Oxidation behavior of C/SiC composites with a SiC/Mo-Si multilayer coating

A SiC/Mo-Si multilayer coating was prepared on the surface of C/SiC composites by chemical vapor deposition (CVD) combined with slurry painting. The coating was composed of a dense CVD SiC coating alternating with a porous MoSi layer. From inside to outside the coating consisted of CVD SiC, Mo-Si, CVD SiC, Mo-Si and CVD SiC . The coating remained intact and no obvious failure such as destruction or spalling was found during oxidation at 1400℃ and thermal shock between 1400℃ and room temperature. The mass loss and mass loss rate of the coated sample were only 0.25% and 6.61×10^-6g · cm^-2 · h^-1, respectively after oxidation at 1400℃ for 150h. The flexural strength retention was 95.73％ and 81.61％ after 25 and 50 thermal cycles respectively and mass of the coating generally increased after oxidation. The SiC/Mo-Si multilayer coating showed excellent antioxidation ability and a thermal shock resistance and could effectively protect the C/SiC composites at 1400℃ for a long time.