Subject: NEEDED: High-temp non-magnetic metal

From: [email-masked] (John M. VerBurg)
Date: 2 May 1996 07:52:12 GMT

Hi Everyone.

 I am trying to find a high temperature alloy that is completely 
non-magnetic. I am trying to build a heating element that will have a
continuous operating temperature of 1000 C.  It will be used to heat nitrogen
gas. The metal must be completely non-magnetic as it will be placed in an 
8.46 Tesla (84,000 gauss) superconducting magnet. I have tried 304 stainless 
and inconel and they are both still too magnetic for my purposes. I am 
considering titanium, but cannot find a supplier. If anyone can direct me 
to a supplier of titanium tubing or can suggest alternative alloys, I 
would appreciate it greatly. BTW, the dimensions for the tubing is .250" 
OD,  > .1875" ID x 12" long. If you have any laying around, I would be 
interested in purchasing it from you.

Thanks,

John VerBurg - Graduate Student
Dept of Chemistry
Indiana University
Bloomington, Indiana USA

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From: [email-masked]
Date: 2 May 1996 14:59:22 GMT

>John VerBurg - Graduate Student

Try Uniform Tube (UTI Corp)
      Collegeville, PA
      (215) 539-0700

They might have a scrap piece in stock, or could draw a lot for you.
(you do have an infinite budget, right?)

Also consider sapphire or ceramic (alumina) tubing - does it *have*
to be bent?

===========================================================

 1959 BMW R50                                           Jim Rozen              
 1969 BMW R60US                                (JRR0 @ watson.ibm.com)                 
 1975 BMW R75/6    (The "new" one)        

===========================================================

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From: [email-masked] (Richard W. Klopp)
Date: 2 May 1996 23:14:39 GMT

> >8.46 Tesla (84,000 gauss) superconducting magnet.
> 

If it's to be a heating element, it has to be conductive, which sapphire &
alumina (which is mostly polycrystalline sapphire) are not. Silicon
carbide ceramic is a nonmagnetic semiconductor, and titanium diboride
ceramic is a nonmagnetic condiuctor, though rather expensive. How about
graphite heating elements?

-- 
Rich Klopp                      Do your parents know you're in here?
[email-masked]

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From: [email-masked] (Charles Lewton-Brain)
Date: Thu, 02 May 1996 19:46:41 -0600

Consider Niobium, platinum (ouch$), as well.

For info on titanium try:

Bill Seeley
Reactive metals
800-876-3434

and

 http://www.titanium.com/tech.html 
Titanium industries reference site.

Good luck

Charles

-- 
Charles Lewton-Brain
Brain Press, Box 1624 Ste M
Calgary, Alberta, T2P 2L7, Canada
fax:403-283-9053
Email: [email-masked]

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From: Jeffrey Prothero <[email-masked]>
Date: Thu, 2 May 1996 18:45:15 -0700

A lot of titanium has enough iron impurities included that there is some
magnetic qualities.  Some Titanium from the xUSSR was non-magnetic (
possibly used for submarine construction ).
			Cheers,

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From: [email-masked] (James Kirkpatrick)
Date: 3 May 96 09:07:28 MDT

In article <[email-masked]>, [email-masked] (John M. VerBurg) writes:
|>Hi Everyone.
|>
|> I am trying to find a high temperature alloy that is completely 
|>non-magnetic. I am trying to build a heating element that will have a
|>continuous operating temperature of 1000 C.  It will be used to heat nitrogen
|>gas. The metal must be completely non-magnetic as it will be placed in an 
|>8.46 Tesla (84,000 gauss) superconducting magnet. I have tried 304 stainless 
|>and inconel and they are both still too magnetic for my purposes. I am 
|>considering titanium, but cannot find a supplier. If anyone can direct me 
|>to a supplier of titanium tubing or can suggest alternative alloys, I 
|>would appreciate it greatly. BTW, the dimensions for the tubing is .250" 
|>OD,  > .1875" ID x 12" long. If you have any laying around, I would be

One of the more interesting questions of late!

The FAQ lists a few suppliers of titanium and/or titanium products.  In
no particular order:

   -  Premier Fastener Company
      495 E. Parr Blvd
      Reno, NV  89512
      (800) 654-6333

      March 4, 1995:  It was mentioned that these folks have titanium
      files.  Not cheap, but they "last like crazy".

   -  Reactive Metals Studio
      Box 890
      Clarkdale, AZ 86324
      (800) 876-3434, (520) 634-3434
      [email-masked]

      Titanium, niobium, mokume-gane, shakudo and shibuichi metals.
      Supplies for anodizing reactive metals (this does NOT include
      aluminum).  Also an extensive line of findings, Sparkie welders
      and other supplies.  Free catalog.

