Voltage Oscillations during Anodic Polarization of Zinc in Water Solutions of NaOH

Abstract

The present brief research deals with the appearance of voltage oscillations during galvanostatic anodization of Zn in the NaOH electrolyte. Hence, this research aims to describe the observed voltage oscillations, giving the most probable explication for their occurrence. Following previous results, the anodization was performed at 30 or 50 mA•cm-2 in diluted 0.002 M NaOH aqueous solution for 100 or 240 s at room temperature. The respective voltage alterations were recorded and submitted for further analysis. The obtained curves and the probable reasons for the observed voltage oscillations were analyzed in detail. The main research result has become a concept for the correlation between the oscillations and the alteration of the growing layer resistivity. This suggests that the resistivity alters due to local heating effects inside the film. These effects probably cause irreversible structural changes in the bulk of the growing film, obviously related to the occurrence of oxygen vacations. In this sense, this study initiates an entirely new field of investigation regarding the phenomena related to the Zn anodization in alkaline media at high current densities.