Preparation of ZrB₂ Powders with Different Morphologies by Pressureless Reactions

Abstract

The ZrB2 powders with different morphology were prepared by pressureless reactions, using ZrO2, B2O3, B4C, and graphite as raw materials. Three kinds of chemical reaction system were employed. The ratio of raw materials and reaction temperature were adjusted to prepare ZrB2 powders of different morphology and particle size. The phase composition and purity of the as-prepared powders were analyzed by XRD, while the morphology and particle size were analyzed by SEM. The ZrB2 powders were purified by removing impurities at 600 °C in a muffle furnace in air atmosphere. The results showed that in the reaction systems of ZrO2-B2O3-C and ZrO2-B4C-C, the ZrB2 could be generated at 1500 °C. The morphology of the as-prepared ZrB2 powders were particles, rod-like or near spherical for ZrO2-B2O3-C system and particles for ZrO2-B4C-C system. In the reaction system of ZrO2, B2O3, B4C, and C with a mole ratio of 3:2:1:8, the ZrB2 powders with high purity could be produced at 1700 °C. The ZrB2 powder was near spherical. After heat treatment, the particle size and morphology changed to some extent.