Synthesis, sintering, and mechanical properties of nanocrystalline cemented tungsten carbide - A review

Nanocrystalline WC-Co materials have been the subject of interests and focus of research programs around the world for the past two decades owing to the expectations that the mechanical behavior of the material may improve significantly when grain sizes reduce to nanometer scale. However, although numerous technologies are available for making nanosized tungsten carbide powders, obtaining true nanocrystalline WC-Co (average WC grain size <100 nm) has been a great challenge due to the difficulties of controlling grain growth during sintering. Evaluation of the mechanical properties of nanocrystalline WC-Co materials is also difficult because there is little published data that are based on specimens with truly nanoscale grain sizes. In this review, the challenges and results of sintering nanocrystalline WC-Co powders will be examined as well as the various technologies for producing nanosized tungsten carbide powders. It will be discussed that the key challenge to the production of bulk nanocrystalline cemented tungsten carbide materials is to control the rapid grain growth during the early stage of sintering. The current understanding on the mechanical properties of cemented tungsten carbide made from nanoscaled WC-Co powders will also reviewed. (C) 2008 Elsevier Ltd. All rights reserved.