Abstract:Excellent water vapor corrosion resistance is critical for the selection and design of environmental barrier coatings (EBCs). Rare-earth silicates, as ideal top-layer materials for EBCs, tend to develop penetration cracks under water vapor corrosion environments, which further accelerate the oxidative cracking of the Si bond layer and lead to failure of EBCs. MoSi2 exhibits outstanding high-temperature properties, and its incorporation into rare-earth silicates materials is expected to mitigating crack propagation and oxidation cracking issues during EBCs service. In this work, vacuum plasma spraying (VPS) was employed to fabricate EBCs systems with 5% MoSi2 (volume fraction, same below)-Yb2SiO5 and 10% MoSi2-Yb2SiO5 as the top layer, Yb2Si2O7 as the intermediate layer, and Si as the bond layer. The corrosion behaviors of these systems under high-temperature water vapor environment at 1350 ℃ were investigated. The results indicate that the MoSi2 doping phase can significantly inhibit the diffusion of oxidants and delay the growth rate of the thermally grown oxide (TGO). After corrosion, the Yb2SiO5-MoSi2 coating transformed into a Yb2SiO5-Yb2Si2O7 composite coating, with good chemical compatibility between the layers. This effectively alleviates thermal stress and inhibits crack propagation.