Voltammetric studies on the role of additives in bright zinc electrodeposition from an alkaline non-cyanide bath

Abstract

Influence of various carrier additives and brightener additives on the voltammetric behavior of zinc electro deposition from an alkaline non-cyanide bath was studied. Two different cathodic peaks were observed. Peak I has been attributed to hydrogen reduction/UPD of zinc and peak II to reduction of the metal. The extent of polarization of the zinc deposition to more negative potentials and the corresponding peak current decide the nature of deposits. PVA was found to be the best carrier additive. PVA chains retain zinc hydroxyl anions and control the speed of the rate determining step. Unsaturated aldehydes bring about 3-dimensional nucleation and further increase the polarization when added with PVA.