Preparation of UHTC based coatings for C–SiC composites by slurry and CVD

Oxidation of fibre and matrix cooperatively influences the oxidation behaviour of C–SiC composites in oxygen atmosphere at higher temperatures. In order to improve the anti-oxidation resistance of composites, ultrahigh temperature ceramics (UHTC) based coatings were prepared by slurry and chemical vapour deposition, then oxidation of samples was compared and their microstructures and mechanical properties were investigated. The results show that the oxidation of C–SiC without coating causes severe damage, and almost no carbon fibre is found in composites; the ZrC–SiC coated samples show better anti-oxidation performance at 1500°C; and the ZrB2–SiC coated samples show excellent anti-oxidation property at different oxidation temperatures. The UHTC based coatings can provide long time protection for C–SiC composites.