strength-to-weight ratio is maintainedfrom 420°F (216°C) up to 1000°F (538°C). A second outstandingproperty of titanium materials is their corrosion resistance. The pres-ence of a thin, tough, oxide surface film provides excellent resistanceto atmospheric and sea environments as well as a wide range of

TITANIUM AND TITANIUM ALLOYS 963




chemicals, including chlorine and organics containing chlorides.Being near the cathodic end of the galvanic series, titanium performsthe function of a noble metal. Titanium and its alloys, however, canreact pyrophorically in certain media. Explosive reactions can occurwith fuming nitric acid containing less than 2% water or more than 6nitrogen dioxide and, on impact, with liquid oxygen. Pyrophoric reac-tions also can occur in anhydrous liquid or gaseous chlorine, liquidbromine, hot gaseous fluorine, and oxygen-enriched atmospheres.

Fabrication is relatively difficult because of titanium’s susceptibil-ity to hydrogen, oxygen, and nitrogen impurities, which cause embrit-tlement. Therefore elevated-temperature processing, includingwelding, must be performed under special conditions that avoid diffu-sion of gases into the metal. Heat is usually required in most formingoperations.

Commercially pure titanium and many of the titanium alloys arenow available in most common wrought mill forms, such as plate,sheet, tubing, wire, extrusions, and forgings. Castings can also beproduced in titanium and some of the alloys, investment casting andgraphite-mold (rammed graphite) casting being the principal meth-ods. Because of titanium’s highly reactive nature in the presence ofsuch gases as oxygen, the casting must be done in a vacuum furnace.Because of their high strength-to-weight ratio primarily, titanium andtitanium alloys are widely used for aircraft structures requiringgreater heat resistance than aluminum alloys. Because of their excep-tional corrosion resistance, however, they (unalloyed titanium pri-marily) are also used for chemical processing, desalination, and powergeneration equipment; marine hardware; valve and pump parts; andprosthetic devices.

There are several grades of commercially pure titanium, alsocalled unalloyed titanium. They are distinguished by their impu-rity content, that is, the maximum amount of carbon, nitrogen, hydro-gen, iron, and oxygen permitted. Regardless of grade, carbon andhydrogen contents are 0.10 and 0.015% maximum, respectively.Maximum nitrogen is 0.03%, except for 0.05 in Grades 3 and 4. Ironcontent ranges from as much as 0.20% in Grade 1, the most pure(99.5) grade, to as much as 0.05 in Grade 4, the least pure (98.9).Maximum oxygen ranges from 0.18% in Grade 1 to 0.40 in Grade 4.Grade 7, 99.1% pure based on maximum impurity content, is actuallya series of alloys containing 0.12 to 0.25% palladium for improved cor-rosion resistance in hydrochloric, phosphoric, and sulfuric acid solu-tions. Palladium content has little effect on tensile properties, butimpurity content, especially oxygen and iron, has an appreciableeffect. Minimum tensile yield strengths range from 25,000 lb/in2 (172





MPa) for Grade 1 to 70,000 lb/in2 (483 MPa) for Grade 4. Grade 16,from Oremet–Wah Chang, has only 0.05% palladium and, thus is lesscostly than Grade 7 alloys. Titanium-ruthenium alloy Ti-0.2Ru,developed by the research group Mintek of South Africa, is said tomatch the corrosion resistance of Grade 7 alloys at lower cost. Its ulti-mate tensile strength is 84,000 lb/in2 (579 MPa) and the elongation isabout 23%, both greater than those of Grade 7.

There are three principal types of titanium alloys: alpha or near-alpha alloys, alpha-beta alloys, and beta alloys. All are avail-able in wrought form and some of each type for castings as well. Inrecent years, some also have become available in powder composi-tions for processing by hot isostatic pressing and other powder-met-allurgy techniques. Titanium alpha alloys typically containaluminum and usually tin. Other alloying elements may include zir-conium, molybdenum, and, less commonly, nitrogen, vanadium,columbium, tantalum, or silicon. Though they are generally not capa-ble of being strengthened by heat treatment (some will respondslightly), they are more creep-resistant at elevated temperature thanthe other two types, are preferred for cryogenic applications, and aremore weldable but less forgeable. Ti-5Al-2Sn, which is available inregular and ELI grades (extra-low interstitial) in wrought and castforms, is the most widely used. In wrought and cast form, minimumtensile yield strengths range from 90,000 lb/in2 (621 MPa) to 115,000lb/in2 (793 MPa) and tensile modulus is on the order of 15.5 106 to16 106 lb/in2 (106,873 to 110,320 MPa). It has useful strength toabout 900°F (482°C) and is used for aircraft parts and chemical pro-cessing equipment. The ELI grade is noted for its superior toughnessand is preferred for containment of liquid gases at cryogenic temper-atures. Other alpha or near-alpha alloys and their performance bene-fits include Ti-8Al-1Mo-1V (high creep strength to 900°F),Ti-6Al-2Sn-4Zr-2Mo [creep resistance and stress stability to 1100°F(593°C)], Ti-6Al-2Cb-1Ta-0.8Mo (toughness, strength, weldability),and Ti-2.25Al-11Sn-5Zr-1Mo [high tensile strength—135,000 lb/in2

(931 MPa) yield, superior resistance to stress corrosion in hot saltmedia at 900°F]. Another alpha alloy, Ti-0.3Mo-0.8Ni, also known asTiCode 12, is noted for its greater strength than commercially puregrades and equivalent or superior corrosion resistance, especially tocrevice corrosion in hot salt solutions. The near alpha alloy Ti-5Al-1Sn-1Zr-1V-0.8Mo combines good toughness and weldability, corrosionand stress-corrosion resistance, and room-temperature creep resistance.Developed by Titanium Metals Corp., it has longitudinal tensile yieldstrength of 103,000 to 116,000 lb/in2 (710 to 800 MPa), depending onsheet and plate thickness, and elongation of 10 to 15%. Machinability





and forgeability are quite similar to those of the alpha-beta Ti-6Al-4Valloy. The alloy is said to be ideal for marine fasteners.

Titanium alpha-beta alloys, which can be strengthened by solu-tion heat treatment and aging, afford the opportunity of parts fabrica-tion in the more ductile annealed condition and then can beheat-treated for maximum strength. Ti-6Al-4V, which is available inregular and ELI grades, is the principal alloy, its production alonehaving accounted for about half of all titanium and titanium-alloyproduction. In the annealed condition, tensile yield strength is about130,000 lb/in2 (896 MPa) and 13% elongation. Solution treating andaging increase yield strength to about 150,000 lb/in2 (1,034 MPa).Yield strength decreases steadily with increasing temperature, toabout 70,000 lb/in2 (483 MPa) at about 950°F (510°C) for the agedalloy. At 850°F (454°C), aged bar has a 1,000-h stress-rupturestrength of about 50,000 lb/in2 (345 MPa). Uses range from aircraftand aircraft turbine parts to chemical processing equipment, marinehardware, and prosthetic devices. The alloy is also the principal alloyused for superplastically formed, and superplastically formed andsimultaneously diffusion-bonded, parts. At 1650 to 1700°F (899 to927°C) and low strain rates, the alloy exhibits tensile elongations of600 to 1,000%, a temperature range also amenable to diffusion-bond-ing the alloy. SP700, from Japan’s NKK Corp., exhibits some 2,000%elongation at about 1420°F (770°C).

Although Ti-6Al-4V and Ti-6Al-4V ELI have served for armorplate—the latter being superior—less expensive titanium armoralloys have been introduced by Oremet–Wah Chang. They contain2.5 to 5.4% aluminum, 2.0 to 3.4 vanadium, 0.2 to 2 iron, and 0.2 to0.3 oxygen.

Following are other alpha-beta alloys and their noteworthy charac-teristics. Ti-6Al-6V-2Sn: high strength to about 600°F (315°C) butlow toughness and fatigue resistance. Ti-8Mn: limited use for flatmill products, not weldable. Ti-7Al-4Mo: a forging alloy mainly, butlimited use; and a 150,000 lb/in2 (1,034 MPa) yield strength in theaged condition. Ti-6Al-2Sn-4Zr-6Mo: high strength, 170,000 lb/in2

(1,172 MPa) yield strength, decreasing to about 110,000 lb/in2 (758MPa) at 800°F (427°C); for structural applications at 750 to 1000°F(400 to 540°C). Ti-5Al-2Sn-2Zr-4Mo-4Cr and Ti-6Al-2Sn-2Zr-2Mo-2Cr: superior hardenability for thick-section forgings; high modu-lus—about 17 106 to 18 106 lb/in2 (117,215 to 124,110 MPa),respectively; tensile yield strength of about 165,000 lb/in2 (1,138MPa). Ti-6Al-2Sn-2Zr-2Mo-2Cr castings of the same nominal composi-tion as the wrought alloy except for a reduction of silicon to 0.1% byweight also exhibit good mechanical performance after hot isostatic





pressing. Tensile properties for several duplex and triplex heat treat-ments, and thicknesses of 0.5 to 1.5 in (12.5 to 37.5 mm), demonstrateultimate strengths of 142,000 to 154,000 lb/in2 (979 to 1,062 MPa),yield strengths of 127,000 to 135,000 lb/in2 (876 to 931 MPa), elonga-tions of 6.7 to 11.9%, and average fracture toughness of 97,800 to125,000 lb/in2 . in0.5 (108 to 140 MPa.m0.5). Ti-10V-2Fe-3Al: best ofthe alloys in toughness at a yield strength of 130,000 lb/in2 (896MPa); can also be aged to a yield strength of about 172,000 lb/in2

(1,186 MPa); intended for use at temperatures to about 600°F(315°C). Ti-3Al-2.5V: a tubing and fastener alloy primarily, moderatestrength and ductility, weldable.

Beta titanium alloys, fewest in number, are noted for their hard-enability, good cold formability in the solution-treated condition, andhigh strength after aging. On the other hand, they are heavier thantitanium and the other alloy types, their density ranging from about0.174 to 0.175 lb/in3 (4.84 g/cm3) for Ti-13V-11Cr-3Al, Ti-8Mo-8V-2Fe-3Al, and Ti-3Al-8V-6Cr-4Zr-4Mo to 0.183 lb/in3 (5,065 kg/m3) for Ti-11.5Mo-6Zr-4.5Sn, which is also known as Beta III. They are also theleast creep-resistant of the alloys. Ti-13V-11Cr-3Al, a weldable alloy,can be aged to tensile yield strengths as high as 195,000 lb/in2 (1,345MPa) and retains considerable strength at temperatures to 600°F, buthas limited stability at prolonged exposure to higher temperatures.

Timetal 21S, of Titanium Metals Corp., is a metastable beta alloyof composition Ti-15Mo-3Al-2.7Cb-0.3Fe-0.2Si-0.13O with maxi-mum amounts of 0.05% carbon, 0.05 nitrogen, 0.015 hydrogen, and0.4 residual elements. It is unique among titanium and titaniumalloys in its resistance to Skydrol, a widely used aircraft hydraulicfluid. Also, its oxidation resistance at 1200°F (649°C) is far superior tothat of commercially pure titanium. Aging at 1000°F (538°C) resultsin tensile yield strengths of 179,000 to 187,000 lb/in2 (1,234 to 1,289MPa). The alloy can be rolled to thin foil, a form useful for metal-matrix composites. Timetal 15-3, of the nominal composition Ti-15V-3Al-3Cr-3Sn, is another metastable beta alloy. It is a high-strength,cold-formed strip alloy with ultimate tensile strength of 145,000 to180,000 lb/in2 (1,000 to 1,241 MPa), tensile yield strengths of 140,000to 170,000 lb/in2 (965 to 1,172 MPa) and elongations of 5 to 7%,depending on aging temperature and time after solution heat-treat-ment and air cooling.

Timetal LCB (low-cost beta), a Ti-6.8Mo-4.5Fe-1.5Al alloy of thesame company, reduces formulating cost because iron need not beremoved from the ore. It is a candidate for replacing steel spring wireand requires processing temperatures of only 300 to 400°F (149 to204°C). The alloy has a tensile strength of 150,000 lb/in2 (1,034 MPa)





and a tensile modulus of 16.5 106 lb/in2 (113,768 MPa).Oremet–Wah Chang’s Tiadyne 3515, also known as Titanium AlloyC and Ti-1270, contains 50% titanium, 35 vanadium, and 15chromium. It is noted for high-temperature strength and the abilityto resist combustion in air at temperatures and pressures far greaterthan for Ti-6Al-4V alloy. The average tensile yield strength is 137,000lb/in2 (945 MPa), 98,000 lb/in2 (676 MPa) at 1000°F (538°C). It isavailable in rod, various flat products, and powder, and is alsocastable. Tiadyne 3510 contains about 35% zirconium, 10.5columbium, and 0.07 to 0.13 oxygen. Though rather heavy (density is0.19 lb/in3, 5,300 kg/m3) and having a low modulus (10.4 106 lb/in2,71,700 MPa), tensile yield strength is 160,000 lb/in2 (1,103 MPa),weldability is good and the alloy can be surface hardened by oxidationfor high wear resistance. It is also superplastic at certain elevatedtemperatures and is at least as corrosion resistant as commerciallypure titanium. Prosthetic devices, firearm firing mechanisms, andsprings are potential uses. Ti-45Cb, of this company, features supe-rior resistance to oxidizing environments and combustion in pureoxygen. The alloy has a density of 0.206 lb/in3 (5,702 kg/m3), an ulti-mate tensile strength of 80,000 lb/in2 (552 MPa), a tensile yieldstrength of 70,000 lb/in2 (483 MPa)—29,000 lb/in2 (200 MPa) at752°F (400°C)—23% elongation, and a modulus of elasticity of 9 106 lb/in2 (62,055 MPa). Its corrosion resistance may be slightly bet-ter than that of titanium in sulfuric acid and in hydrochloric acid atconcentrations of less than 20%. Ti-45Cb has been used for auto-clave vent lines in processing gold ores, for parts of oxygen injectorsexposed to pure oxygen, and, for hot wet-oxidation equipment usedin wastewater processing. Applications include aerospace rivets,high-pressure oxygenated gas vents, oxygen lances for pressure oxi-dation reactors, valves for corrosive oxygenated processes, andsuperconducting wire.

In an effort to spur nonaerospace uses, manufacturers have intro-duced several low-cost titanium alloys which are roughly similar instrength to aerospace alloy Ti-6Al-4V but which may sacrifice certainperformance features required in aerospace applications. These alloysinclude titanium alloy Auto-grade, of Allvac, titanium alloys RMand VM of RMI Titanium Co., and Timetal-62S of Titanium MetalsCorp. To reduce cost, Auto-grade is initially forged and rolled in thebeta region, then rolled in the alpha-beta range. RM, made of recycledmaterial, has a nominal Ti-6Al-4V composition. VM, for virgin metal,is Ti-6.4Al-1.2Fe, the iron substituting for more-costly vanadium.Timetal-62S, Ti-6Al-1.7Fe-0.1Si, also uses iron instead of vanadiumand costs about 25% less than the aerospace alloy.





Titanium alloys are leading candidates for metal-matrix compos-ites, primarily for aircraft and aircraft engine applications. Siliconcarbide fiber is a leading reinforcement. One approach, developed byHowmet Corp. and General Electric Aircraft Engines, is called bicast-ing. Preforms of alloys reinforced with the fiber are cast within amatrix alloy.

TITANIUM CARBIDE. A hard, crystalline powder of composition TiCmade by reacting titanium dioxide and carbon black at temperaturesabove 3272°F (1800°C). It is compacted with cobalt or nickel for use incutting tools and for heat-resistant parts. It is lighter in weight andless costly than tungsten carbide, but in cutting tools it is more brit-tle. When combined with tungsten carbide in sintered carbide toolmaterials, however, it reduces the tendency to cratering in the tool. Ageneral-purpose cutting tool of this type contains about 82% tungstencarbide, 8 titanium carbide, and 10 cobalt binder. Kentanium, ofKennametal, Inc., is titanium carbide in various grades with up to40% either cobalt or nickel as the binder, used for high-temperature,erosion-resistant parts. For highest oxidation resistance, only about5% cobalt binder is used. Kentanium 138, with 20% cobalt, is usedfor parts where higher strength and shock resistance are needed, andwhere temperatures are below about 1800°F (982°C). This materialhas a tensile strength of 45,000 lb/in2 (310 MPa), compressivestrength of 550,000 lb/in2 (3,792 MPa), and Rockwell A hardness 90.Kentanium 151A, for resistance to molten glass or aluminum, has abinder of 20% nickel. Titanium-carbide alloy, of Ford Motor Co., fortool bits, has 80% titanium carbide dispersed in a binder of 10 nickeland 10 molybdenum. The material has a Rockwell A hardness of 93and a dense, fine-grained structure. Ferro-Tic, of Chromalloy Corp.,has titanium carbide bonded with stainless steel. It has a Rockwell Chardness of 55. Machinable carbide is titanium carbide in a matrixof Ferro-Tic C tool steel. Titanium carbide tubing is produced inround or rectangular form 0.10 to 3 in (0.25 to 7.6 cm) in diameter, byTEEG Research, Inc. It is made by vapor deposition of the carbidewithout a binder. The tubing has a Knoop hardness above 2,000 and amelting point of 5880°F (3249°C). Grown single crystals of titaniumcarbide of Linde Co. have composition TiC0.94, with 19% carbon. Themelting point is 5882°F (3250°C), specific gravity 4.93, and Vickershardness 3,230.

TITANIUM ORES. The most common titanium ores are ilmenite andrutile. Ilmenite is an iron-black mineral having a specific gravity ofabout 4.5 and containing about 52% titanic oxide, or titania, TiO2.

TITANIUM ORES 969




The ore of India is sold on the basis of titanium dioxide content, andthe high-grade ore averages about 60% TiO2, 22.5 iron, and 0.4 silica.Ilmenite is a ferrotitanate, FeO TiO2, but much of the materialcalled ilmenite is arizonite, Fe2O3 3TiO2. Titanium ores are widelydistributed and plentiful. Ilmenite is found in northern New York,Florida, North Carolina, and in Arkansas, but the most extensive,accessible resources are found in Canada. The Quebec ilmenite con-tains 30% iron. The concentrated ore has about 36% TiO2, and 41iron, and is smelted to produce pig iron and a slag containing 70 TiO2which is used to produce titanium oxide. The beach sands of Senegalare mixed ores, the ilmenite containing 55 to 58% TiO2, and the zir-coniferous quartz containing 70 to 90 zirconia. The beach sands ofBrazil are washed to yield a product averaging 71.6% ilmenite, 13 zir-con, and 6 monazite. The Indian ilmenite also comes from beachsands. The ore of New York State averages 19% TiO2.

Rutile is a titanium dioxide, TiO2, containing theoretically 60%titanium. Its usual occurrence is crystalline or compact massive, witha specific gravity of 4.18 and 4.25 and Mohs hardness 6 to 6.5. Thecolor is red to brown, occasionally black. Rutile is found in granite,gneiss, limestone, or dolomite. It is obtained from beach sand ofnorthern Florida and Espirito Santo, Brazil, and is also produced inVirginia, and in Australia and India. Rutile and brookite andOctahedrite, or anatase, are produced in Arkansas andMassachusetts. The best Virginia concentrates are 92.5 to 98% TiO2,but some are 42% from rock originally showing 18.5 TiO2 in a body offeldspar. Rutile is marketed in the form of concentrates on the basisof 79 to 98.5% titanium oxide. It is used as an opacifier in ceramicglazes and to produce tan-colored glass. It is also employed for weld-ing-rod coatings. On welding rods it aids stabilization of the arc andfrees the metal of slag. Tanarc, used on welding rods as a replace-ment for rutile, is made from slag from Canadian titaniferoushematite, and it contains 70% TiO2.

TITANIUM OXIDE. The white titanium dioxide, or titania, of compo-sition TiO2, is an important paint pigment. The best quality is pro-duced from ilmenite, and is higher in price than many whitepigments but has great hiding power and durability. Off-color pig-ments, with a light buff tone, are made by grinding rutile ore. Thepigments have fine physical qualities and may be used wherever thecolor is not important. In the mid-1980s, TiO2 production moved fromthe sulfate process to the chloride process for environmental concernsand better performance. The rutile feedstocks of the latter process areless photocatalytically active than the former anatose feedstocks; they

970 TITANIUM OXIDE




have a slightly higher refractive index, thus better ability to scatterlight; and they accept more readily and bond more strongly to variouscoatings used to aid dispersion in processing. Titania is also substi-tuted for zinc oxide and lithopone in the manufacture of white rub-ber goods, and for paper filler. The specific gravity is about 4. Mixedwith blanc fixe, it is also marketed under the name of Titanox.Zopaque is a pure titanium oxide for rubber compounding. Ti-Pureof Du Pont is commercially pure titanium dioxide for pigment use.Duolith, of this company, is titanated lithopone pigment containing15% titanium dioxide, 25 zinc sulfide, and 60 barium sulfate.Titanium dioxide is also widely used as a photocatalyst. In anatoseform, it is the most commonly used catalyst in solar photocatalyticdetoxifications for, say, destroying bacteria. A titanium dioxide photo-catalytic film, developed by Toto Ltd. of Japan, has silver and coppercompounds immobilized on the surface to kill bacteria when exposedto fluorescent light. It is used to coat ceramic tiles in hospitals, foodand chemical processing plants, and other sanitary applications.

Titania crystals are produced in the form of pale-yellow, single-crystal boules for making optical prisms and lenses for applicationswhere the high refractive index is needed. The crystals are also usedas electric semiconductors, and for gemstones. They have a higherrefractive index than the diamond, and the cut stones are more bril-liant but are much softer. Knoop hardness is about 925, and the melt-ing point is 3317°F (1825°C). The refractive index of the rutile form is2.7, and that of the anatase is 2.5, while the synthetic crystals have arefractive index of 2.616 vertically and 2.903 horizontally. TionaRCL-188, from SCM Chemicals, is 50 to 80% titanium dioxide in apolyethylene carrier. It is intended to improve the melt flow rate ofvarious plastics.

Titanium oxide is a good refractory and electrical insulator. Thefinely ground material gives good plasticity without binders and ismolded to make resistors for electronic use. Micro sheet is titaniumoxide in sheets as thin as 0.003 in (0.008 cm) for use as a substitutefor mica for electrical insulation where brittleness is not important.Titania-magnesia ceramics were made in Germany in the form ofextruded rods and plates and pressed parts.

TOBACCO. The leaf of an unbranched annual plant of the genusNicotiana, of which there are about 50 species and many varieties. Itis used for smoking, chewing, snuff, insecticides, and production ofthe alkaloid nicotine. Commercial crops are grown in about 60 coun-tries, but about one-third of world production is in the United States.Only two species are grown commercially, N. tabacum, a tropical

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plant native to the West Indies and South America, and N. rustica,grown by the Indians of Mexico and North America before 1492.About 85% of world production is now from N. tabacum, and there aremore than 100 varieties of this plant.

Tobacco was not known in Europe until it was brought from theWest Indies by Columbus. Plants for cultivation were brought to Spainin 1558, and by 1586 smoking had become a general practice in west-ern Europe. The first commercial shipments were made from Virginiain 1618, the growing of cultured varieties having begun in 1612.Smoking of tobacco was practiced by the Indians from Canada toPatagonia, and the natives of Haiti used powdered tobacco leaf assnuff under the name of cohoba. Like Indian corn, the tobacco planthad been domesticated for centuries, and the original wild ancestor ofthe plant is not known. Some Indian tribes, such as the Tobacco nationof southwest Ontario, specialized in the growing of tobacco types.

The quality of the tobacco leaf varies greatly with the soil and cli-mate, the care of the plant, and the curing of the leaf; the nicotine con-tent develops in the curing process. The narcotic effects are due to thealkaloid nicotine, C10H14N2, a complex pyrrolidine, which is a heavy,water-white oil. The nicotine is absorbed through the mucous mem-branes of the nose and throat. The aroma and flavor come from theessential oils in the leaf developed during fermentation and curing. The more harmful effects to the eyes and respiratory system come fromthe pyridine C5H5N, a toxic aromatic compound that also occurs incoal tar, and from other elements of the smoke and not from the alka-loid. The burning of the tars may also produce carcinogen compoundswhich are complex, condensed, benzene-ring nuclei injurious to tissues.

Although N. tabacum is a less hardy plant than N. rustica, it adaptsitself to a wide variety of climates and soils, and the types generatedin given areas do not normally reproduce the same type in anotherarea. The variety developed in the Near East, known as Turkishtobacco and valued as an aromatic blend for cigarettes, is a smallplant with numerous leaves only about 3 in (7.6 cm) long, while theAmerican tobaccos grown from the same species have leaves up to 3 ft(0.9 m) long. The nicotine content of Turkish tobacco is from 1 to 2%,while that of flue-cured Virginia tobacco is 2.5 to 3%, and that of bur-ley and fire-cured American types is up to 4.5%. Perique, a strong,black tobacco much used in French and British pipe mixtures, is culti-vated only in a small area of southern Louisiana. Other tobaccosbrought into the area become perique in the second year, but whentransplanted back, they do not thrive. N. rustica was the first tobaccogrown in Virginia, but the tobacco now grown in the area and knownas Virginia tobacco is N. tabacum brought from the West Indies, but

972 TOBACCO




now differing in type from West Indian tobacco. Makhorka tobacco,a black, air-cured type grown in Russia and Poland and very high innicotine, is from N. rustica. Strong, black, highly fermented tobaccoshigh in nicotine, and considered as inferior in the United States, arepreferred in France and some other countries.

Types of tobacco are based on color, flavor, strength, and methods ofcuring and fermentation, while grades are based on size, aroma, andtexture, but the geographical growing area also determines character-istics. Commercial purchasing is done by the area and the Departmentof Agriculture type classification: fire-cured, dark air-cured, flue-cured,cigar wrapper, cigar binder, cigar filler, burley, Maryland, and perique,all of which are from N. tabacum. Grading is done by specialists, and asingle area crop may produce more than 50 grades. In the manufac-ture of cigarettes, blending is done to attain uniformity, and some ofthe flavor and aroma may be from added ingredients. Air-curedtobaccos are alkaline, while flue-cured tobaccos are acid and thenicotine is less readily given off. N. rustica may contain as high as 10%nicotine and is thus more desirable for insecticide use or for theextraction of nicotine, but some strains of N. tabacum have been devel-oped for smoking with as little as 0.3% nicotine.

Tobacco seed oil has an iodine value of 140 to 146 and is a valu-able drying oil, but the production is low because the seed heads aretopped in cultivation and seeds are developed only on the suckergrowths. Tobacco sauce, used for flavoring chewing and smokingtobaccos, contains up to 10% nicotine, but since the nicotine is notdesired in the flavoring, it is usually extracted for industrial use.Nicotine can be oxidized easily to nicotinic acid and to nicotinoni-trile, both of which are important as antipellagra vitamins. Most ofthe nicotine used for insecticide is marketed as nicotine sulfate inwater solution containing 40% nicotine. It is used as a sheep dip andas a contact insecticide. Tobacco dust is used for the control of plantlice. Anabasine, obtained in Russia from the Asiatic shrub Anabasisaphylla, has the same chemical composition as nicotine and is an iso-mer of nicotine. It is marketed in the form of a solution of the sulfateas an insecticide. It can also be obtained from N. glauca, a wild treetobacco native to Mexico and the southeastern United States, or ismade synthetically under the name of neonicotine.

TOLU BALSAM. A yellowish-brown, semisolid gum with a pleasantaromatic odor and taste, obtained from the tree Myroxylon balsa-mum, or Toluifera balsamum, of Venezuela, Colombia, and Peru. It isused in medicine, chiefly in cough syrups, and as a fixative in per-fumes. A soft, tenacious, resinous substance that hardens on keeping,

TOLU BALSAM 973




it is a mixture of free cinnamic and benzoic acids. Balsam of Peru,or black balsam, is a reddish-brown, viscous, aromatic liquid frombark of the tall tree M. pereirae of El Salvador. It is used in coughmedicines and skin ointments, as an extender for vanilla, and as afixative in perfumes. Some white-colored balsam is also obtained fromthe fruit of the tree. Peru balsam contains benzyl benzoate, benzylcinnamate, and some vanillin. Styrax is an aromatic balsam fromLiquidambar orientalis, and Zanthorrhoea balsams are acaroidresins from the X. australis tree. It is used as a perfumery substitutefor Peru balsam and Styrax.

TOLUOL. Also called toluene, methyl benzene, and methyl ben-zol. A liquid of composition C6H5CH3, resembling benzene but with adistinctive odor. It is obtained as a by-product from coke ovens andfrom coal tar. It occurs also in petroleum, with from 0.20 to 0.70% inTexas crude oil, which is not sufficient to extract. But toluol may beproduced by dehydrogenation of petroleum fractions. It is used as asolvent, and for making explosives, dyestuffs, and many chemicals,and in aviation gasoline to improve the octane rating. Industriallypure toluol from coal tar distills off between 227 and 235°F (108.6 and112.6°C), and is a water-white liquid with a specific gravity of 0.864 to0.874, flash point 35 to 40°F (2 to 4°C), and freezing point about139°F (95°C). The fumes are poisonous. Nitration grades are atleast 99.9% pure, and are used in synthesizing adhesives, agriculturalchemicals, coatings, and in textiles. Such a material is UnocalChemicals’ Amsco. B&J Brand, from Burdick & Jackson, is ultra-high purity and contains very low-luminescence impurities for liquidscintillation counters. It is also used for dissolving polymers for gelpermeation chromatography, and has low residues in pesticide residueanalyses. Monochlorotoluene, used as a solvent for rubber and syn-thetic resins, is a colorless liquid of composition CH3C6H4Cl, boiling atabout 320°F (160°C) and freezing at 49°F (45°C). T oil is a sulfurtoluene condensation product made under a British patent and usedas a plasticizer for chlorinated rubber. Notol No. 1, of NevilleChemical Co., is a coal tar hydrocarbon high in aromatics used as asubstitute for toluol as a lacquer solvent. The specific gravity is 0.825and the boiling point between 177 and 280°F (81 and 138°C). Tollac,of the same company, is another hydrocarbon substitute for toluol.Methyl cyclohexane, C6H11CH3, is a water-white liquid with a dis-tilling range of 212 to 217°F (100 to 103°C), produced by hydrogenat-ing toluol. It is used as a solvent for oils, fats, waxes, and rubbers.Methyl cyclohexanol, C6H10CH3OH, another toluol derivative, isused as a cellulose ester solvent and as an antioxidant in lubricants. It

974 TOLUOL




is a straw-colored, viscous liquid distilling between 311 and 356°F (155and 180°C). Polyvinyl toluene is a methyl form of styrene. It is poly-merized with terphenyl stilbene to form plastic scintillators to countradiation isotopes.

TONKA BEAN. Called in northeastern Brazil cumarú bean. The ker-nel of the pit of the fruit of the sarrapia tree, Dipteryx odorata orCoumarouna odorata, of northern South America, used for the pro-duction of coumarin for flavoring and scenting. It has an aromaresembling vanilla. The trees often reach a height of 100 ft (30 m) andbegin to bear in 3 years. The fruit is like a mahogany-colored plum,but with a fibrous pulp. The pits, or nuts, contain a single shiny, blackseed 1 in (2.5 cm) or longer. The chief production is in Venezuela,Brazil, Colombia, Trinidad, and the Guianas. The tonka bean fromthe tree D. oleifera of Central America has an unpleasant odor. Beforeshipping, the beans are soaked in rum or alcohol to crystallize thecoumarin. The ground beans are again soaked in rum, and the aro-matic liquid is used to spray on cigarette tobacco. The coumarinextract is also used as a perfume or flavor in soaps, liqueurs, and con-fectionery. The essential oil produced from the seed is called cumarúoil. A substitute for tonka bean is deer’s tongue leaf, which is thelong leaf of the herb Trilisa odoratissima, growing wild on the edgesof swamps from Carolina to Florida. The leaf has a strong odor ofcoumarin when dry, and contains coumarin. It is used in cigarettemanufacture, in flavoring, and to produce synthetic vanilla. It is alsoa normal constituent of lavender oil.

TOOL STEELS. Steels used mainly for cutters in machining, shear-ing, sawing, punching, and trimming operations, and for dies,punches, and molds in cold- and hot-forming operations. Some arealso occasionally used for nontool applications. Tool steels are primar-ily ingot-cast wrought products, although some are now also powder-metal (PM) products. Regarding PM products, there are two kinds: (1)mill products, mainly bar, produced by consolidating powder into“ingot” and reducing the ingot by conventional thermomechanicalwrought techniques, and (2) end-product tools, produced directly frompowder by pressing and sintering techniques. There are seven majorfamilies of tool steels as classified by the American Iron and SteelInstitute (AISI): (1) high-speed tool steels, (2) hot-work tool steels, (3)cold-work tool steels, (4) shock-resisting tool steels, (5) mold steels, (6)special-purpose tool steels, and (7) water-hardening tool steels.

High-speed tool steels are subdivided into three principalgroups or types: the molybdenum type, designated M1 to M46; the

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tungsten type (T1 to T15); and the intermediate molybdenum type(M50 to M52). Virtually all M types, which contain 3.75 to 9.5%molybdenum, also contain 1.5 to 6.75 tungsten, 3.75 to 4.25chromium, 1 to 3.2 vanadium, and 0.85 to 1.3 carbon. M33 to M46also contain 5 to 8.25% cobalt; and M6, 12% cobalt. The T types,which are molybdenum-free, contain 12 to 18% tungsten, 4 to 4.5chromium, 1 to 5 vanadium, and 0.75 to 1.5 carbon. Except for T1,which is cobalt-free, they also contain 5 to 12% cobalt. Both M50 andM52 contain 4% molybdenum and 4 chromium; the former also con-tains 0.85% carbon and 1 vanadium, the latter 0.9 carbon, 1.25 tung-sten, and 2 vanadium.

Although the tungsten types were developed first, around the turnof the century, the molybdenum types, developed in the 1930s whentungsten was scarce, are now by far the most widely used, and manyof the T types have M-type counterparts. All of the high-speed toolsteels are similar in many respects. They all can be hardened to atleast Rockwell C 63, have fine grain size, and have deep-hardeningcharacteristics. Their most important feature is hot hardness: Theyall can retain a Rockwell C hardness of 52 or more at 1000°F (538°C).The M types, as a group, are somewhat tougher than the T type atequivalent hardness; but otherwise, mechanical properties of the twotypes are similar. Cobalt improves hot hardness, but at the expense oftoughness. Wear resistance increases with increasing carbon andvanadium contents. The M types have a greater tendency to decar-burization and, thus, are more sensitive to heat treatment, especiallyaustenitizing. Many of the T types, however, are also sensitive in thisrespect, and they are hardened at somewhat higher temperatures.The single T type that stands out today is T-15, which is rated as thebest of all high-speed tool steels from the standpoint of hot hardnessand wear resistance. Typical applications for both the M type and Ttype include lathe tools, end mills, broaches, chasers, hobs, millingcutters, planar tools, punches, drills, reamers, routers, taps, andsaws. The intermediate M types are used for somewhat similar cut-ting tools but, because of their lower alloy content, are limited to less-severe operating conditions.

Hot-work tool steels are subdivided into three principal groups:(1) the chromium type (H10 to H19), (2) the tungsten type (H21 toH26), and (3) the molybdenum type (H42). All are medium-carbon(0.35 to 0.60%) grades. The chromium types contain 3.25 to 5.00%chromium and other carbide-forming elements, some of which, suchas tungsten and molybdenum, also impart hot strength, and vana-dium, which increases high-temperature wear resistance. The tung-sten types, with 9 to 18% tungsten, also contain chromium, usually 2

976 TOOL STEELS




to 4, although H23 contains 12% of each element. The one molybde-num type, H42, contains slightly more tungsten (6%) than molybde-num (5), and 4 chromium and 2 vanadium. Typical applicationsinclude dies for forging, die casting, extrusion, heading, trim, piercingand punching, and hot-shear blades. Magnadie, from Latrobe Steel,is a 5 chromium, air-hardening steel with better toughness than H13steel and comparable elevated-temperature strength and hardness.Toughness ranges from 6 to 10 ft. lb (8 to 14 J), tensile yield strengthfrom 160,000 to 200,000 lb/in2 (1100 to 1380 MPa), and Rockwell Chardness from 40 to 48.

There are also three major groups of cold-work tool steels: (1)high-carbon (1.5 to 2.35%); high-chromium (12), which are designatedD2 to D7; (2) medium-alloy air-hardening (A2 to A10), which may con-tain 0.5 to 2.25% carbon, 0 to 5.25 chromium, 1 to 1.5 molybdenum, 0to 4.75 vanadium, 0 to 1.25 tungsten, and, in some cases, nickel, man-ganese or silicon, or nickel and manganese; and (3) oil-hardeningtypes (O1 to O7). They are used mainly for cold-working operations,such as stamping dies, draw dies, and other forming tools as well asfor shear blades, burnishing tools, and coining tools. Shock-resis-tant tool steels (S1 to S7) are, as a class, the toughest, althoughsome chromium-type hot-work grades, such as H10 to H13, are some-what better in this respect. The S types are medium-carbon (0.45 to0.55%) steels containing only 2.50 tungsten and 1.50 chromium (S1),only 3.25 chromium and 1.40 molybdenum (S7), or other combina-tions of elements, such as molybdenum and silicon, manganese andsilicon, or molybdenum, manganese, and silicon. Typical uses includechisels, knockout pins, screw driver blades, shear blades, punches,and riveting tools.

There are three standard mold steels: P6, containing 0.10% car-bon, 3.5 nickel, and 1.5 chromium; P20, 0.35 carbon, 1.7 chromium,and 0.40 molybdenum; and P21, 0.20 carbon, 4 nickel, and 1.2 alu-minum. P6 is basically a carburizing steel produced to tool-steel qual-ity. It is intended for hubbing—producing die cavities by pressingwith a male plug—then carburizing, hardening, and tempering. P20and P21 are deep-hardening steels and may be supplied in hardenedcondition. P21 may be carburized and hardened after machining.These steels are tough but low in wear resistance and moderate inhot hardness, P21 being best in this respect. All three are oil-harden-ing steels, and they are used mainly for injection and compressionmolds for forming plastics, but they also have been used for die-cast-ing dies. RA40 mold steel, from A. Finkl & Sons Co., is a double-vac-uum-melted, precipitation-hardened grade for 40 Rockwell Chardness that requires no heat treatment and features better

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machinability than the P20 grade. It contains 3 nickel, 1.5 man-ganese, 1 copper, 1 aluminum, 0.3 silicon, and 0.15 carbon. It can beused at temperatures up to 930°F (500°C) and is recommended formolding plastics and elastomers requiring greater wear resistancethan that of P20.

Special-purpose tool steels include L2, containing 0.50 to 1.10%carbon, 1.00 chromium, and 0.20 vanadium; and L6, having 0.70 car-bon, 1.5 nickel, 0.75 chromium, and sometimes 0.25 molybdenum. L2is usually hardened by water quenching and L6, which is deeper-hardening, by quenching in oil. They are relatively tough and easy tomachine and are used for brake-forming dies, arbors, punches, taps,wrenches, and drills. The water-hardening tool steels include W1,which contains 0.60 to 1.40% carbon and no alloying elements; W2,with the same carbon range and 0.25 vanadium; and W5, having 1.10carbon and 0.50 chromium. All are shallow-hardening and the leastqualified of tool steels in terms of hot hardness. However, they can besurface-hardened to high hardness and thus can provide high resis-tance to surface wear. They are the most readily machined tool steels.Applications include blanking dies, cold-striking dies, files, drills,countersinks, taps, reamers, and jewelry dies.

Bethlehem Lukens, makes a series of prehardened plate steels, des-ignated MTD 1 to MTD 4, which are somewhat similar in compositionto 41XX chromium-molybdenum steels. The 18% nickel maragingsteels, although developed for structural applications, are also usedas die-casting dies and metal- and plastic-forming dies. And TeledyneVasco makes matrix steels, which are said to be matrix compositionsof M2 and M42 high-speed tool steels with less carbon and alloy con-tent. They are used for extrusion, compacting, and thread-rollingdies, and punches and saw blades. Although most die steels arewrought steels and some are made from powder metal, cast steels arealso used for various applications.

Although many tool steels are typically wrought products, produc-ers have turned increasingly to the use of powder metals for the start-ing stock. PM tool steels pertain mainly to high-speed grades forcutting, or machining, applications but several grades for formingapplications are also made from powder. Advantages attributed to thePM steels stem largely from improved microstructural control forcompositional uniformity and freedom from segregation. They canprovide superior machinability in the annealed condition, bettergrindability in the hardened and tempered condition without loss ofabrasion resistance, greater toughness, better dimensional stabilityin heat treatment, and amenability to high alloy content to promotewear resistance and increase cutting or forming performance.

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PM tool steels include the Micro-Melt alloys from CarpenterTechnology and the CPM alloys from Crucible Materials Corp.Micro-Melt alloys include AISI standard grades A11, M3, M4, M42,M48, and T15 plus specials like Micro-Melt 9 and 10, HS-30, andMaxamet. Alloys 9 and 10 are high-vanadium (8.75 and 9.75%,respectively), tungsten- and cobalt-free, 5.25 chromium, molybdenum(1.35 and 1.3%), and carbon (1.75 and 2.45%) steels. HS-30 tool steelcontains 8.5 cobalt, 6.25 tungsten, 5 molybdenum, 4.2 chromium, 3.1vanadium, and 1.27 carbon. Maxamet tool steel, with 1.3 tungsten,9 cobalt, 6 vanadium, 5 chromium, and 2.15 carbon, attains 70Rockwell C hardness, and cutting tools made of the steel canapproach the cutting speeds of carbide tools. Similarly, CPM gradescan pertain to standard grades, for example, M3, M4, M48, M62, andT15, or to specials such as CPM Rex grades, CPM 3V to 18V, Vanadistool steels, and K190 PM tool steel. V grades include both hot- andcold-work types. CPM Rex 121 tool steel, the highest-carbon (3.4%)CPM tool steel, contains 10.5 tungsten, 9.5 vanadium, 9.5 cobalt, 5.5molybdenum, and 4 chromium. It can attain 70 to 72 Rockwell Chardness, and features excellent temper resistance and hot hardnessto 1200°F (650°C) and superior resistance to abrasive and adhesivewear. At this hardness, the steel contains about 29% (by volume) pri-mary carbides, mainly the vanadium-rich MC kind for maximumwear resistance. It is intended primarily for cutters performing high-speed machining operations.

To prolong tool life, tool-steel end products, such as mills, hobs,drills, reamers, punches, and dies, can be nitrided or coated in severalways. Oxide coatings, imparted by heating to about 1050°F (566°C)in a steam atmosphere or by immersion in aqueous solutions ofsodium hydroxide and sodium nitrite at 285°F (140°C), are not aseffective as traditional nitriding, but do reduce friction and adhesionbetween the workpiece and tool. The thickness of the coating devel-oped in the salt bath is typically less than 0.0002 in (0.005 mm), andits nongalling tendency is especially useful for operations in whichfailure occurs in this way. Hard-chromium plating to a thickness of0.0001 to 0.0005 in (0.0025 to 0.0127 mm) provides a hardness ofDPH 950 to 1,050 and is more effective than oxide coating, but theplate is brittle and, thus, not advisable for tools subject to shockloads. Its toughness may be improved somewhat without substan-tially reducing wear resistance by tempering at temperatures below500°F (260°C), but higher tempering temperatures impair hardness,thus wear resistance, appreciably. An antiseize iron sulfide coatingcan be applied electrolytically at 375°F (191°C) using a bath ofsodium and potassium thiocyanate. Because of the low temperature,

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the tools can be coated in the fully hardened and tempered conditionwithout affecting hardness. Tungsten carbide is another effectivecoating. One technique, developed by Rocklin Manufacturing andcalled Rocklinizing, deposits 0.0001 to 0.0008 in (0.0025 to 0.0203mm) of the carbide using a vibrating arcing electrode of the materialin a handheld gun. Titanium carbide and titanium nitride are thelatest coatings. The nitride, typically 0.0003 in (0.008 mm) thick, hasstirred the greatest interest, although the carbide may have advan-tages for press tools subject to high pressure. In just the past fewyears, all sorts of tools, primarily cutters but also dies, have been tita-nium-nitride-coated, which imparts a gold- or brasslike look. Thecoating can be applied by chemical vapor deposition (CVD) at1750 to 1950°F (954 to 1066°C) or by physical vapor deposition(PVD) at 900°F (482°C) or less. Thus, the PVD process has an advan-tage in that the temperature involved may be within or below thetempering temperature of the tool steels so that the coating can beapplied to fully hardened and tempered tools. Also, the risk of distor-tion during coating is less. Titanium nitride coaters includeAerobraze, Multi-Arc Vacuum Systems, Scientific Coatings, StarCutter, Sylvester, and Ti-Coating. Another method being used to pro-long tool life is to subject the tools to a temperature of 320°F(196°C) for about 30 h. The cryogenic treatment, which has beencalled Perm-O-Bond and Cryo-Tech by Materials Improvement, issaid to rid the steel of any retained austenite—thus the improved toollife. Others in this business include Amcry, Endure, and 3XKryogenics.

