A review on multicomponent rare earth silicate environmental barrier coatings

Rare earth (RE) silicate environmental barrier coatings (EBCs), with superior physicochemical properties and resistance to hot water-oxygen and calcium-magnesium-aluminosilicate (CMAS) corrosion, are ideal candidates for safeguarding the next-generation aviation engines made of SiC ceramic matrix composites (CMCs). However, improving the corrosion resistance of RE silicates remains a critical challenge due to severe environmental degradation at 1500 °C. Herein, by doping multiple RE elements and designing high entropy formulations, researchers found that multicomponent RE silicates could establish stable lattice structures, phase compositions, and reaction products while impeding the infiltration of corrosive agents. This paper reviews the modulation of their phase stability, physicochemical properties, wettability, and corrosion behaviors. It looks at how state-of-the-art optimization solutions of multicomponent and high entropy doping strategies affected corrosion resistant behaviors. In conclusion, the authors suggest further studies to optimize the corrosion resistance of multicomponent RE silicates and highlight the importance of integrating multicomponent doping with high-throughput and other optimization methods, thereby unlocking an array of possibilities for advancing RE silicate EBCs.