Cold Drawn Steel Surface Analysis in Contact with Saline Solution: Analysis Using Electrochemical Atomic Force Microscopy

High strength steels in concrete structures used as reinforcement are usually passivated due to the physical barrier that concrete provides and by a protective passive film developed on the surface by the high alkaline media. Chloride ions can break the passive film. These ions can be found dissolved in the water or in structures in marine environment. This work is focused on the study, by Electrochemical Atomic Force Microscopy (EC-AFM), of the early stages of corrosion of such steels during exposure to a sodium chloride solution in order to better understand the evolution of the dissolution of steel phases. Additionally, it is estimated the corrosion rate by topographical images and simultaneously by means of measuring the corrosion rate through the linear polarization technique performed in an electrochemical cell specially developed in the AFM microscope. The results show the evolution of the topographical profiles which are compared during some period of time with the electrochemical results