Electroform Ni-Co-Mo

[Enthalpy]

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, adiós.

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.

==========

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.

==========

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

[Enthalpy]

On 2/7/2021 at 11:25 PM, Enthalpy said:

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.

==========

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.

==========

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

[Enthalpy]

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.

[Enthalpy]

Ni serves to make multilayer ceramic capacitors (MLCC). Depending on the manufacturer and the model hence the use (radiofrequencies), it can constitute the stacked electrodes and the barrier against diffusion and dissolution against solder at the terminals. The stack of electrodes and dielectric is sintered at once from nanopowder, while the barrier is electrodeposited on the sintered metallic terminals.
TDK - Murata - Johanson

Ni is ferromagnetic, which badly increases its losses by Kelvin effect (skin effect) at radiofrequencies. Pd was an answer for the terminals of radiofrequency capacitors but is abandoned due to cost.

Maybe Ni alloyed with Cu or Mo brings something. All Ni-Co are ferromagnetic, but 38% Cu or 20% Mo make Ni nonmagnetic (electronic components must operate at -55°C, these amounts are for RT) and they keep the melting point of Ni, so the change is hopefully easier. Ni-Mo was already electroformed.
polymtl - worldscientific
Mo conducts electricity like Ni does, it behaves even better than Ni in liquid metals (solder) and it resists corrosion nicely, so maybe NiMo is good too.

Marc Schaefer, aka Enthalpy