Preparation of hybrid polymer as a near-stoichiometric SiC precursor by blending of polycarbosilane and polymethysilane

A hybrid polymer as a near-stoichiometric SiC precursor was prepared by simply blending polycarbosilane (PCS) as a carbon-rich SiC precursor and polyborazine-modified polymethylsilane (M-PMS) as a silicon-rich SiC precursor at an optimized ratio of 0.25:1.00 (PCS:M-PMS) by weight. The hybrid precursor showed a very high ceramic yield of 82 wt.% and higher molecular weight than that obtained using a single precursor. The excellent processibility of the hybrid precursor was proven by dry-spinning it into green fibers. Based on XRD, C-13 MAS-NMR and Si-29 MAS-NMR measurements, the SiC ceramic derived from the hybrid precursor at 1400 degreesC showed no excess Si and little residual carbon, and a chemical composition of 98.08 wt.% SiC and 1.92 wt.% SiO2 by SEM-EDX analysis.