The corrosion of springs can be divided into chemical corrosion and electrochemical corrosion according to the type of reaction. They are all the result of changes in metal atoms or electron gains and losses on the surface of the spring.
If the metal on the surface of the spring simply reacts chemically with the surrounding medium, the corrosion caused by the spring is called chemical corrosion. For example, the spring oxidizes to form an oxide film in a particularly dry atmosphere, and the spring in a non-electrolyte liquid chemically changes with the liquid or impurities in the liquid, etc., which are chemical corrosion.
If the spring comes into contact with the electrolyte solution, the corrosion caused by the action of the microbattery is called electrochemical corrosion. For example, the spring is in contact with an acid or salt solution. These solutions are electrolytes. Due to defects or impurities on the surface of the spring, electrodes with different potential differences are formed, so that the spring is continuously subject to electrolytic corrosion. Water vapor in the atmosphere condenses into a water film or water droplets on the surface of the spring, and corrosive gases in the atmosphere (such as sulfur dioxide and hydrogen sulfide in industrial exhaust gas or salt mist in the marine atmosphere) are dissolved in the water film or water An electrolyte is formed in the beads. In addition, impurities or defects in the spring metal can also form electrodes with different potential differences, and the spring also produces electrolytic corrosion. These are all electrochemical corrosion.
Chemical corrosion of springs is small and slow, while electrochemical corrosion is predominant and widespread. Generally speaking, chemical corrosion and electrochemical corrosion coexist.
Springs are often subject to corrosion from surrounding media during manufacturing, storage, and use. Because the spring works by spring force, the spring force will change and lose its function after the spring is corroded. Therefore, preventing the corrosion of the spring can ensure the stability of the spring and extend its service life.
Spring anti-corrosion methods generally use a protective layer, which can be divided into: metal protective layer, chemical protective layer, non-metal protective layer, and temporary protective layer according to the nature of the protective layer. The first three methods are emphasized here.
Stainless steel springs and copper wire springs have a certain anti-corrosion ability, so they are generally not treated with anti-corrosion.
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