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 °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 2². 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 °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 °C.