New developments in scanning microelectrochemical techniques: a highly sensitive route to evaluate degradation reactions and protection methods with chemical selectivity

Abstract

The scanning electrochemical microscope (SECM) offers a highly sensitive route to evaluate degradation reactions and protection methods with chemical selectivity by using ion-selective microelectrodes as tips, thus operating SECM potentiometrically. Spatially resolved imaging of electrochemical reactivity related to each component of the investigated material can thus be effectively monitored selectively both in situ and in real time. The applicability of this method has been illustrated using two practical examples of galvanic corrosion processes, namely a model Zn-Cu pair, and a metal-coating system consisting in the exposure of cut edges of coil-coated galvanized steel to aqueous saline environment. In this contribution, localized pH and zinc(II) ion distributions originated around the corroding systems immersed in 1 mM NaCl solution are shown