30 March 2015

Stainless steel passivation

What is passivation? How is it conducted and what for? Let’s take a closer look in the features of this procedure. 

First a few words on what this procedure is. Passivation is a metal treatment procedure that makes stainless steel more corrosion resistant. A thin, protective layer with the product’s own consistence is created during passivation on its superficies. It is very common that after the processing of the metal, non-visible scraps and dust get stuck on the top coat of the final product and turn the metal less resistant to corrosion. In order to remove the debris from the surface we conduct the “pickling” procedure and to enhance the consistence of the metal’s surface we use “passivation”.  

PICKLING:
To prepare the product properly for the passivation we need to pickle it. This means to remove the remains from its surface with the special chemical fluids (usually nitric and hydrofluoric acid). The metal is dipped into the pickling “bath” for as long as it is scheduled.

PASSIVATION:
Stainless steel passivation not only augments the superficial resistance to corrosion but also extends its life expectancy and gives the product a more shinny, polished finishing and look. Stainless steel is a highly corrosion-resistant alloy and with the passivation procedure is to reinforce the top coat to the maximum. Oxygen is absorbed and a layer of monocular oxide is created on the surface. This way the chances of corrosion penetration are reduced to the minimum level.
Passivation and pickling are conducted in “baths”, special bath-tabs where the material is dipped into and by staying in the chemical solutions (the one that is appropriate each time) it acquires the features mentioned above.
After the passivation we run several tests in order to assure its success; testing materials like salt-based liquids get applied on the product that also gets exposed to high humidity levels.  
If the metal stays intact we have successfully completed the pickling and passivation procedures.

Last but not least it is worth to mention that passivation is a very delicate procedure during which, if the steps are not followed properly, the product could be ruined and we could provoke the exact opposite results then the ones we were going after.