TRAGACANTH GUM. An exudation of the shrub Astragalus gummiferof Asia Minor and Iran, used in adhesives or for mucilage, for leatherdressing, for textile printing, and as an emulsifying agent. To obtain thegum, a small incision is made at the base of the shrub, from whichthe juice exudes and solidifies into an alteration product, not merely thedried juice. The gum derived from the first day’s incision, known asfiori, is the best quality and is in clear, fine ribbons or white flakes. Thesecond incision produces a yellow gum known as biondo. The thirdincision produces the poorest quality, a dark gum known as sari. Rainyweather during the incision period may cause a still inferior product.Tragacanth is insoluble in alcohol but is soluble in alkalies and swellsin water. Karaya gum from southern Asia is from various species ofSterculia trees, especially S. urens, of India. It is also known asIndian gum, Indian hog gum, and hog tragacanth. The stickygum is dried, and the chunks are broken and the pieces sorted bycolor. A single chunk may have colors varying from clear white to darkamber and black. The color is caused by tannin or other impurities.

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The No. 3 grade, the lowest, has up to 3% insoluble impurities. Thegum is marketed in flakes and as a white, odorless, 150-mesh powder.The chief constituent is galactan. In general, the gum is more acidthan tragacanth and is likely to form lumpy gels unless finely ground.It is widely used as a thickening and suspending agent for foodstuffs,drugs, cosmetics, adhesives, and textile finishes. Gum tragacynththoroughly mixed with glycerin and water produces a thick paste, tra-gacynth glycerite, a useful excipient to bind tablet masses. For oralingestion, suspensions of gum tragacynth have been formulated. Onesuch product is a suspension of procaine penicillin. In hair lotion inwhich there is 10% isopropanol, gum tragacynth is able to withstandthe alcohol without precipitation. It is also a thickener of the aqueousphase in oil-in-water systems, resulting in shelf-stable emulsions.Regular as well as low-calorie salad dressings, such as ThousandIsland, French, and Roquefort, are such oil-in-water emulsions.The low-calorie versions have higher amounts of gum tragacynth, toprovide the body that oil traditionally gives the regular dressing.Tragacynth gums, Type A.10, Type W, and Type L, are pharmaceuti-cal grades in powder form, produced by Meer Corp.

The granules of water-soluble gums, such as karaya, tragacanth,and acacia, are swelled by water and dispersed in water in micro-scopic particles to form cells or filamentlike structures which hold thewater like a sponge and will not settle out. This type of colloidal dis-persion is called a hydrasol, and when thick and viscous is called agel. From 2 to 3% of karaya or other gum will form a gel in water.These gums will gel in cold water, while gelatin requires hot water fordissolving. In a gel there is continuous structure with molecules form-ing a network, while in a sol the particles are in separate suspensionand a sol is merely a dispersion. Some dispersions, such as albumen,cross-link with heat; others, like guar gum, cross-link with alkalies;still others, like pectin, link with sugar and an acid. Gums with weaksurface forces form weak gels which are pastes or mucilage, and ahigh concentration is needed to produce a solid. Karaya has greatswelling power, and is used in medicine as a bulk laxative. Ghattigum, from the abundant tree Anogeissus latifolia of India, is entirelysoluble in water to form a viscous mucilage. It is twice as effective asgum arabic as an emulsifier, but is less adhesive. It comes in colorlessto pale-yellow tears of vitreous fracture, called also Indian gum, andis used in India for textile finishing. Aqualized gum, of GlycoProducts Co., Inc., is tragacanth or karaya chemically treated to givemore rapid solubility. Water-soluble gums are also produced syntheti-cally. Polyox gum, of Union Carbide Chemicals Co., is a polymer ofpolyethylene oxide containing carboxylic groups giving water solubil-ity when the pH is above 4.0. In paper coating with ammonia, the

TRAGACANTH GUM 981




ammonia evaporates to leave a water-insoluble, grease-resistant filmthat is heat-sealing. It is also used in latex paints and in cosmetics.

Another water-soluble gum which forms a true gel with a continuousbranched-chain molecular network is okra gum, produced as a 200-mesh tan powder. It is edible and is used for thickening and stabilizingfoods and pharmaceuticals. It is also used in plating baths for bright-ening nickel, silver, and cadmium plates. It is extracted from the podsof the okra, Hibiscus esculentus, a plant of the cotton family. In thesouthern states the pods, called gumbo, are used in soups. The refinedgum, after extraction of the oils and sugars, contains 40.4% carbon, 6.1hydrogen, and 2.1 nitrogen, with the balance insoluble cellulose.

TRIPOLI. A name given to finely granulated, white, porous, siliceousrock, used as an abrasive and as a filler. True tripoli is an infusorial,diatomaceous earth known as tripolite, and is a variety of opal, oropaline silica. In the abrasive industry it is called soft silica. It isquarried in Missouri, Illinois, eastern Tennessee, and Georgia.Pennsylvania rottenstone is not tripoli, although it is often classifiedwith it. The material marketed for oil-well drilling mud under thename of Opalite, is an amorphous silica. The Missouri tripoli rangesin color from white to reddish, and the crude rock has a porosity of45% and contains 30% or more of moisture. It is air-dried and thencrushed and furnace-dried. Tripoli is used in massive form for themanufacture of filter stones for filtering small supplies of water.Missouri tripoli is also used for the manufacture of foundry parting.Finely ground tripoli, free from iron oxide, is used as a paint filler andin rubber. The grade of tripoli known as O.G. (once ground) is used forbuffing composition, D.G. (double ground) for foundry partings, andthe air-float product for metal polishes. Tripoli grains are soft, porous,and free from sharp cutting faces, and they give a fine polishingeffect. It is the most commonly used polishing agent. The word silex,which is an old name for silica and is also used to designate the pul-verized flint from Belgium, is sometimes applied to finely groundwhite tripoli employed as an inert filler for paints. Much Illinois fine-grained tripoli is used for paint, and for this purpose it should be freefrom iron oxide. Rottenstone is a soft, friable, earthy stone of lightgray to olive color, used as an abrasive for metal and wood finishing.It resembles Missouri tripoli and is derived from the weathering ofsiliceous-argillaceous limestone, with generally from 80 to 85% alu-mina, 4 to 15 silica, and 5 to 10 iron oxides. Rottenstone was largelyimported from England, but one variety is found in Pennsylvania. Itis finely ground and is marketed either as a powder or molded intobricks. The latter form is used with oil on rag-wheel polishing. A250-mesh powder is used as a filler in molding compounds.

982 TRIPOLI




TRISODIUM PHOSPHATE. A white, crystalline substance of composi-tion Na3PO4 12H2O, also known as phosphate cleaner, used insoaps, cleaning compounds, plating, textile processing, and boilercompounds. The commercial grade is not less than 97% pure, withtotal alkalinity of 16 to 19% calculated as Na2O. The anhydroustrisodium phosphate is 2.3 times as effective as the crystalline form,but requires a longer time to dissolve. Disodium phosphate is awhite, crystalline product of composition Na2HPO4 12H2O used forweighting silk, boiler treatment, cheese making, and cattle feeds.The medicinal, or USP, grade has only seven molecules of water andhas a different crystal structure. The commercial grade is 99.4%pure and is readily soluble in water. Trisodium phosphate hemi-hydrate is a granular, crystalline grade from FMC Corp. fordegreasing and water conditioning. Monosodium phosphate ismade by reacting soda ash with phosphoric acid in molecular pro-portions; it is used in similar applications to the disodium variety.Sodium tetraphosphate, Na6P4O13, contains 39.6% Na2O and 60.4P2O5. It is the sodium salt of tetraphosphoric acid and is mar-keted in beads that are mildly alkaline and highly soluble in water.The specific gravity is 2.55 and it melts at 1,112°F (600°C). It isused in the textile industry as a water softener and to acceleratecleansing operations. It removes lime precipitation and sludge andsaves soap. Quandrafos, of American Cyanamid Co., used toreplace quebracho for reducing the viscosity of oil-well drilling mud,is sodium tetraphosphate, containing 63.5% P2O5. It makes the cal-cium and magnesium compounds inactive, and 0.06% of the mater-ial controls 16.1% of water in reducing viscosity. It also gives smoothflow with minimum water in paper coating and textile printing.Metafos, of the same company, has a higher percentage of P2O5—67%—and a lower pH, for use in textile printing where low alkalin-ity is needed. Sodium pyrophosphate, Na4P2O7, is added to soappowders to increase the detergent effect and the lathering. It is alsoused in oil-drilling mud. The crystalline form, Na4P2O7 10H2O, isvery soluble in water and is noncaking, and it is used in householdcleaning compounds. Sodium tripolyphosphate, Na5P3O10, is awater-soluble, white powder used as a detergent, a water softener,and a deflocculating agent in portland cement to govern the viscos-ity of the shale slurry without excessive use of water. Large quanti-ties of these phosphates are used in the processing of chemicals,textiles, and paper; and since they are toxic contaminants of groundand surface waters, mill wastes must be deactivated before they aredischarged. The use of phosphates in detergents and soap powdershas been banned in many areas since they lead to rapid algalgrowth in surface waters.

TRISODIUM PHOSPHATE 983




TULIPWOOD. Also called yellow poplar, whitewood, and canarywhitewood, the wood of the tree Liriodendron tulipifera of Canadaand the eastern United States. The tree grows to a height of 250 ft(76 m) and to diameters of more than 10 ft (3 m). It is used for furni-ture, veneer, millwork, toys, woodenware, boxes, crates, and pulp-wood. Owing to its close texture and even coefficient of expansion, ithas been used for expansion blocks in humidity regulators. It is yel-lowish, soft, and durable. The density is about 30 lb/ft3 (481 kg/m3).The lumber may be mixed with cucumber magnolia, Magnoliaacuminata, and evergreen magnolia, M. grandifolia, but magnoliawoods are lighter in color.

TUNG OIL. A drying oil which has almost double the rapidity of lin-seed oil. It is used for enamels and varnishes; in brake linings, plasticcompounds, and linoleum; and for making pigment for India ink.Tung oil is pressed from the seeds of Aleurites montana and A. fordii.The names wood oil and China wood oil are loosely and erro-neously used to designate tung oils, but true wood oil is an oleoresinfrom the Keruing tree of Malaya used for waterproofing and caulk-ing boats, while tung oil is never from the wood. The oil has a power-ful purgative action, and the Chinese word means stomach. TheChinese tung oil is from the nuts of the tree A. montana, the Chinawood oil tree, and A. fordii. The latter tree is hardier than A. mon-tana, which requires a hot climate. The American tung oil is from thenuts of the tree A. fordii of the Gulf states, which gives an annualproduction of about 30 lb (14 kg) of oil per tree. The tree grows to aheight of 25 ft (8 m) and bears for 5 years. The seeds, or nuts, contain50 to 55% oil. This tree is also grown in South Africa and Argentina.

The color of tung oil varies from golden yellow to dark brownaccording to the degree of heat used in extraction. It has a pungentodor resembling that of bacon fat. A good grade of raw tung oil shouldhave a specific gravity between 0.934 and 0.940, a saponificationvalue of 190, and an iodine value of 163. The oil contains about 72%eleostearic acid, which has a very high iodine value, 274, and givesto the oil a greater drying power than is indicated by the iodine valueof the oil itself. The oil has the property of drying throughout at auniform rate, instead of forming a skin as linseed oil does; but it driesflat instead of glossy, like linseed oil, and is inclined to produce awrinkled surface. It is mixed with rosin, since rosin has great affinityfor it, and the two together are suitable for gloss varnishes. In combi-nation with other drying oils, it improves water and alkali resistance,and is used mainly in quick-drying enamels and varnishes. The oilfrom A. montana, or mu oil, has a higher percentage of eleostearicacid than that from A. fordii. The Japanese tung oil is from the

984 TUlLIPWOOD




nuts of the larger tree A. cordata. The oil is superior to Chinese tungoil and is seldom exported. It does not gelatinize as Chinese tung oildoes, when heated. It is used in Japan for varnishes, waterproofingpaper, and soaps. The saponification value is 193 to 195, iodine valueof 149 to 159, and specific gravity 0.934 to 0.940. The kernels of thenuts yield about 40% oil. The tree is grown also in Brazil and thrivesin hot climates. Candlenut oil is from the seed nuts of A. moluccanaof Oceania and southern Asia. It received its name from the fact thatthe Polynesians used the nuts as candles to light their houses. The oilis variously known as kukui, kekune, and lumbang, and as anartist’s paint, oil is called walnut oil or artist’s oil. The nut resem-bles the walnut but has a thicker shell. The oil has a specific gravityof 0.923, iodine value 165, and is between linseed and soybean oil inproperties. It is high in linoleic and linolenic acids. The varietyknown as soft lumbang oil, or bagilumbang oil, from the tree A.trisperma of the Philippines, resembles tung oil and is high ineleostearic acid. The chief production of lumbang oil is in the FijiIslands.

The Safflower, Carthamus tinctorius, is grown in California,France, and India, and in the latter country it is grown on a largescale for seeds, which yield up to 35% of the clear, yellowish saf-flower oil used in paints, leather dressings, in the manufacture ofnonyellowing alkyd resins, and for foods. The oil has a high content,73%, of linoleic acid, the highest of essential polyunsaturated acids ofany vegetable food oil. It is odorless, with a bland taste, has a specificgravity of 0.915, and an iodine value of 150. Safflower 22, of PacificVegetable Oil Corp., is a conjugated paint oil made by isomerizing saf-flower oil. It has a rapid drying rate, color retention, and an ability toproduce wrinkled finishes by adjustment of the amount of drier. Itcan thus replace tung oil. It takes up maleic anhydride readily, and isused for making modified alkyd finishes. Wecoline SF, of DrewChemical, is a concentrate of safflower fatty acids with 67.3% linoleicacid and only 0.2 linolenic acid, for compounding in coatings. Saff, ofAbbott Laboratories, is an emulsion of safflower oil used as a drug tolower blood cholesterol. Refined and deodorized oil shows 2.8 106

lb (1.3 mg) of “cholesterol-equivalent” sterols per 0.22 lb (100 g) of oil.The heads of the plant are dried and used as food colors, for dyeingtextiles, and for cosmetic rouge.

TUNGSTEN AND TUNGSTEN ALLOYS. A heavy, white metal, symbol W,with a specific gravity of 19.6, a density of 0.697 lb/in3 (19,290 kg/m3),the highest melting point, 6170°F (3410°C), of all metals and a tensilestrength of 50,000 lb/in2 (345 MPa) at 2500°F (1370°C). Wolframiteis the chief ore of the metal tungsten. Its composition is (FeMn)WO3.

TUNGSTEN AND TUNGSTEN ALLOYS 985




986 TUNGSTEN AND TUNGSTEN ALLOYS

When the manganese tungstate is low, the ore is called ferberite;when the iron tungstate is low, it is called hübnerite. The ore is con-centrated by gravity methods to a concentrate containing 60 to 65%tungstic oxide, WO3. To extract pure WO3 from the concentrate, it isfused with sodium carbonate, Na2CO3, to form sodium tungstate,Na2WO3, which is dissolved in water. When an acid is added to thesolution, the WO3 precipitates out as a yellow powder. The metallictungsten is obtained by reduction and is then pressed into bars andsintered. Wolframite occurs usually bladed or columnar in form. Ithas a specific gravity of 7.2 to 7.5, a Mohs hardness of 5, a black color,and a submetallic luster. It is found in the mountain states, Alaska,China, and Argentina, but it also widely distributed in various partsof the world in small quantities. Chinese wolfram concentratescontain 65% tungstic oxide; the Arizona concentrates contain an aver-age of 67%. California and Nevada concentrates are scheelite contain-ing from 60 to 67% tungstic oxide. The sanmartinite of Argentina isa variety containing zinc.

Tungsten has a wide usage in alloy steels, magnets, heavy metals,electric contacts, rocket nozzles, and electronic applications. It is alsoused for x-ray and gamma-ray shielding and wear-resistant surfaces,electroplates providing Vickers 700 or greater hardness. Tungstenresists oxidation at very high temperatures and is not attacked bynitric, hydrofluoric, or sulfuric acid solutions. Flame-sprayed coatingsare used for nozzles and other parts subject to heat erosion.Tungsten alloys are used for weights and counterbalances, radiationshielding, grinding tools, tooling, and high-temperature applications.Copper-tungsten composites and silver-tungsten compositesserve as resistance-welding die inserts, electrode facings, electricalcontacts, heat sinks, wear surfaces, and electrodes for electrical-dis-charge machining (EDM) and electrochemical machining.

Tungsten is usually added to iron and steel in the form of ferro-tungsten, made by electric-furnace reduction of the oxide with iron orby reducing tungsten ores with carbon and silicon. Standard gradeswith 75 to 85% tungsten have melting points from 3200 to 3450°F(1760 to 1899°C). Tungsten powder is usually in sizes from 200 to325 mesh, and may be had in a purity of 99.9%. Parts, rods, and sheetare made by powder metallurgy, and rolling and forging are done athigh temperature. The rolled metal may have a tensile strength ashigh as 500,000 lb/in2 (3,448 MPa) and a Brinell hardness of 290,whereas drawn wire may have a tensile strength to 590,000 lb/in2

(4,068 MPa). The tungsten powder is used for spray coatings for radia-tion shielding and for powder-metal parts. Tungsten wire is used forspark plugs and electronic devices, and tungsten filaments are usedin lamps. Tungsten wire as fine as 0.00018 in (0.00046 cm) is used in




TUNGSTEN AND TUNGSTEN ALLOYS 987

electronic hardware, and as thin as 0.0004 in (0.001 cm) for wireEDM. Tungsten whiskers, which are extremely fine fibers, are usedin copper alloys to add strength. Copper wire, which normally has atensile strength of 30,000 lb/in2 (207 MPa), will have a strength of120,000 lb/in2 (827 MPa) when 35% of the wire is tungsten whiskers.Tungsten yarns are made up of fine fibers of the metal. The yarnsare flexible and can be woven into fabrics. Continuous tungsten fila-ments, usually 394 to 591 in (10 to 15 m) in diameter, are used forreinforcement in metal, ceramic, and plastic composites. Finer fila-ments are used as cores, or substrates, for boron filaments.

The metal is also produced as arc-fused grown crystals, usually nolarger than 0.375 in (0.952 cm) in diameter and 10 in (25.4 cm) long,and worked into rod, sheet, strip, and wire. Tungsten crystals,99.9975% pure, are ductile even at very low temperatures, and wireas fine as 0.003 in (0.008 cm) and strip as thin as 0.005 in (0.013 cm)can be cold-drawn and cold-rolled from the crystal. The crystal metalhas nearly zero porosity, and its electrical and heat conductivities arehigher than those of ordinary tungsten. The normal electrical conduc-tivity is about 33% that of copper, but that of the crystal is 15%higher. The molecules of tungsten appear as body-centered cubes, butin the pure metal the atoms normally bond uniformly in six direc-tions, forming a double lattice so that each grain forms a true singlecrystal. At elevated temperatures, tungsten forms many compoundsin chemicals and alloys. One tungsten-aluminum alloy is a chemi-cal compound made by reducing tungsten hexachloride with moltenaluminum. Tungsten-rhenium alloys, in wire, rod, sheet, and platefrom Rhenium Alloys, Inc., include tungsten-26 rhenium, tungsten-25rhenium and tungsten-5 rhenium. The W-25Re alloy has a density of0.711 lb/in3 (19,680 kg/m3) and melts at 5522°F (3050°C). The electri-cal conductivity is 6% IACS, the ultimate tensile strength is 225,000lb/in2 (1,551 MPa), the elongation is 10%, and the tensile modulus is59,460,000 lb/in2 (410,000 MPa).

Mi-Tech Metals Inc. produces series of tungsten-based metals oralloys for various requirements. The HD tungsten Series, for high-density, high-strength applications, contains 90 to 97% tungsten, plusnickel, iron, or copper, or iron and molybdenum. Depending on grade,density ranges from 0.614 to 0.668 lb/in3 (17,000 to 18,500 kg/m3),hardness is 24 to 32 Rockwell C, ultimate tensile strength is 110,000to 125,000 lb/in2 (758 to 862 MPa), tensile yield strength is 80,000 to95,000 lb/in2 (552 to 655 MPa), and elongation is 4 to 10%. Also, thetensile modulus is 40 106 to 53 106 lb/in2 (276,000 to 365,000MPa), electrical conductivity is 13 to 17%, and most grades areslightly magnetic. Typical uses include crankshaft balancing, radia-tion shielding, rotating inertia members, ordnance parts, boring bars




988 TUNGSTEN CARBIDE

and grinding quills and dies for die casting, extrusion, and hot upset-ting. A CW tungsten-copper Series, with 68 to 80% tungsten andthe balance copper, is used for electrical-discharge and electrochemi-cal machining. Another, 74 tungsten-26 silver, is also used for EDM.Tungsten-copper grades, with 28 to 55% electrical conductivity, areused for resistance welding, resistance-welding electrode facings,flash-butt-welding dies, and hot upsetting dies. Other metals made bythe company are copper– or copper alloy–tungsten carbide andElecon tungsten-copper and tungsten-silver, tungstencarbide–silver, and molybdenum-silver electrical contact metals.There’s also the Thermitech tungsten-copper Series for heat-sinkapplications.

Cobalt-tungsten alloy, with 50% tungsten, gives a plate thatretains a high hardness at red heat. Tungsten RhC is a tungsten-rhenium carbide alloy containing 4% rhenium carbide. It is usedfor parts requiring high strength and hardness at high temperatures.The alloy retains a tensile strength of 75,000 lb/in2 (517 MPa) at3500°F (1927°C). Ammonium metatungstate, used for electroplat-ing, is a white powder of composition (NH4)6H2W12O40. It is readilysoluble in water and gives solutions of 50% tungsten content.Tungsten hexafluoride is used for producing tungsten coatings byvapor deposition. At a temperature of 900°F (482°C) the gas mixedwith hydrogen deposits a tungsten plate. Tungsten hexachloride,WCl6, is also used for depositing tungsten coatings at that tempera-ture in a hydrogen atmosphere. Smooth, dense tungsten plates canbe deposited from tungsten carbonyl, W(CO)6, at a temperature of302°F (150°C). The carbonyl is made by reacting the hexachloridewith carbon monoxide.

TUNGSTEN CARBIDE. An iron-gray powder of minute cubical crystalswith a Mohs hardness above 9.5 and a melting point of about 5400°F(2982°C). It is produced by reacting a hydrocarbon vapor with tung-sten at high temperature. The composition is WC, but at high heat itmay decompose into W2C and carbon, and the carbide may be a mix-ture of the two forms. Other forms may also be produced, such as W3Cand W3C4. Tungsten carbide is used chiefly for cutting tool bits andfor heat- and erosion-resistant parts and coatings.

Briquetting of tungsten carbide into usable form was firstpatented in Germany and produced by Krupp Works under thename of Widia metal. It is made by diffusing powdered cobaltthrough the finely divided carbide under hydraulic pressure, andthen sintering in an inert atmosphere at about 2732°F (1500°C).The briquetted material is ground to shape, and the pieces arebrazed into tools. They withstand cutting speeds from 3 to 10 times




those of high-speed steel, and will turn manganese steel with aBrinell hardness of 550, but are not shock-resistant. Pressed andsintered parts usually contain 3 to 20% cobalt binder, but nickelmay also be used as a binder. The compressive strengths may be ashigh as 700,000 lb/in2 (4,827 MPa) with rupture strengths to200,000 lb/in2 (1,379 MPa) or higher.

One of the earliest of the U.S. bonded tungsten carbides wasCarboloy, of General Electric Co., used for cutting tools, gages,drawing dies, and wear parts. The sintered materials have beensold under many trade names such as Dimondite, Firthite, andFirthaloy; Armide, of Armstrong Bros. Tool Co.; Wilcoloy; andBorium and Borod, of Stoody Co. But the carbides are now oftenmixed carbides. Carboloy 608 contains 83% chromium carbide, 2tungsten carbide, and 15 nickel binder. It is lighter in weight thantungsten carbide, is nonmagnetic, and has a Rockwell A hardness to93. It is used for wear-resistant parts and resists oxidation to2000°F (1092°C). Titanium carbide is more fragile, but may bemixed with tungsten carbide to add hardness for dies. Cutanit issuch a mixture. Kennametal K601, of Kennametal, Inc., for sealrings and wear parts, is a mixture of tantalum and tungsten car-bides without a binder. It has a compressive strength of 675,000lb/in2 (4,654 MPa), rupture strength of 100,000 lb/in2 (690 MPa),and Rockwell A hardness of 94. Kennametal K501 is tungstencarbide with a platinum binder for parts subject to severe heat ero-sion. Strauss metal, of Allegheny Ludlum Steel Co., is tungstencarbide. Tungsten carbide LW-1 is tungsten carbide with about6% cobalt binder used for flame-coating metal parts to give high-temperature wear resistance. Deposited coatings have a Vickershardness to 1,450 and resist oxidation at 1000°F (538°C).Tungsten carbide LW-1N, with 15% cobalt binder, has a muchhigher rupture strength, but the Vickers hardness is reduced to1,150. Metco 35C is a fine powder of tungsten carbide and cobaltfor flame spraying to produce a wear-resistant coating of carbide ina matrix of cobalt. GPX 9660, of Securamax International, is atungsten carbide and cobalt coating applied by flame spraying toincrease the wear resistance and, to some extent, the corrosionresistance of steel parts. A tungsten carbide and nickel formula-tion, GPX 9657, also increases wear resistance and provides bettercorrosion resistance. Tungsten carbide chemically bonded to a mod-ified nickel aluminide, developed at the U.S. Department ofEnergy’s Oak Ridge National Laboratory and patented by DowChemical and Martin Marietta Energy Systems, is harder and perhapsmore durable than tungsten carbide–cobalt in rock-, coal-, andmetal-cutting applications.

TUNGSTEN CARBIDE 989




TUNGSTEN STEEL. Any steel containing tungsten as the alloying ele-ment imparting the chief characteristics to the steel. It is one of theoldest of the alloying elements in steel, the celebrated ancientEastern sword steels having contained tungsten. Tungsten increasesthe hardness of steel, and gives it the property of red hardness, stabi-lizing the hard carbides at high temperatures. It also widens thehardening range of steel and gives deep hardening. Very small quan-tities serve to produce a fine grain and raise the yield point. Thetungsten forms a very hard carbide and an iron tungstite, and thestrength of the steel is also increased, but it is brittle when the tung-sten content is high. When large percentages of tungsten are used insteel, they must be supplemented by other carbide-forming elements.Tungsten steels, except the low-tungsten chromium-tungsten steels,are not suitable for construction; but they are widely used for cuttingtools, because the tungsten forms hard, abrasion-resistant particles inhigh-carbon steels. Tungsten also increases the acid resistance andcorrosion resistance of steels. The steels are difficult to forge and can-not be readily welded when tungsten exceeds 2%. Standard tungsten-chromium alloy steels 72XX contain 1.5 to 2% tungstenand 0.50 to 1 chromium. Many tool steels rely on tungsten as analloying element, and it may range from 0.50 to 2.50% in cold-workand shock-resisting types to 9 to 18 in the hot-work type, and 12 to 20in high-speed steels.

TURPENTINE. Also called in the paint industry oil of turpentine.An oil obtained by steam distillation of the oleoresin which exudeswhen various conifer trees are cut. Longleaf pine and slash pine arethe main sources. It also includes oils obtained by distillation and sol-vent extraction from stumpwood and waste wood. Longleaf sapwoodcontains about 2% oleoresin, heartwood 7 to 10%, and stumpwood25%. Most oleoresin is obtained from the sapwood of living trees, butit is not the sap of the tree. Heartwood resin is obtained only whenthe cut wood is treated with solvents. The oleoresin yields about 20%oil of turpentine and 80 rosin; both together are known as navalstores.

Wood turpentine, called in the paint industry spirits of turpen-tine, is obtained from waste wood, chips, or sawdust by steam extrac-tion or by destructive distillation. Wood turpentine forms more than10% of all American commercial turpentines. Wood turpentine has apeculiar characteristic sawmill odor, and the residue of distillationhas a camphorlike odor different from that of gum turpentine. It dif-fers very little in composition, however, from the true turpentine.Steam-distilled wood turpentine contains about 90% terpenes, ofwhich 80% is alpha pinene and 10% is a mixture of beta pinene and

990 TUNGSTEN STEEL




camphene. Some wood turpentine is produced as a by-product in themanufacture of cellulose. Sulfate turpentine is a by-product in themaking of wood pulp. It varies in composition as the less stable betapinene is affected by the pulping process, and it is used largely inchemical manufacture. By hydrogenation it produces cymene fromwhich dimethyl styrene is made. This material can be copolymer-ized to produce vinyl resins.

Turpentine varies in composition according to the species of pinefrom which it is obtained. It is produced chiefly in the United States,France, and Spain. The turpentine of India comes from the chirpine, Pinus longifolia, of the southern slopes of the Himalayas, alsovalued for lumber, and the khasia pine, P. khasya. The gum of thechir pine is different from U.S. gum, and the turpentine, unless care-fully distilled, is slower-drying and greasy. French and Spanish tur-pentine, or Bordeaux turpentine, is from the maritime pine, P.pinaster, which is the chief source, and from Aleppo pine, P.halepensis, and Corsican pine, P. lavicia. In Portugal, the stonepine, P. pinea, is the source. The French maritime pine is also grownon plantations in Australia. Aleppo pine of Greece was the source ofthe naval stores of the ancients. Venetian turpentine, or Veniceturpentine, is from the Corsican pine or European larch. It producesa harder film than U.S. turpentine. Artificial Venice turpentine ismade by mixing rosin with turpentine. European pines do not give ashigh a yield as U.S. longleaf and slash pines.

American turpentine oil boils at 309°F (154°C), and the specificgravity is 0.860. It is a valuable drying oil for paints and varnishes,owing to its property of rapidly absorbing oxygen from the atmo-sphere and transferring it to the linseed or other drying oil, whichleaves a tough and durable film of paint. Turpentine is also used inthe manufacture of artificial camphor and rubber, and in linoleum,soap, and ink. Gum thus, used in artists’ oil paints, is thickened tur-pentine, although gum thus was originally made from olibanum.Turpentine is often adulterated with other oils of the pine or withpetroleum products, and the various states have laws regulating itsadulteration for paint use.

The pinene in European turpentine is levorotatory while that inthe United States is dextrorotatory. Pinonic acid is acetyl dimethylcyclobutane acetic acid. It is produced by oxidation of the pinene andis a white powder used as a cross-linking agent for making heat-sta-ble plastics.

Terpene alcohol, or methylol pinene, C11H17OH, is produced bycondensing the beta pinene of gum turpentine with formaldehyde.Nopol, of Glidden Co., is terpene alcohol. It has the chemical reac-tions of both a primary alcohol and pinene, and it is used in making

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many chemicals. It is a water-insoluble liquid of specific gravity0.963, boiling at 455°F (235°C). Terpineol is a name for refined ter-pene alcohols used largely for producing essential oils and perfumes.Piccolyte resin is a terpene thermoplastic varnish resin made fromturpentine. The grades have melting points from 50 to 257°F (10 to125°C). Myrcene is a polyolefin with three double bonds, which canbe used as a substitute for butadiene in the manufacture of syntheticrubbers, or can be reacted with maleic anhydride or dibasic acids toform synthetic resins. It is made by isomerizing the beta pinene ofgum turpentine. Camphene is produced by isomerizing the alphapinene of turpentine. Camphor is then produced by oxidation of cam-phene in acid. Camphene was also the name of a lamp oil of the earlynineteenth century made from distilled turpentine and alcohol. Itgave a bright white light, but was explosive. The insecticide known asToxaphene, of Hercules Inc., is made by chlorinating camphene to68% chlorine, or to the empirical formula C10H20Cl8. It is a yellow,waxy powder with a piney odor, melting at 149 to 194°F (65 to 90°C).It is soluble in petroleum solvents.

TURQUOISE. An opaque-blue gemstone with a waxy luster. It is ahydrous phosphate of aluminum and copper oxides. It is found in thewestern United States in streaks in volcanic rocks, but most of theturquoise has come from the Kuh-i-Firouzeh, or turquoise mountain,of Iran, which is a vast deposit of brecciated porphyry, or feldsparigneous rock. The valuable stones are the deep blue. The pale blueand green stones were called Mecca stones because they were sentto Mecca for sale to pilgrims. Bone turquoise, or odontolite, usedfor jewelry, is fossil bone or tooth, colored by a phosphate of iron.

TYPE METAL. Any metal used for making printing type, but the namegenerally refers to lead-antimony-tin alloys. Antimony has the prop-erty of expanding on cooling and thus fills the mold and producessharp, accurate type. The properties required in a type metal are abil-ity to make sharp, uniform castings; strength and hardness; fairly lowmelting point; narrow freezing range to facilitate rapid manufacturein type-making machines; and resistance to drossing. A common typemetal is composed of 9 parts lead to 1 antimony, but many varieties ofother mixtures are also used. The antimony content may be as high as30%, 15 to 20% being frequent. A common monotype metal has 72%lead, 18 antimony, and 10 tin. Larger and softer types are made ofother alloys, sometimes containing bismuth; the hardest small typecontains 3 parts lead to 1 antimony. A low-melting-point, soft-typemetal contains 22% bismuth, 50 lead, and 28 antimony. It will melt atabout 310°F (154°C). Copper, up to 2%, is sometimes added to type

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metal to increase the hardness, but is not ordinarily used in metalsemployed in rapid-acting type machines. Some monotype metal hasabout 18% antimony, 8 tin, and 0.1 copper, but standard linotypemetal for pressure casting has 79% lead, 16 antimony, and 5 tin.Stereotype metal, for sharp casting and hard-wearing qualities, isgiven as 80.0% lead, 13.5 antimony, 6 tin, and 0.5 copper. Intertypemetal has 11 to 14% antimony and 3 to 5 tin. A typical formula forelectrotype metal is 94% lead, 3 tin, and 3 antimony. The Brinellhardness of machine-molded type ranges from 17 to 23, and that ofstereotype metal is up to 30. As constant remelting causes the separa-tion of the tin and lead, and the loss of tin, or impoverishment of themetal, new metal must be constantly added to prevent deterioration ofa standard metal into an inferior alloy. For many years lead-anti-mony-tin alloys have been used as a weld seam filler in auto andtruck bodies. In this application they are commonly referred to asbody solder. Because of advances in printing technology and automanufacturing, use of these lead alloys is steadily declining.

ULTRAHIGH-STRENGTH STEELS. The highest-strength steels avail-able. Arbitrarily, steels with tensile strengths of around 200,000 lb/in2

(1,379 MPa) or higher are included in this category, and more than100 alloy steels can be thus classified. They differ rather widelyamong themselves in composition and/or the way in which the ultra-high strengths are achieved.

Medium-carbon, low-alloy steels were the initial ultrahigh-strength steels, and within this group, a chromium-molybdenumsteel (4130) grade and a chromium-nickel-molybdenum steel(4340) grade were the first developed. These steels have yieldstrengths as high as 240,000 lb/in2 (1,655 MPa) and tensile strengthsapproaching 300,000 lb/in2 (2,069 MPa). They are particularly usefulfor thick sections because they are moderately priced and have deephardenability. Several types of stainless steels are capable ofstrengths above 200,000 lb/in2 (1,379 MPa), including a number ofmartensitic, cold-rolled austenitic, and semiaustenitic grades. Thetypical martensitic grades are types 410, 420, and 431, as well as cer-tain age-hardenable alloys. The cold-rolled austenitic stainlesssteels work-harden rapidly and can achieve 180,000 lb/in2 (1,241MPa) tensile yield strength and 200,000 lb/in2 (1,379 MPa) ultimatestrength. Semiaustenitic stainless steels can be heat-treated foruse at yield strengths as high as 220,000 lb/in2 (1,517 MPa) and ulti-mate strengths of 235,000 lb/in2 (1,620 MPa).

Maraging steels contain 18 to 25% nickel plus substantialamounts of cobalt and molybdenum. Some newer grades containsomewhat less than 10% nickel and between 10 and 14 chromium.

ULTRAHIGH-STRENGTH STEELS 993




Because of the low carbon (0.03% maximum) and nickel content,maraging steels are martensitic in the annealed condition, but arestill readily formed, machined, and welded. By a simple aging treat-ment at about 900°F (482°C), yield strengths as high as 300,000 and350,000 lb/in2 (2,069 and 2,413 MPa) are attainable, depending onspecific composition. In this condition, although ductility is fairly low,the material is still far from being brittle.

Among the strongest of plain carbon sheet steels are the low- andmedium-carbon sheet grades of Inland Steel, called MarTinsite.Made by rapid water quenching after cold rolling, they provide tensileyield strengths to 220,000 lb/in2 (1,517 MPa) but are quite limited inductility.

There are two types of ultrahigh-strength, low-carbon, hardenablesteels. One, a chromium-nickel-molybdenum steel, namedAstralloy, with 0.24% carbon is air-hardened to a yield strength of180,000 lb/in2 (1,241 MPa) in heavy sections when it is normalizedand tempered at 500°F (260°C). The other type is an iron-chromium-molybdenum-cobalt steel and is strengthened by aprecipitation-hardening and aging process to levels up to 245,000lb/in2 (1,689 MPa) in yield strength. High-alloy quenched-and-tem-pered steels are another group that have extrahigh strengths. Theycontain 9% nickel, 4 cobalt, and from 0.20 to 0.30 carbon, and developyield strengths close to 300,000 lb/in2 (2,069 MPa) and ultimatestrengths of 350,000 lb/in2 (2,413 MPa). Another group in this high-alloy category resembles high-speed tool steels, but is modified toeliminate excess carbide, thus considerably improving ductility. Theseso-called matrix steels contain tungsten, molybdenum, chromium,vanadium, cobalt, and about 0.5% carbon. They can be heat-treated toultimate strengths of over 400,000 lb/in2 (2,758 MPa)—the higheststrength presently available in steels, except for heavily cold-worked high-carbon steel strips used for razor blades anddrawn wire for musical instruments, both of which have tensilestrengths as high as 600,000 lb/in2 (4,137 MPa).

Aermet 100, of Carpenter Technology, is a nickel and cobalt steelstrengthened by carbon, columbium, and molybdenum. Originallydeveloped for aerospace applications, it combines high tensile yieldstrength [(250,000 lb/in2 (1,724 MPa)] and fracture toughness[(115,000 lb/in2 in (126 MPa m)]. Uses include aircraft landinggears, racing-car shafts, racing-bicycle frames, mandrel-supportshafts, punch-base supports, and special bolting systems.

URANIUM. An elementary metal, symbol U. It never occurs free innature but is found chiefly as an oxide in the minerals pitchblendeand carnotite where it is associated with radium. The metal has aspecific gravity of 18.68 and atomic weight 238.2. The melting point is

994 URANIUM




about 2071°F (1133°C). It is hard but malleable, resembling nickel incolor, but related to chromium, tungsten, and molybdenum. It is solu-ble in mineral acids.

Uranium has three forms. The alpha phase, or orthorhombic crys-tal, is stable to 1220°F (660°C); the beta, or tetragonal, exists from1220 to 1400°F (660 to 760°C); and the gamma, or body-centeredcubic, is from 1400°F to the melting point. The cast metal has aRockwell B hardness of 80 to 100, work-hardening easily. The metalis alloyed with iron to make ferrouranium, used to impart specialproperties to steel. It increases the elastic limit and the tensilestrength of steels, and is also a more powerful deoxidizer than vana-dium. It will denitrogenize steel and has carbide-forming qualities. Ithas been used in high-speed steels in amounts of 0.05 to 5% toincrease the strength and toughness, but because of its importancefor atomic applications its use in steel is now limited to the by-prod-uct nonradioactive isotope uranium 238. The green salt used inatomic work is uranium tetrafluoride, UF4. Uranium hexafluo-ride, UF6, is a gas used to separate uranium isotopes.

Metallic uranium is used as a cathode in photoelectric tubesresponsive to ultraviolet radiation. Uranium compounds, especiallythe uranium oxides, were used for making glazes in the ceramicindustry and also for paint pigments. It produces a yellowish-green,fluorescent glass, and a beautiful red with yellowish tinge is producedon pottery glazes. Uranium dioxide, UO2, is used in sintered formsas fuel for power reactors. It is chemically stable and has a high melt-ing point at about 5000°F (2760°C), but a low thermal conductivity.For fuel use the particles may be coated with about 0.001 in (0.003cm) of aluminum oxide. This coating is impervious to xenon and otherradioactive isotopes so that only the useful power-providing rays canescape. These are not dangerous at a distance of about 6 in (15 cm),and thus less shielding is needed. For temperatures above 2300°F(1260°C) a coating of pyrolitic graphite is used.

Uranium has isotopes from 234 to 239, and uranium 235, with 92protons and 143 neutrons, is the one valued for atomic work. Thepurified natural metal contains only about one part U235 to about 140parts of U238, and about 100,000 lb (45,360 kg) of uranium fluoride,UF6, must be processed to obtain 1 lb (0.45 kg) of U235F6. Uranium238, after the loss of three alpha particles of total mass 12, changes toradium 226. The lead of old uranium minerals came from Ra226 bythe loss of five alpha particles, and is lead 206, while the lead in tho-rium metals is lead 208. Lead 207 comes from the decay of actinumand exists only in small quantities.

Natural uranium does not normally undergo fission because of thehigh probability of the neutron being captured by the U238 which thenmerely ejects a gamma ray and becomes U239. When natural uranium

URANIUM 995




is not in concentrated form, but is embodied in a matrix of graphite orheavy water, it will sustain a slow chain reaction sufficient to produceheat. In the fission of U235, neutrons are created which maintain thechain reaction and convert U238 to plutonium. About 40 elements ofthe central portion of the periodic table are also produced by the fis-sion, and eventually these products build up to a point where thereaction is no longer self-sustaining. The slow, nonexplosive disinte-gration of the plutonium yields neptunium. Uranium 233 is made byneutron bombardment of thorium. This isotope is fissionable and isused in thermonuclear reactors.

Uranium yellow, also called yellow oxide, is a sodium diu-ranate of composition Na2U2O7 6H2O, obtained by reduction andtreatment of the mineral pitchblende. It is used for yellow and green-ish glazing enamels and for imparting an opalescent yellow to glass,which is green in reflected light. Uranium oxide is an olive-greenpowder of composition U3O8, used as a pigment. Uranium trioxide,UO3, is an orange-yellow powder also used for ceramics and pigments.It is also called uranic oxide. As a pigment in glass, it produces abeautiful greenish-yellow uranium glass. Uranium pentoxide,U2O5, is a black powder, and uranous oxide, UO2, is used in glass togive a fine black color. Sodium uranate, Na2UO4, is a yellow toorange powder used to produce ivory to yellow shades in potteryglazes. The uranium oxide colors give luster and iridescence, butbecause of the application of the metal-to-atom work, the uses in pig-ments and ceramics are now limited.

