In situ SECM study on concentration profiles of electroactive species from corrosion of stainless steel

The corrosion behaviours of type 304 stainless steel in acidic chloride solutions were investigated by cyclic voltammetric (CV) measurements at a scanning electrochemical microscope (SECM) tip combined with SECM scan imaging techniques. The results showed that the detection of electroactive species (i.e. ferrous ions) originating from the corrosion process can be accomplished as a function of position of the SECM tip above the stainless steel sample. Moreover, the variation in the tip–sample distance would allow for the tip current to be quantitatively correlated with the concentration profiles of the electroactive species or the related electrochemical activities on the sample surface. In a word, both voltammetric characteristic and three-dimensional SECM imaging related to the corrosion behaviours of 304 stainless steel will be helpful to clarify the possible pathways and reaction mechanisms involved in the corrosion processes.