Why do springs need to be electroplated, what to do after electroplating, and what are the effects of electroplating? I believe that everyone has not found a suitable answer after seeing these questions. Most people think that galvanizing is just for beauty, but everyone does not know about galvanizing. In addition to aesthetics, there are other functions. Here is a brief description of why the spring is galvanized!
1. Why should the spring be galvanized?
(1) Generally, the galvanized layer is passivated after plating. Passivation can improve the protective performance of the coating and increase the appearance of the surface.
(2) The thickness of zinc and cadmium coatings determines the level of protection. The thickness should generally be selected according to the working environment during use. The thickness of the zinc coating is recommended to be selected within the range of 6-24/μm; the thickness of the cadmium coating is recommended to be selected within the range of 6-12/μm.
(3) The zinc and cadmium plating of the spring is carried out in the cyanide electrolyte. In the electroplating process, in addition to the zinc or cadmium plating, a part of the reduced hydrogen penetrates into the crystal lattice of the plating layer and the base metal. , Causing internal stress, making the coating and the spring brittle, also called hydrogen embrittlement.
(4) Due to the high strength of the spring material and the large deformation of the spring during forming, it is particularly sensitive to hydrogen embrittlement. If the hydrogen is not removed in time, it will often cause the spring to break. In order to eliminate the occurrence of the electroplating process For some defects, to improve the physical and chemical properties of the spring, prolong the service life of the spring, and increase the corrosion resistance of the coating, post-plating treatment must be carried out, that is, hydrogen removal treatment.
(5) The hydrogen removal treatment is carried out immediately or within a few hours after electroplating. Heat the electroplated spring at a temperature of 200-215°C for 1 to 2 hours (or more than 2 hours) to achieve the purpose of hydrogen removal.
2. What is the function of the electroplating protective layer of the spring?
(1) There are many types of metal protective layers. For springs, electroplating is generally used to obtain metal protective layers. The electroplated protective layer can not only protect from corrosion, but also improve the appearance of the spring. Some electroplated metals can also improve the working performance of springs, such as increasing surface hardness, increasing wear resistance, improving thermal stability, and preventing radiation corrosion. But if it is purely for the corrosion of the spring, the electro-galvanized layer and the electro-cadmium layer should generally be used.
(2) Zinc is relatively stable in dry air, hardly changes, and is not easy to change color. A white film of zinc oxide or carbon zinc carbonate is formed in humid air. This dense film prevents further corrosion. Therefore, the galvanized layer is used as the anti-corrosion protection layer of the spring under normal atmospheric conditions. Zinc coating is not suitable for springs that are in contact with solutions such as sulfuric acid, hydrochloric acid, caustic soda, and working in humid air such as sulfur trioxide.
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