Influence of Current Density onto Composition and Corrosion of Electrodeposited Ni-Zn Alloys

The initial corrosion rates of electrodeposited Zn-Ni coating under galvanostatic conditions are closely related to the current density. The NH4Cl 12-14 wt% Ni coating showed better corrosion resistance than the other investigated coatings due to the lower Ni content of 9 wt%. Moreover, nodular granules closely packed with capillary fissures, along with the formation of the electrochemically noble gamma-Ni5Zn21 phase, were observed at the highest Ni concentration of 10 wt%. The results of electrochemical characterization on the copper substrate showed an extended testing time, indicating a nobler corrosion potential. Additionally, the grain size refines with the presence of NH4Cl, and the increase in cathodic current density can also lead to a decrease in grain size.