Visualização da corrosão do aço 1020 ao longo do tempo utilizando SVET

The Vibrating Scanning Electrode Technique (SVET) uses a probe to check the potential variation in a solution due to ionic fluxes arising from electrochemical reactions occurring in a metal during the corrosion process. Among different applications of the Scanning Electrochemical Microscope, is the study of the corrosion processof metals, for example, aluminum, steel, iron and copper alloys, which can be bare or coated with coatings Organisms, provided that the cathodic and anodic regions can be detected. With the objective of studying the slow corrosion of carbon-steel 1020 (1cmx1cm), the results were obtained using a standard NaCl solution whose conductivity was corrected to be close to that of tap water (100 μS cm-1at 25 ° C). The spatial evolution of the sample corrosion processes as a function of time (30 and 120 minutesof immersion) was observed. After analysis by SVET, the sample was evaluated using an optical stereoscope(OE). The image shows that there is corrosion, but it does not identify the redox process of the moment, which can only be confirmed by the SVET maps. Therefore, the SVET technique, because it is classified as a semi-quantitative measure, is more advantageous in relation to the optical images, since the response obtained indicates the activity at the time of acquisition of the map data. In addition, the anodic zones with more positive potentials susceptible to corrosion (red) of the cathodic zones, with more negative and reducible potentials (blue), are differentiated. Thus, it is concluded that the SVET technique is effective to determine precursor sites for degradation processes in a 1020 carbon steel plate, using a solution with conductivity very close to the water conductivity of Curitiba-PR.