1209.3404 (Bosco Emmanuel)

Passivity of Metals: Potential-Step Transients for Passive Current
Density and Barrier Layer Thickness in the Point Defect Model    [PDF]

Bosco Emmanuel

In an earlier pre-print we developed a variant of the point defect model that corrected a flaw in one of the defect reactions and to be specific reaction 3 of the original point defect model was replaced by reaction 3prime of the variant. Here we apply the corrected model to find the time evolution of the passive current density and the barrier layer thickness. Though the functional forms agree with the forms reported earlier by Macdonald and co-workers, the composition of the parameters differ significantly. This explains the experimental success of the flawed model. This semblance is also manifested in the diagnostics for the current transient involving the time-derivative of the current density. The present theory will be useful for the correct analysis of transients which result from switching the potential in the anodic or cathodic direction from an initial steady state.

View original: http://arxiv.org/abs/1209.3404