Effects of sintering processes on mechanical properties and microstructure of Ti(C,N)-TiB_2-Ni composite ceramic cutting tool material

摘要

Ti(C,N)-34.2 wt% TiB_2-5 wt% Ni composite ceramic cutting tool material was fabricated by vacuum hot pressing sintering method in six processes with different holding stages, holding time and heating rates. The influences of sintering processes on the mechanical properties and microstructure were studied. The polished surface and fracture surface of Ti(C,N)-TiB_2-Ni ceramics were observed by scanning electron microscope, energy-dispersive spectrometry and X-ray diffraction, and the relationships between mechanical properties and microstructure were investigated. The mechanical properties and microstructure depended primarily on the different holding stages, holding time and heating rates. The results showed that the Ti(C,N)-TiB_2-Ni composite ceramic cutting tool material sintered by SP3 process (three holding stages, holding time of 30 min and the heating rate of 50 °C/min) exhibited the optimum mechanical properties because of its finer microstructure, and the corresponding values were as follows: flexural strength of 967.7 ± 90 MPa, fracture toughness of 7.07 ± 0.8 MPa/m~(1/2) and Vickers hardness of 20.22 ± 2.1 GPa respectively.