unit.5.nonmetallic matls. cbn.nd diamond. notes

8/9/2019 Unit.5.Nonmetallic Matls. Cbn.nd Diamond. Notes

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NON METALLIC

MATERIALS

(i) Cubic Boron

Nitride(CBN(ii) DIAMONDS


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Cubic Boron Nitride(CBN

Cubic Boron Nitride(CBN)

Superabrasives

Cubic Boron Nitride(cBN) is second in

hardness on! todia"ond


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Cubic Boron Nitride

Cubic boron nitride (CBN) is as!nthetic che"ica co"pound "adeup o$ boron and nitro%en ato"s in a

one&to&one ratio' nie other t!pes o$ boron nitride* it

e+ists as acubic cr!sta attice* ,ithits ato"s arran%ed in a s!""etrica*cube&shaped structure ie thecr!staine structure o$ dia"ond'


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Cubic Boron Nitride

Its "ateria properties incudee+tre"e hardness* stabiit! underheat* and superior che"ica

resistance' Cubic boron nitride is the second&

hardest no,n "ateria a$terdia"ond* "ain% it use$u in a ,idevariet! o$ industria appications*,here it is o$ten used as an abrasiveor cuttin% too'


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Cubic Boron Nitride

A boron nitride co"pounds areproduced s!nthetica!* since the!are not $ound in nature'

The process starts ,ith boric acid* a

co"pound o$ boron* o+!%en* andh!dro%en* or ,ith borontrio+ide*,hich is "ade up o$ boron and

o+!%en' Either o$ these co"poundscan be reacted ,ith urea ora""onia* ,hich contain nitro%en* toproduce a po,der o$ boron nitride'


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Cubic Boron Nitride

The po,der is cr!stai-ed throu%hintense heat to $or"he+a%ona boron nitride* ,hich

has a he+a%ona cr!sta structureanao%ous to that o$ %raphite*aprecursor o$ s!nthetic dia"ond'

.e+a%ona boron nitride is thenheat&treated under hi%h pressureto $or" cubic boron nitride
http://www.wisegeekhealth.com/what-is-boric-acid.htmhttp://www.wisegeekhealth.com/what-is-boric-acid.htm


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Cubic Boron Nitride

CBN has severa advanta%es as an industria"ateria'

It is a"ost as hard as dia"ond* "ain% ituse$u $or cuttin% and abrasion o$ "etas andother substances' The heat resistance o$ CBN is

aso /uite hi%h' Dia"ond be%ins to deco"pose to

carbon dio+idein air at around 0112C*,hereas cubic boron nitride is stabe in air up

to about 3*4112C' In industria %rindin% appications and other

processes ,here intense heatis %enerated*CBN is pre$erred over dia"ond'


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Cubic Boron Nitride

Another advanta%e o$ CBN as anaternative to dia"ond is its che"icastabiit! in the presence o$ nice* iron*and reated substances'

Dia"ond is soube in these "etas*"eanin% that it reacts ,ith the"che"ica! and dissoves'

This "aes it useess as a too $or cuttin%

iron or stee' CBN* on the other hand* does not react

and can there$ore be used to cut these"aterias
http://www.wisegeek.com/what-is-carbon-dioxide.htmhttp://www.wisegeek.com/what-is-carbon-dioxide.htm


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Cubic Boron Nitride

The variet! o$ CBN used in industriacuttin% toosis no,n aspo!cr!staine cubic boronnitride (5CBN)'

5CBN is "anu$actured b!sinterin% cubic boron nitride partices,ith cera"ics'

In sinterin%* the boron nitride is paced ina $urnace under hi%h heat and pressure

that binds it ,ith the cera"ic* $usin% intothe e+tre"e! hard substance used $or%rindin% and cuttin%'


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DIAMONDS
http://www.wisegeek.com/what-are-the-different-types-of-cutting-tools.htm


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DIAMONDS

Dia"ond is the aotrope o$ carbonin,hich the carbonato"s are arran%edin the speci6c t!pe o$ cubic attice

caed dia"ond cubic' Dia"ondis an optica! isotropic

cr!stathat is transparent to opa/ue'

O,in% to its stron% covaent bondin%*

dia"ond is the hardestnatura!occurrin% "ateria no,n'


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DIAMONDS

Due to i"portant structura,eanesses* dia"ond7stou%hnessis on! $air to %ood'

The precise tensie stren%tho$dia"ond is unno,n* ho,everstren%th up to 81 95ahas been

observed* and it coud be ashi%h as :1;


