Comments for Mumetal

Comment on FAQ by nickmsl

nickmsl — Wed, 30 Mar 2011 15:22:51 +0000

Yes there are different heat treatments for Mumetal and different grades of Mumetal which has various trade names inc Supermalloy and Permalloy A. Take care with this particular trade name as it also is used for the 50%NiFe and the 36%NiFe grades. True mumetal should correspond to ASTM A753 and alloy 4 under this standard and is the only grade we use and has a nominal composition of 79% NI with 4% Mo and balance Fe. There is also a grade containing up to 5% Cu in replacement for most of the Mo but we do not use this grade since generally its properties are regarded as inferior.

Regarding heat treatment it must be heat treated as a last process normally this is in an atmosphere of pure dry hydrogen at a temperature of 1100-1170 degrees centigrade for 2-4 hours followed by cooling to below 250 degrees at a cooling rate around 170 degrees per hour

Grain size after this heat treatment should be large normally ASTM 9 or larger and can often be seen without any optical aid if the HT atmosphere is very good with a dewpoint better than -40 degrees centigrade. The disappearance of these grains is normally due to mild surface oxidation, mumetal is very oxidation resistant in air but the “super clean ” surface after heat treatment will oxidise mildly over time in normal room conditions.

I hope this helps , please feel free to see our website for more Heat Treatment and material details and do not hesitate to contact us if you require further help or information.

Comment on FAQ by Susan Hsiung

Susan Hsiung — Wed, 30 Mar 2011 08:44:04 +0000

Hi,
I’m trying to make an eddy current coil using mumetal as a core sensor in the coil. However I’ve come across some difficulties and haven’t succeeded yet. I was wondering if someone can assist me.
Are there different heat treatment procedures for mumetal depending on different applications?? The mumetal material that I used was also heat treated but I’m not sure if the treatment procedure was appropriate or not.
After doing heat treament under microscope I could see the crystal grains on the surface. However after a few months I found that the grains have started to disappear. Is this normal for grains to disappear as time passes by??
Besides mumetal, I have also tried supermalloy, permalloy..etc different kinds of NiFe alloy but I still did not suceed. The eddy current coil doesn’t work well. So I’m still wondering if it is the material problem or the heat treatment problem??
Any suggestions or comments will be greatly appreciated….!!!!
Thanks a lot!

Comment on FAQ by nickmsl

nickmsl — Thu, 24 Mar 2011 10:13:43 +0000

Dear Alex

The saturation induction of mu metal is 0.76 Tesla

Kind Regards

Comment on FAQ by nickmsl

nickmsl — Tue, 08 Feb 2011 09:37:35 +0000

Dear Sir,

After mumetal reaches its saturation point it will not attract additional external magnetic magnetic fields. A material such a Supra 50/Pure Iron has a higher saturation flux density and should be used.

Comment on FAQ by Tumen

Tumen — Tue, 08 Feb 2011 04:39:00 +0000

Dear Nick Murby,

Does the magnetic shielding material (mumetal) still attract extra external magnetic field (flux) after its state of saturation?

Comment on Mu Metal specifications by nickmsl

nickmsl — Wed, 15 Dec 2010 08:51:13 +0000

Dear Sir,

I enclose some sample data of mu metal curves at lower frequency which I believe displays the drop in permeability and what you are likely to expect in the MHz range. Unfortunately there has been no research at such a high frequency by any of the material manufacturers that I am aware of, which is primarily due to the poor efficiency of this material in this range (MuMax will be in the hundreds)

Sorry I cannot be of more assistance.

Kind Regards,

Comment on About by nickmsl

nickmsl — Wed, 15 Dec 2010 08:45:06 +0000

Dear Sir,

The Curie temperature in mu metal varies between a temperature range of 390-450 degrees centigrade, dependant on the chemical composition of the “brand” of the alloy. In the temperature range in question, (150-200 Deg C) mu metal will function normally without any derogatory effect, however we would not, as a general rule recommend usage above 300 Deg C.

Please feel free to contact me if you require any further information

Kind Regards,

Comment on About by nickolas Ptschelinzew

nickolas Ptschelinzew — Mon, 13 Dec 2010 19:00:25 +0000

I am a graduate student at the University of Florida working on a magnetic detection project. I would like to use Mu-metal shielding but am concerned about the curie temperature as I will be exposing it to temperatures as high as 150-200 C. Could you please provide me with any information about the magnetic shielding properties of mu-metal at these temperatures. Thank you

Nickolas

Comment on Typical Magnetic Shielding applications by jesus assis

jesus assis — Wed, 08 Dec 2010 22:30:52 +0000

Hi
I´m part of a research group in History in Sao Paulo, Brazil. We are trying to build a vessel to protect magnetic memories (like those used in pen drives) from external magnetic fields so that sensitive data can be stored for long periods (we mean historical periods).
Could yo please explain for us the differences between Mu-metal or Giron Magnetic shielding film?
Anyway, do you think this method (involving memory chips in mu-metal or anything alike) will really protect the data?
Thank you

Comment on Mu Metal specifications by Kamal Hadidi

Kamal Hadidi — Mon, 06 Dec 2010 21:40:37 +0000

Hello,

I would like to know the permeability of the mu metals you carry in the MHz region. I am interested in 2 MHz and their hysteresis loss at this frequency.

Thanks

Kamal Hadidi