Preparation and anti-oxidation property of SiC/SiC-MoSi₂ coating on C/C composite

To protect carbon/carbon (C/C) composites against oxidation at high temperature, SiC inner layer and SiC-MoSi₂ multi-layer outer coatings were prepared on the surface of C/C composites by a two-step technique of pack cementation and slurry coating. The microstructure of the as-received coating was analyzed by XRD and SEM. The oxidation behaviors of the coated samples at high temperatures in air were studied by isothermal oxidation tests. The results show that the as-received multi-layer SiC/SiC-MoSi₂ coating posseses a crack-free structure and excellent oxidation resistance, which could protect C/C composites from oxidation in air for more than 110 h at 1500°C and for more than 100 h at 900°C. Excellent anti-oxidation ability of the SiC/SiC-MoSi₂ coating is attributed to its multi-layer and multi-phase structure and the formation of protective SiO₂ film on its surface during oxidizing.