Measurement of local galvanic surface corrosion using scanning electrochemical microscopy on ductile cast iron

The application of scanning electrochemical microscopy has increased recently in corrosion studies. The electrochemical activity image is usually generated indirectly by measuring the rate of reaction of a mediator which is not a part of the studied system. This work aims at developing an experimental technique to use scanning electrochemical microscopy without using electrochemically active species. Galvanic corrosion of ductile cast iron was studied by pulsing both the sample and tip electrode to cathodic and anodic regions. By tuning the pulse parameters, the current response of the tip differs in the vicinity of iron and graphite, leading to the imaging of the oxidation/reduction processes.