Influence of silicon sources on structures and properties of polyborosilazane precursor derived SiBNC ceramic fiber

Different kinds of polyborosilazane(PBSZ) precursors for SiBNC ceramic fibers were synthesized by SiCl4/HSiCl3/HSiMeCl2 with BCl3 and NH3CH3 via a one-pot method, respectively. FT-IR NMR, TG, and DSC were employed to study the influence of silicon sources(SiCl4/HSiCl3/HSiMeCl2) on chemical structures and physical properties of PBSZ precursors. FT-IR and NMR results indicated that these three kinds of PBSZs have similar chemical structures, which were mainly composed of Si-N bonds and B-N bonds in the backbone(linkage through-N(CH3)-bridges). The spinning behavior of the PBSZ precursors was also investigated. The results showed that PBSZ synthesized by HSiMeCl2 had the lowest glass-transition temperature and better melt spinnability. PBSZ synthesized by SiCl4 had the highest ceramic yield. Moreover, PBSZ synthesized by HSiCl3 was the most suitable candidate to produce SiBNC ceramic fibers, and the obtained SiBNC ceramic fibers exhibited good high-temperature stability which could keep its amorphous state at 1600 degrees C.