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Topic: Electroform Ni-Co-Mo  (Read 382 times)

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Offline Enthalpy

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Electroform Ni-Co-Mo
« on: February 07, 2021, 05:21:13 PM »
Hello everyone!

I suggested repeatedly to electroform Ni and Ni-Co, possibly allied with Mo, for music instruments and more
 scienceforums and later and elsewhere
Strong electroformed alloys would serve many more uses. For instance rocket chambers are of nickel electrodeposited on an inner copper jacket where cooling channels have been milled. But what alloys might be possible?

Please remember I'm not reliable on electrochemistry.

Strong nickel alloys are known, mainly for superalloys used in gas turbines. They consist of Ni, 20% Cr, 0-20% Fe, <20% Co, <10% Mo, <5% Ti, ~1% Al, Nb, and some more. Nice source:
 Nickel and Its Alloys , monograph 106 by the National Bureau of Standards


Based on redox potentials, which are not the whole story for electrodeposition, Co (-0.26V) is fully compatible with Ni (-0.28V), and both are indeed codeposited routinely.

Mo (-0.20V) looks easy, and Ni-Mo compound precipitation knowingly hardens Ni alloys without embrittlement. Mo is a very strong candidate.

If Cr (-0.91V, forms an oxide layer) can be co-deposited, fine! Zn (-0.76V) is commonly deposited together with Cu (+0.52V) to make brass. My understanding is that Cr protects Ni alloys against corrosion as it does for steel, but isn't a vital hardening element. Since Ni and Co alloys resist corrosion enough at room temperature, Cr can be dropped.

Maybe Fe (-0.45V) can be co-deposited. It's present in some Ni superalloys, not in others. It must reduce the density and the cost, little more. Easily dropped.

Can Ti, Si, Zr, C, B, Al (-1.67V) be electrodeposited? I suppose not, based on their solubility, potential and oxide layer. Precipitates of Ni-Ti and Ni-Al compounds are very important hardeners of Ni superalloys, but ciao. C is undesired, Si doesn't seem useful. B is sometimes used in tiny amounts in superalloys, adiĆ³s.

Nb (-1.10V), or rather unseparated Nb+Ta, precipitates as Ni-Nb to harden superalloys. I suggest to try Ta (-0.60V) instead: same atom size, same effects in alloys. If deposition works despite the oxide (it does for Zn), electrodeposited Ni and Ni-Co have a second precipitation hardener.

W is sometimes added in tiny amounts. Re (+0.30V) could be a candidate equivalent.

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Cu-Zn brass is routinely deposited. Cu-Ni-Zn "nickel silver" must be about as difficult and is the common alloy for keyworks of woodwind instruments. Though, I want to make keys hollow and thin to be lighter and stiffer. Bigger diameters help, stronger alloys too, as inspired by nickel superalloys.

Lighter keys would be very appreciated at the German bassoon, at other instruments too, lighter and stiffer keys at the baritone saxophone.

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Since I'm here: the cooling jackets of rocket engines mention exotic Cu alloys meant to conduct well and be harder than pure Cu. The widely available Cu-Cr1Zr was developed for that purpose, along with few more. For electrical conductivity, but it's the same.

Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Electroform Ni-Co-Mo
« Reply #1 on: February 22, 2021, 06:06:47 AM »
Please remember I'm not reliable on electrochemistry.

Many more elements and alloys can be deposited than I had guessed. Here are composition examples from one paper:
  • Fe base material in that paper
  • Ni 80%
  • Co 6% and 95%
  • CoNi 65%+12%
  • V 1% from ammonium metavanadate
  • Cr 10% from banal salts
  • B 8% from KBH4 basic solution
If I extrapolate boldly from Fe-based to Ni+Co and Ni-based alloys: Cr may be possible and it lets Ni superalloys resist corrosion better. 20% Fe is feasible and serves in some Ni superalloys. 1% V is a useful hardener in Ni too. But the hardener B uses here a basic solution uncommon with the other elements.

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Fascinating too: electroform maraging steel Fe-NiCoMo. It would include the precipitation-hardener Ni+Mo but lack the important Ni+Ti. Whether Ta can replace Ti?

And could Co-20Cr-16Ni-7Mo-etc be electroformed? It combines fantastic corrosion resistance with good room-temperature strength. The standard cites also 2% Mn and <1.2% Si.

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Maybe gas turbine blades or complete blisks can be electroformed. Machining hollow blades takes time, spark-machining blisks too, electrodeposition can be cheaper.

Heat exchangers need intricate shapes with weld seams, solder seams or difficult machining. Superalloys would resist heat, corrosion and pressure. Electroforming would avoid assembly seams and difficult or impossible machining. Maybe a complete exchanger can be electroformed at once, or the tubes, plates... be made in a separate process or step and the manifolds deposited on them, possibly bored thereafter. Adolphe Sax patented welding by electrodeposition.

Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Electroform Ni-Co-Mo
« Reply #2 on: February 23, 2021, 06:32:32 PM »
Ahum. (1) Write (2) Read (3) Update.
  • Ta and Nb are not electrodeposited from aqueous electrolytes. Alas, aqueous is the usual choice for Ni, Co, Mo, etc.
  • W is not deposited alone, but its alloys are. Re is deposited. With close metallic atomic radius, Re could be an alternative.
  • Mn is commonly electrodeposited.

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