URANIUM ORES. The chief source of radium and uranium is urani-nite, or pitchblende, a black, massive or granular mineral withpitchlike luster. The mineral is a combination of the oxides of ura-nium, UO2, UO3, and U3O8, together with small amounts of lead, tho-rium, yttrium, cerium, helium, argon, and radium. The process ofseparation of radium is chemically complicated. Uraninite is foundwith the ores of silver and lead in central Europe. In the United Statesit occurs in pegmatite veins, in the mica mines of North Carolina, andin the carnotite of Utah and Colorado. The richest ores come from theCongo and from near Great Bear Lake, Canada. About 370 tons (336metric tons) of Great Bear Lake ore produces 0.002 lb (1 g) of radiumand 7,800 lb (3,538 kg) of uranium, and small amounts of polonium,ionium, silver, and radioactive lead. Numerous minor uranium oresoccur in many areas. A low-grade ore of 0.1% U3O8 can be upgraded toas high as 5% by ion exchange. Black mud from the fjords of Norwaycontains up to 2 oz (0.06 kg) of uranium per long ton (1 metric ton).Tyuyamunite, found in Turkman, averages 1.3% U3O8, with radium,vanadium, and copper. Autunite, or uranite, is a secondary mineral

996 URANIUM ORES




from the decomposition of pitchblende. The composition is approxi-mately P2O5 2UO3 CaO 8H2O. It is produced in Utah, Portugal,and south Australia. Torbernite, or copper uranite,Cu(UO2)2P2O8 12H2O, is a radioactive mineral of specific gravity3.22 to 3.6 and Mohs hardness 2 to 2.5. Sengierite is a copper-ura-nium mineral found in the Congo. It occurs in small green crystals.Casolite is a yellow, earthy lead uranium silicate, 3(PbO UO3 SiO2)4H2O. Pilbarite is a thorium lead uranate. Umohoite, foundin Utah, contains 48% uranium, with molybdenum, hydrogen, andoxygen. The name of the ore is a combination of the symbols of thecontained elements. Uranium is also recovered chemically from phos-phate rock. The phosphate waste rock of Florida contains from 0.1 to0.4% U3O8. Most uranium ores contain less than 0.3% U3O8. Solventmethods of extraction are used.

UREA. Also called carbamide. A colorless to white, crystalline pow-der, NH2 CO NH2, best known for its use in plastics and fertilizers.The chemistry of urea and the carbamates is very complex, and a verygreat variety of related products are produced. Urea is produced bycombining ammonia and carbon dioxide, or from cyanamide, NH2 C N. It is a normal waste product of animal protein metabolism andis the chief nitrogen constituent of urine. It was the first organicchemical ever synthesized commercially. It has a specific gravity of1.323 and a melting point of 275°F (135°C). Industrial grades areavailable either as prills or as a 50% solution from Columbia NitrogenCorp. An ultrapure enzyme grade is produced in small quantities byBethesda Laboratories, and material for electrophoresis by Bio-RadLaboratories.

The formula for urea may be considered as O C(NH2)2, and thus asan amide substitution in carbonic acid, O C(OH)2, an acid whichreally exists only in its compounds. The urea-type plastics are calledamino resins. The carbamates can also be considered as derivingfrom carbamic acid, NH2COOH, an aminoformic acid that like-wise appears only in its compounds. The carbamates have the samestructural formula as the bicarbonates, so that sodium carbamatehas an NH2 group substituted for each OH group of the sodium bicar-bonate. The urethanes, used for plastics and rubber, are alkyl car-bamates made by reacting urea with an alcohol, or by reactingisocyanates with alcohols or carboxyl compounds. They are whitepowders of composition NH2COOC2H5, melting at 122°F (50°C).

Isocyanates are esters of isocyanic acid, H N C O, whichdoes not appear independently. The dibasic diisocyanate of GeneralMills, Inc., is made from a 36-carbon fatty acid. It reacts with com-pounds containing active hydrogen. With modified polyamines it

UREA 997




forms polyurea resins, and with other diisocyanates it forms a widerange of urethanes. Tosyl isocyanate, of Upjohn Co., for producingurethane resins without a catalyst, is toluene sulphonyl isocyanate.The sulphonyl group increases the reactivity.

Methyl isocyanate, CH3NCO, known as MIC, is a colorless liquidwith a specific gravity of 0.9599. It reacts with water. With a flashpoint of less than 20°F (6.6°C), it is flammable and a fire risk. It is astrong irritant and highly toxic. One of its principal uses is as anintermediate in the production of pesticides.

Urea is used with acid phosphates in fertilizers. It contains about45% nitrogen and is one of the most efficient sources of nitrogen. Ureareacted with malonic esters produces malonyl urea, which is thebarbituric acid that forms the basis for the many soporific com-pounds such as luminal, phenobarbital, and amytal. The malonicesters are made from acetic acid, and malonic acid derived from theesters is a solid of composition CH2(COOH)2 which decomposes atabout 320°F (160°C) to yield acetic acid and carbon dioxide.

For plastics manufacture, substitution on the sulfur atom inthiourea is easier than on the oxygen in urea. Thiourea, NH2 CS NH2, also called thiocarbamide, sulfourea, and sulfocarbamide,is a white, crystalline, water-soluble material of bitter taste, with aspecific gravity of 1.405. It is used for making plastics and chemicals.On prolonged heating below its melting point of 360°F (182°C), itchanges to ammonium thiocyanate, or ammonium sulfocyanide,a white, crystalline, water-soluble powder of composition NH4SCN,melting at 302°F (150°C). This material is also used in making plas-tics, as a mordant in dyeing, to produce black nickel coatings, and asa weedkiller. Permafresh, of Warwick Chemical Co., used to controlshrinkage and give wash-and-wear properties to fabrics, is dimethy-lol urea, CO(NHCH2OH)2, which gives clear solutions in warmwater.

Urea-formaldehyde resins are made by condensing urea orthiourea with formaldehyde. They belong to the group known asaminoaldehyde resins made by the interaction of an amine and analdehyde. An initial condensation product is obtained which is solublein water and is used in coatings and adhesives. The final condensa-tion product is insoluble in water and is highly chemical-resistant.Molding is done with heat and pressure. The urea resins are noted fortheir transparency and ability to take translucent colors. Moldedparts with cellulose filler have a specific gravity of about 1.50, tensilestrength from 6,000 to 13,000 lb/in2 (41 to 90 MPa), elongation 15%,compressive strength to 45,000 lb/in2 (310 MPa), dielectric strength to400 V/mil (16 106 V/m), and heat distortion temperature to 280°F(138°C). Rockwell M hardness is about 118. Urea resins are mar-

998 UREA




keted under a wide variety of trade names. The Uformite resins ofRohm & Haas are water-soluble thermosetting resins for adhesivesand sizing. The Urac resins, of American Cyanamid, and the Cascoresins and Cascamite, of Borden Co., are urea-formaldehyde.Borden’s products are available as liquids, 55 to 66% solids, andspray-dried powder grades. They are used as adhesives for plaster-board and plywood and in wet-strength paper. Resi-mat, fromGeorgia-Pacific, is a liquid resin binder for glass-mat roofing andinsulation materials.

URETHANES. Also termed polyurethanes. A group of plastic materi-als based on polyether or polyester resin. The chemistry involved isthe reaction of a diisocyanate with a hydroxyl-terminated polyester orpolyether to form a higher-molecular-weight prepolymer, which inturn is chain-extended by adding difunctional compounds containingactive hydrogens, such as water, glycols, diamines, or amino alcohols.The urethanes are block polymers capable of being formed by a liter-ally indeterminate number of combinations of these compounds. Theurethanes have excellent tensile strength and elongation, good ozoneresistance, and good abrasion resistance. Combinations of hardnessand elasticity unobtainable with other systems are possible in ure-thanes, ranging from Shore A hardness of 15 to 30 (printing rolls, pot-ting compounds) through A 60 to 90 for most industrial or mechanicalgoods applications, to Shore D 70 to 85. Urethanes are fairly resistantto many chemicals such as aliphatic solvents, alcohols, ether, certainfuels, and oils. They are attacked by hot water, polar solvents, andconcentrated acids and bases.

Urethane foams are made by adding a compound that producescarbon dioxide or by reaction of a diisocyanate with a compound con-taining active hydrogen. Foams can be classified somewhat accordingto modulus as flexible, semiflexible or semirigid, and rigid. No sharplines of demarcation have been set on these different classes as thegradation from the flexible to the rigid is continuous. Density of flexi-ble foams ranges from about 1.0 lb/ft3 (16 kg/m3) to 4 to 5 lb/ft3 (64 to80 kg/m3), depending on the end use. Applications of flexible foamsrange from comfort cushioning of all types, e.g., mattresses, pillows,sofa seats, backs and arms, automobile topper pads, and rug under-lay, to clothing interliners for warmth at light weight. Density of rigidurethane foams ranges from about 1.5 to 50 lb/ft3 (24 to 800 kg/m3).

Confor, of E-A-R Specialty Composites, is a line of temperature-sensitive urethane foams for cushioning and padding. Surfaces incontact with body heat, for example, soften and conform to bodyshape while other regions remain stiff and supportive. Unlike fast-recovery foams, recovery is slow. They come in several stiffness

URETHANES 999




grades and colors. TechnoGel, made by TechnoGel in Germany, is apliant polyurethane gel developed by Bayer and used for cushioningseats, beds, and furniture. Isoloss LS foams, of E-A-R, have a fine-cell, high-density structure, featuring high-strength dimensional sta-bility and low compression set. Uses include seals, isolaters, andenergy-absorbing mounts. Conathane UC-38 and UC-39, of Conap,Inc., are liquid, two-component, room-temperature-curing resins forprototype parts. UC-38 has a tensile strength of 5,000 lb/in2 (34 MPa),35% elongation, a Shore D hardness of 75, and a low shrinkage toyield precision parts. UC-39 features a demold time of only 1 h.

Thermoplastic polyurethanes (TPUs) include two basic types:esters and ethers. Esters are tougher, but hydrolyze and degradewhen soaked in water. There also are TPUs based on polycaprolac-tone, which while technically being esters, have better resistance tohydrolysis. TPUs are used when a combination of toughness, flexresistance, weatherability, and low-temperature properties is needed.These materials can be injection-molded, blow-molded, and extrudedas profiles, sheet, and film. Further, TPUs are blended with otherplastic resins, including PVC, ABS, acetal, SAN, and polycarbonate.

Polyol and isocyanate, two highly reactive components of ure-thanes, are used to form flexible bumper fascia for cars by reactioninjection molding (RIM). There are low- and high-modulus unrein-forced grades, as well as glass-reinforced grades for greater rigidity.There are several trade names, including Bayflex, of Miles Inc.There are also grades for what is called structural reaction injectionmolding (SRIM). Polydicyclopentadiene resins can be tailored forRIM or SRIM. Besides milled glass and flaked glass, wollastonite andmica fillers can be used for reinforcement and to improve surface fin-ish. Rimlite, of Miles, refers to the use of lightweight microspheresas fillers.

Urethane elastomers are made with various isocyanates, theprincipal ones being TDI (tolylene diisocyanate) and MDI(4,4´-diphenylmethane diisocyanate) reacting with linear polyolsof the polyester and polyether families. Various chain extenders, suchas glycols, water, diamines, or aminoalcohols, are used in either a pre-polymer or a one-shot type of system to form the long-chain polymer.Recent formulations are more environmentally friendly, containingless solvent, more water, and less aromatic diisocyanates.

Textile fibers of urethane were first made in Germany under thename of Igamide. Flexible urethane fibers, used for flexible gar-ments, are more durable than ordinary rubber fibers or filaments andare 30% lighter in weight. They are resistant to oils and to washingchemicals, and also have the advantage that they are white.Spandex fibers are stretchable fibers produced from a fiber-forming

1000 URETHANES




substance in which a long chain of synthetic molecules is composed ofa segmented polyurethane. Stretch before break of these fibers isfrom 520 to 610%, compared to 760% for rubber. Recovery is not asgood as in rubber. Spandex is white and dyeable. Resistance to chemi-cals is good, but it is degraded by hypochlorides.

There are six basic types of polyurethane coatings, or urethanecoatings, as defined by the American Society for Testing andMaterials Specification D16. Types 1, 2, 3, and 6 have long storagelife and are formulated to cure by oxidation, by reaction with atmo-spheric moisture, or by heat. Types 4 and 5 are catalyst-cured and areused as coatings on leather and rubber and as fast-curing industrialproduct finishes. Urethane coatings have good weathering character-istics as well as high resistance to stains, water, and abrasion. Tolimit emission of volatile organic compounds, there has been a trendto waterborne and high-solids coatings.

A biocompatible, polyurethane-based, shape-memory polymer,developed by Japan’s Mitsubishi Heavy Industries and available inthe United States from Memry Corp., undergoes dramatic changes inhardness, flexibility, elastic modulus, and vapor permeability withsmall temperature changes. It has lower glass transition tempera-tures—standardized at 77°F (25°C), 95°F (35°C), 113°F (45°C), or131°F (55°C)—than former memory polymers and far lower tem-peratures than conventional thermoplastics. Spoon handles, whichcan be heated and reformed to suit the deformed hands of handi-capped persons, is an early use. Potential uses include medicalcatheters (stiff for insertion, flexible once implanted), custom-fittingorthopedic braces and splints, actuator mechanisms, and textile coat-ings whose permeability varies with temperature change.

VALVE ALLOYS. Iron-, nickel-, and cobalt-base alloys are the prin-cipal materials for intake and exhaust valves and valve-seat insertsof reciprocating combustion engines. Requirements include resis-tance to adhesive wear, heat, corrosion, and fatigue. Intake valvesfor light-duty, lower-temperature service are made from plain car-bon steels. Temperatures are generally less than 800°F (425°C) inlight-duty, spark-ignition engines and 930°F (500°C) in heavy-dutyones. Low-alloy martensitic steels, high-alloy martensitic steels,and austenitic steels are used progressively as temperatures andpressures increase. Intake-valve seats are commonly hard-facedwith a seat-facing alloy for the most demanding applications.Exhaust valves require resistance to wear, seat-face burning or gut-tering, fatigue, and creep, the last to prevent head doming or “tulip-ing.” Operating temperatures are generally 1300 to 1400°F (700 to760°C), with spikes as high as 1560°F (850°C). Exhaust valves are

VALVE ALLOYS 1001




typically made of austenitic stainless steels and, for the highestservice temperatures, superalloys.

Valve alloys include 1541H and 1547 carbon steels; 3140, 4140H,5150H, 8645, B16, and GM-8440 low-alloy steels; Sil 1, Sil XB, 422,and SUH 11M martensitic stainless steels; and 21-2N, 21-4N, 21-4N+Cb+W, 23-8N, Gaman H, and 302 HQ austenitic stainlesssteels. Among the superalloys, all nickel-base, are Inconel 751,Nimonic 80A, Pyromet 31V, and Waspaloy. Tensile yield strength at1200°F (650°C) is 8,300 lb/in2 (57 MPa) for 3140, 23,000 lb/in2 (160MPa) for Sil XB, 48,000 lb/in2 (330 MPa) for 21-4N, and 125,000 lb/in2

(860 MPa) for Waspaloy. The last also has a hot hardness of Brinell240. Titanium alloys Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo find limitedspecialty applications. Facing alloys include nickel-base Eatonite,Eatonite 3 and 5, and X-782, and cobalt-base Stellite, 1, 6, 12, andF and Tribaloy T400 and T800. All contain substantial chromiumand molybdenum and/or tungsten.

Insert alloys, also iron-, nickel, or cobalt-base, require hot hard-ness, corrosion resistance, heat resistance, resistance to adhesivewear, and film lubricity to reduce wear. Performance stems largelyfrom the type and distribution of their carbide content. The iron car-bides are the least wear resistant and thermally stable, molybdenumand tungsten M6C carbides are the best in these respects, and thechromium carbides are intermediate. Only cobalt alloys are recom-mended for high-sulfur environments.

Iron-base alloys include M2 tool steel (W70V) and vanadium-freeM2, Sil XB (W90), W93, and W95 (W designations are those ofWinsert, Inc.). The tool steels, which contain M6C carbides, are moreresistant to wear and heat than W90, which contains iron andchromium carbides. Hardness, 38 to 52 Rockwell C at room tempera-ture, falls only to 30 to 34.5 at 800°F (427°C) and to 23.5 to 25 at1000°F (538°C). In contrast, W90 is 35 to 45 at room temperature andfalls to 26.5 and 9, respectively. The tool steels are often used forexhaust applications in gasoline engines and intake applications indiesel engines. W90 is most often used for gasoline and diesel intakeand gasoline exhaust inserts. W10 and W77T6 are Winsert propri-etary compositions intended to replace more costly Stellite andTribaloy cobalt alloys. W10, used for severe sliding-wear applications,has an iron-base laves phase similar to that of Tribaloys but hasgreater hardness at 400 to 1000°F (204 to 538°C), due to forming aprecipitate that improves wear resistance. Applications includeintake and exhaust inserts subject to temperatures as high as 1200°F(649°C) with natural gas and alcohol-base fuels, such as ethanol,methanol, and methane. W77T6, for similar as well as heavy-dutydiesel applications, is a modified tool steel with refined carbides for

1002 VALVE ALLOYS




sliding-wear resistance. Also, it forms a beneficial surface film forintake applications and is especially effective in high-speed opera-tions.

Nickel alloys, most often used for diesel exhaust inserts, includeW230, W240 (GM3550M), W250 (SAE J610B, 13), W260 (J610B, 12),W270, and W280 (Super Eatonite). W240 has a Rockwell C hardnessof 35 to 48 at room temperature, 37 at 800°F, 38.5 at 1000°F, 32 at1200°F, and 18 at 1400°F (760°C). W280 has the greatest Rockwell Chardness: 45 to 55 at room temperature, 44 at 1000°F, 41 at 1200°F,and 30 at 1400°F. W210, a proprietary composition with greater ironcontent, is designed to replace more costly nickel alloys for dieselexhaust inserts. All of these alloys are generally confined to exhaustapplications, performing poorly as intake alloys because, perhaps, ofthe type of film formed at lower temperatures.

As a class, cobalt alloys are generally useful to somewhat highertemperatures (1600°F, 871°C) and also provide sulfidation resistance.They include Stellite 3 (W100), W110 (MIL 15345, Alloy 21), Stellite 6(W120), Stellite 12 (W180), W150, and W170. Stellite 3 has 52%cobalt, 30.5 chromium, and 12.5 tungsten; W150 contains 60 cobalt,28 molybdenum, and 8 chromium. Both alloys have similar RockwellC hardness: 50 to 60 at room temperature and, respectively, 49.5 and51.5 at 800°F, 48.5 and 49.5 at 1000°F, 43 and 42.5 at 1200°F, and 30and 33 at 1400°F. Tribaloy T400 has the advantage of the combinedlubricity and hardness of the laves phase for greater wear resistance.

VANADIUM. An elementary metal, symbol V, widely distributed, butfound in commercial quantities in only a few places, chiefly Peru,Zimbabwe, southwest Africa, and the United States. The commonores of vanadium are carnotite, patronite, roscoelite, and vanadinite.Much of the commercial vanadium comes from Peruvian patroniteand shales. Some Russian vanadium comes from the mineral tyuya-munite, the calcium analog of carnotite. This analog also occurs inAmerican carnotite as a greenish-yellow powder. Titaniferous ores ofSouth Africa also furnish vanadium. But more than 60% of the knownresources are in the United States. Carnotite occurs in Utah andColorado, and the Arizona ore is vanadinite. The most important orein the United States is roscoelite. It is a muscovite mica in whichpart of the aluminum has been replaced by vanadium. It occurs inmicalike scales varying in color from green to brown. It has a specificgravity of 2.9. The ore mined in Colorado contains about 1.5% vana-dium oxide, V2O5, and this oxide is extracted and marketed for mak-ing ferrovanadium and vanadium compounds. The slag from Idahophosphorus workings contains up to 5% vanadium, which is concen-trated to 13% and extracted as vanadium pentoxide. It is recovered

VANADIUM 1003




from petroleum. Venezuelan crude oil, containing 130 ppm vanadium,yields 2,000 lb (907 kg) of vanadium pentoxide per 1 106 gal (3.79 106 L) of oil.

Vanadium is a pale-gray metal with a silvery luster. Its specificgravity is 6.02, and it melts at 3236°F (1780°C). It does not oxidize inair and is not attacked by hydrochloric or dilute sulfuric acid. It dis-solves with a blue color in solutions of nitric acid. It is marketed byVanadium Corp., 99.5% pure, in cast ingots, machined ingots, andbuttons. The as-cast metal has a tensile strength of 54,000 lb/in2 (372MPa), yield strength of 45,000 lb/in2 (310 MPa), and elongation 12%.Annealed sheet has a tensile strength of 78,000 lb/in2 (538 MPa),yield strength 66,000 lb/in2 (455 MPa), and elongation 20%, while thecold-rolled sheet has a tensile strength of 120,000 lb/in2 (827 MPa)with elongation of 2%. Vanadium metal is expensive, but is used forspecial purposes such as for springs of high flexural strength and cor-rosion resistance. The greatest use of vanadium is for alloying.Ferrovanadium, for use in adding to steels, usually contains 30 to40% vanadium, 3 to 6 carbon, and 8 to 15 silicon, with the balanceiron, but may also be had with very low carbon and silicon.Vanadium-boron, for alloying steels, is marketed as a master alloycontaining 40 to 45% vanadium, 8 boron, 5 titanium, 2.5 aluminum,and the balance iron; but the alloy may also be had with no titanium.Van-Ad alloy, for adding vanadium to titanium alloys, contains 75%vanadium and the balance titanium. It comes as fine crystals. Thevanadium-columbium alloys developed by Union Carbide, contain-ing 20 to 50% columbium, have a tensile strength above 100,000 lb/in2

(690 MPa) at 1292°F (700°C), 70,000 lb/in2 (483 MPa) at 1832°F(1000°C), and 40,000 lb/in2 (276 MPa) at 2192°F (1200°C).

Vanadium salts are used to color pottery and glass and as mordantsin dyeing. Red cake, or crystalline vanadium oxide, is a reddish-brown material, containing about 85% vanadium pentox-ide, V2O5, and 9 Na2O, used as a catalyst and for making vanadiumcompounds. Vanadium oxide is also used to produce yellow glass; thepigment known as vanadium-tin yellow is a mixture of vanadiumpentoxide and tin oxide.

VANADIUM STEEL. Vanadium was originally used in steel as acleanser, but is now employed in small amounts, 0.15 to 0.25%, espe-cially with a small quantity of chromium, as an alloying element tomake strong, tough, and hard low-alloy steels. It increases the tensilestrength without lowering the ductility, reduces grain growth, andincreases the fatigue-resisting qualities of steels. Larger amounts areused in high-speed steels and in special steels. Vanadium is a powerfuldeoxidizer in steels, but is too expensive for this purpose alone. Steels

1004 VANADIUM STEEL




with 0.45 to 0.55% carbon and small amounts of vanadium are used forforgings, and cast steels for aircraft parts usually contain vanadium.In tool steels vanadium widens the hardening range, and by the forma-tion of double carbides with chromium makes hard and keen-edged dieand cutter steels. All of these steels are classified as chromium-vana-dium steels. The carbon-vanadium steels for forgings and castings,without chromium, have slightly higher manganese.

Vanadium steels require higher quenching temperatures than ordi-nary steels or nickel steels. SAE 6145 steel, with 0.18% vanadium and1 chromium, has a fine grain structure and is used for gears. It has atensile strength of 116,000 to 292,000 lb/in2 (800 to 2,013 MPa) whenheat-treated, with a Brinell hardness of 248 to 566, depending on thetemperature of drawing, and an elongation of 7 to 26%. In cast vana-dium steels it is usual to have from 0.18 to 0.25% vanadium with 0.35to 0.45 carbon. Such castings have a tensile strength of about 80,000lb/in2 (552 MPa) and an elongation of 22%. A nickel-vanadium caststeel has much higher strength, but high-alloy steels with only smallamounts of vanadium are not usually classified as vanadium steels.

VANILLA BEANS. The seed pods of a climbing plant of the orchid fam-ily of which there are more than 50 known species. It is native toMexico, but now also is grown commercially in Madagascar,Seychelles, Tahiti, Réunion, Mauritius, and tropical America. It isused for the production of the flavor vanilla. The species grown forcommercial vanilla is Vanilla planifolia, a tall climbing herb with yel-low flowers. It grows in humid, tropical climates. The flowers are pol-linated by hand to produce 30 to 40 beans per plant. The green beansare cured immediately in ovens to prevent spoilage after a sweatingprocess. During the curing the glucoside is changed by enzyme actioninto vanillin, which crystallizes on the surface and possesses thecharacteristic odor and flavor. The dark-brown cured pods are put upin small packs in tin containers. Vanillin also occurs naturally inpotato parings and Siam benzoin. Vanilla extract is made bypercolating the chopped bean pods in ethyl alcohol, and then concen-trating the mixture by evaporating the alcohol at a low temperatureto avoid impairing the flavor.

The species V. pompana is more widely distributed, but is not asfragrant. The vanilla grown in Tahiti has an odor of heliotrope whichmust be removed. At least 15 species of vanilla grow in the Amazonand Orinoco valleys. Vanilla was used by the Aztecs for flavoringchocolate. It is now used for the same purpose, and as a flavor for icecream, puddings, cakes, and other foodstuffs.

Vanillin is also produced synthetically from eugenol derived fromclove oil, and from guaiacol obtained by the alkylation of catechol or

VANILLA BEANS 1005




by the destructive distillation of wood. It is also made fromconiferin, C16H22O8 2H2O, a white, crystalline material of meltingpoint 365°F (185°C) obtained from the sapwood of the northern pine.It is produced in Wisconsin from pulp-mill waste liquors by hydratinginto sugars and oxidizing to vanillin. But the synthetic vanillin doesnot give the full, true flavor of vanilla, as a blend of other flavors ispresent in the natural product. The demand for vanilla as a flavor isalways greater than the supply, so that even the grades rated as purevanilla extract may be so adulterated or diluted as to lose the full,rich flavor. Vanillin is used as a chemical intermediate in the produc-tion of pharmaceuticals, such as L-dopa, Trimethaprim, andAldomet.

Ethyl vanillate, C6H3(OH)(OCH)3(COOC2H5), is made fromWisconsin sulfite liquor. It is used in cheese to prevent mold, and as apreservative in tomato and apple juice. Lioxin, of Ontario Paper Co.,is an impure 97% vanillin made from sulfite lignin. It is not suitablefor use as a flavor, but is used as an odor-masking agent, as a bright-ener in zinc-plating baths, as an antifoam agent in lubricating oils,and for making syntans. Veratraldehyde is obtained by methylatingvanillin and is used for brightening metals in the plating industry.Vanitrope, of Shulton, Inc., is a synthetic aromatic with a flavor 15times more powerful than vanillin but with a resinous note resem-bling that of coumarin. It differs from vanillin chemically by havingno aldehyde group, and is a propenyl guaethol related to eugenol.It is used as a vanilla extender. A blend of Vanitrope and vanilla,called Nuvan, is used as a low-cost vanilla flavor. Vanatone andVanarine, of Fritzsche Bros., Inc., are blends of vanillin with aldehy-des and esters to increase the flavor tone.

VAPOR-DEPOSITED COATINGS. Thin, single- or multilayer coatingsapplied to base surfaces by deposition of the coating metal from itsvapor phase. Most metals and even some nonmetals, such as siliconoxide, can be vapor-deposited. Vacuum-evaporated films, or vac-uum-metallized films, of aluminum are most common. They areapplied by vaporizing aluminum in a high vacuum and then allowingit to condense on the object to be coated. Vacuum-metallized films areextremely thin, ranging from 0.002 to 0.1 mil (0.00005 to 0.003 mm).In addition to vacuum evaporation, vapor-deposited films can be pro-duced by ion sputtering, chemical-vapor plating, and a glow-dis-charge process. In ion sputtering, a high voltage applied to a target ofthe coating material in an ionized gas medium causes target atoms(ions) to be dislodged and then to condense as a sputtered coating onthe base material. In chemical-vapor plating, a film is deposited whena metal-bearing gas thermally decomposes on contact with the heated

1006 VAPOR-DEPOSITED COATINGS




surface of the base material. And in the glow-discharge process,applicable only to polymer films, a gas discharge deposits and poly-merizes the plastic film on the base material. In recent years, tita-nium nitride, deposited by chemical vapor deposition or physicalvapor deposition, has been used to markedly increase the wear resis-tance of cutting tools and forming tools made of tool steels.

VARNISH. A solution of a resin in drying oil, which when spread outin a thin film dries and hardens by evaporation of the volatile solvent,or by the oxidation of the oil, or by both. A smooth, glossy coating isleft on the surface. Varnishes do not contain pigments; when mixedwith pigments, they become enamels. The most commonly used resinis ordinary rosin, and the most common drying oils are linseed andtung oils. Spirit varnishes are those in which a volatile liquid, suchas alcohol or ether, is used as a solvent for the resin or oil. They dryby the evaporation of the solvent. Oleoresinous varnishes are thosein which the resin is compounded with an oxidizable oil, such as lin-seed oil. The gums used in varnish, such as copal, dammar, andkauri, produce hardness and gloss to the film, and the fossil resins,such as kauri, give greater hardness and luster to varnishes than dothe natural resins. The oils, such as tung and linseed, make it elasticand durable.

Other important ingredients of varnishes are driers, such as man-ganese oxide, to hasten the action of the drying oil, and thinningagents, or reducers, such as turpentine, naphtha, and benzol.Hydrated lime is added to varnishes to neutralize the acid in theresin, and to clarify and harden the varnish to prevent it from becom-ing sticky in warm weather. Spar varnishes are those made to with-stand weather conditions. Gloss oil is a solution of hardened rosin inbenzene or in turpentine with sometimes a small amount of tung oilto give a tougher film. It gives a high gloss but is not durable. Longvarnishes are those containing 20 to 100 gal (76 to 379 L) of oil to100 lb (45 kg) of resin; a short varnish is one with less oil. The shortvarnishes are hard and glossier, but not as flexible or durable.Ordinarily, quick-drying varnish made with a natural resin is lessdurable than slow-drying; hardness and gloss are not guarantees ofgood varnish.

Varnish was originally only a colorless or nearly colorless coatingmaterial for furniture and fancy wood products to give a smooth, glossysurface for protection and to bring out the texture of the wood, andmarine varnish was a high grade of spar varnish. Any color used wasmerely to accent the original color of the wood or to imitate the color ofanother wood of similar grain. Phenol-formaldehyde varnish isnoted for all-round resistance to weathering under marine conditions.

VARNISH 1007




The finish has a tendency to yellow with age and lose gloss, but thevarnish rarely cracks, peels, or chips. Sometimes called bakelite var-nish because of its resistance to caustic and acid materials, the varnishcan be washed with soap without impairing the finish. Modified phe-nolic varnishes are hard and abrasion-resistant, but are more suscep-tible to weathering. They are suitable for floors, furniture, and toys.Short-oil types may be used for rubbing varnish. Insulating var-nishes were colorless varnishes for protecting drawings, paintings,and other products from moisture, or for electrical insulating. But theterm varnish has come to mean any light-bodied, quick-drying, glossyfinish as distinct from heavily pigmented, glossy enamels. Syntheticvarnishes may now contain synthetic resins in oils, or they may bemade entirely with synthetic resins in solvents. These include bondingand impregnating varnishes, based mainly on alkyd, acrylic, vinyl,epoxy, urethane, amino, and polyester resins. Soybean oil is used in themanufacture of oil-modified alkyd resin varnish, and safflower andsunflower oils in color-retentive urethane varnishes. Electrical var-nishes are likely to be silicone, epoxy, or polyester resins that give gooddielectric strength and adhesion.

VEGETABLE FATS. When specifically used, the term refers particu-larly to semisolid vegetable oils that are used chiefly for food.Vegetable oils and fats usually contain only small quantities of thefat-soluble vitamins A, D, and E, and after refining, they are usuallydevoid of vitamins. Thus, they are a better food in the producingcountries. Climate in which the plant is grown has an effect on thenature of the oils. Warm climates favor the development of oleic acidwhile colder climates favor the less palatable linolenic acid. The low-melting-point oils are more easily assimilated in the body, butwhen these are hydrogenated to a melting point above 113°F (45°C),they become difficult to assimilate. Most of the more edible vegetablefats, as distinct from the more liquid food oils, are tropical products.Suari fat is a hard, white fat with a pleasant taste obtained from thekernels of the seeds of Caryocar brasiliense and other species of tropi-cal America. The kernels yield 60 to 70% fat of a specific gravity of0.989, melting point 86 to 99°F (30 to 37°C), and iodine value 41 to50. Ucuhuba tallow, used in soaps and for candles, is a fat from theseeds of the trees Virola surinamensis and V. sebifera of Brazil. Theseeds yield about 65% fat, but the extraction with petroleum etheralso removes resinous material. The tallow has an iodine value of 10to 15 and a melting point between 109 and 122°F (43 and 50°C).Mahuba fat is a hard, edible fat from the fruit of the treeAcrodicilidium mahuba of Brazil. Gamboge butter, known locally asgurgi and murga, is from the seeds of the fruit of the trees Garcinia

1008 VEGETABLE FATS




morella, G. hanburii, and other species of Sri Lanka and India. Themelting point is 93 to 99°F (34 to 37°C), specific gravity 0.90 to 0.913,and saponification value 196. It is used as a soap and food oil, andlocally as an illuminant and an ointment. From these trees alsocomes the gum resin gamboge used in medicine as a cathartic, andalso used as a brown dyestuff. It is alcohol-soluble.

Sierra Leone butter, also called kanga or lamy, is a pale-yellowfat from the seeds of the fruit of the tree Pentadeama butyracea ofwest Africa. The melting point is about 104°F (40°C), specific gravity0.857 to 0.860, saponification value 186 to 198, and iodine numberaround 60. It is a soap oil. Mafura tallow is a bitter-tasting, heavyfat from the nuts of the tree Trichilia emitica of east Africa. It is usedfor soap, candles, and ointments. The specific gravity is 0.902, melt-ing point about 104°F, and saponification value 201. Shea nut oil,also known as shea butter, Bambuk butter, Galam butter, and byvarious local names as karité, kade, and kedempó, is a fat obtainedfrom the kernels of the fruit of the large tree Bassis butyrospermumof tropical west Africa. The kernels contain 45 to 55% fat, which whenrefined is white, stiffer than lard, with little odor or taste. The melt-ing point is 91 to 108°F (33 to 42°C). It contains oleic and stearic acidsand 3 to 4% lauric acid. It is used in Europe in butter substitutes, asa substitute for cocoa butter, and in candles. Malabar tallow, alsocalled dhupa fat and piney tallow, used in Europe for soap and can-dles and in India for food, is from the kernels of the seed of the ever-green pinne tree, Vateria indica of south India. The tree also yieldswhite dammar or Indian copal. The seeds give about 25% of a greenish-yellow, odorless, and tasteless fat of specific gravity 0.890,melting point 104°F, and saponification value 190. The fat isextracted by grinding the roasted seed, boiling in water, and skim-ming off. It is bleached by exposure.

Vegetable tallow, also called bayberry tallow, capeberry wax,laurel wax, and myrtle wax, used extensively in Europe for soap-making and in the United States for blending in candles and withwaxes, and for polishing leathers, is a waxy fat obtained from the out-side coating of the berries of species of Myrica bushes of America,Europe, and Africa by boiling the berries in water. The berries yield 15to 25% tallow. The species M. cerifera and M. carolinensis grow in theeastern coastal states, and M. mexicana grows in Central America.The melting point of the tallow is 104 to 115°F (40 to 46°C), specificgravity 0.995, and saponification value 205 to 212. The CentralAmerican product contains about 58% myristic acid, 36 palmitic acid,and 1.3 oleic acid. Ocuba wax is a waxy fat, but not chemically a wax,obtained from the seeds of the fruit of the shrub Myristica ocuba ofBrazil. The seeds yield about 20% fat with a specific gravity of 0.920

VEGETABLE FATS 1009




and melting point of 104°F, which is used in candles. The fruit nut issurrounded by a thick skin which yields a water-soluble pink dyeknown as ocuba red.

Mahubarana fat is a pale-yellow, solid oil of melting point 104 to111°F (40 to 44°C) obtained from the kernels of the fruit of trees of thegenus Boldoa. The kernels contain 65% oil, which is used for soapsand candles. Mocaya butter is a fat from the kernels of the nuts ofthe Paraguayan palm, Acrocomia sclerocarpa, of tropical SouthAmerica. The tree resembles a coconut palm, but the nuts grow inbunches. The pulp of the fruit contains 60% of a yellow oil similar topalm oil. The kernels yield 53 to 65% of the mocaya fat, which issofter than palm kernel oil. The specific gravity is 0.865, and saponifi-cation value 240. It has the same uses as palm kernel oil.

VEGETABLE OILS. An important class of oils obtained from plants,used industrially as drying oils, for lubricants, in cutting oils, fordressing leather, and for many other purposes. Many of the oils findwide usage in food products. Large tracts of land are under cultiva-tion in all parts of the world for the production of the seeds and fruitsfrom which the oils are obtained. Linseed, cottonseed, palm, olive,and castor beans are examples of these, and the oils are obtained bycrushing. In some cases the oil-bearing material, copra or soybean,may be dehydrated before crushing, making it simpler to extract theoil, and giving a better residue meal for animal feed. The chief dis-tinction between vegetable oils and fats is a physical one, oils beingfluid at ordinary temperatures. Aceituno oil from the seeds of theCentral American plant Simarouba glauca is a borderline vegetableoil due to its consistency, and it can be easily converted into a veg-etable fat by slight hydrogenation. Vegetable oils can be thickened forvarious uses by oxidation, by blowing air through them, or they canbe solidified by hydrogenation.

In the making of plastics and chemicals from fatty acids derivedfrom vegetable oils, the cost of the oil may be as much as 50% of thefinal cost of the product, and price plays an important part in thechoice of raw material. Oils produced in countries subject to politicaland economic disturbances may have sudden and great price fluctua-tions. Thus, domestic soybean oil may be substituted for castor oil inmaking nylon even though more chemical operations are needed, orthe acids may be synthesized from petroleum hydrocarbons.

Food oils are chosen by their content of essential fatty acids, buttaste is an important factor. Linseed oil is not used for food in theUnited States, although it has high food value and contains bothlinoleic and linolenic acids. Safflower oil, high in linoleic acid, rankshigh as a food oil, only 0.003 lb (1.35 g) of oil being required to provide

1010 VEGETABLE OILS




0.002 lb (1 g) of essential fatty acids. Olive oil, high in oleic acid withonly one double bond, requires 0.031 lb (14.2 g) of oil for 0.002 lb ofessential acid. But olive oil requires less linoleic acid to counteract itseffect than an equivalent amount of a saturated acid with no doublebond. Butter requires the consumption of 0.04 lb (20 g) to obtain0.002 lb of essential acids, while soybean, corn, and cottonseed oils,used in margarine, rank high as food oils.

Considerable oil is extracted from the kernels of the stones or pitsof cherries, apricots, and other fruits as a by-product of the canningand drying of fruits. Cherry kernel oil is from cherry pits whichcontain 30 to 38% oil. The cold-pressed oil is yellow and has a pleas-ant flavor. It is used in salad oils and in cosmetics. The hot-pressed oilis used in soaps. The oil contains 47% oleic acid, 40 linoleic, 4palmitic, 3 stearic, and some arachidic and myristic acids. Apricotkernel oil and almond oil have similar properties and applications.Grapeseed oil is obtained by pressing the by-product grape seedsfrom the wine industry. The seeds contain 10 to 15% oil, valued inEurope as an edible oil, but used in the United States mostly forpaints and soaps. The oil contains about 52% linoleic acid, 32 oleicacid, and palmitic, stearic, and arachidic acids. The hot-pressed oil isdark green and not sweet, but the cold-pressed, refined oil is colorlessand has a nutlike taste. Another name for grapeseed oil is raisinseed oil. Tomato seed oil is from the seeds of the tomato,Lycopersicon esculentum, the seeds being by-products of the manufac-ture of tomato juice and tomato puree, vast quantities of whichare produced in the United States from pulp. The tomato plant is aperennial native to Central and South America, and was grown by theAztecs under the name of tomatl. There are many varieties, and thefruits are true berries. The common red varieties are 2 to 3 in (5 to 8cm) in diameter and contain a large number of seeds in the pulp. Theseeds yield 17% oil by cold pressing, or 33% by solvent extraction. Thecold-pressed oil is a clear liquid of 0.920 specific gravity, with anagreeable odor and bland taste. The iodine number is 113, andsaponification value 192. It is used in salad oils, margarine, soaps,and as a semidrying oil for paints.

VELVET. A closely woven silk fabric with a short pile on one sideformed by carrying the warp threads over wires and then cuttingopen the loops. Velvet is made in a great variety of qualities andweights, and it may have a cotton back in the cheaper grades or bemade in wool. True velvet is all silk; but because of the number ofimitations in other materials, this variety is usually designated assilk velvet. Velvet is dyed in various colors, the depth of colorshown by the pile, giving it an air of richness. Its largest use is in

VELVET 1011




dress goods and hangings, but it is used industrially for upholstery,fancy linings, and trim.

Plush is a name for fabrics woven of cotton, silk, linen, or wool,having a pile deeper than that of velvet. It is used for upholstery.Originally the pile of plush consisted of mohair or worsted yarns, butthere is now no distinction except in the length of the pile. Uphol-stery plush is made in brocade designs by burning the pile withrollers to form a lower background. Plush is also dyed and curled toimitate furs.

Velveteen is an imitation velvet, woven of cotton. In the bestgrades, the pile is of mercerized yarns. Velveteen is woven into twosystems of filling yarns and one system of warp yarns, the pile beingmade with the cut filling yarns instead of the warp yarns, as in vel-vet. It belongs to the class of fustians which also includes moleskinand corduroy. The latter is a sturdy pile fabric with heavy warp rib,dyed in the piece. It is also made in wool. The ribs run lengthwise,while whipcord, a hard-woven worsted fabric, has fine ribs runningdiagonally on the face. Velveteen is used for apparel, linings for jew-elry and silverware boxes, shoe uppers, artificial flowers, and cover-ing material. It is made either plain back or twill back, the plain backhaving a tendency to loosen and drop the pile.

VERMICULITE. A foliated mineral employed in making plasters andboard for heat, cold, and sound insulation, as a filler in caulking com-pounds, and for plastic mortars and refractory concrete. The mineralis an alteration product of biotite and other micas, and is found inColorado, Wyoming, Montana, and the Transvaal. It occurs in crys-talline plates, specific gravity 2.3, and Mohs hardness 1.5, measuringsometimes as much as 9 in (23 cm) across and 6 in (15 cm) in thick-ness. The color is yellowish to brown. Upon calcination at 1750°F(954°C), vermiculite expands at right angles to the cleavage intothreads with a vermicular motion like a mass of small worms; henceits name. The volume increases as much as 16 times, and the colorchanges to a silvery or golden hue. It is ground into pellet form.Plaster made with 60% vermiculite, 30 plaster of paris, and 10asbestos will withstand red heat without disintegrating. Therm-O-Flake brick is made of granules of exfoliated vermiculite bondedwith a chemical. It is lightweight, tough, and withstands tempera-tures to 2000°F (1093°C). The corklike pellets of vermiculite used forinsulating fill in house walls are called mica pellets. Zonolite, of W.R. Grace & Co., is an exfoliated vermiculite. Zonolite Verxite, of thesame company, is a spongy, granular powder form of Verxite, a ther-mally expanded vermiculite. It is used as a blending agent in animalfeeds. A sound-absorbing building tile, called Rockoustile, is made of

1012 VERMICULITE




exfoliated mica. An expanded vermiculite of extremely fine mesh,under the name of Mikolite, is used as an extender in aluminumpaint and in lubricating oils. Exfoliated mica is a name forexpanded vermiculite. Terra-Lite is fluffy, powdered vermiculite forconditioning soils. It holds water, prevents soil crusting, and helps tomaintain soil temperature below the critical 80°F (27°C).

