In situ microscopic investigation of ion migration on the surface of chromium coated steels

Abstract

Abstract Cathodic spreading of electrolyte on two-layers chromium coatings electrodeposited from trivalent chromium electrolyte on steel was studied on the micro- and the macroscale. The behavior is discussed in view of results obtained on electrical conductivity as measured by current-sensing atomic force microscopy. The coatings were found to hinder electron transport. Heterogeneities observed in the electrical conductivity are correlated to heterogeneities of the electrolyte spreading behavior, studied using in situ scanning Kelvin probe force microscopy. In average, the kinetics of spreading observed at microscopic scales are similar to that observed using a scanning Kelvin probe at larger scales. The scanning Kelvin probe force microscopy is demonstrated as a robust in situ technique to follow electrolyte spreading and study microscopic defects/heterogeneities on the surface.