Abstract:The development of new generation of high thrust-to-weight ratio aero-engines places severe demands on the service life and temperature of environmental barrier coatings (EBCs). As a material for EBCs, rare-earth silicate applied to the surface layer is prone to longitudinal cracks during service, providing channels for corrosive media to invade and seriously affecting the lifespan of EBCs. MoSi2 has excellent high-temperature properties and is expected to improve the high-temperature stability of rare-earth silicate EBC systems. In this work, MoSi2 was used to modify the Yb2SiO5 top layer, and three types of EBC systems were prepared by vacuum plasma spraying (VPS), with Yb2SiO5-XMoSi2 (X=0, 5 and 10vol.%) as the top layer, Yb2Si2O7 as the intermediate layer, and Si as the bonding layer. The microstructural evolution of the coatings before and after long-term oxidation at 1350 ℃ was studied. The results showed that the MoSi2-doped coating system maintained structural integrity with reduced cracks in the top layer after high-temperature oxidation for 500 h. MoSi2 can consume the oxidizer and slow down the growth rate of TGO inside the coating. The reaction product Yb2Si2O7 was consistent with the composition of the intermediate layer, which had better chemical compatibility and effectively improved the high-temperature performance of the coating system.