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I am new to chemistry. I am looking for a gas that would de-oxidise aluminium. Which gases would work for that and at what temperature?

Details: I need to sinter aluminium powder. But because the top layer of aluminium is oxidized when exposed to the atmosphere, I need to remove the oxide film before the sintering would work.

Thanks so much,

Sergey

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Since Al2O3 is very stable, powerful acids such as HF and chromic acid are used to remove the oxide surface. Since you're working with fine particles and wish to use a gas, rather than liquid, you'll need to consider what will become of the removed oxides. Gaseous HF would leave fluorides behind. Perhaps atomic hydrogen might work, but you'd have to remove the resultant water before the Al reoxidizes.

It is easier to prepare powdered aluminum in an inert atmosphere from bulk aluminum. There are a number of sites showing how to grind aluminum using anything from a file to a coffee grinder; you'd need to adapt this to run in argon, perhaps with a glove-box.

Sintering might be difficult, since Al is so soft that pore spaces would close.

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  • $\begingroup$ Thanks so much for the answer. At what temperature H would take O from Al? Would other gases, like N or CO work? If yes, at what temperature? Should I use aluminum alloy instead of pure aluminum? Thanks a lot! $\endgroup$ – Sergey Feb 28 '15 at 14:54
  • $\begingroup$ It would be easier to produce your own unoxidized Al powder than to remove the surface. The mention of atomic hydrogen was hypothetical rather than practical... you'd need to generate a hydrogen plasma, perhaps with RF, at low pressure and temperature so as not to melt the aluminum powder. As for sintering, an alloy would be better than pure Al, as it could be harder and resist compaction (I assume you want to sinter to a frit, rather than merely solidify). $\endgroup$ – DrMoishe Pippik Mar 1 '15 at 0:00
  • $\begingroup$ I do want it to merely solidify, and compaction is desirable for my application. Hydrogen plasma sounds too complicated, so I'll look into production of my own unoxidized Al powder. Thanks a lot! $\endgroup$ – Sergey Mar 1 '15 at 5:42
  • $\begingroup$ Sorry for misunderstanding the intent... you might be interested in this process of Al sintering, similar to injection molding of plastics: aluminiumindustry.org/en/… . $\endgroup$ – DrMoishe Pippik Mar 1 '15 at 17:35
  • $\begingroup$ Yes, it's somewhat similar, but they use a binder. Unfortunately they don't tell how they do the deoxidation. $\endgroup$ – Sergey Mar 1 '15 at 21:04

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