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topic 425

Nickel plating of tungsten carbide


(1996)

Q. We manufacture small, precision tungsten carbide parts on a subcontracting basis. We have a long-term order to supply large quantities of electrolytic nickel -plated tungsten carbide pellets. We are looking for a plating company to provide this service, or alternatively, to purchase a small plating line for in-house production (because of the large volume and unique application). The following is a description of the part to be coated: Material: 10% cobalt-binder tungsten carbide. Dimension: 1.32 OD x 2.1 mm (0.052" OD x .083" long) The edges are slightly rounded.
Unit Weight: 0.043 gram (0.0015 oz) each. Quantity: About 2-3 million parts per month Coating: 3 to 7 micron thickness. The coating is intended to facilitate joining the pellets to a steel strip in a resistance-welding process performed in an argon environment.
The parts must go through a post-coating embrittlement relief process to improve adhesion quality. To test the adhesion quality, the parts are heated to 800 C in a vacuum furnace and are then examined under a microscope to see whether entrapped bubbles have emerged from a void between the coating and the carbide. Such a part is considered unsatisfactory.
Our results to date with local suppliers have not been satisfactory. We still have the bubbling problem and less-than-desirable adhesion quality. Thus we are looking for new alternative solutions. We would appreciate if you could help us with experience you may have with such an application. Can you offer coating services, or preferably, could you design and provide us with a small coating line? Do you think our problem may be due to preplating preparation of the parts? Can you provide us insight into your recommendations for solving this problem? If you would like to work with us on this project, we would be happy to send you samples for testing. If you cannot, we would appreciate if you could provide us with the name of someone in the industry that might be interested.

Ethan Matlaw
microtools - Israel
outdated


(1996)

A. I got involved in plating on tungsten carbide a few years ago on missile parts, we found that a high chloride nickel strike (woods) after anodic sulphuric etching gave satisfactory adhesion, although we were plating with 0.0003"- 0.0005" ENP rather than electrolytic nickel.

Regards

Richard Guise
- Lowestoft, U.K.


(1996)

A. We have successfully nickel plated tungsten carbide inserts that were subsequently brazed onto machine tools. And we have successfully nickel plated small cobalt pellets used in x-ray machines. We have not, however, plated small tungsten carbide parts as you describe.

Kent

Kent Backus
Fort Worth, Texas, USA


(2001)

Q. I've spent many a late night researching plating on your site and can say confidently that it is the most informative and liberal source of information I have found. I read that many others feel the same and I thank you for the time you selflessly dedicate to the requests of others.

I have one question for you and it does not include a plea for process or constituent. Is it possible in your experience to copper or nickel plate tungsten carbide?

I thank you for your time.

Dean T [last name deleted for privacy by Editor]
- Sydney, NSW, Australia


(2001)

A. Thanks so much for the kind words, Dean, they are really appreciated. But 'selfless' is way too strong -- this is my job, and although the posters don't pay for the postings, we get revenue to run the site from our supporting advertisers :-)

Tungsten and other refractory metals can be plated, but only with substantial difficulty. Volume 5: Surface Engineering of ASM's Metals Handbook offers the methods.

I recognize that you actually asked about tungsten carbide. Transactions, vol. 66, page 144 (1988) has an article on "Nickel Electroplating onto Tungsten Carbide Powder", and the Shop Problems column in the July 1980 issue of Metal Finishing magazine describes an expired patent on anodic treatment at 1-5 ASI, 68-140 °F, 100-250 g/L sodium pyrophosphate to etch the surface before rinsing and nickel plating.

And we combined your posting with another thread on the subject which suggests that a Wood's nickel strike following anodic sulphuric acid etching can work.

Caution: Be very careful in attempting to apply any technology to plating onto powder (if that is your situation); the huge surface areas can make the processes very active--even explosive. Just as powdered metal can explode in air because of the high surface area, it can react in liquids far differently than a solid chunk of metal would. Best of luck.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


February 27, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. What is the best way to electroplate Nickel to Carbide? It also needs to adhere very well for the after process.

Rick Shornak
Plating shop employee - Novi, Michigan, United States


A. Hi Rick. We appended your inquiry to an earlier thread. I can't say what's best, and have never done it, but it sounds like Wood's Nickel Strike after anodic sulphuric etching is a good method to try. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



February 25, 2014

Q. I am using a woods Ni Strike to plate a 6% cobalt Tungsten Carbide.
After alkaline cleaning the parts are rinsed, and placed in 25% HCl, rinsed in DI water, then into the Ni strike.
Should the surface be activated using HCl or H2SO4 prior to the strike?

Following the activation, product is rinsed in DI water, then into the Nickel Chloride strike.
After the nickel strike we rinse in water, then into electrolytic Ni sulfate; following this rinse in DI water and then into electrolytic gold.
Should there be an activation prior to the electrolytic nickel and an activation following this prior to gold?

Rob Sachs
- Morrisburg Ontario Canada


February 27, 2014

Q. If you use H2SO4 as an etchant for Tungsten Carbide no current, what would be a recommended % and time?

Rob Sachs [returning]
- Morrisburg Ontario Canada


February 28, 2014

A. We just electroplated Ni an trivalent Cr onto steel parts with tungsten carbide inserts without any special activation steps. Everything came out perfect.

jim treglio portrait
Jim Treglio
- Vista, California



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