Comparison of the SiH4---C2H4 and SiH2Cl2---C2H4 systems during the synthesis of silicon carbide ultrafine particles by laser-induced gas-phase reaction

The synthesis conditions of SiC ultrafine particles from SiH₄ and C₂H₄ using a CO₂ laser were studied and a comparison was made between SiH₄---C₂H₄ and SiH₂Cl₂---C₂H₄ systems. Ultrafine SiC particles were synthesized by irradiating a SiH₄ and C₂H₄ gas mixture with a CO₂ laser at atmospheric pressure. SiC particles were obtained at a laser power of more than 0·92 kW/cm².

The behavior of the reaction flame temperature and the extent of the laser light absorption by SiH₄---C₂H₄ was different from that of SiH₂Cl₂---C₂H₄, although an abrupt temperature increase was observed in both cases. In the case of SiH₄---C₂H₄ an abrupt increase in the laser light absorption was not observed, whilst it was observed in the case of SiH₂Cl₂---C₂H₄. This difference resulted from the difference in liability to form solid carbon particles.