Anti-oxidation properties of ZrB2 modified silicon-based multilayer coating for carbon/carbon composites at high temperatures

To improve the anti-oxidation ability of silicon-based coating for carbon/carbon (C/C) composites at high temperatures, a ZrB₂ modified silicon-based multilayer oxidation protective coating was prepared by pack cementation. The phase composition, microstructure and oxidation resistance at 1773, 1873 and 1953 K in air were investigated. The prepared coating exhibits dense structure and good oxidation protective ability. Due to the formation of stable ZrSiO₄–SiO₂ compound, the coating can effectively protect C/C composites from oxidation at 1773 K for more than 550 h. The anti-oxidation performance decreases with the increase of oxidation temperature. The mass loss of coated sample is 2.44% after oxidation at 1953 K for 50 h, which is attributed to the decomposition of ZrSiO₄ and the volatilization of SiO₂ protection layer.