High temperature electrical insolator that repels carbon deposits

[Quince]

Is there any material/s that will handle CVI furnace temperatures (1250 C) and will either repel carbon deposits or react with it to create a compound that is not electric conductive? Trying to contain power to the heating element without shorting it to the base/ground through heating element supports.

 

[Tom.G]

Not offhand. But can you but a shroud around most of the support length to shadow it? Of course if the Carbon is from a decomposing flowing gas this may not help much. A labyrinth seal at the open end of the shroud may be the next step.

(Here is an attempted sketch but it may not render correctly)

               ___________ shroud
               | 
element        |______________ to wall
suppoort-------|
               |__________

Cheers,
Tom

 

[Nik_2213]

IIRC, HV & EHV pylon, transformer & switch-gear 'stand-offs' are corrugated to increase path length, but may also have a surface finish / treatment proven to repel muck.

Could be worth a look...

FWIW, even such do need jet-wash cleaning from time to time: My wife got stuck in a shopping centre lift when contract cleaners mistakenly sprayed the 'live' set at local grid station, tripped half the city...

 

[Quince]

Tom, the deposit IS from gas and about .003" (.076 mm) in a single 2 day run. I have nitrogen flowing to protect, but the main box will always bleed some gas. Hard to seal at that temperature without sinking the boat. Rebuilding the supports is a long, expensive and painful process. Finding a solution will be quite elegant and beneficial, maybe, to other applications.

Nik, I’ll have to find out what IIRC, HV, EHV and FWIW stand for.

 

[Nik_2213]

Oops.
'If I Remember Correctly'
'high voltage'
'Extremely high voltage'
'for what its worth...'
:-)

 

[Tom.G]

Tom, the deposit IS from gas and about .003" (.076 mm) in a single 2 day run. I have nitrogen flowing to protect, but the main box will always bleed some gas. Hard to seal at that temperature without sinking the boat. Rebuilding the supports is a long, expensive and painful process. Finding a solution will be quite elegant and beneficial, maybe, to other applications.

Understood. Can you plumb the Nitrogen so it is aimed at the supports? Probably not cheap but maybe the cheapest.

As a last-resort possibility, consider the shroud approach with the Nitrogen delivered inside the shroud for a continuous inert atmosphere.

Interesting problem. please keep us updated.

Cheers,
Tom