Electrochemical dielectric response of steel corrosion induced by chloride in simulated concrete pore solution

Abstract

Electrochemical and dielectric properties of steel oxide films can have an impact on the corrosion process but are still poorly understood due to the unavailability of measurement methods. In this study, electrochemical impedance spectroscopy (EIS) was adopted to interpret steel corrosion induced by chloride in a simulated concrete pore solution. Particularly, validation of EIS data by Kramers–Kronig transforms was performed prior to further EIS interpretation. Relative dielectric permittivity of corroded steel/electrolyte interface was derived through theoretical induction and corrosion products were analyzed by X-ray photoelectron spectroscopy. Results indicated that measured EIS data in the present study depicted good causality and stability. Corrosion at the steel/electrolyte interface induced by increasing chloride led to high relative permittivity within the low frequency domain while marginal difference could be observed at the high frequency range. AC conductivity of corrosion products at steel/solution interfaces revealed a notable frequency dependence, based on which three distinct frequency regions were subdivided.