Novel Interpretation of Volta Potential Measurements from In-Situ SKPFM for Localised Corrosion Analysis in Aluminium Alloys

Volta potential measurements from Scanning Kelvin Probe Force Microscopy (SKPFM) have been used over the years to discuss the nobility of an alloy’s surface and its tendency to localised corrosion. This has led to classical interpretations that may (unfortunately) over-generalise the actual Volta potential behaviour of the surface during ongoing localised corrosion. Consequently, issues on correlating Volta potential measurements to corrosion potentials and mechanisms arise. With the advent of in-situ SKPFM, which allows for the Volta potential measurements during ongoing dynamic surface electrochemical and/or physicochemical reactions, novel observations regarding Volta potential evolution are available. This calls for an updated and re-evaluated interpretation of the Volta potential measurements from SKPFM relating to localised corrosion analysis. The novel interpretation includes an additional layer of information, as compared to classical interpretations; there is greater information on the role of interfacial parameters and time (kinetics). Optimistically, this will bridge the gap of Volta potential measurements and its correlation to corrosion potentials.