Comparative investigations on the electrochemical behaviors among Al and aluminum alloys

Abstract

Al and aluminum alloys are widely used in the transportation industry and aerospace field owing to their low density. They are always utilized as the sheathing materials, whose corrosion resistances need special attention. In the study, the electrochemical impedance spectroscopy (EIS) measurements and potentiodynamic polarization tests are performed on pure Al, aluminum alloys 2A97, 6061, 7050 and 2024. The corrosion behaviors of the five materials are respectively characterized by the resultant indicators, such as the corrosion potential E _c , the corrosion current density I _c , the corroded surface morphology and the frequency characteristics. The materials sequences that determined respectively by these indicators are compared with each other. The conflicts among these sequences are found. Then potentiostatic polarization measurements are carried out on the five materials. The instantaneous characteristic of the corrosion potential and polarization current density of each material during its corrosion process is revealed. Because of the characteristic, it is concluded that the potentiostatic polarization measurement and resultant polarization current density are more suitable to characterize the corrosion behaviors of Al and aluminum alloys. The investigation could provide help in the exploitation of new aluminum alloys with the better corrosion property.

Keywords

• electrochemical behavior
• aluminum alloy
• potentiostatic polarization measurement
• polarization current density