Enhanced thermal stability and wear resistance of TiCN-SiC-TiN-Cr3C2-Co cermet modified by B4C for cutting tool application

In this work, a suitable cermet compositions based on TiCN-SiC-TiN-Cr₃C₂-Co-B₄C is identified for cutting tool purpose. The cermets were sintered using spark plasma sintering with the addition of different weight percentages of B₄C (5%, 10%, 15%) in TiCN - SiC - TiN - Cr₃C₂ - Co cermets. The cermets were subjected to the annealing process at three different temperatures of 600 °C, 800 °C, and 1000 °C for a constant soaking time of 4 h to study their thermal stability. All the cermets' compositions showed good thermal stability up to 800 °C and 55% TiCN – 15% SiC – 5% TiN – 5% Cr₃C₂–10% Co – 10% B₄C cermets showed better thermal stability up to 1000 °C. There was a change in microstructure and formation of the oxide phases in the cermets during the high temperature (1000 °C) annealing process and overall lead to a decrease in hardness. The sintered cermets were also subjected to sliding wear in the pin on disk apparatus. EN31 steel disk was used as a counter disk. The wear testing was done at different loads (20 N, 25 N, 30 N, 35 N) and at different sliding velocity (0.55 m/s, 1 m/s, 1.5 m/s, 2 m/s) with a constant track distance of 1000 m. Wear rate was at its highest value of 9.74 × 10^?7 mm³/Nm for the cermet 65% TiCN - 15% SiC - 5% TiN - 5% Cr₃C_2?10% Co and the lowest wear rate noted was 1.18 × 10^?7 mm³/Nm for cermet 55% TiCN - 15% SiC - 5% TiN - 5% Cr₃C_2?10% Co – 10% B₄C and the B₄C addition has improved the wear resistance of the cermets.