Ablation behavior of medium entropy carbide ceramics with different molar ratios of (Hf, Zr, Ti)C in oxyacetylene flame

(Hf_1/3Zr_1/3Ti_1/3)C and (Hf_1/2Zr_1/3Ti_1/6)C middle-entropy carbide ceramics were successfully prepared using polymer-derived ceramic method. The study examines the microstructural evolution, phase composition changes, and ablation behavior of these two ceramic materials when subjected to an oxyacetylene flame at varying heat fluxes. The experimental results indicate that at a heat flux of 5 MW/m², the mass and linear ablation rates of (Hf_1/3Zr_1/3Ti_1/3)C ceramic are −0.837 mg/s and 1.857 μm/s, respectively. In contrast, (Hf_1/2Zr_1/3Ti_1/6)C ceramic exhibits significantly superior ablation resistance, with rates of −0.315 mg/s and −0.745 μm/s. This underscores the critical role of compositional adjustments in enhancing the ablation performance of the ceramic. During ablation, (Hf_1/2Zr_1/3Ti_1/6)C forms an optimal amount of (Hf, Zr)TiO₄ healing phase, which contributes to the development of a stable oxide film consisting of an m-(Hf, Zr, Ti)O₂ oxide skeleton and a (Hf, Zr)TiO₄ liquid phase. This structure effectively resists high-velocity airflow erosion and oxygen penetration. Additionally, the formation of a carbonaceous oxide interlayer strengthens the bond between the oxide layer and the carbide matrix, further improving the material's ablation resistance. The study highlights the significant influence of compositional ratio control on the ablation behavior and mechanisms of carbide ceramics, providing a robust foundation for their application in high-temperature thermal protection technologies.