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 microstructure when compared with conventionally sintered samples. Microstructural 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.