Papers

ICMCTF2008 Session G1-1: Innovations in Surface Coatings and Treatments

Thursday, May 1, 2008 1:30 PM in Room Sunset

Thursday Afternoon

Start	Invited?	Item
1:30 PM		G1-1-1 Plasma Surface Engineering For Industrial Applications C.F. Ali (Institute of Nuclear Energy Research, Taiwan) The regulation of environmental protection worldwide is getting stricter and stricter. The exporting manufacturing industries in Taiwan are facing changes into cleaner production processes of green products and pressures of shifting toward high-quality niche market. The plasma surface engineering (PSE) is such a technology which could satisfy both needs for surface treatment industry and, for these purposes, the Institute of Nuclear Energy Research (INER) has collaborated with local industries in the applications of PSE for many years and the gained experiences including the novel processes and apparatus are to be reported in four categories. First, plasma enhancing coating: the hard films, such as TiN, TiC, TiAlN, ZrCN, CrN, Me-DLC etc., were deposited onto various substrate materials, especially for metallic sheets as large as 5 m by 1.5 m with varied colors. Second, plasma nitriding plus coating: spiral shafts for plastic injection were hardened deep into surfaces by plasma nitriding and then followed by plasma coating of hard films on the nitrided surface in situ to further enhance its mechanical properties. The aim is to mass process these shaft of at least 3 m length. Third, plasma surface activation: a low-temperature (< 40°C) and high-speed (>6 m/min) surface activation processor for PET rolled film substrate (1.2 m width) with a novel plasma reactor was developed to match with the subsequent mass-production coating process, such as ITO films for touch panel. Fourth, large area atmospheric glow discharges have been developed and is being used in the surface activation of polymer substrate, especially the textile polymers, with the following dual functional coatings ( hydrophilicity and hydrophobicity on different sides, respectively). In addition, many other novel applications with PSE are also to be mentioned in this presentation.
2:10 PM		G1-1-4 Surface Morphology of Low Alloy Steel Plates Treated by Electron Beam Excited Plasma Source P. Abraha, Y. Yoshikawa (Meijo University, Japan) The nitriding performance of low power electron beam excited plasma is investigated by characterizing the compound layer formed on the surface of nitrided low alloy Cr-Mo steel specimen. In an attempt to maximize the dissociation of N2, the acceleration voltages applied in our experiments were set within a range that corresponds to the maximum dissociation cross section of N2. In this experiment, a particular attention was given to the effect of the treatment time on the surface morphology, composition, and Vickers hardness of the treated specimen. The results show that the peak intensity of the alpha Fe observed for the untreated specimen decreased as the treatment time increased. Moreover, the peak intensities depicting the formation of the nitride compound layers, Fe4N and Fe3N phases, increased with the treatment time. Consequently, the surface hardness of the treated low alloy steel specimen was increased to 1010HV and a nitrided depth of up to 120µm was attained in 4.5 hours of treatment time.
2:30 PM		G1-1-5 TiAl(N,C,O) Black PVD Coating for Decorative Applications R.C.O. Constantin (HES-SO, SWITZERLAND); P.A. Steinmann, P.A. Gay (HE-ARC, Switzerland) PVD black coloured coatings represent a significant part of the market in the production of decorative coatings for watch making industry and jewelry. Most of these coatings are based on amorphous carbon (Diamond Like Carbon or DLC) made by PE-CVD or PVD, or titanium oxy-carbides (in a less extent) but they both suffer from some drawbacks which can limit their applications. In this study, TiAl (N,C,O) coatings have been deposited using a laboratory PVD and an industrial plant (Hauzer HTC 1000/4) and studied by different analytical, chemical and mechanical methods. The results show that by controlling the deposition parameters, it is possible to obtain deep dark coloured coatings with metallic brightness along with better wear resistance than conventional DLC coatings. EPMA and XPS analysis confirmed that the pitch black colour was put down to the incorporation of oxygen in the coating during TiAl deposition. Black shades obtained with a laboratory PVD installation quite differs from the deep black colors achieved with an industrial plant in which consequent outgazing occurs, leading to oxygen and carbon contamination in the coatings and the resulting formation of the desired black colour and the decrease of internal stresses while keeping relative high hardness. Real wear tests are currently in process; these tests are unfortunately often omitted by PVD companies but are still very important for final validation. After one year of real wear test, the coatings performed quite well and this confirms the excellent results obtained with laboratory tests.
