Good thermal conductor but insulator

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SUMMARY

The discussion centers on identifying materials that are both good thermal conductors and electrical insulators at cryogenic temperatures around 4 K. Sapphire is noted for its thermal conductivity but is difficult to fabricate. BeO ceramic is mentioned as a potential candidate, though it requires careful processing due to toxicity concerns. Thermally conductive ceramics and plastics, such as those from Cool Polymers, are suggested as alternatives, along with hard anodized aluminum, which can prevent electrical conduction through its oxide layer. Boron Nitride is also proposed as a viable option.

PREREQUISITES
  • Understanding of thermal conductivity and electrical insulation properties
  • Familiarity with cryogenic temperatures and their effects on materials
  • Knowledge of materials processing techniques, particularly for ceramics
  • Awareness of safety protocols when handling toxic materials like BeO
NEXT STEPS
  • Research thermally conductive ceramics suitable for cryogenic applications
  • Investigate the properties and processing methods of Boron Nitride
  • Explore the use of thermally conductive plastics from Cool Polymers
  • Learn about the fabrication techniques for hard anodized aluminum
USEFUL FOR

This discussion is beneficial for materials scientists, engineers working with cryogenic systems, and anyone involved in the fabrication of thermal management solutions in low-temperature environments.

csopi
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Hi,

Does anybody know a material which is a good thermal conductor and an insulator at the same time (at temperatures around 4 K) and is "easy" to fabricate? For e.g. sapphire fulfils the first two requirements, but is extrmely hard.
 
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First through was diamond, but 'easy' to fabricate rules that out. Second thought is BeO ceramic, but must be processed very carefully to prevent Be poisoning. You may want to research thermally conductive ceramics - there may be some that are not dangerous to process. There are some thermally conductive plastics, best to contact www.coolpolymers.com
 
Thank you very much for your help, I'll look into the hints!
 
You might also consider simple hard anodized aluminum. The anodized layers should give you a thick enough oxide to prevent any electrical conduction. Of course, anything contacting it should not be able to break through this oxide layer.
 
Good idea, but unfortunatelly this won't solve my problem. I'll use it as a sample holder at 4 K, and it'll be subjected to AC magnetic fields. The aim is to get rid of the eddy currents and for this I need the bulk to be an insulator as well.
 
Have you considered Boron Nitride?
 

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