Characterization of metal powder suspension to improve the functionality of cemented carbides

Cemented carbide is produced by sintering a mixture of metal carbides and binder. Both materials are formed into granulated powders via suspension with the object of a uniform product and an easy handling. And the granule was sintered to produce final products. In addition to excellent toughness and wear, accurate and minute figuration is required for commercial products. The method to produce the granulated powders significantly affects those properties rather than latter processes, because the interaction between materials plays a notable role for the particle agglomeration in a suspension. Because of sedimentation of materials, however, the agglomeration in a suspension had ever been difficult to evaluate, and those operating conditions were decided semi-empirically. In this study, the extent of particle agglomeration was evaluated by the measurement of viscosity; further the relationship between the particle interaction and the properties of granules was investigated. As a result, suspensions with a small addition of surfactant showed almost constant particle and provided similar granules. However, much more addition than critical resulted in the decrease of the particle interaction and strength of granulated powder.