• Title, Summary, Keyword: Carbon

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Distribution of Deposited Carbon in Carbon Brake Disc Made by Pressure-Gradient Chemical Vapor Infiltration

  • Chen, Jianxun;Xiong, Xiang
    • Carbon letters
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    • v.8 no.1
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    • pp.25-29
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    • 2007
  • The carbon brake discs were manufactured by densification the carbon fiber preform using PG-CVI technology with Propene as a carbon precursor gas and Nitrogen as a carrier gas. The densities of carbon brake discs were tested at different densification time. The results indicate that the densification rate is more rapid before 100 hrs than after 200 hrs. The CTscanning image and the SEM technology were used to observe the inner subtle structure. CT-images show the density distribution in the carbon brake disc clearly. The carbon brake disk made by PG-CVI is not very uniform. There is a density gradient in the bulk. The high-density part in the carbon brake is really located in the friction surface, especially in the part of inner circle. This density distribution is most suitable for the stator disc.

Properties of Carbon Black/SBR Rubber Composites Filled by Surface Modified Carbon Blacks

  • Dai, Shuang-Ye;Ao, Ge-You;Kim, Myung-Soo
    • Carbon letters
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    • v.8 no.2
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    • pp.115-119
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    • 2007
  • Properties of carbon blacks and carbon black/SBR rubber composites filled by surface modified carbon blacks were examined. Although the specific surface area of carbon blacks increased after the surface modifications with heat, acid, and base, there were no obvious changes in resistivity. The composites filled by heat treated carbon blacks showed a higher tensile strength and elongation than those filled by raw blacks. The acid and base treated carbon blacks filled composites also showed higher tensile strength but similar elongation values with those filled by raw blacks. With increasing loading ratio, both tensile strength and elongation increased, and appeared a maximum value at 30-40 phr. Modulus at 300% strain remained increasing with further loading of carbon blacks. At the same loading, the heat treated black filled composites showed similar modulus values with composites filled by raw blacks but for base and acid treated black filled composites much higher values were obtained. After the surface modification, the functional groups which played an important role in reinforcement action were changed.

Electrical Properties of Renewable Energy Carbon Film for Light Source Technology (광원 적용을 위한 신재생에너지 카본 박막의 전기적 특성)

  • Lee Sang-Heon
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.12
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    • pp.558-560
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    • 2005
  • The carbon film was deposited by the electrolysis of methanol solution. Carbon films have been grown on silicon substrates using the method of chemical process. From investigations of the Raman spectroscopy and the FTIR spectroscopy, the carbon film deposited by the electrolysis was identified the hydrogenated carbon film with the porous structure. The carbon film deposited by elctrolysis of methanol was identified as the hydrogenated carbon film with porous structure. Deposition parameters for the growth of the carbon films were current density, methanol liquid temperature. We electrical resistance and surface morphology of carbon films formed various conditions specified by deposition parameters. It was clarified that the high electrical resistance carbon films with smooth surface morphology are grown when a distance between the electrodes is relatively wider. We found that the electrical resistance in the films independent of both current density and methanol liquid temperature. The temperature dependence of the electrical resistance in the low resistance carbon films is different from one obtained in graphite..

Flexural Behaviors of 4D Carbon/carbon Composites with the Preform Architectures

  • Lee, Ki-Woong;Park, Jong-Min;Joo, Hyeok-Jong
    • Carbon letters
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    • v.9 no.1
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    • pp.28-34
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    • 2008
  • Multidirectional reinforcement is aimed primarily at overcoming interlaminar weakness, hence a major interest lies in the mechanical properties of multidirectional carbon/carbon composites. Mechanical properties depend on the type of carbon fiber, the size of the fiber bundle, the spacing of the bundles, the angles of the bundles relative to the axes of the block, and matrix formation. In the present studies, PAN based carbon fiber preforms manufactured different size of unit cell have been prepared. Densification of these used high pressure infiltration and carbonization technique with coal tar pitch as matrix precursor was carried out. Scanning electron microscopy has been used to study the fracture behavior of composites. The size of unit cell of the preforms has considerably affected on the flexural properties as well as microstructure of the carbon/carbon composites.

