Preceramic Polymer Blends as Precursors for Boron-Carbide/Silicon-Carbide Composite Ceramics and Ceramic Fibers

Simple blends of the poly(norbornenyldecaborane) (PND) boron-carbide preceramic polymer with either of the commercial poly(methylcarbosilane) (PMCS) or allylhydridopolycarbosilane (AHPCS) silicon-carbide preceramic polymers have been found to provide excellent processable precursors to boron-carbide/silicon-carbide ceramic composite materials. The blends exhibited good char yields with tunable ceramic compositions. Certain compositions of the PND/AHPCS derived ceramics also exhibited significant oxidation resistance. Nonwoven mats of PND/PMCS polymer composite fibers were readily obtained by the electrostatic spinning of polymer blend solutions. The pyrolytic ceramic conversion reactions of the PND/PMCS polymer fibers then produced mats of micro- and nanodiameter boron-carbide/silicon-carbide ceramic composite fibers.