Preparation of Tungsten Boride Powder by High-Temperature Solid-State Reaction

Abstract:

Through a solid-state reaction, tungsten borides were synthesized from boron and tungsten powders under vacuum in a graphite element furnace. In particular, the effects of B/W mole ratio, the temperature and the holding time on the products were investigated. The phase composition and morphology of the product were further analyzed by XRD and SEM, respectively. The result shows that the main products are WB and WB2 when the B/W ratio is controlled to be 2; however, when the ratio is increased to 2.5 above 1400 oC WB2 of high purity can be obtained. With the B/W ratio more than 4 the main products are mixed by both WB2 and WB4. The relative content of WB4 is increased with prolonging the annealing time. The model of WB4 formation process has been discussed.