Electrolytic Oxidation Decorative Hard Anodized Aluminum Metal Surface Cnc

Product Specification

Anodized Aluminum Parts Electrolytic Oxidation for Protective and Decorative Coating Anodizing Aluminum Electrolytic Oxidation Metal Surface Treatment Process

Definition of Anodizing Aluminum Alloys

Anodizing aluminum alloys is an electrochemical surface treatment technology that involves placing aluminum alloys in an electrolyte solution and using them as an anode for electrolytic processing. This process leads to the formation of a dense oxide film on the surface of the metal. Not only does this enhance the surface hardness, wear resistance, and corrosion resistance of the metal, but it also provides diverse colors and gloss effects on the metal surface. Specifically, when aluminum is used as the anode in acidic electrolyte solutions such as sulfuric acid or oxalic acid and a direct current is applied, oxidation reactions occur on the surface of the aluminum, resulting in the creation of an aluminum oxide film.

Anodizing aluminum is an electrolytic oxidation process wherein the surface of aluminum and aluminum alloys is typically transformed into a layer of oxide film. This oxide film has protective, decorative, and various functional characteristics. The oxide film consists of numerous micropores that can adsorb various lubricants, making it suitable for manufacturing engine cylinders or other wear-resistant parts. The high adsorption capacity of the micropores allows for coloring into a variety of aesthetically pleasing hues. Non-ferrous metals or their alloys, such as aluminum, magnesium, and their alloys, can all undergo anodizing treatment. This method is widely used in mechanical parts, aircraft and automobile components, precision instruments and radio equipment, daily necessities, and architectural decorations.

Processes of Anodizing Aluminum Alloys

Common processes for anodizing aluminum alloys include sulfuric acid anodizing, chromic acid anodizing, oxalic acid anodizing, and phosphoric acid anodizing. The most commonly used process is sulfuric acid anodizing.

Why is Sulfuric Acid Anodizing Widely Used for Aluminum Alloys?

Sulfuric acid alternating current anodizing has low current efficiency, poor corrosion resistance, and low hardness, which is why it is rarely used. The predominant method used both domestically and internationally is sulfuric acid direct current anodizing. Compared to other acidic anodizing methods, sulfuric acid anodizing has the following significant advantages in terms of production cost, characteristics, and performance of the oxide film:

①Low Production Cost: The sulfuric acid used in the electrolyte is inexpensive, the power consumption for electrolysis is low, and the waste liquid treatment is simple. Overall, this process is the most cost-effective compared to other anodizing methods.

②The film has high transparency. Generally, the sulfuric acid oxide film is colorless and transparent, and the purer the aluminum, the better the transparency of the film. The alloy elements Si, Fe, and Mn will reduce the transparency, but Mg has no effect on the transparency. It is most suitable for bright anodizing after polishing.

③Good corrosion resistance and wear resistance. Aluminum and aluminum alloy sulfuric acid anodizing film has excellent corrosion resistance in various atmospheres and CASS tests.

④Easy electrolytic coloring and chemical dyeing. The sulfuric acid oxide film is porous (the average porosity is 10% to 15%), colorless and transparent, and is not affected by the original color. During the electrolytic coloring process, metal ions can precipitate from the bottom of the pores and color, making the color beautiful, light-resistant and weather-resistant; in chemical dyeing, the porous film has strong adsorption, which makes it easy for the dyeing liquid to penetrate into the membrane pores, and chemical or physical reactions occur, which can be dyed into various bright colors. At present, most aluminum alloy decorative parts are basically made by this method.