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Passivation

  • Author:Memory
  • Source:www.xy-global.com
  • Release on :2017-11-29
PassivationIs to make the metal surface into a state of oxidation is not easy, but slow the rate of corrosion of metals. another kindActive metalOr alloy, in which chemical activity is greatly reduced, and the phenomenon of becoming a noble metal state, also known as passivation.

Passivation, metal Corrosion products generated by the action of the medium, if it has a dense structure, form a thin film (often invisible) that closely covers the surface of the metal and changes the surface state of the metal so that the metal electrode Potential greatly changes to the positive direction, and become a passive state of corrosion. Such as Fe → Fe ++ when the standard potential of -0.44V, after the transitional change to +0.5 ~ 1V, and shows the performance of the noble metal corrosion resistance, this film is called passive film.

Metal passivation may also be a spontaneous process (such as the surface of the metal to generate a layer of insoluble compounds, the oxide film). In the industry is the passivation agent (mainlyOxidationAgent) Passivation of the metal to form a protective film.

Common examples: cold concentrated sulfuric acid, cold concentrated nitric acid and iron, aluminum passivation can occur.