Synthesis, microstructure and corrosion behavior of compositionally graded Ni-YSZ diffusion barrier coatings on inconel-690 for applications in high temperature environments

Cubic YSZ coating and compositionally graded Ni-YSZ nanocomposite coating have been developed on Inconel-690 using electron beam physical vapor deposition technique to act as a chemical diffusion barrier. The microstructure and chemical composition of the graded coating have been characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, electron probe microanalysis, X-ray photoelectron spectroscopy and secondary ion mass spectroscopy techniques. Electrochemical corrosion study was carried out in 3 M HNO3 medium and it was found that compositionally graded Ni-YSZ coating heat treated at 1273 K in air showed superior corrosion resistance than as-deposited compositionally graded Ni-YSZ and YSZ coatings on Inconel-690 substrate.