Study of a hot-pressed sintering preparation of Ti(C7N3)-based composite cermets materials and their performance as cutting tools

• Total addition of 15 wt% WC and TaC caused improvements of mechanical properties.
• Higher temperature depressed mechanical properties due to fast grain growth.
• Sintered Ti(C7N3)-based tools exhibited good performance in high-speed turning.
• Sintered Ti(C7N3) tools are appropriate for machining martensitic stainless steel.

Various ratios of superfine WC and TaC particles were added into Ti(C7N3) matrices, and Ti(C7N3)-based composite cermets tool materials were prepared using a hot-pressed sintering technology by various processes. The effects of the superfine WC and TaC particles and sintering processes on the mechanical properties and microstructure were thoroughly investigated. The addition of superfine WC depressed the mechanical properties, but the addition of superfine WC and TaC together refined the microstructure, which optimised the mechanical properties of materials. Both a longer holding time and a higher sintering temperature facilitated the growth of (Ti,W,Ta,Mo)(C,N) grains that caused a reduction in the flexural strength and fracture toughness. A Ti(C7N3)-based cermets tool material with a 9 wt% WC and a 6 wt% TaC, which is sintered at 1400 °C with 30 min at 30 MPa, exhibits the best mechanical properties. This cermet material was then manufactured into cutting tools which maintained good wear resistance after 85 min of high-speed cutting stainless steel.

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