Development of TiCN-Co-Cr3C2-Si3N4-based cermets with improved hardness and toughness for cutting tool applications

Abstract

ABSTRACT A TiCN-Co-Cr3C2-based cermet, with the addition of 5wt. % and 10wt. %Si3N4 and a reference sample without Si3N4 addition were prepared by the spark plasma sintering technique. The average hardness and fracture toughness of the 90TiCN-5Co-5Cr3C2(SN00) cermet-sintered specimens were e14.85±3.11 GPa and 6.78±0.61 MPaÖm, respectively. The cermet composition 85TiCN-5Co-5Cr3C2-5 wt. % Si3N4(SN05) enhanced the hardness and fracture toughness to 20.90±0.825 GPa and 7.23±0.45 MPaÖm, respectively. Further addition of 10 wt%Si3N4 with 80TiCN-5Co-5Cr3C2(SN10) decreased the hardness value to 16.18±0.279 GPa due to a decrease in the density of defects. However, the fracture toughness steadily increased to 9.34±3.10 MPaÖm. The cermet composition 85TiCN-5Co-5Cr3C2-5Si3N4 (SN05) showed an appreciable improvement in hardness and toughness values due to the formation of a core-rim structure, with the core consisting of TiCN and the rim with TiN, TiO2, TiSi, Co2C, CrN and Cr2Si.