An Electrochemical Model for Prediction of Corrosion of Mild Steel in Aqueous Carbon Dioxide Solutions

TLDR: In this paper, a predictive model was developed for uniform carbon dioxide (CO2) corrosion, based on modeling of individual electrochemical reactions in a water-CO2 system, taking into account the reactions of hydrogen ion (H+) reduction, carbonic acid (H2CO3) reduction, direct water reduction, oxygen reduction, and anodic dissolution of iron.

Abstract: A predictive model was developed for uniform carbon dioxide (CO2) corrosion, based on modeling of individual electrochemical reactions in a water-CO2 system. The model takes into account the electrochemical reactions of hydrogen ion (H+) reduction, carbonic acid (H2CO3) reduction, direct water reduction, oxygen reduction, and anodic dissolution of iron. The required electrochemical parameters (e.g., exchange current densities and Tafel slopes) for different reactions were determined from experiments conducted in glass cells. The corrosion process was monitored using polarization resistance, potentiodynamic sweep, electrochemical impedance, and weight-loss measurements. The model was calibrated for two mild steels over a range of parameters: temperature (t) = 20°C to 80°C, pH = 3 to 6, partial pressure of CO2 (PCO2) = 0 bar to 1 bar (0 kPa to 100 kPa), and ω = 0 rpm to 5,000 rpm (vp = 0 m/s to 2.5 m/s). The model was applicable for uniform corrosion with no protective films present. Performance of...