VINYL RESINS. A group of products varying from liquids to hardsolids, made by the polymerization of ethylene derivatives, employedfor finishes, coatings, and molding resins; or it can be made directlyby reacting acetic acid with ethylene and oxygen. In general, the termvinyl designates plastics made by polymerizing vinyl chloride, vinylacetate, or vinylidene chloride, but may include plastics made fromstyrene and other chemicals. The term is generic for compounds of thebasic formula RCH:CR´CR″. The simplest are the polyesters of vinylalcohol, such as vinyl acetate. This resin is lightweight, with a spe-cific gravity of 1.18, and is transparent, but it has poor molding quali-ties and its strength is no more than 5,000 lb/in2 (34 MPa). But thevinyl halides, CH2:CHX, also polymerize readily to form vinyliteresins, which mold well, have tensile strengths to 9,000 lb/in2 (62MPa), high dielectric strength, and high chemical resistance; and awidely useful range of resins is produced by copolymers of vinylacetate and vinyl chloride.

Vinyl alcohol, CH2:CHOH, is a liquid boiling at 95.9°F (35.5°C).Polyvinyl alcohol is a white, odorless, tasteless powder which ondrying from solutions forms a colorless, tough film. The material isused as a thickener for latex, in chewing gum, and for sizes and adhe-sives. It can be compounded with plasticizers and molded or extrudedinto tough and elastic products. Hydrolyzed polyvinyl alcohol hasgreater water resistance and higher adhesion, and its lower residualacetate gives lower foaming. Soluble film, for packaging detergentsand other water-dispersible materials to eliminate the need to openthe package, is a clear polyvinyl alcohol film. Textile fibers are alsomade from polyvinyl alcohol, either water-soluble or insolubilizedwith formaldehyde or another agent. Polyvinyl alcohol textile fiber ishot-drawn by a semimelt process and insolubilized after drawing. Thefiber has a high degree of orientation and crystallinity, giving goodstrength and hot-water resistance.

Vinyl alcohol reacted with an aldehyde and an acid catalyst pro-duces a group of polymers known as vinyl acetal resins, and sepa-rately designated by type names, as polyvinyl butyral and polyvinylformal. The polyvinyl alcohols are called Solvars, and the polyvinylacetates are called Gelvas. The vinyl ethers range from vinylmethyl ether, CH2:CHOCH3, to vinyl ethylhexyl ether, from soft

VINYL RESINS 1013




compounds to hard resins. Vinyl ether is a liquid which polymerizes,or can be reacted with hydroxyl groups to form acetal resins. Alkylvinyl ethers are made by reacting acetylene with an alcohol underpressure, producing methyl vinyl ether, ethyl vinyl ether, orbutyl vinyl ether. They have reactive double bonds which can beused to copolymerize with other vinyls to give a variety of physicalproperties. The polyvinyl formals, Formvars, are used in moldingcompounds, wire coatings, and impregnating compounds. It is one ofthe toughest thermoplastics.

A plastisol is a vinyl resin dissolved in a plasticizer to make apourable liquid without a volatile solvent for casting. The poured liq-uid is solidified by heating. Plastigels are plastisols to which agelling agent has been added to increase viscosity. The polyvinylacetals, Alvars, are used in lacquers, adhesives, and phonographrecords. The transparent polyvinyl butyrals, Butvars, are used asinterlayers in laminated glass. They are made by reacting polyvinylalcohol with butyraldehyde, C3H7CHO. Vinal is a general name forvinyl butyral resin used for laminated glass.

Vinyl acetate is a water-white, mobile liquid with boiling point158°F (70°C), usually shipped with a copper salt to prevent polymer-ization in transit. The composition is CH3:COO:CH:CH2. It may bepolymerized in benzene and marketed in solution, or in water solu-tion for use as an extender for rubber, and for adhesives and coatings.The higher the polymerization of the resin, the higher the softeningpoint of the resin. The formula for polyvinyl acetate resin is givenas (CH2:CHOOCCH3)x. It is a colorless, odorless thermoplastic with aspecific gravity of 1.189, unaffected by water, gasoline, or oils but sol-uble in the lower alcohols, benzene, and chlorinated hydrocarbons.Polyvinyl acetate resins are stable to light, transparent to ultravioletlight, and valued for lacquers and coatings because of their highadhesion, durability, and ease of compounding with gums and resins.Resins of low molecular weight are used for coatings, and those ofhigh molecular weight for molding. Vinyl acetate will copolymerizewith maleic acrylonitrile, or acrylic esters. With ethylene it producesa copolymer latex of superior toughness and abrasion resistance forcoatings.

Vinyl chloride, CH2CHCl, also called ethenyl chloride andchloroethylene, produced by reacting ethylene with oxygen from airand ethylene dichloride, is the basic material for the polyvinyl chlo-ride resins. It is a gas. The plastic was produced originally inGermany under the name of Igelite for cable insulation and asVinnol for tire tubes. The tensile strength of the plastic may varyfrom the flexible resins with about 3,000 lb/in2 (21 MPa) to the rigidresin with a tensile strength to 9,000 lb/in2 (62 MPa) and Shore hard-

1014 VINYL RESINS




ness of 90. The dielectric strength is high, up to 1,300 V/mil (52106

V/m). It is resistant to acids and alkalies. Unplasticized polyvinylchloride is used for rigid chemical-resistant pipe. Polyvinyl chloridesheet, unmodified, may have a tensile strength of 8,200 lb/in2 (57MPa), flexural strength of 12,600 lb/in2 (87 MPa), and a light trans-mission of 78%. Sheet, thermoformed over vinyl foam, is commonlyused for auto dashboard tops. Extrusions are widely used for housesiding and window profiles.

Vinylidene chloride plastics are derived from ethylene and chlo-rine polymerized to produce a thermoplastic with softening point of240 to 280°F (116 to 138°C). The resins are noted for their toughnessand resistance to water and chemicals. The molded resins have a spe-cific gravity of 1.68 to 1.75, tensile strength 4,000 to 7,000 lb/in2 (28 to48 MPa), and flexural strength 15,000 to 17,000 lb/in2 (103 to 117MPa). Saran is the name of a vinylidene chloride plastic of DowChemical Co., extruded in the form of tubes for handling chemicals,brines, and solvents to temperatures as high as 275°F (135°C). It isalso extruded into strands and woven into a box-weave material as asubstitute for rattan for seating. Saran latex, a water dispersion ofthe plastic, is used for coating and impregnating fabrics. For coatingfood-packaging papers, it is waterproof and greaseproof, is odorlessand tasteless, and gives the papers a high gloss. Saran is also pro-duced as a strong, transparent film for packaging. Saran bristles forbrushes are made in diameters from 0.010 to 0.020 in (0.025 to 0.051cm). Vinylidene chloride is also used to line metal pipe for chemicalprocessing equipment.

Vinyl benzoate is an oily liquid of composition CH2:CHOOCC6H5,which can be polymerized to form resins with higher softening pointsthan those of polyvinyl acetate, but are more brittle at low tempera-tures. These resins, copolymerized with vinyl acetate, are used forwater-repellent coatings. Vinyl crotonate, CH2:CHOOCCH:CHCH3,is a liquid of specific gravity 0.9434. Its copolymers are brittle resins,but it is used as a cross-linking agent for other resins to raise the soft-ening point and to increase abrasion resistance. Vinyl formate,CH2:CHOOCH, is a colorless liquid which polymerizes to form clearpolyvinyl formate resins that are harder and more resistant to sol-vents than polyvinyl acetate. The monomer is also copolymerizedwith ethylene monomers to form resins for mixing in specialty rub-bers. Methyl vinyl pyridine, (CH3)(CHCH2)C5H3N, is produced byPhillips Chemical Co. for use in making resins, fibers, and oil-resis-tant rubbers. It is a colorless liquid boiling at 148°F (64.4°C). Theactive methyl groups give condensation reactions, and it will copoly-merize with butadiene, styrene, or acrylonitrile. Polyvinyl car-bazole, under the name of Lucivan, was used in Germany as a mica

VINYL RESINS 1015




substitute for high-frequency insulation. It is a brown resin, softeningat 302°F (150°C).

The possibility of variation in the vinyl resins by change of themonomer, copolymerization, and difference in compounding is sogreat that the term vinyl resin is almost meaningless when usedalone. The resins are marketed under a continuously increasing num-ber of trade names. In general, each resin is designed for specificuses, but not limited to those uses.

Vinylidene fluoride, CH2:CF2, has a high molecular weight, about500,000. It is a hard, white thermoplastic resin with a slippery sur-face, and it has a high resistance to chemicals. It resists temperaturesto 650°F (343°C) and does not become brittle at low temperatures. Itextrudes easily and has been used for wire insulation, gaskets, seals,molded parts, and piping.

VITAMINS. Organic chemical compounds which are vital buildingunits, enzymes, or catalyzing agents in the growth and maintenanceof animal bodies. They are produced by extraction from vegetable oranimal products or are made synthetically and are marketed in solidor extract form for use in foodstuffs and pharmaceuticals. Vitamin A,called carotene because of its abundance in carrots, is an orange-yellow, needle-shaped crystalline substance with a complexmolecular structure having the empirical formula C40H56. It is solublein fats, but poorly soluble in water. Yellow and leafy, green vegetablesare rich sources of carotene-bearing pigments, and carotene accompa-nies the green chlorophyll coloring of all plants. The more intense thegreen or yellow coloring, the greater the carotene content. Lycopene,the red coloring agent of tomatoes, has the same empirical formula ascarotene, and both contain eight isoprene units, but it has a differentstructure. The color is due to large numbers of conjugated doublebonds, and different colors are from different arrangements.Cryptoxanthin, one of the four yellow carotene-carrying pigments,occurs in yellow corn, egg yolk, and green grasses. Animals convertcarotene of green plants to vitamin A which is then obtained commer-cially from the tissues, especially from the liver. Deficiency of vitaminA in the human body causes night blindness, muscular weakness, anddefective tooth structure, but an excess can cause body deformitiesand stillbirth.

Vitamin B is a complex of several vitamins, including vitamin B1and vitamin G. The former cannot be formed in the normal processesof the human body and must be supplied in the diet. Plants manufac-ture and store it in seed. Lack of vitamin B1 causes beriberi, fatigue,stiffness, headache, nervousness, and loss of appetite and, whenchronic, causes enlargement of the heart, polyneuritis, and loss of

1016 VITAMINS




coordination of muscular movements. The crystalline vitamin B1 iscalled thiamine chloride, and in Europe is called aneurin. It iswater-soluble, insoluble in most fats, and is destroyed by heat in thepresence of moisture. In alkaline solutions the destruction is rapid. Itis essential to the health of every living cell. Greater amounts areneeded when lots of starch or sugar foods are eaten in order to pre-vent the formation of pyruvic acid, which produces noxious breath.Pyruvic acid, CH3COCO2H, a liquid boiling at 329°F (165°C), alsocalled glucic acid, pyroacemic acid, and propanone acid, isonion flavor. Onions are root plants of the genus Allium, of whichthere are more than 200 species. They constitute a valuable foodproduct but contain varying amounts of pyruvic acid, from 5.3mol/mil in the yellow Spanish onion to 18.6 in the strongEbenezer onion.

Riboflavin is the accepted name for vitamin B2, or vitamin G.The orange-yellow, needle-shaped crystals have a green fluorescence.Riboflavin, C27H20N4O6, is water-soluble. It is gradually destroyed byexposure to light, and is destroyed by many chemicals, or by hightemperatures in the presence of alkalies. It is present in meats, eggs,barley malt, yeast, milk, green leafy vegetables, and grasses.Deficiency of riboflavin results in ill health, loss of hair, and dermato-sis. Nicotinic acid, or niacin, is the pellagra-preventing member ofthe vitamin B complex. It can be made from the nicotine of the vari-ety of tobacco Nicotiana rustica. Coffee contains some niacin, andmeat extracts are rich in both niacin and riboflavin. Biotin, origi-nally named vitamin H, is also a member of the B group, and has anenzyme action on starches and sugars. It occurs widely in nature as aphytohormone for the growth of organisms and plants. It isextracted from yeast, egg yolk, and liver by adsorbing on carbon.Vitamin B6, C8,H11NO3HCl, called pyridoxine, is required to enablethe human system to assimilate proteins. A deficiency causes nausea,muscular weakness, and anemia. Vitamin B12, or cobalamin, is ahigh-molecular-weight complex containing five-membered nitrogennuclei. It can replace protein as a growth factor.

Vitamin C, C6H8O6, known also as ascorbic acid, or ceritamicacid, is unstable and is easily oxidized, especially in the presence ofalkalies or in iron or copper vessels, so that in foods that have beenlong exposed to the air or overcooked it loses its value. It is thus prob-ably the only vitamin likely to be deficient in the American diet, butthe need is easily satisfied with fresh fruits, tomatoes, and green veg-etables, and it is now added to frozen and canned foods as it also pre-serves the natural color of the products. Isoascorbic acid, orerythorbic acid, has the same composition as ascorbic acid but withthe OH and H reversed on one carbon. It has the same antioxidant

VITAMINS 1017




value, and is a lower-cost chemical, but has no vitamin C activity. It isused in meats to preserve the red color and in canned foods to preventdiscoloring. Mercate 5, of Merck & Co., Inc., is isoascorbic acid forthese purposes, and Mercate 20 is sodium isoascorbate.Cebicure, for curing meats, is ascorbic acid.

The synthetic ascorbic acid is not claimed to be a complete cure forscurvy. The natural vitamin from lemons and limes also containsbioflavins which counteract the skin hemorrhage of scurvy. The juicefrom the acerola plant of Puerto Rico, used for scurvy, is 80 timesricher in vitamin C than orange juice.

Vitamin D regulates the metabolism of calcium and phosphorus inthe human body. Without it the body is subject to rickets, soft bones,or ill-formed bones and teeth. It is also used to counteract the germ oftuberculosis. It is found in fish and fish-liver oils and in some fruits.The vitamin D concentrate of General Mills, Inc., is made by the acti-vation of crystalline ergosterol with low-velocity electrons, in veg-etable oil. Calciferol, or vitamin D2, is a synthetic antiarchiticmarketed in crystalline form or in solution in corn oil. Its meltingpoint is 241°F (116°C). Vitamin D2 is formed in the body from choles-terol by the action of sunlight on the skin. Vitamin E is so widely dis-tributed in foods that the effect is not well known. It is also calledtocopherol as it is a tocopherol acetate. Tofanin, of Winthrop-Stearns, Inc., is vitamin E. Vitamin K5 is very stable. It is used inthe foodstuffs industry instead of sulfur dioxide to control fermenta-tion without affecting flavor, and in medicine to coagulate blood.

Vitamin P is found in capsicum and in lemon peel, and is used as apreventive of rheumatic fever. Although proper quantities of vitaminsare necessary in the human body, overdoses are often toxic and poiso-nous. An excess of vitamin C, for example, causes irritability, vertigo,and vomiting. An excess of vitamin D causes metastatic calcification,or deposition of calcium in the arteries and kidneys, and concentratedvitamin D is classified as a toxic drug. Since metabolism may varywith each person and is also affected by physical condition, vitaminsshould not be taken as supplementary drugs without medical advice.

VULCANIZED FIBER. A wood, paper, or other cellulose fiberboardimpregnated with a gelatinizing medium. It is not vulcanized in thesame sense as rubber is vulcanized. It is made by various processes,and the medium may be sulfuric acid, zinc chloride solution, orcuproammonium solution. It may also be made by impregnating thecellulose fiber with a phenol-furfural resin dissolved in alcohol orother solvent. After dipping in the solution, the fiber is washed toremove excess alcohol, and then dipped in a zinc chloride solutionwhich hydrolyzes it; and it is washed free of the chloride, dried, and

1018 VULCANIZED FIBER




rolled. The original vulcanized fiber, patented in 1899 and calledCellulith, was sulfite wood pulp molded into sheets or formed parts.The modern fiber in the hard grades is a tough, resilient, hornlikematerial in standard gray, red, and black colors. Soft, flexible gradesare made for washers and gaskets. The four major NEMA grades are:electrical insulation, commercial, bone (high-density), and trunk. Thecommercial grade is in thicknesses from 0.005 to 1 in (0.013 to 2.54cm), with lengthwise tensile strength of 7,500 lb/in2 (52 MPa), flex-ural strength of 14,000 lb/in2 (97 MPa), compressive strength of20,000 lb/in2 (138 MPa), and dielectric strength of 250 V/mil (10 106

V/m). Unless impregnated with a synthetic resin, it is not resistant toalkalies. The bone quality is a dense material with a specific gravityof 1.4, capable of being machined. The hard vulcanized fiber ofSpaulding Fibre Co. was made from cotton rags gelatinized in a zincchloride solution and built up in layers. The shear strength is to15,000 lb/in2 (103 MPa), and compressive strength 30,000 lb/in2 (207MPa). Bone fiber is characterized as dense and hard, while trunkfiber is tough and abrasion-resistant. Because of the moderate cost,vulcanized fiber still has many uses, but practically all the materialfor electrical use is now of the insoluble type made with syntheticresin impregnation and having higher dielectric strength. Fishpaper, for electrical use, was originally vulcanized fiber in thick-nesses down to 0.004 in (0.010 cm), but is now likely to be a resinimpregnate. Shoe fiber is vulcanized fiber in leather color used forreinforcement in shoes. It is very resilient, and can be die-cut andnailed. Much of the fiber generally called vulcanized fiber is nowimpregnated with synthetic resins to meet conditions of chemicalresistance, strength, and electrical properties. Vulcanized fiber is pro-duced in the form of sheets, coils, tubes, and rods. Sheets are made inthicknesses of 0.0025 to 2 in (0.0064 to 5 cm) and approximately 48 by80 in (122 by 203 cm) in size. Outside diameters of tubes range from0.1875 to 4.375 in (0.478 to 11 cm). Rods are produced 0.09 to 2 in(0.239 to 5 cm) in diameter.

VULCANIZED OILS. Vegetable oils vulcanized with sulfur and usedfor compounding with rubber for rubber goods, or as a rubber substi-tute. Castor oil, corn oil, rapeseed oil, and soybean oil are used.Vulcanized oil is a white to brown, spongy, odorless cake, or a stickyplastic, with specific gravity of 1.04. The material was invented inFrance in 1847 and was known as factice. Factice cake is solidi-fied, vulcanized oils, cut in slab form. It is an oil modifier of rubber,to add softness and plasticity. It also has some elasticity. Brown fac-tice is made by treating the oil with sulfur chloride at 320 to 392°F(160 to 200°C). The softer grades are made with blown oils and low

VULCANIZED OILS 1019




sulfur. The harder grades contain up to 20% sulfur. White factice ismade from rapeseed oil, which is high in a characteristic acid, crucicacid, by slow addition of sulfur chloride up to 25% sulfur content.Erasing rubbers are rubber compounded with white factice or thefactice alone. Black factice has mineral bitumen added to brownfactice. Neophax is the trade name of Stamford Rubber Supply Co.for brown factice, and Amberex is the name for light-tan-colored fac-tice. Factex of the same company is partly vulcanized oil dispersedin water. It produces a nontacky elastic film. When mixed with rub-ber latex to the extent of 30%, it gives a velvety feel to the vulcanizedproduct and does not decrease the strength greatly. Factice sheet isspecially processed factice made by treating warm oil with sulfur andthen with sulfur chloride. The strength and elasticity are higher.Mineral rubber was a name applied to vulcanized oils mixed withbitumens, especially gilsonite.

WALNUT. A hardwood from the tree Juglans regia, native to Europeand Asia Minor, but now growing in many other places. The wood isfirm, with a fine to coarse, open grain, and a lustrous surface. Thedensity is about 45 lb/ft3 (72l kg/m3). The color is dark brown to black,and it takes a beautiful polish. Walnut has great strength, toughness,and elasticity. It also has great uniformity of texture and does notsplit easily. It is particularly adapted for carving. Walnut is valued asa cabinet wood, for fine furniture, and for gunstocks. The wood fromJ. regia is called English walnut, and the beautifully figured woodfrom Iran is known as Circassian walnut. Black walnut, orAmerican walnut, is from the tree J. nigra, of the eastern UnitedStates. The color is darker, and it has a more uniform color thanEuropean walnut. It is handsomely grained and has the same generalcharacteristics and uses as European walnut. It has a specific gravity,kiln-dried, of 0.56, a shear strength parallel to the grain of 1,000lb/in2 (6.9 MPa), and a compressive strength perpendicular to thegrain of 1,730 lb/in2 (12 MPa). Butternut, from the tree J. cinerea,resembles closely the wood of the black walnut except for its color,which is yellowish gray. The supply of this wood is limited.

East India walnut is the wood of the tree Albizzia lebbek of tropicalAsia and Africa, used for furniture, paneling, and interior decorativework. It is hard, dense, and close-grained, with a density of about 50lb/ft3 (801 kg/m3). The color is dark brown with gray streaks. The logscome as large as 30 in (76 cm) square and 20 ft (6 cm) long. The ship-ments may be mixed with the wood of A. procera, the white siriswood of India. This wood has a brown walnut color, is lustrous, andresembles true walnut more than does the East India walnut. Mahoe,also called blue mahoe and majagua, is the wood of the tree Hibiscus

1020 WALNUT




elatus, of tropical America. It has been used to replace true walnut forgunstocks and in cabinetwork. The wood has a gray-blue color, an aro-matic odor, and is hard with a coarse, open grain. Brazilian walnut,or frejó, from the tree Cordia goeldiana, is a strong, tough, straight-grained wood used for cooperage and cabinetwork.

African walnut, or amonilla, is from the tree Lovoa Klaineana ofNigeria. The wood is brown, and has a fine texture and an interlock-ing grain that shows a striped figure when quartersawed. The densityis about 40 lb/ft3 (641 kg/m3). It is used for flooring, paneling, veneers,and cabinetwork. The Brazilian wood known as imbuia, from thetree Nectandra villosa, is a close match to true walnut and is valuedfor cabinetwork, flooring, and furniture. The heartwood has an oliveto brown color and takes a high polish. There are as many as 50species of Nectandra trees in Brazil, varying widely in characteristics.The canela preta, from the tree N. mollis, is a wood with large,satiny stains on a dark-yellow background. It has a silvery lusterwhen polished, has a spicy scent, and is very durable. It resemblesbleached walnut.

Walnut oil is yellowish oil obtained by pressing the nut kernels ofthe common walnut. It is a good drying oil and is used especially forartists’ paints. The specific gravity is 0.919 to 0.929 and iodine value148. It is soluble in alcohol. The oil from the candlenut is also calledwalnut oil. Walnut-shell flour, made from the refuse shells of thewalnut industry of California, is used as a filler in molded plasticsand in synthetic adhesives to increase bonding strength. It containscellulose with about 28% lignin, 5 furfural, 9 pentosans, 6 methylhydroxylamine, and 2.5 sugars and starch. In colonial times walnutbark was used as a cathartic. It contains a juglone, or nucin, a com-plex naphthoquinone, C10H6O2, a reddish crystalline compound alsocalled lapachol as it occurs also in lapacho, an important hardwoodof Argentina and Paraguay.

WALRUS HIDE. The skin of the walrus, a marine mammal,Odontobaenus rosmarus and O. abesus, native to the north Atlanticand Pacific oceans. The animals sometimes attain a length of 16 ft (5m) and weigh up to 2,000 lb (907 kg), and the hide is obtainable inlarge pieces. They congregate in herds on the icebergs of the north.The skin is tanned and makes a leather with a beautiful naturalgrain. It is also very tough and was formerly much used for coachtraces. It is now employed where a tough and ornamental leather isneeded, but the animals are now scarce and the killing of them is con-trolled by law. Imitation walrus leather is made from speciallytanned and heavy, embossed sheepskins, and is used mostly for bagsand ornamental articles.

WALRUS HIDE 1021




WATER. A nearly transparent liquid of composition H2O. The specificgravity of pure water is taken as 1.0 at 39°F (4°C), and water is usedas the standard for measuring the specific gravity of other liquid andsolid materials. The boiling point is 212°F (100°C), and the freezingpoint is 32°F (0°C). The first essential use of water is for drinking andfor the watering of plants to sustain life; but the largest consumptiveuse is in industrial processing, and a large supply of water is essen-tial for manufacturing.

The per capita intake of water for human drinking is taken as 1 gal(3.8 L) per day, but, because of waste, the amount is larger. The con-sumption of water from the municipal systems of large Americancities exceeds 150 gal (568 L) per capita per day, and that figureincludes some industrial use. The employment of water for hydroelec-tric power is not considered as a consumptive use. About 80% of thesupply in the United States is from surface water, and about 20%from groundwater.

Quality of water is important in many industrial operations.Factories may obtain water from municipal systems, from groundwa-ter pumped from wells, or from surface water from streams. As indus-tries concentrate, it becomes more important to protect water supplyby dams and watersheds, and by preventing the pollution of streamsby the return of unclean water. Typical municipal waters containfrom 30 to 1,000 parts per million (ppm) of dissolved minerals, chieflysilica, iron, calcia, magnesia, potassium, sulfates, chlorides, andnitrates. Organic matter is also present in the water in varyingamounts. So-called pure lake water averages above 150 ppm. Thus,pure water for chemical processing may require ion-exchange purifi-cation after filtering. Water for atomic reactors is thus purified to notmore than 0.08 ppm.

The water molecule is one of the simplest of the chemical combina-tions of the natural elements, but it embraces such a vast complexitythat it can be taken as an example to illustrate the basic principles ofthe combining habits of all the elements. The unit molecule H O Happears to be ovaloid over a wide range of temperatures. The bondingis very strong. With active metallic inclusions in water, the disinte-gration of the molecule may begin at an energy equivalent of about1832°F (1000°C), but complete dissociation into its elements, hydro-gen and oxygen, requires a temperature above 3632°F (2000°C).Water is a very stable oxygen hydride.

The molecule is too minute for measurement of hardness by anyknown methods, but it is deduced to be extremely hard. When astream of water is projected through a tiny orifice at high pressure, itwill cut through a tree as a power saw would. At the energy levels ofthe liquid stage, the molecules are very mobile and roll on each other;

1022 WATER




but when water drips from a faucet or falls as rain, it forms intorounded droplets. The cause is usually given as surface tension, butmay be the electromagnetic attraction of the exposed proton pairs onthe oxygen atoms. When the molecules are lubricated with a chemi-cal, the water flows more easily. This property is used in fire-fightinghose. Polyox FRA, of Union Carbide, is a polymer derivative of eth-ylene oxide used for this purpose. When a 1% solution of the resin isinjected into the line, the stream of water is projected more thantwice the normal distance. Water can also be coated to form drywater of semisolid consistency in the form of droplets which are dryto the touch. This property is utilized in water-based cosmetic creamsby adding silicic acid. Waterglass is a form of soluble sodium silicate.When the cosmetic is applied to the face, silicic acid dehydrolyzes toleave an adherent coating of extremely fine amorphous silica on theskin, and the thin film of released water evaporates quickly to give acool, fresh feel. When heated and pressurized above its critical tem-perature and pressure, water is a supercritical fluid of high dissolvingpower and chemical reactivity, allowing fast oxidation and breakdownof various hazardous wastes.

Lumping and caking of flours and other powders are usually causedby absorption of water moisture from the air, but the addition of aslittle as 0.5% of an anticaking agent such as silicic acid will coatand dry the absorbed moisture and prevent caking. The materialknown as anomalous water has properties similar to those of purewater treated with silicic acid. It forms in dry globules of low mobility,and has a wider temperature range in the liquid state. It is producedby condensing distilled water in vacuum in a small quartz (latticedsilica) tube. The accumulation is extremely slow, requiring 18 h to filla tube 0.010 in (0.025 cm) in diameter. It is also called polywater,though the water molecule does not polymerize in the ordinary mean-ing of the term. The water molecule can also be absorbed within themolecules of many chemicals, both solid and liquid, and such materi-als are called hygroscopic. For example, phosphophenyl methylphosphinic acid has a unit molecular group in the shape of an irregu-lar toroid. With only enough water to fill the spaces in the toroid, theunit is rounded and mobile, and the material becomes a viscous liquidwhich is dissimilar to a water solution of a material. Large propor-tions of water may be encased in the cells and lattices of proteins orother organic materials, making the mass into a solid or semisolid inwhich as much as 97% of the volume is water. This process is used inthe making of puddings such as Jello in which a small amount of edi-ble gelatin encases the water. Water-filled plastics are usually ther-moplastic resins in which 80% or more water is used as a filler. Thewater is stirred into the resin, and the casting sets to a hard, firm

WATER 1023




solid which can be machined, nailed, or screwed. The castings areused for models, ornaments, and such products as lamp stands.

There is no room within the water molecule for the containment ofany other atom or molecule, but the liquid mass may be likened to thearrangement of a great pile of uniformly sized, ovaloid Danish peb-bles, and the mass has comparatively large spaces between andamong the units. All natural waters contain much foreign matterincluding oxygen and other gases from the air, organic material fromplant and animal life, minerals picked up from contact with the earth,and often high proportions of large inorganic molecules such asastrakanite, Na2SO4 MgSO4 4H2O, and carnallite. Groundwater,pumped from deep wells for industrial and municipal uses, was onceconsidered the purest of waters, containing chiefly mineral salts; butin populated areas underground waters are now contaminated withseepage from fertilizers, insecticides, industrial chemicals, andsewage which includes froth-forming detergents. Water in streams, inaddition to the natural minerals and plant-decay matter, now usuallycontains high contents of industrial and agricultural chemicals andsewage, plus biological compounds from the decayed proteins andalbumins of human and animal wastes. Many of these can only beremoved by costly, special ion-exchange methods. Bacteria may beinactivated by the addition of chlorine, but the skatolelike odors mayremain. The content of air in natural water, given in terms of O2, is aminimum of 9 ppm. This contained air is a biological necessity inwater for human consumption and for the maintenance of fish andother marine life. The chemical process of decay of sewage in waterdepletes this oxygen and thus tends to destroy marine life.

Seawater, and water in inland lakes such as the Dead Sea whereevaporation greatly exceeds runoff, contains high amounts of mineralsalts. The variety and percentage content vary in different areas andat different temperatures. The density of seawater at 68°F (20°C)may be 69 lb/ft3 (1,105 kg/m3) compared with about 62 lb/ft3 (993kg/m3) for natural freshwater. About 80 elements have been found inseawater, and it is probable that all of the natural elements occur tosome extent. About 30% of all commercial halite, or common salt, isnow produced from seawater. By ordinary solar evaporation at about80°F (27°C), the proportion of common salt, NaCl, precipitating afterthe calcite and gypsum may be about 12% of the total salts. As muchas 65% of commercial magnesium metal is produced from seawater byprecipitation and reduction of contained magnesium compounds suchas epsomite, kainite, kieserite, bischofite, MgCl2 6H2O, and themagnesium sulfate known as hexahydrite, MgSO4 6H2O. Seawateris a source of pure water via multiflash evaporation or desalinationplants, in areas devoid of freshwater.

1024 WATER




Rain is a source of freshwater, and freshwater is consideredpotable water if it contains less than 500 ppm of dissolved solids.Heavy water is a form of water in which the hydrogen atoms arereplaced by the heavy stable isotope of hydrogen deuterium. Heavywater has a molecular weight of 20.028, melting point of 38.9°F(3.81°C), boiling point of 214.6°F (101.4°C), and a viscosity of 1.107MPa s. At the energy level of solidification the water moleculesarrange themselves in precise order close together, and the frozenwater, or ice, can be split in straight cleavage from a line scratchedon the surface. In the solid assembly of molecules, there is no avail-able space, and the contained impurities of water are thrown out infreezing, except in the dendritic snow molecule. Ice has load-bearingcapacity, and thus the term structural ice. Ice bridges across frozenlakes and rivers in the Arctic have been made of ice reinforced withferry cable and wood. Ice reinforced with random distribution of glassfibers, wood, sawdust, and other materials is called icecrete.Continuous strands of glass yarn add rigidity and, if prestressed,load-carrying capacity.

Ice crystals serve as the blasting medium to clean surfaces of dirtand grease or for paint removal in a system developed at the PennState University Gas Dynamics Laboratory.

WATER REPELLENTS. Chemicals used for treating textiles, leather,and paper such as washable wallpaper, to make them resistant towetting by water. They are different from waterproofing materials inthat they are used where it is not desirable to make the material com-pletely waterproof, but to permit the leather or fabric to “breathe.”Water repellents must not form acids that would destroy the mater-ial, and they must set the dyes rather than cause them to bleed onwashing. There are two basic types: a durable type that resists clean-ing and a renewable type that must be replaced after the fabric isdry-cleaned. Zelan, a pyridinium-resin compound of Du Pont, is rep-resentative of the first type. Quilon, of the same company, is used forpaper, textiles, and glass fabric and forms a strong chemical bond tothe surface of the material by an attachment of the chromium end ofthe molecule through the covalent bond to the negatively charged sur-face. It is a stearotochromic chloride. The second type is usually anemulsion of a mineral salt over which a wax emulsion is placed; thetreatment may be a one-bath process, or it may be by two separatetreatments. Aluminum acetate is one of the most common materialsfor this purpose. Basic aluminum acetate is a white, amorphous pow-der of composition Al(OH)(OOC CH3). It is only slightly soluble inwater but is soluble in mineral acids. Niaproof, of Niacet Corp., is aconcentrated aluminum acetate for waterproofing textiles, and

WATER REPELLENTS 1025




Ramasit and Migasol are similar materials. Zirconium acetate, awhite, crystalline material of composition ZrOH(C2H3O2)3, and itssodium salt are used as water repellents. Zirconyl acetate,ZrO(C2H3O2)2, a light-yellow solution containing 13% ZrO2, is used forboth water repellancy and flame resistance of textile fibers.Intumescent agents are repellent coatings that swell and snuff outfire when they become hot. Latex 744B, of Dow Chemical Co., is arepellent of this type. It is a vinyl water emulsion compounded withpentaerythritol, dicyandiamide, and monosodium phosphate, and isused on textiles, wallboard, and fiber tile.

Silicones have established their value as water-repellent finishesfor a range of natural and synthetic textiles. The silicone polymersmay be added as a solution, an emulsion, or by spraying a fine mist;alternatively, intermediates may be added that either polymerize insitu or attach themselves to the fibers. These techniques result in thepickup of 1 to 3% of silicone resin on the cloth. Commercially,dichloromethylsilane polymer is added as a solution or emulsion toa fabric; this is heated in the presence of a catalyst, such as a zinc saltof an organic acid or an organotin compound, to condense the polymerand form a water-repellent sheath around each fiber. Soluol ChemicalCo.’s Aquagard 170 is a nonionic organopolysiloxane in the form of awhite emulsion; it is cured at low temperatures by its catalystCurade 170, a cationic metallic compound, producing a finish that ishighly durable to dry cleaning. Similar techniques are employed forimparting water repellency to leather. Silicones containing SiHgroups are used for paper treatment. The treated paper has a mea-sure of water repellency and, in addition, some antiadhesive proper-ties. Fluorine-based polymers are also employed for treating fabrics.Gore-Tex, produced by W. L. Gore, is a polytetrafluoroethylene coat-ing on nylon fabric; garments fashioned from this treated nylon areweatherproof and breathable. Scotchgard, from 3M, is a polymercontaining fluoroalkyl groups that is effective for repelling both waterand oil. Scotchban, from the same company, provides water, oil, andgrease repellency to paper. Zepel B, from Du Pont Co., is a fluo-ropolymer dispersion in water that does not promote yellowing or dis-coloration of coated outerware. The Quillon series, also from DuPont, consists of greenish solutions of chrome complexes in iso-propanol that are water-repellent agents for packaging materials,nonwoven fabrics, and adhesive tapes. Vinsol MM from Hercules Inc.is a dark brown, free-flowing powder that is a sodium soap of a blendof Vinsol resin and a fatty acid. It was specially developed for use inmasonry cements.

WATER SOFTENERS. Chemical compounds used for converting solu-ble, scale-forming solids in water into insoluble forms. In the latter

1026 WATER SOFTENERS




condition they are then removed by setting or filtration. The hardnessof water is due chiefly to the presence of carbonates, bicarbonates,and sulfates of calcium and magnesium; but many natural watersalso contain other metal complexes which need special treatment forremoval. Temporary hard waters are those that can be softened byboiling; permanent hard waters are those that require chemicals tochange their condition. Sodium hydroxide is used to precipitate mag-nesium sulfate. Caustic lime is employed to precipitate bicarbonate ofmagnesium, and sodium aluminate is used as an accelerator. Bariumcarbonate may also be used. Prepared water softeners may consist ofmixtures of lime, soda ash, and sodium aluminate, the three actingtogether. Sodium aluminate, Na2Al2O4, is a water-soluble, whitepowder melting at 3002°F (1650°C), which is also used as a textilemordant, for sizing paper, and in making milky glass. ReynoldsMetals Co. produces this material in flake form with iron contentbelow 0.0056% for paints, water softeners, and paper coatings. Alumis used in settling tanks to precipitate mud, and zeolite is used exten-sively for filtering water. The liquids added to the washing water toproduce fluffier textiles are fabric softeners and not water soften-ers. They are usually basic quaternary ammonium compounds suchas distearyl dimethyl ammonium chloride with 16 and 18 carbonatoms, which are cationic, or positively charged. A thin coating isdeposited on the negatively charged fabric, giving a lubricated clothwith a fluffy feel.

Water is also softened and purified with ion-exchange agents,which may be specially prepared synthetic resins. Cation-exchangeagents substitute sodium for calcium and magnesium ions and pro-duce soft waters. When the water is treated with a hydrogen deriva-tive of a resin, the metal cations form acids from the salts. Thecarbonates are converted to carbonic acid which goes off in the air.When it is treated again with a basic resin derivative, or anion-exchange agent, the acids are removed. Water receiving this doubletreatment is equal to distilled water. Salt-cycle anion exchange sub-stitutes chloride ions for other anions in the water, and when com-bined with cation exchange, it produces sodium chloride in the waterin place of other ions.

BiQust, from Purolite Ltd., is an anion-exchange resin developedat Oak Ridge National Laboratories to remove radioactive pertechne-tate from groundwater. It can also be used to treat perchlorate anionin industrial discharge waters. Ion-exchange resins are also beingused to remove metals from metal-plating and electronics waste-waters.

In electrolytic ion exchangers for converting seawater to freshwa-ter, the basic cell is divided into three compartments by two mem-branes, one permeable only to cations and the other only to anions.

WATER SOFTENERS 1027




The sodium ions migrate toward the cathode, and the chlorine ions gotoward the anode, leaving freshwater in the center compartment.Ion-exchange membranes for electrodialysis (salt splitting or sepa-ration), and also used in fuel cells, are theoretically the same as pow-dered exchange resins but with an inorganic binder. Such amembrane resin of the Armour Research Foundation is made by thereaction of zirconyl chloride and phosphoric acid, giving a chain mole-cule of zirconium-oxygen with side chains of dihydrogen phosphate.Zeo-Karb, a sulfonated coat, and Zeo-Rex, a sulfonated phenol-formaldehyde resin, are cation exchangers of Permutit Co., while De-Acidite and Permutit A of the same company are anionexchangers. Amberlite IRA-400, of Rohm & Haas, is a strongly basicalkyl amine which will split neutral salts in the water and alsoremove silica. The German Wofatit P exchanger is a sodium salt of aphenol-formaldehyde resin. Ion-exchange agents are also used forrefining sugar, glycerin, and other products, and for the purificationof acids and the separation of metals. An eluting agent is a solventused to elutriate the resin beds in the separation of metals, that is, toseparate the heavier from the lighter particles, causing a metal ion onthe resin to change place with hydrogen or with an ammonium groupin the elutriant. Zeolites are crystalline aluminosilicates that displaycation-exchange properties. The most common zeolite for softeninguses is zeolite 4A, a sodium aluminosilicate made by Union CarbideCorp. Zeolex is a similar product from J. M. Huber Corp. EZAZeolite A is a white powder from Ethyl Corp. that is employed as areplacement for sodium phosphates in laundry detergents.

WAX. A general name for a variety of substances of animal and veg-etable origin, which are fatty acids in combination with higher alco-hols instead of with glycerin, as in fats and oils. They are usuallyharder than fats, less greasy, and more brittle, but when used alone,they do not mold as well. Chemically, the waxes differ from fats andoils in being composed of high-molecular-weight fatty acids with high-molecular-weight alcohols. The most familiar wax is beeswax from thehoneybee, but commercial beeswax is usually greatly mixed or adul-terated. Another animal wax is spermaceti from the sperm whale.Vegetable waxes include Japan wax, jojoba oil, candelilla, and car-nauba wax. These are sold under the trade name Stralpitz by Strahl& Pitsch, Inc. Mineral waxes include paraffin wax from petroleum,ozokerite, ceresin, and montan wax. The mineral waxes differ from thetrue waxes and are mixtures of saturated hydrocarbons.

The animal and vegetable waxes are not plentiful materials, andare often blended with or replaced by hydrocarbon waxes or waxysynthetic resins. But waxes can be made from common oils and fats

1028 WAX




by splitting off the glycerin and reesterifying selected mixtures of thefatty acids with higher alcohols. Hywax 122 is a self-emulsifiablewax composed of cetyl, myristyl, and stearyl esters derived from ani-mal and vegetable oils. Mazawax and Macol, from MazerChemicals, are fatty alcohol blends with various emulsifiers; they areall-purpose waxes for creams, lotions, hair relaxants, and hair dipila-tory formulations. Opalwax, of Du Pont, is a synthetic wax pro-duced by the hydrogenation of castor oil. It has about the samehardness as carnauba, specific gravity of 0.98, and melting point of187 to 190°F (86 to 88°C), but it lacks the luster of carnauba. It isodorless and has a pearl-white color. It is very resistant to most sol-vents and is used for insulation, coatings, candles, and carbon paper.Acrawax, of Lonza, Inc., is a somewhat similar substitute for car-nauba with higher melting point. Stroba wax, of the same company,is a synthetic wax with a base of stearic acid and lime. The meltingpoint is 217 to 223°F (103 to 106°C). It is used in polishes, insulation,and as a flatting agent. Synthetic wax under the name of Pentawax286 is a true wax in that it is a combination of fatty acids with analcohol. It is made from the long-chain acids of vegetable oils withpentaerythritol. It has a higher melting point than carnauba, 110°F(43°C), but does not form a self-polishing liquid wax as carnaubadoes. Wax R21 is a metal-containing synthetic wax used in liquidfloor waxes, temporary corrosion protection, release agents, and as amelting point booster. Other brands from the same manufacturer,Hoechst Celanese Corp., are Hostalub and Ceridust, which are spe-cialty waxes based on polyolefins, paraffins, chemically modified mon-tan, and micropowders. Sheerwax is made by catalytichydrogenation of vegetable oils. It has the hardness and high meltingpoint of carnauba wax and can be had in white color. Waxes areemployed in polishes, coatings, leather dressings, sizings, waterproof-ing for paper, candles, and varnishes. They are softer and have lowermelting points than resins, are soluble in mineral spirits and in alco-hol, and are insoluble in water.

Some plastics have wax characteristics and may be used in polishesand coatings or for blending with waxes. Polyethylene waxes arelight-colored, odorless solids of low molecular weight, up to about6,000. Mixed in solid waxes to the extent of 50%, and in liquid waxesup to 20%, they add gloss and durability and increase toughness. Inemulsions they add stability. Acumist is a micronized polyethylenewax that is a processing and performance additive for adhesives, coat-ings, color concentrates, cosmetics, inks, lubricants, paints, plastics,and rubber. It can also be constituted from low-molecular-weighthomopolymer, oxidized homopolymer, or as a copolymer. Acumist isfrom Allied-Signal, Inc. Marlex 20, of Phillips Petroleum Co., is a

WAX 1029




methylene polymer used to blend with vegetable or paraffin waxes toincrease the melting point, strength, and hardness. Santowax R, ofMonsanto, is a mixture of terphenyls. It is a light-buff, waxy solid,highly soluble in benzene, and with good resistance to heat, acids,and alkalies. It is used to blend with natural waxes in candles, coat-ings, and insulation. Epolene wax, of Eastman Chemical Products,Inc., is a polyethylene. Waxes are not digestible, and the so-callededible waxes used as water-resistant coatings for cheese, meats, anddried fruits are not waxes, but are modified glycerides. Monocet issuch a material. It is a white, odorless, tasteless, waxy solid meltingat 104°F (40°C) and is an acetylated monoglyceride of fatty acids.

