Trivalent Chromate Treatment

[BirdmanofVT]

I am a mechanical design engineer conducting a thorough investigation of whether NavAir trivalent chromate pre-treatment/post-treatment meets the requirements for a military application. I have found a bunch of great test data, but nothing that tells me that the treatment meets the requirements after exposure to extremely cold temperature (-125 F). They tested this treatment on aircraft, and aircraft see similar temperatures, but I can't find anything that confirms that low temperature exposure isn't a problem. I imagine that its fine, but guessing is not an option, and at this point in the design process I can't do all of the testing that would be required. Is there any resource, ie. literature, that will help me understand from a materials engineering point of view that I should not have a concern for this?

 

[Goahead]

The base metal onto which the treatment is applied is not specified in your presentation.
The purpose of the application (corrosion protection, base for paint etc.) is not explained.
The process operating conditions and the thickness of the coating are not clarified.
The requirements after exposure to cold temperature are not established.
It seems that more information would be helpful.

http://www.welding-advisers.com/

 

[BirdmanofVT]

Thanks for the response, Goahead. The base metals are aluminum 6061-T6 and 7075-T6. The purpose is corrosion protection and paint base, except paint will be omitted at faying joints where conductivity is required for ESD. You say the process operating condition, but do you mean system operating condition? The system operating condition is a military application, with the driving requirement for corrosion prevention being a 24 hour salt fog test. The process operating condition will be per the procedure that I assume is referenced in the NAV-AIR licensing agreement that the finisher is required to comply to. I don't know what thickness I would need to call out, I haven't gotten that far yet, but the thickness would be such that the coating meets the NAV-AIR licensing agreement, MIL-C-5541, and MIL-DTL-81706 for my materials. The system has to meet all performance requirements after exposure to the cold temperature, including the salt fog. I think that any cold weather performance data for TCP would have been specimens that had TCP applied per the NAV-AIR licensing agreement, 5541, and 81706, otherwise I think it would be pretty useless data.