ceramic composites

8/22/2019 ceramic composites

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Pioneering Advanced Ceramics

The Development and Commercialization

of Polymer Derived Ceramic MatrixComposites

Presented at the 2006 ASM/TMS Spring Symposium


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Outline

1. Ceramic forming polymers the key to novel ceramicmaterials

2. Chemistry and structure of Si-C based polymers

3. Polymer properties control ceramic properties

4. Applications for ceramic forming polymers

5. Brake Rotors and Friction Materials

6. Test Results

7. Summary


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Why Ceramic Precursors?

Versatility wide variety of ceramics, near netshapes

Ease of use low temperature processing

Can tailor ceramic - by precursor chemistry,thermal treatment, cure/pyrolysis/heat treatmentatmosphere

Only known method to easily produce amorphousnon-oxide ceramics

Inherently produce nano-structured materials


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Cost and Scale-up Were Issues

IN THE PAST

Ceramic-forming polymers were expensive ($500 -$4000/kg)

Some were pyrophoric, produced ammonia, solids -needed oxygen or catalysts to crosslink

Low ceramic yield many infiltration and pyrolysiscycles for dense part

Laboratory curiosities, or limited to high end aerospaceapplications


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Polycarbosilanes

Silicon CarbideThermally stable,

corrosion/oxidation resistant to high temperatures HT CMCs

Polycarbosiloxanes Silicon oxycarbides lowershrinkage, widely tailorable ceramics, release coatings, frictionmodifiers, Mid Temp CMCs air stable to 1100 C

Alkoxycarbosilanes Silicon oxycarbides - thinfilms, low K dielectrics, friction modifiers, release coatings,foamed ceramics, photo-resist intermediates

Tailored Si-C Backbone Polymers

for Nano-Engineered CeramicMaterials


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Polycarbosilanes

Basic synthesis has two steps, coupling and reduction:

Resulting polycarbosilane is ideal for SiC formation

(85% yield should be possible)

CH2 SiRR'Cl Cl1. n CH2 SiRR' n

Mg, ether

CH2 SiRR' n2. CH2 SiH2 n

Reduction

R, R' = Cl, CH3, phenyl, OMe, OEt

R, R' = Cl, OM e, OEt

CH2 SiH2n

850 C, inert gas

SiC (amorphous)


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SMP-10: a practical polycarbosilane

Amber liquid, 50 150 cPs. Low toxicity. Soluble in most non-polar and many polar solvents.

Oxidizes only slowly in air at ambient temperatures.

Used at the bench top in the atmosphere with standardprotective equipment (gloves, apron, safety glasses, ventilation).

For short-term storage, inerting with nitrogen is recommended.

Shelf-life > 6 months when inerted and stored at -10 C

H CH2 SiH20.9

CH2 SiH H0.1


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SMP-10: Conversion to SiC

Allyl groups improve actual ceramic yield (75 76% for

medium MW polymer)

With both Si-H and allyl present, Pt catalysts can be usedto cure at lower temperatures (250 C)

The slight additional C content is bound to Si resulting inhigh oxidative stability (


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Si-C Forming Polymer Processing


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SMP-10 Properties and Processing Parameters:

Density (g/cc) 0.998

Appearance Clear, Amber Color

Viscosity (cps) 80-100

Solubility Hexane, Tetrahydrofuran, Acetone, Toluene

Melting Point (C/F) Less than -100/-148

Flashpoint (C/F) 89/192

Boiling Point (C/F) 160/320

Moisture Absorption (%) < 0.1% in 24 hrs at RT

Nominal Cure Temperature (C/F) 400/752


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CURING PARAMETERS

Cure Atmosphere Nitrogen, Argon, Helium

Cure Heating Rate (C/min.) 1-3 Depending on part thickness

Cure Temperature* (C/F) 400/752

Cure Hold Time (h) 1-2 hours

Fixture/Mold/Holder Material Aluminum, Brass, Steel, Graphite, Alumina

Mold Release Acrylic Spray/Tape, Kapton polyimides, Boron Nitride

PYROLYSIS PARAMETERS

Pyrolysis Heating Rate (C/min.) 1-2 Depending on part thickness and porosity

Pyrolysis Temperature (C/F) 850-1000/1562-1832

Pyrolysis Atmosphere Nitrogen, Argon, Helium

Pyrolysis Hold Time (h) 1 hour

Pyrolysis Fixture/Holder Material Steel (850C Limit), Graphite, AluminaMold Release (Needed only if NOT cured first) Same as for curing step

CRYSTALLIZATION HEAT TREATMENT

Crystallization Heating Rate (C/min.) 2 deg/min

Crystallization Temperature (C/F) 1600/3000

Crystallization Atmosphere Argon, Helium

Crystallization Hold Time (h) 6-8

Crystallization Holder Material Graphite


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SMP-10, other carbosilanes: Applications

SiC/C & SiC/SiC ceramicmatrix composites (CMCs)for friction systems: Durability, high temp. strength

Lightweight

Controlled friction behavior

CMCs & SiC powderslurries for industry: Chemical resistance, strength

Adhesives and coatings

Complex shapes easily formed


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Where to Apply Ceramic Forming Polymers??

