Abstract:To improve the oxidation resistance of carbon/carbon composites, ZrB₂-MoSi₂/SiC coating on the carbon/carbon substrate was prepared. The inner coating of SiC was prepared by pack cementation and the outer coating of ZrB₂-MoSi₂ was prepared by slurry painting. The phase compositions and microstructures of the coating were characterized by XRD and SEM, respectively. The preparation and the high temperature oxidation property of the coated composites were investigated. The results show that the outer coating of carbon/carbon composites is composed of ZrB₂, MoSi₂ and SiC phases. The mass losses of the ZrB₂-MoSi₂/SiC coated samples with SiC nano-whiskers after 30 h and 10 h of oxidation at 1 273 K and 1 773 K were, respectively, 5.3% and 3.0%. The ZrB₂-MoSi₂/SiC coated samples exhibit self-sealing performance and good oxidation resistance at high temperature.

Key words: carbon/carbon composites; ZrB₂-MoSi₂; SiC; coating; oxidation