Carbide formation on carbon steels in CO2 corrosion by use of applied anodic current

Master's thesis in Environmental technologyThe present study aims to validate the method in enriching of iron carbide surface from carbon steels in CO2 corrosion. Applying an anodic current to carbon steel electrodes by galvanostatic measurement was a selected approach. Influence of magnitude of the applied current and exposure time on the corrosion process was studied. The experiments were conducted with CO2-saturated-0.5M NaCl solution as an electrolyte at room temperature and atmospheric pressure. Three different steels, X-65, St52 and Steel33, are used as materials. The corrosion behavior is monitored by weight loss measurement and potentiodynamic sweep, while steel surfaces are examined by SEM/EDS technique. The results show that carbide formation as the weight losses increased with the applied currents and the exposure time. The iron carbide was detected on steel surfaces and iron carbonate was observed on the steel surface which was applied with the highest current density. However, the effect of steel’s microstructure and composition on the corrosion cannot be identified clearly