PREPARATION OF ZRN FINE POWDERS FROM ZRO2 BY REDUCTION WITH MG AND THEIR RECOVERY

Preparation conditions of ZrN fine powders from ZrO2 by the thermite method using Mg under a nitrogen flow (200 cm3/min) have been investigated. Operation conditions for acid washing and the electrophoretic deposition of ZrN to obtain well defined ZrN powders have also been studied. The Mg/ZrO2 molar ratio was kept constant at 5 but the charge varied from 1 to 7 g. No unreacted ZrO2 was observed in the products. ZrN fine powders of single phase have been synthesized at 600-degrees-800-degrees-C in a relatively short time. On the other hand, about 0.5-0.8 wt% of Mg remained at the ZrN particles after acid washing with 1-2 M HNO3. The amount of Mg was not affected by synthetic temperature. It was found that the electrophoretic deposition method is a convenient and effective means for the recovery of ZrN fine powders from the products suspended in ethanol after acid washing.