Corrosion Behavior and Corrosion Inhibitor for Copper Artifacts in CO₂ Environment

Carbon dioxide (CO₂) is a gaseous pollutant found in museums that can seriously damage the original appearance of copper artifacts through local acidification and corrosion. Aiming to simu-late the CO₂ induced corrosion of the real copper artifacts, a quartz-crystal microbalance (QCM) in con-junction with corrosion products analysis techniques is used to reveal the initial corrosion behavior and regularities of Cu in the CO₂ containing environment. Furthermore, vapor-phase corrosion inhibitors (VCI) compounded with benzotriazole (BTA) and L-cysteine (CYS) were specifically formulated to improve the anti-corrosion ability of Cu. In this work, we investigated the anticorrosive mechanism of VCI on Cu by means of electrochemical impedance spectroscopy (EIS) technology and density functional theory (DFT). The results demonstrated that with the increase of CO₂ concentration and relative humidity content of the environment, the Cu corrosion was accelerated, and the initial corrosion products consist mainly of Cu₂ O, CuO and CuCO₃ ∙Cu(OH)₂ after exposure to CO₂ environment. BTA and CYS have significant synergistic anti-corrosion performance for Cu. When the compound radio of BTA to CYS is 4∶1, the highest corrosion inhibition efficiency is 86.2%. Which may be ascribed to that the CYS molecular with relatively smaller size can fully fill the defects of the BTA film, thus causing a greater densification of the anti-corrosion film.