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Iron in Passivation Bath

In a Nitric 2 passivation bath (as defined by ASTM A967) Type VI passivation bath (as defined by QQ-P-35C (canceled) [link is to free spec at Defense Logistics Agency, dla.mil]) what should the iron ppm be, and at what point should the bath be dumped?

Katherine Carr
Plating Shop - Lilburn, GA, USA
2004

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2004

Katherine,

As indicated in the ASTM A380 paragraph A2.6 the iron content should not exceed 2 weight %. this is about a 2 pound piece of dissolved iron in a 15 gal tank. I know this sounds like a lot of iron but it is the acceptable maximum limit as outlined by ASTM. In ppm terms that is 20000 ppm of allowable iron. I have asked this same question earlier and have been suggested 1 weight %. This is the limit we have adopted in order to keep better control over the baths. If by chance you have knowledge of an iron measuring instrument please let me know. Thanks and good luck.

Kevin Dodd
Medical device manufacture - Texas

How about a buret as a "iron measuring instrument". Nothing like a good old fashioned titration. Or you can do a colorimetric. There are probably "test kits" available. (Hach or others)

Douglas A. Hahn
- Rocky Mount, North Carolina
2004

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Does anyone know where to purchase a iron content test kit that can be used to verify the nitric acid passivation bath per AMS2700B has less than 2% iron?

Steve Mosychuk
- Jacksonville, Florida
March 7, 2008