THE THERMAL-BEHAVIOR OF POTENTIAL POLYMERIC PRECURSORS FOR SILICON-CARBIDE FIBERS

As silicon carbide fibres cannot be manufactured by conventional methods, alternative fabrication routes must be found. One such is the polymeric precursor route. The production of polysilanes via the alkali dechlorination route is described, as is the effect of varying the functionality f of the starting monomers or the overall functionality F of the product. To produce a silicon carbide fibre, the polysilane must be separated into suitable fractions, the soluble solid fraction has to be spun into a fibre and the product eventually pyrolysed to a ceramic material. In this paper the advantageous use of thermomechanical analysis (TMA) to determine a spinning temperature is described and also the use of derivative thermomechanical analysis (dTMA). The determination of the potential ceramic yield by the use of thermogravimetry (TG) is also discussed.