Passivity Breakdown of Copper in Borate Buffer Solutions Containing Cl−, SO42−, and NO3−

Abstract

The effects of Cl−, , and on the corrosion of copper in slightly alkaline, deaerated borate buffer solutions (BBS) were analyzed by potentiodynamic polarization, in situ surface-enhanced Raman spectroscopy, electrochemical impedance spectroscopy, scanning electron microscopy, and confocal microscope. Results showed that all three ions significantly affected the corrosion of copper in BBS, leading to a decrease in the breakdown potential for copper, thereby promoting passivity breakdown. The adsorption of Cl−, , and on the copper oxide film surface was detected, forming corrosion products, atacamite, brochantite, and gerhardtite, respectively. The passivity breakdown occurred at a lower potential for -containing solutions than for those with the other ions. The most severe corrosion morphology was obtained in -containing solutions, and large-scale pits with deep depths were distributed on the copper surface after passivity breakdown. In comparison, small pits and laterally growing pits and/or local rupture of the passive film occurred on the copper surface in the solution containing Cl− or after passivity breakdown.