A novel lightweight HfB₂/ZrC/TiC modification Y₂Si₂O₇ fibrous porous ceramics with excellent ablation resistance

Lightweight ablative materials are essential for thermal protection systems of hypersonic vehicles, yet their poor ablation resistance under high heat flux, oxidizing environments limits further application. To reconcile the inherent trade-off between lightweight and ablation resistance, we propose a surface localized modification strategy: incorporating high emissivity, high melting point ceramic components only into the surface layer of Y₂Si₂O₇ fibrous porous ceramics via a simple vacuum impregnation technique. The dispersant concentration was optimized by sedimentation tests and ablation performance was evaluated on an oxyacetylene flame platform. The results show that the surface emissivity of the modified ceramics increases by 17.3%. After 120 s of ablation under a heat flux of 2.12 MW/m², the linear ablation rate decreases by 86.9% and is only 10.17 μm/s, and the surface temperature reaches approximately 1789 °C. A dense molten layer forms on the surface, which, together with the increased emissivity, effectively reduces surface temperature and suppresses further ablation. The proposed surface localized modification using high melting point ceramic components provides a versatile and effective route to significantly enhance the high temperature and ablation resistance of rigid thermal tiles without compromising their lightweight characteristic.