Molten Salt Hermetic Sealing without O-ring or Gasket

[hglund]

Hello All,

I have a unique engineering problem to propose to you all. I am working with the storage of some highly reactive molten salt at fairly high temperatures (<400C). While we are not working with a large amount of the salt, keeping it contained within a crucible/vessel is highly important and carries some real material constraints. Right now the design has two graphite/boron nitride plates with a pocket milled into them and a number of screws surrounding the pocket to tightly hold the two plates together and hopefully keep the salt in. BUT, I need a hermetic seal between the two plates and can't use any conventional O-rings or gaskets due to the reactive nature of the salts. I was thinking of trying something where I make a groove in one plate and a mating protrusion in the other and hope that is good enough. Does anyone know if this idea sounds feasible or if there are better routes I should explore? Thanks so much.

[Cragyon]

Tapered sealing surface machined accurate like a flare fitting and pipe end or a crushable gasket like used in vacuum systems.

[Hudson]

What are the problems with commercially available crucibles?

[hglund]

Thanks for the responses. I'm not sure how a tapered design could work with the types of experiments we need to perform on the molten salt. As for a crushable gasket, this is something I have thought about but have little experience in. I am working with two 1-2mm thin plates of graphite or boron nitride and I'm concerned adding a crushable gasket would just cause the plates to crack or break.

In response to you Hudson, a commercially available crucible has a few problems. I need the crucible to be hermetically sealed and not open topped, I need there to be sections in the crucible that are as thin as 200 microns and we are using very small quantities of the salt because it is truly that reactive with everything. I haven't seen an available crucible online that has such a small volume and is sealed and fits all these other requirements. If you have an example I'd love to see it.

Thanks for the responses I'll continue refining the idea