| The work of this thesis is the experimental investigation of various types of carbon nanostructures formed in the oxy-fuel flame media. Soot volume fraction (particle density), soot morphology (primary particle diameter, degree of agglomeration, and the internal and external particle structure), CNTs (synthesis optimization and morphology), and fullerenes are being investigated in this work. These materials are characterized by means of light scattering and optical analysis, transmission electron microscopy (TEM), and scanning electron microscopy (SEM).; Soot particles were investigated using the laser extinction method and by thermophoretic sampling technique. It was found that as the oxygen content increased, the soot volume fraction also tended to increase. High-resolution TEM imaging on the trapped material reveals the presence of highly crystalline soot structures.; A catalytic support was positioned at the fuel side of the counter-flow flame formed by fuel (96%CH4+4%C2H2) and oxidizer (50%O2+50%N2) streams. TEM and SEM studies reveal the presence of a variety of highly organized carbonaceous structures with the configurations showing strong dependence on the flame location. It is observed that when a catalytic probe is inserted in the flame under an electric field control, a coating layer of vertically aligned carbon nanotubes covering the catalytic surface of the probe is formed. These results show that electric fields can be applied as a means to control CNT structure and growth rates. Overall, the electric field control method demonstrates stabilization of the structure in a wide flame region while growth rate remains dependent on flame location.; The presence of fullerenes produced in the flame was detected using high resolution TEM and high pressure liquid chromatography. We found that large amounts of fullerenes (C60+ C70) can be generated using the counter-flow flame at normal atmospheric conditions. |
