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Q&As since 1989
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Aluminium oxide removal before plating on aluminum
Q. I want to remove aluminium oxide layer from aluminium before electroplating in cyanide solution. What should I do? Is aluminium oxide soluble in cyanide solutions at pH 9-11?
taher rmember - Iran
July 1, 2008
A. Hi, taher. No, you don't copper plate directly on aluminum. Do we understand that you are not applying zincate or any other prep layer before trying to cyanide plate the article?
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
July 1, 2008
Q. Hi
Thanks for your answer.
Let me tell you that I hadn't applied zincate coating.
Should I apply it?
I want to apply indium coating from cyanide or sulfamate bath after aluminium surface treatment; what kind of surface treatment should I do for aluminium?
taher - Iran
July 3, 2008
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A. Hi again. In general, to electroplate onto aluminum you must start with a zincate layer. That is because aluminum oxidizes instantly, and electroplating must be done on a metallic surface not a metal oxide surface. After the zincate, either alkaline copper or alkaline electroless nickel are the usual next step, followed by whatever you wish as your final plating. You can find more about zincating from most plating texts or just by searching for that term with our search engine. Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
July 6, 2008
Q. Hi
I have some questions about zincating and it's benefits:
1: Can zincating destroy the aluminium oxide which has been formed on it?
2: Is it necessary to zincate before indium plating on aluminium?
3: Can zincating increase aluminium sacrificial anode's efficiency at cathodic protection by inhibition or destroying the aluminium oxide?
student - Tehran, Iran
July 4, 2008
A. Hi Taher.
1. Zincating is intended to be used after etching and desmutting, to displace the small amount of oxidation which forms on aluminum immediately; it is not a substitute for other pretreatment steps.
2. Yes, it is necessary to do a chemical displacement operation like zincating before plating on aluminum; but there may be other similar displacement reactions such as mixed zinc & nickel, or tin-based displacement processes. Zincating is by far the most common.
3. Sorry, I don't know if it's practical to make aluminum sacrificial anodes work better by zincating them; I tend to doubt it since the zinc completely covers the surface.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 2016
Indium Plating on Aluminum
Q. Question: I would like to plate two aluminum surfaces with indium, roughly 1.00 wide x 10.00 long. Parts will be clamped together.
Goal is to reduce the thermal contact resistance between parts. Cannot use foil due to frequent removal and installation of aluminum parts.
Any information appreciated.
lsi engineering - tewksbury, Massachusetts, USA
January 26, 2016
A. Hi Len. I have no experience with that, but suspect that it is doable and practical via zincating, followed by electroless nickel plating, followed by indium sulfamate plating.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 2016
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