How can I find out what kind of core material this is?

[HMS-776]

I am working on a project and I need to find out what kind of core material this is...

Unfortuantely I cannot ask the person who had it because they no longer have it.
I don't think it's ferrite, the thickness is about .125", and the permeability is around 700-1000.
It had several coils on it and operated below 20kHz.

Anyone?

 

[Antiphon]

Looks like silicon steel. Typical transformer lamination.

 

[HMS-776]

Ok, is there any kind of silicon steel with permeability in the range of 700-1000?

I think it's all one piece which is .125" thick though...Isin't silicon steel only available in thin laminations?

 

[Antiphon]

Yes that's too thick. Have it analyzed. For a few hundred dollars you can find out what's in it and guess the alloy.

 

[Carl Pugh]

It's probably ferrite. It's deninitely not silicon steel. Could be some sort of powdered metal.
Why don't you get ferrite and see if it works.
Ferrite is very brittle, see if it breaks when struck with a hammer.

 

[HMS-776]

No it's not ferrite, the permeability is too low I believe for it to be ferrite.


If it's not ferrite or silicon steel what else could it be?

 

[Carl Pugh]

You may want to Google "powdered metal cores"
Some powdered metal cores are Permalloy, Molypermalloy, Kool Mu, Powdered Iron...
Just out of curiosity, why are you so sure the permeability is 700-1000?
Ferrite with a gap could have this permeability.

 

[HMS-776]

The core was actutally made from two of these cores back to back to form a square core.

The cores were held tightly together on a jig to prevent a gap. The coils and core were designed to achieve a high coupling coefficient and mutual inductance.

 

[metiman]

Some powdered metal cores are Permalloy, Molypermalloy, Kool Mu, Powdered Iron...

Any metal can be ground up into powder, no? Permalloy and molypermalloy are quite common (although very expensive) in laminations. Kool Mu is defiinitely a powdered only material though.

 

[jim hardy]

if they wanted precise inductance they controlled the air gap.

700 sounds low. i'll bet that includes their airgap which may be in thousandths.

look up permeability curves, they depend on flux level temperature frequency etc.
if you want precise inductance you include a gap to reduce those effects.