Mo-Si-B based coating for oxidation protection of SiC-C composites


Silicon carbide conversion coated carbon/carbon composites (SiC-C) are promising materials for high temperature engine, aircraft and aerospace applications. However, the inherent coating cracks in SiC-C composites due to processing and rapid degradation of silica and SiC in corrosive combustion environments demand a protective external coating to preserve the integrity of the material during service. The Mo-Si-B based coating has been shown to be robust in oxidative environments at extreme temperature, making it an attractive candidate to protect SiC-C composites from oxidation. Isothermal oxidation behavior of Mo-Si-B coated SiC-C was studied and compared to uncoated SiC-C composites at 1073K and 1773K in ambient air. The Mo-Si-B based coating effectively protected the SiC-C composite with minimal weight lost due to the formation of a protective and continuous aluminoborosilica surface layer. Exposed carbon fibers in the uncoated SiC-C composites led to catastrophic oxidation. Thermogravimetric analysis of an uncoated SiC-C composite at 1588K confirmed the accelerated rate at which the carbon fibers oxidized to leave a brittle SiO 2 skeleton. The same analysis on Mo-Si-B coated SiC-C showed nearly negligible steady state weight loss. The initial evaluation provides clear evidence that the Mo-Si-B based coating serves as a robust and compatible coating for SiC-C composites over a wide temperature range.

Document Type




Ceramic matrix composites, Mo-Si-B based coating, Oxidation protection, SiC

Publication Date


Journal Title

Surface and Coatings Technology