Advanced anti-ablation ZrC–SiC modified C/C composites: Fiber selection and structural design strategies

Improving the ablation resistance of carbon/carbon (C/C) composites in high-temperature oxidative environments is critical to the effective design of thermal protection systems in aerospace applications. However, the exploration of the matrix ablation behavior of C/C composites has received limited attention in existing research. In this study, two types of 2.5D needle-punched preforms were designed through structural optimization for C/C composites, using mesophase-pitch-based carbon fiber (CF_MP) and polyacrylonitrile-based carbon fiber (CF_PAN) as reinforcements, respectively. Subsequently, 2.5D CF_MP/C–ZrC–SiC and 2.5D CF_PAN/C–ZrC–SiC composites, serving ZrC and SiC as the ablation-resistant ceramic phases, were fabricated via a combined process of chemical vapor infiltration (CVI) and precursor impregnation pyrolysis (PIP). Benefiting from the high thermal conductivity of CF_MP, 2.5D CF_MP/C–ZrC–SiC composites exhibited a thermal conductivity of 87.30 W/m*K at room temperature. Under high-temperature ablation conditions, its surface temperature was reduced by a maximum of 200 °C compared with that of 2.5D CF_PAN/C–ZrC–SiC composites. On this basis, a 3D CF_MP punctured preform was designed to further explore the effect of the preform structure on the ablation performance. The improvements in thermal conductivity and mechanical properties conferred by the 3D structure further enhanced the ablation resistance of CF_MP/C–ZrC–SiC composites. The composite exhibited linear and mass ablation rates of 1.983 μm/s and 1.776 mg/s, respectively, providing a valuable reference for the design of thermal protection systems for hypersonic vehicles and structural materials used in extreme environments.