Effect of Calcium–magnesium–aluminum Silicate Composition on Reaction Behavior for X1‐Gd2SiO5 and X2‐Er2SiO5 Environmental Barrier Coatings

Rare-earth (RE) silicates environmental barrier coatings (EBCs) are prone to accelerate failure resulted from molten calcium-magnesium-aluminum silicate (CMAS), which presents significant challenges to the design and development of durable EBCs. In this study, X1-Gd2SiO5 and X2-Er2SiO5 coatings were explored on their corrosion resistance to CMAS melts with different Ca/Si ratios (1.1, 0.75, 0.64, and 0.42) at 1350degree celsius for 25 and 50 h, respectively. Results showed that with the Ca/Si ratio increasing, CMAS viscosity decreased and a more intense corrosion reaction with coatings occurred. Garnet phase was only observed in X2-Er2SiO5 coating corroded by CMAS with high Ca/Si ratios, which could be beneficial for improving corrosion resistance. The X2-Er2SiO5 phase, which is composed of [SO4] and [REO6]/[REO7] polyhedrons, exhibits better corrosion resistance due to its more stable crystal structure, lower reactivity with CMAS, and the radius difference between the RE ions and Ca2+.