Preparation of ZrB2 and ZrB2-SiC powders in a single step reduction of zircon (ZrSiO4) with B4C

The reduction of zircon (ZrSiO4) with C and B4C results in the formation of impurity phases like ZrO2, ZrC, ZrSi, SiO2, SiC and borosilicate. Synthesis of pure ZrB2 by eliminating SiO2 in ZrSiO4 in a single step reduction with B4C has been studied. Without adding free carbon, zircon was reduced with B4C in different weight ratios (ZrSiO4/B4C=1.6/2.5/3.3) at different temperatures between 1300 °C and 1600 °C in argon. The ratio of ZrSiO4/B4C and reaction temperature were optimized to produce a single phase ZrB2 free from impurity phases. Addition of carbon or B4C to an optimized mixture of (ZrSiO4/B4C=3.3) has resulted in the formation of (ZrB2-SiC) composite powder. Composite powders of (ZrB2-SiC) and (ZrB2-SiC-B4C) were formed by increasing the B4C content to ZrSiO4/B4C=2.5 and 1.6 respectively.