What types of bearing, and what speeds and loads do you need them to carry?

Simple low speed (and light) thrust bearings can be made from slabs of PTFE and stainless steel - and they'll work down to far lower temperatures than 100K.

Thank you for your answer. I searched in the internet and found some manufacturers. Unfortunately i coulndt find product catalogs or something else, which contain the sizes of the bearings. Are this bearing custom built?

Michael,

It depends on the type of bearing - rotating thrust bearings or something else?

And knowing the loads would be good too.

I need bearings with Fax = 0.5 kN and Fra = 2 kN. The Bearings will be loaded thrugh rotation (radial loadings) and bending moment through radial forces. (about 1kN)

Okay.

That's not too high.

I'd start with a some inherently low friction bearings (cages of PEEK, polyimide, PTFE, etc.) and then simply degrease them (repeated soaks with warm isopropyl). A little dry lubricant might help (powdered PTFE, graphite, etc.)

And there *are* a few cryogenic dry lubricants that you may want to try.

https://www.graphalloy.com/html/articles/maintaining_lubricity_cryogenic_temps.html

Thank you!

You could always get your own bearings made from PTFE bar or sheet depending on the form. They can be very simple.