What are the technologies for aluminum surface treatment?

The material composition of aluminum products before the aluminum surface treatment is oxidized, and the influence of purity on the quality of aluminum oxide film has long been understood by scientific and technological workers. However, in industrial production, the surface processing quality of domestic aluminum products seriously affects the quality of anodizing products, and this contradiction is becoming more and more prominent. Foreign aluminum products are milling surface treatment, smooth as a mirror, excellent quality after oxidation.

In China, aluminum is often not high gloss, bubbles, scratches, heavy skin rough phenomenon is very serious, after anodizing treatment, these defects are still revealed. Decorative processes such as a variety of pattern printing, heat transfer printing, etc. due to the poor surface state of plate quality and resulting in poor results are particularly serious. Therefore, improving the appearance quality of the plate has become an important part of ensuring the best quality of aluminum products.

Sulfuric acid method, oxalic acid method, chromic acid oxidation process, especially sulfuric acid anodizing method, is almost unknown to every person engaged in aluminum surface treatment of aluminum products. These oxidation methods have their own characteristics and scope of application, such as oxalic acid method, can obtain a thicker oxide film, the oxide film itself with some decorative color, but the cost of this method is high, the consumption of electric energy.

Sulfuric acid oxidation film transparent colorless, good color absorption performance, plus the electrolyte composition is simple and stable, easy process operation, low cost, so it is more widely used, but the sulfuric acid process temperature control range is small, fast temperature rise, often need to install freezing equipment, which has become a difficulty. In Japan, the mixed acid oxidation method of sulfuric acid-oxalic acid has long been developed, taking the advantages of both and avoiding the disadvantages of both, and becoming the main oxidation tank solution in Japan. China's Shenyang aluminum products factory introduced the use of mixed acid oxidation technology, they recommend the formula is: sulfuric acid 10 ~ 20%; Oxalic acid 1-2%; Dc voltage 10 ~ 20 volts; Anodizing.

After oxidation, many aluminum products are also dyed or printed spray aluminum surface treatment, in order to get a variety of bright colors or beautiful patterns, increase the variety of fancy. In 1980, the transfer printing method of aluminum products identified by the Ministry of Light Industry can obtain a variety of color patterns with clear patterns, bright colors and full layers. The transfer printing method of aluminum products is also called sublimation transfer color process, its basic principle is to use dispersed dyes specially made transfer ink, printed on paper according to the pattern requirements, made of color printing paper, and then the printed paper is attached to the oxide film of aluminum products, through heating and hot pressing, so that the disperse dye on the printed paper into a gas phase transfer to the oxide film micropores, forming a color pattern.

The transfer printing method makes the surface of aluminum products obtain color images by its technology beyond the traditional oxidation dyeing method, which attracts the attention of many aluminum products manufacturers to test and produce. Shanghai, Wuhan, Qingdao and other aluminum products factories have been put into industrial production. At this stage, the process cost is still high, the manufacture of transfer printing paper to rely on the printing industry, high temperature pressure transfer color patterns are mostly still in the manual operation stage. The mechanism of printing transfer has not been thoroughly discussed in theory. More people think that mainly under high temperature heating conditions, the disperse dyes in the transfer ink sublimate to the oxide film.

However, some test results of aluminum surface treatment show that the thickness and adsorption properties of the oxide film also play a very important role, so it is not simply a simple sublimation phenomenon of disperse dyes. It is believed that with the continuous exploration of the transfer mechanism, the continuous improvement of the application process and the accumulation of experience, the transfer printing method will open up a broad new field for the beautification and decoration of aluminum products.