The Application of Aluminum Anodizing

　　The technique of aluminum anodizing applied widely on industry can be used to prevent the aluminum products from corrosion, protection and decoration, such as being applicable to wear-resisting layer, electrical insulation layer, bottom layer of painting and electroplated bottom layer.

１.Preventing aluminum products from corrosion

　　The oxidation film on the surface of aluminum can be used as protective layer because the film layer of anodizing is stable sufficiently in the atmosphere. The oxidation film has the good compactness and corrosion fastness when the aluminum is anodized in the chromic acid solution. The pore on oxidation film caused by the sulfuric acid solution is bigger than those in the chromic acid solution but the film layer is thicker and has the strong absorbability. Furthermore, the film layer’s corrosion fastness is outstanding after the appropriate process of filling and sealing. Particularly, chromic acid anodizing is specifically applicable to the anodizing of riveted parts and weldments work.

２.Protection and decoration for products

　　For the aluminum and its alloy products that are mostly required with the surface finishing, those oxidation film’s transparency can be higher when even being anodized with sulfuric acid solution after the process of chemical and electrochemical polish. This type of oxidation film can absorb plenty of organic and inorganic dyes so the diversified bright color can be created. The color film is not only the anti-corrosion layer, but also the decoration layer. With some specific process conditions, the protective and decorative oxidation film whose appearance is as similar as the porcelain can come into being.

３.As the hard wear-resisting layer

　　Through the hard anodizing on the aluminum and aluminum alloy, it can create thickness and strong AI2O3 film layer on the surface, not only increase hardness and thickness of this film layer has, but also the lower roughness. The thick and strong oxidation film can be also created on the aluminum products by anodizing in the sulfuric acid or oxalic acid.The thick oxidation film with pores can reserve lubrication oil, therefore, it can be effectively applied to the aluminum products running at the friction state, for example, those vehicles and tractors’ engine cylinders, piston, etc. can be enhanced their wear-resistance significantly.

４.As the electrical insulation layer

　　After anodizing, the acquired oxidation film of aluminum and aluminum alloy products has the higher electric resistance. Consequently, it is useful for enhancing the certain products’ electrical insulation. Additionally, anodizing can be used to create capacitance’s dielectric layer and the aluminum oxide can be also used to create the insulated layer for the surface.

５.As the bottom layer of painting

　　With the anodizing film’s porosity and good absorbability, it can be utilized as the bottom layer of painting and organic film, which let’s the painting film, organic film to be combined with products strongly, and enhance the corrosion fastness as result.

６.As the electroplated bottom layer

　　Before the aluminum and aluminum alloy products are electroplated, the bottom layer must be required. There are plenty of methods of applying the bottom layer on the matrix surface, such as electro galvanizing, zinc galvanizing and electroless nickel plating, anodizing another one of the important methods is anodizing processing.

　　In addition to being generally used on industry, anodizing is also needed extensively on other scientific areas, especially the advance electronic industry. In future, the technique of aluminum anodizing processing will be applied on more aspects. 

< BACK >