metalresearcher - 26-3-2020 at 00:08
I tried this experiment in a 2:1 MnO2 + Al stoichiometric mixture and it indeed reacted quickly. but unlike an Fe2O3 thermite, which yields frozen
droplets of real iron metal, this yields a frozen brittle brown substance (a mixture of lower Mn oxides ?).
The MnO2 is lab grade, not from old alkaline batteries.
The bp of Mn is 2060 C close to the melting point of Al2O3 (2020 C) which may vaporize the Mn metal ?
Is there a way to isolate Mn metal from thermite ?
j_sum1 - 26-3-2020 at 05:03
You should check out The Gayest Person on Youtube.
He uses fluxes to control temperature and fluidity. He also indicates how he calculates flux proportions. He ends up with rather pretty ingots at the
end.
rockyit98 - 26-3-2020 at 06:23
even pure Mn is brittle. i think what you have is Mn+Al mix metal alloy. even SiO2 better than no flux .aluminium silicates melt around 1200 to 1700C
depends on SiO2 content.i have made soda-lime glass powder with broken glass in a ball mill that will do too.much lower melting point.try Mn2O3 or MnO
instead of MnO2 as it tends to decompose into Mn2O3 and O2 anyway .maybe mix up so as much more MnO2 will make higher temperature.
[Edited on 26-3-2020 by rockyit98]
metalresearcher - 26-3-2020 at 12:08
I tried it again. Now I used 1.5g Al powder and 3g MnO2 and 1.5g SiO2 as moderator. The reaction ran much slower and after cooling I digged in the
result and it looked more 'metal like', see the end of the video.
https://www.metallab.net/jwplayer/video.php?v=L2NsaXBzL01hbm...
a_bab - 8-4-2020 at 22:37
MnO2 is not good for your goal because the reaction is too violent and most of the products will simply be vaporized. Moreover, the Al needs to be
granular (atomized) - those fine Al powders are too fast-reacting.
If you want the thermite route (as electrolysis is one known to work properly) here you go:
You need Mn3O4, obtainable from MnO2 via calcination at 1000 - 1100 degrees C till a constant weight is obtained, followed by a quick cooling of the
product (at 600 degrees C Mn2O3 tends to form).
Mn3O4 is a brown-black stable powder.
The reaction mixture is made of: 20.7g Mn3O4, 5.5g Al and 3.6g fresh CaO. This will react slowly, much like the iron thermite.
The slag can contain up to 20% looses from a manganese - aluminium compound.