Effect of plasma sintering process on the mechanical properties of WC/Cr₃C₂/La₂O₃ cutting tool materials

To solve the problem of adhesive phase wear for the traditional cemented carbide tools in the high-speed cutting process, the WC/Cr₃C₂/La₂O₃ tool materials were prepared by spark plasma sintering (SPS). The effects of Cr₃C₂ addition amount (mass fraction, 0%~2.00%) and process parameters (sintering temperature 1500~1700 ℃ and sintering pressure 15~45 MPa) on the microstructure and mechanical properties of the tool materials were studied. The results show that, the optimum Cr₃C₂ content is 0.50%, and the WC/Cr₃C₂/La₂O₃ cemented carbide sintered at 1550 ℃ and 25 MPa has the best comprehensive properties as the relative density, bending strength, and Vickers hardness are 97.5%, 1281.0 MPa, and HV 2124.3, respectively. With the increase of sintering temperature, the relative density increases and the microstructure becomes more even for the WC-based tool materials. However, too high temperature leads to the abnormal growth of grains, the uneven distribution of microstructure, more porosity, and the lower mechanical properties. As the sintering pressure increases, the grain size reduces, the microstructure becomes more even, and the mechanical properties increase. While the sintering pressure is above 25 MPa, the mechanical properties of tool materials decrease.