Study of the influence of the polyalcohol mannitol on zinc electrodeposition from an alkaline bath

In this paper, the effects of adding mannitol to an alkaline plating bath on the electrodeposition of zinc onto AISI 1010 steel are described and assessed. From cyclic voltammograms with various lower-limit potentials, it is concluded that an initial zinc bulk deposition (region of wave c (0)) occurs from -1.45 V in the negative sweep. When the sweep is reversed at -1.60 V, an anodic peak a (1) is seen in the positive sweep both in the absence and in presence of mannitol, which was assigned to zinc dissolution. This peak indicates that the primary nucleation and growth of zinc in region c (0) is followed by zinc secondary nucleation and growth (region of peak c (1)). Scanning electron micrographs show that zinc electrodeposits obtained at mannitol concentrations a parts per thousand yen0.10 M were more refined than at lower concentrations. Energy-dispersive X-ray spectroscopy of these electrodeposits show oxygen contents that are generally low or below detection limit.