Electrodeposition of zinc-iron alloy from an alkaline bath in the presence of sorbitol

The chronopotentiometric technique was used to analyze the electrodeposition of Fe-Zn film on a Pt electrode. Three different Fe3+/Zn2+ molar ratios, Fe26.8 wt.%-Zn73.2 wt.%, Fe46 wt.%-Zn54 wt.% and Fe66.6 wt.%-Zn33.4 wt.%, were used in a solution containing sorbitol as the Fe3+-complexing agent, with a total concentration of the two cations of 0.20 M. Coloration of Fe-Zn films were light gray, dull dark gray and bright graphite, depending on the Fe3+/Zn2+ ratios in the deposition bath. The highest stripping to deposition charge density ratio was 47.5%, at 15 mA cm(-2) in the Fe26.8 wt.%-Zn73.2 wt.% bath. Energy dispersive spectroscopy indicated that the codeposition type of Fe and Zn in the Fe26.8 wt.%-Zn73.2 wt.% and Fe46 wt.%-Zn54 wt.% baths was normal at all j(d) tested, while in the Fe66.6 wt.%-Zn33.4 wt.% bath there was a transitional current density from normal to equilibrium codeposition at 50 mA cm(-2). Scanning electron microscopy showed that Fe-Zn films of high quality were obtained from the Fe66.6 wt.%-Zn33.4 wt.% and Fe26.8 wt.%-Zn73.2 wt.% baths, since the films were smooth. X-ray analysis of the Zn-Fe films obtained at 15, 25 and 50 mA cm(-2), in the Fe26.8 wt.%-Zn73.2 wt.%, Fe46 wt.%-Zn54 wt.% and Fe66.6 wt.%-Zn33.4 wt.% plating baths, suggested the occurrence, in general, of a mixture of Fe11Zn40, Fe4Zn9, ss Fe, alpha Fe, Fe2O3, Zn and PtZn alloys in the deposit.