Work

Tailoring ablation resistance of (Hf,Zr,Ta)C coatings above 2000 °C: Critical role of Ta content

Year: 2024

Type: article

Abstract: Multi-component (Hf,Zr,Ta)C ceramics are promising candidates for ablation-resistant coating materials applied in ultra-high temperature environments. However, the influence of compositional variations on their ablation behavior remains insufficiently understood. In this study, the effect of Ta content on the ablation resistance of (Hf,Zr,Ta)C coatings were systematically investigated. Moderate Ta addition promotes the densification of oxide scales, while excessive Ta reduces the thermochemical stability of the oxide, leading to increased ablation damage. The optimized composition, (Hf0.425Zr0.425Ta0.15)C, exhibited superior ablation resistance, maintaining structural integrity for 300 s under ~2160 °C oxyacetylene flame. This enhancement is attributed to the co-formation of (Hf,Zr,Ta)O2 and (Hf,Zr)6Ta2O17 phases. Ta5+ partially dissolves into (Hf,Zr)O2 (~5 at.%), reducing oxygen vacancy concentration and improving oxidation resistance. Additionally, the Ta-rich liquid phase generated from (Hf,Zr)6Ta2O17 decomposition enhances oxide scale densification and contributes to structural stability during cooling via peritectic transformation. These results demonstrate that non-equimolar multi-component carbides offer a feasible strategy for improving the ablation resistance of ultra-high temperature coatings.

Source: Journal of Advanced Ceramics

DOI: 10.26599/jac.2025.9221207