WEAR-RESISTANT STEEL. Many types of steel have wear-resistantproperties, but the term usually refers to high-carbon, high-alloysteels used for dies, tooling, and parts subject to abrasion and forwear-resistant castings. They are generally cast and ground to shape.They are mostly sold under trade names for specific purposes. Theexcess carbon of the steels is in spheroidal form rather than asgraphite. One of the earlier materials of this kind for drawing andforming dies, Adamite, was a chromium-nickel-iron alloy with upto 1.5% chromium, nickel equal to half that of the chromium, andfrom 1.5 to 3.5 carbon with silicon from 0.5 to 2. The Brinell hardnessranges from 185 to 475 as cast, with tensile strengths to 125,000lb/in2 (862 MPa). The softer grades can be machined and then hard-ened, but the hard grades are finished by grinding.

Kinite has about 13% chromium, 1.5 carbon, 1.1 molybdenum, 0.70cobalt, 0.55 silicon, 0.50 manganese, and 0.40 nickel. It is used forblanking dies, forming dies, and cams. Martin steel has 13%chromium, about 1 molybdenum, 0.80 cobalt, 0.35 vanadium, and 1.5carbon. T15 tool steel, for extreme abrasion resistance in cuttingtools, is classified as a super-high-speed steel. It has 13.5% tungsten,4.5 chromium, 5 cobalt, 4.75 vanadium, 0.50 molybdenum, and 1.5carbon. Its great hardness comes from the hard vanadium carbideand the complex tungsten-chromium carbides, and it has full red-hardness. The property of abrasion or wear resistance in steelsgenerally comes from the hard carbides, and is thus inherent withproper heat treatment in many types of steel.

WELDING METALS AND ALLOYS. Materials in the form of rod, wire, orpowder for welding or surfacing, such as hardfacing metals andalloys. Rod and wire are also called electrodes and, if used to fill thejoint, filler metals. American National Standards Institute (ANSI)and/or American Welding Society (AWS) specifications pertain to par-ticular welding processes and electrode material. For example, for

1030 WEAR-RESISTANT STEEL




shielded metal arc welding covered electrodes, ANSI/AWS A5.1 per-tains to carbon steels, A5.5 (low-alloy steels), A5.4 (corrosion-resistantsteels), A5.15 (cast irons), A5.3 (aluminum and aluminum alloys),A5.6 (copper and copper alloys), A5.11 (nickel and nickel alloys), andA5.13 and A5.21 (surfacing). Depending on the type of electrode, thecovering may serve to protect the weld metal from excessive contami-nation and grain growth; establish the electrical characteristics of theelectrode; and improve, directly or by adding alloying elements,mechanical properties of the weld.

Electrodes in each of these specifications are further defined morespecifically. For example, in A5.1, E6010 designates an electrode (E)for 60,000 psi (414 MPa) minimum undiluted weld-metal tensilestrength as welded. According to A5.5, a suffix following the five-unitdesignation indicates the kind of alloy steel, such as carbon-molybde-num, chromium-molybdenum, nickel, or manganese-molybdenumtype. Stainless-steel designations (A5.4) reflect composition of theundiluted weld metal, applicable positioning of the welding operation,and the type of welding current suitable with the electrode.Nonferrous metal and alloy specifications indicate by metal or alloynumerical designation or chemical symbol the metal or alloy.Electrodes for cast iron (A5.15) include nickel, nickel-iron, and nickel-copper alloys and an alloy steel. Phosphor bronze and alu-minum bronze are also used for welding cast iron but the weld is saidto be a braze weld.

Gas tungsten arc welding electrodes are tungsten or tungstenalloys as specified in ANSI/AWS A5.12. Electrode classifications, andcolor identifications applied by band or other means on electrode, areEWP for tungsten (green), EWCe-2 (for tungsten with 2% by weightcerium oxide (orange), EWLa-1 for tungsten with 1% lanthanumoxide (black), EWTh-1 for tungsten with 1% thoria (yellow), EWTh-2for tungsten with 2% thoria (red), EWZr-1 for tungsten with 0.25%zirconia (brown), and EWG for tungsten with rare-earth oxide andnominal content specified by manufacturer. Gas metal arc weldingelectrodes are designated by AWS A5.18 for carbon steels, A5.28 (low-alloy steels), A5.10 (aluminum and aluminum alloys), A5.7 (copperand copper alloys), A5.19 (magnesium and magnesium alloys), A5.14(nickel and nickel alloys), A5.9 (300 and 400 Series stainless steels),and A5.16 (titanium and titanium alloys). Electrode compositions forwelding some aluminum alloys, copper alloys, and steels may differfrom that of the base metals. Electrode classifications within the spec-ifications indicate the electrode alloy or alloy type.

Flux-cored arc welding electrodes generally consist of a hollow steelsheath surrounding a core of fluxing and alloying ingredients. Coreingredients stabilize the arc and/or deoxidize, shield, alloy, and

WELDING METALS AND ALLOYS 1031




improve the properties of the weld metal. Most electrodes are inaccordance with ANSI/AWS A5.20, which classifies 12 for mild steel(EXXT-1 to EXXT-11, plus EXXT-G and EXXT-GS); ANSI/AWS A5.29,which classifies five for low-alloy steels (EXXT1-X, EXXT4-X, EXXT5-X, EXXT-8X, and EXXTX-G); ANSI/AWS A5.22, which classifies fourfor stainless steels (EXXXT-1, -2, -3, and -G); and AWS A5.34, whichclassifies electrodes for nickel alloys. ANSI/AWS A5.25 classifies elec-troslag welding electrodes and ANSI/AWS A5.26 classifies electrogaswelding electrodes. Flux-cored arc welding electrodes are also avail-able for hardfacing, or surfacing, metals for superior heat and corro-sion resistance or to restore worn or damaged parts.

Welding metals and alloys or their forms are known by many tradenames. Intensarc is one for carbon steels. Flexarc rods include arange of stainless steels. Aluminum weld is a 5% silicon aluminumalloy for welding aluminum-silicon alloys. Croloy welding rods, ofBabcock & Wilcox, can weld alloy steels without preheating. They arelow-alloy chromium-molybdenum steels. Chromang, for weldinghigh-alloy steels, is an “18-8” stainless steel modified with 2.5 to 4manganese. An iron-base alloy with 25 nickel, 21 chromium, 7 man-ganese, 5 molybdenum, 1.6 copper, 0.19 nitrogen, 0.015 phosphorusand sulfur, and 0.01 oxygen provides austenitic welds that stay toughat temperatures of 450°F (270°C). Developed at the NationalInstitute of Standards and Technology for welding superconductingmagnets, it offers about twice the fracture toughness of 308 and 316stainless steels.

Chromend 9M, for arc welding hard deposits, contains 8 to 10chromium and 1.5 molybdenum and results in welds of Brinell hard-ness 400. Elkonite is a group of welding alloys made especially forwelding machines. In general, they are sintered tungsten or molybde-num carbides combined with copper or silver and used for spot ratherthan continuous welds. Tungsten electrodes can be pure tungsten,thoriated tungsten, or zirconium tungsten, the latter two being fordirect-current welding. Thoriated tungsten gives high arc stability,and thoria also increases machinability. Zirconium tungsten pro-vides adhesion between the electrode and molten metal for weld uni-formity. Thermit is a mixture of aluminum powder and iron oxide forwelding large sections of iron or steel or for filling large cavities.Thermit welding, developed by Goldschmidt Thermit Co., involvesburning the aluminum to react with the oxide, setting free the iron inmolten form. Cast-iron thermit, for welding cast iron, is thermitwith 3 ferrosilicon and 20 steel. Red thermit is made with red oxide,black thermit with black oxide. Railroad thermit is thermit withadditions of nickel, manganese, and steel. Cast-iron welding elec-trodes, wire, or rod from Washington Alloy Co. include Alloy Nickel

1032 WELDING METALS AND ALLOYS




55 and 99, Alloy EST, and Cascade 17A, 17M, 17T, 18A, 18M, 18T,and RC1. Depending on alloy, weld-metal tensile properties rangefrom ultimate strengths of 50,000 to 84,000 lb/in2 (345 to 579 MPa),yield strengths of 40,000 to 63,000 lb/in2 (276 to 434 MPa), and elon-gations of 3 to 33%. Inco-Weld A, welding wire for stainless steelsand overlays, has 70 nickel, 16 chromium, 8 iron, 2 manganese, 3 tita-nium, and a maximum of 0.07 carbon. Annealed welds have a tensilestrength of 80,000 lb/in2 (552 MPa) and 12% elongation. Nickel weld-ing rod is much used to join cast iron but the operation is brazing, thebase metal not being melted. Colmonoy 23 A is a nickel-alloy weld-ing powder for welding cast iron and for filling blow holes in iron cast-ings by torch application. It contains 2.3 silicon, 1.25 boron, 0.1carbon, 1.5 maximum iron, the balance nickel, and melts at 1950°F(1066°C).

Hardfacing alloys, which increase wear resistance, are alsonumerous. Tungweld rods comprise steel tubes with fine tungsten car-bide particles. Kennemetal KT-200, which has a tungsten carbidecore and steel sheath, gives Rockwell C surface hardness of 63. Thehigh-manganese-steel Amsco welding rods provide Brinell 500 to 700hardnesses. Toolface is a high-speed-steel-rod for facing worn cuttingtools. Superloy, for facing surfaces of extreme hardness, has alloygranules in a soft steel tube. The deposit contains 30 chromium, 8cobalt, 8 molybdenum, 5 tungsten, 0.05 boron, and 0.2 carbon. Tung-alloy, Resisto-Loy and Isorod are other hardfacing rods, Resisto-Loyhaving a nonferrous content. Stoodite is a high-manganese-steel rodand Rockide refers to metal oxide rods for hardfacing.

Weartech alloys, of Weartech International and designated WThardfacing alloys, are a wide range of iron-, nickel-, and cobalt-basehardfacing alloys, many of which are similar to Colmonoy, Stellite,Tribaloy, and other trade-name grades. The iron alloys include Ni-Res alloy for a surface hardness of Brinell 160; Norem-02A,-04A, and -04B alloys, for 32 to 42 Rockwell C hardnesses; and WT-590 and -595 alloys for Rockwell C 58. Except for Ni-Res, which ishigh in nickel (29%), all these alloys are high (22 to 30%) inchromium. The nickel alloys are similar to Colmonoy alloys 4, 5, 6,or 56; Tribaloy 700; Hastelloy C; Ni-60 or Nucalloy 45. They con-tain 11 to 16 chromium and provide Rockwell C hardnesses of 23 to62, depending on the alloy. The cobalt alloys, the most in quantity,include alloy L-605, many Stellite alloy grades, and two Tribaloygrades. Most of these alloys are quite high in chromium content and,depending on alloy, provide 21 to 63 Rockwell C hardnesses. Stellitealloys and Tribaloy alloys are products of Deloro Stellite, Colmonoyalloys are products of Wall Colmonoy, and Norem alloys are productsof the Electric Power Research Institute.

WELDING METALS AND ALLOYS 1033




WETTING AGENTS. Chemicals used in making solutions, emulsions,or compounded mixtures, such as paints, inks, cosmetics, starchpastes, oil emulsions, dentifrices, and detergents, to reduce the sur-face tension and give greater ease of mixing and stability to the solu-tion. In the food industries, chemical wetting agents are added to thesolutions for washing fruits and vegetables to produce a cleaner, bac-teria-free product. Wetting agents are described in general as chemi-cals having a large hydrophilic group associated with a smallerhydrophilic group. Some liquids naturally wet pigments, oils, orwaxes, but others require a proportion of a wetting agent to give mor-dant or wetting properties. Pine oil is a common wetting agent, butmany are complex chemicals. They should be powerful enough not tobe precipitated out of solutions in the form of salts, and they shouldbe free of odor or any characteristic that would affect the solution.Aerosol wetting agents, of American Cyanamid Co., are in the formof liquids, waxy pellets, or free-flowing powders. Aerosol OS is asodium salt of an alkyl naphthalene sulfonic acid. It is a yellowish-brown powder soluble in most organic solvents. This salt was calledNekal in Germany. The Cyanamers are also free-flowing powdersfrom the same company; basically modified polyacrylates, they aresoluble in water and less so in alcohol. The Dresinols of Hercules,Inc., are sodium or ammonium dispersions of modified rosin, with90% of the particles below 39 in (1 m) in size. Polyfon is a sodiumlignosulfonate produced from lignin waste liquor. It is used for dyeand pigment dispersion, oil-well drilling mud, ore flotation, and boilerfeedwater treatment.

WHALE OIL. An oil extracted by boiling and steaming the blubber ofseveral species of whale that are found chiefly in the cold waters ofthe extreme north and south. Whales are mammals and are preda-ceous, living on animal food. The blubber blanket of fat protects thebody, and the tissues and organs also contain deposits of fat. Mostwhale oil is true fat, namely, the glycerides of fatty acids, but thehead contains a waxy fat. In the larger animals the meat and bonesyield more fat than the blubber. Both the whalebone whales and thetoothed whales produce whale oil. The bluehead whales of thesouth, Silbaldus musculus, are the largest and yield the most oil perweight. The whaling industry is under international control, and allo-cations are made on the basis of blue whale units averaging 20 tons(18 metric tons) of oil each. The blue whale is about 25 ft (8 m) long atbirth and reaches 70 ft (21 m) in 2 years. This species often reaches100 ft (30 m) with a weight of about 150 tons (136 metric tons) andwill yield about 27 tons (24 metric tons) of oil. The gray whale, orCalifornia whale, of the northern Pacific, is a small 50-ft (15-m)

1034 WETTING AGENTS




species. The Greenland whale of the north, Balaena mysticetus, andthe finback whale of the south, Balaenoptera physalus, producemuch oil. The beluga, or white whale, Delphinapterus leucas, andthe narwhal, Monodon monoceros, of the north polar seas, produceporpoise oil. Both species of porpoise measure up to 20 ft (6 m) inlength.

Whale oil is sold according to grade, which depends upon its colorand keeping qualities. The latter in turn depends largely upon propercooking at extraction. Grades 0 and 1 are fine, pale-yellow oils, grade2 is amber, grade 3 is pale brown, and grade 4 is the darkest oil.Grade 1 has less than 1% free fatty acids, while grade 4 has from 15to 60% with a strong, fishy odor. The specific gravity is 0.920 to 0.927,saponification value 180 to 197, and iodine value 105 to 135. Whaleoil contains oleic, stearic, palmitic, and other acids in varyingamounts. But whales are now so scarce that the former uses of theoils and meat are restricted, particularly in the United States.

Whale oils of the lower grades were used for quenching baths forheat-treating steels, and in lubricating oils. The best oils are used insoaps and candles, or for preparing textile fibers for spinning, or fortreating leather. In Europe whale oil is favored for making margarinebecause it requires less hydrogen than other oils for hardening, andthe grouping of 16 to 22 carbon atom acids gives the hardened prod-uct greater plasticity over a wider temperature range. Sod oil is oilrecovered from the treatment of leather in which whale or othermarine mammal oil was used. It contains some of the tannins andnitrogenous matter which make it more emulsifiable and more pene-trant than the original oil.

Whale meat was used for food in Japan and in dog food in theUnited States. When it is cured in air, the outside is hard and black,but the inside is soft. In young animals the flesh is pale; in older ani-mals it is dark red. It has a slight fishy flavor, but when cooked withvegetables is almost indistinguishable from beef. It contains 15 to18% proteins. Whale-meat extract is used in bouillon cubes anddehydrated soups. It is 25% weaker than beef extract. Whale liveroil is used in medicine for its high vitamin A content. It also containskitol, which has properties similar to vitamin A but is not absorbedin all animal metabolism. Whalebones are the elastic, hornlikestrips in the upper jaw of the Greenland whale and some otherspecies. The strips are generally from 8 to 10 ft (2 to 3 m) long andnumber up to 600. Those from the bowhead whale of the ArcticOcean are the longest slabs, measuring up to 13 ft (4 m) in length to10 to 12 in (25 to 30 cm) wide at the bottom. Finback whalebone isless than 4 ft (1 m) in length. The humpback whale, Megapteralongimana, of the northern Pacific, is a baleen whale with no teeth

WHALE OIL 1035




and with plates of baleen in the mouth to act as a sieve. It grows to alength of 50 ft (15 m). Whalebone is lightweight, very flexible, elastic,tough, and durable. It consists of a conglomeration of hairy fibers cov-ered with an enamellike fibrous tissue. It is easily split and whensoftened in hot water is easily carved. Whalebone has a variety ofuses in making whips, helmet frames, ribs, and brush fibers. Baleenis a trade name for strips of whalebone used for whips, and for prod-ucts where great flexibility and elasticity are required.

WHEAT. The edible seed grains of an annual grass of the genusTriticum, of which there are many species and thousands of varieties.Wheat was the basic food grain of the early civilizations of the NearEast, and has remained the chief grain of the white races except incold climates where rye grows better. The plains of the United States,Canada, Argentina, Australia, southern Russia, the Danube Valley,and northern India are the great wheat areas.

The types grown commercially are chiefly common wheat anddurum wheat. Common wheat, T. vulgare, is the chief source ofwheat flour. It has a stout head from which the grains can be sepa-rated easily. The hundreds of varieties are divided roughly into hardwheats and soft wheats, and red wheats and white wheats. The hardwheats usually have smaller grains, but are richer in proteins.

Spring wheat is wheat that is sown in the spring and harvested inlate summer. Winter wheat is sown in the fall to develop a root sys-tem before winter and is then harvested in early summer. It is moreresistant and gives a higher yield. Durum wheat, T. durum, has athick head with long beards, and large, hard grains rich in gluten.The plant is hardy and drought-resistant, but the flour is too glute-nous for U.S. bread and is much used for macaroni and in mixtures.Seven classes of wheat are designated in the official grain standardsof the U.S. Department of Agriculture: hard red spring wheat; durumwheat; red durum wheat; hard red winter wheat; soft red winterwheat; white winter wheat; and mixed wheat. Each class permitsmixtures of varieties. The minimum test weight of wheat is requiredto be 60 lb/bu (778 kg/m3).

Most of the wheat production is ground for edible flour. Sincewheat varies with the variety, climate, and soil, uniformity in theflour could formerly be obtained only by blending wheats from differ-ent areas to obtain an average; but uniformity is now obtained by anair-spinning process which separates the milled flour into fractionsaccording to protein-starch ratios and then combining for the flour ofuniform ratio. These are called turbo-flours. Wheat flour is not nor-mally a uniform product even from one area, as it is made up ofstarch granules, fractured endosperm cells, and protein fragments.

1036 WHEAT




Pregelatinized flour is used for canned goods to reduce the timeneeded for dextrinizing. Wheat-flour paste, for textile coatings, ishydroxyethylated flour made by treating wheat flour with ethylene oxide. It requires little cooking to form a starchy product.

Wheat is also used for making beer, and at times is employed forproducing starch and alcohol. Some wheat is used for stock feed, butmost of the wheat for this purpose is of lower and condemned grades.Buckwheat consists of the seed grains of Fagopyrum esculentum, aplant of the same family as the rhubarb and dock. It is native to Asiaand is one of the chief foods in Russia, but is used only in mixed floursin the United States. The flour is more starchy and has less proteinthan wheat. It is also darker in color and has a different flavor.

WHETSTONE. Stones of regular fine grains composed largely of chal-cedony silica, often with minute garnet and rutile crystals. They areused as fine abrasive stones for the final sharpening of edge tools.Whetstones are also sometimes selected, fine sandstones from thegrindstone quarries. The chocolate whetstone from NewHampshire is mica schist. The finest whetstones are called oilstones.A fine-grained honestone, known as coticule, comes from Belgiumand is used for sharpening fine-edged tools. It is compact, yellow incolor, and contains minute crystals of yellow manganese garnet, withalso potash mica and tourmaline. Coticule is often cut double withblue-gray phyllite rock adhering to and supporting it. Scythestonesare made from Ohio and Indiana sandstones and from the schist ofVermont. Rubbing stones are fine-grained Indiana sandstones.

WHISKERS. Very fine, single-crystal fibers that range from 118 to394 in (3 to 10 m) in diameter and have length-to-diameter ratiosof 50 to 10,000. Since they are single crystals, their strengthsapproach the calculated theoretical strengths of the materials.Alumina whiskers, which have received the most attention, havetensile strengths up to 3 106 lb/in2 (20,700 MPa) and a modulus ofelasticity of 62 106 lb/in2 (427,000 MPa). Other whisker materialsare silicon carbide, silicon nitride, magnesia, boron carbide,and beryllia.

WHITE BRASS. A bearing metal which is actually outside of the rangeof the brasses, bronzes, or babbitt metals. It is used in various grades,the specification adopted by SAE being tin, 65%; zinc, 28 to 30; andcopper, 3 to 6. It is used for automobile bearings and is close-grained,hard, and tough. It also casts well. A different alloy is known underthe name of white brass in the cheap jewelry and novelty trade. It hasno tin, small proportions of copper, and the remainder zinc. It is a

WHITE BRASS 1037




high-zinc brass and varies in color from silvery white to yellow,depending upon the copper content. An old alloy formerly used forcasting buttons, known as Birmingham platina, or platina, con-tained 75% zinc and 25 copper. It had a white color but was very brit-tle. A yellowish metal known as bath metal, once widely used forcasting buttons, candlesticks, and other articles, was a brass contain-ing 55% copper and 45 zinc. White nickel brass is a grade of nickelsilver. The white brass used for castings where a white color isdesired may contain up to 30% nickel. The 60:20:20 alloy is used forwhite plaque castings for buildings. The high-nickel brasses do notcast well unless they also contain lead. Those with 15 to 20% nickeland 2 lead are used for casting hardware and valves. White nickelalloy is a copper-nickel alloy containing some aluminum. White cop-per is a name sometimes used for copper-nickel alloy or nickel brass.Nickel brasses known as German silver are copper-nickel-zinc whitealloys used as a base metal for plated silverware, for springs and con-tacts in electrical equipment, and for corrosion-resistant parts. Thealloys are graded according to the nickel content. Extra-white metal,the highest grade, contains 50% copper, 30 nickel, and 20 zinc. Thelower grade, called fifths, for plated goods, has a yellowish color. Itcontains 57% copper, 7 nickel, and 36 zinc. All of the early Germansilvers contained up to 2% iron, which increased the strength, hard-ness, and whiteness, but is not desirable in the alloys used for electri-cal work. Some of the early English alloys also contained up to 2% tin,but tin embrittles alloys. The Federal Trade Commission prohibitsthe use of the term German silver in the marketing of silver-platedware, but the name still persists in other industries.

WHITE GOLD. The name of a class of jewelers’ white alloys used assubstitutes for platinum. The name gives no idea of the relative valueof the different grades, which vary widely. Gold and platinum may bealloyed together to make a white gold, but the usual alloys consist of20 to 50% nickel, with the balance gold. Nickel and zinc with goldmay also be used for white golds. The best commercial grades of whitegold are made by melting the gold with a white alloy prepared for thispurpose. This alloy contains nickel, silver, palladium, and zinc. The14-karat white gold contains 14 parts pure gold and 10 white alloy. Asuperior class of white gold is made of 90% gold and 10 palladium.High-strength white gold contains copper, nickel, and zinc with thegold. Such an alloy, containing 37.5% gold, 28 copper, 17.5 nickel, and17 zinc, when aged by heat treatment, has a tensile strength of about100,000 lb/in2 (690 MPa) and an elongation of 35%. It is used for mak-ing jewelry; has a fine, white color; and is easily worked into intricateshapes. Two nickel-free white gold alloys, developed by Handy and

1038 WHITE GOLD




Harmon, contain about 51% silver, 5 palladium, and either 2 zinc or 2germanium. They were developed because some people are allergic tonickel leaching from 10-karat white gold alloys. White-gold solderis made in many grades containing up to 12% nickel, up to 15 zinc,with usually also copper and silver, and from 30 to 80 gold. The melt-ing points of eight grades range from 1283 to 1553°F (695 to 845°C).

WHITE METALS. Although a great variety of combinations can bemade with numerous metals to produce white or silvery alloys, thename usually refers to the lead-antimony-tin alloys employed formachine bearings, packings, and linings; to the low-melting-pointalloys used for toys, ornaments, and fusible metals; and to the typemetals. Slush castings, for ornamental articles and hollow parts, aremade in a wide variety of soft white alloys, usually varying propor-tions of lead, tin, zinc, and antimony, depending on cost and the accu-racy and finish desired. These castings are made by pouring themolten metal into a metal mold without a core, and immediatelypouring the metal out, so that a thin shell of the alloy solidifiesagainst the metal of the mold and forms a hollow product. A numberof white metals are specified by the ASTM for bearing use. These varyin a wide range from 2 to 91% tin, 4.5 to 15 antimony, up to 90 lead,and up to 8 copper. The alloy containing 75% tin, 12 antimony, 10lead, and 3 copper melts at 363°F (184°C), is poured at about 707°F(375°C), and has an ultimate compressive strength of 16,150 lb/in2

(111 MPa) and a Brinell hardness of 24. The alloy containing 10% tin,15 antimony, and 75 lead melts at 464°F (240°C) and has a compres-sive strength of 15,650 lb/in2 (108 MPa) and a Brinell hardness of 22.The first of these two alloys contains copper-tin crystals; the secondcontains tin-antimony crystals. A white bearing metal produced underthe name of Asarcoloy is composed of cadmium with 1.3% nickel. Itcontains NiCd7 crystals, is harder and has higher compressivestrength than babbitt, and has a low coefficient of friction. It has amelting point of 604°F (317°C). SAE Alloy 18 is such a cadmium-nickel alloy with also small amounts of silver, copper, tin, and zinc.A bismuth-lead alloy containing 58% bismuth and 42 lead melts at254°F (123.5°C). It casts to exact size without shrinkage or expansionand is used for master patterns and for sealing.

Various high-tin or reverse bronzes have been used as corrosion-resistant metals, especially before the advent of the chromium,nickel, and aluminum alloys for this purpose. Trabuk was a corro-sion-resistant, high-tin bronze with about 5% nickel. Fahry’s alloywas a reverse bronze containing 90% tin and 10 copper, used as abearing metal, and the Jacoby metal used for machine parts had85% tin, 10 antimony, and 5 copper. The scarcity and high cost of tin

WHITE METALS 1039




have made these alloys obsolete. The bearing alloy known in Englandas motor bronze is a babbitt with about twice the copper of a stan-dard babbitt. One analysis gives tin, 84%; antimony, 7.5; copper, 7.5;and bismuth 1. An old alloy, used in India for utensils and known asbidery metal, contained 31 parts zinc, 1 lead, and 2 copper, fluxedwith resins. It was finished with a velvety-black color by treatingwith a solution of copper sulfate. A white metal sheet now muchused for making stamped and formed parts for costume jewelry andelectronic parts is zinc with up to 1.5% copper and up to 0.5 titanium.The titanium with the copper prevents coarse-grain formation, rais-ing the recrystallization temperature. The alloy weighs 2% less thancopper, and it plates and solders easily. Zilloy-20 is pure zinc with nomore than 1% of other elements. In rolled strip it has a tensilestrength up to 27,000 lb/in2 (186 MPa) and elongation of 35%.

WILLOW. The wood of the trees Salix coerulea and S. alba, native toEurope, but grown in many other places. It is best known as a mater-ial for cricket bats made in England. The American willows areknown as black willow, from the tree S. nigra, and western blackwillow, from the tree S. lasiandra. The wood is also employed formaking artificial limbs and for articles where toughness and non-shrinking qualities are valued. The wood is brownish yellow; has afine, open grain; and has a density of about 30 lb/ft3 (481 kg/m3). It isof the approximate hardness of cherry and birch. Japanese willowis from the tree S. urbaniana. It has a closer and finer texture and abrowner color. Black willow has a maximum crushing strength paral-lel to the grain of about 1,500 lb/in2 (10 MPa). Salicin, also calledsalicoside and saligenin, is a glucoside extracted from severalspecies of willow bark of England and also from the American aspen.It is a colorless, crystalline material of composition (OH)4C6H7 OO C6H4CH2OH, decomposing at 394°F (201°C) and soluble in water andin alcohol. It is used in medicine as an antipyretic and tonic, and as areagent for nitric acid. It hydrolyzes to glucose and salicyl alcohol,and the latter is oxidized to salicylic acid, C6H4(OH)COOH.Aspirin, acetyl salicylic acid, is used as an antipyretic and anal-gesic.

WIRE CLOTH. Stiff fabrics made of fine wire woven with plain, looseweave, used for screens to protect windows, for guards, and for sievesand filters. Steel and iron wire may be used—plain, painted, galva-nized, or rustproofed—or various nonferrous metal wires areemployed. It is usually put up in rolls in widths from 18 to 48 in (46to 122 cm). Screen cloth is usually 12, 14, 16, and 18 mesh, but wirecloth in copper, brass, or Monel metal is made regularly in meshes

1040 WILLOW




from 4 to 100. The size of wire is usually from 0.009 to 0.065 in (0.023to 0.165 cm) in diameter. Wire cloth for fine filtering is made in veryfine meshes. Mesh indicates the number of openings per inch and hasno reference to the diameter of wire. A 200-mesh cloth has 200 open-ings each way on a square inch, or 40,000 openings per square inch(6.4 cm2). Wire cloth as fine as 400 mesh, or having 160,000 openingsper square inch (6.4 cm2), is made by wedge-shaped weaving,although 250 wires of the size of 0.004 in (0.010 cm) when placed par-allel and in contact will fill the space of 1 in (2.5 cm). Very fine-meshwire cloth must be woven at an angle since the globular nature ofmost liquids will not permit passage of the liquid through microscopicsquare openings. One wire screen cloth, for filtering and screening,has elongated openings. One way the 0.0055-in (0.0140-cm) wirecount is 200 per inch (2.5 cm), while the other way the 0.007-in(0.018-cm) warp wire count is 40 per inch (2.5 cm).

Wire fabrics for reentry parachutes are made of heat-resistantnickel-chromium alloys, and the wire is not larger than 0.005 in(0.013 cm) in diameter to give flexibility to the cloth. Wire fabrics forion engines to operate in cesium vapor at temperatures to 2400°F(1316°C) are made with tantalum, molybdenum, or tungsten wire,0.003 to 0.006 in (0.008 to 0.015 cm) in diameter, with a twill weave.Meshes to a fineness of 350 by 2,300 can be obtained. Porosity unifor-mity is controlled by pressure calendaring of the woven cloth, but forextremely fine meshes in wire cloth it is difficult to obtain the unifor-mity that can be obtained with porous sintered metals.

Where accuracy of sizing is not important, as in gravel or orescreening, wire fabric is made with oblong or rectangular openingsinstead of squares to give faster screening. High-manganese steelwire is used for rock screens. For window screening in tropical cli-mates or in corrosive atmospheres, plastic filaments are sometimessubstituted for the standard copper or steel wire. Lumite screencloth is woven of vinylidene chloride monofilament 0.015 in (0.038cm) in diameter in 18 and 20 mesh. The impact strength of the plasticcloth is higher than that of metal wire cloth, but it cannot be used forscreening very hot materials. Lektromesh is copper or nickel screencloth of 40 to 200 mesh made in one piece by electrodeposition. It canbe drawn or formed more readily than wire screen, and circular orother shapes can be made with an integral selvage edge.

WIRE GLASS. A sheet glass used in building construction for windows,doors, floors, and skylights, having woven wire mesh embedded in thecenter of the plate. It does not splinter or fly apart as common glasswhen subjected to fire or shock, and it has higher strength than com-mon glass. It is made in standard thicknesses from 0.125 to 0.375 in

WIRE GLASS 1041




(0.318 to 0.953 cm) and in plates 60 by 110 in (1.5 by 2.8 m) and 61 by140 in (1.5 by 3.6 m). Underwriters’ specifications call for a minimumthickness of 0.25 in (0.635 cm). Wire glass is made with plain, rough,or polished surfaces, or with ribbed or cobweb surface on one side fordiffusing the light and for decorative purposes. It is also obtainable incorrugated sheets, usually 27.75 in (70.5 cm) wide. Wire glass 0.25 in(0.635 cm) thick weighs 2.25 lb/ft2 (11 kg/m2). Plastic-coated wire meshmay be used to replace wire glass for hothouses or skylights where lessweight and fuller penetration of light rays are desired. Cel-O-Glass, ofDu Pont, is a plastic-coated wire mesh in sheet form.

WOLLASTON WIRE. Any wire made by the Wollaston process of fine-wire drawing. It consists of inserting a length of bare drawn wire intoa close-fitting tube of another metal, the tube and core then beingtreated as a single rod and drawn through dies down to the requiredsize. The outside jacket of metal is then dissolved away by an acidthat does not affect the core metal. Platinum wire as fine as 0.00005in (0.00013 cm) in diameter is made commercially by this method,and gold wire as fine as 0.00001 in (0.00002 cm) in diameter is alsodrawn. Wires of this fineness are employed only in instruments. Theyare marketed as composite wires, the user dissolving off the jacket.Taylor process wire is a very fine wire made by the process ofdrawing in a glass tube. The process is used chiefly for obtaining finewire from a material lacking ductility, such as antimony, or extremelyfine wire from a ductile metal. The procedure is to melt the metal oralloy into a glass or quartz tube, and then draw down this tube withits contained material. Wire as fine as 0.00004 in (0.00012 cm) indiameter is made, but only in short lengths.

WOOD. A general name applied to the cut material derived fromtrees. A tree, as distinguished from a bush, is designated by the U.S.Forest Service as a woody plant with a single erect stem 3 in (7.6 cm)or more in diameter at 4.5 ft (1.4 m) above the ground, and at least 12ft (3.7 m) high. But this definition is merely empirical since in thecold climate of northern Canada, perfect, full-grown trees 10 to 15years old may be only 6 in (15 cm) high. Timber, in general, refers tostanding trees, while lumber is the sawed wood used for constructionpurposes. In construction work the word timber is often applied tolarge pieces of lumber used as beams.

Wood is an organic chemical compound composed of approximately49% carbon, 44 oxygen, 6 hydrogen, and 1 ash. It is largely celluloseand lignin. The wood of white pine is about 50% cellulose, 25 lignin,and the remainder sugars, resin, acetic acid, and other materials.Wood is produced in most trees by a progressive growth from the out-

1042 WOLLASTON WIRE




side. In the spring, when sap flows rapidly, a rapid formation of largecells takes place, followed by a slower growth of hard and close cells insummer. In some woods, such as oak, there is a considerable differencein quality and appearance between the spring and summer woods. Insome long-lived trees, such as Douglas fir, there is a decrease instrength between the outside wood with narrow rings and the wide-ringed wood of the interior. Heartwood is the dark center of the treewhich has become set, and through which the sap has ceased to flow.Sapwood is the outer, live wood of the tree; unless treated, it has lowdecay resistance. The grain of sawed lumber results from sawingacross the annual growth rings, varied to produce different grains.

Wood is seasoned either by exposing it to the air to dry or by kilndrying. The former method is considered to give superior quality, butit requires more time, is expensive, and is indefinite. Numerous testsmade at the U.S. Forest Products Laboratory did not reveal any supe-riority in air-dried wood when kiln drying was well done. Solvent sea-soning is a rapid process consisting of circulating a hot solventthrough the wood in a closed chamber. California redwood, when sea-soned with acetone at 130°F (54°C), yields tannin and some otherchemicals as by-products. Seasoned wood, when dry, is alwaysstronger than unseasoned wood. Tank woods are selected for resis-tance to the liquids to be contained. Tanks for vinegar and foodstuffscontaining vinegar, such as pickles, are of white oak, cypress, or west-ern red cedar. Beer tanks are of white oak or cypress. Tanks for agingwine are of redwood, oak, or fir. The traditional violin woods arespruce and curly maple, although sugar maple is also used.

The term log designates the tree trunk with the branches removed.Balk is a roughly squared log; plank is a piece cut to rectangular sec-tion 11 in (28 cm) wide; deal is a piece 9 in (23 cm) wide; and battenis a piece 7 in (18 cm) wide. Board is a thin piece of any width lessthan 2 in (5 cm). Flitch is half a balk, cut in two lengthwise.Scantling is a piece sawed on all sides. Shakes are longitudinalsplits or cracks in the wood due to shrinkage or decay.

All woods are divided into two major classes on the basis of the typeof tree from which they are cut. Hardwoods are from broad-leaved,deciduous trees. Softwoods are from conifers, which have needle- orscalelike leaves and are, with few exceptions, evergreens. These termsdo not refer to the relative hardnesses of the woods in these twoclasses. Hardwood lumber is available in three basic categories: fac-tory lumber; dimension lumber, or dimension parts; and fin-ished market products. The important difference between factorylumber and dimension parts is that factory lumber grades reflect theproportion of the pieces that can be cut into useful smaller pieces,while the dimension grades are based on use of the entire piece.

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Finished market products are graded for their end use with little or noremanufacturing. Examples of finished market products are flooring,siding, ties, timbers, trim, molding, stair treads, and risers. The rulesadopted by the National Hardwood Lumber Association are consideredstandard in grading factory lumber. The grades from the highest to thelowest quality are as follows: firsts, the top quality, and seconds, bothof which are usually marketed as one grade called firsts and seconds(FAS); selects; and common grades No. 1, No. 2, No. 3A, and No. 3B.Sometimes a grade is further specified, such as FAS one face, whichmeans that only one face is of the FAS quality. Another designation,WHND, sometimes used, means that wormholes are not considereddefects in determining the grade. Dimension lumber, generally gradedunder the rules of the Hardware Dimension ManufacturersAssociation, are of three classes: solid dimension flat stock, kiln-drieddimension flat stock, and solid dimension squares. Each class may berough, semifabricated, or fabricated. Rough dimension blanks are usu-ally kiln-dried and are supplied sawn and ripped to size. Surfaced orsemifabricated stock has been further processed by gluing, surfacing,etc. Fabricated stock has been completely processed for the end use.Solid dimension flat stock has five grades: clear—two faces, clear—oneface, paint, core, and sound. Squares have three grades if rough (clear,select, sound) and four if surfaced (clear, select, paint, sound).

There are two major categories of softwood lumber: constructionand remanufacture. Construction lumber is of three general types:stress-graded; non-stress-graded, also referred to as yard lumber;and appearance lumber. Stress-graded lumber is structural lum-ber never less than 2 in (5 cm) thick, intended for use where definitestrength requirements are specified. The allowable stresses specifiedfor stress-graded lumber depend on the size, number, and placementof defects. Because the location of defects is important, the piece mustbe used in its entirety for the specified strength to be realized. Stress-graded products include timbers, posts, stringers, beams, decking,and some boards.

Typical non-stress-graded lumber items include boards, lath,battens, cross-arms, planks, and foundation stock. Boards, some-times referred to as commons, are one of the more important non-stress-graded products. They are separated into three to five dif-ferent grades, depending upon the species and lumber manufacturingassociation involved. Grades may be described by number (No. 1, No.2) or by descriptive terms (construction, standard). First-grade boardsare usually graded primarily for serviceability, but appearance is alsoconsidered. Second- and third-grade boards are often used togetherfor such purposes as subfloors and sheeting. Fourth-grade boards areselected not for appearance but for adequate strength. The appear-

1044 WOOD




ance category of construction lumber includes trim, siding, flooring,ceiling, paneling, casing, and finish boards. Most appearance lumbergrades are designated by letters and combinations of letters, and arealso often known as select grades. Typical grades of lumber remanu-facture are the factory grades and industrial clears. Factory selectand select shop are typical high grades of factory lumber, followed byNo. 1, No. 2, and No. 3 shop. Industrial clears are used for cabinetstock, door stock, and other products where excellent appearance,mechanical and physical properties, and finishing characteristics areimportant. The principal grades are B&BTR, C, and D.

Metallized wood is wood treated with molten metal so that thecells of the wood are filled with the metal. Fusible alloys, with melt-ing points below the scorching point of the wood, are used. The woodis immersed in molten metal in a closed container under pressure.The hardness, compressive strength, and flexural strength of thewood are increased, and the wood becomes an electric conductorlengthwise of the grain. Woods are also metallized with a surfacecoating of metal by vacuum deposition.

Sugar pine is one of the most widely used pattern woods forfoundry patterns. It replaces eastern white pine, which is scarcer andnow usually more costly. Poplar is used for patterns where a firmerwood is desired; cherry or maple is employed where the pattern is tobe used frequently or will be subject to severe treatment. Densifiedwood is also used for patterns required to be very wear-resistant.Mahogany is used for small and intricate patterns where a firm tex-ture and freedom from warpage are needed. However, for small cast-ings made in quantities on gates, aluminum or brass is morefrequently used.

Excelsior is an old trade name, still used, for continuous, curly,fine wood shavings employed as a packing material for breakablearticles. It is light and elastic, and it is also used as a cushioning andstuffing material. It is usually made from poplar, aspen, basswood, orcottonwood. A cord of wood produces about 1,500 lb (680 kg), but itmay be made as a by-product from other woodworking. It is alsocalled wood fiber and wood wool, but these terms more properlyrefer to fibers of controlled size and length used with a resin binderfor molding into handles, knobs, and other imitation wood parts.Several plastics are suitable for imitation wood, also called syntheticwood and plastic lumber. And environmental concerns regardingglobal deforestation have increased prices of certain woods, makingplastics more cost-competitive.

Some wood for special purposes comes from roots or from bushes.The briar used for tobacco pipes is from the roots of the whiteheath, Erica arborea, of north Africa. Substitutes for briar are the

WOOD 1045




burls of the laurel and rhododendron. Yareta, used for fuel in the cop-per region of Chile, is a mosslike, woody plant which grows on thesunny northern mountain slopes at altitudes above 12,000 ft (3,658m) and requires several hundred years to reach a useful size.

WOOD FLOUR. Finely ground dried wood employed as a filler and asreinforcing material in molding plastics and in linoleum, and as anabsorbent for nitroglycerin. It is made largely from light-colored soft-woods, chiefly pine and spruce, but maple and ash flours are pre-ferred where no resin content is desired. Woods containing essentialoils, such as cedar, are not suitable. Wood flour is produced from saw-dust and shavings by grinding in burr mills. It has the appearance ofwheat flour. The sizes commonly used are 40, 60, and 80 mesh; thefinest is 140 mesh. Grade 1, used as a filler in rubber and plastics,has a particle size of 60 mesh and a specific gravity of 1.25, but 80and 100 mesh are also used for plastic filler. Since wood flour absorbsthe resin or gums when mixed in molding plastics and sets hard, it issometimes mixed with mineral powders to vary the hardness andtoughness of the molded product.

Vast quantities of sawdust are obtained in the sawmill areas.Besides being used as a fuel, it is employed for packing, for finishingmetal parts in tumbling machines, for making particleboard, and fordistilling to obtain resins, alcohols, sugars, and other chemicals.Some sawdust is pulped, and as much as 20% of such pulp can beused in kraft paper without loss of strength. Hickory, walnut, andoak sawdusts are used for meat smoking, or for the making of liq-uid smoke, which is produced by burning the sawdust and absorb-ing the smoke into water. For the rapid production of bacon andother meats, immersion in liquid smoke imitates the flavor ofsmoked meat. Some sawdust is used for agricultural mulch and fer-tilizer by chemical treatment to accelerate decay. Bark fuel isshredded bark, flash-dried and pelletized with powdered coal.Particleboard, made by compressing sawdust or wood particleswith a resin binder into sheets, has uniform strength in all direc-tions, and a smooth, grainless surface. When used as a core forveneer panels, it requires no cross-laminating. Mechanical pulp fornewsprint can be made from sawdust but the quantity available isusually not sufficient. The material known as ground wood, offine-mesh fibers, is made from cord wood, about 1 ton of fibers beingproduced from one cord of pulpwood. Plastic wood, usually mar-keted as a paste in tubes for filling cavities or seams in wood prod-ucts, is wood flour or wood cellulose compounded with a syntheticresin of high molecular weight that will give good adhesion but notpenetrate the wood particles to destroy their nature. The solvent is

1046 WOOD FLOUR




kept low to reduce shrinkage. When cured in place, the material canbe machined, polished, and painted.

