Silicon Carbide: Manufacturing Processes and Material Properties

1. Silicon Carbide:Manufacturing Processes and Material Properties B. C. Bigelow, UM Physics 3/24/05 Bruce C. Bigelow -- UM Physics

2. 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 Bruce C. Bigelow -- UM Physics

3. Silicon Carbide for SNAP This talk: • Brief history • Manufacturing processes • Commercial sources • Material properties • Spacecraft heritage • Current applications • Conclusions Bruce C. Bigelow -- UM Physics

4. 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 Bruce C. Bigelow -- UM Physics

5. 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 Bruce C. Bigelow -- UM Physics

6. 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 Bruce C. Bigelow -- UM Physics

7. Selected Sources for SiC • BOOSTEC (Tarbes, France) • Cercom (Vista, CA) • Ceradyn (Costa Mesa, CA) • Coorstek (Golden, CO) • GE Power System Composites (Newark, DE) • IBCOL (Munich, Germany) • Kyocera Advanced Materials (Vancouver, WA) • Poco Graphite (Decatur, TX) • SSG Precision Optronics (Wilmington, MA) – no mat props. • Trex Enterprises (Lihue, HI) • Rohm & Haas (Woburn, MA) • Saint Gobain / Carborundum (Niagara Falls, NY) Bruce C. Bigelow -- UM Physics

8. SiC fabrication - IBCOL Bruce C. Bigelow -- UM Physics

9. Picture of the Week SiC fabrication - Boostec Bruce C. Bigelow -- UM Physics

10. R. Temp SiC Material Properties Bruce C. Bigelow -- UM Physics

11. SiC Mat. Prop. Comparisons Bruce C. Bigelow -- UM Physics

12. SiC Space Heritage Heritage missions: • NASA EO-1 ALI – SiC mirrors • ESA ROCSAT2 – SiC optical bench • ESA ROSETTA – SiC optical bench Bruce C. Bigelow -- UM Physics

13. SiC Space Heritage – EO1 Bruce C. Bigelow -- UM Physics

14. SiC Space Heritage – Rosetta Rosetta – SiC optics and optical bench Bruce C. Bigelow -- UM Physics

15. SiC Space Heritage - ESA IBCOL EADS/ESA verification structure Bruce C. Bigelow -- UM Physics

16. SiC Space Applications - Hershel 3.5m SiC primary mirror Bruce C. Bigelow -- UM Physics

17. SiC Space Applications - Hershel Hershel SiC secondary mirror support structure Bruce C. Bigelow -- UM Physics

18. ESA - GAIA GAIA optical layout – 2 fields simultaneously Bruce C. Bigelow -- UM Physics

19. ESA - GAIA GAIA focal plane mosaic – 10 x 18 = 180 CCDs 4500 x 1966 px/CCD, 1.5 Gpx Bruce C. Bigelow -- UM Physics

20. Picture of the Week SiC Space Applications - GAIA GAIA SiC primary mirror demonstrator - 1.4m x 0.5m Bruce C. Bigelow -- UM Physics

21. Picture of the Week SiC Space Applications - GAIA GAIA SiC stability verification optical bench Bruce C. Bigelow -- UM Physics

22. Picture of the Week SiC Space Applications - GAIA GAIA focal plane demonstrator model (Boostec): 770mm by 580mm by 36mm, with a mass of about 8kg. Bruce C. Bigelow -- UM Physics

23. Picture of the Week SiC Space Applications - GAIA GAIA focal plane - sintered SiC – detector mounting detail Bruce C. Bigelow -- UM Physics

24. 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 Bruce C. Bigelow -- UM Physics