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M. Horkel, H. Mahr, J. Hell, C. Eisenmenger-Sittner, E. Neubauer:
"Determination Of The Thickness Of Metal Coatings On Granular Diamond Materials By Spatially Resolved Optical Methods";
Poster: 12 th Joint Vacuum Conference, 10 th European Vacuum Conference, 7 th Annual Meeting of the German Vacuum Society, Balatonalmadi/Ungarn; 22.09.2008 - 26.09.2008.

Embedding surface modified granulates into metallic matrices is a promising way to optimize the interface matrix/granulate in respect to mechanical and thermal properties. The surface modification of the granular material may be achieved by treating it by e. g. chemical agents, subjection to plasmas or by coating.
In the case of coating a reliable determination of the coating thickness on granulates is desirable since the interface properties may critically depend on it. In this paper we propose a simple method to determine the thickness of transparent metal coatings on diamond substrates.
Diamond granulates with grain sizes of 50 - 200 µm were coated with molybdenum in a specially designed device which allows reasonable film uniformity on granulates by subjecting it to continuous intermixing. The deposition method was single source DC magnetron sputtering with Ar as working gas.
After the transmission of uncoated diamonds was determined by an optical scanner (Reflecta CrystalScan 7200 working in transmission mode, software Silverfast AFL-SE), the same procedure was applied to the Mo coated diamonds. From the differences in optical density the film thickness of the Mo layer could be measured after the extinction coefficient of Mo was determined.
A good match with the film thicknesses calculated from the deposition time and the known erosion rate of the sputter source was achieved. A high coating uniformity could be achieved. Therefore it can be concluded that the presented method is a viable and cost efficient way to determine the thickness of transparent metallic coatings on transparent granular substrates, especially if it is connected to a pattern recognition software which would allow the treatment of larger granulate samples.
The financial support of the Austrian "Fonds zur Förderung der Wissenschaftlichen Forschung" (FWF), Grant No. P-19379-N16 is gratefully acknowledged.