Using the oxygen containing particles for in-situ formation of tungsten nano-particles by oxidation-reduction mechanism

Abstract In this paper, two fold effect of addition of submicron particles on the solid state sintering of tungsten compact was investigated. Firstly, addition of submicron particles can reduce overall particle size of compact and then, activate the sintering of tungsten by increasing the driving force related to total surface energy of the system. On the other hand, an interesting phenomenon during the solid-state sintering of tungsten skeleton was reported. In this phenomenon, WO3 nanowires were formed on tungsten particles by Vapor-Solid (VS) mechanism due to the high oxygen content of sub-micron particles as a required oxygen source. In addition, hydrogen reduction of WO3 nanowires in hydrogen atmosphere led to the formation of tungsten nanoparticles. The results of this study can provide a new insight related to solid state activated sintering of refractory metals. The obtained results showed that, addition of 20wt.% sub-micron particles to micro powders can enhance densification of tungsten compact from 67% to 77% at temperature as low as 1650°C.