Study of graded cemented carbide prepared by stack moulding and spark plasma sintering (SPS)

The dense graded cemented carbide of YG10/YG20 was prepared by using stack moulding and spark plasma sintering (SPS). In order to make the sintering temperature of YG10 and YG20 approached, the different grain size of WC is selected and microelement such as boron is added in the mixed powder YG10. The effect of sintering temperature on density, microstructure, microhardness and fracture toughness property were studied. The component variation near the gradient interface and the variation of microhardness along the cross-section of YG10/YG20 graded cemented carbide were analyzed. The results show that the mixed powder of YG10+0.05% with initial I mu m WC and the mixed powder of YG20 with initial 9 mu m WC can be compacted at a temperature range between 1100 degrees C to 1160 degrees C. The relative density is higher than 99% and the grain size is homogeneous. There has a well combine between the YG10/YG20 graded interfaces. The hardness in layer of YG10 is 15 500 MPa similar to 16 000 MPa and in layer of YG20 is 11 100 MPa; the toughness in YG10 is 12.62 MPa(.)m(1/2) but there has no crack around the indentation in YG20 under the load of 30 kg, the graded cemented carbide has high hardness in one layer and has high toughness in the other layer.