Processing aluminum nitride silicon carbide composites via polymer infiltration and pyrolysis of polymethylsilane, a precursor to stoichiometric silicon carbide

AlN-SiC-particle-reinforced composites have been prepared at less than or equal to 1400 degrees C using submicrometer AlN, -325 mesh alpha-SiC particles, and polymethylsilane (PMS; -(CH3SiH)(n)-) via a polymer infiltration and pyrolysis (PIP) process. PMS is an organometallic SiC polymer precursor that can be modified with 16 wt% cross-linking aid to provide mPMS, mPMS converts to nanocrystalline beta-SiC with >80% ceramic yield (1000 degrees C in argon) with some excess (<5 wt%) graphitic carbon. mPMS has been used successfully as a nonfugitive binder for AlN-SiC compacts. Densities of 2.5 versus 2.1 g/cm(3) have been obtained after nine PIP cycles for disk-shaped compacts formulated with and without mPMS binder, respectively. alpha-SiC seeds crystallization of beta-SiC derived from mPMS at temperatures as low as 1000 degrees C. Some evidence suggests that AlN-SLC solid solutions form at particle/matrix interfaces.