Localized electrochemical study on the interface corrosion between organic coating/metal substrate

Localized electrochemical techniques such as scanning Kelvin probe (SKP), localized electrochemical impedance (LEIS) and scanning electrochemical microscopy (SECM) have been applied to many fields due to their high accuracy and high space resolution in local area. This paper briefly introduces the measuring principle of localized electrochemical techniques and their key problems, such as the measurement of corrosion potential with SKP, the selection of redox mediator for SECM and the determination of scanning frequency for LEIS. The emphasis is put on the application of above mentioned three techniques to the study of corrosion behavior at the interface between organic coating and metal substrate. In light of it, the unique advantages of three techniques are elucidated, including on interface morphology acquiring, the deduction and verification of corrosion mechanisms for the interface corrosion and their affecting factors. Meanwhile, the representation of parameters, like interface potential, interface resistance/capacitance and interface current that involved in characterizing processes, is discussed. It is proved that in respect of the interface corrosion, localized electrochemical study complements general electrochemistry well, which is fundamental to the establishment of local electrochemistry for the interface corrosion between organic coating and metal substrate. Also, it has to be recognized that in order to enlarge the applicability of these techniques, they must be further improved in the aspect of ultromicroelectrode size and used jointly with other advanced techniques.