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DIAMONDS

The anisotrop!o$ dia"ond hardness iscare$u! considered durin%dia"ond cuttin%' Dia"ond has ahi%h re$ractive

inde+ (


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DIAMONDS

Trace i"puritiessubstitutiona! repacin%

carbon ato"s in adia"ond7s cr!sta attice* andin so"e cases structura

de$ects* are responsibe $orthe ,ide ran%e o$ coors seenin dia"ond'
http://en.wikipedia.org/wiki/Diamond_cuttinghttp://en.wikipedia.org/wiki/Anisotropy


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DIAMONDS

Most dia"onds are eectricainsuators but e+tre"e!

e@cient ther"a conductors'nie "an! other "ineras*the speci6c %ravit! o$

dia"ond cr!stas ('=


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DIAMONDS

A tra! o$ dia"ond heatspreaders'

The! are used ineectronic devices andother paces ,here a oto$ heat is %enerated in as"a area'


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DIAMONDS

Dia"onds can survive conditionsthat ,oud destro! other "ateriasand so the! have "an! uses in

science and industr!' Natura dia"onds are rare andver! e+pensive so it hasn7t been

possibe to "ae $u use o$ theira"a-in% natura properties untirecent!'


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DIAMONDS

No, ,e have the abiit!to %ro, s!nthetic

dia"ond cr!stas and,a$ers* openin% up

,hoe ne, ,ords o$technoo%!'


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DIAMONDS

Dia"onds have a ran%e o$ uni/ue properties Dia"ond is the hardest no,n natura

"ateria on Earth'

Dia"ond conducts heat = ti"es $aster than

copper*,hich is ,h! it $ees cod to thetouch'

5ure dia"ond is the "ost transparent"ateria no,n'

It reects visibe i%ht* utra&vioet i%ht* andin$rared i%ht* and a the $re/uenciesinbet,een'


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DIAMONDS

Dia"ond can be an insuator or aconductor* so it can either ao,eectricit! to pass throu%h or

boc it'

Dia"ond can survive intact inenviron"ents that ,i destro!

other "aterias' It can survivesevere ph!sica* che"ica andradioactive $orces'


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DIAMONDS

I$ !ou pace dia"ondsinside the hu"anbod! the! ,i nottri%%er an i""une

response


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DIAMONDS

No, ,e can "aearti6cia dia"onds* ,e

can "ae better use o$these properties inscience and en%ineerin%'.ere are so"e e+a"pes'


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DIAMONDS

Sur%er! Dia"ond bades on scapes have

an utra&6ne ed%e that can cut ver!precise!* ,hich is i"portant $orsur%er!'

Dia"ond aso re"ains sharp $or"uch on%er than stee' As it cuts*

it can trans"it aser i%ht* ,hichao,s it to cauterise the ,ound tocontro beedin%'


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DIAMONDS

Teeco""unications Dia"ond cubes can ao, severa

si%nas at once to pass aon% a

cabe* a at dierent ,aveen%thso$ i%ht' This "aes the" use$uin teeco""unications'

The! can aso ,ithstand hi%h&ener%! conditions and chan%es inte"perature'


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DIAMONDS

.eat spreaders

.eat passes throu%h dia"onds $ar"ore /uic! than it passes

throu%h copper'

This "aes it use$u as a heatspread in paces ,here ots o$ heat

is %enerated in a s"a space' Microeectronic devices are one

e+a"pe'


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DIAMONDS

indo,s

Dia"ond ,indo,s provide protection$ro" e+tre"e conditions in so"e

scienti6c e+peri"ents that usesubstances ie acidic i/uids or"oten pastics'

Dia"onds ,indo,s are aso ver!

transparent and so the! ao, in$ra&red "easurin% devices to "onitor thesubstances sa$e! $ro" behind the,indo,'

DIAMONDS


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DIAMONDS

A diamond window


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DIAMONDS

.eath care

Dia"ond is "ade o$ carbon and

so it is the idea "ateria to usein our carbon&based bodies'

It ,i not ,ear a,a! or tri%%er

an i""une response'


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DIAMONDS

Scientists are deveopin%dia"ond i"pants that coudhep "onitor heath or tae

over the roe o$ $aiin% tissues' The! are aso drea"in% o$ tin!dia"ond "achines that one

da! "i%ht speed round thebod! "ain% repairs'

unit.5.nonmetallic matls. cbn.nd diamond. notes

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