HIGH TEMPERATURE EROSION WEAR OF TiCN-BASED CERMETS

Abstract

In order to improve wear resistance of cermets for the use in cutting tool applications, development of new compositions is necessary. The purpose of the preset work is to prepare dense TiCN-10 wt% Mo2C-10 wt%WC-10 wt%Ni-10 wt% Co cermets with restricted coarsening by ball milling and spark plasma sintering and estimate the potential of the sintered cermets in erosion wear conditions. The reduction of commercially available TiCN and Mo2C powders by milling and further mixing with other constituents for 8 to 72 h resulted in oxidation products. Spark plasma sintering at 1200- 1300oC and 40-50 MPa resulted in 97-98% dense cermets. The microstructure of the developed cermets reveals black core of TiCN, white cores and grey rim of (Ti, W, Mo)CN. Typical hardness of 10.48 GPa and fracture toughness 9.44 MPam1/2 are obtained for cermets sintered using 72 h mixed powders. Erosion by SiC particles of at normal incidence reveals removal of binder phase and pull-out or fracture of ceramic grains. At elevated temperature of 400oC, easy removal of binder phase resulted in increased fracture of ceramic grains, leading to 1.5 to 2 times erosion compared to erosion at room temperature.