An oxidation protective coating prepared by SiC densifying HfB₂-SiC skeleton for SiC-coated C/C composites at 1473, 1773, and 1973 K

A HfB₂-SiC skeleton was designed on SiC-coated C/C composites using hollow SiO₂ microspheres as sacrificial templates, which was densified by SiC via chemical vapor infiltration to fabricate a dense SiC-HfB₂ oxidation protective coating. In this way, the uniform distribution of HfB₂ in the coating was realized. Cracks in the SiC inner coating were covered by the SiC-HfB₂ coating; Hf-oxides improved the stability and inhibited the volatilization of SiO₂ in the compound glass layer. Therefore, the coating can protect C/C composites against oxidation for 59 h at 1473 K, 503 h at 1773 K, and 166 h at 1973 K.