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  for Metal Finishing since 1989
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How good is EIS?

I am trying to develop corrosion resistant organic coatings for steel substrates. I use EIS and salt fog test to evaluate performance of the coatings. Sometimes the results do not correlate, which one should I trust? I do not have a lot of time to go for field tests that go on for months. Is EIS a good indicator of corrosion performance? are there better techniques?

Karthik Suryanarayanan
Research Assistant - Cincinnati, Ohio
2004

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2004

Hi Karthik,

If the results of salt spray and EIS correlate with one another, then it is a coincidence. Salt spray testing correlates with nothing. When designed intelligently (and this doesn't happen often), it is a test whose results will give you information about relative performance of coatings or pretreatments.

There has been some research done to see whether EIS results will correlate with real-world corrosion behavior, but you will have to search the literature to see whether those experiments are relevant to your work.

George Gorecki
- Naperville, Illinois