Preparation of refractory metal diboride powder by reducing refractory metal oxide with calcium hexaboride

This paper provides a new method for preparing refractory metal diboride by reducing refractory metal oxide with Calcium hexaboride (CaB 6 ), which is prepared using B 4 C and calcium as raw materials. For refractory metal powders (M = Ti, Zr, Hf, V, Nb, Ta, Cr) which are expensive and hard to be produced by a simple route, it is more cost-effective to directly use refractory metal oxide to prepare its boride. After reacting at 1473 K for 4 h, CaB 6 and refractory metal oxide could completely react to form MB 2 , CaO and B 2 O 3 . The single-phase product with the particle size of sub-micron was obtained after acidic leaching, filtration and drying. CaB 6 could be used as a universal reducing agent to prepare metal boride.