Effects of the metal-ceramic continuous transition region on the tensile strength and crack propagation behavior of 8YSZ/CoNiCrAlY coating

In this study, micro-8YSZ/CoNiCrAlY continuous transition coatings and double-layer coatings were prepared by atmospheric plasma spraying (APS) technology. The microhardness of the continuous transition coating changed in a manner consistent with the microstructure, and the average bond strength of the continuous transition coating was 1.40 times higher than that of the double-layer coating, and conducted an in-depth study of the role of the continuous transition zone in the coating stretching process. During the stretching process, not only the ceramic coating breaks, but also the continuous transition zone breaks. In the continuous transition zone, cracks undergo deflection and bridging during initiation and propagation. In addition, the existence of approximately saddle-shaped CoNiCrAlY metal splat was also found. The approximately saddle-shaped metal splat absorbs and dissipates energy by deforming during the stretching process. In summary, the interlocking structure, crack deflection and bridging mechanisms in the continuous transition zone, and the deformation of the approximately saddle-shaped metal splat synergistically improve the bonding strength of the coating.