Cold-tolerant insulators?

I need to make some spacers out of a non-conductive material that will not crumble when chilled with liquid nitrogen. I'm not looking
for anything to remain flexible or anything, just to tolerate the temperature cycling without damage. How well does phenolic, for example, take this kind of treatment? How about teflon?
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Paul Ciszek wrote:

How fast will it thermally cycled? I think a lot of ceramics would work if they are not thermal shocked by rapid cycling/heating. Even if you have rapid thermal cycling, aluminum nitride or beryllium oxide might work (both have good thermal conductivity and are used for electronic substrates) Cordierite may be a viable option - low thermal expansion, it's dirt cheap and readily available (but not very strong)
http://www.du-co.com/applications/#4 - they maybe able to fabricate parts for you at reasonable prices.
http://www.thomasnet.com/products/cordierite-ceramics-19881275-1.html
http://en.wikipedia.org/wiki/Cordierite
Gregg
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Paul Ciszek wrote:

I know of workers who use polystyrene foam (coffee cup stuff) and similar closed cell polymers to contain liquid nitrogen.
It is no big deal.
You must have never handled the stuff in a lab.
Jim
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Sure, styrofoam makes a great *container* for LN2. But that's not what I asked.

Styrofoam is not dimensionally stable--it squishes. As a spacer between two metal parts, it stinks.

There is no need be insulting.
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Paul,
It'd be really helpful if you could describe the application more completely.
There's a huge number of insulating (thermal or electrical insulating?) materials that withstand cycling to liquid N2 temperatures.
Your question imples that shape must be maintained. How much load must it carry?
You say you need spacers; if the system is changing temperature, the gap which the spacer is supposed to fill is probably going to change dimensions.
Does the spacer cause the dimension change or is it responsible for it?
How mechanically compliant is the space to be filled?
Like is it more like an electircal insulator in a loose stack of washers or an O-Ring in a clamped steel assembly?
Dave
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