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Proceedings Paper

Reduction of aluminum, silicon, and boron oxides in a carbon plasma of pulsed-power microwave discharge
Author(s): Alexander A. Ravaev; Iskander K. Tagirov; Pavel S. Chernyshev
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Paper Abstract

The high stability of aluminum, silicon and boron oxides is well known. A thermodynamic analysis of usual reactions of a carbon reduction of these oxides indicates that a degree of their conversion is quite low: for example, less than 0.3% for the alumina reduction at temperatures approximately equals 1900 K. On the other hand, a high efficiency of plasma-chemical processes and advantages of the user of microwave produced plasmas for materials processing are not a secret too. It was very interesting, from this viewpoint, to conduct mentioned reactions in a plasma of the pulsed power microwave (PPMW) discharge. Experiments were carried out in the focal zone of a focused PPMW beam at intensities up to 5 X 104 MW/cm2 (wavelength - 4 cm, pulse duration - 1...1000 microsecond(s) , repetition rate - 10 Hz). Quartz retorts containing powdered mixtures of outlined oxides with stoichiometric quantities of a carbon-black were pumped down to initial pressures of approximately equals 1 Torr. During the plasma treatment the pressure inside retorts grew and reached values of 100-200 Torr. After that retorts were pumped down again, and the process was continued. The total time of powders processing was of 20-60 min, and the samples' temperatures did not exceed 1300 K. Thus, for example, at the time of reduction of mixtures Al2O3 + C in amounts of 2 g, about 0.3 'normal' liters of gases were evolved, that corresponds to approximately equals 30% degree of the alumina conversion. Simultaneously, a strong influence of the steamer-like PPMW discharge in the atmosphere outside retorts on the reduction process was observed. Obviously, the reactions proceed at a higher rate due to the inducing role of a intense UV- radiation of such discharges. It is an important practical result too.

Paper Details

Date Published: 3 March 1995
PDF: 9 pages
Proc. SPIE 2374, Novel Applications of Lasers and Pulsed Power, (3 March 1995); doi: 10.1117/12.205005
Show Author Affiliations
Alexander A. Ravaev, Moscow Radiotechnical Institute (Russia)
Iskander K. Tagirov, Moscow Radiotechnical Institute (Russia)
Pavel S. Chernyshev, Moscow Radiotechnical Institute (Russia)


Published in SPIE Proceedings Vol. 2374:
Novel Applications of Lasers and Pulsed Power
Michael W. Prairie; Randy D. Curry, Editor(s)

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