Spring surface rust treatment
Most springs work in varying degrees of corrosive environment, and due to chemical and electrochemical effects, the surface of the material is corroded and the spring is damaged prematurely, so it must be treated with corrosion.
Spring anti-corrosion treatment is covered with anti-corrosion material on the spring surface, the formation of protective layer, the protective layer will be separated from the corrosive media spring to achieve the purpose of anti-corrosion.
Commonly used spring anti-corrosion methods are three: electroplating, oxidation, painting.
Electroplating is an effective way to obtain a metal surface protective layer and is the main method of spring anti-corrosion treatment. It is characterized by good adhesion of the coating, fine crystal closely, low porosity, uniform thickness, good physical, chemical and mechanical functions.
Electroplating with galvanized, chrome, copper, tin and nickel plating, the most common application is galvanized.
Spring galvanized surface is generally white or color. Zinc in the dry air almost no change. In the humid air or carbon dioxide containing water will produce zinc oxide white film, this layer of film can play a role in corrosion inhibition. The galvanized layer is suitable for use in a variety of atmospheric conditions, but the corrosion resistance of zinc is poor in aqueous solutions containing acids, bases and salts and in purely marine atmosphere.
Galvanized features are low cost, simple process, the effect is better, it is widely used in the atmosphere using small and medium-sized anti-corrosion spring.
Spring galvanized after passivation and dehumidification to improve the anti-corrosion ability of the spring and to avoid hydrogen embrittlement. Especially small springs are more prone to hydrogen embrittlement, in the pickling and plating must pay special attention.
The oxidation of the spring is also called blue or black. After oxidation, the surface of the spring produces protective magnetic iron oxide, the thickness of about 0.6 ~ 2um. As the film thin and multi-gap, poor protection. So the oxidation process can only be used in the corrosive medium is not working in the spring anti-corrosion.
Due to the low cost of oxidation treatment, simple process formula, high production efficiency, does not affect the characteristics of the spring, it is widely used in cold forming small spring surface corrosion.
In addition to oxidation treatment, there are phosphating treatment. Phosphating film is more stable under atmospheric conditions. Its corrosion resistance than the oxidation process 2-10 times higher.
Painting is also one of the main methods of spring corrosion. Mostly used in large, medium-sized springs. Especially thermoformed springs and plate springs. For the spring paint are: asphalt paint, phenolic paint and epoxy paint. Some important springs, in order to improve the adhesion of paint and anti-corrosion ability, but also take the first post-phosphate coating process.
Commonly used painting method is painting and dipping, with the development of technology, in order to improve work efficiency, paint utilization and paint the quality, will promote the new technology such as electrostatic spraying.
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