Hot-corrosion behavior of Y₂O₃-doped lanthanum cerate thermal barrier coatings in sulfate–vanadate molten salts

In this study, the hot-corrosion behavior of Y₂O₃-doped La₂Ce₂O₇, namely (La₁.₆Y₀.₄)₂Ce₂O₇ (LYC), was systematically investigated. For this purpose, YSZ/LYC double-layer coatings incorporating an intermediate YSZ layer were deposited on Hastelloy X substrates with a NiCrAlY bond coat by atmospheric plasma spraying (APS), while a conventional single-layer YSZ coating was prepared for comparison. The YSZ coating underwent complete delamination after 100 h, accompanied by YVO₄ and monoclinic ZrO₂ formation, indicating severe degradation associated with phase transformation and chemical interaction with the molten salt. In contrast, the YSZ/LYC double-layer coating demonstrated significantly improved hot-corrosion resistance under identical conditions. LaVO₄ was identified as the predominant corrosion product in the LYC layer, accompanied by minor YVO₄ and CeO₂ phases, with LaVO₄ exhibiting a bar-shaped morphology and CeO₂ appearing as cuboidal particles on the hot-corroded surface. These findings demonstrate that the YSZ/LYC double-layer coating exhibits improved hot-corrosion resistance compared with conventional YSZ, associated with the distinct corrosion-product formation and phase evolution of the YSZ and LYC layers during molten-salt exposure.