New approaches to plasma enhanced sputtering of advanced hard coatings

PVD coatings and cutting tool materials experienced a rapid development in the past due to the increased demands of modem, innovative HPC (High Performance Cutting) production processes. The development of new materials progressed so rapidly that it is partly not known, how these materials can be economically processed with respect to measures of reducing costs and thus increasing productivity. In order to meet the different requirements a range of developments have been brought forward in the area of coating technology. Al2O3 was and still is an important component of conventional coatings. Especially the different crystalline modifications synthesized by CVD have gained considerable economic significance. Distinct chemical resistance, higher hot hardness and less interaction with almost all production relevant materials than most hard coatings are the main success factors of Al2O3 films. Within the first step the plasma enhanced PVD technology for the deposition of ternary coatings with higher aluminum content was developed. These films continuously generate a protective crystalline alumina layer at elevated temperatures. In addition to RF- and DC-sputter sources, pulsed plasma sources are gaining increased attention in sputter technology. This interest is driven by the significantly enhanced ionization of pulsed plasmas as compared to conventional DC and RIF techniques. Using highly ionized plasmas the High Ionization Sputtering (H.I.S.) and the High Ionization Pulsing (H.I.P.) processes have been developed to deposit a novel grade of high performance hard coatings, the supernitrides. The present paper provides a survey of latest approaches to plasma enhanced sputtering and related coating systems, with regard to the demands of high performance applications.