Microstructure and corrosion resistance of pulse electrodeposited Ni–Cr coatings

Abstract

In this study, Ni–Cr alloy coatings were obtained on mild carbon steel surface by direct current (DC) and pulse current (PC) electrodeposition from a kind of acid solution. X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscope (AFM) were used to analyse the phase structure and surface morphology. The microhardness of the Ni–Cr alloy coatings was evaluated using microhardness tester. The electrochemical behaviour of the Ni–Cr alloy coatings was investigated by polarisation curves and electrochemical impedance spectroscopy (EIS) in 3·5 wt-% NaCl solution. The results indicated that the microstructure and corrosion resistance of the Ni–Cr alloy coatings were greatly affected by electrodeposition method. The PC alloy coatings exhibited more compact surface, higher microhardness and better corrosion resistance compared with those of the DC alloy coatings.