Preparation and long-term ablation resistance of reaction-sintered Cf/SiBCN (Zr) composites

The C_f/SiBCN-ZrB₂ composites were prepared using an inorganic synthesis method - hot press reactive sintering. Three distinct composites were fabricated by combining reactive sintering with high-temperature melt infiltration, with the raw material ratios adjusted accordingly. A long-term ablation test lasting 400 s was performed using an oxy-acetylene flame, the surface temperatures of the samples exceeded 2100 °C. The absence of macroscopic cracks in all three samples indicates that the SiBCN composites, prepared via reactive sintering, exhibit excellent high-temperature stability. Among these, the composites with a higher silicon content, demonstrated the lowest ablation loss rate, with linear and mass ablation rates of 0.205 μm/s and 1.11 mg/s, respectively, significantly outperforming the composites with a reduced silicon content. The surface of the ablated samples, the continuous and dense ZrO₂-SiO₂ oxide layer, which serves as the main ablation barrier, effectively isolates the matrix from the oxy-acetylene flame.