Manufacturing Processes for Silicon Carbide

Silicon carbide is manufactured industrially by the electrochemical reaction of high purity quartz sand with carbon in an electric resistance furnace (Acheson process)  

Industrial manufacture of SiC is carried out using the Acheson process by reacting SiOi with carbon in an electric furnace 

Preferred carbons are petroleum coke (pitch coke) and anthracite. Addition of sodium chloride ensures the removal of troublesome impurities as volatile chlorides. The presence of sawdust increases the porosity of the reaction mixture and eases outgassing. 

Silicon carbide occurs in a large number of different crystal structures 

The electric furnaces, in which this reaction is carried out, are ca. 15 3 3 m- in size and are lined with refractory material. Electrodes at opposite ends are connected to a graphite core. The furnace is filled round this core with the reaction mixture and electrically heated to 2200 to 2400°C. The heating up time is ca. 18 h and the reaction time a further ca. 18 h. After cooling, the sides of the furnaces are removed and the unreacted material on the edges removed. The silicon carbide, which has formed round the graphite core, is broken up and separated into different qualities. 

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Manufacturing process for silicon carbide whiskers by VLS from rice husk (reproduced by permission of Chapman Hall)56. 

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