The influence of substituted aromatic aldehydes on the electrodeposition of Zn-Mn alloy

Additives are necessary in the electrodeposition of Zn-Mn alloys at high current densities, in order to reduce the hydrogen evolution reaction and prevent dendrite formation. The influences of two aromatic aldehydes, 4-hydroxy-benzaldehyde and 3,4-dimethoxy-benzaldehyde, as additives in the Zn-Mn plating electrolyte, were examined in this study. The characterization of the coatings by scanning electron microscopy and X-ray energy dispersive spectroscopy, as well as an examination of the effect of the additives by electrochemical methods, indicated a complex involvement of additive molecules in hydrogen evolution, as well as in Zn2+ and Mn2+ reduction. Consequently, a levelling action could be achieved and the chemical composition of the Zn-Mn alloy tailored by the addition of the proper type and concentration of additive in the plating electrolyte.