Influence of the preparation temperature on the phase, microstructure and anti-oxidation property of a SiC coating for C/C composites

A SiC coating for carbon/carbon(C/C) composites was produced by a pack cementation technique in an argon atmosphere. The phase, microstructure and anti-oxidation property of the SiC coatings prepared from 1773 to 2273 K were investigated. It is found that the porous β-SiC coatings occur at 1773-1973 K while dense Si/β-SiC coatings generate at 2073 K and micro-cracked β-SiC/α-SiC coatings appear at 2173-2273 K. The thickness of the SiC coating increased with increasing temperature and oxidation tests at 1773 K in air showed that, based on observed weight changes, a preparation temperature of 2073-2273 K gave much improved oxidation resistance over that of coatings formed between 1773 and 1973 K.