Synthesis of sub-micro sized high purity zirconium diboride powder through carbothermal and borothermal reduction method

Abstract

Sub-micro sized zirconium diboride (ZrB2) powders were successfully prepared via the boro/carbothermal reduction method using zirconium oxide and boron carbide as the primary raw materials. The prepared mixtures were thermally reacted at 1250 degrees C for 1 h. The optimized composition range containing the lowest oxide and carbide impurity, which was 0.14% of oxygen and 0.3% of carbon contents, was determined using crystallographic and elemental analysis. The particle size was reduced from 5 pm to 245 nm by the addition of B4C as a reductant within a composition range that maintained the highest purity. The morphology changed from faceted to angular hexagonal bar-like with a simultaneous growth in particle size. Changes in the particle structure were a result of the existing liquid B2O3 phase during the reaction. The 245-nm particles contained 12.1% oxygen content and 16.2% oxygen content for the 5-mu m particle in the circumstance in which limited oxides could be produced.