Silicon-based polymers containing nitrogen, carbon and boron have been considered as precursors for various non-oxide ceramics such as silicon carbide (SiC), SiCN and SiBCN.
These ceramics can be easily shaped using various forming processes and then cross-linked by exposure to heat or radiation to form an infusible solid. The consolidated preceramic polymers are finally pyrolyzed at high temperature to transform into the dense ceramic phases. These materials can be used for high temperature applications in areas such as electronic devices and structural composites.
Table 4.1 shows some selected important preceramic polymers that have been studied in various aspects. The polymers such as polysilanes, polycarbosilanes, polysilanzane, polysiloxanes are good candidates for ceramic phases due to their high ceramic yields on account of the combination of cross-linking and pyrolysis. Commercially available polysilazane (VL-20, KiON Corp., USA) and two types of polycarbosilane (Starfire System, USA and Nippon Carbon Co., Ltd., Japan) are readily used as preceramic polymers for SiCN and SiC ceramics, respectively.