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C. Eisenmenger-Sittner, E. Neubauer, C. Schrank, B. Schwarz:
"PVD FILM GROWTH, WETTING AND ADHESION ON DISORDERED SURFACES AND COMPLEXLY SHAPED BODIES";
Vortrag: Workshop on Reactive Sputter Deposition, Ghent, Belgien (eingeladen); 30.11.2006 - 01.12.2006.

PVD FILM GROWTH, WETTING AND ADHESION ON DISORDERED SURFACES AND COMPLEXLY SHAPED BODIES

C. Eisenmenger-Sittner, E. Neubauer*, C. Schrank, B. Schwarz
Institute of Solid State Physics, Vienna University of Technology, Vienna, Austria
*ARC Seibersdorf Research, Dept. Materials Research, A-2444 Seibersdorf

Thin film deposition by Physical Vapor Deposition (PVD) is commonly used as a technique to coat plane, well defined substrates of areas ranging from square centimetres to square meters. Nonetheless, new developments in materials science introduce PVD methods in fields where they have not been commonly used previously. These fields include the material class of short fiber- and granulate re-inforced materials such as Metal Matrix Composites (MMC's).

An example are short fiber (approx. 0.5 mm length and 10 µm diameter) Copper Carbon MMC's which are potential materials for heat sinks in high performance electronic components and fusion applications. A crucial point is the improvement of the interface between Cu and C in respect to adhesion and Thermal Contact Resistance (TCR). This can either be accomplished by the direct deposition of Cu by magnetron sputtering on plasma treated C-surfaces and/or by the deposition of intermediate layers on the C-surface.

In the first part of this talk a basic description of Carbon based granular materials with a special emphasis on Carbon fibers will be given. Their bulk and surface structure will briefly be discussed. Some concepts of coating granular and fibrous materials with PVD methods, especially by magnetron sputtering, are presented.

The second part deals with the thorough analysis of the interface between the disordered C-surface and a sputter deposited Cu coating. The C surface is either modified by a Nitrogen Radio Frequency (N2-RF) plasma pre treatment or by the deposition of a Mo interlayer of approx. 100 nm thickness. Special emphasis is given to the influence of a post-deposition treatment (60 minutes at 800°C under HV-conditions) on the evolution of crystallography, surface- and bulk morphology, wetting, adhesion and stress within the Cu-coating. All these properties are intimately related both, to the substrate surface and to the initial structure of the sputter deposited coating.

In the third and final part the issue of the transfer of data which are obtained from limited regions of the interface to the whole C-fiber and, finally, to a complete MMC is discussed. It is shown that even results obtained from plane substrates can readily be transferred to the complex case of a thermally compacted composite material as it is shown by thermomechanical measurements on different composite materials.