Microstructure and corrosion properties of La₂Zr₂O₇/NiCoAlY thermal barrier coatings deposited on inconel 718 superalloy by laser cladding

In order to improve the seawater corrosion resistance of Inconel 718 superalloy, a La₂Zr₂O₇/ NiCoCrAlY thermal barrier coating corrosion resistant to 3.5 wt.% NaCl aqueous solution was prepared by laser cladding on Inconel 718 superalloy. X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and electrochemical techniques were used to study the microstructure and the corrosion performance of the coating in 3.5 wt.% NaCl solution. The results show that the thermal barrier coating is mainly composed of primary La₂Zr₂O₇ phase and γ + laves/δ phase eutectic structure. The corrosion potential and corrosion current of the coating in 3.5 wt.% NaCl solution are higher and lower than that of the Inconel 718 substrate, respectively, indicating that the corrosion performance of the coating is better than that of the Inconel 718 substrate. The presence of La₂Zr₂O₇ phase in the thermal barrier coating is the main reason for its corrosion resistance to 3.5 wt.% NaCl solution.