Enhanced structural stability of yttria‐stabilized zirconia–LaMgAl11O19 dual ceramic coating by an α‐Al2O3 layer

Abstract To prolong the service life and structural stability of CoCrNiAlY–yttria stabilized zirconia–LaMgAl 11 O 19 (LaMA) dual ceramic coating during high temperature exposure, an AlY plating layer was deposited on top LaMA. Results revealed that this coating without AlY plating layer showed a rapid mass increase from 6.62 mg/cm 2 at 20 h to 10.63 mg/cm 2 at 80 h, but also suffered from a fast TGO growth and severe elemental diffusion, resulting in an exacerbating interface fracture of the coating. However, AlY plating layer was first oxidized, and Y 2 O 3 induced the formation of a dense α‐Al 2 O 3 reaction layer on the top LaMA layer, which greatly prevented the internal penetration of O 2 . This coating with AlY plating layer showed a relatively stable structure, a very slow TGO growth, and a slight mass increase trend from 8.19 mg/cm 2 at 20 h to 8.73 mg/cm 2 at 80 h. Potential oxidation damage mechanisms of the coatings with or without AlY plating layer were comprehensively clarified.