Electrodeposition of zinc plus iron alloys II. Relation between the stripping results and ex-situ characterization

Zn + Fe alloy electrodeposition under potentiostatic conditions was studied in chloride medium on vitreous carbon from solutions with relatively low m etal concentrations. It has been demonstrated that electrochemical strippin g techniques can be used to characterize the Zn + Fe alloy deposition proce ss. Morphological and compositional studies, along with structural XRD anal ysis, enabled the electrodeposition conditions for obtaining a defined coat ing with defined characteristics to be specified. Anomalous codeposition of Zn + Fe alloy was maintained under gentle stirring conditions until zinc-r ich deposits were obtained. In highly zinc-rich deposits, in which only the eta-phase is present, a distorted platelet-like shape was seen. The zinc o xidation of these deposits took place in only one peak; plateau region in t he electrochemical stripping curves. A slight increase in iron in the depos its (%Fe > 4%) caused significant changes in both morphology and structure. For these deposits a second, more negative, peak plateau region was record ed for the zinc oxidation in the stripping curves. Although the eta-phase r emains the phase mainly formed, the greater difficulty; of zinc oxidation i s interpreted as a consequence of the interactions between the eta-phase an d a new phase that probably has an fee structure. (C) 1999 Elsevier Science S.A. All rights reserved.