Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ

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Hexavalent chromium in stainless steel passivation waters

Is it possible to generate hexavalent chromium in the process of passivating stainless steel (assuming a dichromate solution is not utilized within the nitric acid tank itself)?

Kevin Barrett
environmental protection - Hartford, CT, US
2004

From what I've been told, Nitric acid passivation (without other ingredients) should NOT result in heavy metals in the rinse water. The addition of HF (or Ammonium Bifluoride) will create a pickling solution and will result in metals in the rinse water.

If others have technical data to support or refute this, I'd be very eager to see it.

Todd Turner
- Monroe, Louisiana
2005

I have never heard of this happening and strongly suspect that it doesn't. Although nitric acid is indeed an oxidizing agent, hexavalent chromium is itself a powerful oxidizing agent, and I presume it cannot be created by simply exposing Cr⁰ or Cr⁺⁺⁺ to nitric acid.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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