Metal finishing Q&As since 1989
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Ni/Zn Passivate adhesion post Ni/Zn plate
Q. We paint parts that have been treated with Zi/Ni AMS2417 type 2, but sometimes we have adhesion problems on some of the parts in the batch.
Wet paint system is according to MIL-PRF-23377
[on DLA] type 1 and MIL-PRF-85285 [link is to free spec spec at Defense Logistics Agency, dla.mil]
, when we test the paint at aluminum test panels treated with MIL-DTL-5541 we do see any problems.
Is there something in the Zi/Ni process that can improve the adhesion of the paint, and the other way around is there something in the process that have a negative impact to the adhesion.
We degrease the pars before we paint them, and do the "water on goose test".
- Denmark Vildbjerg
January 19, 2022
⇩ Related postings, oldest first ⇩
Q. We have been using a Zinc-Nickel plate tank for sometime now using the E-Bright solutions provided by EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser]. We are also using the post chromate treatment (Ni/Zn Passivate). Well we had been using that post chromate at an ambient temperature and then Boeing came in and said that it had to be at 100 °F ± 5 °F per BAC 5637. Since raising the temp to 100 °F, we have had nothing but adhesion problems which were not there prior to raising the temp. The manufacturer recommends 70-85 °F. Has anybody else out there had any situations like this? Can you offer any advice or suggestions?
I would appreciate any help.
Tony Schmaltz- Kent, Washington
2002
A. Tony,
Bath temperatures above 90 °F cause a loose deposit according to the following reference. Jack Kinder, "Chromate Conversion Coatings" American Electroplates' Society, Inc., 1986.
Best Wishes,
Mary Cera- OKC, Oklahoma
2002
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