CHEMICAL-PROCESSING OF NANOPHASE WC-CO COMPOSITE POWDERS

The future development of advanced engineered materials for structural electrical, magnetic, catalytic, and other applications will depend to an increasing extent on improved control of the size, distribution, and morphology of the constituent phases of the materials. In advanced materials systems, this development is in the direction of diminishing scale and increasing uniformity of the structure, extending into the nanoscale regime. The capabilities for synthesising novel nanophase structures are now becoming available in the laboratory and efforts are being made to scale up these processes to produce the quantities required for prototype development, field testing, and commercial applications. This paper addresses the scientific and technical issues relating to the chemical processing of nanophase WC-Co composite powders and the integration of the various processing steps into a new spray conversion processing technology. The new technology involves three coordinated steps: preparation and mixing of starting solutions; spray drying to form chemically homogeneous precursor powders; and fluid bed thermochemical conversion of the precursor powders to nanophase WC-Co powders. Both spray drying and fluid bed conversion are proven scalable technologies and offer the potential for producing bulk quantities of cemented carbide powders at lower manufacturing cost.