Anodizing

1. Basic principle

During the anodizing process, aluminum products are immersed in a solution containing sulfuric acid or other electrolytes, and an electrical current is applied, making the aluminum the anode (positive terminal). When current passes through the solution, an oxidation reaction occurs on the aluminum surface, forming an aluminum oxide (Al₂O₃) layer. This oxide layer is dense and provides excellent corrosion and wear resistance.

2. Types of Anodizing

Standard Anodizing: Conducted in general electrolytes, suitable for typical applications, providing basic corrosion resistance and hardness.

Hard Anodizing: Uses low temperatures and high voltage to create a thicker, harder oxide layer, used for industrial parts requiring high strength and wear resistance.

Color Anodizing: Uses dyeing techniques to introduce color into the oxide layer after anodizing, widely used for decorative products.

3. Advantages of Anodizing

- Enhanced Corrosion Resistance: The oxide layer protects the metal from environmental exposure, effectively preventing corrosion.
- Increased Hardness and Wear Resistance: The oxide layer strengthens the surface and reduces wear.
- Improved Adhesion: After anodizing, paints and adhesives adhere more strongly to the surface.
- Aesthetic Appeal: The oxide layer can be dyed in various colors, providing a range of aesthetic options and enhancing product appearance.

4. Types of hard anodizing:

1. Low-Temperature Hard Anodizing

Characteristics: Conducted at lower temperatures (typically between -5°C and 5°C) to increase oxide layer density and hardness.

2. Thick-Film Hard Anodizing

Characteristics: The oxide layer is thicker than standard hard anodizing, usually reaching 50 to 100 microns or even more.

Types of hard anodizing:

3. Black Hard Anodizing

Characteristics: Involves a dyeing process after hard anodizing, resulting in a black appearance.

4. Micro-Arc Oxidation Hard Anodizing

Characteristics: Uses high-voltage pulse discharge to create a ceramic-like oxide layer.

Application of Anodizing

Common Application

In summary, anodizing is an efficient and economical surface treatment technique that significantly enhances the performance and appearance of aluminum and its alloys, making it a vital technology in modern industries.

Used in aircraft bodies, wings, and internal structures to enhance corrosion resistance and wear resistance, extending the parts’ lifespan and reducing maintenance needs.

Applied to aluminum components in cars, such as engine pistons, radiators, and wheels, to improve durability, oxidation resistance, and add an aesthetic appearance.

Commonly used in aluminum casings for consumer electronics like smartphones and laptops; anodizing enhances scratch resistance, durability, and allows for attractive color options.

Aluminum doors, windows, curtain walls, and decorative panels benefit from anodizing, which increases weather resistance, corrosion protection, and keeps their appearance vibrant over time.

Utilized for surgical instruments and dental tools, anodizing provides enhanced antimicrobial and corrosion-resistant properties, while reducing metal surface reflections to improve surgical precision.

Anodized aluminum mixers, containers, and other food-contacting equipment form a non-toxic protective layer that prevents food residue and chemical reactions, meeting food safety standards.