The impact of recycling process for tungsten cemented carbide products by using powder metallurgy technique

Abstract

Recycling of cemented carbides or hard metals is attracting considerable interest worldwide because of their superior mechanical and physical properties. This work 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 is used for preparing cutting tools. Various compaction pressures from 250 to 730 MPa and sintering temperatures from 1350 to 1450 ̊C were used in the study. The density, hardness and fracture toughness weremeasured for all sintered samples. The highest relative density and hardness values are 98% and 1710 HV30, respectively for the sample compacted at730 MPa and sintered at 1450 ◦C, while the highest value of fracture toughness is 11.657 MPa.m1/2 for the sample compacted at 460 MPa and sintered at 1350 ◦C. Statisticalanalysis showedthat the most suitablecompaction pressureand sintering temperature are460 MPa and1400 ̊C,respectively. The prepared samples are 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 is mixedwith the fresh one by 10, 20, 30...and 100 wt. %and is used to manufacture new samples. Results have shown that 70wt.% recycled powder is the optimal mixing composition.