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Author Topic: Is Liquid Iron Magnetic?  (Read 9959 times)

Offline JoeThomson

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Is Liquid Iron Magnetic?
« on: 03/08/2009 13:19:29 »
Is liquid iron magnetic?

If it is and you make it flow in a particular way (with magnets), will this magnetise the liquid iron?

Thanks

Joe
« Last Edit: 03/08/2009 13:22:13 by JoeThomson »


 

Offline LeeE

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Is Liquid Iron Magnetic?
« Reply #1 on: 03/08/2009 15:40:25 »
Wikipedia gives the Curie point for Iron as 768 C and it's melting point as 1538 C, so no, liquid Iron is not magnetic.
 

Offline sveur

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Is Liquid Iron Magnetic?
« Reply #2 on: 03/08/2009 21:19:13 »
It's not my (magnetic) field, but from what I've read theres something called ferrofluids. Its a way to make a liquid with iron particles at room temperature. So liquid iron is not magnetic (if Leee is right) but a ferrofluid is. Read the second paragraph in the wiki article.

"Ferrofluids are composed of nanoscale particles (diameter usually 10 nanometers or less) of magnetite, hematite or some other compound containing iron."

Theres a very amusing video, and several related ones, here:
And a wiki article here: newbielink:http://en.wikipedia.org/wiki/Ferrofluid [nonactive]

 

Offline wanhafizi

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Is Liquid Iron Magnetic?
« Reply #3 on: 04/08/2009 12:19:06 »
Yes, ferrofluid is magnetic.

But it is not liquid iron.

It is made from solid nanoscale iron particles suspended in some oil based liquid, kinda like iron-paste, if you like.
« Last Edit: 04/08/2009 12:21:23 by wanhafizi »
 

Offline LeeE

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Is Liquid Iron Magnetic?
« Reply #4 on: 04/08/2009 20:14:40 »
Yes, ferrofluid is not liquid iron, as wanhafizi says.

I first heard of ferrofluids when they were used in loudspeaker drive units, to thermally couple the moving drive coil to the static permanent magnet, so that the PM could act as a heat sink for the coil.  Being magnetic kept it in place and stopped it running out.
 

Offline DoctorBeaver

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Is Liquid Iron Magnetic?
« Reply #5 on: 05/08/2009 10:03:17 »
As an extra question - is liquid iron an electrical conductor?
 

Offline LeeE

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Is Liquid Iron Magnetic?
« Reply #6 on: 05/08/2009 12:38:31 »
Do you mean molten iron or ferrofluid?

I suspect that the answer in both cases is yes.  Aluminium is non-magnetic but still conductive, and Mercury is molten but also conductive.  The windings in voice coils are enameled and thus insulated.
 

Offline JoeThomson

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Is Liquid Iron Magnetic?
« Reply #7 on: 05/08/2009 13:30:07 »
Molten Iron is what I meant.

I have read a bit about the curie temperature on Wikipedia. It says: 'Above the Curie point, the material is purely paramagnetic' What I gathered was that it is still attracted by magnets but does not retain any magnetic properties?

Under Paramagnetism on Wikipedia it says: 'Paramagnetic materials are attracted to magnetic fields'

So I'm guessing that molten iron is attracted to magnetic fields?

If the attraction force reduces with temperature, does anyone know how to find out the difference in attraction from say a block of Iron at room temperature and a pool of molten iron? Or even roughly as a % difference?
 

Offline JoeThomson

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Is Liquid Iron Magnetic?
« Reply #8 on: 06/08/2009 21:52:48 »
newbielink:http://www.springerlink.com/content/kq08u46714423x15/fulltext.pdf?page=1 [nonactive]

In this sample of a paper, it says that someone has made molten iron move up a slope under the influence of an electromagnetic field...

Surely molten iron is magnetic?
 

Offline LeeE

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Is Liquid Iron Magnetic?
« Reply #9 on: 07/08/2009 14:20:15 »
Hmm...  that's interesting.  I wonder if they've managed to induce a series of repulsive currents in the molten iron that are acting directly upon each other, rather than the magnetic properties of the material itself.  I guess I'd have to read it sometime.
 

Offline daveshorts

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Is Liquid Iron Magnetic?
« Reply #10 on: 12/08/2009 09:36:16 »
The hint is in the title of the paper - "regulating the tapping of molten iron with a changing magnetic field" - they are using eddy currents - find out more from this garage science

They use the conductivity of molten iron to heat it up in various sophisticated steel making processes, I think mostly by induction. The conductivity will however probably be lower than cold steel, as the disorder and movement of the atoms will tend to cause more collisions with electrons.
 

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Is Liquid Iron Magnetic?
« Reply #10 on: 12/08/2009 09:36:16 »

 

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