Electrochemical behaviour of Cr coating in acidic sulphate solution studied by cyclic polarization and impedance spectroscopyстатья
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Дата последнего поиска статьи во внешних источниках: 12 октября 2013 г.
Аннотация:Corrosion resistance of Cr coatings was studied in a weak acidic sulphate solution using cyclic voltammetry and impedance spectroscopy. The results of the cyclic polarization measurements indicated that initially stable state of Cr coating was conditioned by presence of the air oxide film filling all the defects in the coating. During anodic scan, dissolution of this film and penetration of the aggressive solution to the substrate occur and this causes corrosion of the substrate. Measurements of electrochemical impedance were carried out at the open circuit potential after immersion in the studied solution for different time periods (from 30 S to 24 h), The results were analyzed according to the equivalent circuits that are usually used for a description of corrosion processes. The data show that only a small portion of the initial thickness of Cr coating may be dissolved during the Corrosion process. It has been shown that impedance data are useful to estimate in situ inhomogeneity of these coatings and their protection ability, quantitatively.