C/C composites are key thermal structural materials for hot-end components of aerospace vehicles. However, their susceptibility to oxidation and ablation at high temperatures limits their applications in extreme environments. Therefore, it is particularly important to improve the ablation resistance of C/C composites. The research progress of anti-ablation C/C composites at home and abroad in recent years are systematically reviewed, focusing on 3 aspects: matrix modification, coating protection, and matrix-coating integration. In terms of matrix modification, based on the differences in component characteristics, it is divided into single-phase ceramics, multiphase ceramics, multi-component and high-entropy ceramics modified C/C composites, revealing oxygen blocking and anti-ablation mechanisms of oxidation products of ceramics. The coating technology focuses on analyzing the design principles and ablation behaviors of single-layer coatings, multi-layer composite coatings with gradient structure, micro/nano structure toughened coatings, and coatings with embedded structure interface, clarifying the mechanisms of interface matching optimization in alleviating thermal mismatch of coatings and ablation behaviors. Finally, according to the application requirements for extreme ablation environments, the future development directions for C/C composites are proposed, including oxidation and ablation mechanism analysis, optimization of structure and composition of composite materials, functional design of components, and cost-effective fabrication processes.

HfC-SiC modified C/C composites containing in situ formed Si-HfC-HfSi₂ ablation resistant layer and SiC oxidation resistant layer were successfully prepared by reactive melt infiltration (RMI) combined with gaseous silicon infiltration (GSI). A comparative study was conducted on the anti-oxidation and anti-ablation performance of the C/C-HfC-SiC composites with GSI (noted as RG-CHS) and without GSI (noted as R-CHS). After oxidation at 1,500 ℃ for 200 min, the oxide film of RG-CHS remained intact. The mass and linear ablation rates decreased from 1.31 mg/s and 7.36 μm/s to 0.12 mg/s and −0.22 μm/s after GSI process, respectively. The introduction of low melting point phases and reducing surface defects can improve the high temperature oxidation resistance and plasma ablation resistance of the composites.

C/C-SiC-HfC composites were fabricated by using Precursor Infiltration and Pyrolysis (PIP) combined with Gaseous Silicon Infiltration (GSI) process. Different GSI temperatures (1900 ℃ and 2100 ℃) were selected. The combination of PIP and GSI could significantly reduce the preparation time of the composites. The morphology displaying a rich-Si layer was formed on the surface of the composites prepared at GSI 2100 ℃. Ablation performance of the composites was investigated by oxyacetylene torch. The results showed that after ablation for 120 s, compared to the composites prepared by PIP + 1900 ℃ GSI, the linear and mass ablation rates of the composites fabricated by PIP + 2100 ℃ GSI were decreased from 8.05 μm/s to 5.06 μm/s and from 1.61 mg/s to 1.03 mg/s, respectively. The coverage of the rich-Si surface layer promoted the generation of more SiO₂ during ablation, which not only benefited for decreasing the surface temperature but also contributed to the formation of H-Si-O glass and the HfO₂ skeleton, thus better resisting the denudation of the oxyacetylene torch.