Electrochemical characterization of Cu film fabricated via wire arc additive manufacturing in oxic groundwater

Abstract

Abstract We investigated the electrochemical corrosion behavior of Cu films fabricated using wire arc additive manufacturing (WAAM) as a candidate canister material for deep geological disposal (DGD). The investigation was conducted in an oxic groundwater solution. The initial corrosion potential and corrosion current density of the WAAM-Cu film obtained from potentiodynamic measurements were similar to those of conventionally fabricated Cu (forged Cu) in oxic groundwater, regardless of the addition of chloride ions. To investigate the long-term corrosion behavior, WAAM-Cu was immersed in a chloride-added oxic groundwater environment for 120 d, and open-circuit potential and electrochemical impedance spectroscopy measurements were performed at specific time intervals. The total polarization resistance of the WAAM-Cu was lower than that of the forged Cu; this was possibly due to the difference in the structural properties of the copper oxide layer formed on the surface. Surface analysis revealed that general corrosion occurred on the WAAM-Cu; however, the surface roughness was higher than that of forged Cu. Moreover, delamination of the corroded layer of the WAAM-Cu was observed. To ensure corrosion resistance and long-term stability in the context of DGD repository conditions, further research is necessary to optimize the WAAM technique for the fabrication of Cu films.