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Silicon carbide is produced in two steps in that silicon dioxide and a carbon source in a first step is reacted at a temperature in the range of 1500-1800.degree. C., whereby the silicon dioxide and the carbon source react to form .beta.-silicon carbide. The resulting .beta.-silicon carbide formed i

Silicon carbide is produced in two steps in that silicon dioxide and a carbon source in a first step is reacted at a temperature in the range of 1500-1800.degree. C., whereby the silicon dioxide and the carbon source react to form .beta.-silicon carbide. The resulting .beta.-silicon carbide formed is subsequently treated at a temperature of 1800-2300.degree. C. for conversion of the .beta.-silicon carbide into the desired end product, via .alpha.-silicon carbide.

대표청구항 ▼

[ We claim:] [1.] A process for the production of .alpha.-silicon carbide by reacting approximately stoichiometric amounts of silicon dioxide and a carbon source in a furnace at a temperature in the range of 1500-2300.degree. C. and ambient atmosphere, which process comprises a first step in which t

[ We claim:] [1.] A process for the production of .alpha.-silicon carbide by reacting approximately stoichiometric amounts of silicon dioxide and a carbon source in a furnace at a temperature in the range of 1500-2300.degree. C. and ambient atmosphere, which process comprises a first step in which the silicon dioxide and the carbon source are continuously fed to a furnace and reacted at a temperature in the range of 1500-1800.degree. C. forming .beta.-silicon carbide, and a second step in which the thus formed .beta.-silicon carbide continuously is withdrawn from said furnace and converted to .alpha.-silicon carbide by heat treatment at a temperature in the range of 1800-2300.degree. C. [6.] A process for the production of green .alpha.-silicon carbide in non-platelet form by reacting approximately stoichiometric amounts of a silicon source and a carbon source in a furnace at a temperature in the range of 1500-2300.degree. C., which process comprises a first step in which the silicon source and the carbon source are continuously fed to a furnace and reacted at a temperature in the range of 1500-1800.degree. C. forming .beta.-silicon carbide, and a second step in which the thus formed .beta.-silicon carbide is continuously withdrawn from said furnace and converted to green .alpha.-silicon carbide in primarily non-platelet form by heat treatment at a temperature in the range of 1800-2300.degree. C. [13.] A process for the production of .alpha.-silicon carbide by reacting approximately stoichiometric amounts of a silicon source and a carbon source in a furnace at a temperature in the range of 1500-2300.degree. C., which process comprises a first step in which the silicon source and the carbon source are continuously fed to a furnace and reacted at a temperature in the range of 1500-1800.degree. C. forming .beta.-silicon carbide, and a second step in which the thus formed .beta.-silicon carbide continuously is withdrawn from said furnace and converted to .alpha.-silicon carbide by heat treatment, without the use of platelet-enhancing materials or the flow of an inert gas through the furnace, at a temperature in the range of 1800-2300.degree. C. A process in accordance with claim 13, characterized in that step 1 is carried out in a closed furnace and gaseous reaction products are recovered. A process in accordance with claim 13, characterized in that step 1 is carried out in a rotating furnace heated by means of a plasma torch or an arc. A process in accordance with claim 13, characterized in that the silicon dioxide and the carbon source are fed to the furnace in the form of pellets. A process in accordance with claim 13, characterized in that step 2 is carried out in a shaft furnace or an "Acheson" furnace. A process in accordance with claim 13 in which the silicon source is in the form of quartz sand and the carbon source is in the form of petrol coke.