Chemical passivation
The targeted formation of a thin, oxidic protective layer on metallic surfaces using oxidizing reagents. This increases corrosion resistance by suppressing localized galvanic cells.
Passivation means that a protective oxide layer forms on the surface. This happens automatically when the material is clean and comes into contact with oxygen. In welding, this is important because otherwise the weld seam and heat-affected zone are susceptible to corrosion – especially with stainless steels. If you grind or brush after welding, you destroy the passivation layer. Then you have to treat the area again, for example with a pickling agent or passivation spray. It is important that the surface is grease-free and clean before applying the agent. The exposure time and temperature depend on the manufacturer's instructions, there are no general values.