Exploring the influence of flue gas impurities on the electrochemical corrosion mechanism of X80 steel in a supercritical CO2-saturated aqueous environment

The influence of flue gas (100 ppmv of O2, NO2 or SO2 in CO2 steam) on the corrosion mechanism of X80 steel in a supercritical CO2-saturated aqueous (water-rich phase) environment at 8.0 MPa and 35 ℃ was explored via electrochemical methods combined with off-line analyses. While O2 mainly promoted the anodic reaction process, NO2 and SO2 primarily enhanced the cathodic reaction process. Compared with SO2, NO2 and O2 dramatically reduced the protection offered by X80 steel’s corrosion product layer in the water-rich phase. In addition, the study also found that O2 significantly promoted the localized corrosion of X80 steel in the water-rich phase.