Strong anodic oxidation method for preparing porous pellumina

Abstract

The invention relates to an intensive anodic oxidation process to prepare porous anodic alumina film. An aluminum sheet is as an anode; a platinum sheet as a cathode; argon as shielded gas; mixed solution of perchloric acid with absolute alcohol as electrochemical polishing compound for the aluminum sheet; mixed solution of oxalic acid, absolute alcohol and deionized water as electrolyte; and mixed solution of phosphoric acid, chromic acid and deionized water as alumina film corrodent. Through aluminum sheet annealing, purging, electrochemical polishing, mild anodic oxidation, corrosion on aluminum sheet oxide film, intensive anodic oxidation and stripping oxide film, and finally, pale yellow, high purity and ordered porous-structured nanometer-leveled alumina film is achieved; The alumina film pore is in circular shape sized in 30 to 35nm, pore distance in 80 to100nm and pore depth in 162.4 micrometers; growth rate of the alumina film is 54 micrometers / h, which is 27 times higher than 2 micrometers / h of growth rate of anodic oxidation aluminum film prepared through mild anodic oxidation process.

Description

Technical field: [0001] The invention relates to a strong anodic oxidation method for preparing porous aluminum oxide film, which belongs to the field of film forming technology on the surface of non-ferrous metal materials. Background technique: [0002] Aluminum is a relatively active metal, which can naturally form an oxide film with a thickness of several hundred nanometers in the air. This oxide film is amorphous, thin and porous, and has low mechanical strength, which cannot meet the requirements of functional applications. To obtain an oxide film layer with special functions, the aluminum surface must be treated. In the electrolyte, aluminum is used as an anode for electrolytic treatment to form an oxide film on the aluminum surface, which is called aluminum anodic oxidation. The anodic aluminum oxide film is divided into barrier type and There are two types of porous type. Usually, a dense barrier oxide film can be obtained by anodizing in a neutral electrolyte, whil...

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Problems solved by technology

[0005] Using sulfuric acid, oxalic acid, or phosphoric acid as the electrolyte, the anodizing method performed near the optimum value of the oxidation voltage is called mild anodization, or MA method for short. The disadvantage is that the porous aluminum oxide film is prepared, and the film thickness increases. The rate is only 2μm / h. So far, due to the slow growth rate of the aluminum oxide film thickness, the secondary anodizing method based on the MA method has not been applied in industry, and there are still many defects and deficiencies.

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