Mechanochemical synthesis and consolidation of nanostructured cerium hexaboride

This study reports on the mechanochemical synthesis (MCS) and consolidation of nanostructured CeB₆ powders of high purity. CeB₆ powders were prepared via MCS by milling CeO₂, B₂O₃ and Mg powders in a high-energy ball mill for different milling times. The effects of milling time on the formation, microstructure and thermal behaviour of the synthesized powders were investigated and the optimum MCS duration was determined. Purified powders were obtained after HCl leaching by removing MgO by-product. The prepared powders were characterized by a number of techniques including X-ray diffraction, stereomicroscopy, scanning and transmission electron microscopy coupled with energy dispersive spectrometry, differential scanning calorimetry, atomic absorption spectrometry, particle size analysis, surface area analysis and vibrating sample magnetometry. The high-purity CeB₆ powders having an average particle size of 86 nm were consolidated by cold-pressing followed by pressureless sintering at 1700 °C for 5 h. The bulk CeB₆ specimen was investigated for its microstructure, density, electrical resistivity, surface roughness and some mechanical properties (microhardness and wear behaviour). The relative density, electrical resistivity, microhardness and wear rate of the bulk CeB₆ were determined as 95.2% TD, 57.50 µΩ·cm, 11.65 GPa and 1.46 × 10⁻⁴ mm³/N·m, respectively.