WOOD PRESERVATIVES. These fall into two general classes: oils, suchas creosote and petroleum solutions of pentachlorophenol; andwaterborne salts that are applied as water solutions. Coal tar cre-osote, a black or brownish oil made by distilling coal tar, is the oldestand still one of the more important and useful wood preservatives.Because it has recently been classified as a carcinogen, its use isexpected to decrease. Its advantages are high toxicity to wood-destroying organisms; relative insolubility in water and lowvolatility, which impart to it a great degree of permanence under themost varied use conditions; ease of application; ease with which itsdepth of penetration can be determined; general availability and rela-tively low cost; and long record of satisfactory use.

Creosotes distilled from tars other than coal tar are used to someextent for wood preservation. For many years, either cold tar orpetroleum oil has been mixed with cold tar creosote in various pro-portions to lower preservative costs.

Water-repellent solutions containing chlorinate phenols, principallypentachlorophenol, in solvents of the mineral spirit type have beenused in commercial treatment of wood by the millwork industry sinceabout 1931. Pentachlorophenol solutions for wood preservation gener-ally contain 5% (by weight) of this chemical, although solutions withvolatile solvents may contain lower or higher concentrations.Preservative systems containing water-repellent components are soldunder various trade names, principally for the dip or equivalent treat-ment of window sash and other millwork. According to federal specifi-cations the preservative chemicals may not contain less than 5%pentachlorophenol.

Standard wood preservatives used in water solution include acidcopper chromate, ammoniacal copper arsenite, chromated cop-per arsenate, zinc naphthenate, chromated zinc chloride, andfluor chrome arsenate phenol. These preservatives are oftenemployed when cleanliness and paintability of the treated wood arerequired. The chromated zinc chloride and fluor chrome arsenate phenolformulations resist leaching less than preservative oils, and are seldomused where a high degree of protection is required for wood in groundcontact or for other wet installations. Several formulations involvingcombinations of copper, chromium, and arsenic have shown high resis-tance to leaching and very good performance in service. The ammonia-cal copper arsenite and chromated copper arsenate are included inspecifications for such items as building foundations, building poles,utility poles, marine piling, and piling for land and freshwater use.

WOOD PRESERVATIVES 1047




Organic sulfones are another class of wood preservatives offering highdegrees of protection. One such product is diiodomethyl p-tolyl sul-fone, with trade name Amical, from Angus Chemical Co.

WOOL. The fine, soft, curly hair or fleece of the sheep, alpaca, vicuña,certain goats, and a few other animals. The specific designation woolalways means the wool of sheep. Sheep’s wool is one of the mostimportant commercial fibers because of its good physical qualities andits insulating value, especially for clothing, but it now constitutes onlyabout 10% of the textile fiber market. It is best known for its use inclothing fabrics, called woolens. These are designated under a varietyof very old general trade names such as a loosely woven fabric calledflannel, or the fine, smooth fabric known as broadcloth. Cheviot is aclose-napped, twill-woven fabric, and tweed is a woolen fabric with acoarse surface, usually with a herringbone-twill weave. Serge is atwill-woven worsted fabric. Worsteds are wool fabrics made fromcombed-wool yarn, usually from long, smooth wool. Wool is alsoemployed for packings and for insulation, either loose or felted, and formaking felts. The average amount of wool shorn from sheep in theUnited States is 8.1 lb (3.7 kg) per animal.

Wool differs from hair in fineness and its felting and spinning prop-erties. The latter are due to the fine scales of the wool fibers. Thefinest short-staple wool has as many as 4,000 scales to the inch (2.5cm), and the average long-staple wool has about 2,000 scales per inch(2.5 cm). These scales give wool its cohesive qualities. Some animalshave both wool and hair, while others have wool only when young.There is no sharp dividing line between wool and hair.

Wool quality is by fineness, softness, length, and scaliness. Fiberdiameters vary from 0.0025 to 0.005 in (0.0064 to 0.013 cm). Longwools are generally heavy. Fibers below 3 in (7.6 cm) in length areknown as clothing wool, and those from 3 to 7 in (7.6 to 17.8 cm) arecalled combing wools. Long wools are fibers longer than 7 in (17.8cm). The term apparel wool generally means clothing wool of fineweaving quality from known sources. Fleece wool is the unscouredfiber. It may contain as much as 65% grease and dirt, but this is theform in which wool is normally shipped because it then has the pro-tection of the wool fat until it is manufactured. Wool is very absorbentto moisture and will take up about 33% of its weight of water, and insome areas moisture and dirty grease are added to fleece wool toincrease weight. Carpet wools are usually long, nonresilient fibersfrom sheep bred in severe climates, such as the Mongolian wool.The only breed of sheep developed for wool alone is the merino. InAustralia the corriedale and the polworth sheep are dual-purposeanimals for wool and meat.

1048 WOOL




The finest of sheep wools come from the merino sheep, but thesevary according to the age of breeding of the animal. The Lincolnsheep produces the longest fiber. It is lustrous but very coarse.Luster of wool depends upon the size and smoothness of the scales,but the chemical composition is important. The molecular chains arelinked with sulfur, and when sulfur is fed to the sheep, in some defi-cient areas the quality of the wool is improved. Crimpiness in wool isdue to the open formation of the scales. A fine merino will have 24crimps per inch (2.5 cm), whereas a coarse crossbreed will have only 6per inch (2.5 cm). Strength of wool fibers often depends upon thehealth of the animal and the feeding.

One-quarter of the world production of wool is in Australia.Argentina ranks second in production, with the United States third.But the United States is a lamb-eating nation, and a large proportionof the animals are slaughtered when 4 to 8 months old, and most ofthe others are kept only one season for one crop of wool. New Zealand,Uruguay, Russia, and England are also important producers. Englandis the center of wool-sheep breeding, with more varieties than anyother country. In general, warm climates produce fine wools, and hotclimates produce thin, wiry wools, but the fundamental differencescome from the type of animal and the feeding. The reused wool fromold cloth was originally called shoddy, but the name has an opprobri-ous signification in the United States, and is not used by manufactur-ers to designate the fabrics made from reclaimed wool. Shoddy is usedin mixtures with new wool for clothing and other fabrics. Extractwool is shoddy that is recovered by dissolving out the cotton fibers ofthe old cloth with sulfuric acid. Short fibers of shoddy, less than 0.5 in(1.27 cm), are known as mungo fibers. They are used in woolenblends to obtain a napped effect. Reprocessed wool is fiber obtainedfrom waste fabric which has not been used. Noils are short fibers pro-duced in the combining of wool tops for making worsteds. They areused for woolen goods and felt. Zeset, of Du Pont, a shrinkproofingagent for wools, is a variant of Surlyn T, a terpolymer of 70% ethyl-ene, 6 methacryloyl chloride, and 24 vinyl acetate. It prevents shrink-age and pilling under ordinary laundry methods, does not affect color,and increases the tensile strength of the fiber. But all resinous addi-tives tend to harden the fiber and lessen the drape and feel.Conversely, each dry cleaning of wool fabric decreases the natural oilcontent and hardens the fiber.

WOOL GREASE. A brownish, waxy fat of a faint, disagreeable odor,obtained as a by-product in the scouring of wool. The purified greasewas formerly known as degras and was used for leather dressing, inlubricating and slushing oils, and in soaps and ointments; but it is now

WOOL GREASE 1049




largely employed for the production of lanolin and its derivatives,chiefly for cosmetics. Wool grease contains lanoceric acid;lanopalmic acid, C15H30O3; and lanosterol, a high alcohol related tocholesterol. All of these can be broken down into derivatives.

Lanolin is a purified and hydrated grease, also known as lanain,and in pharmacy as lanum and adeps lanae. It has a melting pointof about 104°F (40°C) and is soluble in alcohol. Lanolin is basically awax consisting of esters of sterol alcohols combined with straight-chain fatty acids, and with only a small proportion of free alcohols. Itcontains about 95% of fatty acid esters, but its direct use as an emol-lient depends on the 5% of free alcohols and acids. However, morethan 30 derivatives are obtained from lanolin, and these are used inblends to give specific properties to cosmetics. They are often mar-keted under trade names, and some of the ingredients may be synthe-sized from raw materials other than wool grease, or chemicallyaltered from wool-grease derivatives.

A variety of products used in cosmetics and pharmaceuticals aremade by fractionation or chemical alteration of lanolin. They are alsouseful in compounding plastics and industrial coating, but are gener-ally too scarce and expensive for these purposes. Ethoxylated lano-lin and ethoxylated lanolin alcohols are used in water-solubleemulsions and conditioners. Solulan is a general trade name forthese materials. Lanolin oil and lanolin wax are made by solventfractionation of lanolin. Viscolan and Waxolan are these products.Isopropyl lanolates, with trade name Amerlate, are soft,hydrophylic solids which liquefy easily and are used in cosmetics asemollients, emulsifiers, and pigment dispersants. Amerlate LFA isderived from lanolin hydroxy acids containing iso-acids. The highhydroxyl content produces the emollient and emulsifying qualities.Barium lanolate, made by saponification, is used as an anticorro-sion agent. It is antiphobic and is also used as an anticaking agent. Ina 25% barium concentration it is used for hard lubricating grease.

Ethoxylan is an ethylene oxide derivative of lanolin, soluble inwater and in alcohol, and used in shampoos. Ceralan is a waxy solidmelting at 131°F (55°C) to an amber-colored, viscous liquid. It is amixture of monohydroxyl alcohols, obtained by splitting lanolin, andcontains 30% sterol, and free cholesterol. It forms water-in-oil emul-sions and is used in cosmetics as a dispersing and stiffening agentand as an emollient. Acetylated lanolin is made by reacting lanolinwith polyoxyethylenes. They are clear, nongreasy liquids soluble inwater, oils, and alcohol. The acetylated lanolin is hydrophobic and oil-soluble, and is used as an odorless, nontacky emollient in cosmet-ics. Acylan, from Croda Chemicals, is a soft solid with a bland odorthat is employed in baby products, hair grooms, creams, and pharma-

1050 WOOL GREASE




ceuticals. Oil-based solutions of Acylan are clear, forming soft, waxy,hydrophobic films. Satulan of the same firm is a hydrogenatedlanolin useful in products for skin protection.

Veriderm, of Upjohn Co., is a substitute for lanolin as an emol-lient. It contains about the same percentage of triglycerol esters offatty acids, free cholesterol, and saturated and unsaturated hydrocar-bons as occurs in the natural human skin oils. Cholesterol is one ofthe most important of the complex sterols, or zoosterols, from ani-mal sources. It is produced from lanolin, but also from other sources,and used in drugs and cosmetics. Amerchol L-101 is a liquid non-ionic cholesterol containing other sterols. Wool grease from the scour-ing of wool was originally called Yorkshire grease. Moellon degrasis not wool grease, but is a by-product of chamois leather making. Thesheepskins are impregnated with fish oil, and when the tanning iscomplete, they are soaked in warm water and the excess oil is pressedout to form the moellon degras.

WROUGHT IRON. Commercially pure iron made by melting white castiron and passing an oxidizing flame over it, leaving the iron in aporous condition which is then rolled to unite it into one mass. Asthus made, it has a fibrous structure, with fibers of slag through theiron in the direction of rolling. It is also made by the Aston process ofshooting Bessemer iron into a ladle of molten slag. Modern wroughtiron has a fine dispersion of silicate inclusions which interrupt thegranular pattern and give it a fibrous nature.

The value of wrought iron is in its corrosion resistance and ductil-ity. It is used chiefly for rivets, staybolts, water pipes, tank plates,and forged work. Minimum specifications for ASTM wrought ironcall for a tensile strength of 40,000 lb/in2 (276 MPa), yield strength of24,000 lb/in2 (165 MPa), and elongation of 12%, with carbon not over0.08%, but the physical properties are usually higher. Wrought iron4D has only 0.02% carbon with 0.12 phosphorus, and the fine fibersare of a controlled composition of silicon, manganese, and phospho-rus. This iron has a tensile strength of 48,000 lb/in2 (331 MPa), elon-gation 14%, and Brinell hardness 105. Mn wrought iron has 1%manganese for higher impact strength.

Ordinary wrought iron with slag may contain frequent slag cracks,and the quality grades are now made by controlled additions of sili-cate, and with controlled working to obtain uniformity. But for tanksand plate work, ingot iron is now usually substituted. Merchant bariron is an old name for wrought-iron bars and rods made by faggot-ing and forging. Iron-fibered steel is soft steel with fine iron wireworked into it. Staybolt iron may be wrought iron, but was origi-nally puddled charcoal iron. Lewis iron, for staybolts, is highly

WROUGHT IRON 1051




refined, puddled iron with a tensile strength of 52,000 lb/in2 (359MPa) and elongation of 30%.

The Norway iron formerly much used for bolts and rivets was aSwedish charcoal iron brought to America in Norwegian ships.This iron, with as low as 0.02% carbon, and extremely low silicon, sul-fur, and phosphorus, was valued for its great ductility and toughnessand for its permeability qualities for transformer cores. Commercialwrought iron is now usually ingot iron or fibered low-carbon steel.

YARNS. Assemblages or bundles of fibers twisted or laid together toform continuous strands. They are produced with either filaments orstaple fibers. Single strands of yarns can be twisted together to form plyor plied yarns, and ply yarns in turn can be twisted together to formcabled yarn or cord. Important yarn characteristics related to behaviorare fineness (diameter or linear density) and number of twists per unitlength. The measuring of fineness is commonly referred to as yarnnumber. Yarn numbering systems are somewhat complex, and they aredifferent for different types of fibers. Essentially, they provide a mea-sure of fineness in terms of weight per unit or length per unit weight.

Cotton yarns are designated by numbers, or counts. The stan-dard count of cotton is 840 yd/lb (1,690 m/kg). Number 10 yarn istherefore 8,400 yd/lb (16,900 m/kg). A No. 80 sewing cotton is 80840,or 67,200 yd/lb (135,500 m/kg).

Linen yarns are designated by the lea of 300 yd (274 m). A10-count linen yarn is 10 300, or 3,000 yd/lb (6,048 m/kg).

The size or count of spun rayon yarns is on the same basis as cot-ton yarn. The size or count of rayon filament yarn is on the basis ofthe denier, the rayon denier being 492 yd (450 m), weighing 0.00011lb (5 cg). If 492 yd of yarn weighs 0.00011 lb, it has a count of 1denier. If it weighs 0.0011 lb (10 cg), it is No. 2 denier. Rayon yarnsrun from 15 denier, the finest, to 1,200 denier, the coarsest.

Reeled silk yarn counts are designated in deniers. The interna-tional denier for reeled silk is 547 yd (500 m) of yarn weighing0.00011 lb. If 547 yd weighs 0.0022 lb (1 g), the denier is No. 20. Spunsilk count under the English system is the same as the cotton count.Under the French system the count is designated by the number ofskeins weighing 2.205 lb (1 kg). The skein of silk is 1,094 yd (1,000 m).

A ply yarn is one that has two or more yarns twisted together. Atwo-ply yarn has two separate yarns twisted together. The separateyarns may be of different materials, such as cotton and rayon. A six-ply yarn has six separate yarns. A ply yarn may have the differentplies of different twists to give different effects. Ply yarns are strongerthan single yarns of the same diameter. Tightly twisted yarns makestrong, hard fabrics. Linen yarns are not twisted as tightly as cotton

1052 YARNS




because the flux fiber is longer, stronger, and not as fuzzy as the cot-ton. Filament rayon yarn is made from long, continuous rayonfibers, and it requires only slight twist. Fabrics made from filamentyarn are called twalle. Monofilament is fiber heavy enough to beused alone as yarn, usually more than 15 denier. Tow consists of mul-tifilament reject strands suitable for cutting into staple lengths forspinning. Spun rayon yarn is yarn made from staple fiber, which israyon filament cut into standard short lengths.

YUCCA FIBER. The fiber obtained from the leaves of a number ofdesert plants of the genus Yucca of the lily family native to the south-western United States and northern Mexico. The fiber is similar tofibers from agave plants and is often confused with them and withistle. The heavier fibers are used for brushes, and the lighter fibersare employed for cordage and burlap fabrics. In Mexico the wordpalma designates yucca fibers and grades of istle as well as palm-leaffibers. Palma samandoca is fiber from the plant Samuela carner-osana, the date yucca. It is also called palma istle. Palmilla fiberis from Y. elata. Palma pita is a fiber from Y. treculeana. Pita fiberused for coffee bags in Colombia and Central America is from a differ-ent plant. Other yucca fibers come from the plants Y. glauca, Y. bac-cata, and Y. gloriosa. Some varieties of Y. baccata also yield ediblefruits. The roots of species of yucca yield saponin which is alsoobtained as a by-product in extracting the yucca fiber.

ZINC. A bluish-white, crystalline metal, symbol Zn, with a specificgravity of 7.13, melting at 788°F (420°C) and boiling at 1662°F(906°C). The commercially pure metal has a tensile strength, cast, ofabout 9,000 lb/in2 (62 MPa) with elongation of 1%, and the rolledmetal has a strength of 24,000 lb/in2 (165 MPa) with elongation of35%. But small amounts of alloying elements harden and strengthenthe metal, and it is seldom used alone. Zinc is used for galvanizingand plating; for making brass, bronze, and nickel silver; for electricbatteries; for die castings; and in alloyed sheets for flashings, gutters,and stamped and formed parts. The metal is harder than tin, and anelectrodeposited plate has a Vickers hardness of about 45. Zinc is alsoused for many chemicals.

The old name spelter, often applied to slab zinc, came from thename spailter used by Dutch traders for the zinc brought from China.The first zinc produced in the United States in 1838 came from NewJersey ore. Sterling spelter was 99.5% pure. Special high-grade zincis distilled, with a purity of 99.99%, containing no more than 0.006%lead and 0.004 cadmium. High-grade zinc, used in alloys for die cast-ing, is 99.9% pure, with 0.07 maximum lead. Brass special zinc is

ZINC 1053




99.10% pure, with 0.06 maximum lead and 0.5 maximum cadmium.Prime western zinc, used for galvanizing, contains 1.60% maxi-mum lead and 0.08 maximum iron. Zinc crystals produced for elec-tronic uses are 99.999% pure metal.

On exposure to the air, zinc becomes coated with a film of carbonateand is then very corrosion-resistant. Zinc foil comes in thicknessesfrom 0.001 to 0.006 in (0.003 to 0.015 cm). It is produced by electrode-position on an aluminum drum cathode and stripping off on a collect-ing reel. But most of the zinc sheet contains a small amount ofalloying elements to increase the physical properties. Slight amountsof copper and titanium reduce grain size in sheet zinc. In cast zinc thehexagonal columnar grain extends from the mold face to the surfaceor to other grains growing from another mold face, and even veryslight additions of iron can control this grain growth. Aluminum isalso much used in alloying zinc. In zinc used for galvanizing, a smalladdition of aluminum prevents formation of brittle alloy layer,increases ductility of the coating, and gives a smoother surface. Smalladditions of tin give bright, spangled coatings.

Zinc has 12 isotopes, but the natural material consists of 5 stableisotopes, of which nearly half is zinc 64. The stable isotope zinc 67,occurring to the extent of about 4% in natural zinc, is sensitive to tinyvariations in transmitted energy, giving off electromagnetic radia-tions which permit high accuracy in measuring instruments. It mea-sures gamma-ray vibrations with great sensitivity and is used in thenuclear clock.

Zinc powder, or zinc dust, is a fine, gray powder of 97% minimumpurity usually in 325-mesh particle size. It is used in pyrotechnics, inpaints, as a reducing agent and catalyst, in rubbers as a secondary dis-persing agent and to increase flexing, and to produce Sherardizedsteel. Sherardizing consists in hot-tumbling steel parts in a closeddrum with the zinc powder. It is a form of galvanizing, and controlledzinc coatings of 0.1 to 0.4 oz/ft2 (0.4 to 1.8 g/cm2) of surface give goodcorrosion protection. In paints, zinc powder is easily wetted by oils. Itkeeps the zinc oxide in suspension and hardens the film. Mossy zinc,used to obtain color effects on face brick, is a spangly zinc powder madeby pouring the molten metal into water. Feathered zinc is a fine gradeof mossy zinc. Photoengraving zinc for printing plates is made frompure zinc with only a small amount of iron to reduce grain size andalloyed with not more than 0.2% each of cadmium, manganese, andmagnesium. Cathodic zinc, used in the form of small bars or platesfastened to the hulls of ships or to underground pipelines to reduce elec-trolytic corrosion, is zinc of 99.99% purity with iron less than 0.0014 toprevent polarization. Merrillite is high-purity zinc dust. Zinc serves asthe anode in the zinc-air battery, which, for powering electric vehi-

1054 ZINC




cles, has demonstrated much greater storage capacity than the com-mon lead-acid battery.

ZINC ALLOYS. Alloys of zinc are mostly used for die castings for deco-rative parts and for functional parts where the load-bearing andshock requirements are relatively low. Since the zinc alloys can becast easily in high-speed machines, producing parts that weigh lessthan brass and have high accuracy and smooth surfaces that requireminimum machining and finishing, they are widely used for suchparts as handles, and for gears, levers, pawls, and other small parts.Zinc alloys for sheet contain only small amounts of alloying elements,with 92 to 98% zinc, and the sheet is generally referred to simply aszinc or by a trade name. The modified zinc sheet is used forstamped, drawn, or spun parts for costume jewelry and electronics,and it contains up to 1.5% copper and 0.5 titanium. The titaniumraises the recrystallization temperature, permitting heat treatmentwithout coarse-grain formation.

Hartzink had 5% iron and 2 to 3 lead, but iron forms variouschemical compounds with zinc and the alloy is hard and brittle.Copper reduces the brittleness. Germania bearing bronze con-tained 1% iron, 10 tin, about 5 each of copper and lead, and the bal-ance zinc. Fenton’s alloy had 14% tin, 6 copper, and 80 zinc; andEhrhard’s bearing metal contained 2.5% aluminum, 10 copper, 1lead, and a small amount of tin to form copper-tin crystals. Bindingmetal, for wire-rope slings, has about 2.8% tin, 3.7 antimony, and thebalance zinc. Pattern metal, for casting gates of small patterns, wasalmost any brass with more zinc and some lead added, but is nowstandard die-casting metal.

Zinc alloys are commonly used for die castings, and the zinc used ishigh-purity zinc known as special high-grade zinc. ASTMAG40A (SAE 903) is the most widely used; others include AC41A(SAE 925), Alloy 7, and ILZRO 16. All typically contain about 4%aluminum, small amounts of copper and very small amounts of mag-nesium. AG40A has a density of 0.24 lb/ft3 (6,643 kg/m3), an electricalconductivity 27% that of copper, a thermal conductivity of 65 Btu/(ft h °F) [113 W/(m K)], an ultimate tensile strength of 41,000 lb/in2

(283 MPa), and a Brinell hardness of 82. AC41A is stronger [48,000lb/in2 (331 MPa)] and harder (Brinell 91), a trifle less electrically andheat-conductive, and similar in density. The alloys have much greaterunnotched Charpy impact strength than either die-cast aluminum ormagnesium alloys, but are not especially heat-resistant, losing aboutone-third of their strength at temperatures above about 200°F (93°C).Both alloys have found wide use for auto and appliance parts, espe-cially chromium-plated parts, as well as for office equipment parts,

ZINC ALLOYS 1055




hardware, locks, toys, and novelties. Alloy 7 is noted primarily for itsbetter castability and the smoother surface finish it provides. It is asstrong as AG40A, though slightly less hard, and more ductile. ILZRO16 is not nearly as strong [33,000 lb/in2 (228 MPa)], but more creep-resistant at room and elevated temperatures.

The most recent casting alloys are three high-aluminum zinccasting alloys for sand and permanent-mold casting: ZA-8, ZA-12,and ZA-27, the numerals in the designations indicating approxi-mate aluminum content. They also contain more copper thanAG40A and AC41A, from 0.5 to 1.2% in ZA-12 to 2 to 2.5 in ZA-27,and a bit less magnesium. As sand-cast, ultimate tensile strengthsrange from 36,000 to 40,000 lb/in2 (248 to 276 MPa) for ZA-8 and58,000 to 64,000 lb/in2 (400 to 441 MPa) for ZA-27. Unlike the com-mon die-casting alloys, the ZA alloys also exhibit clearly definedtensile yield strengths: from 28,000 lb/in2 (193 MPa) minimum forsand-cast ZA-8 to 53,000 lb/in2 (365 MPa) for sand-cast ZA-27.Tensile modulus is roughly 12106 lb/in2 (83,000 MPa). Also,because of their greater aluminum content, they are lighter inweight than the die casting alloys. Zinc-copper-aluminum alloysdeveloped at General Motors and designated ACuZinc alloys, arenoted for high tensile strength and superior creep resistance.ACuZinc 5, with 5% copper and 3 aluminum, has a tensile strengthof 59,000 lb/in2 (407 MPa). ACuZinc 10, with 10% copper and 3.5aluminum, has a creep strength of 8,000 lb/in2 (55 MPa) at 120°F(49°C) for 0.2% creep in 10,000 h.

Manganese-zinc alloys, with up to 25% manganese, for high-strength extrusions and forgings, are really 60–40 brass with part ofthe copper replaced by an equal amount of manganese, and are classi-fied with manganese bronze. They have a bright white color and arecorrosion-resistant. Zam metal, for zinc-plating anodes, is zinc withsmall percentages of aluminum and mercury to stabilize against acidattack. A zinc-aluminum-oxide coating imparts corrosion resis-tance to steel underhood and underbody auto parts. Developed byMetal Coatings International, it consists of zinc and aluminum flakesin a waterborne, neutral pH solution that complies with regulationsgoverning emission of volatile organic compounds. It is applied bydipping or spraying. Baking during curing forms an insoluble matrixof silicon, aluminum, and zinc oxides between the flakes for corrosionprotection.

CorroBan, of Pure Coatings Inc., is an electrolytically depositedcoating of 82 to 89% zinc, balance nickel, which resists corrosion aswell as cadmium plating. Zinc solders are used for joining alu-minum. The tin-zinc solders have 70 to 80% tin, about 1.5 alu-minum, and the balance zinc. The working range is 500 to 590°F

1056 ZINC ALLOYS




(260 to 310°C). Zinc-cadmium solder has about 60% zinc and 40cadmium. The pasty range is between 510 and 599°F (266 and315°C).

A group of wrought alloys, called superplastic zinc alloys,have elongations of up to 2,500% in the annealed condition. Thesealloys contain about 22% aluminum. One grade can be annealedand air-cooled to a strength of 71,000 lb/in2 (490 MPa). Parts madeof these alloys have been produced by vacuum forming and by acompression molding technique similar to forging but requiringlower pressures.

ZINC CHEMICALS. With the exception of the oxide, the quantities ofzinc compounds consumed are not large compared with many othermetals, but zinc chemicals have a very wide range of use, being essen-tial in almost all industries and for the maintenance of animal andvegetable life. Zinc is a complex element and can provide someunusual conditions in alloys and chemicals.

Zinc oxide, ZnO, is a white, water-insoluble, refractory powdermelting at about 3587°F (1975°C), having a specific gravity of 5.66. Itis much used as a pigment and accelerator in paints and rubbers. Itshigh refractive index, about 2.01, absorption of ultraviolet light, andfine particle size give high hiding power in paints, and make it alsouseful in such products as cosmetic creams to protect against sun-burn. Commercial zinc oxide is always white, and in the paint indus-try is also called zinc white and Chinese white. But with a smallexcess of zinc atoms in the crystals, obtained by heat treatment, thecolor is brown to red.

In paints, zinc oxide is not as whitening as lithopone, but it resiststhe action of ultraviolet rays and is not affected by sulfur atmo-spheres, and is thus valued in outside paints. Leaded zinc oxide,consisting of zinc oxide and basic lead sulfate, is used in paints, butfor use in rubber the oxide must be free of lead. The lead-free varietyis also called French process zinc oxide. Canfelzo is one suchproduct, from Pigment & Chemical Corp. In insulating compoundszinc oxide improves electrical resistance. In paper coatings it givesopacity and improves the finish. Zinc-white paste for paint mixingusually has 90% oxide and 10 oil. Zinc oxide stabilizers, composedof zinc oxides and other chemicals, can be added to plastic moldingcompounds to reduce the deteriorating effects of sunlight and othertypes of degrading atmospheres.

Zinc oxide crystals are used for transducers and other piezoelec-tric devices. The crystals are hexagonal and are effective at elevatedtemperatures, as the crystal has no phase change up to its disassocia-tion point. The resistivity range is 0.2 to 3.9 in (0.5 to 10 cm).

ZINC CHEMICALS 1057




Zinc oxide has luminescent and light-sensitive properties which areutilized in phosphors and ferrites. But the oxygen-dominated zincphosphors used for radar and television are modifications of zinc sul-fide phosphors. The zinc sulfide phosphors which produce lumines-cence by exposure to light are made with zinc sulfide mixed withabout 2% sodium chloride and 0.005 copper, manganese, or other acti-vator, and fired in a nonoxidizing atmosphere. The cubic crystal struc-ture of zinc sulfide changes to a stable hexagonal structure at 1868°F(1020°C), but both forms have the phosphor properties. Thin filmsand crystals of zinc selenide with purities of 99.999% are used forphoto- or electroluminescent devices. Zinc selenide is also used foroptical lenses in CO2 laser systems. Zinc sulfide is a white powder ofcomposition ZnS H2O, and is also used as a paint pigment, forwhitening rubber, and for paper coating. Cryptone is zinc sulfide forpigment use in various grades, some grades containing barium sul-fate, calcium sulfide, or titanium dioxide. Multilayer coatings of zincsulfide and yttria protect zinc sulfide infrared sensor windows of mis-siles and military aircraft from harsh flight environments.

Zinc is an amphoteric element, having both acid and basic prop-erties, and it combines with fatty acids to form metallic soaps, or withthe alkali metals or with ammonia to form zincates. Sodium zin-cate is used for waterproofing asbestos-cement shingles. Zincstearate, ZN(C18H35O2)2, is a zinc soap in the form of a fine, whitepowder used in paints and in rubber. A USP grade of 325 mesh isused in cosmetics. Aquazinc and Liquizinc, of Rubba, Inc., are zincstearate dispersions in water used as an antitack agent in millingrubber. Zinc acetate, Zn(C2H3O2)2, is a white solid partly soluble inwater, used as a mordant, as a wood preservative, in porcelain glazes,and as a mild antiseptic in pharmaceuticals.

Zinc sulfate, ZnSO4 7H2O, is the chief material for supplying zincin fertilizers, agricultural sprays, and animal feeds. For these pur-poses it is used in the form of white vitriol containing 22% zinc, or asthe monohydrate, ZnSO4 H2O, containing 37% zinc. Zink Gro is awater-soluble grade for dry-blended fertilizers for correction of zincdeficiencies. It is from Eagle-Picher Industries, Inc. Zinc chloride, awhite, crystalline, water-soluble powder, ZNCl2, was formerly animportant preservative for wood, and railway crossties treated withthe material were called Burnettized wood. But it is highly solubleand leaches out of the wood, and is now chromated and copperizedwith sodium bichromate and cupric chloride. Copperized CZC, ofKoppers Co., Inc., for treating wood against rot and termites, is cop-perized chromated zinc chloride. zinc chloride is also used for vulcan-izing fiber, as a mordant, in mercerizing cotton, in dry batteries, indisinfecting, and in making many chemicals. Spirits of salts andbutter of zinc are old names for the material.

1058 ZINC CHEMICALS




Zinc chromate, used chiefly as a pigment and called zinc yellowand buttercup yellow, is stable to light and in sulfur atmospheres,but has a lower tinting strength than chrome yellow, although it isless subject to staining and discoloration. It is a crystalline powder ofspecific gravity 3.40. It is only slightly soluble in water, but willabsorb 24 lb (11 kg) of linseed oil per 100 lb (45 kg). Zinc chromatesare made by reacting zinc oxide with chromate solutions, and theymay vary; but the usual composition is 4ZnO 4CrO3 K2O 3H2O.Zinc bichromate, ZnCr2O7, is an orange-yellow pigment. The zincperoxide used in dental pastes and cosmetics as a mild antiseptic isa white powder, ZnO2, containing 8.5% active oxygen. Organic salts ofzinc that have achieved commercial prominence are zinc naphthen-ate and zinc pyrithione. The former is available in 6 and 8% gradesfor prevention of wood rot and decay, in solvent- and water-dispersibleformulations. Nap-All and M-Gards are from Mooney Chemicals,Inc., and Zinclear is from Standard Tar Products Co. Olin Corp.’sZinc Omadine, a zinc pyrithione, is employed as an antidandruffagent, for preserving cosmetics, in metalworking fluids, and as anantimicrobial on textiles.

Fluidized zinc titanate (FZT) can serve as a sorbent to remove99% of the sulfur dioxide in power plants using sulfur-containing coal.In a process developed at Research Triangle Institute with the U.S.Department of Energy, the sorbent can be continuously recirculatedand the sulfur absorbed recovered from the regenerator off-gas. Useof the sorbent is an alternative to cooling the coal gas to remove sul-fur, then having to reheat it to produce electricity.

ZINC ORES. The metal zinc is obtained from a large number of ores,but the average zinc content of the ores in the United States is onlyabout 3%, so that they are concentrated to contain 35 to 65% beforetreatment. The sulfide ores are marketed on the basis of 60% zinccontent, and the oxide ores on the basis of 40% zinc content.Sphalerite, or zinc blende, is the most important ore and is foundin quantities in Missouri and surrounding states and in Europe.Sphalerite is a zinc sulfide, ZnS, containing theoretically 67% zinc. Ithas a massive crystalline or granular structure and a Mohs hardnessof about 4. When pure, its color is white; it colors yellow, brown,green, to black with impurities. The ores from New York State areround and concentrated by flotation to an average of 58% zinc and 32sulfur, which is then concentrated by roasting to 68 zinc and 1 sulfur.It is then sintered to remove lead and cadmium and finally smeltedwith coke, and the zinc vapor condensed. The Silesian zinc blende,known as wurtzite, contains 15% zinc, 2 lead, and some cadmium.

Calamine is found in New Jersey, Pennsylvania, Missouri, andEurope. It is the ore that was formerly mixed directly with copper for

ZINC ORES 1059




making brass. The ore usually contains only about 3% zinc, and isconcentrated to 35 to 45%, and then roasted and distilled. Calamineis zinc silicate, 2ZnO SiO2 H2O. It is a mineral occurring in crys-tal groups of a vitreous luster, and it may be white, greenish, yellow,or brown. The specific gravity is 3.4, and Mohs hardness 4.5 to 5. Itoccurs in Arkansas with smithsonite, a zinc carbonate ore, ZnCO3.Franklinite is an ore of both the metals zinc and manganese. Itsapproximate composition is (FeZnMo)O (FeMn)2O3, but it showswide variation in the proportions of the different elements. It is foundin the zinc deposits of New Jersey. The zinc is converted into zincwhite, and the residue is smelted to form spiegeleisen. The mineralfranklinite occurs in massive granular structure with a metallic lus-ter and an iron-black color.

The ore zincite is used chiefly for the production of the zinc oxideknown as zinc white employed as a pigment. Zincite has the composi-tion ZnO, containing theoretically 80.3% zinc. The mineral has usuallya massive granular structure with a deep-red to orange streaked color.It may be translucent or almost opaque. Deep-red specimens from theworkings at Franklin, New Jersey, are cut into gemstones for costumejewelry. Willemite is an anhydrous silicate, Zn2SiO4, containing theo-retically 58.5% zinc. When manganese replaces part of the zinc, the oreis called troostite. It is in hexagonal prisms of white, yellow, green, orblue; manganese makes it apple-green, brown, or red. The specific grav-ity is about 4 and Mohs hardness 5.5. The crushed ore is used in makingfluorescent glass. The ore is widely dispersed in the United States.

ZIRCONIA. A white, crystalline powder which is zirconium oxide,ZrO2, with a specific gravity of 5.7, Mohs hardness 6.5, and refractiveindex 2.2. When pure, its melting point is about 5000°F (2760°C), andit is one of the most refractory of the ceramics. It is produced by react-ing zircon sand and dolomite at 2500°F (1371°C) and leaching out thesilicates. The material is used as fused or sintered ceramics and forcrucibles and furnace bricks. From 4.5 to 6% of CaO or other oxide isadded to convert the unstable monoclinic crystal to the stable cubicform with a lowered melting point.

Fused zirconia, used as a refractory ceramic, has a melting point of4620°F (2549°C) and a usable temperature to 4450°F (2454°C). TheZinnorite fused zirconia of Norton Co. is a powder that contains lessthan 0.8% silica and has a melting point of 4900°F (2704°C). A sinteredzirconia can have a specific gravity of 5.4, a tensile strength of 12,000lb/in2 (83 MPa), compressive strength of 200,000 lb/in2 (1,379 MPa), andKnoop hardness of 1,100. Zircoa B is stabilized cubic zirconia used formaking ceramics. Zircoa A is the pure monoclinic zirconia used as apigment, as a catalyst, in glass, and as an opacifier in ceramic coatings.

1060 ZIRCONIA




Zirconia brick for lining electric furnaces has no more than 94%zirconia, with up to 5 calcium oxide as a stabilizer, and some silica.It melts at about 4300°F (2371°C), but softens at about 3600°F(1982°C). The IBC 4200 brick of Ipsen Industries, Inc., is zirconiawith calcium and hafnium oxides for stabilizing. It withstands tem-peratures to 4200°F (2316°C) in oxidizing atmospheres and to3000°F (1849°C) in reducing atmospheres. Zirconia foam is mar-keted in bricks and shapes for thermal insulation. With a porosityof 75% it has a flexural strength above 500 lb/in2 (3 MPa) and acompressive strength above 100 lb/in2 (0.7 MPa). For use in cru-cibles, zirconia is insoluble in most metals except the alkali metalsand titanium. It is resistant to most oxides, but with silica it formsZrSiO4, and with titania it forms ZrTiO4. Since structural disinte-gration of zirconia refractories comes from crystal alteration, thephase changes are important considerations. The monoclinic mater-ial, with a specific gravity of 5.7, is stable to 1850°F (1010°C) andthen inverts to the tetragonal crystal with a specific gravity of 6.1and volume change of 7%. It reverts when the temperature againdrops below 1850°F (1010°C). The cubic material, with a specificgravity of 5.55, is stable at all temperatures to the melting point,which is not above 4800°F (2649°C) because of the contained stabi-lizers. A lime-stabilized zirconia refractory with a tensile strengthof 20,000 lb/in2 (138 MPa) has a tensile strength of 10,000 lb/in2 (69MPa) at 2370°F (1299°C). Stabilized zirconia has a very low coef-ficient of expansion, and white-hot parts can be plunged into coldwater without breaking. The thermal conductivity is only aboutone-third that of magnesia. It is also resistant to acids and alkaliesand is a good electrical insulator. Diamond Z refers to a line of“unbreakable” buttons made of zirconia, fired at 3200°F (1760°C),polished and coated to look like ivory. Developed by Adolph CoorsCo., they are sold by ACX Technologies for high-priced shirts.

Toughening mechanisms, by which a crack in a ceramic can bearrested, complement processing techniques that seek to eliminatecrack-initiating imperfections. Transformation toughening relies ona change in crystal structure (from tetragonal to monoclinic) that zirco-nia or zirconium dioxide (ZrO2) grains undergo when they are subjectedto stresses at a crack tip. Because the monoclinic grains have a slightlylarger volume, they can “squeeze” a crack shut as they expand in thecourse of transformation. Due to ZrO2’s transformation-toughening abil-ities, which impart higher fracture toughness, research interest inengine applications has been high. In order for ZrO2 to be used in high-temperature, structural applications, it must be stabilized or par-tially stabilized to prevent a monoclinic-tetragonal phase change.Stabilization involves the addition of calcia, magnesia, or yttria followed

ZIRCONIA 1061




by some form of heat treatment. PSZ ceramic, the toughest knownceramic, is being investigated for diesel-engine applications.

A new zirconia ceramic being developed is tetragonal zirconiapolycrystal (TZP) doped with Y2O3. Designated Y-TZP, it has themost impressive room-temperature mechanical properties of any zir-conia ceramic. The commercial applications of TZP zirconia includescissors having TZP blades suitable for industrial use for cuttingtough fiber fabrics, e.g., Kevlar, cables, and ceramic scalpels for surgi-cal applications. One unique application is fish knives. The knifeblades are Y-TZP and can be used when the delicate taste of raw fishwould be tainted by slicing with metal-blade knives. Tungsten-car-bide-reinforced Y-TZP, developed by Toray Industries and NipponTungsten Co. of Japan, has five times the thermal conductivity of Y-TZP and high hardness, strength, toughness, and heat resistance.

Magnesia-stabilized PSZ, Mg-PSZ, is fired at a higher tempera-ture than Y-TZP and, thus, develops a larger grain size: 1,970 to 3,940in (50 to 100 m) versus 11.8 to 31.5 in (0.3 to 0.8 m).Consequently, Mg-PSZ is slightly porous while Y-TZP is virtually freeof porosity. However, this porosity does not affect its sealing behaviorin valve applications. Mg-PSZ is not as strong as Y-TZP, but it isslightly tougher and, thus, more resistant to erosion by particleimpingement. Also, Mg-PSZ has not exhibited susceptibility to low-temperature degradation in warm, moist environments even with justtrace amounts of water vapor, which has limited Y-TZP to moisture-free valve applications.

Another zirconia ceramic–developed material is zirconia-tough-ened alumina (ZTA). ZTA zirconia is a composite polycrystallineceramic containing ZrO2 as a dispersed phase (typically about 15 vol-ume %). Close control of initial starting-powder sizes and sinteringschedules is thus necessary in order to attain the desired ZrO2 parti-cle dimensions in the finished ceramic. Hence the mechanical proper-ties of the composite ZTA ceramics limit current commercialapplications to cutting tools and ceramic scissors.

PSZ is also finding application in the transformation toughening ofmetals used in the glass industry as orifices for glass fiber drawing.This material is being termed zirconia grain-stabilized (ZGS)platinum.

Zirconia is produced from the zirconium ores known as zircon andbaddeleyite. The latter is a natural zirconium oxide, but is obtain-able commercially only from Minas Gerais, Brazil. It is also calledzirkite and Brazilite. Zircon is zirconium silicate, ZrO2 SiO2,and comes chiefly from beach sands. The commercial sand is found inFlorida, Brazil, India, Sri Lanka, Australia, and western Africa. Thesands are also called zirkelite and zirconite, or merely zircon

1062 ZIRCONIA




sand. The white zircon sand from India has a zirconia content of 62%and contains less than 1% iron. Beach sands of New South Wales arenaturally concentrated to an average of 74% zircon, but Australianzircon is shipped on a basis of 65% zirconia. Zircon sand may be useddirectly for making firebricks, as an opacifier in ceramics, and formold facings. Clear zircon crystals are valued as gemstones sincethe high refractive index gives great brilliance. The colorless naturalcrystals are called Matura diamonds, and the yellow-red are knownas jacinth.

Zirconia fiber, used for high-temperature textiles, is producedfrom zirconia with about 5% lime for stabilization. The fiber ispolycrystalline, has a melting point of 4700°F (2593°C), and with-stands continuous temperatures above 3000°F (1649°C). Thesefibers are produced by Union Carbide as small as 118 to 394 in (3to 10 m) and are made into fabrics for filter and fuel cell use.Zirconia fabrics are woven, knitted, or felted of short-lengthfibers and are flexible. Ultratemp adhesive, of Aremco Products,for high-heat applications, is zirconia powder in solution. At1100°F (593°C) it adheres strongly to metals and withstands tem-peratures to 4400°F (2427°C). Zircar, of Union Carbide, is zirconiafiber compressed into sheets to a density of 20 lb/ft3 (320 kg/m3). Itwithstands temperatures up to 4500°F (2482°C) and has low ther-mal conductivity. It is used for insulation and for high-temperaturefiltering.

