Cryogenic Materials (Non-Metallic)
Cryogenic Materials (Non-Metallic)
(OP)
Hi,
What non metallic material is best based on the following (in order of importance):
1) Has a CTE as close as possible to stainless
2) Relative isentropic contraction properties
3) Hold a piston/bore O-ring seal with stainless separating vacuum space from helium space (140 psia and 200 K)
4) Low thermal conductivity (less than 1 W/mK)
Thank You.
What non metallic material is best based on the following (in order of importance):
1) Has a CTE as close as possible to stainless
2) Relative isentropic contraction properties
3) Hold a piston/bore O-ring seal with stainless separating vacuum space from helium space (140 psia and 200 K)
4) Low thermal conductivity (less than 1 W/mK)
Thank You.





RE: Cryogenic Materials (Non-Metallic)
This didn't make any sense to me. Maybe you could explain a bit better.
Regardless, you might consider G10. Its CTE is about as close to Stainless as you're going to get with a material that has a thermal conductivity of less than 1 W/mK. Physical properties aren't perfectly isentropic, but they're close. If you'd like, I can post some graphs of properties.
RE: Cryogenic Materials (Non-Metallic)
torlon, peek or ultem plastics
RE: Cryogenic Materials (Non-Metallic)
I was thinking of using G-10 NT from Spaulding Composites, so it's good to hear that I'm on the right track.
As far as #3 goes... I need to hold a helium tight seal with an o-ring touching the G-10. Spaulding says that they can get the surface finish down to 40 RMA, so with silicone o-rings they have helid vacuums agsinst the G-10 down to militorr values.
I would very much like to see whatever CTE/THERMCOND graphs you have relative to G-10 and other cryo materials.
Thank You
RE: Cryogenic Materials (Non-Metallic)
torlon looks promising.... do you have any information on the behavior of this material at cryo temperatures?
RE: Cryogenic Materials (Non-Metallic)
could a FEP teflon seal be incorporated? it can be used at liquid helium temp and at least modest pressures
RE: Cryogenic Materials (Non-Metallic)
I think it can be used in this app... I'm looking into FEP Teflon now. Thanks.
RE: Cryogenic Materials (Non-Metallic)
http://w
Their design guide has some information about cryogenic properties:
ht
Drake Plastics is here:
http://www.drakeplastics.com/
I've done some minor testing with it. I dunked a small cylindrical part in liquid nitrogen, put it on a concrete floor and tried to smash it with a hammer. It held up extremely well, though other materials did also including PEEK.
RE: Cryogenic Materials (Non-Metallic)
Thanks for the info. I'm going to call Drake this week to make some final decisions.
RE: Cryogenic Materials (Non-Metallic)
Cryogenic Material Properties Database
ht
RE: Cryogenic Materials (Non-Metallic)
I've read this paper a dozen times. It's a great reference! What I'm looking for is the same level of detail with non-metallics other than the ones covered in the NIST paper. The nist paper covers, polyamide, teflon, and G-10. The most suitable material among those three is G-10. But torlon has the most suitable CTE... I just wish I had the CTE as a function of temp as in the NIST documentation.
In the end I'll probably make this part out of 3 different materials and test.
Thanks.
RE: Cryogenic Materials (Non-Metallic)
Volume 1 is all metals (aluminim, SS, ... )
http://ww
Volume 2 has the plastics in it.
http://ww
RE: Cryogenic Materials (Non-Metallic)
Huge thank you for your last post!!
RE: Cryogenic Materials (Non-Metallic)
B
RE: Cryogenic Materials (Non-Metallic)
Interesting. Would you say that any glass filled material will abraid o-rings?