How does aluminum anodizing metal surface treatment become color diversity?
Publish Time: 2025-02-11
As an advanced metal surface treatment technology, aluminum anodizing not only significantly enhances the corrosion resistance, hardness and wear resistance of aluminum and its alloys, but also brings it a rich color selection. This technology forms a dense aluminum oxide film on the aluminum surface through an electrochemical process, and this film is the key to achieving color diversity.
In the anodizing process, aluminum is placed in a solution containing a specific electrolyte as an anode, and an oxidation reaction is initiated by applying voltage. This reaction causes a porous aluminum oxide film to form on the aluminum surface, which has a sponge-like structure and has a very high adsorption capacity. It is this porous film that makes subsequent coloring treatment possible.
The realization of color mainly depends on two ways: natural color anodizing and colored anodizing. Natural color anodizing is to control the naturally formed color of the aluminum oxide film by adjusting the composition and oxidation conditions of the electrolyte solution, such as the type of electrolyte (sulfuric acid, oxalic acid, etc.), temperature, voltage and time. For example, the oxide film formed in sulfuric acid electrolyte is usually silvery white, while in oxalic acid electrolyte it may form golden yellow.
In order to obtain more diverse colors, colored anodizing technology came into being. This technology adds metal salts or organic dyes to the electrolyte solution during the oxidation process. These additives are adsorbed and embedded in the porous structure of the aluminum oxide film under the action of the electric field. As the oxidation reaction proceeds, these additives react chemically or physically adsorb with the aluminum oxide film to form stable color compounds. By precisely controlling the type, concentration and oxidation conditions of the additives, the color can be precisely controlled to achieve a variety of color changes from basic tones such as black and gold to complex colors such as red, blue, and green.
It is worth noting that the colored aluminum oxide film also needs to be sealed to improve its weather resistance and color stability. The sealing treatment is usually carried out by soaking in hot water, steam or a specific sealant, aiming to seal the pores of the aluminum oxide film and reduce the intrusion of external pollutants, thereby maintaining the lasting and bright colors.
The color diversity of aluminum anodizing technology not only meets the needs of different industries for aesthetics, but also provides designers with a broader creative space. From aerospace, automobile manufacturing to consumer electronics, architectural decoration, aluminum anodizing technology has become an indispensable part of modern industrial design with its unique aesthetic effects and excellent performance.
