Synthesis of polymeric precursors for the formation of nanocrystalline Ti-C-N/amorphous Si-C-N composites

The synthesis of trimethylsilyl-substituted poly(titaniumcarbodiimide) as a novel precursor for titanium carbonitride based ceramic materials is described. The precursor and the subsequent processing steps (cross-linking and pyrolysis) are characterized by IR and Raman spectroscopy, thermal gravimetric analysis and simultaneous mass spectroscopy, electron microscopy and powder X-ray diffraction measurements. The novel polymer is formed by the reaction of TiCl4 or Ti(NEt2)(4) with bis(trimethylsilyl)carbodiimide. Subsequent pyrolysis at 1000 degreesC in argon results in the formation of a ceramic composite material consisting of nanocrystalline TiCN and amorphous SiCN as constituting phases. Using Ti(NEt2)(4) as a starting reagent instead of TiCl4, chlorine contamination of the ceramic material can be avoided. The different molecular vibration modes of the metal-nitrogen, metal-carbon and nitrogen-carbon bonds in poly(titaniumcarbodiimides) with trimethylsilyl substituents were calculated using quantum mechanical methods, providing a comprehensive understanding of the measured spectra. Copyright (C) 2001 John Wiley & Sons, Ltd.