Synthesis of near-spherical BN powders by templated carbothermal reduction and nitridation

Boron nitride (BN) powders with near-spherical particles of more than 10 µm were synthesized by templated carbothermal reduction and nitridation. The effects of processing factors, such as raw material mixing methods, C/B₂O₃ molar ratios, and carbon templates, were systematically studied, and the reaction mechanism was discussed. The experimental results showed that the integrity and morphology of the carbon templates was usually destroyed during ball milling or grinding, but preserved during magnetic stirring. The morphology of synthesized BN particles depended on the C/B₂O₃ molar ratio in starting reactant mixtures and gradually changed from sheet-like to near-spherical shape with decreasing C/B₂O₃ molar ratio. The morphology and size of synthesized BN particles agreed with that of the carbon templates, which means that the morphology and size of synthesized BN particles can be tailored by controlling that of the carbon template. The BN near-spherical particles synthesized in this work may be used as thermally conductive fillers for electronic packaging.