High temperature application

[NOx]

I have an application where I need to utilise a magnet of some description to be able to mount onto the side of steel plate which is heated to 400 deg C. Does anybody no of a manufacturer who can advise on lifespan/degradation etc.
The magnet only needs to be 100 mm square.

 

[hacksaw]

No. Use a clamp or weld it.

 

[UKpete]

Sintered AlNiCo magnets will operate continuously up to 500degC, see:

http://www.magnequench.com/products/magnetpdf/KoerzitS.pdf

This is still a fairly common magnet type.

I don't know what the magnetic properties of steel are at high temperature though, that may need looking at.

 

[hacksaw]

with all due respect, the temperature associated with recrystallization does not represent the maximum temperature at which the material can be useful(as a magnet).

there is a progressive loss of strength with increased temperature to the point of having little or no useful magnetic strength at some temperature. there is a second temperature above which the magnetic properties (in some cases) is irreversibly lost and cannot be recovered by additional heat treating.

 

[UKpete]

Hi hacksaw.

I'm not sure what NOx intends, but AlNiCo will certainly work as a PM at 400°C. The datasheet (my earlier link) states that it can be used up to 500°C - I can't see any ambiguity, have a read through. See also:

http://www.hitachi-metals.co.jp/e/prod/prod03/p03_02.html.

NOx - further to my comment regarding the magnetic properties of steel, see:

http://www.ndt-ed.org/EducationResources/CommunityCollege/MagParticle/Physics/Demagnetization.htm

This gives the Curie temperature for steel as 770°C. So I believe that the combination of steel and AlNiCo will be satisfactory at the temperature you state.

 

[hacksaw]

still question of suitability of a magnet design for the purpose stated. retaining intrinsic properties after exposure to the service temperature is only one aspect of the problem. to go beyond that, specific details of the application are required.

Alnico doe not tolerate large air gaps well and generally requires in-place charging. its performance on a weight basis is also questionable given its relative low coercivity. the devil is in the details

 

[UKpete]

I agree but we don't really know what NOx is intending to do.

 

[Magnetman2]

Nox. Here at Swift Levick we manufacture Cast Alnico which is good to up to 450 C. There are some losses associated with working at these high temperatures but these can usually be accomodated in the designs. I would advise against sintered alniov becasue of the size. Sintered Alnico works best for high volumes of small magnets. A good website to check is

http://www.arnoldmagnetics.com

if you check out the Magnetic Technology Centre section there several very useful "Tech Tips"

 

[mac2]

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