Galvanic Corrosion Behavior between Aluminum and Copper Caused by NaCl Aqueous Solutions

Abstract

In this work, polarization measurement, galvanic current density measurement and spray test were carried out on aluminum (Al), copper (Cu) and Al/Cu couples in NaCl aqueous solutions with different temperatures and different levels of NaCl and aeration. The corrosion current density of Al at 323 K in aerated 1.0 mass% NaCl solution is about 60 times as high as that deaerated with nitrogen, whereas the corrosion current density in aerated 1.0% NaCl solution at 323 K is about 3 times as high as that at 303 K. The corrosion potentials of Al and Cu shifted to negative direction when the NaCl concentration increased from 0.01% to 1.0%. A clear passive region was observed on the Al specimen when the NaCl concentration is below 0.005%. The galvanic current density between the Al/Cu couple increased with the increase in NaCl concentration. In the spray test, the corrosion on the Al side of the Al/Cu couple became more severe with the increase in NaCl concentration and the decrease in the face-to-face distance between Al and Cu.