- Feb 06, 2018 -
Passivation is the process of transforming the metal surface into a state that is not easily oxidized, and delaying the corrosion rate of the metal.
Corrosion is a process of electrochemical change, the untreated metal surface there is a small amount of electrical ions, these ions from the high potential region (cathode) to the low potential region (anode) movement, thus generating electricity. Under the action of this electric current will accelerate the destructive attack on metal and corrosion in the spot where the metal potential is weak, rust is popular.
The mechanism of passivation can be explained by the theory of thin film, that is, the passivation is due to the role of metal and oxidizing substances, the role of the metal on the surface of a very thin, dense, good coverage performance, firmly adsorbed on the metal surface of the passivation film. This layer of film is a separate phase, usually a compound of oxidized metal. It plays a role in separating the metal from the corrosive medium and prevents the metal from contacting the corrosive medium, thus making the metal basically stop dissolving to form a blunt state to prevent corrosion.