Effects of oxide addition on structure and properties of WC-10Co cemented carbide obtained by in situ synthesized powder

Combining spray drying and in situ synthesized technology, WC-10Co cemented carbide with uniform composition was prepared by vacuum sintering. The effects of Al2O3 and additions of different rare-earth oxides (La2O3, Y2O3 and CeO2) on the microstructure and mechanical properties of WC-10Co were investigated. As the Al2O3 content increased from .5 to 2 wt%, the hardness of the sintered sample increased, whereas the relative density and fracture toughness decreased. Compared with the addition of .5 wt% Al2O3, the WC-10Co alloy with .5 wt% rare-earth oxides had higher hardness. In addition, compared with the alloy without an inhibitor (.80 mu m), after adding .5 wt% Al2O3, La2O3, Y2O3 and CeO2, the WC grain sizes were reduced to .73, .65, .71 and .62 mu m, respectively, which indicated that the addition of Al2O3 and rare-earth oxides could refine WC grain during sintering. Among these additives, CeO2 had the best effect. With the addition of .5 wt% CeO2, the hardness and the fracture toughness increased from 1299 to 1710 HV30 and from 16.18 to 18.90 MPa m(1/2), respectively.