Interactions Between Sc2O3 Ceramics and Calcium–Magnesium–Alumina–Silicate (CMAS) at Elevated Temperature

The thermochemical interactions of Sc2O3 ceramics with CMAS at 1250 °C and 1300 °C were investigated in this paper. A continuously dense reaction layer (DRL) forms on the surface of the ceramic at the beginning of the reaction within 15 min, and temperature significantly affects the components of the DRL. The DRL is mainly composed of a diopside phase at 1250 °C, whose thickness decreases with reaction time, while it is composed of garnet and minor diopside phases at 1300 °C, and thickens in accordance with the parabolic law with exposure time. The DRL shows good effect on alleviating Mg2+ infiltration and some mitigating effect to Al3+, and relatively inferior resistance to Ca2+ and Si4+ penetration. The concentration of Sc3+ in the residual CMAS increases with reaction temperature and time, and the average contents are about 0.7 at% and 3.7 at% after reactions at 1250 °C and 1300 °C, respectively. The mechanism is discussed systematically.