Effect of the Conditions of Formation of W–C Nanopowders in a Plasma Jet on the Synthesis of Hexagonal Tungsten Carbide

Resumo

The effects of the conditions of a raw material introduction as well as mixing of it with a high-temperature gas flow under the plasma chemical synthesis of superdispersed powder of W–C have been studied. In the case of incomplete raw material evaporation and its fast quenching, preferred cubic tungsten carbide β-WC formation is found to occur, as well as nano- and microparticles with a complicated phase composition. In the case of complete raw material evaporation, the products of reducing synthesis are nanopowder of tungsten or semicarbide W₂C depending on the amount of hydrocarbon introduced. There is a second stage of the process of low-temperature synthesis which leads to a single-phase of tungsten carbide α-WC formation. Complete evaporation of raw material must be ensured in the plasma chemical process for obtaining of α-WC powder with a maximum specific surface area.