Hot corrosion behavior of TiO2 doped, Yb2O3 stabilized zirconia exposed to V2O5 + Na2SO4 molten salt at 700-1000 °C

3.5 mol% Yb2O3 stabilized zirconia (YbSZ) doped with 10 mol% TiO2 (Ti-YbSZ) was produced, and its hot corrosion behavior exposed to Na2SO4 + V2O5 molten salt was investigated. The as-fabricated ceramic mainly consists of metastable tetragonal (t′) phase. When exposed to the molten salt at 700 °C, 800 °C, 900 °C and 1000 °C for 2 h and 10 h, YbVO4 and m-ZrO2 formed as corrosion products due to chemical reactions between the ceramics and the salt. Ti4+ in Ti-YbSZ solid solution keeps stable during the hot corrosion tests, which acts as a stabilizer for ZrO2, preventing total decomposition of the t′ phase. After the hot corrosion tests, Ti-YbSZ has an apparently lower m phase content than Y2O3 doped Zirconia and YbSZ, indicative of better corrosion resistance. The hot corrosion mechanism of Ti-YbSZ is proposed based on Lewis acid-base rule, phase diagrams and thermodynamics.