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 hat 1473 K, 503 hat 1773 K, and 166 h at 1973 K.

Automated summary

A HfB2-SiC skeleton was designed using hollow SiO2 microspheres as sacrificial templates on SiC-coated C/C composites. The skeleton was densified by SiC via chemical vapor infiltration to fabricate a dense SiC-HfB2 oxidation protective coating. The uniform distribution of HfB2 in the coating enhanced its effectiveness in covering cracks in the SiC inner coating. Hf-oxides contributed to the stability and inhibition of SiO2 volatilization in the compound glass layer. The coating exhibited excellent oxidation protection for C/C composites under high temperatures.