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.
