MANUFACTURING APPARATUS FOR FINE POWDER OF SILICON CARBIDE, SILICON NITRIDE AND SILICON NITRIDE CERAMIC

摘要

PURPOSE:To mass-produce the titled fine powder of submicron grain size with a low free substance content in a high yield by installing a screw conveyor for continuously feeding a starting material mixture, a screw conveyor for discharging a product, and an agitation mixer for a mixture in a region between the conveyors in a reaction tube. CONSTITUTION:The driving shaft of an agitation mixer (b) is inserted in the hollow shaft of a screw conveyor (a) for conveying a starting material mixture. Screw conveyors (c), (d) ar inserted silimarly, and the bearing-shaped ends of the mixer (b) and the conveyor (c) are brought into contact with each other. They are set in a reaction tube 4 and rotated separately. A mixture introduced from a hopper 3 into the temp. zone A of the tube 4 under the reaction temp. in an electric furnace 11 is heated to 1,200-1,650 deg.C in a vacuum of 10mm.Hg or a rare gas or N2 atmosphere to cause a reaction. The mixtre is agitated and mixed in the zone B between the reaction start temp. and maximum temp. zones. It is further reacted in the zone C between the maximum temp. and reaction finish temp. zones, and taken out of the reaction stop temp. zone D as a reaction product. Thus, SiO vapor produced in the intermediate step can be prevented from escaping from the reaction system.