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

Abstract

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 9wt% WC and a 6wt% TaC, which is sintered at 1400°C with 30min at 30MPa, exhibits the best mechanical properties. This cermet material was then manufactured into cutting tools which maintained good wear resistance after 85min of high-speed cutting stainless steel.