Passivation is one of the benefits of electropolishing. However, passivation can also be obtained through a chemical process, such as the traditional Nitric Acid passivation process. This chemical process doesn’t employ electrical current or require specialized racking, and thus doesn’t alter the visual appearance or surface finish (Ra, RMS) of stainless steel.
The traditional Nitric Acid passivation process removes surface contaminants and facilitates the formation of a very thin, transparent oxide film, which protects the stainless steel from oxidation.
Passivation through Electropolishing
NEE believes that a mild electropolishing cycle is the most effective means of passivation. Electropolishing will meet or exceed all traditional passivation requirements for corrosion resistance as well as provide a number of benefits:
- The electropolishing process removes all free iron from the surface of the work piece, which has the obvious effect of eliminating free iron corrosion up front.
- Unlike Nitric passivation, a mild electropolishing cycle removes a small amount of surface material including additional free iron beneath the surface of a part.
- Electropolishing increases the chromium oxide layer to a greater degree than traditional passivation methods, thus enhancing the part’s corrosion resistance.
- Due to its increased corrosion resistance benefits, NEE generally recommends passivation through mild electropolishing. However select situations don’t lend themselves to this surface treatment method.
To discuss whether the traditional Nitric Acid passivation process is suited to your parts and application, please call Luke Almeida at 800-672-6616 or complete our brief inquiry form.
Our process is compliant with ASTM A967, “Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts.”