What is the surface treatment process of Black Zinc Hexagonal Screw?

In modern manufacturing, the surface treatment of screws is crucial. It is related to the appearance of the product and affects its corrosion resistance and service life. As a widely used fastener, the surface treatment process of black zinc hexagonal screws is particularly important. The following will explore the surface treatment process of black zinc hexagonal screws in depth, including its process steps, material selection and its advantages and disadvantages.

1. Material selection
Black zinc hexagonal screws usually use high-quality carbon steel or stainless steel as the substrate. These materials have good mechanical properties and corrosion resistance. Before surface treatment, it is necessary to ensure that the surface of the screws is clean so that the subsequent treatment effect is the best.

2. Cleaning and degreasing
Before any surface treatment, the screws need to be cleaned first. This step usually uses solvent cleaning or alkaline cleaning to remove oil, rust and other impurities on the surface of the screws. The cleaned screws must be thoroughly dried to avoid affecting the subsequent treatment effect.

3. Galvanizing treatment
The main surface treatment process of black zinc hexagonal screws is galvanizing. Galvanizing can be done by electroplating or hot-dip galvanizing, but electroplating is more common. The specific steps are as follows.
Electroplating preparation: Soak the cleaned screws in an electroplating tank containing a zinc salt solution.
Electroplating process: The zinc ions are reduced and deposited on the surface of the screws through an electric current to form a uniform zinc film. The zinc plating thickness is usually 5-15 microns, which can effectively prevent corrosion.

4. Black treatment
In order to obtain a black appearance, black treatment is usually performed after galvanizing. This process usually involves the following steps.
Blackening treatment: Through chemical reactions, the surface of the zinc film is converted into a black compound. Common methods include sodium hydroxide and sulfide treatment.
Post-treatment: After blackening, the surface of the screw is coated with a protective oil film to further improve its corrosion resistance.

5. Quality inspection
After completing the surface treatment, strict quality inspection must be carried out. The main inspection items include.
Plating thickness: Use special instruments to measure the thickness of the zinc plating layer to ensure that it meets the standards.
Adhesion test: Check the adhesion of the coating to the substrate through methods such as tape testing.
Appearance inspection: Observe the surface of the screw to ensure that there are no flaws and defects.

6. Packaging and storage
When packaging the surface-treated black zinc hexagon screws, attention should be paid to moisture-proof and damage-proof. Usually, moisture-proof bags or cartons are used for packaging to avoid being affected by the external environment during transportation and storage.

The surface treatment process of the black zinc hexagon screws improves its aesthetics, corrosion resistance and service life. Through the fine cleaning, galvanizing and black treatment process, this screw can maintain good performance in various harsh environments. When choosing black zinc hexagon screws, understanding its surface treatment process can help users better evaluate its applicability and reliability.