Cutting properties of the Al₂O₃ + SiC_(w) based tool ceramic reinforced with the PVD and CVD wear resistant coatings

The paper presents investigation results of tribological properties of the coatings deposited with the PVD and CVD techniques on cutting inserts made from the Al₂O₃ + SiC_(w) oxide tool ceramic. Tests were carried out on the multipoint inserts made from the Al₂O ₃ + SiC_(w) oxide ceramics, uncoated and coated with gradient, mono-, multilayer and multicomponent hard wear resistant coatings composed of TiN, TiCN, TiAlN, TiAlSiN and Al₂O₃ layers with PVD and CVD processes. Substrate hardness tests and microhardness tests of the deposited coatings were made on the ultra-micro-hardness tester. It was demonstrated, basing on the technological cutting tests of spheroidal cast iron, that putting down onto the tool ceramics the thin anti-wear coatings in the PVD and CVD processes increases their abrasion wear resistance, which has a direct effect on extending the tool edge life. Basing on the roughness parameter R _a of the machined cast iron surface after the cutting tests, improvement was revealed of the machined material properties, cut with coated oxide ceramics compared to material machined with the uncoated tools.