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Transcript of 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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Pioneering Advanced Ceramics
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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Pioneering Advanced Ceramics
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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Pioneering Advanced Ceramics
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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Pioneering Advanced Ceramics
Composite Brake Rotor Lay-up
- 45o
0o
+ 45o
90o
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Pioneering Advanced Ceramics
6k T-300 Reinforced SMP-10 with SiC Filler
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Pioneering Advanced Ceramics
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!