Ablation performance of (C/C)/ZrB₂-SiC composites by different fabrication methods

The (C/C)/ZrB₂-SiC composites were prepared by slurry painting method and slurry impregnation method based on (C/C)/SiC composites. The ablation characteristics, phase composition and microstructure of the three kinds of composites were tested by oxyacetylene flame, SEM and EDS, respectively. The ablation mechanism was also investigated. The results indicate that compared with (C/C)/SiC composites, the (C/C)/ZrB₂-SiC composites show better ablation resistance properties. As to the uncoated (C/C)/SiC composites, the linear ablation rate of the (C/C)/ZrB₂-SiC composites is reduced by 33.3% and 15.4%, and the mass ablation rate reduces by 51.5% and 25.5% after ablation for 600 s and 1 000 s respectively, and the linear ablation rate of the micro-particle ZrB₂ impregnation composites is reduced by 20% and 28.8%, and the mass ablation rate reduces by 42.4% and 52.3% after ablation for 600 s and 1 000 s respectively. A ZrO₂-SiO₂ glassy melting layer formed at high temperature plays an important role in antioxidant and antierosion, which induces in better ablation resistance properties of the (C/C)/ZrB₂-SiC composites. The ablation mechanism is a synergistic effect of thermo-chemical ablation, thermo-physical ablation and mechanical erosion.