Preparation and properties of Ti(C,N)-based cermets with graphene nanosheet addition by spark plasma sintering

Abstract

The application of Ti(C,N)-based cermets remains limited due to their low toughness. The fracture toughness of cermets can be significantly improved by using advanced sintering methods and appropriate additives. Here, cermets were prepared by spark plasma sintering (SPS) technology with graphene nanosheets (GNSs) and nano-scale tungsten carbide (WC) as additives. The effects of GNSs and sintering conditions on the microstructure, mechanical properties, and magnetic properties of Ti(C,N)-based cermets were studied. The results show that the sample with 0.6 wt% GNSs fabricated at 1450 °C, 8 min, and 35 MPa has a denser microstructure and better mechanical properties. The cermet has a Vickers hardness of HV 2415.40 and fracture toughness of 10.6 MPa·m1/2. Compared with the specimen without GNSs, the hardness and fracture toughness are significantly improved by 44.58% and 92.73%, respectively. A certain amount of GNSs can increase the movement of hard phases in the liquid phase, inhibiting their solubility and grain growth, and greatly improving the fracture toughness of cermets. The addition of nano-WC is conducive to promoting the formation of a (Ti,W) (C,N) rim phase and improving properties of cermets. SPS can activate particle surfaces and promote the densification of cermets.