ZrC, HfC, and ZrC/ZrxSiy coatings prepared via molten salt Solid–Liquid two-phase diffusion method and ablation properties

ZrC, HfC, and ZrC/Zr x Si y composite ceramic coatings were prepared on the surface of carbon-matrix composites via molten salt solid–liquid two-phase diffusion to improve the ablation resistance of the C/C composites. The preparation of the coating composition could be controlled by using different powders. The effects of temperature and holding time on the microstructures of ZrC coatings and their variation laws were studied. Results showed that the ZrC coating density increased with temperature and holding time. At a holding time of 16 h, the growth of the ZrC coating was slow. The volatilization of SiO 2 caused loose ZrO 2 to splash. Moreover, the Si content was found to affect the ablation performance of the ZrC/Zr x Si y composite ceramic coatings, and the ablation mechanism was studied. The ZrC, HfC, and ZrC/Zr x Si y composite ceramic coatings exhibited good ablation properties. The ablation rates of the ZrC and HfC coatings were 0.805 and 0.715 mg/s, respectively, after oxyacetylene flame ablation at 3000 °C for 60 s.