Preparation of ultrafine boride powders by metallothermic reduction method

Ultrafine TiB₂, ZrB₂, and ReB₂ powders were prepared by the metallothermic reduction method using Mg. Obtained TiB₂, ZrB₂, and ReB₂ powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and scratch test. The morphology of the powders was a laminar hexagonal single crystal. The mean particle sizes of TiB₂ and ZrB₂ increased with increasing reaction temperature, and that of ReB₂ was 0.11 μm at 1093 K. The obtained ReB₂ powder can scratch the surface of polycrystalline synthetic diamonds (H_K = 7000 kg/mm²). The obtained powders will be useful for developing of new superhard alloys and pigments.