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Progress in Plasma Processing of Materials, 2003

ISBN:
978-1-56700-192-1 (Print)
978-1-56700-447-2 (Online)

REDUCTION OF TUNGSTEN PRECURSORS IN INDUCTIVELY COUPLED RF DISCHARGE

Marek Elias
Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37 Brno, Czech Republic

Jan Janca
Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37 Brno, Czech Republic

J. Zila
Department of Physical Electronics, Masaryk University Kotlarska 2, 611 37 Brno, Czech Republic

Vlastimil Brozek
Institute of Chemical Technology, Technicka 5, CZ-16628 Prague; Institute of Plasma Physics, ASCR, Za Slovankou 3,182 00 Prague 8

Abstract

The intention of our experiment was to reach the synthesis of catalytically active tungsten carbide compounds with the aid of plasmachemical reaction at temperatures between 800 and 900 K. We studied the process with respect to kinetics as well as economic point of view. Optimistic expectations are raised by favourable results with paratungstate (APT) precursors reduced in a hydrogen plasma concentrated on the surface area, this process leading to an increase of sinterability of tungsten powder. For the reaction of APT with mixed propane/butane and hydrogen plasma we used a low pressure inductively coupled plasma (ICP). We observed that the powder was a mixture of tungsten and tungsten carbide. The percentage of tungsten carbide in the powder was influenced by reduction conditions (flow rate of hydrogen and propane/butane, time of reduction). The maximum percentage was about 6 %. Tungsten with grain sizes of 50 µm had a specific surface of 9 m2/g. It means that the grains were very porous.