I would like to obtain Si particles from magnesiothermic reduction of SiO2 particles. I've see in some papers that they put SiO2 and Mg in shielded stainless steel tubes and then in tube furnace under inert gas. Is it possible to do it by placing the powders in an alumina crucible and then straight away in the ceramic tube furnace under inert gas or it is mandatory to use the stainless steal tube?
Dear George,
as far as I know Mg powder is very sensitive to the presence of humidity ( it can catch fire). Probably this is the reason why a sealed stainless steel tube is needed and I suppose that they prepare their mixture of powders in a glove box, in an inert (probably N2 atmosphere). We have first to check the Mg powder particle size distribution. The lower the most sensitive to reaction with humidity. Please tell me the conditions inside SS Tube, is it vacuum or atmospheric pressure?
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Hello George!!
In the litrature they report various methodes and I'm not sure which is the right and safer one. They put the materials in the SS tube inside a glovebox under Ar and then they close the SS tube and put it in a tube furnace with Ar flow. In another paper they don't report any SS tube.They just mix SiO2 and Mg and put in in tube furnace and heat it.
How to remove NaCl from from the gel like Si particles that are formed after magnetio-reduction. I came across many referances that have added NaCl in this process as heat scavengers. But after the reduction process, I got a mixture of Silicon particles and NaCl in the form of gel.
Dear All,
Interesting discussion. The primary reason alumina may not be the best option is that Mg can reduce Alumina to Al and MgO, this may contaminate your sample, disturb your stoichiometry and potentially damage your crucible.
Typically steel is used. Sealed or open reactors can be used but the reactants must be under a protective atmosphere, otherwise you will oxidize all your Mg to MgO. Whether this be a sealed reactor with atmosphere or an open reactor in a tube furnace.
For any further information myself and colleges have published this recent review on the magnesiothermic reduction process and are active in this area.
https://pubs.rsc.org/en/content/articlepdf/2018/ta/c8ta06370b
Richa is the NaCl not removed during washing with HCl?
Jake Entwistle Read your review. Very interesting. Thank you for writing it. However, the only detail missing in the review was about the choice of containers, which this gentleman is also asking about and for which, I landed here. Is there any other way to do that other than SS tubes. You wrote in your review that the temperature may rise to above 1300 degrees, will it not break the tube furnace? Also, what about the ratio of heat scavenger i.e. NaCl, to the sample/Mg? It would be great, if you could put some light on that. We can try, but just being concerned about the safety. Thank you very much!
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