Electrodeposition and characterization of zinc-cobalt alloy from chloride bath;: influence of coumarin as additive

Zinc - cobalt alloys were electrodeposited from chloride bath under continuous current and in the presence and absence of coumarin. The deposit morphology was analyzed using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) was used to determine the preferred crystallographic orientations of the deposits. Zinc-cobalt alloys was without texture in the absence of coumarin whereas, the preferred crystallographic orientations was (103) at 65% in the presence of coumarin. The presence of coumarin yields deposits with a finer grain size. The alloy composition was examined using the Energy Dispersive X-ray Fluorescence Spectroscopy (EDXRF). The percentage of cobalt in the alloy decreases from 1.04 wt.% to 0.69 wt.% in the presence of coumarin. Voltammetric studies show that coumarin affects the reduction of zinc but it was without effect on cobalt reduction. That explains the decrease of cobalt percentage in the alloy in the presence of coumarin. (c) 2007 Elsevier B.V All rights reserved.