Effects of the addition of multi-walled carbon nanotubes on the microstructure and properties of Ti(C,N)-based cermets prepared by spark plasma sintering

To improve the toughness of Ti(C,N)-based cermets, multi-walled carbon nanotubes (MWCNTs) and nano-WC were added, and spark plasma sintering (SPS) technology was applied. The effects of the addition of MWCNTs on the phase composition, microstructure, and the comprehensive properties of Ti(C,N)-based cermets were investigated. The results show that the cermet (0.4 wt% MWCNTs) prepared by SPS (1350 °C, 16 min, and 35 MPa) has uniform microstructure and excellent comprehensive properties. The hardness and fracture toughness of this sample reach maximum values of HV 3050.29 and 10.90 MPa·m1/2, respectively. Compared with the sample without MWCNTs, the values are increased by 82.57% and 105.66%, respectively. A small number of carbon atoms from the MWCNTs enter the lattice of Ti (C,N) solid solution, which is conducive to improving the bonding ability and high-temperature wettability between MWCNTs and the matrix, thus enhancing the strength and toughness of the matrix materials. The addition of MWCNTs plays a bridging and toughening role at different interfaces. Moreover, the addition of nano-WC is conducive to the plastic flow and particle rearrangement of hard particles at high temperature.