Effect of NiCrCoAlY Transition Layer Thickness on Structure and Properties of BNT/NiCrCoAlY Ceramic Coatings

In order to avoid the deterioration of electrical properties of Bi_0.5Na_0.5TiO₃ (BNT) ceramic coatings and metal substrate due to poor bonding performance, a NiCrCoAlY layer was introduced as a transition layer between BNT ceramic coatings and metal substrate. In this paper, BNT/NiCrCoAlY ceramic coatings were prepared by supersonic plasma spraying. The effects of NiCrCoAlY transition layer thickness on microstructure, mechanical properties, electrical properties, and domain evolution of BNT/NiCrCoAlY ceramic coatings were analyzed. The thickness of the NiCrCoAlY transition layer has a significant effect on the mechanical properties of BNT/NiCrCoAlY ceramic coatings. When the thickness of the NiCrCoAlY transition layer is 159.1 μm, the residual compressive stress on the surface of the NiCrCoAlY transition layer is the largest, which is − 185.4 MPa, and the direct bonding performance between the coating and substrate is the best. The residual compressive stress of the coating has a good positive effect on the hardness and bond strength of the coating, which significantly improves the structural integrity and mechanical properties of the coating. BNT2 ceramic coating has the largest average amplitude intensity of 46.0 pm, and the amplitude histogram ranges from − 10 to 90 pm. BNT2 ceramic coating has a relatively large value of the maximum amplitude of the butterfly loops at ± 20 V, and its localized piezoelectric response (PR_max) reaches 449.6 pm/V, and the ferroelectric domains exhibit an obvious switching behavior.