Effects of HfC nanowire amount on the microstructure and ablation resistance of CVD-HfC coating

To improve the ablation resistance of HfC coating for carbon/carbon (C/C) composites, various fractions of HfC nanowires were incorporated into the HfC coating by chemical vapor deposition (CVD). Effects of HfC nanowire amount on the microstructure and ablation resistance of the CVD-HfC coating were investigated. Results indicated that the HfC nanowire layer became thicker and denser with the deposition time extending. HfC nanowires could inhibit the formation of cracks and interlaminar gaps in the HfC coating. With the increase of HfC nanowire amount, the HfC coating became thicker, while its porosity and roughness firstly decreased and then increased. Ablation tests indicated that the incorporation of HfC nanowires could effectively improve the ablation resistance of the HfC coating, which could be ascribed to the decreasing surface temperature of the coated samples and the effective alleviation of cracking and delamination of the coating during ablation. The HfC coating with HfC nanowires deposited for 1 h exhibited better ablation resistance owing to its compact microstructure, and its mass and linear ablation rates were only 0.41 mg/s and − 1.53 µm/s after ablation for 120 s.