The Study Of Preparation And Influencing Factors Of Anodic Alumina Membrane

The alumina by anodizing technique can be not only used for material decoration and protection, but also used for filtering membrane because of its uniform, parallel pore size and high pore porosity and other characters. In this paper, the details of the whole process of preparing anodic alumina membrane were studied; the membranes were detached from Al substrate by chemical resolution and voltage consequence technique. The microstructure of membrane in different reaction conditions was observed by SEM, TEM, X-ray diffraction. The effect on structure and flow rate were discussed , the optimum reacting condition was obtained. The results show that the anodic alumina membranes were in amorphous state in different reacting condition. Annealing will improve the pore structure. Anodizing voltage was the main influencing factor of pore size, thickness, porosity. The types of electrolyte had effect on the membrane characters. The pore size and flow rate were small and current efficiency were high for membranes in sulfuric acid, whereas the former values were large and the latter were low for membranes formed in phosphoric acid. The values of membranes formed in oxalic acid were in between the above values. The thickness increased and then decreased as the temperature increased. The main reason was that the high temperature facilitated the dissolution of the membranes. Moreover, the barrier layer membranes were obtained with high current efficiency, vice visa. Soaking time had effect on flow rate of membrane detached by voltage consequence technique. The ratios of the thickness of membrane to the thickness of Al consumed were between 1.39 and 1.41 in best pore structure formed in different electrolytes.