Zinc passivation and the effect of mass transfer in flowing electrolyte

Abstract

Passivation times,t p, of a zinc sheet anode have been found to vary from 2 min to 2 h over the experimental range of electrolyte velocities (0.075 to 0.20 ms−1), current densities (3,160 to 1,675 A m−2) and electrolyte temperature (298 to 333 K). Fort p longer than about 40 min there was a change in the nature of the experimental dependence oft p on the electrolyte flow rate and the current density. A satisfactory theoretical model of the dissolving zinc anode involving the diffusion of the soluble species through a growing porous solid layer on the electrode surface and through the electrolyte diffusion layer has been formulated to explain the dependence oft p on the experimental variables.