Enhancing the ablation resistance of C/C-HfC-ZrC-SiC composites via a molten-salt-deposited TiC coating

To enhance the ablation resistance of C/C-HfC-ZrC-SiC composites at temperatures above 2100 °C, a TiC coating was deposited on the surface of the composites by the molten salt method to achieve pore sealing. The influence of this coating on the ablation behavior of the composites was systematically investigated. When exposed to an oxygen-acetylene flame of 2.4 MW/m 2 for 60 s, the mass ablation rate and linear ablation rate of the TiC-coated composite were only 1.12 mg/s and 0.51 μm/s, respectively. Compared with the uncoated samples (1.64 mg/s and 1.05 μm/s), they were reduced by 32% and 51%, respectively. The excellent ablation resistance can be attributed to the preferential oxidation of the TiC coating to form a continuous liquid TiO 2 layer. This liquid layer significantly reduces the surface heat load through evaporation and heat absorption, lowering the surface ablation temperature by approximately 70 °C. Additionally, the liquid TiO 2 penetrates into the interior of the oxide scale through capillary action and reacts with HfO 2 and ZrO 2 in the matrix, promoting in-situ sintering and forming a dense (HfZrTi)O 2 composite oxide scale with a thickness of approximately 100 μm. The synergistic effect of physical sealing and chemical reaction between the coating and the substrate helps to form a robust self-healing oxide scale, providing effective protection under extreme thermal conditions.