Process optimization and ablation performance of C_f/ZrB₂‒SiC composites prepared by slurry injection combined with RMI

In response to the urgent demand for ablation resistance and cost-effective thermal protection materials for hypersonic vehicles, this study employed a combined process of slurry injection and reactive melt infiltration to rapidly fabricate C_f/ZrB₂‒SiC composites. The effects of infiltration temperature (1450°C‒1600°C) and holding time (0.5‒2.0 h) on the microstructure and mechanical properties were systematically investigated. Results demonstrate that at 1500°C, the competition mechanism between molten Si viscosity and reaction rate was balanced, achieving efficient pore filling. Composites processed at 1500°C for 1 h exhibited optimal mechanical properties, with a flexural strength of 234.08 MPa. As the holding time increased, elemental homogeneity improved in the matrix while mechanical properties decreased. The oxyacetylene ablation test (4.18 MW/m²) showed: at 100 s, a dense ZrO₂‒SiO₂ oxide layer formed, resulting in ablation rates of 0.32 mg/s and 0.70 µm/s. After 300 s, thermal stress caused oxide layer spallation, elevating rates to 2.90 mg/s and 4.50 µm/s, triggering a new ablation cycle. The material demonstrates exceptional ablation resistance. This process provides a valuable reference for the low-cost fabrication of high-performance ultra-high temperature ceramic matrix composites.