Si3N4 ceramic cutting tool sintered with CeO2 and Al2O3 additives with AlCrN coating

Ceramic cutting tools are good candidates for cast iron and nickel superalloy machining. The development of Si3N4-based ceramic cutting inserts, characterisation of their physical and mechanical properties, and subsequent coating with AlCrN using PVD were studied. The coating was characterised using optical profilometry, XRD, AFM and microhardness testing. The tool had a fracture toughness of 6.43 MPa.m1/2 and hardness of 16 GPa. The hardness reached 31 GPa after coating. The machining tests showed a decrease on workpiece roughness when machining with the coated insert, compared with the uncoated cutting tool. This is probably related to the hardness, roughness and topography of AlCrN.