Definition - What does Passivate mean?

Passivate, as related to engineering and physical chemistry, refers to treating materials so they can withstand adverse environmental conditions or are less affected by air, water, chemical reactions or acidic reactions. Passivation shields the outer layer of the base metallic material from corrosion.

Corrosionpedia explains Passivate

In the passivation process, the base of the metallic material is coated with a protective material such as metal oxide, which helps to create a shell against the corrosion. A very light coat of metal oxide is applied on the base of the metal.

If a passivation process is not performed on any metallic surface, then when exposed to harsh environments, the metal naturally becomes hardened and rough and the outer coating starts peeling. As the coating is peeled off, the surface is exposed to chemical reactions and corrosion slowly eats away the material from the inside, which promotes further loosening of the coating in the nearby surface area. However, if the passivation process is performed then peeling of the outer coating is not a threat. Silicon, aluminum or zinc oxides are used to passivate the metallic surface. Stainless steel can also be used because it is naturally corrosion resistant.

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