| The naturally high corrosion resistance of aluminum is sacrificed when aluminum is alloyed with other elements that improve its strength and suitability for industrial applications. The Al 2024 alloy, which is widely used in the aerospace industry, is particularly susceptible to localized corrosion due to the presence of intermetallic phases of high copper content. Currently chromates are the most widely used and effective inhibitors for the corrosion of these alloys. However, due to the toxicity of Cr(VI), the Environmental Protection Agency (EPA) is calling for a replacement of chromates used in commercial coatings.; The contribution of this lab has been to study the reactions that occur in an aggressive environment and how chromate and other inhibitors inhibit these reactions. By understanding how chromate works, it should become easier to identify a safe replacement for chromate in conversion coatings. Various techniques have been employed to study local changes in the composition and morphology of the aluminum surface. Scanning electron microscopy (SEM) along with Energy Dispersive X-ray analysis (EDX) was used for observing the changes in the surface morphology and composition, respectively, after various treatments. Auger electron spectroscopy (AES) has been used to obtain elemental compositional analysis at the surface of the oxide film, as well as the film thickness and elemental composition through the depth, determined by Auger Depth Profiling (AES-DP).; Because it is known that the adsorption of ions on a metal affects the corrosion resistance of that metal, ion adsorption on aluminum is an important issue. In this study, the adsorption/accumulation of proposed inhibiting ions on aluminum has been studied using a radioactive labeling method. Chromate and phosphate adsorption data enhances the information gained from localized dissolution studies. The effectiveness of pertechnetate as a corrosion inhibitor for aluminum alloys has been investigated through radiometric adsorption studies. The effects of solution pH, electrode potential, and ion content in the supporting electrolyte have been studied and their effect on the accumulation of technetium on aluminum is reported. |
