The effects of substrate material on the microstructure of pulse-plated Zn-Ni alloys

The effect of substrate material on the microstructure (surface morphology, phases present and preferred :orientation) and chemical composition of Zn-Ni alloy electrodeposits, produced from a chloride-based electrolyte using the square-wave pulse-plating technique, has been investigated. Steel and commercial-purity, cold-rolled copper substrates were considered. The results indicated that changing from a steel to copper substrate does not have a significant influence on the deposit characteristics, except for the variations in the chemical composition. These variations were attributed to a number of factors including; (1) the different initial electrode potential (open circuit potential); (2) differences in cell voltages due to different electrical resistivity of the two metals; and (3) possibly to surface energy considerations. Because of the similar microstructure obtained, these coatings should have similar properties. (C) 1997 Elsevier Science S.A.