Electrodeposition of Sn-Mn Layers from Aqueous Citrate Electrolytes

Abstract

The conditions for manganese with tin electrodeposition from aqueous citrate electrolytes were studied. Partial polarization curves were determined. The influence of applied potential, electrolyte composition and pH level, hydrodynamic conditions and quantity of charge passed, on the electrodeposition of Sn-Mn layers were determined. The surface composition of deposits was ascertained by chemical analysis (WDXRF). The morphology of coatings was studied by SEM. The phase composition of Sn-Mn samples was determined by X-ray diffractometry and Raman spectroscopy. The electrolysis parameters allowing electrodeposition of Sn-Mn coatings containing various amounts of Mn (in the range from about 0.5 wt% to 42 wt%) were selected. The morphology of deposits depends significantly on the content of manganese and on the parameters of electrolysis. The surface morphology of samples with Mn content of about 27 wt% is not uniform, two types of areas with significant differences in chemical composition are observed. XRD studies indicate that four crystallographic phases are formed in the deposits (β-Sn), MnO, Mn(OH)2, and MnSn2, while Raman spectroscopy revealed also the presence of α-MnO2, MnOOH, and SnO2, which are the products of chemical processes taking place simultaneously with electrolysis. The mechanism of the co-deposition of manganese with tin has been proposed.