Structure and properties of PVD and CVD coated Al2O3 + TiC mixed oxide tool ceramics for dry on high speed cutting processes

The paper presents investigation results of structure and properties of the coatings deposited with the PVD and CVD techniques on cutting inserts made from the Al2O3 + TiC oxide tool ceramic. The investigation includes the metallographic analysis on the transmission and scanning electron microscope, chemical composition analysis as well as the analysis of the mechanical and functional properties of the material. Tests were carried out on the multipoint inserts made from the Al2O3 + TiC oxide ceramics, uncoated and coated with multi-layer hard wear resistant coatings composed of TiN, TiCN, TiAlN, TiAlSiN and Al2O3 layers with PVD and CVD processes. It was demonstrated that adhered closely to each other were characterized by good adhesion to the substrate. It was demonstrated, basing on the technological cutting tests of grey 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 Ra 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.