Ablation behaviors and mechanism of ZrC-SiC-Si/SiC-Si double-layered coatings on C/C composite under plasma flame at 3000 °C

To improve the ablation performance of C/C composite at 3000 °C, a ZrC-SiC-Si/SiC-Si double-layered coatings (ZSS/SS) was prepared by slurry dipping-carbonization and gaseous silicon infiltration. During ablation, a competition between mechanical denudation and oxidation derived thickening occurred. The ZSS/SS coating possessed a superior ablation resistance showing lowest linear ablation rate of 0.53 µm/s in 90 s with a parabolic rate constant K_p (0.053 µm/s³). The excellent performance was attributed to good self-sealing of oxidation derived glassy, thus no micro-cracks were observed. However, the K_p became worse to be 0.131 for long-term ablation because of dominant mechanical denudation.