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DS: Fachverband Dünne Schichten

DS 34: Hard and Superhard Coatings

DS 34.4: Vortrag

Donnerstag, 28. Februar 2008, 16:30–16:45, H 2032

AlCrVN - Design of high-temperature low-friction hard coatings — •Robert Franz¹, Jörg Neidhardt¹, Markus Lechthaler², Peter Polcik³, and Christian Mitterer¹ — ¹Christian Doppler Laboratory for Advanced Hard Coatings at the Department of Physical Metallurgy and Materials Testing, University of Leoben, Austria — ²Oerlikon Balzers Coating AG, Balzers, Principality of Liechtenstein — ³Plansee Lechbruck GmbH, Lechbruck, Germany

As environmental and economical considerations favour cutting with reduced coolants, controlling the friction becomes a major issue for the development of wear protective tool coatings. Common state-of-the-art coatings like AlCrN exhibit a relatively high friction especially at elevated temperatures, which leads to even higher thermal loads at the cutting edge and consequently to failure by thermal degradation. The incorporation of V into AlCrN results in a distinct reduction of the coefficient of friction at 700^∘C as the lubricious oxide V₂O₅ is formed. The new Al_xCr_yV_zN coatings were synthesised by means of physical vapour deposition using an industrial-scale arc-evaporation system. The desired metastable face-centered cubic (fcc) structure was stabilised even at an Al concentration of x=0.7 by using higher energetic growth conditions. Due to this structural evolution hardness and residual stress values comparable to fcc-AlCrN were retained. Annealing experiments in ambient air at temperatures ranging from 550-700^∘C revealed the formation of a V-rich oxide scale due to the immiscibility of V₂O₅ with the other oxides formed (Al₂O₃ and Cr₂O₃).