Preparation and sintering of WC–Co composite powders for coarse grained WC–8Co hardmetals

Abstract

Due to high chemical and geometrical irregularities of WC grain and high uncertainty of WC grain growth, it is hard to prepare coarse grained WC–Co hardmetals with high performance through sintering of WC–Co ball milling powder. A new method for preparing of WC–8Co composite powder is put forward, which merges the preparation of Co powder with the mixing of WC–Co. The compositions, phases, and shapes of WC–8Co composite powder were investigated by chemical element analysis, X-ray diffractometry (XRD), and scanning electron microscopy (SEM), respectively. The phase and shape of raw WC powder do not change during the preparation of WC–8Co composite powder. Microstructures and mechanical properties of WC–8Co hardmetals prepared by sintering of the composite powders were compared with those of WC–8Co hardmetals prepared by sintering of the ball milling powders. The results show that the new coarse grained WC–8Co hardmetals have a better performance than conventional WC–8Co hardmetals for their better uniformity of WC grains. The comparison of microstructures and mechanic properties of sintered alloys also confirms that VC further inhibits the growth of WC grain and improves the performance of WC–8Co hardmetals.