High temperature water vapor corrosion behavior of Y2O3 mixed Si bonding layer of environmental barrier coating under 1400 °C

In this paper, a Y2O3 modified Si composite bond layer in Yb2Si2O7 coating was prepared by atmospheric plasma spraying (APS) to encapsulate SiC ceramic matrix composites. The high-temperature oxidation behavior of two types coatings in an environment of 1400 degrees C and 35 % VOL steam-air was systematically studied. The results show that the Si bonding layer generates SiO2 during oxidation. With the increase of oxidation time, the vertical cracks in the Yb2Si2O7 layer continuously extend, providing channels for steam diffuses inward, ultimately leading to the coating failure due to the consumption of Si. However, the doping of Y2O3 into the Si bonding layer results in the formation of a stable and dense Y2Si2O7 protective layer as Y2O3 reacts with SiO2 under high temperatures. The binding energy of Si atoms for both Y2Si2O7 and Yb2Si2O7 was calculated, and it was found that the former (-13.92 eV) is much greater than the latter (-6.79 eV). The Y2Si2O7 layer formed from the reaction can effectively enhance the high-temperature steam oxidation resistance of EBCs.