Our black oxide treatment provides a durable and corrosion-resistant surface for metal parts, adding a sleek black finish and enhancing both the appearance and performance of the product.

Electrophoretic black and blackening are two common surface treatment processes with similar results, but what are the differences between the two processes? Today we will explain to you:

I. Electrophoresis

• 1. Definition: Electrophoretic paint, also known as electrophoretic coating. Electrophoresis is one of the most effective methods for coating metal workpieces. Electrophoretic coating is a special coating method in which the conductive object to be coated is immersed in a bath filled with a diluted electrophoretic coating as the anode (or cathode), and a corresponding cathode (or anode) is also provided in the bath. After a period of time, a uniform and fine coating that is not soluble in water is deposited on the surface of the object to be coated through direct current.

• 2. Classification: Electrophoretic coatings can be divided into anodic electrophoretic coatings and cathodic electrophoretic coatings according to the electrode of the workpiece to be coated; they can be classified into anionic electrophoretic coatings and cationic electrophoretic coatings according to the ionic form of the film-forming material in water.

• 3. Applications: It can be divided into anodic electrophoretic paint and cathodic electrophoretic paint. Among them, anodic electrophoretic paint has acrylic anodic electrophoretic paint, which is mainly used for aluminum products. After oxidation of aluminum, anodic electrophoretic paint is used for protection, with a glossiness between 50-90 degrees and a thin film. It is widely used in the aluminum profile industry. Cathodic electrophoretic paint can be further divided into: epoxy electrophoretic paint, acrylic electrophoretic paint, and polyurethane electrophoretic paint. Epoxy electrophoretic paint: It has ultra-strong salt spray performance and deep-hole penetration. On phosphating substrates, the salt spray performance can reach more than 1000 hours. Its main products are bright black, matte black, dark gray and light gray. Red, green, and some colors are also used. Epoxy electrophoretic paint is a coating that can cover the substrate, mainly used for primer corrosion protection and can also be used as a general hardware component topcoat. Acrylic and polyurethane electrophoretic paints: have ultra-strong weather resistance, QUV yellowing resistance, and high transparency (85-90 degrees). They are mainly used for coating protection, and special color paste can be added for color mixing, providing bright and vivid color, and improving salt spray resistance for directly electrophoretic plating in hardware components.

• 4. Characteristics: Advantages. As a new type of low-pollution, energy-saving, resource-saving, protective and anticorrosive coating, electrophoretic coatings have the characteristics of a flat coating, good water resistance, and good chemical resistance. It is easy to realize the mechanization and automation of coating industry and is suitable for complex shapes and workpieces with edges, corners, and holes.

Limitations:
1. Electrophoresis must be performed under energized conditions, so it is suitable for conductive objects (generally metal) to be coated.
2. When coating objects made of multiple metals with different conductive properties, electrophoretic coating technology should not be used. Some electrophoretic coatings can cause allergic reactions to metal ions such as Cu and Sn.
3. The wet electrophoretic coating must be baked to form a dense film, so electroplating parts that cannot withstand high temperatures cannot be coated with electrophoresis.
4. The electrophoresis tank needs to be replaced within 6 months, so electrophoretic coating is not suitable for small-scale production.
5. The performance of electrophoretic coatings on different substrates varies.
6. Strong technical skills are required to support them, especially for color electrophoresis, which is difficult for non-professionals to achieve the expected color effects when blending colors.

II. Blackening

• 1. Principle: Blackening treatment is a chemical surface treatment, which mainly forms a dense oxide film on the surface of the workpiece to prevent corrosion and improve wear resistance. It is only a surface treatment and will not affect the internal structure.
• 2. Process:
1. Cleaning;
2. Degreasing: The workpiece must be completely immersed in a degreasing solution; the concentration of the degreasing solution is pH 12-14, and the treatment time is 10-30 minutes. Every 3-5 minutes, shake it up and down a few times. Add degreasing powder when the concentration of the medicine is less than pH 12;
3. Rinse with water;
4. Pickling: The concentration of the pickling solution is pH 2-4, and the treatment time is 5-10 minutes;
5. Rinse with water;
6. Blackening: The concentration of the bath solution is pH 2.5-3.5, and the treatment time is 10-12 minutes;
7. Rinse with water;
8. Dry with hot air;
9. Oil application.
• 3. Characteristics:

Advantages: simple process, low cost, rust prevention.

Disadvantages: environmental pollution, unstable process.

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