Preparation and dielectric properties of polymer-derived SiCTi ceramics

SiCTi ceramics were prepared by a polymer-derived-ceramic route, with allylhydridopolycarbosilane (AHPCS) and bis(cyclopentadienyl) titanium dichloride (Cp2TiCl2) as starting materials. The cross-linking and ceramization of the AHPCS/Cp2TiCl2 hybrid precursors were characterized by means of FT IR, NMR, TGA and EDS. The results indicate that the cross-linking of hybrid precursors was significantly catalyzed by using Cp2TiCl2 as a catalyst, which might be responsible for a high ceramic yield of 80.8% at 1200 °C. The polymer-to-ceramic conversion was completed at 900 °C to give an amorphous ceramic. The chemical composition of the final ceramics could be tailored by the weight ratio of Cp2TiCl2 to AHPCS in feed. The microstructure and dielectric properties of final SiCTi ceramics were investigated by means of XRD, Raman spectroscopy and vector network analyzer. The results indicate that the 1600 °C SiCTi ceramics are composed of amorphous SiCTi, SiC crystal, TiC crystal and graphite. The dielectric loss of SiCTi is up to 0.34, which is 6 times higher than that of SiC (0.058), indicating that the SiCTi ceramics are promising wave-absorbing materials.