Method for the thermochemical passivation of stainless steel
AssigneePoligrat GmbH
InventorsOlaf Bohme, Siegfried Piesslinger-Schweiger
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Abstract
The present invention relates to a process for improving the heat and corrosion resistance of stainless steel by means of a novel passivation process. This process comprises a chemical treatment with an aqueous solution comprising a complexing agent combination of at least one oxidant, a subsequent rinsing and a subsequent treatment at elevated temperature in an oxygen-containing atmosphere. The stainless steel surfaces obtained according to the invention have a homogeneous passive layer having increased chemical resistance and resistance to thermal discoloration.
Claims19
A process for the passivation of stainless steel, wherein the stainless steel is subjected
- firstly to a chemical treatment with an aqueous solution containing at least one polydentate complexing agent for iron and at least one oxidant, where the oxidant is able to ensure a standard potential of at least +300 mV in the solution,
- subsequently to a rinsing step with water and
- then to a heat treatment at a temperature of at least 80° C. in an oxygen-containing atmosphere.
(canceled)
Dependencies are inferred from the claim text.