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Aluminum Plate Anodizing Process

Aug 30, 2017

1, anodized aluminum oxide oxide film production of the general principle: aluminum as the anode placed in the electrolyte solution, the use of electrolysis, so that the surface of the process of forming alumina film, known as the anodic oxidation of aluminum. The cathode in the device is a high chemical stability in the electrolytic solution of materials, such as lead, stainless steel, aluminum and so on. The principle of aluminum anodic oxidation is essentially the principle of water electrolysis. When the current passes, the hydrogen is released on the cathode; on the anode, the precipitated oxygen is not only the molecular oxygen, but also the atomic oxygen (O) and the ionic oxygen, usually expressed as molecular oxygen in the reaction. Aluminum as an anode is oxidized by the oxygen precipitated to form an anhydrous alumina film, and the resulting oxygen does not act entirely with aluminum, and some of it is precipitated in a gaseous form. The same time as

2, anodized aluminum oxide oxidation solution choice: anodic oxide film growth is a prerequisite for the electrolyte should be dissolved on the oxide film. But this does not mean that in all the dissolved electrolyte in the anodic oxidation can produce oxide film or the formation of the same oxide film properties. The same time as

3, anodized aluminum oxide plate oxidation type: anodic oxidation in the form of current is divided into: DC anodizing, AC anodizing, pulse current anodizing. According to the electrolyte are: sulfuric acid, oxalic acid, chromic acid, mixed acid and sulfonic acid as the main solution of natural coloring anodic oxidation. According to the film sub-points are: ordinary film, hard film (thick film), porcelain membrane, bright decorative layer, the role of the semiconductor barrier layer of anodic oxidation. Aluminum and aluminum alloy commonly used anodic oxidation methods and process conditions see Table -5. Among them, the application of DC sulfuric acid anodic oxidation method is the most common. The same time as

4, anodic oxide plate oxide film structure, nature: anodic oxide film consists of two layers, porous thick outer layer is in the dielectric properties of the dense inner layer on the growth, the latter known as the barrier layer (also Called active layer). Electron microscopy observation, the film of the vertical and horizontal surface almost all appear with the metal surface perpendicular to the tubular hole, they penetrate the outer membrane until the oxide film and metal interface barrier. To the pores around the main axis is dense alumina constitute a honeycomb hexagonal body, called the unit cell, the entire film is composed of many such cells. The barrier layer is composed of anhydrous aluminum oxide, thin and dense, with high hardness and to prevent the current through the role. The barrier layer is about 0.03-0.05 μm, 0.5% -2.0% after the total membrane. The outer layer of the oxide film is mainly composed of amorphous alumina and a small amount of hydrated alumina, and also contains the cation of the electrolyte. When the electrolyte is sulfuric acid, the sulfate content in the film is 13% -17% under normal conditions. Most of the excellent properties of the oxide film are determined by the thickness and porosity of the porous outer layer, which are closely related to the anodic oxidation conditions