Microstructure evolution and ablation behavior of C/C-HfC-ZrC-SiC composites in extreme laser ablation environment

To balance the excellent protection performance, lightweight design and low preparation cost of carbon-based composites for extreme high-temperature environment, the C/C-HfC-ZrC-SiC composites with varying Hf/Zr molar ratios via reactive melt infiltration were optimized under high-energy laser ablation condition (39.8 MW/m²). Combined with ablation recession simulations, the increase in Hf/Zr ratio facilitates the improvement of the laser ablation resistance, while the performance enhancement effect at 40 s ablation is not apparent. The higher structural stability of (Hf,Zr)O₂ solid solution enhances the ablation resistance of the equimolar Hf/Zr ratio composites, with the linear variation rate of only 3.83 μm/s. The thermal stress mismatch between the carbon fiber bundles and the ceramic-rich layer is susceptible to crack initiation and extension, resulting in destructive sublimation and oxidation. In consideration of the overall density, ablation performance and cost, the equimolar Hf/Zr ratio composites exhibit the best performance during laser ablation.