Fabrication of SiC matrix composites by liquid phase infiltration with a polymeric precursor
- Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Chemistry
- Starfire Systems, Inc., Watervliet, NY (United States)
A process for the fabrication of SiC matrix composites has been developed which employs a liquid, highly branched, polycarbosilane (AHPCS). This polymer thermosets on heating at 200--400 C (or at 100 C with catalyst) and yields an amorphous SiC with low excess C and O content in 60--80% yield on pyrolysis to 1,000 C. Preforms consisting of C-coated Nicalon SiC fiber cloth, unidirectional Textron SiC SCS-6 fiber layups, or Mo boats packed with SiC whiskers, were infiltrated with the polymer, cured in an autoclave, and pyrolized to 1,000 C. Five to eight infiltration cycles gave net shape composites with final densities at 85--94% of theoretical. The results of 4-point flexure tests on the as-prepared Nicalon composites indicate flexure strengths (aver. 378 MPa) that are comparable to or better than similarly reinforced CVI-SiC matrix composites. The whisker and SCS-6 composites showed a small weight loss (10--20%) on heating to 1,500 C in Ar and little or no weight change or obvious embrittlement in air at 1,000 C.
- OSTI ID:
- 100551
- Report Number(s):
- CONF-941144--; ISBN 1-55899-266-9
- Country of Publication:
- United States
- Language:
- English
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