Hot corrosion behavior of (Gd0.9Sc0.1)2Zr2O7 in V2O5 molten salt at 700–1000 °C

Hot corrosion behavior of (Gd0.9Sc0.1)2Zr2O7 ceramic exposed to V2O5 molten salt at 700–1000°C was investigated, providing better understanding of its corrosion resistance as a promising thermal barrier coating. Obvious corrosion reaction occurred between (Gd0.9Sc0.1)2Zr2O7 and V2O5 molten salt after 4h heat treatment, corrosion products being temperature dependent. At 700°C, large amount of Sc2O3 doped ZrV2O7 and GdVO4, together with a minor amount of Sc2O3-stabilized tetragonal ZrO2 (t-ZrO2), formed on the sample surfaces. With the increase of the test temperature, Sc2O3 doped ZrV2O7 turned to decompose, leading to the formation of more t-ZrO2. At 900°C and 1000°C, the corrosion products were composed of GdVO4 and t-ZrO2. The mechanism by which the corrosion reaction occurs is proposed based on phase diagrams and Lewis acid-base rule.