Study Of Preparation And Characterizaton On AAO Film With Support

In this dissertation, the preparation of anodic aluminum oxide(AAO) membrane with a support, the characterization of membrane's pore structure, the flexibility and permeability have been studied. The morphology and structure of the pores of AAO membrane were determined by means of Scanning Electron Microscopy (SEM) and X-ray Diffraction(XRD). The flexibility and corrosion resistance are studied by electrochemical methods and heat treatment. the flexibility of porous alumina membrane is analyzed by Electrochemical Impedance Spectroscopy (EIS) , The pores size, distribution, porosity are characterized by bubble point test and boiling method.The membrane of AAO prepared by electrochemical anodic oxidation process is a water-included membrane with poor flexibility. After heat treatment, the flexibility and corrosion resistance have been obviously changed. The effects of time and temperature of heat treatment and the electrolyte component have been investigated. The results show that the primary factor which effected flexibility of AAO is the electrolyte component. About the AAO membrane in phosphoric acid, the higher temperature of the heating process, the better flexibility. The flexibility of oxide membrane will not change when it arrived at a certain temperature, and it will be destroyed when been over-heated. The flexibility of oxide film is related to the time of heating. For AAO membrane in sulfur acid and oxalic acid, the flexibility of membrane has been destroyed obviously, there are many defects of the film after heated treatment. The polarization curve of films indicates that the corrosion resistance of AAO membrane is improved after been heated in phosphoric acid.At room pressure, the EIS of AAO membrane in H₂O/H₂O, 0.1MNaCl/H₂O, 0.1MNaCl/0.1MNaCl solutions shows that practical systematic circuit of porous alumina film can be expressed with (RC)R(QR)R(RC). The EIS analysis of AAO membrane in phosphoric acid show the plots of Nyquist are a Warburg impedance spectroscopy obviously in NaCl/H₂O system. It has the characterization of pervasion. In Bode spectroscopy, the magnitude of impedance is decreased gradually with the increasing of permeability time; the change of the impedance with the frequency has the similar process for the film in the above three solutions, the impedance value is decreased gradually with the time increasing, and the value is comparatively lower in the high frequency area. During this period, the qualitative analysis of permeability of AAO membrane is feasible in phosphoric acid by means of EIS. The EIS is not characterized the permeability in sulfur acid and oxalic acid solutions.The characterization of the AAO membrane is an important index for evaluating the quality and application field of the film. The pore structure, pore size distributing frequency, average pore diameter and maximal pore size can be determined by means of bubble point test. The porosity of alumina membrane is measured by boiling method and SEM, and the reason for the difference of the two methods is discussed.