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[RaniellaBianca]

Can I use helium as a substitute inert atmosphere for the synthesis of Cr2AlC powder? 

[samayaraj]

In process industries, generally nitrogen is used for blanketing. In certain conditions, nitrogen became reactive and hence we need an inert gas. So we go for argon. Since it is dead cheap compared to other inert gas such as helium etc. Also argon is heavier (atomic weight 40) which displaces other lighter molecules easily and does the job perfectly.

 

Helium can also be used as inert gas, but it will be a very costly operation. In natural gas small quantity of helium will be present and this will be separated under very low temperature (near abs. zero). Only small quantities can be recovered and hence they are very very costly. We use helium as inert gas during special case where you need good heat transfer properties. Also helium being very light in weight, it will diffuse very easily and hence you cannot maintain the pressure constantly. You need a perfectly sealed container to minimize the leak.