*N. Jäger¹, S. Spor¹, M. Meindlhumer¹, H. Hruby², C. Mitterer^1,3, J. Keckes,¹ R. Daniel^1
1Montanuniversität Leoben, Leoben, Austria; ²Vacotec GmbH, Düsseldorf, German;³Austrian Academy of Sciences, Leoben, Austria
Increasing demands on tool surface protection in machining industry towards advanced applications stimulate the development of coatings with enhanced properties. Besides substantial requirements on mechanical properties, also thermal stability and oxidation resistance play a key role in high-temperature applications. One approach for novel, thermally and mechanically stable materials is based on the development of coatings with complex architectures, such as nanocomposites or multilayers. In this work, arc-evaporated AlCrSiN-based coatings with varying Al/Cr ratio and Si content were deposited. By a careful control of the elemental composition and selection of the deposition conditions, thermal stability and oxidation resistance of the coatings were increased, predominantly by a formation of a nanocomposite structure. The subsequently suppressed decomposition of metastable phases resulted in an increase of thermal stability with a preserved hardness of >30 GPa up to 1100 °C. Another design strategy focused on the combination of a hard nanocomposite AlCrSiN phase with elastic inter-layers in a multi-layered architecture to increase the fracture toughness while preserving the high hardness. With this approach, the cutting performance was enhanced by 130% during dry milling of hardened steel. The results suggest a high potential of this microstructural design strategy for a variety of industrial high-temperature applications.