In surface technology, the term passivation is used when a protective layer is created on a metallic material. Passivation increases the resistance of the surface to corrosion through a chemical reaction in the passivating acid. The protective layer created in this way is intended to prevent or significantly slow down the corrosion of the base material.

During pickling, a thin metallic layer is removed from the steel surface. A mixture of acids is used for this. The aim is to remove annealing colours or light scaling (e.g. after heat treatment).

The surface of stainless steels usually passivates automatically, but it is often necessary to follow the pickling process with a passivation process. Passivation takes place by means of an oxidising acid treatment. No material is removed during this process, but the composition and thickness of the passive layer are specifically optimised. Whether and how quickly metals corrode depends on their material properties. It plays a decisive role whether the metals themselves can generate spontaneous passivation and whether they can be provided with a protective layer using a passivation process.

Arguments

• Even complex geometries possible
• Increased corrosion resistance
• Single part and series production