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MIL-DTL-5541 Chem film fails humidity test

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Tutorial:
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MIL-DTL-5541 [affil. link or DLA] specifies a chromate conversion coating for aluminum. In the USA, the slang "chem film" is often used as a synonym. Two proprietary trade names for the process, "Alodine" and "Iridite" are so common that people often use them generically to refer to the process.

Q. Have a finishing problem on a following material after 10 day 95% humidity test.

Material: .090 thk. AL ALLOY 5052 H32 PER AMSQQA250 [affil. link]
Finish: Chem film per MIL-DTL-5541 [affil. link or DLA] TYPE II (Trivalent Chromium) CLASS 3 Color Clear.

My question is why the finishing is not holding up, or do I need to use harder finish like Anodize

Help !!

Onder Onal
- Ronkonkoma New York
December 29, 2022


A. Hi Onder.
MIL-DTL-5541 [affil. link or DLA] requires 168 hours of ASTM B117 [affil. link] salt spray testing and specifies how to determine whether the sample passed or failed. You are doing a 10-day humidity test instead of the 7-day salt spray test, and my guess is that that they should pass, but what is your pass/fail criteria since MIL-DTL-5541 [affil. link or DLA] is silent on that?

There is a lot you haven't told us yet, like whether this is a new problem or a long-running one, whether it affects all parts or just a particular part, whether it affects all of that style part or just a small percentage, and whether you are doing the processing in house or buying the processing service. If you are buying the finishing service, have you considered the possibility that the parts were missed and not chem-filmed? What test or evidence do you have that they were processed per the spec? Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey





Closely related historical posts, oldest first ...

Finish for 5052-H32 Aluminum

"Surface Properties of Conversion Coated Aluminum"
by Raj & Ali
from Abe Books
or

Affil. Link
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Q. I have a 5052-H32 Aluminum enclosure used in an indoor cabinet. The finish should be corrosion resistant, conductive and cost effective. What kind of finish should I choose?

Cedar Li
- Orlando, Florida, USA
2001


A. Chromate conversion coat.

Tino [last name deleted]
consulting - Montreal, Canada


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