Abstract: A process for the manufacture of high purity, ultra-fine aluminum nitride powder by the carbo-nitridization of alumina. Agglomerates uniform in both size, chemical composition and porosity are formed containing a stoichiometric mixture of alumina and carbon with the addition of a small amount of catalyst. The agglomerates are furnaced in a controlled manner in a well-mixed reaction vessel to achieve a uniform and consistent level of conversion. Milling of the as-reacted agglomerates under a controlled atmosphere will produce high purity, micron sized aluminum nitride powder.

Abstract: A process and apparatus for the manufacture of high purity, ultra-fine aluminum nitride powder by the carbo-nitridization of alumina. In the method, agglomerates uniform in both size, chemical composition and porosity are formed containing a stoichiometric mixture of alumina and carbon, and a small amount of catalyst, and furnaced in a controlled manner in a well-mixed two chamber reaction vessel having optional top or bottom fluidizing gas feed to achieve a uniform and consistent level of conversion. Milling of the as-reacted agglomerates under a controlled atmosphere will produce high purity, micron sized aluminum nitride powder. The reactor is an automatically controlled fluid bed reactor for treatment of refractory materials with a hot fluidizing gas having a two chamber design in which the lower furnace chamber and reactor bed are removable from the bottom of the reactor. With unique reactor, unusually high reaction temperatures of up to 2000.degree. C. are obtainable.

Abstract: A fluid bed reactor for treatment of refractory materials with a hot fluidizing gas and a method to use same. Both the refractory materials and the fluidizing gas are introduced from the top of the reactor. Unusually high reaction temperatures of up to 2000.degree. C. are maintained in the reaction chamber due to the presence of heating elements within the reactor and due to countercurrent heat transfer.

Abstract: A furnace for the sintering of refractory or ceramic materials using plasma heated gases. The furnace comprises a sintering chamber with strategic positioning of the plasma torch inlets and exhaust outlet, a furnace temperature controlling device during sintering so that the article being sintered does not decompose. The devices which can be used for controlling the temperature of the furnace during sintering include: (1) Tangential injection of a secondary colder gas stream into the hot primary plasma gas stream; (2) Utilization of a plasma torch or torches which can be temperature controlled to achieve stable and lower plasma gas temperatures; and (3) Introduction of a secondary cooler gas directly into the furnace sintering chamber.

Abstract: A process for the sintering of silicon carbide refractory or ceramic articles using plasma arc gases. In the process of the invention, a formed silicon carbide article is heated in a plasma fired furnace to a sintering temperature of between 2000.degree. C.-2500.degree. C. at a heating rate of 300.degree. C./hr-2000.degree. C./hr, and held at the sintering temperature for 0.1-2 hours. The enthalpy of the plasma gas is 2000 BTU/lb-4000 BTU/lb, when nitrogen is used as the plasma gas. The total cycle time for the process of the invention, including cooling and loading, is 1.5-20 hours. Silicon carbide articles, produced in accordance with the invention, have high strength, high density, high corrosion resistance and high dimensional stability.

Abstract: An improved process for sintering extruded powder shapes comprising drying or calcining an extruded shape in a microwave furnace and rapid sintering the shape in a plasma fired furnace. Alternatively, calcining or drying may take place within a furnace heated by the plasma furnace's exhaust. The process of the invention is especially useful for silicon carbide extruded materials and for tubular shapes. This process significantly reduces sintering times and costs. Use of the process yields a high strength sintered product.

Abstract: A process for sintering or reaction sintering ceramic or refractory materials with hot plasma gases. The hot plasma gases are produced by injecting a combined primary plasma arc with a secondary gas stream directly into a reaction furnace. The secondary gas stream is tangentially injected into the primary plasma arc gas stream to mix the gases for the required sintering temperature at the highest energy efficiency. The plasma torches are positioned in the furnace ports so that the plasma gas flow is perpendicular to the furnace process gas flow. This process is inexpensive and efficient and results in a superior quality sintered product. It may be adapted to continuous or periodic kilns to achieve a high furnace productivity.