Electrochemical behaviour of aluminum alloys in natural seawater

In natural seawater, pure aluminum develops oxide layer which forms a barrier, protecting against corrosion. Alloying with other elements prevents the development of oxide layer by introducing localized galvanic cells. Different aluminum alloys exhibit different electrochemical behavior. The scope of the project was to study the electrochemical behavior of different chemical composition of aluminum alloys in natural seawater. The significance of understanding the corrosion behavior of aluminum alloys is essential in the fabrication of sacrificial anodes to be used in cathodic protection in corrosion control. Aluminum alloys were fabricated using alloying elements Zn, Sn, Mg, Cu, Fe, and Si. Divided into two groups, samples of aluminum alloys in Group 1 contain same weight percent of Zn, and different weight percent of Sn. Aluminum alloy samples in Group 2 contains same weight percent of Mg, Cu, Fe and Si with different weight percent of Sn. The samples were then subjected to corrosion behavior experimentation which includes Tafel plot, corrosion potential and potentiodynamic scan. It was found that alloying with Mg, Cu, Fe, and Si instead of alloying only with Zn and Sn further increases the negative potential, the density of particle distribution and further reduces the corrosion rate of aluminum alloys. The activeness of aluminum alloys also increases when alloyed with Zn, Sn, Mg, Cu, Fe, and Si.