Nitride and Oxynitride High Performance PVD Hard Coatings with Laser-processed Surfaces

This dissertation contributes to a better understanding of the laser processing of hard coatings deposited by means of physical vapor deposition (PVD). In the first part, a CrAl-based nitride coating is investigated, which was treated with continuous wave (CW) laser irradiation in order to achieve a high, exclusively thermal load, impacting the coating from the surface. The coating is extensively investigated with regard to the microstructure, morphology, phase stability and crystallinity. In the second part, three CrAl-based hard coatings with different chemical compositions are investigated, which were laser structured by means of ultra-short pulse lasers (USP) in the picosecond range under identical conditions to generate interference structures. The focus is on material properties concerning the incoupling of the laser irradiation, the ability to store thermal energy and the thermal conductivity. It is proven that the hard coatings considered here are laser-structurable in the sub-micron range by means of USP without crack formation and with high quality of the generated structures. The phase stability of the coatings is proven nearly up to the surface of the structures. Chemistry dependent differences of the generated structures are described in detail. The technical suitability of laser-structured hard coatings is proven in industrial injection molding for the production of polycarbonate (PC) parts. The successful transferability of the laser structures from the tool surface to the plastic components is qualitatively determined by means of the optical-functional effect of the interference colors.