Oxidation treatment on the surface of extension springs
Fixing of extension springs model extension springs Some customers will require extension springs to be corrosion-resistant and bright in appearance, so they will require spring manufacturers to oxidize extension springs.
The oxidation treatment of extension springs (also known as bluing, blacking, boiling black, etc.) is mainly used to prevent corrosion of the spring and also make the spring look bright. The oxidation treatment methods include: alkaline oxidation, alkali-free oxidation and electrolytic oxidation. The oxidation treatment of the spring is usually alkaline oxidation treatment, which is carried out in a caustic soda solution containing an oxidant (such as sodium nitrite, etc.). When the solution is close to the boiling point, the iron on the surface of the spring is dissolved, and sodium ferrite and sodium ferrite are generated, and then the magnetic iron oxide (Pe3O4) is generated by the interaction of sodium ferrite and sodium ferrite, that is, an oxide film with a thickness of approximately It is 0.5-1.5μm. The color of the oxide film depends on the type of spring material and the surface state of the spring, and is generally black, blue-black or tan. The springs made of carbon steel are darker, while the silico-manganese steel springs are brown.
Due to the beautiful color of the oxide film, greater elasticity and lubricity, no hydrogen embrittlement, low price and high production efficiency, it is widely used as a surface protective layer for springs. The corrosion resistance and wear resistance of the oxide film are lower than other chemical films. In order to improve the corrosion resistance and lubricity of the oxide film, phosphate treatment can be added after the oxidation treatment, or the spring after the oxidation treatment, and then soap liquid Impregnation and oiling