SiC-MoSi₂/ZrO₂-MoSi₂ coating to protect C/C composites against oxidation

To improve the oxidation resistance of carbon/carbon (C/C) composites in air at high temperatures, a SiC-MoSi₂/ZrO₂-MoSi ₂ coating was prepared on the surface of C/C composites by pack cementation and slurry method. The microstructures and phase compositions of the coated C/C composites were analyzed by scanning electron microscopy and X-ray diffraction, respectively. The result shows that the SiC-MoSi ₂/ZrO₂-MoSi₂ coating is dense and crack-free with a thickness of 250-300 μm. The preparation and the high temperature oxidation property of the coated composites were investigated. The as-received coating has excellent oxidation protection ability and can protect C/C composites from oxidation for 260 h at 1773 K in air. The excellent anti-oxidation performance of the coating is considered to come from the formation of ZrSiO₄, which improves the stability of the coating at high temperatures.