The oxidation treatment causes the spring surface to produce a dense protective film, so what are the spring oxidation treatment methods? Let Xiaobian tell you to sprout.
After oxidation treatment, the surface of the spring generation protection of magnetic iron oxide, this film is usually blue or black, sometimes dark brown. The chemical composition and the oxidation process, the surface state of spring material depends on the color of spring.
The methods of oxidation treatment include: salt oxidation, alkali free oxidation and electrolytic oxidation.
The alkaline oxidation method is the metal spring into a temperature about 140 DEG C, sodium hydroxide solution containing an oxidizing agent in the soaking time, oxidant and sodium hydroxide and iron, ferrous iron to generate acid sodium and sodium, and then react with each other, forming a magnetic iron oxide.
The oxidation film thickness is about 0.6~2um. film can improve the corrosion resistance of the metal spring, but because of thin film, and pores, so its protection ability can only be used for hardware spring work is not strong in the corrosive medium. The compact degree of its corrosion resistance depends on the oxide film and it the thickness, temperature and other factors of sodium hydroxide solution concentration, oxidant concentration, so it is decided by the oxidation treatment.
In order to improve the film corrosion protection and lubricating ability should strengthen oxidation treatment before and after treatment. Oxidation treatment should be thorough removal of spring surface rust, oxide skin, oil, heat treatment, surface contact salt slag layer. After oxidation treatment, it is usually filled in the metal spring or soap solution dichromate, then wash with warm water flow, dry or drying, oil processing and replacement of water film antirust oil or on the temperature of the machine oil.
Oxidation treatment has some erosion to the surface grain boundaries of some hot spring materials, which will reduce fatigue strength to some extent. Therefore, it should be careful in the process of oxidation.
Traditional oxidation treatment requires heating. In recent years, some domestic manufacturers use ambient temperature blackening agent, which overcomes the defects of traditional blackening process and saves a great deal of energy.
Blackening agent is blue green, concentrated liquefaction, no impurities, no peculiar smell, no burning, no explosion, no corrosion, transportation safety. Diluted with diluted agent, diluted when spring is used, the dilution ratio is about 1:5.
The operation process of blackening agent is simple, the process route is: degreasing, rinsing, acid, rinsing, black (2~5min at room temperature), rinse water displacement antirust oil. It should be noted that: must put the workpiece on the special-shaped spring oil to do, after cleaning, can put in the agent in normal temperature oxidation treatment.