(39d) Fine Polycarbosilane Particles for Precursors of Silicon Carbide Ceramics Synthesized by Precipitation Processing in Solvents

Precursor-derived ceramics are fabricated by pyrolysis of preceramic polymers. Precursor processing enable to design the structure on an atomic scale, which is attractive for synthesizing advanced ceramic materials. On the other hand, various liquid processes to synthesize nano-sized polymer particles have been developed in fields of polymer technology. Such liquid processes are expected to be applied for polymer precursors of ceramics. In this study, chemical processing to form fine polymer particles based on dissolution and precipitation in solvents was investigated, in order to synthesize fine precursor powders for silicon carbide. The preceramic polymer used in this study was a commercially available polycarbosilane (PCS). The PCS polymer was dissolved in n-hexane. Then, the PCS solution was mixed into ethanol which was stirred with a magnetic stirrer. As the result, white precipitates were formed immediately. The precipitation is attributed to supersaturation of the PCS polymer by the dilution with the ethanol. The resulting precipitates were dried in a laboratory furnace. The scanning electron microscope observation showed that the obtained powder had very fine primary particle size of less than 100 nm, although these particles were aggregated. The dried powder can be converted to ceramic powder by cross-linking and pyrolysis treatments.