Carbon black (CB) nanopowders were obtained by plasma decomposition of methane at various flow rates using inductively coupled thermal plasma torch system of 35 kW. Nitrogen was also introduced in some experiments along with the methane. Using a cylindrical shape reactor the obtained powders were composed mainly of spherical particles, non-uniform in terms of particles size with diameters between 30 and 150 nm. The shape and size of this reactor resulted in the presence of recirculation areas enabling the formation of large CB particles and other secondary volatile compounds. Changing the reactor to a conical geometry resulted in the production of CB powders showing a crystalline and flake-like morphology made of sheets having 6-16 graphitic planes. The conical shape avoids the presence of recirculation areas and promotes the formation of a uniform powder morphology throughout the reactor.

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Carbon material was produced using an inductively coupled thermal plasma torch system of 35 kW and a conical shape reactor. The carbon nanopowders were obtained by plasma decomposition of methane at various flow rates and show a uniform microstructure throughout the reactor. The product has a crystalline graphitic structure, with a stacking of between 6 and 16 planes and a nano-flake morphology with particles dimensions of approximately 100 nm long, 50 nm wide and 5 nm thick. Nitrogen was also introduced in some synthesis experiments along with the methane precursor using flow rates of 0.1 and 0.2 slpm. The resulting product has the same structural properties and the nitrogen is incorporated into the graphitic structure through pyridinic type bonds.

The process control for reproducibility, uniformity, and achievement of desired structures for carbon black generated in thermal plasma devices is studied in this paper through modeling, and correlated with experimental results. A numerical simulation of the flow and energy fields, stream function lines and the quench rates of the plasma gas in a conical shape reactor at different pressures was made. An argon plasma is used with highly diluted methane (0.6-7%) as the carbon precursor. The quench rates were studied in order to observe the flow development and hence the thermal history of particle nucleation. Three pressure cases of 20.7, 55.2 and 101.3 kPa and two plasma powers cases of 10 and 20 kW were studied. The modeling results enabled carbon nanoflakes production in the experimental tests performed on an inductively coupled thermal plasma system. Results indicate a robust process control enabling very little particle morphology variation over this wide range of reactor pressure values and varying plasma power, and a very high reproducibility of the particle morphologies obtained.

Carbon black nanopowders were produced using two thermal plasma processes based on DC, respectively ICP plasma torches. Although the produced particles were in the nanometer size range, the values obtained for the surface area of the particles using a Brunauer Emmett Teller technique were very small. This indicated the presence of contaminants in the experimental powders, as confirmed by Raman spectroscopy and Thermogravimetric Analysis. A thermal treatment process was developed in order to extract these volatile compounds, which were then identified using a Gas Chromatography-Mass Spectrometry method. The experimental powders were analyzed using Scanning and Transmission Electron Microscopy, X-Ray Diffraction and Raman Spectroscopy before and after the thermal treatment in order to determine the effect of the heat treatment on the powder structural properties.