Electrochemical investigation into the dynamic mechanism of CO2 corrosion product film formation on the carbon steel under the water-condensation condition
By Islam, Md Mayeedul; Pojtanabuntoeng, Thunyaluk; Gubner, Rolf; Kinsella, Brian
Published in Electrochimica Acta
2021
Abstract
In-situ monitoring of CO2 corrosion of carbon steel and FeCO3 precipitation, under continuous replenishing of condensed water conditions, was investigated using a newly developed electrochemical probe. Comparable results were obtained using electrochemical and non-electrochemical methods that validated the design and efficacy of the probe for monitoring corrosion processes such as those that occur in top-of-the-line corrosion. Electrochemical impedance spectroscopy (EIS) combined with cross-sectional analysis identified three stages of corrosion and film formation, namely; active dissolution, formation of a porous film and formation of a more protective film. The protective film consisted of two layers, an inner layer containing a mixture of FeCO3 and Fe3C and an outer layer of FeCO3. During the three stages of corrosion, the corrosion rate increased with time to a maximum value which then declined to minimum values that remained steady with time.