   -  Robin Materials
      1951-T Colony St.
      Mountain View, CA 94843
      (415) 966-1533, (415) 966-1533 (FAX)
      http://www.rmat.com   or e-mail: [email-masked]

      "Specialty metals since 1981"  "Rare alloys & non-standard sizes".
      For example, titanium, invar, inconel, and so on.

   -  Tico
      Michigan
      (810) 478-4700

      Mentioned in a post 7/20/95, as a source of Titanium tubing.
      Minimum order is $100.

You might also try a web indexer like Alta Vista, keyword "titanium"
and wade through the results!

As for other non-magnetic materials, I have no clue :-(.  Maybe a
conductive ceramic or other non-metal?

Jim

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From: [email-masked]
Date: 3 May 1996 20:02:25 GMT

>graphite heating elements?

I guess the question was sort of unclear... my original response was
based on the idea that the tubing was only to *contain* the gas, and
there would be a heater wound around it.  

Sapphire tubing (available from Saphikon) has a pretty high thermal
conductivity.   The only problem with silicon carbide might be that it
is typically sintered with a cobalt binder (magnetic) - at least that's
what I've found in SiC tooling.

Perhaps the original poster could elaborate on his needs?

 1959 BMW R50                                           Jim Rozen

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From: [email-masked] (John M. VerBurg)
Date: 4 May 1996 23:46:09 GMT

[email-masked] wrote:

: Perhaps the original poster could elaborate on his needs?

Since you asked:

I am trying to build a high tempeature apparatus to perform magnetic
resonance studies on lthium conducting glasses. The end result of my
research might be a recyclable glass battery which may replace less
environmentally friendly nickel cadmium or lead acid batteries.
 
  The requirements for the heater are: A completely non-magnetic heating
element with a continuous operating temperature of 1000 C. It will be used
to heat nitrogen gas. I believe I can negate the induced field created by
the electric current passing through the heater by running a DC current
through a series of heating element wire that alternaterly run parallel
and anti-parallel to the large static magnetic field. I have thought of
using platinum wire, but the surface area is too small to heat the volume
of gas I need to such a temperature. I want to avoid winding a coiled
resistence wire, b/c it would be much more difficult to negate the current
induced M.F. 
    I would like a cartridge type design, but none availble go to such
temperatures nor are non-magnetic. The heating element must also have the
current leads on only one end. 
    I have thought of using resistence wire imbedded in silicon carbide,
but I cannot machine SiC with the equipment I have available. I could
imbed it in SiC powder, but then I need sheathing material. I have though
about the castable SiC, but I do not have any experience with it.

  In summary, I need a heating element that has the following properties:

No net permanent magnetic moment, non-inductively wound, with any
resultant field orthogonal to the large static field, single ended leads,
large surface area, with a continuous operating temperature of 1000 C,
stable in an N2 or air atmosphere. The maximum dimension are: .250" O.D. x
13" long.  
  
To all who have responded: THANKS!

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From: Jeffrey Lindemuth <[email-masked]>
Date: Sat, 04 May 1996 22:40:45 -0400

> graphite heating elements?

If you are looking for a non-magnetic heater element, Nichrome 80/20 (80% Nickel 20% Chromium) is non- 
magnetic. It can be purchased in a wide variety of wire gauges and will operate to 1000 C. If you are 
looking for a non-magnetic material for the heater walls and inconel is not satisfactory then things get 
harder. Using ceramics becomes difficult since most likely the heating element will be in a vacuum space. 
The orginal posting also mentioned 304 SS. This material, although non-magnetic, will undergo a phase 
transition at about 700-800 C (I forget the exact temperature) and will become magnetic when cooled to 
room temperature.

Don't forget the current in the heater element will produce its own magnetic field, so typically the 
heater elements are wound with wire in a manner to minimize the magentic field from the heater current.

Jeff Lindemuth
[email-masked]

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From: Richard Hager <[email-masked]>
Date: Sat, 11 May 1996 11:42:38 -0500

John M. VerBurg wrote:
 
> to heat nitrogen gas.

-- 

Maybe I'm missing something here, but WHY heat the gas IN the magnetic field?

Why not just heat it right outside the field, and tube it a few inches into 
the experiment area?  In my experience, when a problem seems insoluble, it's 
usually because I'm trying to solve the wrong problem!

While the description given for the heater needs was very detailed, there 
wasn't any description of the overall apparatus itself, nor any explanation 
for why the gas -had- to be heated -within- the field.

In regards to field-cancelling windings, it's been my experience that you can 
'never' fully cancel the field.  There will always be a residual or an 
asymmetry.  I wouldn't count on the 'anti-parallel winding' method.

In large (utility) transformer design, one of the toughest design challenges 
is the physical support of the windings.  They are of course non-magnetic 
copper, but the flowing current produces thousands of pounds of shear forces.

My suggestion:  Go back to the top level and rethink the overall 
setup.  There's probably a much simpler and more cost-effective way to perform 
this experiment.

Let us know!

        Richard Hager

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