ABSTRACT
The corrosion behaviour of uncoated metals and alloys as well as those modified with surface coatings is commonly evaluated by global electrochemical techniques, viz., potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), etc. Such measurements provide the electrochemical response of the entire electrode surface at a macroscopic level in the form of an averaged voltage and current. Among the various localized electrochemical methods, scanning electrochemical microscopy (SECM), localized electrochemical impedance spectroscopy (LEIS), scanning vibrating electrode technique (SVET) and scanning ion-selective electrode technique (SIET) have received considerable attention. This chapter addresses the principles, key requirements, modes of operation, limitations and utility of these techniques in corrosion research. Being a non-invasive method, SVET possesses the unique ability to clearly distinguish the cathodic and anodic areas, the reactions occurring on them locally and to measure the change in magnitude of current with time. Although this development was aimed at characterizing biological samples, Isaacs has extended its application for corrosion research.
