Effect of Gd2O3 Addition on the Growth Behavior of the Dense Reaction Layer at the Interface Between Al2O3 Ceramic and CMAS at 1300 °C

HighlightsWhat are the main findings?•The dense double reaction layer of anorthite–spinel exhibits a positive effect on inhibiting the infiltration of calcium–magnesium–aluminum-silicate.•The thickness of the reaction layer increases with reaction time, while the growth rate rapidly decreases.•More Gd2O3doping enhances the outward diffusion of Gd3+and promotes the crystallization of the CMAS and apatite phases.•The inward infiltration of CMAS and outward diffusion of Al3+and Gd3+along the grain boundaries of the anorthite and/or spinel phases thicken the reaction layers.What are the implications of the main findings?•They clarify the reaction mechanism between Al2O3-based ceramics and CMAS in a high-temperature environment.•Doping with rare-earth Gd2O3can serve as an effective strategy for enhancing the CMAS corrosion resistance of Al2O3-based ceramics.•This study provides valuable reference guidance for the compositional design and research development of CMAS corrosion-resistant materials.The exploration of new materials with stable molten calcium–magnesium–aluminum-silicate (CMAS) resistance at elevated temperatures is of great significance to the development of advanced aero-engines. In the present study, Al2O3−xGd2O3(x = 5, 10, 20, 30 mol.%) ceramic samples were prepared by the high-temperature solid-state synthesis method. The thermochemical reaction behavior, reaction products, and growth kinetics of the reaction layer for the ceramics with molten CMAS at 1300 °C were investigated. The results reveal that the primary reaction products between Al2O3−xGd2O3ceramics and molten CMAS are anorthite (CaAl2Si2O8), gehlenite (Ca2Al(AlSi)O7), spinel (MgAl2O4), and Gd-apatite (Ca2Gd8(SiO4)6O2). In the initial reaction stage, a dense double-layer reaction layer composed of anorthite and spinel is formed at the ceramic/CMAS interface, while its growth rate decreases with increasing reaction time. Increasing the Gd2O3doping content inhibits the growth of the reaction layer and enhances the CMAS penetration resistance of Al2O3−xGd2O3ceramics. The mechanism is discussed systematically.