Evaluating the Corrosion Behaviour of Copper during Deliquescent Drying/Wetting Cycles in Humid Air

Abstract

This study aimed to investigate the effects of different salts on the corrosion of copper under conditions anticipated in a deep geological repository (DGR) during the initial unsaturated period. The study was conducted using NaCl, CaCl₂ , and MgCl₂ , which are known to be the salts most likely to be found on the surface of used fuel containers in a DGR. Additionally, the study utilized salts from CR-10E, a simulated groundwater that closely approximates the groundwater conditions in a crystalline rock formation in the Canadian Shield. Long-term vapour-phase corrosion experiments were conducted on cold-sprayed copper coupons with these different salts loaded onto them, and a suite of surface analysis techniques was used to analyze the corrosion products. Quartz crystal microbalance (QCM) experiments were also performed on copper coated with NaCl, and the corrosion process was monitored in real-time. Further wet-dry cycling was performed with the QCM, and revealed that the corrosion products formed on the Cu after 20 days were deliquescent.