Rare earth silicate in SiC_f/SiC composites: Toward water‒oxygen corrosion resistance in high-temperature gas environment

Silicon carbide fiber-reinforced silicon carbide ceramic matrix (SiC_f/SiC) composites are considered as one of the preferred materials for aero-engine hot-end components; however, they will face serious performance degradation when exposed to the complex and harsh environment of high temperature and water‒oxygen corrosion coupling. How to solve the problem of SiC_f/SiC composites is a growing concern in the international community. Rare earth silicate materials usually have the advantages of good high-temperature stability, low oxygen permeability constant, and thermal expansion coefficient matching with SiC, which are internationally recognized as the preferred systems for the new generation of environmental barrier coatings (EBCs); meanwhile, the use of rare earth compounds for matrix modification of SiC_f/SiC composites to improve their resistance to water‒oxygen corrosion has gained wide attention. Therefore, the recent progress in rare earth silicate EBCs and modified SiC_f/SiC composites are reviewed. Finally, the challenges and prospects of rare earth silicate in improving the water‒oxygen corrosion resistance of SiC_f/SiC composites are presented.