Effect of WC particle size on Co distribution in liquid-phase-sintered functionally graded WC-Co composite

摘要

Functionally graded WC-Co materials can be manufactured by controlling liquid phase migration or liquid redistribution during liquid phase sintering. The driving force of liquid phase migration is liquid migration pressure P_m which depends on the solid particle size d and the liquid phase volume fraction u. In this study, the effect of d on P_m has been studied experimentally for WC-Co system. The results show that P_m is proportional to l/d~(0.4) which is different from previous postulation that P_m is proportional to l/d. The reason for this difference is that the previous postulation was based on the assumption that all the solid particles in a composite are mono-sized and isometric-shaped, while in real WC-Co composites WC particles usually have non-isometric shape and there is a wide particle size distribution. The dependence of P_m on both d and u has been quantitatively established, enabling the prediction of final Co composition gradient in liquid-phase-sintered WC-Co composites.