2:50 PM		G1-1-6 Development of Black Ti(C,O,N) Coatings Prepared by Reactive Sputtering J.M. Chappé, F. Vaz (Universidade of Minho, Portugal); M.C. Marco de Lucas, O. Heintz, L. Imhoff, S. Bourgeois (Institut Carnot de Bourgogne, France); J.F. Pierson (Ecole des Mines, Laboratoire de Science et Génie des Surfaces, France); L. Cunha (University of Minho, Portugal) Dc reactive magnetron sputtering was implemented to successfully deposit black Ti(C,O,N) thin films on glass, steel and silicon substrates. A titanium target was sputtered while a mixture of oxygen and nitrogen was injected into the deposition chamber, independently from an acetylene source. The deposition parameters were chosen as a function of pre-existing knowledge about sputtered Ti-O-N and Ti-C-O films, tailoring their properties between those of TiN (or TiC) and TiO₂ coatings. Tuning the oxygen / (nitrogen + carbon) ratio allowed obtaining a large spectrum of different properties. The color of the films was characterized by spectral reflectance spectroscopy, and expressed in the CIE 1976 L^a^b^* color space. An accurate control of the reactive gas mixture flow rate allowed obtaining intrinsic, stable and attractive black color, for decorative applications. The coating with the highest content of carbon presented the most satisfying color. Composition analysis by electron probe microanalysis was done to quantify the titanium and metalloid concentrations in the films. X-ray diffraction experiments revealed the evolution of the film structure from a f.c.c. structure for the lowest (O₂ + N₂) flow rates to an amorphous for the highest flow rates. Raman spectroscopy was used to complete the structural characterization of the films. It revealed the increasing formation of amorphous carbon by increasing the (O₂ + N₂) flow rate. X-Ray Photoelectron Spectroscopy was also performed for studying the different chemical environments in the films. Finally, cross section images by scanning electron microscopy showed a very dense morphology for all the coatings.
3:10 PM		G1-1-7 Advanced Tribological Coatings - Prepared in Industrial Scale Machines K. Bewilogua, M. Keunecke, M. Weber, H. Thomsen, K. Weigel, R. Wittorf (Fraunhofer IST, Germany) Two different types of tribological coatings, both prepared by reactive sputtering techniques shall be considered: (i) hard amorphous hydrogenated carbon films (a-C:H and a-C:H:Me, containing transition metals), (ii) cubic boron nitride coatings. The hard amorphous hydrogenated carbon coatings were prepared in different large scale sputter coaters equipped with 4 targets, rotating substrate carriers and with electromagnetic coils. The coils caused high ion current densities at the substrates. The a-C:H coatings were deposited varying parameters like substrate bias, acetylene flow and coil currents. Process windows for superhard a-C:H coatings with hardness values up to 50 GPa could be achieved. To improve the adhesion of the a-C:H coatings different interlayers consisting of metals like Ti and Cr or of CrN or of a-C:H:W were prepared. Due to the substrate rotation a-C:H:W coatings had a pronounced multilayer structure. The films growth on 3-dimensional parts was markedly influenced by the geometric aspects. Furthermore, rough, not polished surfaces occurring at real components showed considerable growth irregularities. Because of their high hardness and thermal stability, cubic boron nitride (cBN) coatings are highly attractive for cutting tool applications. However, there are still some obstacles to overcome before cBN coatings will meet an industrial level. After more than 10 years development, today at least sufficiently thick cBN films (2 µm) can be prepared in a laboratory scale. The present state and the consequences in view of cBN deposition on 3- dimensional tools and to an up scaling to industrial machine dimensions will be discussed.
3:50 PM		G1-1-9 Wear Indicating Sensors of Rotating Tools O. Lemmer, R. Cremer (CemeCon AG, Germany); D. Hagedorn, F. Löffler (Physikalisch-Technische Bundesanstalt, Germany) An indication of the tool wear is of interest not only for the operating time optimisation of cutting tools but also for reducing the tool change time. For this indication a sensor will be build in a tool surface. The main task of the sensor is the recording of the wear amount. Conductor tracks or capacitive transducers are possibilities of sensor principles. After a theoretical discussion of various sensor structures some structures will be selected. The realisation will be done on tools or samples similar to tools. Milling cutter are selected as representatives of rotating tools and will be used as substrates for this study. Sputter processes will be used for coating operations and lithography will create the required structures. The layer material selection should consider the different tasks of the coatings. They have to be suitable for wear protection and for sensor applications. Metallographic analysing of the sensor will describe the achieved structure and quality. Application tests will give information of the usability of the sensors.