Microscopic aspects of electrochemical delamination: an SKPFM study

Abstract

While the basic mechanisms of anodic and cathodic delamination, i.e. the de-adhesion of polymer coatings from the metal substrate, are already well understood [Industrial Adhesion Problems, Orbital Press, Oxford (1985); Polymeric Materials for Corrosion Control, American Chemical Society, Washington (1986); Corrosion Control by Organic Coatings, NACE, Houston, TX; MRS Bull. 24 (1999) 43; Corros. Sci. 43 (2001) 207; Corros. Sci. 43 (2001) 229; Corros. Sci. 43 (2001) 243; Corros. Sci. 41 (1999) 547; Corros. Sci. 41 (1999) 579; Corros. Sci. 41 (1999) 599], only little is known about the microscopic and submicroscopic aspects of delamination. The main difficulty for a detailed investigation of delamination with a suitably high resolution is that the de-adhesion is a process occurring at a buried interface. On the macroscopic scale Scanning Kelvin Probe Microscopy (resolution of about a few 10 μm) has been the most important method to elucidate the fundamental processes of cathodic and anodic delamination, which in combination with other methods such as photoelectron spectroscopy (XPS) and measurement of the adhesion strength in dependence on distance from the defect helped to develop detailed models [MRS Bull. 24 (1999) 43; Corros. Sci. 43 (2001) 207; Corros. Sci. 43 (2001) 229; Corros. Sci. 43 (2001) 243; Corros. Sci. 41 (1999) 547; Corros. Sci. 41 (1999) 579; Corros. Sci. 41 (1999) 599]. The development of the scanning Kelvin probe force microscopy (SKPFM) opened application of the Kelvin probe technique to the submicroscopic scale. In this paper, first results of these submicroscopic investigations are presented and discussed in view of the earlier results.