Recycling of WC-TiC-TaC-NbC-Co by zinc melt method to manufacture new cutting tools

This paper discusses manufacturing of tungsten carbide cutting materials from both fresh powders and recycled ones. As received powder with nominal chemical composition of WC-9% Co-6% TiC-1% TaC-1%NbC was used for preparing cutting tool. Various compaction pressures from 250 to 730 MPa and sintering temperatures from 1350 to 1450 degrees C were used in the study. The density, hardness and fracture toughness were estimated for all sintered samples. Statistical analysis showed that the most suitable compaction pressure and sintering temperature are 460 MPa and 1400 degrees C, respectively. The highest relative density and hardness values are 98% and 1710 HV30, respectively for the sample compacted at 730 MPa and sintered at 1450 degrees C, while the highest value of fracture toughness is 11.657 MPam(1/2) for the sample compacted at 460 MPa and sintered at 1350 degrees C. The prepared samples were recycled by zinc melt method and the best ratio of zinc to carbide is 1.4: 1, which has the highest efficiency of recycled powders (91.55-97.28%). The recycled WC powder was mixed with the fresh one by 10, 20, 30 ... and 100 wt% and was used to manufacture new samples. Results have shown that 70 wt% recycled powder is the optimal mixing composition.