Silicon carbonitride ceramics derived from polysilazanes Part I. Investigation of compositional and structural properties

In this paper we report on the compositional and structural properties of ceramics in the Si–C–N system. The amorphous material synthesised by thermally induced ceramisation of an organo-substituted polysilazane crystallises at temperatures exceeding 1450°C in nitrogen atmosphere. Chemical composition, solid state structure, microstructure as well as the crystallisation behaviour depend on: (i) the synthesis conditions; (ii) the pyrolysis atmosphere; and (iii) the time and temperature of a final heat treatment. The chemical composition was determined by chemical bulk analysis together with 15N-method and electron energy-loss spectroscopy (EELS). Reaction products formed during the heat treatment were analysed in-situ by thermal gravimetric analysis coupled with mass spectrometry. The hybridisation of carbon in the solid reaction product was determined by X-ray absorption near-edge structure (XANES). The resulting amorphous microstructure was investigated by electron microscopy (HRTEM), while the crystalline phases were analysed by X-ray diffraction (XRD).