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This paper deals with the time resolved optical emission spectroscopy (OES) of a high power pulse magnetron sputtering (HPPMS) physical vapor deposition (PVD) coating process. With an industrial coating unit CC800/9 HPPMS (CemeCon AG, Würselen) a (Cr,Al,Si)N coating was deposited. During the coating process, an absolute calibrated Echelle-spectrometer (ESA-3000) measured the intensities of the spectral lines of Chromium (Cr), Aluminum (Al) and molecular bands of nitrogen (N 2). Time resolved measurements enable us to calculate different parameters like the average velocity of sputtered Al-and Cr-atoms or the internal plasma parameters electron density n e and electron temperature kT e with a time resolution of 20 µs. With these parameters, we determine the ionization rates of Al-, Cr-, Ar-and Kr-atoms and the deposition densities of Al-and Cr-atoms. Thus simulated deposition densities of 1.75 • 10 20 m −2 s −1 for Chromium and 1.7 • 10 22 m −2 s −1 for Aluminum are reached.

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Cutting of Ni alloys such as Inconel 718 or austenitic stainless steel is one of the greatest challenges in high-speed machining because of low thermal conductivity, the tendency to strain hardening, and adhesion on the cutting tools, resulting in high tool wear and high thermal load on the cutting tool. However, these difficult-to-machine materials are increasingly employed. Therefore, cutting tools with a high oxidation resistance, a low tendency to adhesion-related sticking, high hot hardness, and high abrasion resistance are necessary. One of the promising candidates for these types of cutting operations is the crystalline g-alumina phase. It offers high hot hardness, high resistance against adhesion-related sticking, and high chemical and thermal stability at elevated temperatures. [1,2] The excellent performance of g-Al 2 O 3 for cutting operations has already been reported. [3] However, the unexpected thermal stability of the metastable g system as thin film has not been completely investigated and understood. Alumina is a polymorphous material and a-alumina is the only stable phase. In industrial processes, a-alumina is deposited by means of CVD (chemical vapor deposition at temperatures of 1000 8C. [4,5] These high temperatures reduce the choice of substrates. The deposition of g-Al 2 O 3 by means of PVD (physical vapor deposition) allows lower substrate temperatures (500-650 8C) and is therefore interesting for many applications. Besides the lower deposition temperature, the g-phase generated by PVD has some advantages over the a-phase generated by CVD: PVD-alumina coatings are smoother and have a smaller grain size. They therefore have a higher fracture toughness and strength. [6] Nevertheless, the working temperature of g-Al 2 O 3 has to be considered because of the transformation into the stable a-phase. We analyzed (Ti,Al)N/g-Al 2 O 3 thin films with common thin film test equipment. Furthermore, in situ annealing tests were performed to determine the thermal stability of the coating. To test the coating's performance for cutting operations, we compared (Ti,Al)N/g-Al 2 O 3 and a state of the art nanocomposite (Ti,Al)N as described in Reference [7] by pin-on-disk tests and turning tests. Experimental Details Deposition SetupNanocomposite (Ti,Al)N and alumina coatings were deposited on WC-Co cutting inserts. Two different inserts were chosen: THM 12, SNUN 120412 (Kennametal Holding GmbH) for characterization of the coatings and for tribological Crystalline PVD g-Al 2 O 3 -coatings offer great potential for their use in high-speed cutting operations. They promise high hot hardness and high oxidation resistance at elevated temperatures. This is important for coatings that are used for machining of materials with low thermal conductivity such as stainless steel or Inconel 718 because heat generated during cutting can barely be dissipated by the chip. Because of the prevailing bonding forces of alumina, adhesion-related sticking can be reduced even for dry cutting. Furthermore, the high formation enthalpy ...

Over the last decades demands for optical systems and complex optical products made of glass increased steadily. Precision glass moulding has a great potential for the bulk production of complex lenses with high precision and low costs. To prevent sticking or reactions between hot glass and moulding, and to reduce abrasive wear of the die a protective coating is deposited on the tool. In this research two coating systems suitable for this application are compared by analysing their behaviour under an impact load. The PVD (Physical Vapor Deposition) coating PtIr with two different bond coatings Ni or Cr is analysed. During impact test number of impacts and loads are varied. Compared to industrially used coating system PtIr with a Ni interlayer the adhesion can be improved by using a Cr interlayer. The PtIr-based coating with Cr as bond coating shows an excellent endurance even at very high loads causing Hertzian stresses in the range of 10 14 GPa. An impact load of 600 N which corresponds to a contact pressure of app. 13.2 GPa generates almost no damage after 200,000 impacts.