Carbothermic reduction of zircon under reduced pressure

Abstract

Carbothermic reduction of zircon, involving volatilization of silica content as SiO(g) under vacuum, has been investigated for the preparation of monoclinic zirconium dioxide (ZrO2), stabilized (cubic) ZrO 2 and zirconium carbide (ZrC). Process variables, such as zircon-to-carbon ratio, reaction temperature, soaking period etc., have been studied to optimize the process conditions. High purity and finely powdered (25 μm) monoclinic ZrO2 powder, containing less than 0.5 mass% silica, could be obtained by heating a mixture of zircon and carbon at 1773K under vacuum. The other two products, namely, stabilized ZrO2 and ZrC could also be prepared by adding calcium oxide (CaO) stabilizer to the zircon and carbon mixture or by carrying out the reaction in the presence of 4 mols of carbon per mol of zircon.