Preparation of tungsten borides by combustion synthesis involving borothermic reduction of WO3

Synthesis, consolidation and characterization of monolithic and SiC whiskers reinforced HfB2 ceramics

“…This feature, quite often encountered during hightemperature synthesis of metal-boride compounds from elemental boron, 22 is generally ascribed to the presence of adsorbed oxygen/moisture in the original powders. Correspondingly, volatile B 2 O 3 is first formed and then expulsed during reaction occurrence, thus producing B deficiency in the reaction environment.…”

Nanoscaled Metal Borides and Phosphides: Recent Developments and Perspectives

“…The latter acts as both reductant and boron source and must be used in excess stoichiometry (eq ) because boron oxide evolves as a side-product. In certain cases, the composition within binary compounds is controlled by adjusting the initial reactant ratio, for instance in the NbB-Nb 3 B 4 –NbB 2 , WB-W 2 B 5 and Cr 5 B 3 –CrB-CrB 2 systems. , 3 Nb 2 normalO 5 ( s ) + 22 B ( s ) → 6 NbB 2 ( s ) + 5 normalB 2 normalO 3 Reactions of boron with metal(0) or metal oxide are usually highly exothermic. As a result, after an initiating step typically above 200 °C, , temperature self-sustains, if not increases.…”

“…In certain cases, the composition within binary compounds is controlled by adjusting the initial reactant ratio, for instance in the NbB-Nb 3 B 4 –NbB 2 , WB-W 2 B 5 and Cr 5 B 3 –CrB-CrB 2 systems. , 3 Nb 2 normalO 5 ( s ) + 22 B ( s ) → 6 NbB 2 ( s ) + 5 normalB 2 normalO 3 Reactions of boron with metal(0) or metal oxide are usually highly exothermic. As a result, after an initiating step typically above 200 °C, , temperature self-sustains, if not increases. These so-called self-propagating high temperature syntheses (SHS) have the advantage of low energy consumption, but they must be carefully controlled for safety concerns.…”

Effects of process parameters on tungsten boride production from WO3 by self propagating high temperature synthesis

“…and W 2 B 5 have been produced by borothermic synthesis method [19]. As initial mixture, they used WO 3 and rather expensive powders which are elemental W and amorphous boron (92 wt.%).…”