The high-temperature CMAS corrosion behavior of high-entropy (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Hf2O7 hafnate thermal barrier coating material with fluorite structure

High-temperature calcium-magnesium-alumina-silicate (CMAS) attack has become a fatal factor hindering the development of thermal barrier coatings (TBCs). In this study, a promising entropy-stabilized (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Hf2O7 (5LaH) hafnate was synthesized and prepared successfully, and then the CMAS corrosion behavior was investigated. During the corrosion process, the precipitation of the apatite phase causing the aggregation of Hf4+ promotes the formation of the (Hf, Si)O2 phase to generate a dense structure layer, which has a great barrier effect on the penetration of CMAS melt, and apatite phase with the entropy effect proves the stability of the reaction layer. Moreover, molten CMAS is less inclined to wetting and spreading on 5LaH surfaces compared to YSZ, which is also beneficial to the CMAS corrosion resistance. In general, the 5LaH exhibits great anti-CMAS corrosion performance.