THERMAL PLASMA SYNTHESIS OF ALUMINUM NITRIDE.

Summary form only given, as follows. A thermal plasma reactor has been constructed for the synthesis of ceramic materials. Aluminum nitride has been synthesized by evaporation of the aluminum anode of a free-burning nitrogen plasma arc. An atmospheric nitrogen plasma which is stabilized by a shrouding nitrogen gas is operated at currents above 100 A. Aluminum evaporated from the anode reacts with nitrogen at a maximum reaction rate in temperature around 3500 K and the reaction product is collected from the water-cooled reactor wall. The collected product is photographed by a scanning electron microscope and the size distribution of the particles is evaluated by an image processing system. The average size of the particles is 300 angstrom, evaluated from 2000 particles. The purity of aluminum nitride has been also investigated with X-ray diffraction.