Ablative Properties of 4D Carbon/Carbon Composites by Combustion Test

  • Park, Jong-Min;Ahn, Chong-Jin;Joo, Hyeok-Jong
    • Carbon letters
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    • v.9 no.4
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    • pp.316-323
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    • 2008
  • The factors that influence ablation resistance in fiber composites are properties of the reinforced fiber and matrix, plugging quantity of fiber, geometrical arrangement, crack, pore size, and their distributions. To examine ablation resistance according to distribution of crack and pore size that exist in carbon/carbon composites, this study produced various sizes of unit cells of preforms. They were densified using high pressure impregnation and carbonization process. Reinforced fiber is PAN based carbon fiber and composites were heat-treated up to $2800^{\circ}C$. The finally acquired density of carbon/carbon composites reached more than $1.932\;g/cm^3$. The ablation test was performed by a solid propellant rocket engine. The erosion rate of samples is below 0.0286 mm/s. In conclusion, in terms of ablation properties, the higher degree of graphitization is, the more fibers that are arranged vertically to the direction of combustion flame are, and the less interface between reinforced fiber bundle and matrix is, the better ablation resistance is shown.

A Kinetic Study on the Phosphorus Adsorption by Physical Properties of Activated Carbon (활성탄 물성에 따른 인 흡착의 동력학적 연구)

  • Seo, Jeongbeom;Kang, Joonwon
    • Journal of Korean Society on Water Environment
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    • v.26 no.3
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    • pp.491-496
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    • 2010
  • This study aimed to obtain equilibrium concentration on adsorption removal of phosphorus by activated carbon, to express the adsorption characteristics following Freundlich isotherm and also, based on the value obtained, to investigate the relationship between physical properties of activated carbon and dynamics of phosphorus removal by obtaining rate constant and effective pore diffusivity. The results summarized from this study are as follows. Phosphorus adsorption equilibrium reaching time of powdered activated carbon was reduced as the dosage of activated carbon increases, while granular activated carbon despite increased dosage did not have influence on adsorption equilibrium reaching times of phosphorus as well, taking more than 10 hours. It was also noted that powdered activated carbon showed better adsorption ability than granular activated carbon. The value of constant (f) of Freundlich isotherm of powered activated carbon on phosphorus was 4.26 which is bigger than those of granular activated carbon. The adsorption rate constant on phosphorus of powered activated carbon with low effective diameter and iodine number was highest as $8.888hr^{-1}$ and the effective pore diffusivity ($D_e$) was lowest as $2.45{\times}10^{-5}cm^2/hr$, and the value of phosphorus adsorption rate constant of granular activated carbon was $0.174{\sim}0.372hr^{-1}$, It was revealed that, with the same amount of dosage, the adsorptive power of activated carbon with lower effective diameter was better and its rate constant was also high.

Evaluation of Tensile Properties of Carbon Fiber Reinforced Composite Laminates with Non-Woven Carbon Mat (부직포를 삽입한 탄소섬유강화 복합적층판의 인장특성 평가)

  • 정성균
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.6 no.4
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    • pp.96-100
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    • 1997
  • Tensile properties of carbon fiber reinforce composite laminates with non-woven carbon mat are evaluated in this paper. Composite laminates are made by inserting non-wovon carbon mat between layers, The specimens were cut and polished according to ASTM standard . Longitudinal and Transverse Young's modulus are obtained by tensile test. Young's moduli without non-woven carbon mat are compared with those with non-woven carbon mat. Longitudinal and Transverse tensile strength are also investigated. Experimental results show that the transverse Young's modulus of composite materials with non-woven carbon mat is about 10% higher than that of composite materials without non-woven carbon mat. Longitudinal tensile strength of composite materials with non-woven carbon mat is about 24% higher than that of composite materials without non-woven carbon mat. Transverse tensile strength and torughness also increase by inserting non-woven carbon mat between layers.

