Preparation of WC cemented carbide without metallic binder toughened by MgO-B2O3 via spark plasma sintering at 1400℃

In order to reduce the sintering temperature and obtain higher fracture toughness of WC cemented carbides without metallic binder, WC cemented carbide was toughened by MgO and B2O3. Dense WC-MgO-B2O3 bulk materials were prepared at the relative low temperature of 1400℃ via spark plasma sintering(SPS), and the effects of MgO-B2O3 addition on sintering mechanism, microstructure evolution and mechanical properties of WC cemented carbides without metallic binder were studied. The results show that the addition of MgO-B2O3 promotes the sintering densification of WC, and reduces the sintering temperature of WC cemented carbides without metallic binder. With the increase of MgO-B2O3 contents, the morphology of some second phases in the microstructure is gradually transformed from short rod-shaped to long rod-shaped, and then to aggregated block. When MgO-B2O3 content reaches 8% (mass fraction), the bulk material has better fracture toughness of (9.45±0.37) MPa·m1/2, and its hardness is (18.16±0.17) GPa.