Master of Science in Mechanical Engineering (MSME)
Ever since their discovery carbon nanostructures (nanotubes and nanofibers) have attracted a lot of interest, due to their striking physical, chemical, mechanical and electrical properties, and paves the path to a wide range of applications. Large quantities of these structures are necessary to make their applications viable. The challenge is to produce them in bulk and in an economical way. Current methods like Arc discharge have the disadvantages of short tube lengths, CVD generated nanomaterials are often riddled with defects and although laser ablation method produces pure and high yield of nanotubes, is a costly technique with expensive lasers and high power equipment. Flame synthesis is one such technique, which meets the standards of commercial scalability. Also flame-generated particles are known for their low density and high surface areas, which are likely to enhance the adsorption properties of the materials. In this study flame synthesis is selected as a tool, to study in detail the growth mechanisms of these structures with different catalyst materials, and to establish the conditions (fuel equivalence ratio, residence time, type of metal catalyst) for maximum yield of these nanostructures. Three catalysts, Stainless steel (Fe/Cr/Ni), Nickel (99.8% pure) and Monel (Ni/Cu/Fe) wires were used to grow the carbon nanotubes and nanofibers. All these carbon nanostructures were characterized using scanning and transmission electron microscopy. The shape and size of carbon nanotubes and nanofibers produced was found to vary with the composition of catalyst material. TEM and SEM analysis shows that these carbon nanostructures are multiwalled nanotubes (MWNT’s) with diameter 27~40nm and nanofibers with diameter 0.125 to 0.5 microns. It was found that vertically aligned nanostructures can be produced using premixed flames.
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Perla, Saritha, "Flame synthesis of carbon-nanostructures" (2005). LSU Master's Theses. 1450.
Tryfon T. Charalampopoulos