Characterization and corrosion behavior of Ni-Cr coatings by using pulse current electrodeposition

Purpose The purpose of this paper is to study the effect of chromium content on the microstructure and corrosion resistance of Ni-Cr coating. Design/methodology/approach Ni-Cr coating was prepared by pulse current electrodeposition with trivalent chromium. On the basis of studying effect of electroplating parameters on composition and morphology, Ni-Cr alloy coatings with various chromium contents were obtained. The microstructure was characterized by scanning electron microscopy, X-ray diffractometer and transmission electron microscopy. Corrosion behavior was studied by potentiodynamic polarization and electrochemical impedance spectroscopy techniques. Findings Electrodeposited chromium was solidly dissolved in nickel and refined the grain of the coating. With the increase of Cr content, the corrosion resistance of Ni-Cr coating was enhanced, which is due to the formation of continuous nickel hydroxide and compact chromium oxide passive films. Originality/value Ni-Cr alloy coating without penetration crack was prepared in trivalent chromium electrolyte, and the mechanism of its excellent corrosion resistance was proposed.