Characterisation of localised corrosion processes using scanning electrochemical impedance microscopy

• The concept of scanning electrochemical impedance microscopy
• Distinguishing domains of similar topography but different corrosion properties
• Characterisation with higher informative power during corrosion tests

The concept of scanning electrochemical impedance microscopy (SEIM) is described for the studies of localised corrosion processes at metallic surfaces under conditions which simulate those present in the environment. SEIM is based on acquisition and comprehensive analysis (with modelling and spectra fitting) of arrays of localised impedance spectra obtained in a single area scan. This gives accurate quantitative information about important corrosion properties of non-uniform metal surfaces. It is demonstrated that SEIM-approach is advantageous in visualisation of surface domains with similar topography and morphology but different electrochemical properties as well as enables extracting parameters important in assessing local corrosion currents.