Electrodeposition of Sn–Zn and Sn–Zn–Mo layers from citrate solutions

The kinetics of separate reduction and co-reduction of Zn(II), Sn(II) and Mo(VI) from citrate baths were studied. Cyclic voltammetry experiments and galvanostatic deposition in coulostatic conditions were carried out to determine the optimal conditions for electrodeposition of Sn–Zn–Mo layers. The electrodeposits were characterised by chemical analysis (EDS and WDXRF) and profile chemical analysis (GDOES). The optimal conditions for electrodeposition from the citrate baths studied are in the slightly acid range (about pH 5). It was found that the high concentration of sodium molybdate and the addition of sodium sulphite to the electrolyte are essential to electrodeposit zinc–tin alloy with the addition of molybdenum. The results of voltammetric studies and chemical profile analysis indicate some connections between electrodeposition of Zn and Mo.