Incentives for using local electrochemical impedance methods in the investigation of organic coatings

Abstract

The assessment of changes in organic coatings in a corrosive environment has traditionally utilized global electrochemical methods, such as electrochemical impedance spectroscopy (EIS), in which a relatively large area of the sample is examined. Recently, more localized methods of impedance measurement have been developed and used to map heterogeneities across a sample surface, and the temporal changes of these regions. These localized methods are essential to further understand the breakdown process of coated alloys that inevitably occurs at discrete sites. This paper will examine the incentives for making local electrochemical impedance measurements, the advantages and limitations of this method, some of the lessons learned, and the present understanding of local breakdown processes on model-coated substrates.