AVS 52nd International Symposium
    Advanced Surface Engineering Monday Sessions
       Session SE-MoM

Paper SE-MoM4
Columnar Growth, Nanostructure and Properties of TiC/a-C:H Nano-Composite Coatings

Monday, October 31, 2005, 9:20 am, Room 201

Session: Nanocomposites and Coatings with Enhanced Thermal Stability
Presenter: D. Galvan, University of Groningen, The Netherlands
Authors: D. Galvan, University of Groningen, The Netherlands
Y.T. Pei, University of Groningen, The Netherlands
J.Th.M. De Hosson, University of Groningen, The Netherlands
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TiC/a-C:H coatings were deposited through closed field unbalanced magnetron sputtering (CFUBMS) reactive deposition. Different acetylene gas flow and substrate bias values were employed to vary the coatings composition and nanostructure. To improve adhesion between substrate and coating a Cr-Ti/Ti-TiC graded interlayer was introduced. Various techniques were employed to study the formation of TiC particles within the a-C:H matrix, e.g. EPMA, XPS, grazing angle XRD and high-resolution transmission electron microscopy (HR-TEM). The investigations provide detailed information about the TiC particles volume fraction, particle size and their size distribution in different coatings. It turns out that the Ti content affects to a great extent the columnar features. It is influenced by processing parameters such as deposition temperature or ion flux to atom flux ratio (ion number). An explanation of this effect is provided based on the observed nanostructure and the deposition technique employed. The mechanical performance of coatings with various chemical compositions was investigated through nano-indentations, focused ion beam (FIB) and TEM observations. It was found that the C-enriched columnar boundaries are the locations of crack nucleation and propagation. The investigations confirmed that a coating of low elastic modulus favors the redistribution of the applied load over a larger area, delaying the onset of plastic deformation and subsequent coating failure in these systems. The influence of the toughness of the coatings on their tribological performance is discussed.