Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Zinc plating on copper
Q. I am plating Cu plated parts in caustic base alkaline zinc plating bath but after plating bubbles are observed.
M.S. parts are not showing any problems.
- Nashik,Maharashtra, India
December 3, 2024
A. Hi Avinash,
I assume the copper plated parts are also made of steel? (If they are zinc discastings it would probably be related to the copper not being thick enough to prevent the caustic from attacking the zinc).
Assuming the parts are steel, the copper plating on them is apparently not a suitable base for alkaline zinc plating due to excess brighteners or other contamination on the surface. Are you doing the copper plating in house -- if so, can you tell us about it (cyanide, pyro, or bright acid copper), etc.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. I get Copper plated parts from my customer.Hence I don't know the Cu plating process but I am facing the problem.
Will Sulfuric dip is more correct than HCl as I am using HCl dip after degreasing & anodic cleaning ?
- Nashik, Maharashtra, India
A. Hi again,
I think you are on the right track. The HCl is too aggressive for copper plating. The anodic electrocleaning may be as well.
Perhaps you should try scrubbing a few sample parts with a pumice solution and rinsing them, and just completely skipping your cleaning cycle to see how that works.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. So, shouldn't use Sulfuric acid dip also?
Avinash Vidhate [returning]- Nashik, Maharashtra, India
December 12, 2024
A. Hi Avinash,
I don't think it's necessary but it seems highly unlikely to hurt if it's available.
What I was trying to convey, was the idea of separating your cleaning cycle from your plating cycle for testing purposes so you can determine if the plating will work properly once the cleaning has been sorted.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Dear Ted,
Thanks for your suggestion,
And I shall do as you have suggested.
- Nashik, Maharashtra, India
December 12, 2024
⇩ Related postings, oldest first ⇩
Q. Can zinc plating be done on copper. We have a requirement of copper tubes which should be zinc plated? Sounds strange can you help me in deciding the correct processing parameters?
Satish Deshpande- Mumbai, Maharashtra, India
2002
by N. Kanani
on AbeBooks or
eBay or
Amazon
(affil links)
A. Why not? If you don't require internal plating, it would be a good idea to plug up the ends with rubber to prevent dissolution of the copper in whatever type of plating solution you use.
Regards,
Khozem Vahaanwala
Saify Ind
Bengaluru, Karnataka, India
A. Technically, zinc plating on copper is not a problem. However, diffusion of the zinc into the copper will occur. If the zinc plating is not of sufficient thickness it may seem to disappear! Obviously, the resultant material at the interface of the zinc and copper and after migration will be brass. The big question is why do they want zinc?
Gene Packmanprocess supplier - Great Neck, New York
Q. What if I wanted to put trivalent chromate over the Zn plated copper? We have a copper plated pin that gets brazed into another part. The assembly then gets Zinc + chromate for corrosion resistance. The copper seems to be reducing the effectiveness of the chromate and we get white dust (Zn oxide?) and some red rust when we salt spray test.
Grant
- Westfield, Indiana, USA
February 28, 2011
A. Hi, Grant.
It is true that the galvanic couple between zinc and copper is stronger than between zinc and steel, so that once the copper is exposed the zinc will corrode faster. But perhaps a heavier layer of zinc, such that there is no porosity, will solve the problem. It sounds possible that most of the zinc plating is going onto the steel, and very little onto the copper; please measure the thickness of the zinc on the copper.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 2, 2011
Why does zinc plating of copper soften the copper?
Q. I want to ask about Zinc electroplating of Copper, using ZnSO4, and H2SO4 as additive agents. Why did copper hardness after electroplating drop? Before this experiment, the hardness reading was 20 above. Anyone can help?
hiroqas piya- Kangar, Perlis, Malaysia
September 20, 2015
A. I seriously doubt if the zinc plating softened the copper. I think that the hardness testing is the problem. The zinc is very probably softer than the parent copper and you are reading a value of both.
If in doubt, sand the zinc off of a part and take another reading of the copper. On the same part as the before plating.
- Navarre, Florida
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