Correlation between predictive and descriptive models to characterize the passive film

By C. Boissy and B. Ter-Ovanessian and N. Mary and B. Normand
Published in Electrochimica Acta NULL 2015

Abstract

Passive metals play a key role in many fields. The numerous phenomena affecting the behavior of the film are linked to the main issue that help us to understand the processes of passivation. The description of Electrochemical Impedance Spectroscopy (EIS) data allows us to evaluate kinetic parameters, but there are many models offered and it is difficult to select one to fit \EIS\ data. Mass transport is a significant factor when characterizing the passive film and it is a good way of identifying models. This study proposes a methodology allowing us to choose the most appropriate model and to determine objectively if the mass transport has to be taken into account. The mass transport coefficient of the point defect through oxide is determined through the Point Defect Model. Knowing the thickness of the oxide, through X-ray Photoelectron Spectroscopy (XPS) analysis, the time constant of the transport is determined. Based on this value, a descriptive model is selected avoiding the over-parameterization of the \EIS\ data. This methodology is used in acidic solutions at 30

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