Improved EIS Analysis of the Electrochemical Behaviour of Carbon Steel in Alkaline Solution

International audienceSteady-state polarization curves, X-ray photoelectron spectroscopy, and impedance spectroscopy were used to explore the electrochemical properties for carbon steel in alkaline electrolytes. The complex-capacitance representation allowed determination of a capacitance value at high frequency, from which the oxide film thickness could be estimated. These results are in good agreement with values obtained using the power-law model, providing a single mathematical model that is shown to apply in both the anodic and cathodic domains for the characterization of an oxide layer

Imaging of a Thin Oxide Film Formation from the Combination of Surface Reflectivity and Electrochemical Methods.

International audienceElectrochemical methods (cyclic voltammetry (CV), potential steps, and electrochemical impedance spectroscopy) were successfully combined with in situ reflectometry measurements for a detailed analysis of the passive layer evolution as a function of the electrode potential. Interestingly, both EIS and surface reflectivity allowed a film thickness in the nanometer range to be readily determined. In addition, transient analyses of the reflectivity simultaneously recorded with CVs show the formation of both Fe2O3 and Fe3O4 oxides. The image analysis showed that the steel surface reactivity is heterogeneous and presents micrometric islands coated with a thicker oxide layer than the surrounding surface. The in situ combination of these techniques thus offers a powerful analytical description of the interface on a local scale and its transient response to a perturbation