Fundamental investigations on the pre-process and in-operando oxidation of triboactive hard thin films

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In the proposed research project, a basic understanding of the relationships of atomic structure, microstructure, oxidation resistance and frictional behavior of Al-rich sputtered AlCrVY(O)N thin films is to be obtained. For this purpose, the thin films are deposited by means of magnetron sputtering on a WC-Co substrate, of which many tools consist. The aim is the deposition of AlCrVY(O)N coatings, which form self-lubricating vanadium oxide phases, so-called Magnéli phases, at elevated temperatures of 500°C to 1000°C, which significantly reduce the coefficient of friction. At the same time, it is of great importance that the known positive mechanical properties of the AlCrN coatings are maintained at these high temperatures. However, pure AlCrN thin films are not suitable for tribological and, in particular, friction-minimizing applications due to an increased coefficient of friction at elevated temperatures. The central aspect is the analysis of the influence of the pre-oxidation during the thin film synthesis on the tribological properties as well as the change of the oxide phases during use in laboratory scale. In comparison, oxygen-free AlCrVYN thin films are also produced and compared. For this purpose, the temperature-induced change in the structure of AlCrVY(O)N thin films, which are synthesized using different energetically high deposition methods, are investigated by means of X-ray diffraction (XRD) and X-ray absorption near-edge structure spectroscopy (XANES) using synchrotron radiation on the macroscopic and atomic scale with respect to oxidation formation of vanadium phases and oxidation resistance of the Al and Cr phases. The aim is the basic understanding of the influence of the deposition parameters and the pre-oxidized state on the structural effects of the coating properties and thus the possibility to develop friction-minimizing coatings with good mechanical properties at high temperature applications.