Surface treatment of spring equipment to extend service life

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 on the surface of the spring or electron gain and loss changing into an ionic state.

If the metal on the surface of the spring only reacts chemically with the surrounding medium, and the spring causes corrosion, it is called chemical corrosion. For example, the oxidation of a spring in a particularly dry atmosphere to form an oxide film, and the chemical change of the spring with the liquid or impurities in a non electrolyte liquid belong to chemical corrosion.

If the spring comes into contact with an electrolyte solution, the corrosion caused by the action of a micro battery is called electrochemical corrosion. For example, springs come into contact with acidic or salt solutions, which are electrolytes. Due to defects or impurities on the surface of the spring, electrodes with different potential differences are formed, resulting in continuous electrolytic corrosion of the spring; For example, when a spring is in a humid atmosphere, the water vapor in the atmosphere condenses into a water film or water droplet on the surface of the spring, and corrosive gases in the atmosphere (such as sulfur dioxide and hydrogen sulfide in industrial waste gas or salt mist in the ocean atmosphere) dissolve in the water film or water droplet to form an electrolyte. In addition, impurities or defects in the spring metal can also form electrodes with different potential differences, resulting in electrolytic corrosion of the spring. These are all electrochemical corrosion.

The chemical corrosion of springs is small and slow, while electrochemical corrosion is the main and common. But generally speaking, chemical corrosion and electrochemical corrosion coexist.

Springs are often subjected to corrosion from surrounding media during manufacturing, storage, and use. Due to the fact that springs rely on elastic force during operation, their elasticity will change and lose function after being corroded. So preventing corrosion of the spring can ensure its stable operation and extend its service life.

The anti-corrosion method for springs generally adopts a protective layer, which can be divided into metal protective layer, chemical protective layer, non-metallic protective layer, and temporary protective layer based on the properties of the protective layer. The first three methods are mainly introduced here.

Stainless steel springs and copper wire springs themselves have certain anti-corrosion capabilities, so they are generally not subjected to anti-corrosion treatment.