Need ideas for high temperature sealed container.

[Latsabb]

For my bachelor project, I am in need of an air tight (or very, very near air tight) container, which can withstand 750 C. My original thought was to have a steel container with a lid and gasket, but I was unable to find any gaskets that got anywhere near that.

Does anyone know of a gasket material that will withstand that? Or have another idea as to how I can make an air tight container for this temperature? It will be sustained, likely 1-2 hours at a time, and will be about the size of a toaster. (just large enough for a crucible and some electrodes.

Thank you in advance for any input!

 

[Vagn]

Why does the box need to be airtight? Would you be able to use something like a graphite box inside a glove box, or do you need a vacuum?

 

[Latsabb]

It needs to be air tight as we will be monitoring a reaction inside, and measuring gas concentrations. So if it isn't tight, there will be gas exchange with the atmosphere, which will mess up all the measurements.

 

[phyzguy]

Usually people use metal-metal seals in cases like this. They are like elastomeric O-rings, but are made out of a soft metal that crushes when you seal the container. http://www.techneticsgroup.com/products/sealing-solutions/metal-seals/ are some examples.

 

[Latsabb]

Thanks, I will check into that. I was afraid that I would need to buy in a ton of the high temperature sealants, and then replace it after every experiment.

 

[gjonesy]

I'd look into High heat Furnace cement or Kiln cement, those would be about the only things commercially available that would be anywhere close to meeting 750 c requirement. Fire proof plaster may be another or good old fashion natural clay. I know these things work on metal forges, whether or not if its (air tight), that I do not know.

Note after you seal this container you will have to break it open. So you will need a good supply of it if the project has to be repeatable. Good luck

 

[gjonesy]

Usually people use metal-metal seals in cases like this. They are like elastomeric O-rings, but are made out of a soft metal that crushes when you seal the container. http://www.techneticsgroup.com/products/sealing-solutions/metal-seals/ are some examples.

Metal may work, but if its a custom made box you will probably have to custom make the metal gasket, and the best would be probably 1/4 inch brass then the next would be 1/4 copper. Still not sure about how air tight you could make it.

copper melting point 1085 c, brass melting point 930 c

 

[phyzguy]

Metal may work, but if its a custom made box you will probably have to custom make the metal gasket, and the best would be probably 1/4 inch brass then the next would be 1/4 copper. Still not sure about how air tight you could make it.

I once worked on a vacuum system that had two stainless steel hemispheres with a metal seal between them made of a ring of aluminum wire which was crushed by clamps as you sealed the chamber. It maintained a vacuum of 10^-8 torr, so metal seals can be quite airtight. You had to discard the aluminum seal each time you opened the chamber.

 

[gjonesy]

metal seal between them made of a ring of aluminum wire

Yeah aluminum would be probably the softest but it melts around 660 c so it wouldn't be a good choice for this

 

[Latsabb]

It will be a custom container, but since it isn't ordered yet, it should not be a problem to have it made to specs for metal seals. The plan was to use Hastelloy, and from what I have been seeing, the metal seals made great seals on steel.

 

[russ_watters]

You say air tight. How air tight? Will it be pressurized significantly?

 

[JBA]

If you can use a cylindrical container for your testing, take a look at the below site.

http://www.lamons.com/public/pdf/lit_reference/Lamons_Purely_High_Temperature.pdf

 

[SteamKing]

The gaskets used in IC engines between the cylinder block and cylinder heads are usually all metal.

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The metal in the gasket is thin enough to be stamped out of a plain sheet of material. You do have to design the container with sufficient clamping force so that the gasket will seal.

 

[Latsabb]

There should be no significant pressure, as it will be heated with free flowing air, and then sealed once the crucible is added. Then there will be an input and output line for reaction gas flow.