Preparation and Properties of PCS/VHPCS Complex Silicon Carbide Precursors

Solid polycarbosilane and perhydropolycarbosilane are the most widely used polymer precursors for the preparation of silicon carbide ceramics and their composites. Complex silicon carbide ceramic precursors with different ratios of solid polycarbosilane (PCS) and vinyl perhydropolycarbosilane (VHPCS) were prepared, while physicochemical properties and structures of the precursors and their pyrolysis products were systematically studied. When the PCS mass fraction is lower than 30 wt.%, the viscosity of the PCS/VHPCS composite precursor is lower than 200 mPa·s. When the PCS mass fraction is lower than 20 wt.%, the ceramic yield can reach more than 80%. The PCS/VHPCS complex precursor derived ceramics are semi-crystalline β-SiC with small grain size, while no obvious grain boundaries were observed. The element distribution is uniform and the carbon-to-silicon ratio is lower than that of PCS-derived ceramics.