Mumetal grain size and magnetic properties correlation
Mumetal grain size and magnetic properties correlation
(OP)
I have a sample of transformer laminate (mumetal) with unknown magnetic properties. My goal is to achieve the same magnetic properties with raw material that has the same chemical composition and thickness, but I ca't measure the permeability results. Is it possible to do that by comparing the grain size/shape and repeat the heat treatment until they become the same?





RE: Mumetal grain size and magnetic properties correlation
Grain size is indeed one of factors which determine magnetics, at a certian range, the bigger the grain size, the less the grain boundaries, the less the pinning sites of magnetic domain displacement, and so the higher the permeability. However, as for Mumetal, the ratio of short-ranged disordered/ordered takes a big role to determine soft magnetics. A same grain size with a different disorder/order structure can create a big difference in permeability.
RE: Mumetal grain size and magnetic properties correlation
RE: Mumetal grain size and magnetic properties correlation
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RE: Mumetal grain size and magnetic properties correlation
Good one. well of corse, material will be from manufacturer or supplier but final parts with target properties have to be done "in the house". If it's possible, of course ;)
RE: Mumetal grain size and magnetic properties correlation
RE: Mumetal grain size and magnetic properties correlation
Ni76.6 Cu4.5 Mo3.3 Fe14.7 other% Mn, Si
Target permeability has to be approx. u5=11000 but as I mentioned in first post I can't measure it. Yes, I know it's low permeability for this kind of material but that's the subject of my post here.
RE: Mumetal grain size and magnetic properties correlation
I assume u5 is the permeabilty at H =.005 Oe at 60 Hz. 60-70,000 is expected. initial permeability at B=40Gs, 60 Hz is about 50-60,000. these are impedance permeabilties, if using inductance permeability, the vaules are even higher.
RE: Mumetal grain size and magnetic properties correlation
RE: Mumetal grain size and magnetic properties correlation
High temperature is for grain growth as well as effective removal of C, S. If the temperature is too low, you will get very small grain size and high amount of remaining C, S, both of which could bring you properties far away from desired.
b.t.w., even low Ni grades, say Carpenter High Perm 49, can give you 11,000 at .35mm heavy.
RE: Mumetal grain size and magnetic properties correlation
Yes, I know, but since my goal is to reconstruct the old design I decided to go with the same material as original. Thanks, I will post my results here.
RE: Mumetal grain size and magnetic properties correlation
RE: Mumetal grain size and magnetic properties correlation
RE: Mumetal grain size and magnetic properties correlation
RE: Mumetal grain size and magnetic properties correlation
RE: Mumetal grain size and magnetic properties correlation
RE: Mumetal grain size and magnetic properties correlation
RE: Mumetal grain size and magnetic properties correlation
There are lots of other methods to coat your strip.
I donot have a good idea how to create a thin oxide layer for high Ni lams, but you may try to bake at lower temperature, say 350C or lower(to prevent from damaging the formed structure during your previous cooling) for 30-60 minutes at oxygen bearing atmosphere. The exact tempreature and time may be determined by the thickness of oxide layer desired.
RE: Mumetal grain size and magnetic properties correlation