Long term durability against water vapor corrosion at 1500 °C for environmental barrier coating modified by alumina

Abstract

Advanced aero-engine have made environmental barrier coatings work in an increasingly harsh service atmosphere. In this work, the water-vapor corrosion behaviors up to 200 h at 1500 °C of Yb₂Si₂O₇-Al₂O₃ coatings prepared using core-shell structured powders were explored. Results showed that the Al₂O₃ shell hindered the deposition of Yb₂SiO₅ secondary phase in the sprayed coating due to the low vapor partial pressure of substances containing Al. During corrosion, the in-situ consumption of Al₂O₃ in the coating actualized the premature decrease of Yb₂SiO₅, and generated the aluminosilicate, ultimately reducing the maximus tensile stress by about 32 %. Moreover, the external diffusion of Al, activated the formation of protective Yb₃Al₅O₁₂ reaction layer, instead of porous Yb₂SiO₅ layer on Yb₂Si₂O₇-Al₂O₃ coating, achieving a lower mass loss than the pristine Yb₂Si₂O₇ coating, indicating an improved durability of Yb₂Si₂O₇-Al₂O₃ coating.