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

AbstractTo prolong the service life and structural stability of CoCrNiAlY–yttria stabilized zirconia–LaMgAl11O19 (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/cm2 at 20 h to 10.63 mg/cm2 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 Y2O3 induced the formation of a dense α‐Al2O3 reaction layer on the top LaMA layer, which greatly prevented the internal penetration of O2. 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/cm2 at 20 h to 8.73 mg/cm2 at 80 h. Potential oxidation damage mechanisms of the coatings with or without AlY plating layer were comprehensively clarified.