Dual functions of chloride ions on corrosion behavior of mild steel in CO2 saturated aqueous solutions

Corrosion behavior of mild steel in CO2 saturated aqueous solutions at room temperature as a function of concentration of chloride ions was investigated through electrochemical and surface characterizations. In CO2 saturated solutions, mild steel corrodes rapidly with the chloride ions concentration until a peak value around 0.2mol/L as a result of the adsorption and catalytic dissolution mechanism of chloride ions on Fe matrix. In contrast, the corrosion rate of mild steel is retained at a stable value with excess chloride ions, which is ascribed to the limited engagement of CO2 related species in the reaction