High-entropy (Ta_0.2Nb_0.2Ti_0.2Hf_0.2Zr_0.2)C-SiC ceramics: Achieving superior ablation resistance through SiC particle size optimization

To enhance ablation resistance in (Ta₀.₂Nb₀.₂Ti₀.₂Hf₀.₂Zr₀.₂)C–SiC (HEC–SiC) ceramics, the influence of SiC particle size on microstructure and ablation behavior was examined. With the addition of 20 wt% fine SiC particles, its relative density increases from 91.23 % to 97.79 %, and the grain size of the HEC phase decreased from 3.58 to 0.79 μm. The fine SiC particles facilitated the formation of a continuous SiC network, thereby enhancing the thermal conductivity from 6.94 to 22.35 W/mK. This enhanced thermal conductivity contributed to reducing the ablation temperature from 2358 to 1721 °C during the ablation. The HEC-SiC sample with 0.5 μm fine SiC particles added exhibits a mass and linear ablation rate of 0.05 mg/s and 0.67 µm/s. The superior ablation resistance can be attributed to the reduced ablation temperature, altering the preferential oxidation sequence. This change in preferential oxidation led to the formation of a compact oxide scale with a multi-layer structure.