Magnetite Cores

[cody]

I have been doing some work with magnetite(Fe3O4), or black sand, as a core material in electromagnets lately and thought i would post some stuff for any one interested. I got the idea from Robert Adams, who claimed that magnitite cores made his motors more efficient, I believe Bill Muller and Konhead also mentioned this. I can not claim this yet myself, but here are some of the things i have concluded from them. They make a weaker electromagnet and are not attracted by magnets as well as silicon-steel. Im not saying that makes them worse than silicon steel, they might just have better higher frequency applications or much lower losses to eddy currents or hysteresis. Its actually really easy to work with i think, i liked it better than welding rods, but thats just my opinion. I believe its a main component for metglass cores, which are high efficiency expensive cores from what Ive heard. I welcome anyone with any information pertaining to this to please post here, Im still trying to learn more myself. Here is a little clip I made going over the basic operation of making these cores.
YouTube - Magnetite Cores
Here is some basic wiki info on magnetite.
Magnetite - Wikipedia, the free encyclopedia

[Inquorate]

Thanks for that

It's something to keep in mind, even using filings and resin opens up lots of options for experiments with cores.

[ApEkV2]

That's awesome, and now I'm looking forward to making some magnet cores. Thanks for the vid cody.

[Jetijs]

Hi cody
I made some magnetite cores a while back, did not have time to test them properly yet.


The reddish core in the last picture is a mix of magnetite(Fe3O4) and hematite(Fe2O3). I used those materials because those two elements are the main things in black sand. Hematite is red-brown in color and a magnet attracts it only very weak. Such cores do not work well in traditional generators or electromagnets, but as we know, Muller motor is a whole different thing with the coil shorting at right timing and HV output In this case those cores might work great. We have yet to find that out.

[cody]

Thanks guys! Nice cores Jetijs, i was looking at the wiki info on it and it said magnetite was already composed with hematite. But im no chemist and i suppose you were trying to match the proportions of black sand, interesting. Im wondering if you noticed any difference between the two.

[slayer007]

Does this work good to make toroid cores for like a joule thief?
Or would a ferrite core be better.

[Jetijs]

Does this work good to make toroid cores for like a joule thief?
Or would a ferrite core be better.

Don't know about that, but these magnetite cores are very easy to make and machine. You just mix the magnetite with some epoxy resin that is used in glass fieber industry and then pour the mix in any form you need

[Jetijs]

Cody, yes, I wanted to mix the two components to match the natural black sand as close as possible. But as I said, I still have not performed any tests yet.

[Ted Ewert]

I've built quite a few magnetite cores. Some of the the advantages they have are:
Ease of construction
Resistance to heat build up when used with neodymium magnets.
High electrical resistance when mixed with resin.
High resistance to eddy currents.
Disadvantage:
Lower conductivity to magnetic flux.
Mechanically weaker than steel.
A very good core material is mixing magnetite with #7 steel shot. This combo is much more permeable, yet still maintains the desirable attributes of pure magnetite. BBs are another option, but they don't have the area density of small steel shot. Steel shot is also annealed for softness, which is perfect for core material.

Ted

[cody]

Thanks Ted! Some great info there. I would like to share some of my findings. At first i was concerned about the low electromagnetic field strength because it wasnt allowing my motor to work very well, actually it wasnt strong enough to work at all. Then i realized the problem wasnt my coils or cores, it was my magnets. I was using weak ceramic magnets on my rotor, the type bedini suggests. They attract very little to the core and repel very little as well. But then i tried some strong neo's and i started to see a light at the end of the tunnel. Much better preformance, good attraction and repulsion. I would not be able to use these strong magnets with a steel core in my coils, they would attract to much and not repel enough to be of any use. I think neodymium is defiantly the way to go with magnetite. The lindemann attraction rotor i was working on in the video isnt going to work, but thats ok, at least i know what direction to go now. Learn something new everyday.