Flame synthesis of carbon nanotubes
Flame synthesis of carbon nanostructures including nanotubes on galvanized steel was investigated utilizing laminar diffusion flames. Methane (CH 4), propane (C3H8) and acetylene (C2H 2) were used as the carbon source. Distinctive carbon nanostructures were produced depending on the fuel type and fuel flow rate. The quantitative analysis of many transmission electron microscope (TEM) and scanning electron microscope (SEM) images was performed. The nanotubes synthesized by acetylene flames were of different types that included helically coiled nanotubes depending on the fuel flow rate. Methane produced thin multi wall carbon nanotubes as well as nanorods and nanofibers within the fuel flow rate range of 7.18E-07 m3/s to 9.57E-07 m3/s. Propane yielded nanotubes only at the fuel flow rate of 4.20E-07 m3/s. ^ A flame synthesis technique of coiled carbon nanotubes using acetylene jet flames and galvanized steel catalyst is presented. It was found that acetylene flames generate coiled nanotubes within a narrow pyrolysis zone above the burner for a limited range of fuel flow rates. The corresponding local convective time scale corresponding to the coiled nanotube formation zone is around 0.04 ms. The yield of the coiled carbon nanotubes was further increased by changing the local convective time scale with the addition of controlled turbulence. Turbulent flames synthesized about 60% more carbon material than the laminar flames under the same conditions. In average, carbon nanotubes oxidized at a temperature of about 618°C with a residual mass of about 14% of the material weight. ^
Engineering, Mechanical|Engineering, Materials Science
Camacho Rosiles, Jorge, "Flame synthesis of carbon nanotubes" (2005). ETD Collection for University of Texas, El Paso. AAI3209842.