Why metal parts need make passivation?

We all know that metal products are easily corroded.

 In order to prolong the life of metal products and improve the corrosion resistance of metal products, they must be protected by passivation. Our common metal objects such as ships and automobiles are all passivated.

Passivation is a method to transform the metal surface into a state that is not easily oxidized, and to delay the corrosion rate of the metal. In addition, the phenomenon of an active metal or alloy in which the chemical activity is greatly reduced and becomes a noble metal state is also called passivation. If the corrosion product generated by the metal due to the action of the medium has a dense structure, forming a thin film (often invisible) that tightly covers the surface of the metal, it will change the surface state of the metal and become a corrosion-resistant passive state.

Passivation treatment is the last process step in chemical cleaning, which is a key step, and its purpose is to prevent corrosion of materials. For example, after the boiler is pickled, washed with water, and rinsed, the metal surface is very clean, very activated, and easily corroded. Therefore, passivation treatment must be carried out immediately to form a protective film on the cleaned metal surface to slow down corrosion.

Passivation Advantages

(1)Compared with the traditional physical sealing method, the passivation treatment has the characteristics of absolutely not increasing the thickness of the workpiece and changing the color, improving the precision and added value of the product, and making the operation more convenient;

2) Since the passivation process is carried out in a non-reactive state, the passivation agent can be added repeatedly, so the service life is longer and the cost is more economical.

3) Passivation promotes the formation of an oxygen molecular structure passivation film on the metal surface, which is compact and stable in performance, and has a self-repairing effect in the air at the same time. Therefore, compared with the traditional method of applying anti-rust oil, the passivation film formed by passivation is more stable and more corrosion-resistant.