Reaction Processes and Characterization of ZrB2 Powder Prepared by Boro/Carbothermal Reduction of ZrO2 in Vacuum

The present work was concentrated mainly on the reaction processes of boro/carbothermal reduction (BCTR) of ZrO2 with B4C and carbon in vacuum, and characterization of morphology and sinterability of the obtained ZrB2 powder. Combining the thermodynamic calculations, X-ray diffraction results, and the trend of furnace pressure with temperature during synthesis, a detailed explanation of the reaction processes of BCTR was developed. Most of the ZrB2 particles obtained at 1650 degrees C presented a nearly spherical morphology, whereas those synthesized at 1750 degrees C showed a nearly columnar morphology with an increased size. Compared with the powder synthesized at 1750 degrees C as well as the commercially additive-free powder used in the reported work, the ZrB2 powder synthesized at 1650 degrees C showed a better sinterability due to its smaller particle size and lower oxygen content.