Sintering of silcon carbide prepared from a polymeric precursor

A polysilane precursor to SiC was doped with 0, 0.5, and 2 wt% B4C powder and heated to 1000, 1900, 2000, and 2100 degrees C. Chemical and structural characteristics of the intermediate and final products were investigated using chemical analysis, x-ray powder diffraction, and scanning electron microscopy. Residue densification promoted by boron carbide exceeded 90% of theoretical, similar to boron-enhanced sintering of silicon carbide powder. The polymer residue contained ∼ 19 wt% excess carbon which crystallized at the sintering temperatures. These results are applicable to polysilane polymers both as binders for silicon carbide powders and as precursors to thermally stable fibers