Long-time ablation behavior of the multilayer alternating CVD-(SiC/HfC)₃ coating for carbon/carbon composites

To improve the service life of carbon/carbon (C/C) composites under ultra-high temperature ablation environments (> 2200 ℃), SiC/HfC coating with multi-layer alternating structure was designed and prepared on C/C composites by low-pressure chemical vapor deposition (LPCVD). The microstructure and phase compositions of the as-prepared and ablated coatings were investigated, and the influence of the multi-layer structure on the ablation behavior and thermal stress distribution of the coatings were analyzed as well. After ablation for 120 s, the (SiC/HfC)₃ coating has better ablation resistance due to its multi-layer structure and the formation of Hf-Si-O sticky glass phase.