🚀 go-pugleaf

Regarding using nitrogen to pressurize molten aluminum

> Henry Spencer writes:
>
> There's no significant amount of nitrogen on the Moon unless there are
> frozen polar volatiles.  You can recover a very little bit from the
> regolith, if you're willing to process a lot of regolith.
>
> A note of caution:  you're assuming that nitrogen is an inert gas.  This
> isn't necessarily true when hot metals are involved.  I'm not sure about
> aluminum, but I know titanium will burn fiercely in nitrogen (in fact,
> the ash from titanium burning in air is about 80% titanium nitride).
> Without an ignition source, the combination might be stable enough.



        Molten aluminum is stable enough in air which is 80% nitrogen.
However, there may be some formation of protective oxide layers, and the
pressures involved are nowhere near the pressures needed for rockets.
Anyway, the point is probably moot if the pressurizing gas has to be imported
from the earth - in this case helium would have a fraction of the mass and be
a truly inert gas for use in pressurization.

--
Bruce Dunn    Vancouver, Canada   Bruce_Dunn@mindlink.bc.ca