Preparation of zirconium-based ceramic and composite fine-grained powders

Zirconium-based ceramics and composites such as ZrC, ZrB2, ZrC-SiC, ZrB2-SiC-ZrC, and ZrB2-SiC-ZrC-ZrSi were synthesized in fine powder form via combustion synthesis (CS) using ZrSiO4, Mg, C, B, and NaCl as raw materials. Temperature distributions in the combustion wave were measured by thermocouples and used to estimate the combustion temperature and wave propagation velocity. The influence of the NaCl mole fraction on the combustion parameters, phase composition, and particle size of the composite powders was investigated. The experimental results revealed that the combustion temperature and particle size of the composites have a stable decreasing tendency with increase in the NaCl mole fraction in the starting mixture. It was found that near the combustion limit (1.5 mol NaCl), the combustion temperature drops below 1500 degrees C and the particle size reaches the nanometer scale. (C) 2011 Elsevier Ltd. All rights reserved.