Uncle Al wrote:
Front Office wrote:
Yesterday, a friend and I tried to liberate some silicon
from its oxide.
It doesn't want to go. If you get it out, it wants to combine with
the stuff that got it out. Also note that silicon expands when it
freezes.
We pulverized a piece of milk quartz, ~50 grams, which
we mixed it with ~30 grams of fine aluminum dust. We put
~20 grams of the mixture into a graphite container,
then exposed it to an electric arc from an arc welder.
Ride 'em cowboy! Silicon (or sand) + graphite --> carburundum Look
up how it is manufactured commerically.
I had expected to find a nodule of silicon in the bottom
of the graphite container, but it didn't happen - which
makes sense, given that silicon has such a low specific
gravity. What we got was maybe mostly silicon, but I
don't know.
http://sti.srs.gov/fulltext/ms9900751/ms99007514.gif
Aluminum silicide is well known.
Questions:
Are silicon and aluminum oxide miscible with one another,
or can one dissolve into the other?
Phase diagram, above. Look up others.
Is there a flux that might separate aluminum oxide from
silicon?
Look up how silicon is manufactured. Would they do it that way if a
Goldschmidt reduction gave good results?
What are some simple tests for elemental silicon, simple
in the sense of being able to be done with stuff that
can be got at a hardware store?
Drop the blob in strong acid (not HF). Silicon doesn't care.
Al4Si3 + 12HCl -> 3SiH4(g) + 4AlCl3 (followed by hydration and
hydrolysis)
Silane smells awful and is pyrophoric. Aluminum would only gives you
hydrogen. Aluminum carbide gives you methane. If you actually got
silicon it is more likely that you got carborundum as the end product.
As always, Uncle Al, much thanks for your response.
I will study up on all this . . .
Bob
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