Ablative property of C/C-SiC-HfC composites prepared via precursor infiltration and pyrolysis under 3,000 °c oxyacetylene torch

C/C-SiC-HfC composites were fabricated via precursor infiltration and pyrolysis using a mixture solution of organic hafnium-containing polymer and polycarbosilane as precursor. The microstructures and the phases of the composites were analyzed by scanning electron microscopy and X-ray diffraction. The ablation resistance of the composites was evaluated under 3,000 °C oxyacetylene torch. After ablation for 120 s, the composites exhibit good ablation properties with the linear and mass ablation rates of 9.1 × 10^-4 mm/s and 1.30 × 10^-3 g/s, which are far lower than those of the C/C-SiC composites. The excellent ablative property of the C/C-SiC-HfC composites is resulted from the formation of HfO₂ molten layer on the surface of the composites, which could play a positive role in reducing heat transfer and preventing oxygen transport to the underlying carbon substrate.