Passivate Using Different Materials
Q. Can I passivate assembled parts with two different materials? One is 304 stainless steel tube and the other is 303 stainless steel solid. I am using epoxy glue made by 3M #2214 regular. I want to know if the acid will create problems to the glue or harm the parts. Thank you. T.K.
A. The answer will depend on your process. The most commonly used acid for passivating stainless steel is nitric acid, typically around 50%. This could cause a problem, in general, for epoxies. There will not be a problem with the 304 or 303 stainless steel parts, though. I would check to see if you can find any chemical compatibility charts for the 3M epoxy.
The other means for passivating stainless steel, although not as widely used, would be citric acid. The citric acid would not have any compatibility problems with the citric acid and, of course, would not be a problem for the stainless parts, either.
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