Acid Passivation of Stainless-Steel Parts


Stainless steel is a steel alloy containing at least 11% chromium. It is well-known for its corrosion resistance properties which derive from its chromium content. The chromium, in the presence of air (oxygen), forms an inert layer of chromium oxide that covers the surface of the stainless steel and makes it less likely to react with air and cause corrosion. Ideally, a thick oxide layer is formed completely when the pure, cleaned stainless steel is exposed to oxygen. Contaminants need to be removed in order to improve the corrosion resistance properties by a process known as passivation.

The passivation process takes place in a passivation chamber, where the metal parts are treated with different liquids in a series of steps. The first step is always cleaning. Cleaning is done with a detergent specifically chosen depending on the contaminants.

In-line concentration measurement of the acid bath with the Vaisala K-PATENTS® Teflon Body Refractometer is a safe, reliable and quick method to monitor that the passivation is performed at all times within the recipe specifications.

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Acid Passivation Process

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