Silicon Carbide: Manufacturing Processes and Material Properties

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Silicon CarbideManufacturing Processes and
Material Properties

• B. C. Bigelow, UM Physics
• 3/24/05

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Silicon Carbide for SNAP

• Motivations
• Silicon Carbide has extreme material properties
• Very high thermal conductivity
• Very low thermal expansion close match to Si
• Very high specific stiffness (E/r)
• Fabrication processes have matured
• Process-tunable material properties
• Complex geometries, assemblies
• Substantial space heritage exists
• Space science applications
• Military applications
• Structures and reflecting optics

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Silicon Carbide for SNAP

• This talk
• Brief history
• Manufacturing processes
• Commercial sources
• Material properties
• Spacecraft heritage
• Current applications
• Conclusions

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Silicon Carbide for SNAP

• History
• Accidentally discovered by Edward G. Acheson
  (assistant to Thomas Edison) in 1890, while
  trying to synthesize diamond.
• First synthesis method - Acheson Process SiC
  created intentionally by passing current through
  a mixture of clay and carbon
• Natural SiC found only in meteorites, in very
  small quantities

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Silicon Carbide for SNAP

• SiC Raw Material Production
• Acheson Process for producing powders
• Pyrolysis for producing fibers
• Reactions of silicon and carbon for producing
  whiskers

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SiC Production Processes

• Chemical Vapor Deposition (CVD) 99
  theoretical density, single phase
• Chemical Vapor Composite (CVC) CVD with
  particulate injection (Trex)
• Chemical Vapor Infiltration (CVI) graphite or
  carbon conversion / infiltration graphite
  greenbody, may be reinforced with carbon or
  other fibers (C/SiC), multi-phase final material,
  porosity varies with process, also called Ceramic
  Matrix Composite (CMC)
• Sintering trace amounts of impurities and second
  phase result from sintering additives, few
  percent porosity
• Slip Casting similar to sintering, with liquid
  mold-filling additives
• Reaction Bonding two phase mixture of SiC and
  Si, percentages and porosity vary with process
• Hot Isostatic Pressing (HIP) near-theoretical
  density, may have second phase or impurities from
  hot-pressing additives, can be very low porosity
  (inert gas compaction)
• Hot Pressing mechanical pressure compaction with
  electric current heating

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Selected Sources for SiC

1. BOOSTEC (Tarbes, France)
2. Cercom (Vista, CA)
3. Ceradyn (Costa Mesa, CA)
4. Coorstek (Golden, CO)
5. GE Power System Composites (Newark, DE)
6. IBCOL (Munich, Germany)
7. Kyocera Advanced Materials (Vancouver, WA)
8. Poco Graphite (Decatur, TX)
9. SSG Precision Optronics (Wilmington, MA) no mat
   props.
10. Trex Enterprises (Lihue, HI)
11. Rohm Haas (Woburn, MA)
12. Saint Gobain / Carborundum (Niagara Falls, NY)

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SiC fabrication - IBCOL
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SiC fabrication - Boostec
Picture of the Week
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R. Temp SiC Material Properties
Manuf. Process E, GPa Fl. Str, Mpa Kic, MPam0.5 Density, kg/m3 Poisson ratio CTE, ppm/C K, W/mK
Boostec sintered 420 450 3.5 gt3100 0.16 4.0 180
Ceradyne CVD 440 375 3.1 3200 0.17 4.5 200
HP 450 634 4.3 3200 0.17 4.8 115
sintered 430 400 4.3 3200 0.17 4.5 120
Cercom CVI 460 570 4.4 3200 0.16 4.5 130
Coorstek CVD 462 468 3.5 3210 0.21 4.6 115
RB 462 462 4-5 3100 0.20 4.4 125
sintered 410 480 4-5 3150 0.21 4.4 150
GE Cesic C/SiC 197 120 4.6 2650 2.1 125
IBCOL C/SiC 235 175 2650 2.6 135
Kyocera 430 539 5.6 3200 0.16 4.0 63
Poco CVI 218 147 2.3 2530 0.17 1.2 170
Rohm-Haas CVD 466 461 3.3 3210 0.21 2.2 300
St.Gobain sintered 410 240 4.6 3100 0.14 4.0 125
Trex CVD 466 380 3.4 3200 0.17 3.5 205-250
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SiC Mat. Prop. Comparisons
Manuf. Process E, GPa Fl. Str, Mpa Kic, Mpa-m-0.5 Density, kg/m3 Poisson ratio CTE, ppm/C K, W/mK
Ceradyne CVD 440 375 3.1 3200 0.17 4.5 200
Coorstek CVD 462 468 3.5 3210 0.21 4.6 115
Rohm-Haas CVD 466 461 3.3 3210 0.21 2.2 300
Trex CVD 466 380 3.4 3200 0.17 3.5 205-250
GE Cesic C/SiC 197 120 4.62 2650 2.1 125
IBCOL C/SiC 235 175 2650 2.6 135

AlN 330 290 2.6 3260 0.24 4.5 170
Alum 7075-T6 72 50 24 2790 0.33 23.4 160
TZM Arc cast 325 860 6-30 10160 0.32 4.9 120
Molybdenum Stress rel. 330 415 10220 0.32 5.35 138
304 St. Stl. 193 500 346 8030 0.29 16.2 16
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SiC Space Heritage

• Heritage missions
• NASA EO-1 ALI SiC mirrors
• ESA ROCSAT2 SiC optical bench
• ESA ROSETTA SiC optical bench

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SiC Space Heritage EO1
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SiC Space Heritage Rosetta
Rosetta SiC optics and optical bench
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SiC Space Heritage - ESA
IBCOL EADS/ESA verification structure
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SiC Space Applications - Hershel
3.5m SiC primary mirror
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SiC Space Applications - Hershel
Hershel SiC secondary mirror support structure
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ESA - GAIA
GAIA optical layout 2 fields simultaneously
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ESA - GAIA
GAIA focal plane mosaic 10 x 18 180 CCDs 4500
x 1966 px/CCD, 1.5 Gpx
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SiC Space Applications - GAIA
Picture of the Week
GAIA SiC primary mirror demonstrator - 1.4m x 0.5m
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SiC Space Applications - GAIA
Picture of the Week
GAIA SiC stability verification optical bench
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SiC Space Applications - GAIA
Picture of the Week
GAIA focal plane demonstrator model
(Boostec) 770mm by 580mm by 36mm, with a mass of
about 8kg.
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SiC Space Applications - GAIA
Picture of the Week
GAIA focal plane - sintered SiC detector
mounting detail
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Silicon Carbide for SNAP

• Conclusions
• There are many commercial sources for SiC
• SiC material production and fabrication methods
  are well developed
• SiC and C/SiC demonstrate extremely high
  performance material properties
• Space heritage for SiC has been established
• NASA and ESA are using of SiC in current programs
• SiC is a real option for SNAP, both for optics
  and structures