Interface corrosion behavior of copper-aluminum laminated composite plates in neutral salt fog

Abstract

The corrosion behavior of pure copper, aluminum, and Cu–Al laminated composite plates produced through semi-molten continuous casting and rolling exposed to salt fog were evaluated. The copper performed the best corrosion resistance, then the aluminum. At first a corrosion belt occurred along the interface next to the diffusion layer (intermetallic) at the preliminary stage on the aluminum side, the generated cracking corrosion products formed an another galvanic cell with surrounding aluminum matrix, where the aluminum as the anode, and then pits appeared on the aluminum near the interface and gradually expanded to larger and deeper holes, while some small holes appeared on the other areas of aluminum as the process went on, and then corrosion products exerted stress on the surface of grain to come up denudation. Finally, localized corrosion gradually developed to general corrosion. Besides, with the extension of corrosion time, the corrosion rate of Cu–Al firstly decreases, then increases and finally decreases again.