Plasma synthesis of tungsten carbide and cobalt nanocomposite powder

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 CH4, H-2, and Ar. The reduction and carburization of vaporized precursors produced nanosized tungsten carbide (WC1-x)-cobalt composite powder, which contained small amounts of W2C 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 WC1-x, W2C, 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. (C) 2009 Elsevier B.V. All rights reserved.