Study on the propagation behavior of ablation-induced cracks in HfC-coated C/C composites by finite element numerical simulation

A combustion fluid-structure coupling model of O₂-C₂H₂ was established, and finite element simulation was employed to analyze the evolution law and interaction mechanism of HfC coating defects following oxygen acetylene ablation in this work. By conducting semi-quantitative simulations of the combustion reaction and flame erosion flow field, the distribution of various products in ablative flames on the surface of coated samples was obtained, thereby revealing the transition pattern of flame flow from vertical to horizontal direction. The results showed that the ablation morphology in different regions of HfC coated samples was determined by temperature, oxidation degree, and flame flow erosion behavior, which was consistent with the surface and cross-section images of the specimen after ablation. Moreover, vertically oriented cracks continued to propagate along their original surface and evolved into penetrating cracks, while inclined cracks tended to develop into inclined cracks or stepped cracks, which was supported by experimental results. Furthermore, the micropores had a promoting influence on crack growth, and there was a competitive effect among the pores of different positions and sizes in attracting cracks. This study provides theoretical guidance for further analyzing ablation defects and offers fundamental insights for improving the ablation resistance of coating.