D4RR3N
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Melting Lanthanum metal in electric furnace
I have some Lanthanum metal I want to melt in a furnace under an argon atmosphere. What would be the best crucible to use?
I don’t think I can use a graphite crucible as it will react with the molten lanthanum metal to form Lanthanum Carbide.
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weiming1998
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Probably a nickel vessel is your cheapest option. Wash the entire thing with acid to get rid of the oxide layer, lest a thermite reaction forms and
destroys your vessel. A platinum vessel is the best and safest option, but that is too expensive.
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D4RR3N
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Quote: Originally posted by weiming1998  | | Probably a nickel vessel is your cheapest option. Wash the entire thing with acid to get rid of the oxide layer, lest a thermite reaction forms and
destroys your vessel. A platinum vessel is the best and safest option, but that is too expensive. |
Would a ceramic, silica or aluminium oxide based crucible react?
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Zan Divine
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Lanthanum, huh? You don't like the easy things apparently...
Ideally, La is induction melted in vacuo in W(preferred) or Ta.
Molten La can reduce most common refractories including MgO, BeO, Al2O3, SiO2, ZrO2, and ThO2.
Once molten, La is usually cast into water-cooled copper molds (which seem to work for damn near anything) under Ar.
If you do a good job, you'll get soft, easily cut metal.
If you have O2 contamination you will see the usual hardening caused by ill-fitting impurities situated at grain-boundaries.
[Edited on 12-2-2012 by Zan Divine]
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D4RR3N
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I’m planning to use a desktop resistance heated furnace with a max temp of 1100C. There is a hole at the back where you would normally insert a
temperature probe however I found that a rubber hose fits it perfectly. I have a cylinder of argon gas from a tig welder which I intend to fix to the
hose.
The furnace is obviously not air tight but I think if I use positive pressure all air should be excluded from the interior of the furnace i.e.
pressure of Ar inside furnace chamber is greater then air pressure outside.
[Edited on 12-2-2012 by D4RR3N]
[Edited on 13-2-2012 by D4RR3N]
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weiming1998
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| Quote: Originally posted by D4RR3N | | Quote: Originally posted by weiming1998 | | Probably a nickel vessel is your cheapest option. Wash the entire thing with acid to get rid of the oxide layer, lest a thermite reaction forms and
destroys your vessel. A platinum vessel is the best and safest option, but that is too expensive. |
Would a ceramic, silica or aluminium oxide based crucible react? |
No, because they are oxides, and La is very reactive to the point that it will form a thermite reaction with the oxides, even in the absence of
oxygen, and destroy your vessel. Only a pure, unreactive metal vessel washed with acids first will work.
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D4RR3N
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Ok I have a question about these nickel crucibles. I have made nickel brass in my furnace before so I know that nickel will dissolve in molten brass
(copper+zinc). How do I know that the molten lanthanum wont eat a hole straight through the nickel crucible. I’m sure if you put brass into one of
these crucibles it would eat through it.
Obviously I would prefer to use a nickel crucible as they are easy to obtain and not that expensive. I cant even find a Ta or W crucible other then
manufacturers who require bulk ordering, I’m sure they will be very expensive too!
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weiming1998
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| Quote: Originally posted by D4RR3N | Ok I have a question about these nickel crucibles. I have made nickel brass in my furnace before so I know that nickel will dissolve in molten brass
(copper+zinc). How do I know that the molten lanthanum wont eat a hole straight through the nickel crucible. I’m sure if you put brass into one of
these crucibles it would eat through it.
Obviously I would prefer to use a nickel crucible as they are easy to obtain and not that expensive. I cant even find a Ta or W crucible other then
manufacturers who require bulk ordering, I’m sure they will be very expensive too!
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I don't know about that. Perhaps you can try melting very small amounts of La first, if it corrodes nickel to any degree, turn off the flame and use
other vessels.
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