SYNTHESIS AND CHARACTERIZATION OF NEW PRECURSORS TO NEARLY STOICHIOMETRIC SIC CERAMICS .2. A HOMOPOLYMER ROUTE

An original route to SiC ceramics possessing low free carbon (similar to 3.8 at%) and oxygen (similar to 1 at%) contents is reported. It con sists of the polycondensation of 2,4-dichloro-2,4-disilapentane, prepa red by Grignard reaction of dichloromethane on methyldichlorosilane. T he undesired remaining chlorine was eliminated via a subsequent reduct ion using lithium aluminum hydride. The synthesis of the ceramic precu rsor was achieved by thermolysis under argon at atmospheric pressure, with the evolution of hydrogen and methane. The pyrolysis of the precu rsor provided SiC ceramics in an excellent yield (approximate to 79%).