The reason why the spring is galvanized and corrosion-resistant is that many users like to choose galvanized springs when selecting springs. This is not only because the galvanized appearance is more beautiful, but also because the galvanized steel wire can be prevented from being oxidized and rusted. The following Guoyang spring will elaborate on the reason why the spring is galvanized and corrosion-resistant.
In the marine or high-temperature atmosphere, as well as the springs in contact with seawater, and the springs used in 70 ℃ hot water, cadmium is relatively stable and has strong corrosion resistance. Cadmium coating is brighter and more beautiful than zinc coating, soft in quality, better in plasticity than zinc coating, and less in hydrogen brittleness. It is suitable for spring as a protective layer. However, cadmium is rare and expensive, and cadmium salt is toxic, which causes serious environmental pollution. Therefore, it is limited in use. Therefore, most springs used in aviation, navigation and electronic industry only use cadmium plating as the protective layer.
In order to improve the corrosion resistance of cadmium coating, passivation treatment can be carried out after plating. The thickness of zinc and cadmium coating determines the protection ability. The thickness shall generally be selected according to the working environment during use, and the thickness of galvanized layer is recommended to be selected within the range of 6-24mm; The thickness of cadmium plating layer is recommended to be selected within the range of 6-12mm.
There are many kinds of metal protective layers. As far as springs are concerned, plating is generally used to obtain the metal protective layer. The plating protective layer can not only protect the spring from corrosion, but also improve the appearance of the spring. Some electroplating metals can also improve the working performance of springs, such as improving surface hardness, increasing wear resistance, improving thermal stability, and preventing radiation corrosion. However, if it is only for the corrosion of the spring, the galvanizing layer and the cadmium plating layer should be generally selected.
Zinc is relatively stable in dry air, hardly changes and is not easy to change color. A white thin film of zinc oxide or carbon type zinc carbonate will be formed in the humid air. This dense film prevents further corrosion. Therefore, the galvanized layer is used as the anti-corrosion protection layer of the spring under general atmospheric conditions. Zinc coating shall not be used for springs in contact with sulfuric acid, hydrochloric acid, caustic soda and other solutions and working in humid air with sulfur trioxide and other atmospheres.
