• Carbon letters
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• v.11 no.3
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• pp.184-191
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• 2010

Carbon nanotubes are unique tubular structures of nanometer diameter and large length/diameter ratio. The nanotubes may consist of one up to tens and hundreds of concentric shells of carbons with adjacent shells separation of ~0.34 nm. Multiwalled carbon nanotubes were synthesized by arc-discharge technique. MWCNTs were formed at the cathode deposit along with other carbonaceous materials like amorphous carbon, graphite etc. However, to get the best advantage of carbon nanotubes in various advanced applications, these undesired carbonaceous materials to be removed which is a challenging task. In the present study, various techniques were tried out for purifying MWCNTs such as physical filtration, chemical treatment and thermal annealing. SEM, FTIR, TGA and BET techniques were used to characterize the CNTs at various stages. Results shows that suitable chemical treatment followed by thermal annealing under controlled flow of oxygen gives the better route for purification of carbon nanotubes.

• 한국전기화학회:학술대회논문집
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• 2003.10a
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• pp.45-45
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• 2003

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.7-14
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• 2008

Carbon nanotubes are considered as the most ideal nano filler in the field of composites with their excellent electrical, mechanical, and thermal properties. Therefore carbon nanotubes composites are increasingly utilized in conductive materials, structural material with high strength and low weight and multifunctional material. This review article describes recent research trend of carbon nanotubes synthesis, modification, various properties of the carbon nanotubes composites and their application. Furthermore the future development direction for the commercialization of carbon nanotubes composites is proposed.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.212-212
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• 2000

Since the first obserbvation of carbon nanotubes, extensive researches have been done for the synthesis using arc discharge, laser vaporization, and plasma-enhanced chemical vapor deposition. Carbon nanotubes have unique physical and chemical properties and can allow nanoscale devices. Vertically aligned carbon nanotubes with high quality on a large area is particularly important to enable both fundamental studies and applications, such as flat panel displays and vacuum microelectronics. we have grown vertically aligned carbon nanotubes on a large area of Si substrates by thermal chemical vapor deposition using C2H2 gas at 750-950$^{\circ}C$. we deposited catalytic metal on Si susbstrate using thermal evaporation. The nanotubes reveal highly purified surface. The carbon nanotubes have multi-wall structure with a hollow inside and it reveals bamboo structure agreed with base growth model. Figure 1 shows SEM micrograph showing vertically aligned carbon nanotubes whih were grown at 950$^{\circ}C$ on a large area (20mm${\times}$30mm) of Si substrates. Figure 2 shows TEM analysis was performed on the carbon nanotubes grown at 950$^{\circ}C$ for 10 min. The carbon nanotubes are multi-wall structure with bamboo shape and the lack of fringes inside the nanotube indicates that the core of the structure is hollow. In our experiment, carbon nanotubes grown by the thermal CVD indicate base growth model.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.659-662
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• 2003

• Carbon letters
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• v.10 no.2
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• pp.87-89
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• 2009

Carbon nanotubes, consisting of rolled graphene layer built from $sp^2$ units, have attracted the imagination of scientists as ideal macromolecules and their unusual physical and chemical properties make them useful in the fabrication of nanocomposites, nano-electronic devices and sensors etc. In this account, the current status and prospect of carbon nanotubes is described with a special emphasis on the safety issue of carbon nanotubes. Even though many challenges to be solved remain, extensive and intensive efforts in both academy and industry will clear out those problems soon and finally enable carbon nanotubes to play a key innovative material of 21st century in numerous industrial processes.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.171-178
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• 2006

The sonication mettled is widely used with surfactants to suspend individual single-walled carbon nanotubes in solution, and it is well known that sonication-induced tube cutting occurs. Recently, it is found out that ultrasonicated nanotubes yield simultaneous separation by tube length and diameter. Nanotubes that have been cut shortest possess the greatest enrichments of large-diameter species. In this study, single-walled carbon nanotubes are cut using a ball milling method. Similar fracture behavior is observed fur the ball milled nanotubes: i.e., large diameter tubes are cut shorter. The ability to separate carbon nanotubes by diameter and length will contribute to tile development of nanotube-based applications.

• Journal of Power System Engineering
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• v.21 no.4
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• pp.94-99
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• 2017

Single walled carbon nanotubes were mixed with various metal powders by mechanical ball milling and sintered by spark plasma sintering processes. Two compositional (0.1 and 1 vol%) of the single walled carbon nanotubes were dispersed onto the pure aluminum, 5052 aluminum alloy, pure titanium, Ti6Al4Vanadium alloy, pure copper, and stainless steel 316L. Each composite powders were spark plasma sintered at $600^{\circ}C$ and well synthesized regardless of the matrices. Vickers hardness of the composite materials was measured and they exhibited higher values regardless of the carbon nanotubes composition than those of the pure materials. Moreover, single walled carbon nanotubes reinforced copper matrix composites showed highest enhancement between the other metal matrices system. We believe that low energy mechanical ball milling and spark plasma sintering processes are useful tool for fabricating of the carbon nanotubes-reinforced various metal matrices composite materials. The single walled carbon nanotubes-reinforced various metal matrices composite materials could be used as an engineering parts in many kind of industrial fields such as aviation, transportation and electro technologies etc. However, detail strengthening mechanism should be carefully investigated.

• Journal of Powder Materials
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• v.24 no.3
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• pp.248-253
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• 2017

In this study, we investigate the effect of the diffusion barrier and substrate temperature on the length of carbon nanotubes. For synthesizing vertically aligned carbon nanotubes, thermal chemical vapor deposition is used and a substrate with a catalytic layer and a buffer layer is prepared using an e-beam evaporator. The length of the carbon nanotubes synthesized on the catalytic layer/diffusion barrier on the silicon substrate is longer than that without a diffusion barrier because the diffusion barrier prevents generation of silicon carbide from the diffusion of carbon atoms into the silicon substrate. The deposition temperature of the catalyst and alumina are varied from room temperature to $150^{\circ}C$, $200^{\circ}C$, and $250^{\circ}C$. On increasing the substrate temperature on depositing the buffer layer on the silicon substrate, shorter carbon nanotubes are obtained owing to the increased bonding force between the buffer layer and silicon substrate. The reason why different lengths of carbon nanotubes are obtained is that the higher bonding force between the buffer layer and the substrate layer prevents uniformity of catalytic islands for synthesizing carbon nanotubes.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.697-700
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• 2002

Porous anodic aluminum oxide(AAO) templates prepared by anodizing method were used for growing multiwalled carbon nanotubes(CNTs). AAO templates with the homogeneous pore diameter and length were obtained by two step anodizing technique. Using AAO templates, vertically well-ordered two-dimensional carbon nanotube arrays were fabricated. We investigated the field emission property of CNTs grown using different catalyst metals in vacuum chamber (<$10^{-7}$ Torr) on AAO Template. To explain the different emission property, the surface reaction between catalysts and alumina pores which inserted carbon species of $C_2H_2$ using High resolution transmission electron microscopy (HRTEM) was studied.