Silicon carbide, discovery

The discovery by Yajima that polysilanes could be pyrolyzed to silicon carbide was mentioned in the introduction.7 In this process, either (Me2Si) or the cyclic oligomer (Me2Si)6 are synthesized from Me2SiCl2 and are then heated to near 450 °C (Scheme 5.10). This discovery has been commercialized by the Nippon Carbon Co. for the production of NICALON silicon carbide fibers. In this process, methylene groups become inserted into many of the Si-Si bonds to give a polycarbosilane polymer with the idealized 5.14. 

The conventional industrial method for the synthesis of a-silicon carbide is to heat silica (sand) with coke in an electric furnace at 2,000-2,500 °C. However, because of the high melting point of the product, it is difficult to fabricate by sintering or melt techniques. Thus, the discovery of a lower temperature fabrication and synthesis route to silicon carbide by Yajima and coworkers in 197526,27 proved to be an important technological breakthrough. This is a preceramic polymer pyrolysis route that has been developed commercially for the production of ceramic fibers. 

F. V. Kekule interpreted benzene to be a cyclic entity in 1865. The concept of carbon as a tetrahedraUy, four-fold coordinated atom was presented independently by J. H. van t Hoff and J. A. Le Bel in 1874 and revolutionized the interpretation of the element s chemical activity (Figure 1.1). Since then, fundamental discoveries on this ubiquitous element multiplied. L. Mond and co-workers published the first metal carbonyls in 1890, and in 1891, E. G. Acheson for the first time achieved artificial graphite via intermediate silicon carbide (carborundum), which itself had been unknown then, too. 

Since the initial discovery of carbon nanotubes (CNTs) by lijima et al. [122], much interest has been expressed in developing other inorganic nanostructured particles, due to the unique properties assigned to these nanostructures. Indeed, many potential applications have been proposed for silicon carbide nanostructures, including high-strength composites, nanosensors, and nanodevices. 

Another example of a new field opened by Schutzenberger was the discovery of unusual inorganic compounds. His interest was related to possible substitutions between metals and metalloids. He made scientific studies on carbon and platinum, then on carbon and silicon, and obtained silicon carbide, silicon nitride and silicon oxycarbide. Once more, his research seems to have been undertaken for scientific reasons alone, and in this case no attention was given to technical applications. At least, no patent was applied for. ... 

These discoveries were followed by two key publications describiog the work that marked the beginning of the commercial silicone industry (18,19). Production increased rapidly with the need for silicones in World War II. In 1943, the Dow Coming Corp. was formed in Midland, Michigan, as a joint venture between Coming Glass and Dow Chemical. In 1947 GE opened a plant in Waterford, New York, for manufacture of silicones, and in 1949 Union Carbide opened a silicone manufactuong plant in Tonawanda, New York... 

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