Design of ablation resistant Zr-Ta-O-C composite coating for service above 2400 ℃

To improve the limited ablation resistance of Zr-Ta-O compound film induced by Ta continuous enrichment, phase diagram design and ablation tests (4.2 MW/m 2 ) were conducted to obtain an appropriate modification strategy. The Zr 6 Ta 2 O 17 intermediate phase was synthesized and introduced into plasma sprayed ZrC coatings. Compared with ZrC coating, the linear variation rate of ZrC-5 vol% Zr 6 Ta 2 O 17 coating was decreased by 80%. The greatly improved ablation performance was attributed to the weakening effect of minor Ta solid solution on the Zr-O covalent bond and appropriate addition amount of Zr 6 Ta 2 O 17 phase to keep Ta/Zr molar ratio under a low level (Ta/Zr < 1/11). • Zr 6 Ta 2 O 17 powder was successfully synthesized by solid phase diffusion method. • Plasma sprayed ZrC-Zr 6 Ta 2 O 17 coatings were prepared to study Zr-Ta-O compound film. • After 5 vol% Zr 6 Ta 2 O 17 addition, the linear ablation rate exhibited 80% decline. • Low Ta/Zr molar ratio (< 1/11) helped improve temperature resistance of Zr-Ta-O layer.