Impact of Heat on Chromate Conversion Coating


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Q. We build military radios and are considering powder coating CARC paint on our radios. We use trivalent chromate conversion coatings on all surfaces prior to painting. Will the internal trivalent chromate conversion coatings that are not protected by the CARC paint degrade and become less non-conductive or resistant to corrosion?—J.F. 
A. The chromate conversion coating has moisture content that is sensitive to temperature. If it is exposed to temperatures above 140°F for enough time, it will dehydrate and lose a significant degree of corrosion and electrical resistance. The material may not totally lose the desired properties, but it will be compromised. I suggest you do some testing to see if it is a major problem for your parts. Subject the exposed chromate to the oven on your line and then do some corrosion and resistance testing to see if the surface is acceptable for your operation and specifications.

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