• Title/Summary/Keyword: carbon materials

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Synthesis of Carbon Nanotubes by Chemical Method at Warm Temperatures (탄소나노튜브의 중저온에서의 화학적 합성)

  • Ahn, Jung-Ho;Lee, Sang-Hyun;Kim, Yong-Jin;Chung, Byung-Sik
    • Journal of Powder Materials
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    • v.13 no.5 s.58
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    • pp.305-312
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    • 2006
  • Amorphous carbon nanotubes were synthesized by a reaction of benzene, ferrocene and Na mixture in a small autoclave at temperatures as low as $400^{\circ}C$. The resulting carbon nanotubes were short and straight, but their inner hole was filled with residual products. The addition of quartz to the reacting mixture considerably promoted the formation of carbon nanotubes. A careful examination of powder structure suggested that the nanotubes in this process were mainly formed by surface diffusion of carbon atoms at the surface of solid catalytic particles, not by VLS(vapor-liquid-solid) mechanism.

In-situ rf treatment of multiwall carbon nanotube with various post techniques for enhanced field emission

  • Ahn, Kyoung-Soo;Kim, Jun-Sik;Kim, Ji-Hoon;Kim, Chae-Ok;Hong, Jin-Pyo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.859-862
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    • 2003
  • Well-aligned multiwall carbon nanotubes (MWCNTs) were prepared at low temperature of 400 $^{\circ}C$ by utilizing a radio frequency plasma-enhanced chemical vapor deposition (rf-PECVD) system. The MWCNTs were treated by an external rf plasma source and an ultra-violet laser in order to modify structural defect of carbon nanotube and to ablate possible contamination on carbon nanotube surface. Structural properties of carbon nanotubes were investigated by using a scanning electron microscopy (SEM), Raman spectroscopy, Fourier transformer Infrared spectroscopy (FTIR) and transmission electron microscope (TEM). In addition, the emission properties of the MWNTs were measured for the application of field emission display (FED) in near future. Various post treatments were found to improve the field emission property of carbon nanotubes.

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Effect of Coiling Temperature on the Annealed Texture in Cu/Nb Added Ultra Low Carbon Steels

  • Jiang, Yinghua;Park, Young-Koo;Lee, Oh-Yeon
    • Korean Journal of Materials Research
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    • v.18 no.2
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    • pp.65-68
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    • 2008
  • The present work was performed to investigate the effect of coiling temperature on the annealed texture in Cu/Nb-added ultra-low-carbon steels. The ultra-low-carbon steels were coiled at 650 and $720^{\circ}C$, respectively. The result showed that the Cu-added ultra-low-carbon steel at a low coiling temperature produced a desirable annealed texture related to good formability. On the other hand, Nb-added ultra-low-carbon steel at a high coiling temperature also produced a desirable texture. This is attributed to the effect of Nb, which retards recrystallization during the coiling process.

X-ray diffraction analysis of the effect of ball milling time on crystallinity of milled polyacrylonitrile-based carbon fiber

  • Lee, Sang-Hye;Kang, Dong-Su;Lee, Sang-Min;Roh, Jae-Seung
    • Carbon letters
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    • v.26
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    • pp.11-17
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    • 2018
  • Milled carbon fiber (mCF) was prepared by a ball milling process, and X-ray diffraction (XRD) diffractograms were obtained by a $2{\theta}$ continuous scanning analysis to study mCF crystallinity as a function of milling time. The raw material for the mCF was polyacrylonitrile-based carbon fiber (T700). As the milling time increased, the mean particle size of the mCF consistently decreased, reaching $1.826{\mu}m$ at a milling time of 18 h. The XRD analysis showed that, as the milling time increased, the fraction of the crystalline carbon decreased, while the fraction of the amorphous carbon increased. The (002) peak became asymmetric before and after milling as the left side of the peak showed an increasingly gentle slope. For analysis, the asymmetric (002) peak was deconvoluted into two peaks, less-developed crystalline carbon (LDCC) and more-developed crystalline carbon. In both peaks, Lc decreased and $d_{002}$ increased, but no significant change was observed after 6 h of milling time. In addition, the fraction of LDCC increased. As the milling continued, the mCF became more amorphous, possibly due to damage to the crystal lattices by the milling.

Applications of carbon-based materials in solid phase micro-extraction: a review

  • Guo, Jian;Park, Soo-Jin;Meng, Long-Yue;Jin, Xinghua
    • Carbon letters
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    • v.24
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    • pp.10-17
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    • 2017
  • With continuous development in the field of sample preparation technology, solid phase micro-extraction (SPME) has been widely used in analytical chemistry for high extraction efficiency and convenient operation. Different materials lead to different extraction results. Among existing materials, carbon-based materials are still attracting attention from scientists due to their excellent physical and chemical properties as well as their modifiable surfaces, which could enhance the adsorption effects of SPME fiber. This review introduces the preparation methods and applications of different kinds of carbon-based material coatings on fibers. In addition, directions for future research on carbon material composites are discussed.