Theoretical design and experimental verification of high-entropy carbide ablative resistant coating

Composition design of high-entropy carbides is a topic of great scientific interest for the hot-end parts in the aerospace field. A novel theoretical method through an inverse composition design routine, i.e. initially ensuring the oxide scale with excellent anti-ablation stability, is proposed to improve the ablation resistance of the high-entropy carbide coatings. In this work, the (Hf0.36Zr0.24Ti0.1Sc0.1Y0.1La0.1)C1-δ (HEC) coatings were prepared by the inverse design method to investigate the ablation resistance. The linear ablation rate of the HEC coatings is -1.45 μm/s, only 4.78 % of the pristine HfC coatings after the oxyacetylene ablation at 4.18 MW/m2 for 40 s. The HEC possesses higher toughness with a higher Pugh’s ratio of 1.55 in comparison with HfC (1.30). The in-situ formed dense (Hf0.36Zr0.24Ti0.1Sc0.1Y0.1La0.1)O2-δ oxide scale during ablation benefits to improve the performance attributed to its high structural adaptability with a lattice constant changes not exceeding 0.19 % at 2000-2300 °C. The current investigation demonstrates the effectiveness of such inverse theoretical design, providing a novel approach for ablation protection of high-entropy carbide coatings.