Passivación

Passivación is a surface treatment process applied to metals, primarily stainless steel, to enhance their natural corrosion resistance. During passivation, the surface layer of the metal is chemically altered to remove free iron and other contaminants. This removal allows the chromium present in the alloy to form a thin, invisible, and highly adherent passive film of chromium oxide. This oxide layer acts as a barrier, preventing further chemical reactions and thus protecting the underlying metal from corrosion.

The process typically involves immersion in an acid solution, most commonly nitric acid or citric acid, at controlled temperatures and for specific durations. After the acid treatment, the metal is thoroughly rinsed to remove any residual acid and is then dried. Passivation is crucial for ensuring the longevity and performance of stainless steel components used in various industries, including medical, food processing, aerospace, and chemical manufacturing, where exposure to corrosive environments is common. It does not change the physical properties of the metal, such as strength or hardness, but significantly improves its resistance to rust and other forms of degradation.