The Study About Manufacture Technics Of CX1 Ultrafine WC-TiC-TaC-Co Cemented Carbides

The ultrafine CXI WC-TiC-TaC-Co composite powder with an average particle size of 0.25 μm was made of micro-size WC, WC-TiC-TaC, TaC and Co powers which had been milled 60 hours with high-energy ball milling. The powers were pressed by compression molding at 200Mpa, the pressure keep 2mins the density of pressed shape was 6.82 ·cm-3. The samples were sintered by vacuum sintering technique at 1360℃,1380℃,1390℃ andl400℃. The density, hardness, transverse rupture strength, coercitive force and relative saturation magnetization of CXI samples were detected. The morphology, metallic phase and SEM micrograph of alloy’s section were analyzed. the results of research as follows:The optimum sintering temperature for CXI samples was 1380℃, under this condition, the relatively density, transverse rupture strength, hardness, coercitive force and relative saturation magnetization of CXI samples were 98.8%,1700MPa,92.0HRA,17.53 KA·m-1 and 69.63% respectively. The grain size of CXI samples were range from 0.3μm to 1.Cμm,average grain size was 0.7μm. Metallography analyzing showed that there were five metallurgical structure,they were WC, (Ta、W)C, (Ti、Ta、W)C, Co3W3C and Co.When the CXI sample was doped 0.5wt%VC and 0.5wt%Cr3C2 inhibitors, the samples were prepared by 60 hours milling,200MPa molding and 1380℃ sintering. The relatively density, transverse rupture strength, hardness, coercitive force and relative saturation magnetization of CXI s-amples were 98.4%,1770MPa,93.2HRA,36.13 KA·m-1 and 69.13% respectively. The inhibitors had very significant inhibitive effects on WC’s grain size, WC’s grain size was ultrafine that ranged from 0.2μm to 0.5μm, grain size of few WC and (Ti、 Ta、W)C reached 1μm,average grain size was 0.4μm, the result showed the inhibitors were not evenly distributed that made grain size of a few WC became extremely large. The inhibitors had no effect on the grain size of (Ti、Ta、W)C.