passiverende

Passiverende is the present participle of the Dutch verb passiveren and describes the action or process of passivation of a metal surface. It refers to creating a protective, adherent passive layer that reduces chemical reactivity and corrosion.

The passive film is typically an oxide layer that forms spontaneously when a metal is exposed to air or a suitable chemical environment. In stainless steel, the chromium-rich oxide layer (Cr2O3) acts as a barrier to ion diffusion, slowing corrosion and making the surface less reactive. The film is often self-healing: if small defects occur, the surrounding metal can reform the protective layer.

Passiverende treatments can be chemical, electrochemical, or thermal. Chemically, acids such as citric or nitric acid remove free iron and promote oxide formation. Electrochemical passivation uses controlled electrolytic potentials. Mechanical cleaning precedes passivation to remove scales and oils. Thermal passivation is used for some alloys by heating to promote oxide growth. The choice depends on alloy, environment, and intended use.

Used on stainless steels, aluminum, titanium, and other alloys to improve corrosion resistance in industries such as food processing, pharmaceuticals, medical implants, and chemical processing. It is often part of surface treatment protocols to prepare surfaces for coating or prolong service life.

The effectiveness of passiverende depends on environment; in high chloride environments or when the film is damaged, protective capabilities can be compromised. Standards and guidelines exist in the metal industries to document appropriate procedures and quality control, including guidelines for passivation of stainless steel.