Elemental synergistic effect for enhancing ablation resistance of Zr1/2Hf1/3Ti1/12Ta1/12C ceramic

Abstract

Formation of multicomponent ceramics is one of the most promising strategies for enhancing the ablation resistance of ultra-high-temperature carbide ceramics (UHTCCs), while the effects of the elements are the foundation. Here, we reported an elemental synergistic effect by investigating the ablation behavior of three components, including Zr_1/2Hf_1/3Ti_1/6C (ZHTi), Zr_1/2Hf_1/3Ta_1/6C (ZHTa), and Zr_1/2Hf_1/3Ti_1/12Ta_1/12C (ZHTT). Results indicate that the Ti-Ta synergistic effect enables ZHTT to exhibit a low recession rate (3.33 ​μm/s) and linear expansion rate (2.00 ​μm/s) of its oxide layer, attributable to enhanced self-healing capability and durable protection. During ablation, outward diffusion of Ti can heal the oxide layer, but results in severe consumption of UHTCCs. Although the low-volatility oxide formed by Ta can reduce the loss rate of the matrix, the negligible outward diffusion of Ta leads to the formation of a porous outer oxide layer. The co-addition of Ti and Ta simultaneously provides effective self-healing and low matrix recession, enabling enhanced ablation resistance of ZHTT.