Defects are one of the major obstacles in application of hard coatings. The corrosion resistance on these spots is severely reduced and the possibility of delamination is increased. We have analysed defect concentration by using statistical approach and by studying morphology, microstructure and composition of individual defects. We analyzed the composition on the spot of the defect and microstructural properties and found out that there are three types of defects: (i) pieces of foreign material, covered by the growing coating – they are a consequence of dust and delamination from chamber walls, (ii) microdroplets, covered by the growing coating with a porous microstructure, (iii) depressions, formed after delamination of the defects, Studies further revealed that defects originate either from inclusions in the substrate (e.g. sulphur inclusions found in different tool steel) or from deposition process itself. Both origins are important in all PVD techniques although process conditions normally dominate. In the deposition process, different stages, i.e. pump-down, heating, deposition and cool-down, cause formation of defects.
B.04 Guest lecture
COBISS.SI-ID: 26807335TiAlN/a-CNx double layer coating combines the advantages of a very hard, thermally stable TiAlN with the sliding and lubricating properties of the top a-CNx layer. The tribological performance of such coating strongly depends on the deposition method and deposition parameters. In this work we present the tribological properties of TiAlN/a-CNx coating prepared by sputtering in CC800/9 sinOx ML deposition system on tool steel and cemented carbide substrates. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectrometry and glow discharge optical emission spectrometry (GDOES) were employed for its microstructural, structural and compositional characterizations. Mechanical properties of the coated samples were characterized by indentation test (Vickers hardness), scratch tests (adhesion), atomic force microscopy, 3D-profilometer (topography) and pin-on-disk test (coefficient of friction and wear). We also tested different types of tools (tools for metal powder compaction, deep drawing of stainless steel, fine blanking) coated with TiAlN/a-CNx in industrial conditions. A significant improvement of tool lifetime was obtained).
B.04 Guest lecture
COBISS.SI-ID: 27362343