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 Xray 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 mu m at 1093 K. The obtained ReB2 powder can scratch the surface of polycrystalline synthetic diamonds (H-K = 7000 kg/mm(2)). The obtained powders will be useful for developing of new superhard alloys and pigments.