Definition - What does Passivation mean?

Passivation is the process through which materials are protected from corrosion. Passivation aims to reduce the deterioration of materials (usually metals) caused by their reaction with the environment. The end goal of passivation is to increase the lifespan of the material in question by improving its corrosion-resistant properties.

Corrosionpedia explains Passivation

Passivation involves applying an outer layer to a material to protect it from harmful reactions such as corrosion reactions. The layer may occur spontaneously in nature through a process called self-passivating, or it can be introduced to the material as a micro-coating. In this case, a light coat of material, for instance a metal oxide is used to form a shield against corrosion. In microelectronics, passivation is useful in the enhancement of silicon. The great practical significance of passivation is that it protects structural metals from rapid corrosion that occurs in fresh water, moist atmosphere and aggressive chemical mediums.

In industry, the anticorrosive properties of a metal that result from its natural passive state can be supplemented through passivation where a suitable solvent is used to treat the metal. The action of the solvent takes place as a chemical or electrochemical process. Oxidizing agents are the common passivators although other substances may also be used for passivation. For instance, nitric acid is used to passivate aluminum ware and chromate solutions to passivate zinc coatings. The rate of corrosion is reduced by passivation depending on the type of metal and its environment.

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