Aerospace Still too R&D, no commercial market

Electronics high margin, huge potential have

value proposition Industrial chemical industry promising

Energy Nuclear, coal, fuel cells - future Biomaterials Long qualification cycle

TransportationHuge market, quick entry, obvious

value proposition, properties create market pull


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Ceramic Composite Brake Rotors

Quantifiable advantages over competing

materials weight, wear life, reduced noise, inversefade

Market Pull

Doesnt push performance envelope of material

Developed drop-in replacement system formetal with better performance

Can cut as much as 300 lbs from car

Already below cost of competing high end

materials MI and C/C closing in on steel


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Traditional Composite Processing

Carbon

Fabric FabricHeat Treat PrepregFabric

Cad CutPlies

350oC PressCure

Lay-upRotors

850oC

Kiln

VacuumImpregnation

Grinding

Polymer

Total

Solids

Dens

viscosity

Dim Insp

Surf Fin, DTV

Cert

Weight

Ceramic Polymer

& Fillers

Delivery

Machine


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Composite Brake Rotor Lay-up

- 45o

0o

+ 45o

90o


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6k T-300 Reinforced SMP-10 with SiC Filler


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Melt Infiltration

Chopped Fiber

Reinforcement cost Si + C SiC

Free Silicon and Carbon

Variable Crystal size Moderate Conductivity

Fiber Conversion to SiC

Low Yield due to porosity

Higher Capital Investment

Low Toughness (4MPa-m1/2)

Polymer Impregnation

Continuous Fiber

Reinforcement [SiH2-C]n SiC + H2

Stoichiometric SiC

Controllable crystal size Moderate Conductivity

Fibers Protected

Excess Strength

Low Capital Investment

High Toughness(22MPa-m1/2)

Polymer Derived Ceramic Toughness Eliminates Cracks


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2D 6k T-300 w/ Filler Mechanical Properties

Property Value Value

Tensile Strength 35 - 39ksi11-12Msi

28-38ksi

4-5ksi

.9-1ppm/oF

21.8BTU/Hr-ft-oF

5.4BTU/Hr-ft-oF

15-18ksi-in1/2

140lb/ft3

250-288MPaTensile Modulus 77-91GPa

Flex Strength 196-275MPa

Interlaminar Shear(SBS) 28-34MPa

Density gm/cm3 2.25gm/cm3

In Plane Thermal

Expansion

1.5-1.8ppm/oC

Thermal Conductivity - x,y

- z

25-40W/MK

5-8W/MK

Toughness 22MPa-m1/2


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Ducatti 999 StarBlade and Carrier5 mm thick 320 mm in diameter

6 lbs weight savings on front axle


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Motorcycle Structural Analysis

Fatigue Tested at 150%for 3000 cycles and200% for 900 cycles


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StarBladeTM

Fatigue Testing Cycles

0

100

200

300

400

500

600

700

800

900

1000

1 10 100 1000 10000 100000

Brake Cycles

Torque

Levelft-lbs


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Friction Performance:12 on a scale of 10Jason DiSalvo, Las Vegas International Speedway, Dec 9, 2004

Yamaha FactoryRacing Team

2004 YZF-R1


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Disc Pad Rider Rank

Average GlobalSensitivity

SpeedSensitivity

Tempsensitivity

Padwear

(mm)

Discwear

(mm)

CMC Sintered 12 0.65 .28 .10 .05 .890 -.003

98

9

10

9

8

CMC PRO 129 0.63 0.32 0.09 0.06 1.376 -0.009C/C C/C 0.55 0.28 0.08 0.12 3.45 0.250

Cast Iron PRO 129 0.64 0.18 0.01 0.11 0.452 0.006

Stainless

Steel

PRO 129 0.66 0.16 0.05 0.04 0.643 0.001

StainlessSteel

CP911Organic

0.60 0.14 0.06 0.02 0.672 0.001

StainlessSteel

RXSintered

0.57 0.23 0.22 0.04 0.304 -0.003

Motorcycle Friction Summary


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Composite Damping Reduces NVH

Composite rotor dampens induced noise 1800 times faster than cast iron

Damping Curves

Cast IronResonant Frequency = 956HzDamping Coeff = 4.62 sec-1

Loss Factor = .0015

Composite/Al HubResonant Freq = 1013HzDamping Coeff = 12.07sec-1

Loss Factor = .0037


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Composite Rotor Cost Reduction

13 OD Tahoe Rotor

650

305

149 125

0

200

400

600

800

1000

1000 10000 100000 1000000

Combined Volume Rotors/Year

ManufCost$/Rotor

Initial Current Probable

Current Porsche Option Cost $10,500/Boxter


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Train Rotor


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BUS Rotor - 28lbs vs 85 lbs

16,600ft-lb torque


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Summary

1. Ceramic forming polymers permit control of the composition,microstructure and properties of ceramic materials

2. A major non-aerospace commercial market for CMCs is brakerotors and friction materials

3. Polymer-derived ceramic brake rotors have been developed asdrop-in replacements for steel no redesign needed

4. Major advantages over competing high end materials MI and C/C5. Significant market pull due to lower weight, lower noise, no fade,

etc.

6. Within reach of cost targets at low volume selling product now!

ceramic composites

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