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Is there any material which is NOT conductive and IS magnetically attractive?

I am in need of a material which I can shape and use within a machine. It must be very attracted to magnets similarly to steel or iron. However it must be extremely electrically resistive, like plastic insulators or ceramic insulators.

Specifically, when a magnet is passed over the material the magnet should be very attracted to it, yet the material should not produce any internal electromagnetic eddy currents and cause electromagnetic braking.

I am currently considering an epoxy solution saturated with iron filings or BBs, but I am concerned they may touch each other within the solution and create large enough conductive sections that would allow the creation of electromagnetic eddy currents. Or might not be saturated enough to allow the high magnetic attraction required.

I would prefer a solid material to allow shaping for use as a part within a motor.

Also, superconductors are not an option.

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  • $\begingroup$ Perhaps a ferrite? $\endgroup$ – Kyle Kanos Feb 5 '15 at 1:20
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    $\begingroup$ Easy to do, mix iron dust with melted plastic, glue, clay etc; and let it harden to become solid $\endgroup$ – Maxim Umansky Feb 5 '15 at 1:30
  • $\begingroup$ Per my post: I am concerned they may touch each other within the solution and create large enough conductive sections that would allow the creation of electromagnetic eddy currents. Or might not be saturated enough to allow the high magnetic attraction required. $\endgroup$ – Don Feb 5 '15 at 1:55
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Yes, ferrite. According to page 8 of this brochure, Ferrite-NiZn has a resistivity of 10^4 Ohm·m. This is better than damp wood, at least. You can trade magnetic properties for resistivity by coating and embedding ferrite pellets in an insulator, as suggested in the comment above, but fashioning your own metamaterial will probably involve quite a bit of research and experimentation.

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  • $\begingroup$ While researching @KyleKanos 's comment, I found 'NiZn' to be the solution as well. Thank you for reinforcing that answer. I am now trying to determine the magnetic attractiveness (insert technical term here) to ensure magnets will be highly attracted to it. Also for experimentation I need to find a source for NiZn and am considering extracting it from NiZn rechargeable batteries. Unless someone can suggest a better source? $\endgroup$ – Don Feb 5 '15 at 4:05
  • $\begingroup$ @Don Whoops, hadn't seen Kyle's comment, sorry. As far as extracting it from batteries goes, don't bother. Batteries do not contain any ferrite. None. Check out [this][1], and compare it to the formula in the ferrite article. No relation whatsoever, except containing nickel and zinc atoms. You might try starting your quest here: amazon.com/Pcs-Ferrite-Tube-Cylindrical-NiZn/dp/B00S65KLG4/… [1]: en.wikipedia.org/wiki/… $\endgroup$ – Wolfram Schmied Feb 5 '15 at 4:17
  • $\begingroup$ Perfect. That is an excellent starting point. Just one final question to be sure it answers the original question. Is NiZn highly attracted to magnets? I am searching for the correct terms so I can find the answer too. $\endgroup$ – Don Feb 5 '15 at 4:49
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    $\begingroup$ "NiZn" is just shorthand for "nickel and zinc", that won't take you very far. You need to look for both "ferrite" and "NiZn": "A ferrite is a type of ceramic compound composed of iron oxide (Fe2O3) combined chemically with one or more additional metallic elements", the latter being the "NiZn" part in our case. I'm not sure what you mean by "highly attracted". They are of course not as strong as neodymium magnets, but the Wikipedia article says that ferrite is used in motors, so it would appear you're headed in the right direction. $\endgroup$ – Wolfram Schmied Feb 5 '15 at 12:40
  • $\begingroup$ That makes sense, thank you for the time working through this. I mean that if we take a neodymium magnet near a NiZn Ferrite block that it would stick to it with near or similar the force as if it were steel. Also it should not build it's own magnetic field, but I believe that's where the low permeability attribute comes in to overcome it very easily even if it does. $\endgroup$ – Don Feb 5 '15 at 12:55
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Not sure if this helps but I found some pads with the stickum on the back (peel and stick) would of bet my life they were rubber(even cut a piece out to make a new bottom of my sanding block which works great)....then I noticed a magnet stuck to it like steel (very flexible 1/16" thick pad can bend 180° and doesn't break until the bend is about 1/4th" apart) I decided to check and it is absolutely non conductive This is how I found your post trying to figure out what material it is. It comes from a wi-fi ,microwave,and other frequencies company. I wish I could post a pic

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  • $\begingroup$ It may be the material used for refrigerator magnetic pads. The flexible ones, used for advertising various brands or companies. Similar material (flexible) is used to ensure thigh closing of the refrigerator doors. $\endgroup$ – nasu Sep 1 '17 at 15:34
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Other materials that go in this category would be:

  • Soft magnetic composite (SMC)
  • Amorphous iron

SMC is a composite of small(microscopic) ferromagnetic particles which are coated with some kind of plastic. It can be formed into almost any shape and it isn't laminated. The ferromagnetic properties aren't as good as with other materials, but it has a permeability which is the same in every direction (not true for laminated steel, as the normal to the lamination surface will have lower permeability due to insulation layers). (not cheap, but cheaper than amorphous)

Amorphous iron on the other hand is made by a specific process where ferromagnetic particles are cooled down very fast (a few thousand Kelvin per second, as far as I remember). The structure isn't crystalline but amorphous, so it is basically a kind of glass. The conductivity is very low, and the magnetic properties are (to a good degree) retained. (Expensive stuff!).

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    $\begingroup$ Do you have a reference for the low conductivity of amorphous iron? How low? Liquid iron is pretty good conductor and is not crystalline. Why would amorphous iron be insulating? $\endgroup$ – nasu Sep 1 '17 at 15:31
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Iron Boron Silica AS STATED IN THE VIDEO Mixing Glass and Steel using Sunlight non-conductive https://www.youtube.com/watch?v=sy5-sMzGxdU

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