Hand board surface treatment process ②: Passivation

We know that metal products are easy to be corroded. In order to prolong the service life of metal products and improve the anti-corrosion ability of metal products, passivation protection must be carried out. Our common metal objects such as ships and cars are passivated.

Passivation is a method to change the metal surface into a state that is not easy to be oxidized and delay the corrosion rate of metal. In addition, an active metal or alloy, in which the chemical activity is greatly reduced and becomes a precious metal state, also known as passivation. If the corrosion products produced by the metal due to the action of the medium have a dense structure, form a thin film (often invisible) and closely cover the surface of the metal, it will change the surface state of the metal and become a passive state of corrosion resistance.

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

Compared with other surface treatment processes, passivation treatment has the following advantages:

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

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

3) Passivation promotes the formation of oxygen molecular structure passivation film on the metal surface. The film is dense and stable, and can repair itself in the air at the same time. Therefore, compared with the traditional method of coating antirust oil, the passivation film formed by passivation is more stable and corrosion resistant.