ZIRCONIUM. A silvery-white metal, symbol Zr, having a specificgravity of 6.5 and melting at about 3362°F (1850°C). It is moreabundant than nickel, but is difficult to reduce to metallic form asit combines easily with oxygen, nitrogen, carbon, and silicon. Themetal is obtained from zircon sand by reacting with carbon andthen converting to the tetrachloride, which is reduced to a spongemetal for further production of shapes. The ordinary sponge zirco-nium contains about 2.5% hafnium, which is closely related anddifficult to separate. The commercial metal usually containshafnium, but reactor-grade zirconium, for use in atomic work, ishafnium-free.

Commercially pure zirconium is not a high-strength metal, havinga tensile strength of about 32,000 lb/in2 (221 MPa), elongation 40%,and Brinell hardness 30, or about the same physical properties aspure iron. Because of its low neutron-capture cross section, thermalstability, and corrosion resistance, it is the standard metal for fuel-rodcladding and core components in nuclear reactors. It is employedmostly in the form of alloys but may be had in 99.99% pure single-crystal rods, sheets, foil, and wire for superconductors, surgical

ZIRCONIUM 1063




implants, and vacuum-tube parts. The neutron cross section of zirco-nium is 0.18 barn, compared with 2.4 for iron and 4.5 for nickel. Thecold-worked metal, with 50% reduction, has a tensile strength ofabout 82,000 lb/in2 (565 MPa), with elongation of 18% and Brinellhardness of 95. The unalloyed metal is difficult to roll and is usuallyworked at temperatures to 900°F (482°C). Though nontoxic, the metalis pyrophoric because of its heat-generating reaction with oxygen,necessitating special precautions in handling powder and fine chipsresulting from machining operations.

The metal has a close-packed hexagonal crystal structure, whichchanges at 1583°F (862°C) to a body-centered cubic structure which isstable to the melting point. At 572 to 752°F (300 to 400°C) the metalabsorbs hydrogen rapidly, and above 392°F (200°C) it picks up oxy-gen. At about 752°F it picks up nitrogen, and at 1472°F (800°C) theabsorption is rapid, increasing the volume and embrittling the metal.The metal is not attacked by nitric (except red fuming nitric), sulfu-ric, or hydrochloric acids, but is dissolved by hydrofluoric acid. It alsoresists phosphoric acid, most organic acids including acetic andformic, strong alkalis, and molten salts. And it is one of the few mate-rials that works well in alternating contact with strong acids andbasic environments.

Zirconium powder is very reactive, and for making sintered met-als it is usually marketed as zirconium hydride, ZrH2, containingabout 2% hydrogen which is driven off when the powder is heated to300°C. For making sintered parts, alloyed powders are also used.Zirconium copper, containing 35% zirconium, zirconium nickel,with 35 to 50% zirconium, and zirconium cobalt, with 50% zirco-nium, are marketed as powders of 200 to 300 mesh.

Small amounts of zirconium are used in many steels. It is a pow-erful deoxidizer, removes the nitrogen, and combines with the sul-fur, reducing hot-shortness and giving ductility. Zirconium steelswith small amounts of residual zirconium have a fine grain and areshock-resistant and fatigue-resistant. In amounts above 0.15% thezirconium forms zirconium sulfide and improves the cutting qualityof the steel. Zirconium alloys generally have only small amountsof alloying elements to add strength and resist hydrogen pickup.Zircoloy 2, for reactor structural parts, has 1.5% tin, 0.12 iron,0.10 chromium, 0.05 nickel, and the balance zirconium. Tensilestrength is 68,000 lb/in2 (469 MPa), elongation 37%, and RockwellB hardness 89; at 600°F (316°C) it retains a strength of 30,000lb/in2 (207 MPa).

Small amounts of zirconium in copper give age-hardening andincrease the tensile strength. Copper alloys containing even smallamounts of zirconium are called zirconium bronze. They pour

1064 ZIRCONIUM




more easily than bronzes with titanium, and they have good electri-cal conductivity. Zirconium-copper master alloy for adding zirco-nium to brasses and bronzes is marketed in grades with 12.5 and35% zirconium. A nickel-zirconium master alloy has 40 to 50%nickel, 25 to 30 zirconium, 10 aluminum, and up to 10 silicon and 5iron. Zirconium-ferrosilicon, for alloying with steel, contains 9 to12% zirconium, 40 to 47 silicon, 40 to 45 iron, and 0.20 maximumcarbon, but other compositions are available for special uses. SMZalloy, for making high-strength cast irons without leaving residualzirconium in the iron, has about 75% silicon, 7 manganese, 7 zirco-nium, and the balance iron. A typical zirconium copper for electricaluse is Amzirc. It is oxygen-free copper with only 0.15% zirconiumadded. At 752°F (400°C) it has an electrical conductivity of 37% ofelectrolytic-tough-pitch copper (C11100), tensile strength of 52,000lb/in2 (359 MPa), and elongation of 9%. The softening temperatureis 1076°F (580°C).

Zirconium alloys with high zirconium content have few usesexcept for atomic applications. Zircoloy tubing is used to containthe uranium oxide fuel pellets in reactors since the zirconium doesnot have grain growth and deterioration from radiation. Zirconiaceramics are valued for electrical and high-temperature parts andrefractory coatings. Zirconium-oxide powder, for flame-sprayedcoatings, comes in either hexagonal or cubic crystal form.Zirconium silicate, ZrSi2, comes as a tetragonal crystal powder. Itsmelting point is about 3000°F (1649°C) and Knoop hardness is about1,000.

Zirconium carbide, ZrC2, is produced by heating zirconia with car-bon at about 3632°F (2000°C). The cubic crystalline powder has a hard-ness of Knoop 2,090 and melting point of 6404°F (3540°C). The powderis used as an abrasive and for hot-pressing into heat-resistant andabrasion-resistant parts. Zirconium oxychloride, ZrOCl2 8H2O, is acream-colored powder soluble in water that is used as a catalyst, in themanufacture of color lakes, and in textile coatings. Zirconium-fusedsalt, used to refine aluminum and magnesium, is zirconium tetra-chloride, a hygroscopic solid with 86% ZrCl4. Zirconium sulfate,Zr(SO4)2 4H2O, comes in fine, white, water-soluble crystals. It is usedin high-temperature lubricants, as a protein precipitant, and for tan-ning to produce white leathers. Soluble zirconium is sodium zirco-nium sulfate, used for the precipitation of proteins, as a stabilizer forpigments, and as an opacifier in paper. Zirconium carbonate is usedin ointments for poison ivy, as the zirconium combines with thehydroxy groups of the urushiol poison and neutralizes it. Zirconiumhydride has been used as a neutron moderator, although the energymoderation may be chiefly from the hydrogen.

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2Structure andPropertiesof Materials

Part

Source: Materials Handbook



Structure and Properties of Materials



The Structure of Matter

Elements, or atoms, are the basic building blocks of all tangiblematerials in the universe. There are 92 natural elements, or materialatoms, almost all of which are stable, from hydrogen, atomic number1, or element 1, to uranium, or element 92. Elements of higher atomicweight than uranium are made, but they are unstable, their timedecay being measured progressively as half-life.

The atom gets its name from the Greek word atomos, meaning indi-visible, and it is not divisible by ordinary chemical means. The ele-ments are used either alone or in combination for making usefulproducts. They combine either as mechanical mixtures or as chemi-cal compounds. In a mixture each element retains its originalnature and energy, and the constituents of the mixture can be sepa-rated by mechanical means. In chemical compounds of two or moreelements, the original elements lose their separate identities; the newsubstance formed has entirely different properties, and the atomicenergy stored within the compound is not equal to the sum of the ele-mental energies. The atoms in chemical compounds are bonded byelectrons. An alloy is usually a combination of chemical compoundsand mixtures, the metal mixtures in the matrix being gaged by theirmaximum fused or liquid solubility, known as the eutectic point.With the elements the number of different compounds, or useful sub-stances, that can be made by varying the combinations of elementsand the proportions is infinite.

The known atoms are arranged progressively in a periodic tableby atomic number, based on the atomic weight of the elementwith hydrogen as the unit of mass, though oxygen may be taken asthe point of calculation. The atom is not a solid, but a region of energyparticles in motion. At various energy levels the geometric shape ofthe electron orbit changes, and the apparent ring, or electron shellstructure, is the energy-level extension of the orbital pattern. The dis-tances and space covered are so vast in relation to the size of the par-ticle, and the speeds are so great, that the interior of the atom mightbe considered mostly empty space. As a single atom is a billion ormore times the size of an electron, it is estimated that if the spacewithin the atom could be removed, a thimbleful of atoms would weighmillions of tons. If the copper atom were magnified 10 billion times,the electrons that the chemist employs to connect it with anotheratom of a molecule would still be too tiny to be seen. Thus, a solidmetal used for construction is a region of relatively vast space popu-lated by energy particles in perpetual motion.

The term space chemistry was first used at the beginning of thetwentieth century by the Dutch physicist van’t Hoff, the founder of

THE STRUCTURE OF MATTER 1069




modern physical chemistry, but the subject was not new. It may besaid that modern atomic science, equipped with advanced experimen-tal methods and testing instruments, has taken up where the Greeks,working only with geometry and the theoretical deductions of meta-physics, left off at their School of Numbers about 450 B.C. The Greeksreasoned that all matter came from one source, made from a qualita-tively indeterminable primordial unit, the monad, now known asenergy. It was stated to be incorporeal, but vital and always inmotion. This idea of a nonmaterial basis of tangible materials, nownecessary for modern scientific analysis of materials, is intrinsic inhuman logic. It came to the Greeks from the Ionians, survivors of theCretan civilization antedating 3000 B.C., and appears in the HebraicGenesis, in the Sanskrit Vedas, and in the Taoism of ancient China.Energy is in harmonic motion, in waves or rays, and may be said tobecome a particle of mass when the frequency is 1, that is, a closedunit cycle. All materials give off light when activated, and light rayshave the fastest known speed, 186,000 mi/s (300,000 m/s).

More than 70 new elements, to element 168, have been projected,though not all have been synthesized. These are higher elementsmade by additions to natural elements. Atoms may also be brokendown by the application of high energy. The process known as fissionis usually by electric energy built up to extremely high voltage by res-onant pulsation in a magnetic field in a manner akin to that of thegeneration of lightning in the clouds. More than 30 subatomic parti-cles have been isolated. Fissionable elements are normally consid-ered to be only those of high atomic weight and radioactivity, andrelative unstability, but all elements are fissionable.

A subatomic unit may be considered as both a wave and a particle.The nucleus of the atom is a relative term. The proton is identicalto the nucleus of the hydrogen atom, and is one unit of positive elec-tricity. The nuclei of all other elements consist of combinations of pro-tons and neutrons. The electrons of the various atoms appear to orbitaround the nucleus, but the electron, though considered a negativelycharged particle, is also a beta ray, and the axis of its vortex motionis in calculable relativity to the respective positron. A detachedpositron has only a momentary existence. In conjunction with an elec-tron, it forms an atomlike structure known as positronium. A spheronmay contain one or more neutrons, and atoms having different num-bers of neutrons are called isotopes and are of different atomicweights and different physical properties.

The helium atom of mass 4, positive charge 2, and zero valencehas two protons and two neutrons, with the protons apparently inopposite polarity. This combination is called an alpha particle.Alpha particles are emitted at high velocity from radioactive ele-

1070 STRUCTURE AND PROPERTIES OF MATERIALS




ments, expelling the detached electrons, and when captured aredeposited as helium. These usually come from outer-ring spheronsand not necessarily from the inner nucleus. The expelled electronsare beta rays. When these collide with a nucleus, high-frequency X-rays break off. Gamma rays are emitted from some radioactiveelements. The difference between X-rays and gamma rays is their ori-gin and wavelength. Gamma rays come from the nucleus; X-rayscome from electrons striking matter. Few of the high-energy X-rayscoming from the sun penetrate the atmosphere.

Gamma rays from the sun come only in infrequent bursts, and thecosmic rays from space are also entirely protons, or stripped ions ofhydrogen. Cosmic rays appear to travel at about the speed of light.Mesons from cosmic rays appear to carry unit charges as beta raysdo, but they have more energy and greater range. While beta rays arestopped in human skin, mesons can cause damage throughout thebody. High-energy cosmic rays are stopped by the atmosphere, andonly a small proportion penetrate to the earth’s surface.

The neutron is a particle of neutral charge with a mass approxi-mately that of a proton. A neutron has a mass 1,838 times that of anelectron, while a proton has a mass 1,836 times that of an electron.High-energy bombardment of nuclei or an individual nucleus yields elec-tron positrons, mesons, and neutrinos. In recent work, these seeminglyfundamental particles have been subdivided into quarks and gluons.

In the technology of producing and processing materials, the atom isnot subdivided, although in some operations of electrochemistry andelectronics the electron is detached, and particles and rays are alsoemployed, especially for activation. With respect to combining ele-ments, metallurgy is high-energy chemistry. In a solid metal, as inother materials, the atom does not appear alone, and the physical prop-erties of a metal or alloy derive chiefly from the molecular structure.

Elements having one, two, or three outside valence electrons aremetals. In chemical reactions they can release these electrons andform positive metal ions. The elements having five, six, or seven outerelectrons are nonmetals. An element with four outer electrons is asemimetal and can react as either a metal or a nonmetal. An ele-ment with eight outer electrons is said to have zero valence and isnormally inactive, but by special energy application, or catalyzation,the linkage of the spherons can be broken and the electrons freed forchemical reactions.

The elements that make up all the planets and the stellar systemsof the universe appear to be the same as those of the earth. There aremany theories for the original formation of the material elements, butthe subject pertains to astronomy rather than to materials technol-ogy, and involves the mathematics of progressive assembly of energy





waves into monoquantic vortices which constitute mass. While ele-ments do not have life in the same sense as the term is used for ani-mals and plants, they do have intrinsic habits that can be controlledand altered by changing the environmental conditions. Elements aregregarious, and atoms separate only when activated by extremes ofenergy, as with high heat, and they tend to congregate even when dis-sipated in water or air.

Elements have orderly, calculable habits of combining into mole-cules, or geometrically shaped units bonded to their own kind or toatoms of other elements. Compounding the elements into useful mate-rials is done by the addition or subtraction of energy with considera-tion of time and space. Even the automatic reactions of two elementsin proximity, known as chemical affinity, and the seeming holdingaction of stabilizing agents depend upon a transfer of energy.

The term crystal is usually applied only to molecular structureswhich at normal temperatures are hard solids that form into pro-nounced geometric shapes or are capable of being split on preciseplanes. Solids without apparent planes are termed amorphous. Butthe crystal shapes tabulated for metals usually represent merely thetypical position pattern of the atoms. Single crystals may be cut fromnatural crystals, grown by flame melting, or grown chemically byapplication of heat and pressure. Seed crystals used to initiategrowth are grains or particles made up of many molecules, while aunit crystal is the unit molecule or, in some cases, the unit pattern ofthe lattice, and these determine the shape and nature of the structure.In microscopy the structures of aluminum and silver appear opticallyas similar cubes, but the unit crystal of aluminum in the solid stateforms both a cube and a lattice, while the unit crystal of silver formsno cube and does not lattice, and the metal grains are cryptocrys-talline. Usually, the smaller the grain size, the nearer the approach tothe physical properties of the single crystal so that large single crys-tals are sometimes made by compacting extremely fine powders.

Quasicrystalline solids are a category of matter intermediatebetween crystals and amorphous materials, such as glasses. Termedquasicrystals, they consist of atoms in ordered arrays, but the pat-terns they form do not recur at precisely regular intervals.

All elements convert progressively from solid to gaseous form by theapplication of energy, usually by heat application, and vice versa by theextraction of heat. The terms solid, liquid, and gas are phase changesdepending on the mobility of the molecule caused by changes in its three-dimensional shape. A gaseous element is one that is a gas at ordinarytemperatures and pressures, such as hydrogen. At extremely low tem-peratures a hydrogen crystal should be a hard, white metal of cryp-tocrystalline structure with straight planes of cleavage. Liquid





hydrogen for rocket fuel normally has a molecule of conical shape inspin. When catalyzed by hot platinum, it changes to an ovaloid shapewhich can pass through a smaller molecular sieve, and it also requires20% less storage space per unit of fuel. These forms are called orthohydrogen and meta hydrogen, but are both H2.

Phase changes often occur within the solid stage, and the change indimensions of the material, called creep, is the effect from change involume of the molecules. With some materials the liquid stage is soshort as to be undetectable, appearing to pass directly from solid tovapor, and this transition is called sublimination. All moleculeshave energy transition points at which they break down to free theoriginal elements or to interact and combine with other available ele-ments to form new compounds. For example, iron molecules, havingfree electrons, disintegrate easily in the presence of air or moisture toform iron oxides. This process is called corrosion; in organic materialsit is called decay. The molecule of gold has no free electrons and,because of its high energy, is not broken down easily by the influenceof other elements. Thus it is said to be noncorrosive. In the case ofaluminum, oxygen from air cross-links the free electrons on the sur-face of the grains and protects the metal from further corrosion.

In metallurgy and the metalworking industries, the elements arenormally not used alone in a pure state, and as solids and liquids onlyin molecular forms. In casting metals and alloys from a melt, the timeof solidification is short, and without the application of high energy, asin the form of high pressure, there is no growth into large single crys-tals. Growth is usually into particles, or grains, which may be singlecrystals or irregular conglomerates of unit crystals. In the contractionof cooling, however, grain boundaries may be so close as to be unde-tectable even at a magnification of 2 million to 1. Thus the impuritiesare likely to be in the unmatched open spaces among the crystals andnot interstitial. But with some latticing molecules, such as copper,there is room within the lattice for smaller atoms or molecules, suchas those of beryllium, without interference with the paths of bondingelectrons. In the aluminum lattice there appears to be no such room.

Organic and other chemicals are usually produced from the ele-ments by synthesis, that is, built up by progressive steps logicallydeduced from known data and theories concerning the natural habitsand characteristics of the atoms and their elementary groups. A com-pound may thus be written as a chemical formula which expressesgraphically the specific number and locations of the atomic elementsin the compound. In some degree this system is also used in the pro-duction of ceramics, i.e., compounds or compound mixtures based onmetallic oxides, where the resultant material is expressed in percent-age proportions of the crystal formulas. Alloys are usually made by





batch-mixing the elements, and the resultant material is expressed inweight percentages of the contained elements, not in terms of themolecular structure on which the physical properties of the alloydepend.


The Natural Elements

AtomicAtomic weight Melting

Name number Symbol O 16.000 point, °C

Actinium 89 Ac 227.028 1430Aluminum 13 Al 26.97 660.0Antimony 51 Sb 121.76 630.5Argon 18 A 39.944 189.3Arsenic 33 As 74.91 814Astatine 85 At …… 470Barium 56 Ba 137.36 704Beryllium 4 Be 9.02 1280Bismuth 83 Bi 209.00 271.3Boron 5 B 10.82 2300Bromine 35 Br 79.916 7.2Cadmium 48 Cd 112.41 320.9Calcium 20 Ca 40.08 850Carbon 6 C 12.00 3700Cerium 58 Ce 140.13 798Cesium 55 Cs 132.91 28Chlorine 17 Cl 35.457 101Chromium 24 Cr 52.01 1800Cobalt 27 Co 58.94 1490Columbium (niobium) 41 Cb 92.91 2000Copper 29 Cu 63.57 1083.0Dysprosium 66 Dy 162.46 1412Erbium 68 Er 167.64 1529Europium 63 Eu 152.0 822Fluorine 9 Fl 19.00 223Francium 87 Fr 223 ……Gadolinium 64 Gd 157.3 1312Gallium 31 Ga 69.72 29.78Germanium 32 Ge 72.60 958Gold 79 Au 197.2 1063.0Hafnium 72 Hf 178.6 1700Helium 2 He 4.002 271.4Holmium 67 Ho 163.5 1474Hydrogen 1 H 1.0078 259.2Illinium (promethium) 61 Il (Pm) 147.0Indium 49 In 114.76 156.4Iodine 53 I 126.92 114Iridium 77 Ir 192.9 2447Iron 26 Fe 55.84 1535Krypton 36 Kr 83.7 157Lanthanum 57 La 138.92 826Lead 82 Pb 207.22 327.4Lithium 3 Li 6.940 186Lutetium 71 Lu 175.0 1663





The Natural Elements (Continued)

AtomicAtomic weight Melting

Name number Symbol O 16.000 point, °C

Magnesium 12 Mg 24.32 650Manganese 25 Mn 54.93 1260Mercury 80 Hg 200.61 38.87Molybdenum 42 Mo 96.0 2625Neodymium 60 Nd 144.27 840Neon 10 Ne 20.183 248.6Nickel 28 Ni 58.69 1455Nitrogen 7 N 14.008 210.0Osmium 76 Os 191.5 2700Oxygen 8 O 16.0000 218.8Palladium 46 Pd 106.7 1554Phosphorous 15 P 31.02 44.1Platinum 78 Pt 195.23 1773.5Polonium 84 Po …… 1800Potassium 19 K 39.096 63Praseodymium 59 Pr 140.92 940Protoactinium 91 Pa 231Radium 88 Ra 226.05 700Radon 86 Rn 222 71Rhenium 75 Re 186.31 3000Rhodium 45 Rh 102.91 1966Rubidium 37 Rb 84.44 39Ruthenium 44 Ru 101.7 2450Samarium 62 Sm 105.43 1300Scandium 21 Sc 45.10 1200Selenium 34 Se 78.96 220Silicon 14 Si 28.06 1430Silver 47 Ag 107.880 960.5Sodium 11 Na 22.997 97.7Strontium 38 Sr 87.63 770Sulfur 16 S 32.06 119.2Tantalum 73 Ta 180.88 3000Technetium 43 Ma 97.8 2300Tellurium 52 Te 127.61 450Terbium 65 Tb 158.9 1356Thallium 81 Tl 204.39 300Thorium 90 Th 232.12 1700Thulium 69 Tm 169.4 1545Tin 50 Sn 118.70 231.9Titanium 22 Ti 47.90 1820Tungsten 74 W 184.0 3410Uranium 92 U 238.14 1850Vanadium 23 V 50.95 1735Xenon 54 Xe 131.3 112Ytterbium 70 Yb 173.04 1500Yttrium 39 Y 88.92 1490Zinc 30 Zn 65.38 419.5Zirconium 40 Zr 91.22 1700





Specific Gravity and Density of Materials

Specific gravity Density, lb/ft3 Density, kg/m3

Aluminum 2.7 165 2,643Beryllium 1.85 115.5 1,850Bronze 8.0 509 8,154Cadmium 8.6 537 8,603Cast iron 7.2 450 7,209Cobalt 8.76 547 8,763Columbium 8.57 535 8,571Copper 8.9 556 8,907Glass 2.5 160 2,563Gold 19.32 1206 19,320Lead 11.38 710 11,374Magnesium 1.74 109 1,746Mercury 13.6 849 13,601Molybdenum 10.2 637 10,205Nickel 8.9 556 8,907Nylon 1.14 71.2 1,141Osmium 22.58 1410 22,697Palladium 12.10 755 12,095Platinum 21.45 1339 21,450Polyethylene 0.91 to 0.965 56.8 to 60.2 910 to 960Polystyrene 0.906 56.6 907Rhodium 12.44 777 12,448Steel 7.8 490 7,850Zinc 7.5 440 7,049Silver 10.7 668 10,701Titanium 4.5 281 4,501Tantalum 16.6 1036 16,597Tungsten 19.6 1224 19,608Uranium 18.7 1167 18,702Zirconium 6.5 406 6,504Ash, dry 0.63 40 641Cedar, dry 0.36 22 352Fir, dry 0.56 32 513Maple, dry 0.65 43 689Redwood, dry 0.42 26 417White pine, dry 0.41 26 417Granite 2.6 165 2,643Limestone 2.5 165 2,643Sandstone 1.8 110 1,762Pressed brick 2.2 140 2,243Common brick 1.9 120 1,922Terra cotta 1.9 120 1,922Concrete 2.3 144 2,307Portland cement 3.0 183 2,932Mortar 1.7 103 1,650Earth, dry, loose 76 1,218Earth, dry, packed 95 1,522Sand and gravel 60 961Asbestos 153 2,451Lithium 0.533 33.28 533Marble 2.7 170 2,723Shale 92 1,474Tar 1.2 75 1,202Bluestone 2.5 159 2,547




Waves and Colors as Material Elements

Electromagnetic radiations

Tangible materials and radiations have a common energy origin,and thus bear a cosmic relation, but radiation is not matter in theordinary sense of the term. Radiation is caused by vibrations, and ischaracterized by wavelengths rather than mass as is ordinary matter.Waves of high frequency and short wavelength result from the vibra-tion of extremely small particles, such as electrons of the materialatom, while those of low frequency and long wavelength arise fromslow vibrations, such as those from a coil in a magnetic field.

Radiations are produced when materials are broken down orchanged to another form, and there is then an actual loss of massequal to the amount of energy emitted. In reverse, matter is producedwhen energy in the form of radiation is directed upon matter, and anactual increase in the mass of the matter results. All materials innature are being constantly bombarded with various radiations, but itrequires such an extremely large amount of energy to produce themost minute quantities of matter that the continuous changes inmost materials are not noticeable in any historic period of time.

The spectrum of electromagnetic radiations extends from wave-lengths of many hundred-millionths of a centimeter, or infinitelysmall, to wavelengths of many kilometers, or infinitely large. Thevelocity of these waves is the same for all lengths of wave, 186,000mi/s (300,000 km/s). In the spectrum, the light waves which makeobjects visible to the human eye form only a small part. The humaneye can see through only such materials as these light waves will pen-etrate. But electrical eyes can be made to operate in other wave-lengths and record vision not seen by the human eye. Not all animalssee with the same wavelengths, and some animals do not have nor-mal eyes but receive vibrations through special receiving parts of thebody. Different materials transmit, absorb, or reflect radiations differ-ently. Quartz and glass, normally called transparent, transmit only asmall band of light and heat waves, but will not pass very short radia-tions. By changing the composition of the glass the heat waves can beblocked, or some of the very short waves can be passed through. Somematerials, like lead, will block the very short waves, and can be usedfor X-ray shields. Other materials, like beryllium, will pass only veryshort waves, and can be used for selective windows.

Silver will reflect 90% of visible light, while tin reflects only 70%,but silver loses reflectivity in sulfur atmospheres. Gold reflects only61% of visible light, but has high reflectivity of infrared rays, usefulfor electronic purposes. All materials are sensitive to particular lightwaves and emit electrons when struck by those waves. Zinc is sensi-

WAVES AND COLORS AS MATERIAL ELEMENTS 1077




tive to very short ultraviolet light; cesium is sensitive to green light;potassium is sensitive to blue light. This property is the basis of elec-tronic color selectors. It is also the basis for the operation of photo-electric cells, in which the liberated electrons constitute an electriccurrent. Such cells are widely used as automatic switches and forelectronic conversion of light intensities to sound waves.





WAVES AND COLORS AS MATERIAL ELEMENTS 1079

Element colors at incandescence

Flame colorations caused by heating materials to incandescence indi-cate the presence of certain elements, as the light from each elementin burning has a predominance of rays or wavelengths that are char-acteristic of that particular element. Some elements, such as sodium,show a distinct bright color because of a predominance of wave-lengths within that color range in the visible spectrum, while othersshow pale or intermediate colors difficult to distinguish, usuallybecause the rays have no predominating wavelength within the visi-

Predominant Flame Colors of Materials

Element Color Element Color

Lithium Deep red Antimony Blue-greenStrontium Crimson Copper Green-blueCalcium Yellow-red Arsenic Light blueSodium Bright yellow Lead Light blueBarium Yellow-green Selenium BlueMolybdenum Green-yellow Indium Deep blueZinc Light green Potassium Purple-redBoron Green Rubidium VioletTellurium Deep green Cesium Bluish purpleThallium Greenish blue

Reflecting Powers of Various Metal Surfaces

White light directly Colorreflected, percent Silver 0

Silver 90 0Chromium 61 Blue-green 12 unitsNickel 50 Red 16 unitsStainless steel 49 Blue-green 3 unitsWhite bronze speculum 70 Red 1 unit

Reflecting Power of Various Colors in Paints

Light reflection, Light reflection,Color percent Color percent

Flat white 85–89 Sky blue 58Bone white 69–70 Light orchid 57Canary yellow 68–72 Buff 47Light ivory 70 Pea green 40Aluminum 70 Tan 34Cream 65–69 Peacock blue 34Light green 66 Steel gray 30Ivory 61–63 Brown 9Peach 58–59




ble spectrum but are mixtures of many wavelengths. Other elements,such as iron, have a predominance of rays that are not in the visibleband, with wavelengths shorter or longer than those visible to theeye. Flame coloration is used in metallurgical laboratories to deter-mine the content of alloys by burning small pieces and studying thelight with a refractive prism. This property of the elements is also uti-lized in making carbon electrodes for electric-arc lights to give the fullwhite light of sunshine, or short waves for therapy or industrial use,or long wavelengths for heat. For example, carbon alone gives a pre-dominance of short wavelengths with the visible rays predominantlyon the red side of the spectrum. When cerium metals are blendedwith the carbon, the visible light is balanced with the blue-violet togive a more even, white light. When the carbon is blended with iron,nickel, and aluminum, which are all on the low-wavelength side ofthe spectrum, lower-zone ultraviolet rays are obtained.

Terms used in material color designation

Hue is the predominant light wavelength reflected by the coloringmaterial, and it determines the color designation.

Brightness, or value, is the percentage of light reflected. A bril-liant white approaches 100% and a jet black approaches 0%. Black isthe absence of light waves; white is a combination of all the variouswavelengths. White light is broken down by refraction into separatewave bands, or hues, as in the natural rainbow. Chroma refers to theintensity of a color. Tint refers to color modified toward white,shade to one toward black.

The color circle is composed of 12 colors spaced at equal intervals:yellow, orange, red, violet, blue, green, etc., with intermediatesbetween each. Pigment colors are obtained usually by subtractivemixing; for example, when blue and yellow are mixed, the blueabsorbs the red, orange, and yellow rays, and the yellow absorbs theblue and violet rays, and so the resulting color is green.

Under proper illumination it is possible to detect with the eyeexceedingly slight color differences, the number of distinguishable col-ors being estimated, by the U.S. Bureau of Standards, at 10,000,000.

Colors or hues vary slightly with different batches of paints, dyes,etc. For this reason products that must be matched exactly in hue areusually finished from the same batch or lot. Color matching of metalsis also often important. For example, for installation of kitchens orother building equipment the stainless steel should preferably befrom one lot since the color shades vary with the proportions ofchromium, nickel, or manganese. These are “white” metals, butchromium has a blue tone, nickel has a yellow tone, and manganese





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has a purple tone. Welding alloys and solders are also matched to thecolor of the base metal by varying the proportions of metals with dif-ferent tints.

Visibility at a distance varies with different colors. Red can be seenand recognized at long distances while blue can be seen at only shortdistances. The order of visibility of colors at a distance is red, green,white, yellow, blue. The legibility of a color, however, also varies withthe background. Black on yellow is more legible than black on white,whereas green, red, or blue on white is more legible than black onwhite. Visibility and legibility are important in signs, packages, orproducts that must be distinguished easily.


Metal melting range and color scale. (Chart from the Linde Air Products Co.)




Harmony of color or tone design is a complicated art. It com-prises the color relationship to convey pleasing emotional reaction,and includes various terms. A rich color is a hue at its fullest inten-sity. A warm color is one in which the red-orange predominates. Acool color is one in which the blue-green predominates. In general,warm colors are pleasing or exciting, while cool colors are not sopleasing or are restful to the senses. A receding color is one givingthe illusion of withdrawing into distance by a gradation towardanother tone or hue. Color, from the standpoint of harmony anddesign, is a sensation effect. It is not inherent in the pigments, dyes,or other materials, but is the sensation effect from those light raysreflected to the eye by the material.

Property of Flavor in Materials

The quality of many materials is judged by the flavor. Flavor is theresultant of three senses: taste, smell, and feeling. Some materials,such as salt and quinine, may be detected by taste alone. Some, suchas coffee and butter, depend largely upon smell. Flower perfumes aredetected by smell alone. The flavor of fruits depends upon both tasteand smell, and without smell it would be only sour or sweet. Pepperhas little or no taste, but is detected by the aroma and by the sense offeeling.

The four standard components of taste are: sweet, sour, salt, andbitter. Taste buds are located in the tongue. The tip, back, and edgesof the tongue can detect all four sensations, but the center of thetongue can detect only a sour taste, and the surrounding area candetect only salty and sour. Sour taste is caused by hydrogen ions,and salty taste is due to cations from the alkali metals, accentedwhen anions from the halogens are present. Sweetness and bitter-ness may or may not be from ions, and the stimuli are more complex.But all taste is electrochemical, translated to the nerves as sensa-tions. Some materials when injected into the blood can be tastedwhen the blood reaches the tongue.

Odor detection is electrochemical but not entirely so, since mole-cules which have the same shape may have the same odor though beunrelated chemically. The sense of smell is due to oscillations of thevalence electrons in the molecules of the substance. The molecules ofsubstances inhaled stimulate the tiny olfactory hairs high in thenasal cavity, and the effect is translated to the nerves as impressionsor sensations. The sense of taste usually requires considerable mater-ial to register the sensation, but only the most minute molecularqualities are required to register smell. A normal person can detect avast variety of odors, but for convenience the four fundamental odors

PROPERTY OF FLAVOR IN MATERIALS 1083




have been designated as fragrant, acid, burnt, and caprylic. A mater-ial is then designated with a four-digit number to indicate the degreeof each odor, each odor thus having 10 degrees or variations, thusgiven 9,999 variants. Various materials are taken as standards forthe numbers, or 40 standards. The sense of smell is so discriminatingthat it can detect separate odors in highly complicated mixtures. Mostodors are mixtures, and the art involved in the perfumery industry isto form harmonies that give a resultant pleasant sensation.

Flavors that affect the touch sensation are described as pungent,sharp, acrid, and cool. These are caused by actual pain as the bitingof an acid or the cooling effect of deoxidation. Greasiness and oili-ness are sensations of feel that affect taste but are not a part of it.Texture also is a feeling sense and not a part of flavor. The sensationof puckery of the tannin of some fruits is a definite constriction ofmembrane and is not taste. All of these have an effect upon the desir-ability of the material as a food, but in a manner apart from flavor.Too much sweetness, sourness, or saltiness will clog the taste buds,and they must be then rested before a true flavor can be detected, butthe recovery is rapid. Temperature also has an effect, and true flavorsare detected only at about the temperature of the body. The judgmentand grading of coffee, tea, butter, etc., are done solely by the senses ofexperts in comparison with standards.

Fundamentals of Biotic Materials

The biotics constitute an extensive group of organic materials thatare actual living microorganisms and cannot be expressed as chemi-cal formulas. All of these minute bits of living matter are of plant andanimal origin and may be considered as chemical factories. It is thechemicals that certain species secrete under certain conditions thatmake them industrially and medicinally useful. The chemical secre-tions are enzymatic and catalytic in character and thus enable vari-ous chemicals to react on contact. In industry they are used aschemical activating agents, as ferments, as leavening agents, and invarious processing. In medicine they are known as antibiotics andare used to destroy the biotics, or bacteria, of diseases which locatethemselves in the human body.

Biotics are found everywhere in myriad quantities. A cubic centime-ter of raw earth may contain as many as 50,000 fungi, or micro-phytes, 500 million bacteria, and 250 million actinomycetes, thelatter being living organisms that may be ascribed, with reservations,to either the plant or the animal kingdom, and are distinguished bytheir mass of long, silky filaments. All these organisms lead a jungle-like existence, attacking everything, decomposing plant debris to





make humus, liberating nitrogen from proteins, liberating oxygenfrom rocks, liberating carbon dioxide and water from organic acids inplants and soil, and also preying on one another as jungle animals do.Without these organisms the life cycles of all living things could not bemaintained. This same teeming population also furnishes the individ-ual types of organisms that aid humanity in medicine and industry.

The number of species of these microorganisms is innumerable.Each species has at least one enemy species that it destroys on con-tact or by which it is itself destroyed. Each apparently has a certaindefinite range of activity, beyond the bounds of which it is useless.Where one biotic is used in the manufacture of a certain product, asimilar but different species used under the same conditions producesan entirely different product, or may affect the quantitative yield ofthe product desired. The formation of ethyl alcohol by the fermenta-tion of starch or sugar is caused by a biotic which is then itself killedwhen the alcohol produced has arrived at a certain concentration.Other biotics may be killed by the heat that their own work produces,as at the “crisis” point of certain fevers. In general, biotics can with-stand excessive cold but are usually killed by relatively low heats.

Besides the use of biotics for the medicinal and industrial applica-tions that are now known, there are believed to be enormous possibili-ties for their use in large-scale chemical processing in the future. Butthe isolation of microorganisms is tedious laboratory work involvingthe extraction of a pure strain from cultures containing many species,and once separated, the proper conditions to promote rapid multipli-cation must be discovered. Even at this stage, a biotic found to be use-ful in the manufacture of a certain product may simultaneouslymanufacture another unwanted product, difficult and costly to sepa-rate from the desired one. But from each biotic some kind of chemicalis secreted, and that chemical is the ultimate end of biotic research.

Units of Measure

Useful conversion factors

1 acre 43,560 square feet 0.40469 hectare

1 nanometer 0.001 micrometer 0.03937 millionths of an inch

1 ardeb (Egypt) 5.44 bushels

1 arshin (Russia) 28 inches

1 barrel (U.S.), cement 376 pounds

1 barrel, oils 42 gallons

1 berkovets (Russia) 361.13 pounds

UNITS OF MEASURE 1085




1 board foot 144 cubic inches

1 bolt, cloth 40 yards 36.576 meters

1 buncal (Indonesia) 1.49 troy ounces

1 bushel 2,150.4 cubic inches

1 bushel, imperial (British) 1.0315 U.S. bushels

1 candy (India) 784 pounds

1 carat, metric 0.200 gram

1 carat (U.S.) 0.2056 gram

1 chittak (India) 900 grains

1 circular mill 0.0000007845 square inch

1 cuarteron (Spain), oil 0.133 liquid quart

1 cuartillo (Mexico), liquid 0.482 liquid quart

1 cubic foot 1,728 cubic inches

1 cuffisco (Sicily), oil 5.6 gallons

1 dram 1.7718 grams

1 dinero (Spain) 18.5 grains

1 drachma (Turkey) 49.5 grains

1 ell 48 inches

1 feddan (Egypt) 1.038 acres

1 firkin 9 U.S. gallons 34.068 liters

1 flask, mercury 75 pounds 34.02 kilograms

1 foot 12 inches 0.3048 meter

1 gallon 231 cubic inches

1 gallon, imperial (British) 1.20094 U.S. gallons

1 gallon, proof (British) 1.37 U.S. proof gallons

1 gill 0.25 pint 0.118292 liter

1 grain 0.06480 gram

1 gram 15.43 grains 0.03527 avoirdupois ounce

1 gram (Libya) 165.3 pounds

1 hamlah (Egypt) 165.1 pounds

1 hectare 2.471044 acres

1 hogshead 63 U.S. gallons

1 hundred weight (British) 112 pounds





1 inch 0.0833 foot 2.54005 centimeters

1 iron, leather thickness measure 1⁄48 inch

1 kantar (Egypt) 99.034 pounds

1 keel (British), coal 21.2 long tons

1 kilogram 2.205 pounds

1 koku (Japan) 47.65 gallons 5.119 bushels

1 kun (Korea) 1.323 pounds

1 kwan (Japan) 1,000 momme 8.267 pounds

1 ligne, metal button measure 1⁄40 inch

1 liter 1.057 liquid quarts

1 lug (Bahamas) 30 pounds avoirdupois

1 meter, square 1.196 square yards

1 mil, square 0.000001 square inch

1 micrometer 0.001 millimeter 0.00003937 inch

1 mil 0.001 inch 0.0254 millimeter

1 mile 5,280 feet 1.69035 kilometers

1 mile, square 640 acres

1 millimeter 0.03937 inch

1 ounce, avoirdupois 28.35 grams 0.0625 pound

1 ounce, troy 31.1 grams

1 peck 0.25 bushel 8.8096 liters

1 perch 1 square rod 30.25 square yards

1 picul (China) 100 catties 133.33 pounds

1 picul (Indonesia) 136.2 pounds

1 picul (Japan) 132.3 pounds

1 pint, dry measure 33.6 cubic inches

1 pint, liquid measure 28.875 cubic inches

1 pood (Russia) 36.11 pounds

1 pound, avoirdupois 16 ounces 7,000 grains 0.4536 kilogram

1 pound, troy 12 ounces 0.37324 kilogram

1 pound, Venetian 1.058 avoirdupois pounds

1 quart, dry measure 2 pints, dry 1.1012 liters

1 quart, liquid 57.749 cubic inches 0.9463 liter





1 quintal (British) 112 pounds

1 quintal, metric 110 kilograms 220.5 pounds

1 ream, paper measure 500 sheets 20 quires

1 rod 5.5 yards

1 scruple, apothecary weight 20 gains 1.296 grams

1 shih tan (China) 50 kilograms 110.231 pounds

1 standard (British), timber 1,980 board feet

1 standard (U.S.), timber 16.67 cubic feet

1 tank (India), gemstones and pearls 24 rati 0.145 ounce

1 tierce, thin-staved cask 42 gallons 310 to 370 pounds

1 ton, long 2,240 pounds 1,016.047 kilograms

1 ton, metric 1,000 kilograms 0.9842 long ton 1.102 short tons

1 ton, short 2,000 pounds 0.8929 long ton

1 vedro (Russia) 3,249 gallons

1 yard = 3 feet 0.9144 meter


Metric Length Measurements

Unit Inches Feet Millimeters Centimeters Meters

One inch 1 0.0833 25.4 2.54 0.0254One foot 12 1 304.8 30.48 0.3048One millimeter 0.03937 0.00328 1 0.1 0.001One centimeter 0.3937 0.0328 10 1 0.01One meter 39.37 3.2809 1,000 100 1One yard 36 3 914.4 91.44 0.9144

Standard Paper Sizes

Folio note 5.5 by 8.5 in (14.0 by 21.5 cm)Pocket note 6 by 9.5 in (15.2 by 24.1 cm)U.S. government writing 8 by 10.5 in (20.3 by 26.7 cm)Commercial writing 8.5 by 11 in (21.6 by 27.9 cm)Legal cap 8.5 by 14 in (21.6 by 35.6 cm)Foolscap 12 by 16 in (30.5 by 40.6 cm)Denny 16 by 21 in (40.6 by 53.3 cm)Folio 17 by 22 in (43.2 by 55.9 cm)Royal 19 by 24 in (48.3 by 70.0 cm)Super royal 20 by 28 in (50.8 by 71.2 cm)Elephant 23 by 28 in (58.4 by 71.2 cm)Imperial 23 by 31 in (58.4 by 78.7 cm)





Temperature Conversion Scale

To change a temperature in degrees Celsius to degrees Fahrenheit, multiply by 9⁄5 and add32, thus F 9⁄5 (C) 32. To change degrees Fahrenheit to degrees Celsius, subtract 32and multiply by 5⁄9, thus, C 5⁄9 (F 32).

