Spark plasma sintering and mechanical properties of tungsten carbide in presence of Ni and Al2O3 binders

Abstract

The current study was conducted to investigate the effect of nickel (Ni) and alumina (Al2O3) binders on the sintering behavior, microstructure, and final mechanical properties of WC-based cermets consolidated by the spark plasma sintering (SPS) method. To examine this, batches were mixed according to WC86-(Al2O3)14-x Nix where X= 0, 3, 6 wt % and WC94-(Al2O3)6-x Nix with X= 0, 3; applying high-energy ball milling. Sintering was carried out at temperatures of 1350 °C and 1500 °C. The results revealed that without Ni, in WC-6wt% Al2O3 and WC-14 wt% Al2O3 samples, the relative density and the fracture toughness were less than 94% and 7 MPa m 1/2, respectively. However, with Ni addition and its partial replacement in the microstructure, not only sintering temperature decreased to 1350 °C, but also the obtained relative density was increased to higher than 98% and in the case of WC-3wt%Ni-3wt% Al2O3 cermet, almost full density samples have been achieved. Accordingly, due to better consolidation, this sample exhibited the combination of high strength (1127±53 MPa), high hardness (16.5±0.5 GPa), and proper fracture toughness (15.33 MPa m 1/2).