Anodic Polarization Resulting in Passivity

The anodic potentiodynamic polarization curve for zinc in 1 N NaOH is shown in Fig. 5.1(c). In this case, the curve again starts to rise due to diffusion polarization but rather suddenly decreases near -800 mV 

The theoretical predictions or experimental determinations of the composition, thickness, and structure of films responsible for passivity are difficult. The problem of prediction is complicated by many factors, including knowledge of the composition of the solution at the material interface, knowledge of the effects of potentials differing significantly 

Schematic representation of several forms of anodic polarization curves and associated potential decay curves following release of potentiostatic control 

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