Sliding wear behavior of SPS processed TaC-containing Ti(CN)-WC-Ni/Co cermets against Silicon Carbide

Dense (>98.5%) TiCN-WC-Ni/Co cermets with or without TaC are prepared by spark plasma sintering technique at 1400 °C and 70 MPa pressure for 3 min and their friction and wear properties are investigated against commercially available hard counterbody silicon carbide ball at 5, 10 or 20 N load. Core-rim morphology is observed in SEM images of sintered samples which results due to dissolution and reprecipitation process. Vickers Hardness and fracture toughness varied from 15-17 GPa and 8.79 to 9.51 MPa m1/2. Nano hardness of core-rim-binder phases of cermets lie between 11.14-26.01 GPa. Maximum hardness and fracture toughness were obtained for Ti(CN)-5WC-10Ni-10Co-5TaC (in wt%) cermet. With change in the cermet composition and sliding load, coefficient of friction varied from 0.3 to 1.1. Wear rate of cermets varied from 4.7×10−7 mm3/Nm to 2.2×10−6 mm3/Nm and of worn SiC ball from 4.4×10−7 mm3/Nm to 1.5×10−6 mm3/Nm. Hard debris oxides are responsible for higher COF at low load of 5 N and their compaction leads to the formation of tribolayer at high load of 20 N. The worn surfaces of cermets are characterized by microcracking, tribolayer formation and spalling. The addition of TaC in TiCN-WC-Ni/Co cermets led to the refined carbide size having lowest contiguity of ceramic phase and attributed to reduced wear. Present research contributes in context of dry machining conditions and is conducted to explore the potential of new cermet material in severe wear conditions against hard material.