How Does Black Anodizing Work and Treat?

The process of black anodizing is similar to conventional anodizing, but there are differences in the selection of electrolytes and the control of electrolysis conditions.

Usually, special additives are added to the electrolyte used in black anodizing to control the color and hardness of the oxide film. Controlling the electrolysis conditions is also a key factor in achieving the desired black anodizing effect. Usually, black anodizing requires higher voltage and longer electrolysis time to form a thicker oxide film. However, excessive voltage and prolonged electrolysis can lead to defects such as white spots and pores on the surface of the oxide film.

The following are the steps commonly used for black anodizing:

1, Pre treatment

Clean metal surface: Before starting treatment, ensure that the metal surface is clean and free of grease, dirt, or other impurities. This usually involves using alkaline or acidic cleaning agents to clean metals.

Pickling: Sometimes, after cleaning, the metal may need to undergo a pickling process to remove oxide layers and other unwanted materials from the surface. This can be achieved using an acidic solution.

2, Anodizing

Immersing metal components into an electrolyte solution containing an oxidant. The metal sheet itself acts as the anode (positive electrode), while the auxiliary electrode acts as the cathode (negative electrode). By applying an electric current, the oxidant triggers an oxidation reaction on the metal surface, forming an oxide film. This type of membrane is usually a variant of alumina (Al2O3). Control the current density and processing time to ensure the desired oxide film thickness is achieved.

3, Coloring

To achieve black anodizing, it is usually necessary to introduce dyes or pigments onto the oxide film. This can be achieved through impregnation, spraying, or other methods.

4, Sealing treatment

After completing the above steps, it is usually necessary to seal the oxide film to improve its stability and durability. Sealing usually involves soaking the metal sheet in a sealing agent to close the pores of the oxide film and prevent the intrusion of moisture and other substances.

5, Cleaning and drying

It is necessary to clean the treated metal parts to remove any residual treatment agents or impurities. Afterwards, it is necessary to thoroughly dry the metal to ensure the quality and stability of the oxide film.

The principle of black anodizing is based on electrochemical and redox reactions. By controlling parameters such as current density, processing time, electrolyte composition, and dye selection, the color and performance of the oxide film can be adjusted. This process is commonly used to improve the appearance and performance of metal parts, such as enhancing their corrosion resistance and wear resistance.

Black anodizing is an important surface treatment method that has advantages in high hardness, wear resistance, corrosion resistance, and aesthetics. It has a wide range of applications, covering various fields, including aviation, automotive, and electronic products. With the continuous progress of technology, black anodizing technology is also constantly developing. It is believed that in the near future, black anodizing will have more widespread applications and more refined processes.