Method for preparing ordered macroporous anodic alumina film by two-step anodic oxidation

Abstract

The invention relates to a method for preparing an ordered macroporous anodic alumina film by two-step anodic oxidation. The method comprises the following steps of: carrying out hard anodizing on aluminum which is subjected to high temperature annealing, ultrasound deoiling and electrochemical polishing treatments in modified oxalic acid electrolyte, so as to obtain a porous anodic alumina film; removing an irregular porous alumina layer which is formed after first anodic oxidation by using a mixed solution of chromic acid and phosphoric acid; then carrying out second anodic oxidation, namely carrying out mild anodic oxidation on the aluminum sheet with the alumina film removed in the modified phosphate electrolyte in a constant voltage manner, wherein the voltage in the second anodic oxidation is completely the same as the voltage in the first anodic oxidation; and finally chambering the test sample subjected to anodic oxidation in a phosphoric acid solution to obtain the ordered macroporous anodic alumina film. The preparation method is carried out under an ice-water bath condition without the requirement on a very low temperature or a high voltage; the cost of used raw materials is low; and equipment is simple and is convenient to operate and easy to control, and therefore the method has a bright application prospect in the modern industry and high and new technology field.

Description

technical field [0001] The invention belongs to the field of preparation of aluminum oxide films, in particular to a method for preparing ordered macroporous anodized aluminum oxide films by a two-step anodic oxidation method. Background technique [0002] For nearly fifty years, Porous Anodic Alumina has been widely studied and applied in various industrial production and scientific research fields. From a structural point of view, the micropore distribution of the porous anodized aluminum layer is highly ordered, showing a hexagonal close-packed periodic structure. The columnar channels are perpendicular to the aluminum substrate and parallel to each other. The pore diameter, pore spacing, and film thickness can be adjusted within a certain range. , the hole density can reach 10 9 ~10 10 / cm 2 , These structural characteristics of porous anodized aluminum and its unique functional characteristics have aroused great interest among scholars, and researchers at home and ab...

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Problems solved by technology

Patent CN101240440A discloses the process of preparing high-hardness and large-aperture thick film by mixed acid anodic oxidation. Phosphoric acid and oxalic acid are used to prepare mixed acid as an anodic oxidation electrolyte. By adjusting the ratio of phosphoric acid and oxalic acid in different electrolytes, the oxidation voltage of 80-150V Anodized alumina with a pore size of 80-140nm was prepared under the following conditions, but the order of the pore size is still not very good

In addition, some researchers also used SiC film, Si 3 N 4 Hexagonal close-packed periodic small pits are printed on the surface of the aluminum sheet. The pitch of the pits depends on the needs. According to different pitches, the corresponding anodizing voltage and electrolyte type and concentration are selected. During anodizing, Holes will grow down along these small pits, and then generate an ordered template with a perfect hexagonal close-packed periodic structure, but this technology is complicated and expensive, and it is difficult to achieve general experimental conditions, let alone large-scale industrialization Production

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