A microstructural study of silicon carbide fibres through the use of Raman microscopy

The microstructures of three different silicon carbide (SiC) fibres produced by CVD (chemical vapour deposition) have been examined in detail using Raman microscopy. Raman spectra were mapped out across the entire cross-sections of these silicon carbide fibres using an automated x-y stage with a spatial 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+ fibre also contains free silicon. Furthermore, the differences in the detailed structures of the carbon and silicon carbide present in the fibres can also be investigated. Raman microscopy is demonstrated to be a very sensitive technique for characterising the composition and microstructure of CVD silicon carbide fibres prepared using different processing conditions. (C) 2001 Kluwer Academic Publishers.