Hello all, can anyone suggest me an insulating material which should act as electrical and thermal insulator at the temperatures 1200°C or above and should not react with oxygen.
Thermal insulation properties at this temperature are probably dominantly based on structure. Any material that has high porosity and, ideally, a physical structure with minimal connectivity in the direction of heat transfer, should be a good insulator. These structural properties will also minimize electrical conductivity, although in addition the material should have low electrical conductivity when it has no porosity. Some good candidates that are robust to oxygen exposure include highly porous alumina, mullite, zirconia, and silica. I would think most covalently bonded inorganics would do well.
Dear Larry L. Baxter,
Thank you so much for your valuable information.
Can you suggest me some sources where I can get complete material properties of the given materials and all ceramic materials.
Micas are also very good thermal and electrical insulators at high temperatures. I am not sure if they retain these properties at such a high T (1200 oC).
Maybe, zirconia oxide (ZrO2) is a relatively good choice to the electrical and thermal insulator when the temperature is 1200°C or above. For thermal insulation, it should be no problem. I did not measure the electrical insulator of ZrO2 and not sure it is perfect or not.
Dear Lidong Dai,
Thank you for the information.
But the problem with zirconia oxide is at 1200°C it will become semiconductor.
The electrical resistivity drops drastically.
I need some other material which can maintain its electrical and thermal properties at this temperatures.
Dear all,
Effectively the answers are going more and more on the right way. Indeed zirconia can have a drop down of electrical insulation properties in this range of temperatures, more effectively if the oxide is not stoichiometric. PLease consider MgO that is used both as high temperature insulator in shielded resistance wire and as a component of bricks in high temperature and mass melting special alloys to protect the crucible (i.e. High Frequency melting) for both characteristics thermal insulator and electrical insulator. There are variants of cements used for and based of magnesia.
Since these purposes this material is available at industry scale.
See for more information on characteristics:
http://w3.pppl.gov/~neumeyer/ITER_IVC/References/1981_Wilson_BICC.pdf
Kind regards
Daniel
You can do a quick search using www.matweb.com. Use the property search to filter.
Kind regards,
Carlos Almeida
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