Silicon carbide, conventional method preparation

The conventional production method for SiC - the reaction of coke and sand (Acheson process) -does not involve soluble or fusible intermediates. For many applications of silicon carbide this fact is not necessarily a disadvantage, but for the preparation of ceramic composites such intermediates are required. 

Silicon carbide, SiC (i), and silicon nitride, Si3N4 (2), have been known for some time. Their properties, especially their high thermal and chemical stability, their hardness, and their high strength, have led to useful applications for both of these materials. The conventional methods for the preparation of SiC and SiaN4, the high-temperature reaction of fine-grade sand and coke (with additions of sawdust and NaCl) in an electric furnace (the... 

A new preparation method is described to synthesize porous silicon carbide. It comprises the catalytic conversion of preformed activated carbon (extrudates or granulates) by reacting it with hydrogen and silicon tetrachloride. The influence of crucial convoaion parameters on support properties is discussed for the SiC synthesis in a ftxed bed and fluidized bed chemical vapour deposition reactor. The surface area of the obtained SiC ranges ftiom 30 to 80 m /g. The metal support interaction (MSI) and metal support stability (MSS) of Ni/SiC catalysts are compared with that of conventional catalyst supports by temperature programmed reduction. It is shown that a Ni/SiC catalyst shows a considnable Iowa- MSI than Ni/Si(>2- and Ni/Al203-catalysts. A substantially improved MSS is observed an easily reducible nickel species is retained on the SiC surface after calcination at 1273 K. 

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