Nano cobalt coating corrosion behavior obtained by DC and PC electrodeposition process

In this study direct (DC) and Pulse (PC) current electroplating technique was used for coating of nano Co onto copper. The coating applied by cathodic pulse electrodeposition and the variation of electrochemical parameters such as current density and pulse conditions caused a marked change in the microstructure of the deposit. Characterization of coated was investigated by XRD, and SEM techniques. The deposited nanocrystalline Co on the Cu substrate in the experimental conditions achieved ultra fine crystalline structure is about 65nm. The corrosion behavior of coarse grain (CG) and nanocrystalline Co was studied by using potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in 3.5%wt sodium Chloride (NaCl) solution. Results showed that in the NaCl solution, the Nanocrystalline Co exhibited improved corrosion resistance when compared with coarse grained Co coatings, which is due to the higher grain boundary density in nanocrystalline materials to quickly form a stable and protective passive film.