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

Abstract

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 TiCl 4 or Ti(NEt 2 ) 4 with bis(trimethylsilyl)carbodiimide. Subsequent pyrolysis at 1000°C in argon results in the formation of a ceramic composite material consisting of nanocrystalline TiCN and amorphous SiCN as constituting phases. Using Ti(NEt 2 ) 4 as a starting reagent instead of TiCl 4 , chlorine contamination of the ceramic material can be avoided. The different molecular vibration modes of the metal-nitrogen, metal-carbon and nitrogencarbon bonds in poly(titaniumcarbodiimides) with trimethylsilyl substituents were calculated using quantum mechanical methods, providing a comprehensive understanding of the measured spectra.

Formation of nanocrystalline titanium carbonitride by pyrolysis of poly(titanylcarbodiimide)

“…The relative small amount of carbon in this material (Fig. 1) indicates the high loss of carbon containing molecular fragments during pyrolysis (mainly HCN, CH 4 , CH 3 CN, and (CH 3 ) 3 SiOSi(CH 3 ) 3 ), which we reported previously [7], investigated by thermal gravimetric analysis and simultaneous mass spectrometry.…”

“…In a foregoing paper [7] we presented general reaction conditions for the synthesis and the characterisation of the Ti-C-N-precursor by infrared absorption and Raman spectroscopy, and of the ceramic material by X-ray powder diffraction. In this paper, we report on the synthesis of nanocrystalline titanium carbonitride materials at different pyrolysis temperatures via the polymer-to-ceramic transformation [8][9][10] of a newly developed titaniumcarbodiimide polymer [7] and their structural and nanochemical characterisation using high-resolution and analytical electron microscopy in combination with quantummechanical calculations.…”

“…In this paper, we report on the synthesis of nanocrystalline titanium carbonitride materials at different pyrolysis temperatures via the polymer-to-ceramic transformation [8][9][10] of a newly developed titaniumcarbodiimide polymer [7] and their structural and nanochemical characterisation using high-resolution and analytical electron microscopy in combination with quantummechanical calculations.…”

A new route for preparation of sodium-silicate-based hydrophobic silica aerogels via ambient-pressure drying

“…The surface modification of the aerogel for different silylation periods from 6 to 24 h is confirmed by the FTIR spectra of the aerogels as shown in figure 15. It was observed that with increasing silylation period, the intensity of -OH bond peaks at 1600 and 3400 cm −1 [35] decreased, and the peaks related to C-H at 2960 and 1450 cm −1 and those related to Si-C at 840 and 1260 cm −1 increased [36]. Thus, the dependence of surface modification on the silylation period was clearly observed.…”

Synthesis of SiOC(–H) Films by the Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition Method

“…Peaks attributed to Si-O-Si symmetric stretching vibrations and bending mode was observed around 1100 cm −1 and 800 cm −1 , respectively [27,28]. In the case of SiOC(-H) films, the intense band between 1020 cm −1 and 1250 cm −1 is related to Si-O-Si and Si-O-C asymmetric stretch modes [29].…”