What is passivation?
Passivation treatment: The process of forming a trivalent or hexavalent chromated layer on the surface with a chromate solution and metal, known as passivation, also known as chromizing.
The chemical activity of different metals varies greatly. Active metals are highly susceptible to corrosion in environmental media, while non-reactive metals exhibit good corrosion resistance. However, some of the more active metals are supposed to be corrosive in some environments, but they are unusually corrosion-resistant. If the electrode potential of aluminum is much higher than that of hydrogen, it should be rapidly corroded in aqueous solution. However, aluminum is resistant to corrosion by water and humid atmosphere. Because aluminum is easily passivated by oxygen in the air, it is widely used as cutlery and building decoration materials.
The passivation mechanism can be mainly explained by thin film theory. It is considered that the passivation is due to the interaction of the metal with the oxidizing medium, and a very thin, dense, well-covering, and strong covering metal can be formed on the metal surface. Passivation film on the surface. This layer of film exists as a separate phase, usually oxygen and metal compounds. It plays a role in completely separating the metal from the corrosive medium, preventing the metal from directly contacting the corrosive medium, so that the metal basically stops dissolving to form a passivation state to prevent corrosion.