Wear and thermal stability of nano-TiB₂ modified TiCN-WC-Co-Cr₃C₂ cermet

This work discusses the friction, wear and thermal response of TiCN-WC-Co-Cr3C2 cermet modified by the addition of Ti(B)2 nanoparticles. The specimens were prepared by spark plasma sintering by adding different weight percentages (5, 10 and 15) of TiB2 nanoparticles in TiCN-WC-Co-Cr3C2 cermets. The sintered pieces were subjected to sliding wear under an unlubricated condition and a constant load of 20 N at sliding velocities of 0.23 m/s, 0.35 m/s and 0.47 m/s against a steel disc of 48 mm diameter. Friction was the maximum at a sliding velocity of 0.23 m/s. The wear loss decreased with increasing speed of sliding and was between 10(-5) to 10(-6) mm(3). The wear rates and coefficient of friction were highly dependent on microstructure and mechanical properties of the cermets. Abrasion and adhesion were the active modes of wear. Heating of the samples was carried out at 600 degrees C, 800 degrees C and 1000 degrees C for 4 h. A substantial mass gain and decrease in hardness were observed in the specimen annealed at 1000 degrees C, for which Scanning Electron Microscopy revealed considerable grain growth and XRD showed oxide phases. A cermet containing 15% TiB2 nanoparticles displayed the lowest volumetric wear at room temperature, but had rather low thermal stability. Response surface methodology was used to develop models and regression equations for wear and thermal stability.