Synthesis and Characterization of SiC(Ti) Ceramics Derived from a Hybrid Precursor of Titanium-Containing Polycarbosilane

A hybrid precursor of titanium-containing polycarbosilane is prepared by blending hyperbranched polycarbosilane (HBPCS) and tetrabutyl titanate (TBT), and then crosslinking at 160 °C, followed by pyrolyzing at high temperatures to afford SiC(Ti) ceramics. The crosslinking reaction of HBPCS–TBT hybrid precursor is investigated by FT-IR, solid state 29Si MAS NMR, and GPC. The results indicate that the crosslinking reaction takes place via condensation between the Si–H bond of HBPCS and butoxy group in TBT leading to the formation of Si–O–Ti bonds. The thermal properties and structural evolution of crosslinked hybrid precursor and the crystallization behavior and composition of final ceramics are investigated by TGA, FT-IR, Raman spectroscopy, XRD and energy dispersive elemental analysis. The ceramic yield of hybrid precursor is significantly enhanced by introduction of TBT. The ceramic yield at 1,400 °C is 83% for HBPCS–TBT-5 as measured by TGA. The Ti-content in the ceramic is controlled by varying the TBT content in the feed. The SiC(Ti) ceramic is amorphous at 900 °C. The characteristic peaks of β-SiC and TiC appear until 1,600 °C. The growth of SiC crystals is inhibited by the formation of TiC.