What Is Aluminum Anodizing?
Aluminum anodizing is a surface treatment method that produces an oxide film on the aluminum surface.
Aluminum anodizing protect the aluminum surface from corrosion, scratches, and friction.
However, because the naturally formed oxide film is very thin, it can corrode through chemical reactions with other substances. In addition, aluminum is a soft material and its surface is easily scratched. Therefore, the aluminum is anodized to form a thick and durable oxide film.
The aluminum oxide that serves as the surface film is called passivity. Once aluminum oxide is formed, it has a property that does not change, thus protecting the inner aluminum and making the aluminum more resistant to corrosion.
Uses of Aluminum Anodizing
Anodized aluminum becomes more resistant to scratches and friction due to its higher corrosion resistance, abrasion resistance, and hardness. In addition, when dyes are adsorbed on the oxide film-formed surface, a variety of colors can be applied, thus beautifying the appearance.
Aluminum is used for cooking utensils such as pots, kettles, and bats because of its high thermal conductivity, light weight, and portability. In addition, because of its high workability, it is also used for construction materials such as doors and sashes that are used outdoors for a long time, and for industrial parts such as automobiles, trains, and airplanes. It is often used in products that are used outdoors.
Principle of Aluminum Anodizing
Anodizing (anodic oxidation treatment) forms an oxide film on aluminum through electrolysis in an electrolytic solution (sulfuric or oxalic acid). When the product to be treated is attached to the anode side and energized, oxygen is generated by electrolysis and forms a film on the aluminum surface.
During anodizing, the oxidation reaction and the dissolution reaction of sulfate ions occur simultaneously on the aluminum substrate. Numerous micropores are formed in the formed film, and the pores are regularly extended.
Pressurized steam, hot water, or metallic salts are used for sealing treatment. By combining electrolytic conditions such as electrolyte type, concentration, current density, and temperature, as well as the type of aluminum alloy, colors such as silver, black, gold, and amber can be produced, and hard coatings can be created to improve wear resistance.
The oxide film formed by aluminum anodizing are insulating and does not conduct electricity. For this reason, it is used in electronic devices and semiconductor manufacturing equipment that require voltage resistance. In addition, it is used in a wide range of fields such as industrial products, building materials, household goods, decorations, and transportation equipment, taking advantage of its corrosion resistance and water repellency properties.