National Synchrotron Light Source Seminar

Aluminum corrosion is an important industrial concern. Studies have indicated the aluminum corrodes more quickly in sea water, and when in contact with copper, either metallic or as Cu(II) in solution. Since Cu is a more noble metal than Al, a Galvanic cell can be established easily, promoting aluminum oxidation. The ‘chloride acceleration effect’ is well established, and is the major reason for accelerated aluminum corrosion in sea water. Aluminum natively forms a tough, impervious oxide (Al2O3) layer on its surface upon natural exposure to air. This impedes the redox reaction until it is removed. Acidic (< pH 4) and basic (> pH 9) conditions will dissolve the oxide layer and accelerate aluminum corrosion as well. Several groups have investigated the kinetics of the Cu/Al displacement reaction with and without added chloride, termed a copper cementation reaction. , , I have determined that the kinetics model developed for a rotating aluminum disk in reaction with a copper(II) solution works well for the much simpler reaction of household aluminum foil with copper(II) solution. In addition, my research has revealed that bromide also accelerates the corrosion of aluminum. The ‘halide acceleration effect’ was found to be quite significant, speeding up the reaction by about 100x and shortening the induction period. What the halide ion does to actually speed up the reaction is still unclear. I plan to continue my investigations to determine the dependence of the acceleration effect on the relative concentration of chloride as well as investigate the relative effect of fluoride on aluminum corrosion.