Effects of nano-Al2O3 addition on microstructure, mechanical properties, and wear resistance of Ti(C, N)-based cermets

Abstract

To enhance high-temperature wear resistance and cutting performances of cermet tools, nano-Al2O3 particles were added into four kinds of Ti(C,N)-based cermets. The microstructure, mechanical properties, wear resistance, and cutting performances were studied. The nano-Al2O3 was supposed to distribute in the binder phase, leading to the change of lattice constants and dispersion strengthening. Due to the distribution of nanoparticles at the grain boundaries, the movement of the grain boundaries was hindered, and the mean grain size decreased from 1.03 μm to 0.89 μm. The hardness and fracture toughness showed the change tendency of rising the peak and then falling with nano-Al2O3 addition. The cermet with 2 wt% nano-Al2O3 displayed the topmost hardness of 1654.4 HV30 and fracture toughness of 9.1 MPa·m1/2, due to the dispersion strengthening and pinning effect of nano particles. During the sliding wear tests at 700 °C, the wear rates of cermet containing 2 wt% nano-Al2O3 decreased by 63% compared to cermet without nano-Al2O3. The superior high-temperature wear resistance was ascribed to the thermal softening resistance of nano-Al2O3, the strengthening and toughening effect of nano-Al2O3 on matrix and the dense tribo-chemical layers. The abrasive wear of cermet with no nano-Al2O3 addition was more significant, while the wear behavior changed to the removal of tribo-chemical layers when nano-Al2O3 was 2 wt%. The tool life of cermet with 2 wt% nano-Al2O3 was increased by 50% in comparison with cermet without nano-Al2O3 during machining 45 steel.