The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Electropolishing VS. Nitric/Citric Passivation

I was wondering if there have been any studies done that compare and contrast Electropolishing VS. Nitric/Citric Passivation?

Chadwick J. Murray
- Bradford, PA U.S.A
2002

---

2002

Chadwick:

Yes, there have been a number of studies. Although electropolishing takes on an entirely different method, it will improve the corrosion resistance dramatically because it eliminates the high points where electrical contact can be made to produce corrosion. There are some other theories about this, in how electropolishing affects the intergranular boundaries.

We have a Report from NMI Research in Europe funded by the Surgical Industry in Europe. This large test program compares unpassivated samples with nitric acid passivation, CitriSurf passivation, electropolishing and another sequestering agent system from Europe. This report is available from us, or from NMI in Europe in German. This was a TOTALLY INDEPENDENT study run by NMI at the University there and shows that the citric acid system is the best. We could post this report if Finishing.com would like it.

We have found that the absolute BEST system for producing the best corrosion resistance and chrome oxide layer on the surface is a combination of electropolishing + passivation with our citric acid formulations. This is from data from our customers. We have also learned that the amount of chrome oxide and subsequent corrosion resistance depends in a LARGE degree on pretreatment and rinsing procedures, depending on the grade of stainless. We are willing to share this information, and will be presenting it in a number of public forums in the near future.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois