Surface Analysis of Anodized Aluminum Panels that have been Painted, BeadBlasted, Cleaned, and Treated with a Chemical Conversion Coating, Tri-Service Committee on Corrosion Proceedings

摘要

Aluminum panels were prepared to simulate the process an aircraft undergoes forrepainting. This process consisted of stripping the original paint down to the anodized aluminum by bead blasting with polymethyl methacrylate (PMMA), cleaning the surface, corrosion removal, followed by a chemical conversion coating. The chemical conversion coating was applied on panels from 0 to 15 minutes. The surface analysis was performed using a Surface Science Instrument Model 501 ESCA. The surface analysis has shown several interesting phenomena that occurred on the panels. The phenomena includes non uniformity of the surfaces, changes in the atomic concentrations, and changes in the organic layers. Changes in the chemical states of the elements vs. the chemical conversion coating times were also detected. The non uniformities were present in both the elemental surveys and the high resolution scans. The elemental surveys showed that the atomic percent of the elements (especially Cr) changed with the chemical conversion coating time. The high resolution scan of carbon showed that a layer of PMMA was left on the surface after bead blasting. After cleaning and applying the chemical conversion coating compound, the organic layer consisted of mainly hydrocarbons and alcohols/ethers, however, areas with slight amounts of PMMA were also detected. The high resolution scans of the aluminum peaks showed that the chemical states of aluminum changed with the chemical conversion coating time. The surface aluminum changed from an unoxidized aluminum to a mixture of an oxide and a possible complex oxyfluoride surface at longer coating times.