A CrSi2-HfB2-SiC coating providing oxidation and ablation protection over 1973 K for SiC coated C/C composites

CrSi2-HfB2-SiC outer coatings were prepared on SiC coated C/C by in-situ reaction. The isothermal oxidation test at 1973 K and oxyacetylene flame ablation test were carried out to investigate oxidation and ablation resistance of the CrSi2-HfB2-SiC/SiC coated C/C samples, respectively. The coating with 15 wt.% Cr protected C/C for 415 h at 1973 K with a mass loss of 1.6 %. After ablation for 90 s, the coating was still intact, with slight increase in thickness and a mass ablation rate of only 4.56 x 10(-5) g/s. The Cr-Si-O and Hf-Si-O glasses have good stability and excellent oxidation and ablation protection.