Investigation of microstructure of CVD carbon coating on SiC fiber by Raman spectrometer

: The microstructure and fracture morphology of carbon coatings were investigated by means of Raman spectrometer and scanning electron microscopy (SEM), which were prepared by chemical vapor deposition (CVD) on the surface of SiC fiber with C2 H2 + H2 and C2 H2 +C3 H8 + Ar as the reactants. The results show that the spectra of the carbon coating contain characteristic D, D" and G peaks around 1 350, 1 400-1 500 and 1 600 cm(-1) respectively, indicating a disordered-graphite structure with a small amount of amorphous carbon. The size of microcrystallite increased with the increase in temperature, and the degree of order, together with the uniformity in the carbon coating was improved simultaneously. It was observed on the fracture surface that coatings prepared by C2 H2 + H2 are flat and dense, whereas those prepared by C2 H2 + C3 H8 + Ar exhibit a flexural lamellar structure, which should be attributed to the relatively low degree of order and the non-uniformity in the microstructure.