The corrosion behavior of Sc2O3-Y2O3 co-doped ZrO2 influenced by Sc2O3 content in CMAS at 1300 °C

The effect of Sc2O3 content on the corrosion behaviors of xSc2O3-3.5Y2O3 co-doped ZrO2 (ScYSZ, x = 4.5, 5.5 and 6.5 mol.%) in calcium-magnesium-alumino-silicate (CMAS) at 1300 degrees C was investigated in this paper. It is shown that the ScYSZ ceramic exhibits better resistance to molten CMAS attack when doping with more Sc2O3. The CMAS penetration depth in the ScYSZ ceramic decreases with increasing Sc2O3. It is about 18 mu m of CMAS penetrated depth in the 6.5Sc3.5YSZ after corrosion for 4 h at 1300 degrees C, including an 11 mu m and 7 mu m for the reaction-reprecipitation and grain-boundary infiltration layers, respectively. High thermochemical stability and weak reactivity of the ScYSZ to the glassy CMAS melt are beneficial to enhance the high temperature corrosion resistance, attributing to the low solubility in molten CMAS and the weak affinity to Ca2+ for small ionic radius Sc3+. The mechanism of enhancing the resistance to CMAS is discussed.