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Ted Mooney, P.E. RET
Pine Beach, NJ
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Nickel plated parts peel when powder coated
Q. I have an adhesion issue with powder coating on nickel plated bearing-type parts. Both nickel and powder peel-off is observed during the process. Rejection observed 5% for adhesion issue. Please give the solution to avoid rejection.
Amit KadamEngineer - Pune, India
May 23, 2022
A. Hi Amit. I strongly doubt that the chemistry plays any part is this. When nickel plating adhesion is marginal, it will peel when heated. I suggest that you put a few nickel plated parts into your oven without any powder on them and look for blistering. Once you know what happens we can move on to the next step.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
May 2022
May 24, 2022
A. Hello, Amit,
I work with door locks and I used to powder coat parts that would be rejected when there were spots/burns in my nickel coat.
What I observed is that nickel isn't a very good base for powder coating, since the powder coat sometimes would peel off (not always).
However, in your case, you're saying that it's the nickel that peels off, therefore I think that the problem here isn't the powder coating, but the nickel itself.
I do an adhesion test where I smash the parts with a hammer to see if the nickel peels off. If it does, it usually means -in my process- that the activation step before the nickel didn't work properly. Excessive additives in the nickel bath could also cause this.
I also agree with Ted, you should test the parts before powder coating to check for the peeling/blisters.
Regards,
Chemical Engineer - Nova Friburgo, Rio de Janeiro, Brazil
Q. I had conducted heat quench test at 200 °C for 2hours but no peel-off observed.
Amit Kadam [returning]Engineer - Pune, India
May 24, 2022
A. Hi Amit. I won't insist that I'm right and the problem is heat rather than chemical reaction, but I will say that my guess remains that it's heat not chemical reaction, or someone thinking the nickel is coming off when it isn't ... because I've never heard of plastic powder reacting with nickel plating and I can't picture it :-)
What happens to the parts after they are plated and before the powder is sprayed on them please?
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
May 2022
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