Forming a protective film: Passivation treatment forms a dense oxide film or other type of protective film on the surface of the metal. This film can effectively prevent oxygen, moisture and other corrosive media from contacting the metal matrix, thus slowing down the occurrence of corrosion reactions. For example, after passivation treatment of stainless steel, the passivation film on the surface can resist a variety of corrosive environments, such as atmosphere, seawater, acid, alkali, etc., which greatly improves its corrosion resistance in different environments.

Reduced corrosion rate: The passivation film has high chemical stability and can significantly reduce the corrosion rate of the metal. Even under harsh corrosion conditions, the passivated metal can maintain a relatively low corrosion rate and extend its service life. For example, in the chemical industry, some metal equipment can operate stably in corrosive media for a long time after passivation treatment, reducing equipment maintenance and replacement costs.

Increase the surface hardness: During the passivation process, some microstructure changes may occur on the metal surface, so that the surface hardness is improved. This makes the passivated metal more resistant to wear and scratches during use. For example, after some tool steels are passivated, the surface hardness increases, which can better maintain the sharpness of the cutting edge and improve the service life of the tool.

Improved wear resistance: Passivation film can reduce the coefficient of friction between the metal surface and other objects, reducing the degree of wear. At the same time, the passivation film itself also has a certain wear resistance, which can protect the metal matrix from wear to a certain extent. For example, the piston rings of automotive engines are usually made of materials that have been passivated to improve their wear resistance and reduce engine wear and fuel consumption.

Uniform surface color: Passivation treatment can make the color of the metal surface more uniform and beautiful. For some metal products with high appearance requirements, such as decorations, furniture hardware, etc., passivation treatment can improve the overall appearance quality. For example, stainless steel jewelry after passivation treatment, the surface shows a bright, uniform color, increasing the attractiveness of the product.

Removal of surface defects: In the passivation process, some minor surface defects, such as scratches, oxidation spots, etc., can be repaired to a certain extent. The formation of passivation film can cover these defects, making the metal surface more smooth and flat. For example, some aluminum alloy profiles after passivation treatment, the surface scratches and defects are significantly reduced, improving the quality of the product.

Easy to clean: The passivated metal surface is smoother, and it is not easy to absorb dust, dirt and other impurities. This makes the passivated metal products easier to clean and maintain good appearance and hygiene. For example, after passivation treatment, kitchen utensils, medical equipment, etc., are easy to clean and disinfect, and meet the requirements of health standards.

Prevent bacterial growth: Some passivation membranes have antibacterial properties that can inhibit the growth and reproduction of bacteria on metal surfaces. This is very important for some metal products used in health care, food processing and other fields. For example, stainless steel medical devices are passivated to reduce the risk of bacterial infection and improve medical safety.

Provide a good base: The metal surface after passivation treatment is cleaner and more uniform, providing a good basis for the adhesion of paint and coating. The paint and coating can better bond with the passivated metal surface, improving the adhesion and durability of the coating. For example, in automobile manufacturing, the body of the car is usually passivated before painting is applied to ensure that the paint can firmly adhere to the body surface, improving the appearance quality of the car and corrosion resistance.

Prevent the coating from falling off: Because the passivation film is closely combined with the metal matrix, it can effectively prevent the paint and coating from falling off and foaming during use. This extends the service life of the coating and reduces maintenance costs. For example, passivation treatment of steel structure buildings before anti-corrosion coating can improve the adhesion and anti-corrosion performance of the coating and extend the service life of the building.