Research Of Anodizing Technology For Aluminum Plank Used In Fuel Cells

LY12 aluminum alloy by anodizing, as a frame, acts as fixing up and airproofing flow field in Full cells. The study focuses on anodizing technology of LY12 aluminum alloy, and aims to improve corrosion resistance of aluminum alloy in weal acidic full cells' working surrounding at Edges and Corners. Started with studying on the morphology of LY12 aluminum alloy anodic oxide film at edges and corners and combined with chemical immersion test and drop test, the morphology of oxide film is observed at edges and corners, the erode reasons are analyzed by SEM and EPM, then the theoretical analysis is given. Present anodizing technology is improved and innovated. A new anodizing technology of LY12 aluminum alloy suited to full cells is studied. Factors effect on corrosion resistance of LY12 aluminum alloy are studied thoroughly at edges and corners by orthogonal and single factor experiments. The following are conclusions:(1) In this study, the new anodizing technology not only improves corrosion resistance of edges and corners and entire protection function, but also prolongs the life of aluminum alloy parts.(2) SEM and EPM results indicate that cracks form at edges and corners of LY12 aluminum alloy's oxide film. Cracks usually are several microns wide. The width is several decade times than the aperture of sulfuric acidic anodic oxide film. By theoretical analysis, the relationship is defined between Fr value and the formation of the crack of anodic film at the sharp edge. When anodic film cracks, the minimal Rl value is given at the round edge of the Al specimens.(3) Appearance of cracks at edges and corners brings forward a new request for measuring surface corrosion resistance of aluminum alloy anodic oxide film. It is when surface corrosion resistance of aluminum alloy anodic oxide film is measured, the edges and corners should be airproofed to avoid prior corrosion of edges and comers or affecting on testing results of surface oxide film' properties.(4) In anodizing technology which uses sulfuric acid as electrolyte and boiling water sealed, excellent levels, primary and secondary factors effect on corrosion resistance of LY12 aluminum alloy at edges and corners are found out by orthogonal experiments. Effects of factors including electrolysis time, electric current density, electrolyte concentration, the timesealed in boiling water, thickness of oxide film and crack width et al. are studied on corrosion resistance of LY12 aluminum alloy at edges and corners by single factor experiments.