Material Selection for Cooling Plate

[gphatch]

We are looking to use a material in a special cooling plate for a vacuum application. It must have the following characteristics:

1) Non-magnetic [key criteria].
2) Really low electrical conductivity.
3) Really high thermal conductivity.
4) Really high tensile strength.
5) Non-outgassing.
6) Weldable.
7) Machinable.

Current material is 316 SS - can anyone come up with a better suggestion?

Thanks!


Gareth P. Hatch, Ph.D.
Director of Technology
Dexter Magnetic Technologies

http://www.dextermag.com

 

[hacksaw]

you can always do better than 316 but meeting your objectives is another matter.

how are you dealing with 316 propensity to develop ferromagnetic properties over time?

 

[gphatch]

It is my understanding that 316 develops negligible ferromagnetic characteristics when compared to, say, 301 or 302 - and that would be under severe deformation and / or cryogenic conditions, right?

We are using this plate near a magnetic assembly, hence we don't want it to be magnetic. We want the material to have good thermal conductivity, so the plate can do it s job [cooling] - but low electrical conductivity to reduce the creation of eddy currents [the magnet assembly moves].

Thanks!

Gareth P. Hatch, Ph.D.
Director of Technology
Dexter Magnetic Technologies

http://www.dextermag.com

 

[hacksaw]

prolonged field annealing produces surprizing results but it depending on the composition (or grade )of your 316. you might need a coupon test.

eddy currents are a function of your metal thickness, the structure of your platen, and the speed of your magnet.

how are you cooling the plate? what do you mean by low outgassing: it means one thing in an annealing furnace another in uhv.

 

[gphatch]

Thanks for the comments hacksaw.

We tried this with aluminum, exact same dimensions of the plate, and the eddy currents killed us. The plate is being cooled underneath by flowing water at 20 PSI pressure. The plate is actually more of an enclosed pocket.

Low outgassing refers to the fact that this will be used in a vacuum system.

Gareth P. Hatch, Ph.D.
Director of Technology
Dexter Magnetic Technologies

http://www.dextermag.com

 

[rnd2]

http://www.goodfellow.com/csp/active/gfMaterialTables.csp?type=01&prop=MAG

Check titanium alloys

 

[hacksaw]

you can break up the eddy currents quite easily by your mechanical design regardless of aluminum or stainless.

aluminum is not considered low outgassing in some vacuum app's because of its vapor pressure at temperature and its tendency for thick oxide layers (depending on surface treatment and alloy grade), and its ability to pick up abient gases. it is fine in most industrial vacuum environments.