A study on the corrosion behavior of 7072/3004/7072 clad aluminum alloy in different media

Abstract

Cladding is an easy and economical method to design multifunctional aluminum structures with improved corrosion resistance, mechanical strength, and physical appearance. In this study, the electrochemical properties and corrosion behavior of an aluminum-clad product made of 7072/3004/7072 aluminum alloys were investigated by Tafel extrapolation and impedance spectroscopy. 3004 aluminum sheet was used as core, and it was cladded with 7072 aluminum sheets on both sides. The long-term corrosion behavior of clad samples was examined after being immersed in tap water, rainwater, and 3.5 wt.% NaCl solution for 4 weeks. The results show that because of the potential difference between 7072 and 3004 aluminum alloys, 7072 alloy behaves more anodic and corrodes preferentially (with a slower rate) compared to 3004 aluminum alloy. Cladding 3004 with embossed 7072 alloy improves the corrosion resistance of the alloy. Moreover, the electrolyte comparison demonstrates that the carbonate-forming ions (such as Ca) in tap water and HCO3-, NO3-, and SO(4)(2-)in rainwater decelerate the corrosion rate.