α-Silicon carbide/β-silicon carbide particulate composites via polymer infiltration and pyrolysis (PIP) processing using polymethylsilane

The β-SiC precursor polymethylsilane [PMS, [(MeSiH)x,(MeSi)y]]n. Mn=2100 Da], when modified with 12 wt% crosslinking aid, gives a hyperbranched polymer (mPMS) that transforms to phase pure, nanocrystalline β-SiC with an 80–85% ceramic yield on heating to ≈1100°C/Ar. Particulate reinforced β-SiC composites (PRCs) can be formed by PIP processing green powder compacts. We describe here PIP processing of α-SiC/β-SiC PRCs using mPMS. The resulting composites have densities >2.5 g/cc (85% theory) after 10 PIP cycles. XRD and FTIR studies suggest that α-SiC seeds crystallization of mPMS derived β-SiC at temperatures ⩽1200°C.