Investigation of Cerium Salt/Sulfuric Acid Anodizing Technology for 1420 Aluminum Alloy

The effect of cerium addition on the property of an anodized coating on 1420 Al alloy was studied by corrosion experiment (immersion test and neutral salt spray test), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and measurement of polarization curves. The result show that only pitting could be observed in all corrosion tests while intergranular corrosion and exfoliation corrosion did not appear on 1420 Al-Li alloys. When organic carboxylic acid S or the cerium (IV) salt was added into sulfuric acid anodizing electrolyte separately, there was no significant improvement in corrosion resistance of the anodized film. However, in the case of adding them into the sulfuric acid anodizing electrolyte together, the corrosion resistance of the anodized film increased greatly owing to a synergistic effect. The synergistic effect may relate to the formation of a cerium-organic carboxylic acid S complex compound and its effects on film growth and film structure. (Author)