Effect of pore structure optimization on microstructure evolution and ablation performance of C/C-SiC-ZrC composites fabricated by reactive melt infiltration

The pore structure of C/C preforms is a critical factor determining the microstructure and properties of composites prepared by reactive melt infiltration (RMI). This study used chemical vapor infiltration (CVI) and slurry infiltration (SI) processes to optimize the pore characteristics of C/C preforms. C/C-SiC-ZrC composites were fabricated via RMI, and the effects of pore structure optimization on microstructure, ablation performance, and flexural properties were investigated. Results showed the SI-optimized sample performed best: mass and linear ablation rates decreased to 0.44 ± 0.01 mg/s and −0.49 ± 0.01 μm/s, respectively, representing reductions of 90.29% and 88.89% versus non-optimized samples, and 83.76% and 84.88% versus CVI-optimized samples. Flexural strength increased by 32.93% versus non-optimized samples. The improvement is mainly due to a dual-protection structure in the SI-optimized sample matrix: a “continuous and dense ZrC-SiC ceramic skeleton” and a “ZrC anti-oxidation interphase”.