°C °F °C °F °C °F °C °F °C °F

0 32 230 446 460 860 690 1274 920 16885 41 235 455 465 869 695 1283 925 1697

10 50 240 464 470 878 700 1292 930 170615 59 245 473 475 887 705 1301 935 171520 68 250 482 480 896 710 1310 940 172425 77 255 491 485 905 715 1319 945 173330 86 260 500 490 914 720 1328 950 174235 95 265 509 495 923 725 1337 955 175140 104 270 518 500 932 730 1346 960 176045 113 275 527 505 941 735 1355 965 176950 122 280 536 510 950 740 1364 970 177855 131 285 545 515 959 745 1373 975 178760 140 290 554 520 968 750 1382 980 179665 149 295 563 525 977 755 1391 985 180570 158 300 572 530 986 760 1400 990 181475 167 305 581 535 995 765 1409 995 182380 176 310 590 540 1004 770 1418 1000 183285 185 315 599 545 1013 775 1427 1005 184190 194 320 608 550 1022 780 1436 1010 185095 203 325 617 555 1031 785 1445 1015 1859

100 212 330 626 560 1040 790 1454 1020 1868105 221 335 635 565 1049 795 1463 1025 1877110 230 340 644 570 1058 800 1472 1030 1886115 239 345 653 575 1067 805 1481 1035 1895120 248 350 662 580 1076 810 1490 1040 1904125 257 355 671 585 1085 815 1499 1045 1913130 266 360 680 590 1094 820 1508 1050 1922135 275 365 689 595 1103 825 1517 1055 1931140 284 370 698 600 1112 830 1526 1060 1940145 293 375 707 605 1121 835 1535 1065 1949150 302 380 716 610 1130 840 1544 1070 1958155 311 385 725 615 1139 845 1553 1075 1967160 320 390 734 620 1148 850 1562 1080 1976165 329 395 743 625 1157 855 1571 1085 1985170 338 400 752 630 1166 860 1580 1090 1994175 347 405 761 635 1175 865 1589 1095 2003180 356 410 770 640 1184 870 1598 1100 2012185 365 415 779 645 1193 875 1607 1105 2021190 374 420 788 650 1202 880 1616 1110 2030195 383 425 797 655 1211 885 1625 1115 2039200 392 430 806 660 1220 890 1634 1120 2048205 401 435 815 665 1229 895 1643 1125 2057210 410 440 824 670 1238 900 1652 1130 2066215 419 445 833 675 1247 905 1661 1135 2075220 428 450 842 680 1256 910 1670 1140 2084225 437 455 851 685 1265 915 1679 1145 2093




Hardness numbers

The Brinell method of determining hardness is by the indentationeffect of a hard ball pressed into the surface of the metal to be tested.Tables of hardness numbers corresponding to the various indentationmeasurements are furnished by the makers.

The Scleroscope, or “Shore,” method measures hardness by a com-parison of the effect of the drop and rebound of a diamond-tippedhammer dropped from a fixed height. The resulting rebound is thenread on a graduated scale.

The Rockwell hardness tester measures hardness by determiningthe depth of penetration under load of a steel ball or diamond cone inthe material being tested. Rockwell hardness is expressed as a num-ber, which is read on a graduated gage.

The Mohs hardness scale for abrasives and minerals is measuredby scratch comparison, the mineral talc being taken as 1 and the dia-mond as 10 on the scale. This method is only an approximation formineral comparison, and the Knoop indentor is used for measuringcomparative hardness of hard materials.

The Vickers method is similar to the Brinell and Rockwell methodsexcept that a diamond in the form of a pyramid is used as the pene-trator. It is thus suitable for measuring metals of high hardness.

The Bierbaum microcharacter, or Bierbaum number, is used todetermine the hardness by scratch. The width of a scratch made bydrawing the point of a cube-shaped diamond across the surface undera 3-g load is measured with a microscope and determines the degreeof hardness.

Index of refraction

Index of refraction indicates the relative amount of light transmittedby a material. As the index of refraction increases, the transmittedlight decreases. The amount of light reflected may be considered as ininverse proportion to the amount transmitted, though much of thelight may be dissipated. A vacuum transmits 100% of the light andreflects 0%, and has a refractive index of 1.00. A polished diamondwith parallel sides will transmit only 83% of the light, and thereflected light makes the diamond shine. The sparkle of angle-cut dia-monds and highly refractive cut glass is caused by the dissipated ordeflected light emerging from the angles.

Acidity and alkalinity scale

The degree of acidity or alkalinity of solutions is expressed by the pHvalue. Water is considered neutral and is given a pH value of 7.Values below 7 are acid, each declining value being 10 times moreacid than the previous value. A pH of 6 is 10 times more acid than a






Approximate Relationship of Vickers, Shore (Scleroscope), Rockwell, and BrinellHardness Numbers

Vickers Approximate tensileor Shore or Rockwell strength of Hardness Firth Scleroscope C B Brinell steels, lb/in2 MPa class of steel

1,220 96 68 … 7801,114 94 67 … 7451,021 92 65 … 712

329,000 to 380,000

940 89 63 … 682(2,268 to 2,620) Hard to file

867 86 62 … 653803 84 60 … 627746 81 58 … 601694 78 56 … 578649 75 55 … 555608 73 53 … 534587 71 51 … 514551 68 50 … 495534 66 48 … 477 165,000 to 317,000 Machining opera-502 64 47 … 461 (1,138 to 2,186) tions difficult474 62 46 … 444460 60 44 … 429435 58 43 … 415423 56 42 … 401401 54 41 … 388390 52 39 … 375380 51 38 … 363361 49 37 … 352344 48 36 … 341335 46 35 … 331320 45 34 … 321312 43 32 … 311305 42 31 … 302291 41 30 … 293285 40 29 … 285278 38 28 … 277272 37 27 … 269261 36 26 … 262255 35 25 … 255250 34 24 100 248 78,000 to 159,000 Commercial 240 33 23 99 241 (538 to 1,096) machining range235 32 22 99 235226 32 21 98 229221 31 20 97 223217 30 18 96 217213 30 17 95 212209 29 16 95 207197 28 14 93 197186 27 12 91 187177 25 10 89 179171 24 8 87 170154 23 4 83 156144 21 0 79 143




pH of 7, and a pH of 3 is 10,000 times more acid than a pH of 7.Solutions having values from 7 to 14 are alkaline by the same multi-ples of 10. A pH of 14 is 10 million times more alkaline than a pH of 7.Chemical indicators used to indicate the acidity or alkalinity of solu-tions are shown in the acidity-alkalinity table.

Viscosity of liquids

The viscosity of a liquid is its resistance to change in its form, orflow, caused by the internal friction of its particle components. Thus,the higher the viscosity, the less fluid it is. When a liquid is hot, thereis less internal friction owing to the greater mobility and distancebetween the molecules, and a liquid will flow more readily than whenit is cold. Thus, all the comparisons of viscosity should be at the sametemperature. Kinematic viscosity is the ratio of viscosity to density.Specific viscosity is the ratio of the viscosity of any liquid to that of


Index of Refraction

Material Index Material Index

Diamond 2.42 Nylon 1.53Ruby 1.80 Polyethylene 1.52Sapphire (synthetic) 1.77 Pyrex (borosilicate glass) 1.52Iceland spar 1.66 Window glass (soda-lime) 1.52Flint glass (dense leaded) 1.66 Acrylic 1.50Flint glass (dense barium) 1.62 Cellulose acetate 1.48Vinylidene chloride 1.61 Cellulose acetate butyrate 1.47Polystyrene 1.59 Ethyl cellulose 1.47Flint glass (light leaded) 1.58 Fused quartz 1.46Flint glass (light barium) 1.57 Water 1.33Amber 1.55 Ice 1.30Quartz crystal 1.54 Air 1.0003Urea-formaldehyde 1.54 Vacuum 1.00

Acidity-Alkalinity Indicators

pH range

Meta cresol purple 1.2–2.8 Red to yellowThymol blue 1.2–2.8 Red to yellowBromophenol blue 3.0–4.6 Yellow to blueBromocresol green 4.0–5.6 Yellow to blueChlorophenol red 5.2–6.8 Yellow to redBromothymol blue 6.0–7.6 Yellow to bluePhenol red 6.8–8.4 Yellow to redCresol red 7.2–8.8 Yellow to redThymol blue 8.0–9.6 Red to blue





water at the same temperature. The reciprocal of viscosity is calledfluidity. Viscosity is usually expressed in poises or centipoises, apoise being equal to 1 g/(cm s).

The specific gravity of a liquid is the relative weight per unit vol-ume of the liquid compared with the weight per unit volume of purewater. Water is arbitrarily assigned the value of 1.000 g/cm3. All liq-uids heavier than water thus have specific gravities greater than1.000; liquids lighter than water have values less than 1.000. Usually,the specific gravity of a liquid is measured at 15°C or at room temper-ature. In practice, measurements are taken with a series of weightedand graduated glass cylinders called hydrometers. These float verti-cally, and the markings are usually in degrees Baumé.

Color determination of lubricating oils

Color determination of lubricating oils and petroleum is made by com-parison with standard colored disks. Light is dispersed through a 4-oz(0.1-kg) sample bottle of the oil to be tested, and the color is comparedvisually with the gelatin colors on the glass. The colors on the stan-dard glass disks of the National Petroleum Association are as follows:

1 Lily white 4 Orange pale1.5 Cream white 4.5 Pale2 Extra pale 5 Light red2.5 Extra lemon pale 6 Dark red3 Lemon pale 7 Claret red3.5 Extra orange pale

Gasoline and fuel oil rating

The cetane number of a diesel fuel is numerically equal to the per-centage by volume of cetane in a mixture of cetane and a-methyl-naphthalene which will match the fuel in ignition quality. Cetane hasthe composition CH3(CH2)14CH3, and a-methylnaphthalene CH3 C10H7. The cetane number of a fuel is given as the nearest whole

Liquid Viscosity, cp Liquid Viscosity, cp

Benzene (0°C) 0.906 Linseed oil (30°C) 33.1Carbon tetrachloride (0°C) 1.35 Soybean oil (30°C) 40.6Mercury (0°C) 1.68 Sperm oil (15°C) 42.0Ethyl alcohol (0°C) 1.71 Sulfuric acid (0°C) 48.4Water (0°C) 1.79 Castor oil (10°C) 2,420Phenol (18°C) 12.7 Rape oil (0°C) 2,530




number. Thus, if it required 49.8% of cetane in the mixture to match,the number would be 50.

The octane number of a fuel is the whole number nearest to thepercentage by volume of isooctane, (CH3)3C:CH2CH(CH3)2, in a blendof isooctane and normal heptane, CH3(CH2)5CH3, that the fuelmatches in knock characteristics.

Phenol coefficient

Phenol is used as the standard for measuring the bacteria-killingpower of all other disinfectants, and the relative bacteria-killingpower is expressed as the phenol coefficient.

The phenol coefficient is the ratio of the dilution required to kill theHopkins strain of typhoid bacillus in a specified time compared withthe dilution of phenol required for the same organism in the sametime. Usually, 2.5- and 15-minute time limits are used, and the coeffi-cient is calculated from the average of the two. For example, if 1:80and 1:110 dilutions of phenol kill in 2.5 and 15 minutes, respectively,as the necessary dilutions of the disinfectant under test are 1:375 and1:650, then the phenol coefficient of the disinfectant is 5.3.

Physical and Mechanical Properties

Definitions of physical and chemical properties

Acid number. The weight in milligrams of potassium hydroxide required toneutralize the fatty acid in 1 g of fat or fatty oil.

Aliphatic. Having a straight, chainlike molecular structure.

Anhydrous. Having no water of crystallization in the molecule. A hydratedcompound contains water of crystallization which can be driven off by heat-ing.

Aromatic. Having a ringlike molecular structure.

Brittleness. The property of breaking without perceptible warning or with-out visible deformation.

Bursting strength. The measure of the ability of a material, usually in sheetform, to withstand hydrostatic pressure without rupture.

Compressibility. The extent to which a material, such as for gaskets, iscompressed by a specified load. Permanent set is the unit amount, in per-cent, that the material fails to return to the original thickness when the loadis removed. Recovery is the amount, in percent, of the return to originalthickness in a given time, and is usually less under a prolonged load.

Conductivity. The rate at which a material conducts heat or electricity.Silver is the standard of reference, as it is the best of the known conductors.

Creep rate. The rate at which strain, or deformation, occurs in a material





under stress or load. Creep strength is the maximum tensile or compressivestrength that can be sustained by a material for a specified strain and time ata specified temperature. Creep recovery is a measure, in percent, of thedecrease in strain, or deformation, when the load is removed.

Ductility. The ability of a material to be permanently deformed by tensionwithout rupture.

Elasticity. The ability of a material to resume its original form after removalof the load which has produced a change in form. A substance is highly elasticif it is easily deformed and quickly recovers.

Elastic limit. The greatest unit stress that a material is capable of with-standing without permanent deformation.

Elongation. The increase in length of a bar or section under load, expressedas a percentage difference between the original length and the length at themoment of rupture or at a specific strain.

Factor of safety. The ratio of the ultimate strength of a material to its work-ing stress.

Fatigue strength. The measure in pounds per square inch (megapascals) ofthe load-carrying ability without failure of a material subjected to a loadingrepeated a definite number of times. Fatigue strength is usually higher thanthe prolonged service tensile strength. Fatigue life is a measure of the use-ful life, or the number of cycles of loading, of a specified magnitude that canbe withstood by a material without failure.

Flash point. The minimum temperature at which a material or its vaporwill ignite or explode.

Flow, or creep. The gradual continuous distortion of a material under con-tinued load, usually at high temperatures.

Fusibility. The ease with which a material is melted.

Hardness. A property applied to solids and very viscous liquids to indicatesolidity and firmness in substance or outline. A hard substance does not read-ily receive an indentation.

Hygroscopic. Readily absorbing and retaining moisture.

Impact strength. The force in foot pounds (joules) required to break amaterial when struck with a sudden blow.

Iodine value. The number of grams of iodine absorbed by 100 g of fat orfatty oil. It gives a measure of the chemical unsaturation of an oil or fat. Highiodine value, 117 to 206, in vegetable oils indicates suitability of the oil foruse in paints. Low iodine value, not subject to oxidation, indicates nondryingquality suitable for soaps.

Malleability. The property of being permanently deformed by compressionwithout rupture, that is, the ability to be rolled or hammered into thin sheets.

Modulus of elasticity. The ratio of the unit stress to unit strain in tension orcompression within the elastic limit without fracture.

PHYSICAL AND MECHANICAL PROPERTIES 1095




Modulus of rigidity. The ratio of the unit stress to unit strain in shear ortorsion within the elastic limit without fracture.

Plasticity. The ability of a material to be permanently deformed at low load.

Porosity. The ratio of the volume of the interstices of a material to the vol-ume of its mass.

Reduction of area. The percentage difference between the area of a barbefore being subjected to stress and the area of the bar after rupture.

Resilience. The energy of elasticity—the energy stored in a material understrain within its elastic limit which will cause it to resume its original shapewhen the stress is removed. The modulus of resilience is the capacity of a unitvolume to store energy up to the elastic limit.

Saponification value. The number of milligrams of potassium hydroxiderequired to saponify 1 g of fatty oil or grease.

Shrinkage. The diminution in dimensions and mass of a material.

Softening point. The Vicat softening point for thermoplastic materials isthe temperature at which a flat-ended needle of 1-mm2 area will penetrate aspecimen to a depth of 1 mm under a load of 1,000 g when the temperature ofthe specimen is raised at a constant rate of 50°C/h.

Solubility. Capacity for being dissolved in a liquid so that it will not sepa-rate out on standing, except the excess over the percentage which the liquid(solvent) will dissolve. A suspension is a physical dispersion of particles suf-ficiently large that physical forces control their dissolution in the liquid. Acolloidal solution is a dispersion of particles so finely divided that surfacephenomena and kinetic energy control their behavior in the liquid. A colloidalsolution is close to a molecular combination.

Specific gravity. The ratio of the weight of a given volume of a material tothe weight of an equal volume of pure water at 4°C.

Specific heat. The number of calories required to raise 1 g of a material 1°Cin temperature.

Stiffness. The ability of a material to resist deflection, as determined by itsmodulus.

Strain. The distortion in a material by the action of an applied load.

Strength. The ability of a material to resist applied loads.

Stress. Force, or load, per unit area.

Tensile strength. The maximum tensile load per square unit of originalcross section that a material is able to withstand.

Thermal conductivity. The number of calories transmitted per secondbetween opposite faces of a cube, 1 cm by 1 cm by 1 cm, when the tempera-ture difference between the opposite faces of the cube is 1°C.

Thermal expansion. The coefficient of linear thermal expansion is theincrease in unit length with each change of 1° in temperature.






Thermoplastic. Capable of being molded and remolded without rupture byheat and pressure. When a material sets under heat and pressure into a hardsolid not capable of being remolded, it is called thermosetting.

Toughness. The ability of a material to resist impact, or absorb energy,without fracturing.

Ultimate strength. The stress, calculated on the maximum applied load andthe original area of cross section, which causes fracture of the material.

Yield point. The minimum tensile stress required to produce continuousdeformation in a solid material.





Order of Ductility of Metals

1. Gold 6. Aluminum2. Platinum 7. Nickel3. Silver 8. Zinc4. Iron 9. Tin5. Copper 10. Lead

Modulus of Elasticity in Tension of Materials

lb/in2 MPa

Lead (cast) 700,000 4,827Lead (hard-drawn) 1,000,000 6,895Phenolic (fabric laminated) 1,000,000 6,895Pine (static bending) 1,200,000 8,274Ash (static bending) 1,300,000 8,964Phenolic (paper base) 2,100,000 14,480Tin (cast) 4,000,000 27,580Tin (rolled) 5,700,000 39,300Glass 8,000,000 55,160Brass 9,000,000 62,100Aluminum (cast) 10,000,000 68,950Copper (cast) 11,000,000 75,850Zinc (cast) 11,000,000 75,850Zinc (rolled) 12,000,000 82,740Cast iron (soft gray iron) 12,000,000 82,740Brass (cast) 13,000,000 89,640Bronze (average) 13,000,000 89,640Phosphor bronze 13,000,000 89,640Manganese bronze (cast) 14,000,000 96,530Slate 14,000,000 96,530Copper (soft, wrought) 15,000,000 103,400Cast iron (average, with steel scrap) 16,000,000 110,300Clock brass 16,600,000 114,500Copper (hard-drawn) 18,000,000 124,100Cast iron (hard, white iron) 20,000,000 137,900Malleable iron 23,000,000 158,600Wrought iron 27,000,000 186,200Carbon steel 30,000,000 206,850Alloy steel (nickel-chromium) 30,000,000 206,850Nickel 30,000,000 206,850Tungsten 60,000,000 413,700





Melting and Welding Temperatures

°F °C

Direct electric arc 7232 4000°Oxygen-acetylene torch 6332 3500°Electric furnace 5432 3000°Aluminum-iron oxide powder 5072 2800°Combustion furnace 3092 1700°Oxygen-hydrogen torch 2642 1450°Plasma arc welding 59,432 33,000°Electron-beam welding 18,032 10,000°Laser-beam welding 18,032 10,000°

Mohs Hardness of Minerals

Original Mohs scale Modified Mohs scale

Hardness Hardnessnumber Mineral number Material Bierbaum number

1 Talc 1 Talc 12 Gypsum 2 Gypsum3 Calcite 3 Calcite 154 Fluorite 4 Fluorite5 Apatite 5 Apatite6 Orthoclase 6 Orthoclase

7 Vitreous silica7 Quartz 8 Quartz or stellite8 Topaz 9 Topaz

10 Garnet11 Fused zirconia

9 Corundum 12 Fused alumina13 Silicon carbide14 Boron carbide

10 Diamond 15 Diamond 10,000 (1-m scratch)

Hardness Grades of Woods

1. Exceedingly hard Lignum-vitae, ebony2. Extremely hard Boxwood, lilac, jarrah, karri3. Very hard Whitethorn, blackthorn, persimmon4. Hard Hornbeam, elder, yew5. Rather hard Ash, holly, plum, elm6. Firm Teak, chestnut, beech, walnut, apple, oak7. Soft Willow, deal, alder, Australian red cedar, birch, hazel8. Very soft White pine, poplar, redwood





Knoop Hardness of Materials

Diamond 6,000–7,000 Zirconia 1,150Boron carbide 2,750 Chromium 935Aluminum boride 2,500 Quartz 710–820Titanium carbide 2,470 Feldspar (orthoclase) 560Beryllium carbide 2,400 Nickel 550Silicon carbide 2,130–2,480 Apatite 430Alumina 2,100 Steel, hardened 400–800Zirconium carbide 2,100 Glass 300–600Tantalum carbide 2,000 Magnesia 370Tungsten carbide 1,880 Copper 160Titanium nitride 1,800 Fluorite 160Zirconium boride 1,550 Calcite 135Garnet 1,360 Zinc 120Topaz 1,250–1,340 Silver 60Spinel 1,200–1,400 Cadmium 35Tungsten carbide-cobalt 1,000–1,800 Gypsum 30Beryllia 1,250

Comparative Hardness of Hard Abrasives

(Scale: Diamond 10, corundum 9)

South American brown bort 10.00South American Ballas 9.99Congo yellow (cubic crystals) 9.96Congo clear white (cubic crystals) 9.95Congo gray opaque (cubic crystals) 9.89South American carbonadoes 9.82Boron carbide 9.32Black silicon carbide 9.15Green silicon carbide 9.13Tungsten carbide (13% cobalt) 9.09Fused alumina (3.14% TiO2) 9.06Fused alumina 9.03African crystal corundum 9.00Rock-crystal quartz 8.94

Thermal Conductivity of Materials*

Conductivity measured in British thermal units transmitted per hour per square foot ofmaterial 1 in thick, per degree Fahrenheit difference in temperature of the two faces.

Silver 2,920.0 Diatomite block 0.58Copper 2,588.0 Magnesia, 85% 0.51Steel, 1.0 carbon 328.0 Wood pulp board 0.39Building stone 12.50 Bagasse board 0.35Slate, shingles 10.37 Cork, ground 0.31Concrete, 1:2:4 6.10 Flax fiber 0.31Glass, plate 5.53 Diatomite powder 0.308Brickwork, mortar bond 4.00 Mineral wool 0.296Gypsum plaster 2.32 Asbestos sheet 0.29Brick, dry 1.21 Vermiculite 0.263Airspace, 3.5 in 1.10 Wool 0.261Pine wood 0.958 Hair felt 0.26Clay tile 0.60 Cotton, compressed 0.206

*From Paul M. Tyler, U.S. Bureau of Mines.





Linear Expansion of Metals

Unit length increase per degree Celsius rise in temperature.

Cast iron 0.000010Steel 0.000011Cobalt 0.000012Bismuth 0.000013Gold 0.000014Nickel 0.000014Copper 0.000017Brass 0.000019Silver 0.000019Tobin bronze 0.000021Aluminum 0.000024Zinc 0.000026Tin 0.000027Lead 0.000028Cadmium 0.000029Magnesium 0.000029

Melting Point of Materials Commonly Used for Heat-Treating Baths

Melting point

Material °F °C

35% lead 358 18165% tin50% sodium nitrate 424 21850% potassium nitrateTin 450 232Sodium nitrate 586 308Lead 620 327Potassium nitrate 642 33945% sodium chloride 1154 62355% sodium sulfateSodium chloride (common salt) 1474 801Sodium sulfate 1618 881Barium chloride 1760 960





Relative values of electrical insulating materials

The usual comparisons of insulating values of materials are made onthe basis of their dielectric strength. The dielectric strength of amaterial is the voltage that a material of a given thickness will resist.It is usually given in volts per mil (1 mil equals 0.001 in) or volts permeter. In any higher voltage the dielectric strength will permit aspark to pass through the material. The quoted dielectric strengths,however, are generally the minimum for the materials.

Dielectric strength Dielectric strength

Material 106 V/m V/mil Material 106 V/m V/mil

Mica, muscovite 39.4 1,000 Buna rubbers 20.3 515Glass 35.5 900 Vinylidene chloride 19.7 500Mica, phlogopite 31.5 800 Fish paper 19.7 500Electrical porcelain 31.5 800 Methyl methacrylate 18.9 480Steatite 29.6 750 Cellulose acetate 15.8 400Hard rubber 27.6 700 Casein plastic 15.8 400Silicone rubber 23.6 600 Shellac 15.8 400Polystyrene 23.6 600 Varnished cambric 15.8 400Pyroxylin 23.6 600

General Forging Temperature Range of Metals

Temperature

Metal °F °C

Aluminum alloys 600 to 1020 315 to 550Cobalt-base superalloys 2150 to 2280 1175 to 1250Columbium alloys 1700 to 3000 925 to 1650Copper alloys 1100 to 1650 595 to 900Iron-base superalloys 1900 to 2160 1040 to 1180Magnesium alloys 480 to 975 250 to 525Molybdenum alloys 1900 to 2700 1040 to 1480Nickel-base superalloys 1900 to 2200 1040 to 1205Steels

Carbon steels, 1010 to 1090 2150 to 2400 1150 to 1315Alloy steels, 41XX to 93XX 2200 to 2400 1205 to 1315Stainless steels 1500 to 2300 815 to 1260

Tantalum alloys 1800 to 2460 980 to 1340Titanium alloys 1200 to 2050 650 to 1120Tungsten alloys 2000 to 3500 1095 to 1925





Electrical Conductivity of Elements

Silver 100.00 Iron 14.57Copper 97.61 Platinum 14.43Gold 76.61 Tin 14.39Aluminum 63.00 Tungsten 14.00Tantalum 54.63 Osmium 13.98Magnesium 39.44 Titanium 13.73Sodium 31.98 Iridium 13.52Beryllium 31.13 Ruthenium 13.22Barium 30.61 Nickel 12.89Zinc 29.57 Rhodium 12.60Indium 26.98 Palladium 12.00Cadmium 24.38 Steel 12.00Calcium 21.77 Thallium 9.13Rubidium 20.46 Lead 8.42Cesium 20.00 Columbium 5.13Lithium 18.68 Vanadium 4.95Molybdenum 17.60 Arsenic 4.90Cobalt 16.93 Antimony 3.59Uranium 16.47 Mercury 1.75Chromium 16.00 Bismuth 1.40Manganese 15.75 Tellurium 0.001

The Electrochemical Series of Elements

In this table, the elements are electropositive to the ones which follow them, and willdisplace them from solutions of their salts.

1. Cesium 23. Nickel 45. Silicon2. Rubidium 24. Cobalt 46. Titanium3. Potassium 25. Thallium 47. Columbium4. Sodium 26. Cadmium 48. Tantalum5. Lithium 27. Lead 49. Tellurium6. Barium 28. Germanium 50. Antimony7. Strontium 29. Indium 51. Carbon8. Calcium 30. Gallium 52. Boron9. Magnesium 31. Bismuth 53. Tungsten

10. Beryllium 32. Uranium 54. Molybdenum11. Ytterbium 33. Copper 55. Vanadium12. Erbium 34. Silver 56. Chromium13. Scandium 35. Mercury 57. Arsenic14. Aluminum 36. Palladium 58. Phosphorous15. Zirconium 37. Ruthenium 59. Selenium16. Thorium 38. Rhodium 60. Idodine17. Cerium 39. Platinum 61. Bromine18. Didymium 40. Iridium 62. Chlorine19. Lanthanum 41. Osmium 63. Fluorine20. Manganese 42. Gold 64. Nitrogen21. Zinc 43. Hydrogen 65. Sulfur22. Iron 44. Tin 66. Oxygen





Flammability Characteristics of Common Gases and Liquids1

Flammability MaximumBoiling Flash Autoignition limit in air, oxygen point2 point3 temperature4 volume %5 content,

Material °F °C °F °C °F °C Lean limit Rich limit volume %6

Acetaldehyde 70 21.2 36 2.2 365 185 4.1 55 12Acetone 133 56.2 0 17.8 1000 538 2.6 12.8 11.6Acetylene 119 84 — — 571 300 2.5 81 —Allyl chloride 113 45 25 31.7 737 392 3.3 11.1 12.6Ammonia 28 33.3 — — 1204 652 16 25 15Benzene 176 80 12 11.1 1044 563 1.47 7.1 11.21, 3-Butadiene 24 4.4 — — 804 429 2 11.5 10.4Butane 32 0 — — 761 405 1.9 8.5 12.1Butyl acetate 259 126 79 26.1 789 421 1.7 7.6 11.51-Butene 20 6.7 — — 723 384 1.6 9.3 11.42-Butene 34 1.1 — — 615 324 1.8 9.7 11.7N-butyl formate 225 107 64 17.8 612 322 1.7 8 12.4Carbon disulfide 115 46.1 22 30 212 100 1.3 44 5.4Carbon monoxide 310 190 — — 1128 609 12.5 74 5.6Cyclopropane 27.4 33 — — 928 498 2.4 10.4 11.71, 1-Dichloroethylene 99 37.3 5 20.6 856 458 5.6 11.4 102, 2-Dimethylbutane 121 49.5 54 47.8 797 425 1.2 7 12.1Ethane 127 88.4 — — 959 515 3 12.5 11Ethanol 173 78.4 55 48.4 793 423 4.3 19 10.6Ethyl acetate 171 77.3 28 2.2 798 426 2.2 11.5 11.2Ethyl bromide 101 38.4 — — 952 512 6.7 11.3 14Ethyl chloride 54 12.1 58 50 966 519 3.8 15.4 13Ethylene 152 102 — — 842 450 3.1 32 10Ethylene oxide 56.4 13.6 017.8 804 429 3 100 —Ethyl ether 94 34.4 49 45 356 180 1.9 48 —Ethyl glycol 273.2 134.1 100.4 38 460 238 1.8 14 10.7Ethyl formate 130 54.4 4 20 851 455 2.7 13.5 10.4Ethylglycol acetate 312.8 156.1 134.6 57 716 380 1.7 — 11Gasoline — — 49 45 996 536 1.4 7 —Gasoline (60 octane) — — 45 42.8 536 280 1.4 7.6 11.6Gasoline (92 octane) — — — — 734 390 1.5 7.6 11.6Gasoline (100 octane) — — 36 37.8 853 457 1.4 7.4 11.6Heptane 209 98.4 25 3.89 433 223 1.2 6.7 11.6Hexane 156.2 69.1 7 21.7 453 234 1.2 7.5 11.9Hydrogen 422 252 — — 1085 586 4 75 5Isobutane 11 11.7 — — 864 463 1.8 8.4 12Isopropanol 179.6 82.1 70 21.1 860 460 2 12 12Isopropyl ether 154.4 68.1 18 27.8 830 443 1.4 21 10Methane 263 164 — — 999 538 5.3 14 12.1Methanol 151 66.2 52 11.1 867 464 7.3 35 9.7Methylethylketone 176 80 26 3.3 960 516 1.8 12 11.4Methylisobutylketone 242.6 117.1 73.4 23 858 459 1.4 7.5 12Methyl acetate 135 57.3 14 10 935 502 3.1 16 10.9Methylamine 19.4 7 — — 806 430 4.9 20.7 10.7Methyl butene 87.4 31.4 20 6.7 — — — — 11.4Methyl chloride 11 23.9 — — 1170 632 10.7 17.4 15Methyl formate 89.6 32 2 18.9 853 456 5.9 20 10.1




Flammability Characteristics of Common Gases and Liquids1 (Continued)

Flammability MaximumBoiling Flash Autoignition limit in air, oxygen point2 point3 temperature4 volume %5 content,

Material °F °C °F °C °F °C Lean limit Rich limit volume %6

N-butanol 244.4 118.1 95 35 649 343 1.4 11.2 11.3Pentane 97 36.1 40 40 588 309 1.5 7.8 12.1Propane 44 42.2 — — 871 466 2.2 10 11.4Propylene 54.4 48 — — 770 410 2.4 10.3 11.5Propylene oxide 93 33.9 35 37.3 869 465 2–2.1 21.5–22 10Toluene 230 110 39.2 4 996 536 1.4 7 9.1tert-Butylamine 112 44.4 16 8.9 716 380 1.7 8.9 11Vinyl chloride 9 12.8 — — 882 473 4 22 9Xylene 284 140 85 29.5 867 464 1.1 7 8

1From Philippe B. Laut and David W. Johnstone, Air Liquide America, Chemical Engineering, June 1994.2At standard atmospheric pressure.3Minimum temperature at which vapors of a combustible liquid will be ignited by a flame under certain

experimental conditions.4Minimum temperature at which a material will spontaneously oxidize in air.5Volume percent of combustible gas in air such that below the lean limit or above the rich limit the mix-

ture is considered nonflammable.6Maximum oxygen content in a combustible gas mixture below which the mixture is nonflammable.7At 212°F (100°C).


Carcinogens—Substances and Materials Known to be Cancer-Causing in Humans*

Name or synonym Year first listed†

Aflatoxins 1980Alcoholic beverage consumption 20004-aminobiphenyl (4-aminodiphenyl) 19802-aminonaphthalene (see 2-naphthylamine) 1980Analgesic mixtures containing phenacetin 1985Arsenic compounds, inorganic 1980Asbestos 1980Azathioprine 1985Benzene 1980Benzidine 1980Bis (chloromethyl) ether 1980Busulfan (see 1,4-butanediol dimethylsulfonate 19851,3-butadiene 1989‡, 2000¶1,4-butanediol dimethylsulfonate (Myleran, Busulfan) 1985Cadmium 1980‡, 2000¶Cadmium chloride 1980†, 2000¶Cadmium oxide 1980‡, 2000¶Cadmium sulfate 1980‡, 2000¶Cadmium sulfide 1980‡, 2000¶Chlorambucil 19811-(2-chloroethyl)-3(4-methylcyclohexyl)-1 nitrosourea (MeCCNU) 1991Chloromethyl methyl ether 1980Chromium hexavalent compounds 1980Coal tar 1980





Carcinogens—Substances and Materials Known to be Cancer-Causing in Humans* (Continued)


Coke oven emissions 1980Creosote (coal) 1985Creosote (wood) 1985Cristobalite 1991‡, 2000¶Cyclophosphamide 1980Cyclosporin A (cyclosporine A; ciclosporin) 1997Diethylstilbestrol 1980Direct black 38 1983‡, 2000¶Direct blue 6 1983‡, 2000¶Dyes metabolized to benzidine 2000Erionite 1980Ethylene oxide 1981‡, 2000¶Lead chromate 1980MeCCNU [1-(2-chloroethyl)-3-(4-methylhexyl)-1-nitrosourea] 1991Melphalan 1980Methoxsalen with ultraviolet A (long-wave) therapy (PUVA), 1985not carcinogenic alone

Mineral oils 1980Mustard gas 1980Myleran (1,4-butanediol dimethylsulfonate) 19852-naphthylamine (ß-naphthylamine; 2-aminonaphthalene) 1980Piperazine estrone sulfate 1985Quartz, respirable size 1991‡, 2000¶Radon 1994Sodium equilin sulfate 1985Sodium estrone sulfate 1989Solar radiation and exposure to sunlamps and sunbeds 2000Soots 1980Sulfuric-acid-containing strong, inorganic, acid mists 2000Strontium chromate 1980Tamoxifen 2000Tars 19802,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or Dioxin) 2001‡Thiotepa [tris (1-aziridinyl) phosphine sulfide] 1981‡, 1997¶Thorium dioxide 1981Tobacco smoking 2000Tobacco, smokeless 2000Tridymite, respirable size 1991‡, 2000¶Tris (1-aziridinyl) phosphine sulfide (Thiotepa) 1981‡, 1997¶Vinyl chloride 1980Zinc chromate 1980

*From “9th Report on Carcinogens, 2000,” U.S. Department of Health and HumanServices, Public Health Service, National Toxicology Program, National Institute ofEnvironmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709.

†Year of Report on Carcinogens when first listed.‡First listed as “reasonably anticipated to be a human carcinogen.”¶First listed as “known to be a human carcinogen.”





Substances and Materials Reasonably Anticipated to be Carcinogenic in Humans*


Acetaldehyde 19912-acetylaminofluorene 1981Acrylamide 1991Acrylonitrile 1981Adriamycin (doxorubicin hydrochloride) 19852-aminoanthraquinone 1983o-aminoazotoluene 19891-amino-2-methylanthraquinone 1983Amitrole 1981o-anisidine hydrochloride 1983Aroclor (polychlorinated biphenyls) 1981Aroclor 1254 (polychlorinated biphenyl) 1981Aroclor 1260 (polychlorinated biphenyl) 1983Azacitidine (5-azacytidine) 1997BCNU [bis (chloroethyl) nitrosourea] 1985Benz(a)anthracene 1981Benzo(b)fluoranthene 1981Benzo(j)fluoranthene 1981Benzo(k)fluoranthene 1981Benzo(a)pyrene 1981Benzotrichloride 1985Beryllium-aluminum alloy 1981Beryllium chloride 1981Beryllium fluoride 1981Beryllium hydroxide 1981Beryllium oxide 1981Beryllium phosphate 1981Beryllium sulfate and its tetrahydrate 1981Beryllium zinc silicate 1981Beryllium ore 1981Bis(chloroethyl) nitrosourea (BCNU) 1985Bis(dimethylamino) benzophenone 1983Bis(2-ethylhexyl) phthalate 1983Bromodichloromethane 1991Butylated hydroxyanisole (BHA) 1991Carbon tetrachloride 1981CCNU [1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea] 1985Ceramic fibers 1994Chlordecone 1981Chlorendic acid 1989Chlorinated paraffins (C12, 60% chlorine) 19891-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) 1985Chloroform 19813-chloro-2-methylpropene 19894-chloro-o-phenylenediamine 1985Chloroprene 2000p-Chloro-o-toluidine 1997p-Chloro-o-toluidine hydrochloride 1997Chlorozotocin 1997C.I. basic red 9 monohydrochloride 1989Cisplatin 1991





Substances and Materials Reasonably Anticipated to be Carcinogenic in Humans* (Continued)


p-cresidine 1981Cupferron 1983Decarbazine 1985Danthron (1-8-dihydroxyanthraquinone) 1997DDT (dichlorodiphenyltrichloroethane) 1985Decabromobiphenyl 1983DEPH [di(2-ethylhexyl) phthalate] 1983DEN (N-nitrosodiethylamine) 19812,4-diaminoanisole sulfate 1983Diaminodiphenyl ether 19892,4-diaminotoluene 1981Dibenz(a,h)acridine 1981Dibenz(a,j)acridine 1981Dibenz(a,h)anthracene 19817H-dibenzo(c,g)carbazole 1981Dibenzo(a,e)pyrene 1981Dibenzo(a,h)pyrene 1981Dibenzo(a,i)pyrene 1981Dibenzo(a,l)pyrene 19811,2-dibromo-3-chloropropane 19811,2-dibromoethane (ethylene dibromide, EDB) 19811,4-dichlorobenzene (p-dichlorobenzene) 19893,3′-dichlorobenzidine 19813,3′-dichlorobenzidine dihydrochloride 1991Dichlorodiphenyltrichloroethane (DTT) 19851,2-dichloroethane (ethylene dichloride) 1981Dichloromethane (methylene chloride) 19891,3-dichloropropene (technical grade) 1989Diepoxybutane 1983Diesel exhaust particulates 2000N,N-diethyldithiocarbamic acid 2-chloroallyl ester 1983Di(2-ethylhexyl)phthalate [DEHP, bis(2-ethylhexyl phthalate)] 1983Diethylnitrosamine 1981Diethyl sulfate 1985Diglycidyl resorcinol ether 19891,8-dihydroxyanthraquinone (Danthron) 19973,3′-dimethoxybenzidine 19834-dimethylaminoazobenzene 19813,3′-dimethylbenzidine 1983Dimethylcarbamoyl chloride 19811,1-dimethylhydrazine(UDMH) 1985Dimethylnitrosamine 1981Dimethyl sulfate 1981Dimethylvinyl chloride 19911,6-dinitropyrene 19971,8-dinitropyrene 19971,4-dioxane 1981Disperse blue 1 1997DMN (N-Nitrosodimethylamine) 1981Doxorubicin hydrochloride 1985ENU [N-nitroso-N-ethylurea (N-ethyl-N-nitrosourea)] 1981






Epichlorohydrin 1985Estradiol-17ß (estrogen, not conjugated) 1985Estrone (estrogen, not conjugated) 1985Ethinylestradiol (estrogen, not conjugated) 1985Ethyl carbamate 1983Ethylene dibromide 1981Ethylene dichloride 1981Ethylene thiourea 1983Ethyl methanesulfonate 1991N-ethyl-N-nitrosourea 1981FireMaster BP-6 (polybrominated biphenyls) 1983FireMaster FF-1 (hexabromobiphenyl) 1983Formaldehyde gas 1981Furan 1997Glasswool 1994Glycidol 1994Hexabromobiphenyl (FireMaster FF-1) 1983Hexachlorobenzene 1983-hexachlorocyclohexane 1981ß-hexachlorocyclohexane 1981-hexachlorocyclohexane 1981Hexachlorocyclohexane 1981Hexachloroethane 1994Hexamethylphosphoramide 1985Hydrazine 1983Hydrazine sulfate 1983Hydrazobenzene 1981Indeno(1,2,3-cd)pyrene 1981Iron Dextran Complex 1981Isoprene 2000Kenechlor 500 1983Kepone (chlordecone) 1981Lead acetate 1981Lead phosphate 1981Lindane (hexachlorocyclohexane) 1981MBOCA [(4,4′-methylenebis (2-chloraniline)] 1983Mestranol (estrogen, not conjugated) 19852-methylaziridine (propylenimine) 19855-methylchrysene 19814,4′-methylenebis(2-chloraniline) (MBOCA) 19834,4′-methylenebis(N,N-dimethylbenzenamine) 1983Methylene chloride 19894,4′-methylenedianiline 19854,4′-methylenedianiline dihydrochloride 1985Methyl methanesulfonate 1991N-methyl-N-nitro-N-nitrosoguanidine 1991N-methyl-N-nitrosourea 1981Metronidazole 1985Michler’s ketone [4,4′-(dimethylamino)benzophenone] 1983Mirex 1981Nickel 1980








Nickel acetate 1980Nickel carbonate 1980Nickel carbonyl 1980Nickel hydroxide 1980Nickelocene 1980Nickel oxide 1980Nickel subsulfide 1980Nitrilotriacetic acid 1980O-nitroanisole 19976-nitrochrysene 1997Nitrofen 1983Nitrogen mustard hydrochloride 19852-nitropropane 19851-nitropyrene 19974-nitropyrene 1997N-nitroso-n-butyl-N(3-carboxpropyl)amine 1981N-nitroso-n-butyl-N(4-hydroxybutyl)amine 1981N-nitrosodi-n-butylamine 1981N-nitrosodiethanolamine 1981N-nitrosodiethylamine (diethylnitrosamine, DEN) 1981N-nitrosodimethylamine (dimethylnitrosamine, DMN) 1981N-nitrosodi-n-propylamine 1981N-nitroso-N-ethylurea (N-ethyl-N-nitrosourea, ENU) 19814-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) 1991N-nitroso-N-methylurea (N-methyl-N-nitrosourea) 1981N-nitrosomethylvinylamine 1981N-nitrosomorpholine 1981N-nitrosonornicotine 1981N-nitrosopiperidine 1981N-nitrosopyrrolidine 1981N-nitrososarcosine 1981NNK [4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone] 1991Norethisterone 1985Ochratoxin A 1991Octabromobiphenyl 19834-4′-oxydianiline 1989Oxymetholone 1980PAHs (polycyclic aromatic hydrocarbons) 1989PBBs (polybrominated biphenyls) 1983PCBs (polychlorinated biphenyls) 1981Perchloroethylene 1989Phenacetin 1980Phenazopyridine hydrochloride 1981Phenolphthalein 2000Phenoxybenzamine hydrochloride 1989Phenytoin 1980Polybrominated biphenyls (PBBs) 1983Polychlorinated biphenyls (PCBs) 1981Polycyclic aromatic hydrocarbons (PAHs) 1989Procarbazine hydrochloride 1981Progesterone 1985






1,3-propane sultone 1985ß-propiolactone 1981Propylene oxide 1991Propylenimine 1985Propylthiouracil 1985Reserpine 1981Safrole 1981Selenium sulfide 1983Streptozotocin 1981Sulfallate 19832,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)‡ 1981Tetrachloroethylene (perchloroethylene) 1989Tetrafluoroethylene 2000Tetranitromethane 1994Thioacetamide 1983Thiourea 1983Toluene diisocyanate 1985o-toluidine 1983o-toluidine hydrochloride 1981Toxaphene 1981Trichloroethylene 20002,4,6-trichlorophenol 19831,2,3-trichloropropane 1997Tris(2,3-dibromopropyl) phosphate 1981UDMH (1,1-dimethylhydrazine) 1985Urethane (Urethan, ethyl carbamate) 19834-vinyl-1-cyclohexene diepoxide 1994 1994

*From “9th Report on Carcinogens, 2000” U.S. Department of Health and HumanServices, Public Health Service, National Toxicology Program, National Institute ofEnvironmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709.

†Year of Report on Carcinogens when first listed.‡This substance has been proposed for the “known to be a human carcinogen” category.Proposed listing is currently in litigation.





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