Plasma synthesis of tungsten carbide and cobalt nanocomposite powder

Abstract

Nanosized tungsten carbide–cobalt composite powder was synthesized by a thermal plasma process, in which ammonium paratungstate (APT) and cobalt oxide were reacted with a gas mixture containing CH 4, H 2, and Ar. The reduction and carburization of vaporized precursors produced nanosized tungsten carbide (WC 1− x )–cobalt composite powder, which contained small amounts of W 2C and/or W phase. The particle size of synthesized tungsten carbide powder was less than 20 nm. The synthesized composite powders were also subjected to a hydrogen heat treatment to fully carburize WC 1− x , W 2C, and W phases to the WC phase as well as to remove excess carbon in the product. Finally nanosized WC–Co composite powder of particle size less than 100 nm was obtained.