Microstructural tuning of the core–rim structure and wear resistance of Ti(C,N)-based cermets by Si₃[jls-end-space/]N₄additions

This study investigates the influence of Si₃N₄ additions (0–6 wt%) on the microstructure and tribological performance of Ti(C,N)-based cermets fabricated by powder metallurgy and vacuum sintering. Microstructural characterization using SEM, TEM, EDS, and XRD revealed that 2 wt% Si₃N₄ (SN2 sample) promoted a refined, uniform core–rim structure with smoother elemental transitions and reduced d-spacing. The SN2 sample exhibited optimal fracture toughness (10.82 MPa m^1/2), adequate hardness (1494 kgf/mm²), and high transverse rupture strength (1425 MPa). Ball-on-disk tests using Al₂[jls-end-space/]O₃ counter balls showed the lowest coefficient of friction (0.45) and wear rate (2.3 ×10⁻⁶mm³/(N m)) for SN2 sample, attributed to improved grain boundary integrity and stable tribolayer formation. In contrast, 6 wt% Si₃N₄ led to surface damage and decreased wear resistance. These results emphasize the critical role of additive optimization in enhancing the mechanical and tribological properties of Ti(C,N)-based cermets for advanced cutting tool applications.