Aluminium+copper alloy vacuum outgassing

  • #1
Alberto Spain
3
0
TL;DR Summary
Can I use aluminium 2007 for high vacuum projects it since contains copper?
Hello.

I need to make a part for a oil difussion vacuum pump and I want to use aluminium 2007 allow. This allow contains around 4% of copper and 1,5% of lead. I don´t know if those metals can outgass during the vacuum process. That vacuum pump is supposed to reach around 5 x 10 -6 mbar or 5 x 10 -4 Pa

Thank you

best regards
 
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  • #2
That aluminium surface will have an oxide layer, plus some diffused moisture...

You may have to tackle like a thermionic valve and slowly bake-out, then 'getter'...

IIRC, you may even need to use an electron beam or cold-discharge to 'scrub' surface. Perhaps research how space-telescope frames etc are 'cleaned up' to prevent out-gassing tainting the sensors...
 
  • #3
A diffusion pump is (basically) an oil boiler. I would be more worried about the managing the headache of large dimension changes (with temperature) that will occur with aluminum - Those will last forever (or until something breaks). Heating/Cooling a diffusion pump is a noisy affair (even with much more thermally stable materials). All off-gassing stops eventually (explained this to my wife last weekend - the dog vomited in her new car...)
 
  • #4
Thanks for your answers. I hacve to use aluminium. I don´t have the skills nor the equipment to machine stainless steel.

But since I´m going to use aluminium, is htere any problem using 2007 instead 6061 or 6082. I went for the 2007 because it is easy to machine.

And about the changing in dimensions, the aluminium is only for the "jets", the main body will be stainless steel
 

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