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 descr ibed. The precursor and the subsequent processing steps (cross-linking and pyrolysis) are characterized by IR and Raman spectroscopy, thermal gravimet ric analysis and simultaneous mass spectroscopy, electron microscopy and po wder X-ray diffraction measurements. The novel polymer is formed by the rea ction of TiCl4 or Ti(NEt2)(4) with bis(trimethylsilyl)carbodiimide. Subsequ ent pyrolysis at 1000 degreesC in argon results in the formation of a ceram ic 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 s ubstituents were calculated using quantum mechanical methods, providing a c omprehensive understanding of the measured spectra. Copyright (C) 2001 John Wiley & Sons, Ltd.