Microstructure and initial corrosion response of electrodeposited/cold sprayed copper coating interface regions on used nuclear fuel containers

A current design of used nuclear fuel containers incorporates a copper corrosion barrier coating fabricated through a combination of electrodeposition and cold spraying technologies. This study investigates the early-stage corrosion behavior of this copper coating under aerobic conditions in 3 M NaCl solution, with particular emphasis on the electrodeposited/cold sprayed copper interface, which exhibits the highest microstructural heterogeneity with distinct corrosion morphologies. Electrodeposited copper demonstrates texture-dependent corrosion, with an increase in the area fraction of more corrosion resistant {001}-oriented grains following annealing at 350°C or 600°C for one hour. In contrast, in cold sprayed copper, corrosion is more pronounced at splat-splat interfaces due to presence of copper oxide inclusions, though annealing enhances the uniformity of corrosion as a result of oxide coarsening. Additionally, a recrystallized layer at the electrodeposited/cold sprayed copper interface was identified with increased random grain orientations leading to a less localized corrosion behaviour.