A new type of high flexural strength micro-nano-composite ceramic tool material Ti(C,N)/WC/ZrO2 for integrated micro milling cutter

Abstract

Ti(C,N) composites are widely applied in various advanced manufacturing industries. However, the intrinsic brittleness and relatively high metal content for Ti(C,N) composites significantly limit their further applications, especially in high-temperature and high-speed machining conditions. Herein, a new type of high flexural strength micro-nano-composite ceramic tool material Ti(C,N)/WC/ZrO2 for integrated micro milling cutter which will be used to mill difficult-to-machine material such as titanium alloy was proposed and developed successfully by hot press sintering technique under vacuum. The Ti(C,N) composites with low metal phase strengthened by nano-3Y-ZrO2 and micro-WC particles, the effect of compositions and sintering parameters on the mechanical properties and microstructure of the composite ceramic materials were systematically investigated. The results demonstrated that the Ti(C,N) composites with low metal phase containing 15 wt% nano-3Y-ZrO2 and 15 wt% micro-WC, sintered at 32 MPa and 1500 °C for 45 min had the optimal mechanical properties under vacuum and the flexural strength, Vicker's hardness, fracture toughness and relative density were 1501 ± 86 MPa, 19.97 ± 0.43GPa, 7.25 ± 0.76 MPa.m1/2 and 99.55%, respectively. Meanwhile, the superior mechanical properties of the Ti(C,N) composites with low metal binder phase could be achieved when sintered at higher temperatures and longer holding times compared to conventional cerments. Moreover, the toughening and strengthening mechanisms for Ti(C,N) composites with low metal phase are the synergistic effects of crack bridging, crack branching, crack deflection, pinning effect, particle pull-out, intragranular microstructure, transgranular and intergranular fracture. These toughening and strengthening mechanisms and the solid solution effects generated by the joint action of oxides and carbides could remarkably improve the properties for the Ti(C,N) composites. In this study, a novel insight on developing high-property Ti(C,N) composites was proposed, and it will make a significant contribution to material synthesis and design, application for cutting tools and composite ceramics investigations.