High-quality SiC-HfC coating with interpenetrating structure based on a two-step low temperature molten salt method

To improve the ablation resistance of carbon fibre (Cf), alleviate the interdiffusion between Cf and the matrix, and improve the complex preparation process of double-layer carbide coating, a high-quality SiC-HfC double interpenetrating coating was prepared on the surface of Cf using a molten salt synthesis (MSS) method. The microstructure, formation mechanism, and ablation behaviour of the coating were studied. The results show that the coating is composed of interpenetrating HfC and SiC phases. The interpenetrating structure was formed due to the transport of Hf ions into the interior of porous SiC nanowires facilitated by the molten salt medium, followed by diffusion through carbon. The SiC-HfC double-layer interpenetrating coating can serve as an oxygen barrier to protect Cf from oxidative damage under extreme temperature (2000 °C) and aerobic environment (oxyacetylene flame).