Transient Passivation Kinetics of Reactive Metal Electrodes. I. Theory

摘要

A chemical model is presented that describes the voltage delay often observed when an anodizing current is applied to a highly reactive metal electrode. The model considers the metal surface to be initially covered by a protective film that is disrupted by the passage of anodic current. Relaxation of the surface coverage causes a rise in electrode potential during the initial stages of anodization. The faradaic impedance represented by this model is calculated, and the dependence of the impedance on the rate constants and coverage parameters is examined. For this model, it is shown that voltage delay should exist only when the rate of surface-coverage relaxation is less than the rate of the principal charge transfer process. (Author)