Properties of Ti(C,N)-based cermets reinforced with ZrO2 whiskers deposited via sulfate flux at high temperatures

Abstract

Ti(C,N)-based cermets were prepared by vacuum hot-pressing sintering enhanced by the second phase of ZrO2 whiskers via sulfate flux. The effects of ZrO2 whiskers on the material properties of Ti(C,N)-based cermets at high temperature are discussed, including the room temperature microstructure, high-temperature oxidation resistance, and microstructure and mechanical properties at high temperature. The experimental result indicated that the addition of ZrO2 whiskers improves the bending strength, fracture toughness, and oxidation resistance of Ti(C,N)-based cermets at high temperature. At a temperature of 1000 °C, the hardness, flexural strength, fracture toughness and elasticity modulus of the cermets with 7.5 wt% ZrO2 whiskers were 9.32 GPa, 1032 MPa, 6.71 MPa m1/2 and 193.5 GPa, respectively. The high-temperature strength and toughness of Ti(C,N)-based cermets with ZrO2 whiskers were weakened by the softening of grain boundaries, the decrease in elastic modulus, and oxidation. Conversely, the high-temperature strength and toughness of Ti(C,N)-based cermets were increased by maintaining the rod crystal shape of ZrO2 whiskers at a high temperature, enhanced the elastic modulus of cermets through the whiskers, and improved oxidation resistance.