Nickel-based superalloy DZ125 was first sprayed with a NiCrAlY bond coat and followed with a nanostructured 2 mol% Gd2O3-4.5 mol% Y2 O3-ZrO2（2 GdYSZ） topcoat using air plasma spraying（APS）. Hot corrosion behavior of the as-sprayed thermal barrier coatings（TBCs） were investigated in the presence of 50 wt%Na2SO4 + 50 wt% V2O5 as the corrosive molten salt at 900 ℃ for 100 h. The analysis results indicate that Gd doped YVO4 and m-ZrO2 crystals were formed as corrosion products due to the reaction of the corrosive salts with stabilizers（Y2O3, Gd2O3） of zirconia. Cross-section morphology shows that a thin layer called TGO was formed at the bond coat/topcoat interface. After hot corrosion test, the proportion of m-ZrO2 phase in nanostructured 2GdYSZ coating is lower than that of nano-YSZ coating. The result reveals that nanostructured 2GdYSZ coating exhibits a better hot corrosion resistance than nano-YSZ coating.
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