Electrodeposition of Zn-V oxide composites from a strongly agitated solution without dispersed particles

The electrodeposition of a Zn-V oxide composite under galvanostatic conditions from an agitated sulfate solution without dispersed particles and containing Zn²⁺and VO²⁺at pH 2 and 313 K was investigated. Although the V content in the deposits initially decreased with increasing current density, irrespective of the flow rate of electrolyte, a further increase in the current density resulted in an increase in the V content of the deposits. The curves, which show the relationship between the V content in the deposits and the current density, shifted to the higher-current-density region with increasing flow rate of the electrolyte. Agitation of the electrolyte decreased the V content of the deposits but reduced the segregation of V oxide. EDX point analysis of the cross-section of the deposits revealed that the V oxide concentrated at the surface of the deposits. The polarization curves in 3% NaCl solution revealed that the corrosion potential of the deposited Zn-V oxide films depended on the V content in the deposits, irrespective of the flow rate of electrolyte, and that the corrosion potential shifted toward the more noble direction with the codeposition of V oxide when the V content in the deposits was less than 2 mass%. At V contents of <4 mass%, the corrosion current density of the deposits decreased with increasing V content. The corrosion current densities of the deposits obtained from agitated solutions were smaller than those of the deposits obtained from unagitated solutions.