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Author
Lin, C. | Nguyen, T. | McKnight, M. E.
Title
Relation Between AC Impedance Data and Degradation of Coated Steel. 1. Effects of Surface Roughness and Contamination on the Corrosion Behavior of Epoxy-Coated Steel.
Coporate
National Institute of Standards and Technology, Gaithersburg, MD
Journal
Progress in Organic Coatings, Vol. 20, 169-186, 1992
Keywords
steels | degradation | contamination | corrosion | surface roughness | coatings
Abstract
The effects of surface roughness and inorganic chloride contamination on the corrosion behavior of steel coated with thin, amine-cured epoxy films have been investigated using AC impedance spectroscopy. The results were analyzed using the equivalent circuit models to identify the different steps in the corrosion of coated steel. Two types of corrosion were observed depending on the surface treatment: point-attack corrosion for uncontaminated and bilstered corrosion for contaminated surfaces. Both types of corrosion can be discerned by AC impedance spectroscopy and modeled by the equivalent circuits. Coating-deficient areas at the peaks of sandblasted substrate have been calculated accurately from the AC impedance data and verified by scanning electron microscopy.