Mechanical properties and erosion resistance of ceria nano-particle-doped ultrafine WC-12Co composite prepared by spark plasma sintering

Ultra-fine grained WC-Co composites possess higher hardness or strength and wear resistance, compared to their coarse counterparts. However, abnormal grain growth of ultra-fine WC particles often occurs during the traditional pressureless liquid sintering, which substantially impairs the mechanical properties and erosion resistance of the material. Thus, controlling the abnormal grain growth becomes one of the key issues in fabricating ultra-fine grained cemented carbides. In this study, ultra-fine grained WC-Co composites containing different amounts of ceria nano-particles were prepared by spark plasma sintering and effects of the nano-ceria on mechanical properties and erosion behavior of the WC-Co composites were studied. The results demonstrated that trace nano-ceria addition effectively suppressed the abnormal grain growth of WC, leading to uniform and fine microstructures. Such ultra-fine grained WC-Co composites have both improved hardness and fracture toughness, resulting in enhanced resistance to high-speed solid-particle erosion. However, when the added nano-ceria was more than 0.1 wt%, Co pools started to form, which lowered the material density, hardness and toughness and consequently the erosion resistance.