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Performance of the Negative Carbon Electrode Prepared with Graphitic Carbon and Nongraphitic Carbon Material in Lithium Ion Secondary Battery (흑연계 및 비흑연계 탄소로 조합된 리튬이온 이차전지의 탄소부극 특성)

  • Kim, Hyun-Joong;Lee, Chul-Tae
    • Applied Chemistry for Engineering
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    • v.9 no.7
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    • pp.1065-1069
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    • 1998
  • This study was investigated to improve peformance of carbon negative electrode for lithium ion secondary battery. The carbon electrode was prepared by mixing with graphitic carbon material, natural graphite, and nongraphitic carbon material, petroleum cokes, which was heat-treated at $700^{\circ}C$ for l hour. Its electrochemical and charge-discharge characteristics were tested according to mixing ratio of different two types of carbon material. The carbon electrode prepared with various mixing ratio showed both charateristcs of two different types of carbon materials and the best characteristics as carbon electrode was demonstrated at mixing ratio of 1:1.

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Observations of Variations in Soil Organic Carbon and Carbon Dioxide in the Constructed Wetland at Goheung Bay (고흥만 인공습지의 토양유기탄소와 이산화탄소 변동 관측)

  • Kang, Dong-Hwan;Kim, Sung-Soo;Kwon, Byung-Hyuk;Kim, Il-Kyu
    • Journal of Fisheries and Marine Sciences Education
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    • v.20 no.1
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    • pp.58-67
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    • 2008
  • Seasonal variations in carbon dioxide in the air and soil organic carbon in the sediments were monitored at the constructed wetland formed by reclamation work at Goheung Bay. Sediment sampling in the constructed wetland and carbon dioxide measurement in the air were conducted on June 16 and August 23, 2007. Sediments in the constructed wetland were sampled at 11 different points (June 16) and 14 points (August 23), while carbon dioxide in the air was measured at 13 points (June 16) and 15 points (August 23). Water content and organic carbon in the sampled sediments were analyzed in the laboratory. Water content of the sediments was higher than that of general soil, and the variation between June and August was not evident. The amounts of organic carbons in the sediments sampled on August 23 were higher than those sampled on June 16. Also, there was more organic carbon in the sediments sampled at the field of reeds than in the pure wetland area. Daily maximum variation in carbon dioxide in the air was higher on June 16, but the amount of carbon dioxide in the air was greater on August 23. The results of the study suggest that organic carbon in the sediments and carbon dioxide in the air were greater in summer (August 23) than in spring season (June 16) in the constructed wetland at Goheung Bay.

An investigation of tribology properties carbon nanotubes reinforced epoxy composites (표면 개질된 탄소나노튜브를 사용한 에폭시 복합재료의 마모특성에 관한 연구)

  • Sulong A.B.;Goak J.C.;Park Joo-Hyuk
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.663-667
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    • 2005
  • Surface modified carbon nanotubes were applied into the epoxy composites to investigate its tribological property. Carbon nanotubes reinforced epoxy composites were fabricated by casting. Effects to the tribological property of loading concentrations and types of surface modification of carbon nanotubes were investigated under sliding condition using linear reciprocal sliding wear tester. The results show that the small amount of carbon nanotubes into the epoxy exhibited lower weight loss than the pure epoxy. It is concluded that the effect of an enormous aspect ratio of carbon nanotubes surface area which wider than conventional fillers that react as interface for stress transfer. As increased the contents of carbon nanotubes, the weight loss from the wear test was reduced. And the surface modified carbon nanotubes show better tribological property than as produced carbon nanotubes. It is due that a surface modification of carbon nanotubes increases the interfacial bonding between carbon nanotubes and epoxy matrix through chemical bonding. Changes in worn surface morphology are also observed by optical microscope and SEM for investigating wear behaviors. Carbon nanotubes in the epoxy matrix near the surface are exposed, because it becomes the lubricating working film on the worn surface. It reduces the friction and results in the lower surface roughness morphology in the epoxy matrix as increasing the contents of the carbon nanotubes.

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