A microstructural study of silicon carbide fibres through the use of Ramanmicroscopy

The microstructures of three different silicon carbide (SiC) fibres produce d by CVD (chemical vapour deposition) have been examined in detail using Ra man microscopy. Raman spectra were mapped out across the entire cross-secti ons of these silicon carbide fibres using an automated x-y stage with a spa tial resolution of 1 mum. The Raman maps clearly illustrate the variations in microstructure in such types of silicon carbide fibres. It appears that the SCS-type fibres contain carbon as well as SiC whereas the Sigma 1140+ f ibre also contains free silicon. Furthermore, the differences in the detail ed structures of the carbon and silicon carbide present in the fibres can a lso be investigated. Raman microscopy is demonstrated to be a very sensitiv e technique for characterising the composition and microstructure of CVD si licon carbide fibres prepared using different processing conditions. (C) 20 01 Kluwer Academic Publishers.