Preparation, ablation behavior and thermal retardant ability of C/C-HfB₂-SiC composites

C/C-HfB₂-SiC composites were prepared by precursor infiltration and pyrolysis followed by reactive melt infiltration. Thermogravimetric analysis showed that C/C-HfB₂-SiC composites possessed better oxidation resistance than that of C/C composites. Ablation behavior and thermal retardant ability of C/C-HfB₂-SiC composites were investigated using oxyacetylene torch. Compared with C/C, thermal retardant ability of C/C-HfB₂-SiC composites was improved by 80.45%, which was 406 °C/mm. After ablation for 90 s, the linear and mass ablation rates of C/C-HfB₂-SiC composites were reduced by 73.59% and 77.84%, which were 2.06 μm·s^− 1 and 0.129 mg·cm^− 2·s^− 1, respectively. Two typical morphologies of HfO₂ skeleton layer and borosilicate glassy layer were formed after ablation, which were indicated to be beneficial for the improvement of thermal retardant ability and ablation performance.