Aluminum coil anodizing is an electrochemical process that forms an aluminum oxide film on the surface of the aluminum coil. The main process is as follows:
Pretreatment: This is a crucial preparatory stage. First, degreasing is performed using an alkaline solution to remove oil, dirt, and impurities from the aluminum coil surface, ensuring smooth subsequent processing. Next, pickling is performed using an acidic solution to remove the natural oxide layer and other residues on the aluminum coil surface, leaving the aluminum coil with a clean metal surface. After degreasing and pickling, the aluminum coil is rinsed with water to remove any remaining chemicals on the surface, preparing it for anodizing.
Anodizing: The treated aluminum coil is hung on a special fixture and placed in an electrolytic cell containing sulfuric acid, oxalic acid, or another electrolyte. The aluminum coil acts as the anode, and a metal plate (usually a lead plate) serves as the cathode.
When electricity is applied, a complex electrochemical reaction occurs on the surface of the aluminum coil, controlled by specific parameters such as the electrolyte, temperature, current density, and treatment time.
A dense aluminum oxide film is gradually formed. This film forms and dissolves simultaneously, and only when the film formation rate exceeds the dissolution rate can the film continue to grow thicker.
Sealing: After anodizing, the oxide film needs to be sealed. Common sealing methods include hot water sealing, steam sealing, and chemical sealing. Sealing aims to enhance the corrosion and wear resistance of the oxide film, further improving the performance of the anodized aluminum coil.
Post-treatment: After sealing, the aluminum coil is rinsed again with water to remove excess electrolyte and sealant from the surface. Finally, it is dried. The anodized aluminum coil is now ready for the next process or for direct packaging and storage.
Anodized aluminum coils come in a wide variety of colors, including white, black, gray, solid/single color, silver gray/silver flash, gold, champagne gold, rose gold, natural/natural color, and titanium. Furthermore, through specialized processes, high-gloss, matte, two-tone, and three-tone finishes can be achieved. In addition to these standard colors, aluminum coils can also be customized to suit customer needs.
Improved Hardness and Wear Resistance: After anodizing, the aluminum oxide film formed on the surface of the aluminum coil significantly increases its hardness, reaching gem-grade levels, and significantly enhances its scratch resistance.
Excellent Heat Resistance: The hard oxide film has a very high melting point, allowing it to withstand high temperatures and maintain stable performance even in high-temperature environments.
Enhanced Corrosion Resistance: Anodized aluminum coils remain corrosion-free for thousands of hours in harsh environments like salt spray.
Adsorption and Colorability: The thin oxide film contains numerous micropores with strong adsorption capacity, capable of absorbing not only various lubricants but also organic dyes, resulting in a variety of beautiful and vibrant colors, greatly enhancing the decorative value of the aluminum coils for sale.
Architectural Decoration: It is widely used in metal aluminum ceilings, curtain wall panels, aluminum-plastic panels, fireproof panels, cabinet panels, furniture panels, etc.
Mechanical and Automotive Components: Due to its high hardness, excellent wear resistance, and strong corrosion resistance, it is suitable for manufacturing engine cylinders, mechanical parts, aircraft and automotive components. In automotive manufacturing, anodized aluminum coils are used in the manufacture of automobile wheels and interior trims.
Other Industries: It is also widely used in lighting, handicrafts, signage, interior decoration, precision instruments, and radio equipment.