Feasibility of using Flexible Graphite (Grafoil ) gaskets in High Vacuum Sealing Applications

fully_automated_communism · May 21, 2020

Hello, I apologize in advance if this is the wrong place to ask this question, but I could not find any vacuum related forums. I am currently designing a thermal evaporation or PVD chamber that needs to reach a temperature of 600C and vacuum of 10^-7 torr. I originally planned on using a combination of Viton O-orings and Metal to Metal seals(CONFLAT)for the chamber but I am now considering using flexible graphite gaskets. The reasons for this are numerous, and have to due with the fact that graphite can withstand far greater temperatures and can seal micro cracks without the complexity of traditional metal to metal seals. My only issue is I have yet to find any literature regarding their use in vacuum systems and I have only seen information on it's use in aerospace and nuclear applications.

Am I just spit-balling here or is there some potential in this idea? Any suggestions in the right direction would be appreciated.

TugboatEng · May 21, 2020

I think gas permeability is going to be your greatest concern. We use Thermiculite 815 for our diesel engine exhaust systems. It absolutely blows graphite out of the water in terms of durability at elevated temperatures. They advertise a gas permeability of 0.06-0.17 mL/min by BS 7531 standard. I don't know if these are good numbers or not but there are many materials you can compare at their website.

https://flexitallic.com/us/product/thermiculite-815/

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Feasibility of using Flexible Graphite (Grafoil ) gaskets in High Vacuum Sealing Applications

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