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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Porosity and corrosion of bright nickel plated components
Q. I WISH TO KNOW WHETHER IT IS POSSIBLE TO PRODUCE COMPONENTS IN BRIGHT NICKEL PLATING WITH ZERO POROSITY.WILL NICKEL PLATED COMPONENTS RUST DUE TO HIGH HUMIDITY OR NEARNESS TO SEA SHORE?.I WILL BE GRATEFUL FOR THE RESPONSES.
VENKIDUSAMYPLATING SHOP ENGINEER - COIMBATORE, TAMILNADU, INDIA
2007
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2007 A. Dear Mr Venkisamy,  Khozem Vahaanwala Saify Ind  Bengaluru, Karnataka, India  A. I don't know of a bright Ni plating solution that would have "zero porosity". If you want improved corrosion resistance sulfamate Ni, or better yet, electroless Ni would be the choice. The question is would it be bright enough for your customer's requirements? Most Ni plating suppliers would be able to plate up some samples for you. Good Luck! Mark BakerProcess Engineer - Syracuse, New York 2007 |
A. Porosity may come from several causes. Initial substrate porosity, induced porosity during preplate cycle, adhered gas bubbles, adhered dust or other particles, plate too thin. If all these causes are controlled, it is possible to plate w/o porosity. Multilayers are also used for increased corrosion resistance, where pores do not penetrate into the base material.
Guillermo MarrufoMonterrey, NL, Mexico
2007
A. Yes, I would use a bright nickel that has a leveler additive.
I prefer the bright nickel that has separate brightener additives. A. primary brightener,B. secondary brightener,C. leveling additive,D. Stress Reducer and E. wetting agent(anti-pit).
The more you plate(more time), the more leveling( closing of pores) and brightness(mirror bright) you get, the more stress in the plate & tendency to pit.
This conditions can be balanced and replenish by using a plating cell test( Hull Cell).
- New Jersey
2007
How to remove porosity in Ni Coating?
Q. How can we remove porosity from Ni electroplated coatings? The applied current density is 5 A/cm2 ^ A/dm2 and temperature is about 50 °C.
Could agitation of plating bath affect the properties of the coating?
- Isfahan, Iran
February 12, 2017
A. Hi cousin Ali. Is there a mistake in your units? Your current density sounds incredibly high.
Porosity will be highly dependent on thickness, and agitation is required to help remove gas bubbles.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 2017
Q. You are right. I made a mistake in the unit. The applied current density was 5 A/dm2. The substrate is plain steel and the thickness of coating according to calculation with Faraday's equation is about 50 microns. Electroplating time was 1 hour.
Another question: The prepared coating was opaque, however I found shiny Ni coating in other works. What is the problem? How can I prepare shiny coating?
Regards,
- Isfahan, Iran
February 13, 2017
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Hi again. 50 microns is quite thick, so porosity should not be a problem. But you probably need addition agents like surface tension reducers, carriers, and brighteners. If you can't get proprietaries, ASM Vol. 5, has a good chapter on generic addition agents for nickel plating if you can get access to a copy.
And if the shape of the parts and the production rate permits, you can manually buff the parts to brightness. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 2017
How to decrease porosity of Nickel (Ni) Coating?
Q. We have a coating of 8-12 micrometer coating over Brass. Electroplated Ni over Brass. What can be done to reduce the porosity of the Ni Layer.
Ajay PrasadStudent - Chennai, Tamil Nadu, India
June 23, 2017
A. Hi Ajay. Plate faster, use more agitation, use better brightener system, polish the brass, be sure the brass is fully clean and activated. More complicated would be to do a little electroless nickel before or after the electrolytic. But it would probably help if you gave us more facts & figures and less abstractness. Thanks.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 2017
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