Electrodeposition of Tungsten or other Very Hard Material

A. Hi Michael. Tungsten cannot be electroplated from a conventional aqueous bath, but that is not the only coating technology available. Chromium is probably one of the hardest electroplateable materials but maybe you already considered that one. Composite plating with diamond or other particles may be useful to you. Rhodium is hard, but extraordinarily expensive and perhaps not thick enough.

Chlorides should drive the stress in nickel electroplating through the roof.

Please tell us what you are trying to do. Thanks!

A. Stress in nickel can be induced by almost anything, but one surefire way of doing it is to add chloride. Sulphamate nickel has been designed to offer low stress deposits, but you can always use high sulphate and/or high chloride baths.

For hard materials, probably the hardest is hard chromium, although you can also get hard electroless nickel with a high phosphorus content. You certainly cannot electrodeposit pure tungsten, (although there are some claims you can) but you can deposit binary systems using tungsten and (say) chromium or other metals. If you want to deposit pure tungsten, try vacuum technology; this will also let you put down tungsten nitride, which has a hardness well in excess of 2,000 Hv. Perhaps you would like to tell a bit more about what you are doing?

A. I think that he is looking for sodium tungstannate, which is added to nickel plating solutions to increase the hardness. Twenty years ago, there were several articles and formulas in print. I am fairly sure that it is still being used in some brush plating solutions, with a very limited build up possible -- i.e., a cap coat.

A. Tungsten can be plated from a melt of sodium tungstate with a small addition of sodium pyrosulphate. Temperature 1650 °F

A. The electrical properties of nickel are not too far from tungsten. Nickel can be easily plated on copper, and, I believe, will not amalgamate with mercury at ambient temperatures.

A. Hi Trenton. Access to Finishing.com is free, but if you have found papers on another site which require payment to view, we can't help with that.

You can do an electroless deposit of Ni-P-W alloy with up to 20% tungsten according to Mallory & Hajdu .
Gawrilov's Gawrilov's Chemical (Electroless) Nickel Plating [affil link on Amazon, ... on AbeBooks] very briefly mentions electroless Ni-P-W alloys. Brenner's "Electrodeposition of Alloys" has a whole chapter on tungsten alloys, but that 1400-page tome is so exhaustive that I don't have the necessary several hours to study it and summarize :-(

Iron is notable for not forming amalgams with mercury. Could the copper be plated with iron, kept in an inert gas environment, and maintain low enough resistance to convey the electricity to the copper channel?

Regards,

Hi Jeffrey

I've been advised that only Iron and Tungsten are not amalgamated, thank you for your reply.

Hi Ted

Paywalled not by finishing.com but by other technical paper repositories, and I'm not asking for help to circumvent that, but perhaps for a solution to my problem from someone with that knowledge.

I'm going to try Ni-P-W on Cu and pickle that in Hg to see if the Ni is amalgamated out the alloy. The process is cheap. Might also try some Moly.

The resistivity of Iron is too high.

Another option for me (and by the look of things, the best) is to try CVD Graphene on Cu, but once more, I cannot find any info on the interaction between the two.

Thank you for your reply.

Kind Regards

A. I believe nickel and or its salts are capable of amalgamation with Hg. Especially as it is very similar and closely related to noble metals it is highly likely that it will amalgamate. I seem to remember that some noble metals will not amalgamate. Perhaps palladium, rhodium or platinum but I don't have a reference.

A. Hi Jean. I think a PVD vacuum process would be necessary. I'm not aware of electroless tungsten and strongly doubt that it is possible (but see the earlier entries about alloys). Good luck.

Regards,

? Hi Jerry. Can you tell us anything about what they are doing -- like thickness, purity, method of application? What the component is so we can visualize whether line of sight methods are useable, the criticality of thickness distribution, etc.? Maybe it would be ideal if the shop doing the work described the problem? Thanks.

Regards,

A. Hi Bill. Easiest would probably be to just plate at too high a current density, generating a "burnt" deposit. Good luck.

Regards,

A. Hi Lava. Hi Ron. Brenner's "Electrodeposition of Alloys".
has a 66-page chapter on tungsten alloy deposition, including about 10 pages just addressing a number of hypotheses about why tungsten cannot be plated from an aqueous or organic bath but alloys can, especially with nickel or iron. It's an unsolved mystery so far.

Regards,

A. Electroplating of tungsten from water bath:
https://sci-hub.tw/10.1149/1.3497829
Fink, C. G., & Jones, F. L. (1931). The Electrodeposition of Tungsten from Aqueous Solutions. Transactions of The Electrochemical Society, 59(1), 461. doi:10.1149/1.3497829

  Hi Pavel. Thanks for the reference, but it was discredited. Fink & Jones were unable to plate any thicker than a fraction of a micron, and later researchers have repeatedly confirmed that it was a tungsten-iron alloy rather than tungsten.

Brenner's "Electrodeposition of Alloys" has the very interesting story of this paper, and does credit them with the first progress towards tungsten alloy plating .

Regards,

  Hi again, Pavel. There may have been progress since Brenner (pub. 1963). Maybe try searching scholar.google.com and surfacequery.com

Luck & Regards,