Wear and high-temperature stability of TiCN-WC-Co-Cr3C2-HfC-Si3N4 cermets

This work reports the wear and high-temperature stability of TiCN-WC-Co-Cr3C2-HfC-Si3N4 cermets developed by spark plasma sintering (SPS). The addition of Si3N4 in the range of 5 wt. % to 15 wt. % in TiCN-WC-Co-Cr3C2-HfC cermet composition showed hardness of the cermets in the range of 10.2 +/- 0.05 to 11.7 +/- 0.05 GPa. Among the three cermets developed, 60TiCN-15WC-10Co-5Cr(3)C(2)-5HfC-5Si(3)N(4) possessed a hardness value of 11.7 +/- 0.05 GPa and fracture toughness value of 15.1 +/- 3.5 MPa root m. The wear behaviour of the cermets was studied using a pin-on-disc machine with cermets as a pin on EN 31 steel counter disc material with three different sliding velocities in the range of 0.23-0.35 m/s, at a constant normal load of 20 N for a duration of 5 min. 60TiCN-15WC-10Co-5Cr(3)C(2)-5HfC-5Si(3)N(4) cermet showed a high wear resistance at all the three sliding velocities compared to the other cermet composition. High-temperature stability of the cermets was assessed by heating the cermet samples to 600 degrees C, 800 degrees C and 1000 degrees C and holding them for about 4 h followed by cooling within the furnace itself. All the three cermets were stable up to 800 degrees C. Cermet 60TiCN-15WC-10Co-5Cr(3)C(2)-5HfC-5Si(3)N(4) showed less affinity for oxidation after heating, and hence, it has good thermal stability than other cermet compositions.