Need ideas for sealing aluminum chamber at 350C

[DanTheMechE]

I'll try to keep the problem statement as short as possible.

Looking to seal aluminum chambers at 350C. This environment is too high for elastomer o-rings. Metal seals look nice but due to the high compression load, and the yield strength of aluminum at 350C, we're worried our chambers might yield.

The chambers have to be made out of 6061-T6. Due to the plasma and Flourine environment, we are limited by material choices.

Any ideas how I can solve this problem other than locally cooling the o-ring grooves? We were thinking maybe we can braze on a strip of a stronger material along the o-ring groove so that the metallic seals wont cause yielding but then we run into CTE mismatch issues.

 

[A8yssUK]

Could try mica or vermiculite seals if the seal is static.... graphite is a no go with the flourine and plasma..

Flexitallic's Thermiculite 866 or 866LS *may* stand up to the plasma/flourine and shouldn't require as much force as the metal seals.

 

[Compositepro]

At 350C you can no longer have T6 aluminum. High temperature vacuum and pressure chambers are insulated on the inside so the pressure envelope is not exposed to high temperatures.