Progress And Challenges in Supercritical CO2 Corrosion and Protection: A Review

Internal corrosion during dense-phase CO2 and SC–CO2 transport and injection is jointly governed by interfacial aqueous phases, impurity reactions, and the evolution of the corrosion product films. This review systematically examines phase behavior, water content, impurities, temperature and pressure, flow, exposure time, materials, welded joints, stress, mineral ions, protection strategies, and prediction models. Sustained electrochemical corrosion requires the formation of free water, condensation, or a connected thin water film. O2, SO2, NO2, and H2S control damage morphology by modifying aqueous chemistry, cathodic processes, hydrogen entry, and the stability of FeCO3 and FeS-containing corrosion product films. The nonmonotonic effects of temperature, pressure, and flow velocity mainly arise from differences in the wetting state, interphase partitioning, and corrosion product film evolution. Mean corrosion rates derived from mass loss are insufficient to characterize pitting and stress corrosion cracking risks. On the basis of electrolyte formation, interfacial reactions, corrosion product film stability, and damage morphology, this Review proposes an assessment framework for material selection, corrosion prediction, and integrity management.