Preparation of hafnium powder by calciothermic reduction of HfO2 in molten chloride bath

Hafnium oxide was reduced to metal by using Ca dissolved in the molten CaCl2–NaCl mixture. The investigations were carried out at a temperature lower than the melting point of Ca which ensured minimum reductant loss through evaporation .The oxygen content in the produced metal was lowered under 1000 ppm level and it was highly depended on the amount of Ca and the amount of salt. Various salt compositions have been studied in order to select the best composition for the reduction process and it was found that the system containing 30 mol% NaCl could produced hafnium metal with 960 ppm oxygen.