Investigation on the oxidation and ablation behaviors of HfB2-SiC-Si/SiC-Si coatings for carbon/carbon composites

Oxidation and ablation behaviors of HfB2-SiC-Si/SiC-Si coatings fabricated by dipping-carbonization joint gaseous silicon infiltration on cubic and nose-shaped carbon/carbon substrates were investigated. After 30 thermal cycles between 1500 degrees C and room temperature, the mass gain of the coated sample was 0.91 %, and the mass gain was 2.62 % after oxidation at 1500 degrees C for 870 h. The coated nose-shaped sample exhibited good antiablation properties at 1800 degrees C-2000 degrees C under oxyacetylene flame. Especially at 1800 degrees C, the mass ablation rate was -0.073 mg/s. Although the nose tip suffered the most serious corrosion, HfO2 scale surrounded by Hf-Si-O glass could withstand the oxyacetylene torch scouring.

Automated summary

The study investigated the oxidation and ablation behaviors of HfB2-SiC-Si/SiC-Si coatings under high temperatures, showing that the coatings exhibited good anti-ablation properties at 1800 degrees Celsius. Despite the severe corrosion at the nose tip, the protective layer composed of HfO2 and Hf-Si-O glass in the coating could withstand the scouring of the oxyacetylene torch.