General reactor design considerations and interpretations for the formation mechanism of several non-oxide ceramic powders are presented,as well as the possible chemical reactions involved in the processes under the high temperatures generated in a thermal plasma.Silicon carbide,titanium carbide,titanium diboride,zirconium carbide,titanium carbide-iron and boron nitride powders have been synthesized using oxides as precursors.For each ceramic system the precursors are vaporized completely in the hot zone of the reactor where the plasma source is located;the vapors then travel down the temperature gradient to meet conditions where specific chemical reactions may occur(with subesequent nucleation and/or growth); this is followed by rapid quenching to minimize back reactions or additional growth,thus enhancing the formation of metastable compounds that are consequently stabilized at room temperature.A description of the reactor system is presented along with theoretical and experimental results and conclusions from experiments.
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