Permeation of helium through metals

[dcopps]

I am a librarian seeking data on the permeation of helium through metals. We know He does not permeate through bulk metals, but we are looking at depositing thin films of metal and it needs to seal well for He. Thank you.

 

[btrueblood]

"We know He does not permeate through bulk metals"

Or at least not at readily measureable rates.

"but we are looking at depositing thin films of metal and it needs to seal well for He."

Different question - the permeation rate through a thin deposit will depend on the degree of porosity of the deposit. Generally, vapor deposits (done in vacuum) give lower permeation rates, but that was 15+ years ago when I was looking at it. There are lots more deposition technologies available today.

 

[EdStainless]

The NASA data bases are where you go for this info.
They have done work on He permeation through metalized plastic films.

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Plymouth Tube

 

[IRstuff]

Just from personal experience, metallized plastic could be metallized mylar, i.e., high-end balloons, which do leak at a noticeable rate, so whatever you're depositing needs to be thicker than that.

TTFN
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[tbuelna]

He is used for detecting leaks precisely because it is very hard to contain. As for whether your deposit of a thin metal film is free from He leakage, that would depend on the specifics of your metal thin film application.