metalresearcher - 21-11-2015 at 03:50
This morning I did an experiment by putting 1 gram of aluminum metal in a cavity in a concrete tile cutout and arced it with a 63A DC arc using carbon
rods, to see whether I can really bring Al to its boiling point of 2500 C.
That indeed happened after a few seconds and the metal started to burn as well (bright white sparks escaping). After shutting it down and allowing it
to cool, I inspected it (2:48 on the clip) and saw beneath the very hard and brittle stuff (probably crystallized Al2O3 corundum) gray crystalline
chunks which resemble silicon. I think probably the SiO2 which is a main ingredient of concrete, is reduced by the Al.
Is that true ?
http://www.metallab.net/jwplayer/video.php?f=/clips/Boiling%...
phlogiston - 21-11-2015 at 15:12
A very simple test you could do is to add hydrochloric acid. Residual aluminium and aluminium oxide should dissolve. Silicon will not.
Texium - 21-11-2015 at 17:49
Then again, that aluminum oxide that is most certainly calcined from the high heat may not dissolve very well. But it should be easy enough to
distinguish between it and the silicon.
PHILOU Zrealone - 19-12-2015 at 12:09
Following the hereunder datas:
Si density = 2,329
Al density = 2,699
SiO2 density = 2,2
Al2O3 density = 3,95-4,05
Al2SiO5 density = 3,13-3,65 depending on cristalline form
CaSiO3 density = 2,0 (cement is mainly CaSiO3 (thus CaO and SiO2))
Si should float on most of the compounds involved in your experiment and especially the Aluminum based ones!
So it is possible that you have something else...
Al silicide? Al4Si3
Aluminium silicium alloy?
Down here a picture of Silicum I bought at a gemstones and mineral fair for about 12€, it has a metallic shine and is quite light, a bit like
charcoal for barbecue, but it is quite hard in comparison.
