Reduction of SiO2 to Si by aluminum metal fog in NaCl–KCl–AlCl3 molten salt

Direct reduction from SiO2 to metallic Si by aluminum metal fog was attempted in NaCl–KCl molten salt. The aluminum metal fog was evolved by contact of liquid aluminum metal to Al(III) in the molten salt. The metal fog forms in the molten salt an atmosphere reductive enough to induce a reaction from SiO2 to Si. The immersion of SiO2 plate at the aluminum metal fog in the molten salt caused the color change of the plate, and the plate exhibited the darker color with time. From EPMA and XRD analysis, metallic crystallized Si was detected in the darkened area. From the color change with time, the reaction proceeding was discussed.