Small aluminium alloy anode oxidation equipment:
1) the structure of anodic oxide film consists of two layers, the outer layer is called porous layer, thicker, porous and low resistance. The inner layer is called barrier layer (also called active layer). It is thinner, denser and high resistance. The porous outer layer is grown on a dense inner layer with dielectric properties. Overall, six of the anodic oxide film prism array, each column should be filled with a solution of star shaped holes, resembling a honeycomb structure, two times the thickness of the pore diameter of the hole wall.
(1) the barrier layer is composed of anhydrous AI2O3, thin and compact, with high hardness and the function of preventing current passing. (2) a porous outer oxide film with a porous outer layer, mainly consisting of amorphous AI2O3 and a small amount of r-AI2O3.H2O, which also contain electrolyte anions.
The pore size of the oxide film is between 100nm~200nm, the thickness of the oxide film is about 10 microns, the porosity is about 20%, and the hole distance is between 300~500nm. The cross section of the oxide film shows that the oxide film hole is basically tubular and the oxide film is dissolved at the bottom of the hole. While the average pore size of the direct current anodic oxidation film is about 20nm, and if it is 12 microns of oxide film, it is a deep small tube like structure! Assuming that this is a well with a diameter of 1m, then its depth will be 600m deep.
On the most excellent properties, such as corrosion resistance, wear resistance, adsorption, insulation performance is determined by the thickness and porosity of the porous outer layer, but both are closely related with the anodizing conditions, so it can get to meet different requirements by changing the conditions of anodic film. Film thickness is an important performance indicator of anodic oxidation products. The size of the film directly affects the corrosion resistance, wear resistance, insulation and chemical coloring of the film. During the conventional anodic oxidation process, the film thickens with time. After the maximum thickness in the product, then with the prolonging of treatment time and gradually becomes thinner, some alloys such as AI-Mg, AI-Mg-Zn alloy is especially evident. Therefore, the oxidation time control within the time between maximum film thickness.
2) the properties and applications of anodic oxidation film are characterized by higher hardness and wear resistance, strong adhesion, strong adsorption ability, good corrosion resistance and electrical insulation, and high thermal insulation. Because of these special properties, it has been widely used in many fields.
The main uses are:
(1) to improve the wear resistance, corrosion resistance and weather resistance of parts.
(2) the transparent film formed by oxidation can be colored and made into various color films.
(3) as dielectric film of capacitor.
(4) to improve the adhesion with organic coatings. Make the coating bottom.
(5) the bottom of electroplating and enamel.
(6) other applications under development: solar absorption plates, ultra hard films, dry synovial membranes, catalyst films, nanowires, and magnetic alloys deposited in porous membranes as memory devices.
Sealing process
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The aluminum oxide film is a porous film. Whether or not it has been treated by coloring, it should be closed before being put into use so as to improve its corrosion resistance and weatherability. There are three kinds of treatment methods, namely, high temperature hydration reaction closure, inorganic salt sealing and organic matter sealing.
(1) high temperature water seal
This method uses the hydration reaction of aluminum oxide film and water to change the amorphous film into hydrated crystalline film:
The hydration reaction at room temperature and high temperature can be carried out, but at high temperatures especially in the boiling point, hydrated crystalline film generated is crystalline film, irreversible very stable. Therefore, the most commonly used aluminum oxide film sealing is boiling water or steam treatment method.
(2) inorganic salt sealing;
Inorganic salts can improve the fastness of organic dyes, so they are often used in chemical coloring.
The acetate method
Silicate process
(3) organic sealing method
This is the aluminum oxide film, lacquer painting or immersion, due to higher costs and increase the process, thus not using, or by two kinds of methods for the more, and in the first hydration at high temperature for the mainstream.

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