Comparison between microwave and conventional sintering of WC/Co composites

WC/Co samples sintered in a microwave field differ radically in terms of phases, chemistry, and micro-structure when compared with conventionally sintered samples. Micro-structural investigations by TEM showed that in microwave sintered material the cobalt phase dissolved nearly no tungsten, whereas in conventionally sintered samples up to 20 wt.% tungsten was dissolved in the cobalt binder phase. Besides, smaller WC grains and finer and more uniform distribution of cobalt binder were observed in microwave sintered samples. This resulted in a harder material, which also exhibited better resistance towards both corrosion and erosion. Microwave sintered samples also have a three-dimensional uniform shrinkage, whereas conventionally sintered samples showed a greater vertical shrinkage. It is possible to microwave sinter WC/Co at lower surface temperature and in much shorter times than normally needed in a conventional furnace to obtain the same degree of densification.

E. Brevala,∗, J.P. Chenga, D.K. Agrawala, P. Gigla, M. Dennisb, R. Roya, A.J. Papworthc