Sensors and techniques for visualization and characterization of local corrosion

In the study of local corrosion of metals, in which the area attacked is very limited, a method for spatially resolved measurement is required. In this paper, (1) scanning probe techniques such as scanning electrochemical microscopy and micro-capillary electrode, (2) optical imaging and (3) chemical imaging sensor are briefly reviewed. Among those techniques, the chemical imaging sensor is especially advantageous for visualization of pH dynamics in crevice corrosion, because of the features such as label-free measurement and the flat sensor surface. Recent development of the measurement system for in situ observation of pH inside a crevice is introduced.