Selective Mass Production of Carbon Nanotubes by Using Multi

Selective mass production of carbon nanotubes by using multi-layered and multi-electrodes AC arc plasma reactor 1. Introduction A number of processing of thermal plasmas has been applied for welding and cutting of metals. Thermal plasmas as high-temperature source with high energy -efficiency has been also tried to open new technological fields for better glo bal environment with related new industrial markets, including hazardous and waste treatments as well as material processing. In general, the power source for arc generation is accomplished by a direct current (DC) power supply. For inverting from AC to DC, higher cost is exp ected for larger capacity power s ource. Besides, a single-phase and a three-phase AC power supply as the alternative power sources have been proposed for arc zeneration [1, 2]. Arc generation systems by an AC power supply with high power have not b een ful ly developed, since these systems have inherent characteristics of intermittent discharge. In order to improve this defect, a multiple-phase AC power supply has been developed. To obtain a more effective arc generation by expanding this concept, w e have dev eloped a twelve-phase AC power supply [3]. The most important advantage of this system is that there are large number of discharging paths among the electrodes in comparison with the case of the single-phase and the three-phase systems. Therefore, some of the plasma paths always exist among the electrodes for the continuing smooth discharge. In order to improve this defect, a multiple-phase AC power supply has been developed. To obtain a more effective arc generation by expanding this conc ept, we have developed a t welve-phase AC power supply [3]. The most important advantage of this system is that there are large number of discharging paths among th e electrodes in comparison with the case of the single -phase and the three-phase systems. Therefore, some of the plasma paths always exist among the electrodes for the continuing smooth discharge. Carbon nanotubes (CNT) have been expected to realize the proper industrial usages for its unique ph ysical and chemical properties since they were d iscovered at first tim e in 1991. However, the progresses of the applications are not accelerated due to lack of high yield, high purity and cost reduction. Furthermore, no certain techniques are shown in selection of diameter, length, and the numbers of layers and the chilarity of the CNTs. On the other hand, the synthesis of CNTs such as DC arc discharge, laser ablation a nd thermal chemical vapor depo sition (CVD) are not perfectly satisfying methods in the field of ind ustrial applications. The DC arc discharge method can synthesize in highest quality than the ot her methods. But its yields are very few. Thought the CVD method is the mainstream of mass pro duction, its quality is not fully satisfied. In order to avoid the disadvanta ge of the DC arc discharge method keeping with its high quality, the twelv e ²ph ase AC arc discharge meth od was proposed in the previous paper s [4]. Single -walled carbon nano tubes (SWCNT), double-wal led carbon nanotube s (DWCNT) and multi-walled carbon nanotubes (MWCNT) ar e selectively synthesi zed at the different position in the same arc p lasma reactor by using multi layer twelve-phase AC arc discharge which can realize a large vo lume of three dimensional thermal plasma areas. Th e specifications of synthesized point, the combination of catalysis and gas pressure are investigated. Results and discussion

Selective Mass Production of Carbon Nanotubes by Using Multi

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