Hot corrosion mechanism of yttria-stabilized zirconia powder in the presence of molten Na2SO4 + V2O5 salts

The hot corrosion behavior of yttria-stabilized zirconia (YSZ) powder specimens exposed to Na2SO4/V2O5 salts mixtures at high temperature was evaluated. Initial tests were carried out at 1000 degrees C for 10 h, the salt concentrations varied from 0.1 wt% to 1.00 wt%, and the Na2SO4/V2O5 mass ratios were between 0.20 and 0.44 following a factorial design 2(2). X-ray diffraction (XRD) analyses of the tested samples showed with a confidence of 95% that the mixture composed of 32 wt% Na2SO4 + 68 wt% V2O5, and 1.00 wt% salt concentration led to high destabilization of the t'-YSZ phase and formation of YVO4 products. A second set of experiments were conducted to assess the influence of temperature on the hot corrosion response of the YSZ in the range between 490 and 1100 degrees C. Thermogravimetric analysis (TGA) experiments and Rietveld adjustments of XRD patterns showed that the mass loss of the samples varied with testing temperature and also that the major destabilization of tetragonal phase occurred at 900 degrees C.