Why is it Important to Passivate after Electropolishing?

 

Although, Electropolishing can be considered a passivation process, it is only as good as using phosphoric acid. With phosphoric acid typically we see chrome to iron ratios in the range of 1.2 to as high as 1.4, It does not meet the passivation requirement of nitric acid at 1.5 and certainly not as high as passivating with citric acid. Passivating with citric acid after Electropolishing could yield a range of 1.8 to as high as 2.0 thereby achieving a highly corrision-resistant surface. 

It's very important to passivate the surface after electropolishing in order to improve the passive film at the highest levels!  It is best to have a fully passivated, highly corrosion-resistant surface.

Watch the Video Below to hear Daryl Roll's explanation: 

 

Before and After EP Photo! 

10 HP chemical tanks before & after EP.jpg

 

Additional Resources:

Insights into Electropolishing & Mechanical Polishing Presentation 

Electropolishing Brochure

Comparing Passivated & EP'd 316L SS Surfaces

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