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Participant

Join Date: Oct 2006
Posts: 3

Does carbon fiber disrupt magnetic flux?

10/21/2006 7:39 PM

If I were a permanent magnet in carbon fiber how would it affect the flux density?

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Guru

Join Date: Sep 2006
Posts: 4514
Good Answers: 88
#1

Re: Does carbon fiber disrupt magnetic flux?

10/22/2006 9:25 PM

Pure carbon? Are these fibers electrically conductive, as would be pure carbon, or are they a composite material which may not, in fact, be electrically conductive?

If pure carbon - and if you've not done this already - I'd google "carbon, carbon fiber, paramagnetic, diamagnetic" or some combination of these terms.

Paramagnetism and diamagnetism are probably the only factors you need be concerned with if the magnetic field is fairly constant (yes, your question mentioned only permanent magnets, but what is the immediate environment like? Will these magnets also be exposed to substantial and possibly high-frequency external magnetic fields, for instance?) The effects of para- and diamagnetism aren't particularly pronounced as a rule, but then, I have no idea of what concerns motivate your question.

--Europium

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Member

Join Date: Sep 2006
Posts: 6
#2

Re: Does carbon fiber disrupt magnetic flux?

10/25/2006 1:54 AM

Permeability of the item may be what you should look at. The ability to conduct electricity is not synomous with the ability to conduct flux. For example, stainless steel, alumunim, copper, gold or silver are very poor conductors of flux. Low grade steel on the otherhand is a very good conductor of flux. High carbon steel is a poorer conductor of flux, however retains magnetic field once charged. A demagnetization curve and permeabilities of your materials would be what to look for.

For argument sake, if your "carbon fiber" encases the fixed magnet and is highly permeable then you may short the magnet out and destroy your flux. If the permeability is low and the field needs to be such that it was in air without the carbon fiber then your magnetic field may not be affected for your purpose. On the other hand if you are putting carbon fiber between two fixed magnets so to add the two fields then you are adding the equivalent of an air gap. Depending on the strength of the magnet this 1/8 inch may as well be infinity in your application. Probably you should do a FEMM analysis. What are you trying to do?

Brian

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Guru

Join Date: Sep 2006
Posts: 4514
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#3
In reply to #2

Re: Does carbon fiber disrupt magnetic flux?

10/25/2006 5:23 AM

I think perhaps you missed the more subtle implications of my questions. My question about the electrical conductivity of these fibers has little relevance so long as the surrounding environment does not contain highly-variable magnetic fields. If the environment does contain such fields, these fields will induce electric currents into the fiber. These currents will generate heat and, perhaps more importantly, their own counter-active magnetic fields. As I have no idea of the poster's motivations for asking this question, nor any idea of the application details, I'm trying to accommodate any case I can think of that the poster might have had in mind. The poster has not responded since posting the original question. Pure carbon fiber has little permeability, but a concern about permeability was not my motive in asking about the electrical conductivity. The permanent magnet surrounded by carbon fiber exists in a larger environment, whatever environment that may be. It was the external environment that motivated my question.

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Participant

Join Date: Jul 2015
Posts: 1
#4

Re: Does carbon fiber disrupt magnetic flux?

07/09/2015 8:50 PM

Another question:

Using magnets with carbon fiber, is it possible to induce a current as you can with copper wire?

If so would it be better than copper as CF's heat dissipation is better?

regards,

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