Structure and mechanical properties of gradient PVD coatings

The paper presents investigation of the Ti(C, N) and (Ti, Al)N gradient coatings deposited with use of the cathodic arc evaporation CAE-PVD method on sintered tool materials: cemented carbides, cermets and Al2O3 + TiC oxide tool ceramics.The investigation includes the metallographic analysis on the scanning electron microscope (SEM). The X-ray qualitative microanalysis and surface distribution analysis of elements in the investigated materials were made using the EDS X-ray energy dispersive radiation spectrometer. Moreover the investigation includes analysis of the mechanical and functional properties. Tests of the coatings adhesion to the substrate material with use of the scratch test and surface roughness tests were done both before depositing the coatings and after completing the PVD process.It has been showed that investigated materials are characteristic of the dense, compact structure and their fracture surface topography attests to their high brittleness, characteristic especially for the oxide ceramic materials.The results of roughness and microhardness tests confirm the advantages of the multicomponent (Ti, Al)N and gradient Ti(C, N) coatings. As results of the examination of coating microhardness it has been found that multicomponent and gradient coatings on the investigated materials causes the 35–76% increase of microhardness value. Depositing the wear resistant coatings onto the tool cemented carbide, cermet, and oxide tool ceramics results in a significant increase of the surface layer microhardness, contributing most probably in this way in machining to the decrease of the wear intensity of cutting tools’ flanks made from cemented carbide, cermet and tool ceramics.