Passivation

Passivation of stainless steel is a treatment with a mild oxidant intended to remove free iron and other foreign matter, for the purpose of improving corrosion resistance by enhancing the formation and structure of the material's naturally formed corrosion-resistant passive layer.

While not offering all of the benefits of electropolishing, chemical passivation will improve the corrosion resistance of stainless steel. The presence of exogenous surface contaminants may disrupt the formation of stainless steel's naturally corrosion-resistant surface layer. Surface contaminants, including grease, dirt, iron, and other metallic particles are inherent to the metal fabrication process. During a passivation treatment, the surface of a part is chemically treated by a mild oxidant. The chemical passivation treatment removes free iron and other foreign contaminants and promotes the formation of a chromium-rich corrosion resistant layer.

Harrison Electropolishing has performed stainless steel passivation treatments with excellent results since 1980. We have the capacity to passivate stainless steel components of all sizes at our facility or a jobsite anywhere in the world. Harrison Electropolishing will perform chemical passivation treatments in compliance with ASTM specifications or your industry or company specific chemical passivation standard.

Pickling vs. Passivation

Both pickling and passivation are intended to remove surface contaminants and improve the corrosion resistance of stainless steel. Pickling utilizes aggressive acids (usually a mixture of nitric and hydrofluoric acid) to dissolve heavy scale, weld oxides and other surface contaminants. Passivation solutions (citric or nitric acid) are not as aggressive and are not intended or are capable of dissolving heavy scale and surface oxides. Passivation is generally a cleaner and more controlled process, with parameters defined by ASTM standards. Thus pickling is used prior to or in lieu of passivation when the material has heavy contaminants or oxides.