The Concept And Precautions Of Passivation Treatment

–  Concept

Passivation process is oxidized the metal by strong oxidant or electrochemical method to make the surface inactive. It is a method to transform the metal surface into a state that is not easy to be oxidized and delay the corrosion rate of the metal. In addition, the phenomenon that an active metal or alloy becomes a noble metal with its chemical activity greatly reduced is also called passivation.

After passivation, it can be formed a very thin, dense and good-covering oxide metal compound, it is the passivation film. This passivation film can be firmly adsorbed on the metal surface, to completely separate the metal from the corrosive medium and prevent the metal from contacting the corrosive medium, so that the metal basically stops dissolving and forms a passive state, to achieve the effect of anti-corrosion.

–  Precautions

1. Do pretreatment before passivation. It is needed to do mechanical cleaning to remove the clear dirt on the surface. For some stubborn stains, it needs to usespecial cleaning agents and chemical treatment methods, to dissolve the dirt. To ensure the formed passivation film will be completed.
2. Try not to use metal wire brushes or grinding wheels or wire brushes on metal surfaces, but use carbides or other non-metallic substances.
3. If the product needs to be finished with heat treatment, complete cleanliness is essential. This is because stress relief, annealing, stretching or other heat treatment processes can actually deeply attract external contaminants into the matrix, making it hardly removed during the passivation process. In addition, the heat treatment should mainly prevent the formation of oxides.
4. After completing the operations, it can be proceeded passivation. It needs to control the ratio and follow the normal operation of passivation. After passivation completion, it has to be proceeded quality inspection.