Inquiry On The Sealing Methods Of Hard Anodic Oxidation Film On 3003 Aluminum Alloy And Its Properties

3003 aluminum alloy is Al-Mn alloy, which has good corrosion resistance, heat conductivity and excellent processing performance. It is widely used in architectural decoration, household kitchen utensils and appliances, refrigeration devices, electronics, aerospace and so on, and is one of the most widely used antirust aluminum. Hard anodic oxidation of aluminum is a method which means forming a dense aluminum oxide film with high hardness and thickness on the surface of aluminum. However, due to the numerous pores in the porous layer, the aluminum oxide film is easily attacked by the corrosive chemicals from environment. Therefore, in order to improve its corrosion resistance, hole sealing process must be conducted. At present, the sealing technology of the anodic aluminum oxide (AAO) film increasingly tends to be efficient and environmental.In the thesis,3003 aluminum alloy was anodized in sulphuric acid electrolyte under constant current density. Then, a thin organic, inorganic or inorganic-organic layer with excellent alkali resistance was fabricated on AAO film surface by adopting composite sealing process. The surface morphologies before and after alkali corrosion of the films prepared by different sealing methods were studied using scanning electron microscope. And the strong alkali corrosion resistances of the films were also investigated. The results show that the corrosion resistance of AAO film can be improved by sealing using stearic acid aqueous solution. The optimum composition of sealing solution and process parameters are as follows:stearic acid SA:1.0～2.0gL-1; additive A:12.5～17gL-1; additive B:1.5～2.0gL-1; sealing temperature:95～100℃; sealing time:30 min; pH=7.5-8.5.An inorganic-organic layer on H2SO4-HAAO (hard anodic aluminum oxide) film were fabricated using two kinds of salt sealing and stearic acid sealing. The composite film’s surface morphology characteristics before and after corrosion test, corrosion resistant performance and mechanism were studied. The alkali resistances of AAO films obtained from different sealing methods were compared based on the results of strong alkali resistance tests. The results show that the best method is 6# sealing method (silicate-stearic acid composite sealing) which can significantly improve the the alkali corrosion resistance of AAO film, and the bubbling time can be up to 22 min long. The optimum composition of sealing solution and process parameters are as follows:stearic acid SA:1.0～2.0gL-1; additive A:12.5～17gL-1; additive B:1.5～2.0 g L-1; silicate C solution:20 vol%; additive D:3～5gL-1; sealing temperature:95～100 ℃; sealing time:30 min; pH=7.5～8.5.3003 aluminum alloy was anodized in the mixed acid electrolyte:organic acid A: 60 g L-1, organic acid B:40 g L-1 and inorganic acid C:3～5 mL L-1 under constant current density. Different sealing methods were used to form different protective layers on the HAAO surface. Scanning electron microscope and corrosion test were adopted to study the combination performance between the composite film and the HAAO film and the corrosion resistance of the protective layer as a whole. The research results show that the alkali resistance of mixed acid HAAO film is better than that of ordinary sulfuric acid HAAO film. Stearic acid SA+additive A+additive B and stearic acid SA +additive A+additive B+silicate solution C+ additive D mixed sealing systems can provide good sealing effects and the bubbling time can be up to 22 min long, which can significantly improve the alkali resistance performance of the mixed acid HAAO film.