Corrosion Behavior of Electrodeposited Nickel Coatings on AZ91 Mg Alloy

In this study، nickel was electrodeposited onto the surface of AZ91 Mg alloy and its corrosion resistance was compared with those of AZ91 Mg alloy and pure nickel using polarization and electrochemical impedance spectroscopy (EIS) experiments in a 3. 5 wt. % NaCl solution. The structure of coating was investigated by means of X-ray diffraction، and the specimen’s morphology and the coating’s chemical composition were analyzed using scanning electron microscope (SEM). The results showed that the coating has a nano-crystalline structure with the average grain size of 95 nm. The results of corrosion tests showed a decrease in the corrosion current density from 2. 5×10-4 A. cm-2 for the uncoated sample to 1. 5×10-5 A. cm-2 for the coated specimen، as well as an increase in the corrosion potential.