Study on the sealing of anodic aluminum oxide films prepared by oxalic acid solution

• Main Authors: Chih-hung Tien, 田智宏
• Other Authors: Tsong-jen Yang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/91547347838271757546

碩士 === 逢甲大學 === 材料科學所 === 96 === The porous surface of pretreated and anodized aluminum is full of hydrated alumina. In order to reach the goal of corrosion resistance , pore-sealing process is necessary. Meanwhile, mechanical properties of surface could be improved greatly. Experimental parameters, such as temperature, pH, metal salt content, surfactant amount, and sealing time, were studied for sealing quality in the research work.Electrochemical property and microstructure of porous oxide film were measured by electrochemical methods and scanning electron microscopy. The optimal sealing operating conditions with sealing solution composition are concluded as follows : 80 ℃, pH 5.8, nickel acetate 5 g/l, anionic surfactant 1.95 g/l, non-ionic surfactant 0.39 g/l, sealing time 60 minutes. Two-step sealing process could be useful to improve corrosion resistance of anodized aluminum. Firstly, porous layer is filled with gelatinous metal hydroxides produced by hydrolysis of metal salts. Secondly, swelling of aluminum hydroxide by hydration in boiling water. The double-sealing operation ensures success ful closure of open pores on the surface of porous layer. Better sealing quality leads to better corrosion resistance.