| 摘要 |
PROBLEM TO BE SOLVED: To obtain alumina film having extremely fine pores and to enable the selective separation of a mixture of gas and liq. which has been difficult heretofore, at the time of producing porous aluminum oxide film by subjecting aluminum to electrolysis, by intermittently applying electrolytic voltage thereto. SOLUTION: Al having 99.5 to 99.99% purity is immersed in an electrolyte of sulfuric acid or the like, and, with Al as the anode and the electrode of platinum or the like in the electrolyte as the cathode, intermittent voltage having a rectangular sawtooth or sine wave shape is applied thereto to produce porous alumina film. As for the form of a porous alumina anodically oxidized film producing device, the platinum cathode is set to an A tank on the side of a soln., e.g. composed of sulfuric acid and water and producing the film between two soln. tanks of A and B holding an Al sheet as the raw material. The anodic oxidation treatment is executed in such a manner that the concn. of the electrolyte is regulated to about 0.1 to 2mol/L, and the intermittent voltage of 1 to 50V (with 10 to 10kHz frequency) is applied for 0.1 to 40hr to form the alumina coating on the Al sheet being in contact with the electrolyte in the A tank.
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