C/C-HfC-ZrC composites with excellent long-term ablation performance prepared by combining PIP and RMI

C/C-HfC-ZrC (noted as CHZ) composites were prepared by a combined technique of polymer infiltration and pyrolysis (PIP) and reactive melt infiltration (RMI) to resist long-term ablation. The phase composition, microstructure and ablation properties of the composites were studied. Moderate HfC introduced by PIP cooperated with ZrC generated during RMI improved the ablation resistance of CHZ significantly, whose mass and linear ablation rates were only 0.544 mg/s and 0.107 μm/s, respectively, after ablation for 600 s (15 × 40 s) using oxyacetylene flame with a heat flux of 4.18 MW/m². The excellent long-term ablation performance was attributed to the formation of a HfO₂-ZrO₂ solid solution layer, which resisted the flame scouring and prevented the oxygen permeation. This work will provide some insight into long-term anti-ablation design and the combination of multiple techniques.