Functionally graded oxide structures in coating-matrix integrated C/C-ZrC-SiC composites for synergistic ablation protection

A novel method combining chemical liquid-vapor infiltration (CLVI) for controlled porosity in C/C-ZrC-SiC composites with reactive melt infiltration (RMI) for ceramic introduction was developed. Additionally, the CLVI-derived pyrolytic carbon and ceramic phases effectively mitigate RMI-induced corrosion while enabling the fabrication of coating-matrix integrated C/C-ZrC-SiC composites. During 60-s ablation with a 2.4-MW/m 2 heat flux, the composites formed a dense ZrO 2 layer that effectively prevents inward oxygen diffusion and resists flame scouring, demonstrating better ablation resistance. Remarkably, in cyclic ablation tests with a 4.2-MW/m 2 heat flux (3×30 s), the composites achieve near-zero ablation rates (mass: -0.47 mg/s; linear: -0.38 μm/s). The excellent ablation performance resulted from functionally graded oxide structures, featuring an outer ZrO 2 layer and an inner ZrO 2 -SiO 2 layer that synergistically reduced thermal conduction and alleviated interfacial stress concentration. The results reveal a transition in the ablation failure mechanism from thermochemical reactions to mechanical erosion. This study provides fundamental insights into coating-matrix synergies, guiding the structural design of ultra-high temperature ceramics modified C/C composites for extreme environments.