Microstructure and properties of WC-17Co cermets prepared using different processing routes

Abstract

WC-17Co cermets were prepared using three different processing routes. An as-ball milled powder mixture (BMPM) and pre-solid solution treatment powder (PSTP) were used as feedstock. Sinter-hot isostatic pressing (SHIP) and high-velocity oxy-fuel (HVOF) thermal spraying were used as consolidation methods. The microstructure and properties of the WC-17Co cermets prepared using the BMPM-SHIP, PSTP-SHIP, and PSTP-HVOF routes were characterized and systematically compared. Solid-solution strengthening of the Co binder phase accounted for the higher hardness and lower fracture toughness (KIC) of the cermets produced using the PSTP-SHIP and PSTP-HVOF routes compared with those of the BMPM-SHIP-produced cermet. Moreover, the SHIP method yielded WC grains featuring an equilibrium truncated triangular prism morphology, which were faceted compared to the round-edged WC grains prepared using HVOF. Owing to the formation of a dense protective tribofilm on its surface, the cermet prepared using the BMPM-SHIP route exhibited the lowest wear rate of 0.13 × 10−7 mm3/(Nm), while the wear rates of the cermets prepared using PSTP-SHIP and PSPT-HVOF were 0.24 × 10−7 and 0.96 × 10−7 mm3/(Nm), respectively.