Methods for the Synthesis of Endohedral Fullerenes

In the present manuscript the authors show the progress recorded regarding the main synthesis methods of metal endo-fullerenes. Shown, that nowadays, the most productive and common method of producing endohedral fullerenes is the electric arc process due to the fact that (a) it is simple enough to introduce atoms into the plasma from solids and gases; (b) its performance is the highest among other methods; (c) gives a wide range of produced types of metallofullerenes in an inert atmosphere-mono-, di-, tri-metalfullerenes, metal carbide clusters, in a reactive atmosphere (N2, NH3)-metal nitride and cyanide clusters, heterofullerenes; (d) provides the greatest energy potential, which is likely to allow the introduction into the cells of fullerene molecules metal atoms with higher ionization energies than titanium (≥7 eV). The yield of metal endofullerenes is substantially higher than the “empty” fullerenes. In this case, the stabilization of both metal atoms and fullerene cells occurs. The quantitative and qualitative output of MEF is significantly affected by: (a) conditions of the process in the reactor: the gas pressure, its flow rate, temperature, amperage; the distance between the electrodes, and others, that is, those factors that determine the plasma temperature and the residence time of the reaction particles in it; (b) the composition of solid additives (salts, oxides, metal alloys) in the graphite anode and their quantitative (mol) ratio with carbon; (c) replacement of the inert atmosphere of the synthesis with the active one (helium-with nitrogen, ammonia, water vapor, CO and other gases).

Research on the Impact of Amplitude of Vibrations on Electrical Parameters of Vibroarc Weld Overlay in Argon

The research is taken on the vibroarc welding apparatus ENTON-60 equipped with an axial non-inertial vibrator in argon shield. The criteria used for assessing the flow of the electric arc process and the formation of weld overlay clad surfaces are: short circuit voltage, voltage at the start of arc combustion, short circuit amperage, and amperage at the end of arc combustion. Wire electrode‘s vibrating frequency is considered as an input variable of the cybernetic model. It has been found that amplitude of vibrations has a significant impact on the vibroarc process - voltage parameters and welding current ratio, as the minimum amperage of short circuit and the lowest voltage at the start of arc combustion is realized at 2 mm amplitude of vibrations.

Thermodynamic Equilibrium Calculation of Oxygen-Fuel Process of Calcium Carbide Production

The oxygen-fuel process of calcium carbide production refers to the application of oxygen-enriched combustion technology in production of calcium carbide and the method was introduced. The material and thermal equilibrium calculation of this method were done, and compared with electric arc process. The power consumption was greatly reduced and the production temperature of CaC2was reduced, the more economic income of the method can be gained through the comparison, at the same time which can provided theoretical support for the follow study of this method.

Radiative Heat Transfer During Growth of Carbon Nanotubes by Vertical Electric-Arc Process

A macroscopic finite elements model of heat transfer occurring during production of carbon nanotubes was developed. Radiation heat transfer was modeled using the Discrete Ordinates (DO) model and the Rosseland diffusion approximation. The arc is modeled as semitransparent, with the optical thickness ranging from zero to infinity. The results are compared to the limited data available. The optical thickens has a significant impact on the temperature field in (i) the arc and (ii) the anode surfaces exposed to the arc. The temperature of the cathode side-surface on which the small diameter carbon nanotube grew, is not sensitive to the optical thickness of the arc. The model indicates that the optical thickness of the arc should be high, aL ≥ 100.