Electrodeposition of Cu-Zn alloy from a Lewis acidic ZnCl ₂-EMIC molten salt

The electrodeposition of copper and copper-zinc alloys was investigated on tungsten and nickel electrodes in a Lewis acidic 50.0-50.0 mol % zinc chloride-1-ethyl-3-methylimidazolium chloride molten salt containing copper(I). The composition of the electrodeposited Cu-Zn alloys can be varied by deposition potential, temperature, and Cu(I) concentration of the plating bath. Analysis of the chronoamperometric transient behavior during electrodeposition suggests that pure copper electrodeposition proceeds via three-dimensional instantaneous nucleation with diffusion-controlled growth. However, as the deposition potential crosses from Cu metal into the alloy-forming range, the nucleation process changes to three-dimensional progressive nucleation with diffusion-controlled growth. Analysis of the X-ray diffraction patterns indicates that the electrodeposited Cu-Zn alloys exhibit α and β phases. The surface morphologies and the compositions of the electrodeposited Cu-Zn alloys were studied with scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS).