Sintering, thermal stability and mechanical properties of ZrO₂-WC composites obtained by pulsed electric current sintering

Abstract

ZrO₂-WC composites exhibit comparable mechanical properties as traditional WC-Co materials, which provides an opportunity to partially replace WC-Co for some applications. In this study, 2 mol.% Y₂O₃ stabilized ZrO₂ composites with 40 vol.% WC were consolidated in the 1150°C–1850°C range under a pressure of 60 MPa by pulsed electric current sintering (PECS). The densification behavior, microstructure and phase constitution of the composites were investigated to clarify the role of the sintering temperature on the grain growth, mechanical properties and thermal stability of ZrO₂ and WC components. Analysis results indicated that the composites sintered at 1350°C and 1450°C exhibited the highest tetragonal ZrO₂ phase transformability, maximum toughness, and hardness and an optimal flexural strength. Chemical reaction of ZrO₂ and C, originating from the graphite die, was detected in the composite PECS for 20 min at 1850°C in vacuum.

Keywords

ceramic composite / pulsed electric current sintering (PECS) / grain size / mechanical property