• Title, Summary, Keyword: Carbon

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The Effect of Pressure on the Properties of Carbon/Carbon Composites during the Carbonization Process

  • Joo, Hyeok-Jong;Oh, In-Hwan
    • Carbon letters
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    • v.3 no.2
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    • pp.85-92
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    • 2002
  • 4D carbon fiber preforms were manufactured by weaving method and their carbon fiber volume fractions were 50% and 60%. In order to form carbon matrix on the preform, coal tar pitch was used for matrix precursor and high density carbon/carbon composites were obtained by high densification process. In this process, manufacture of high density composites was more effective according to pressure increasement. When densificating the preform of 60% fiber volume fraction with 900 bar, density of the composites reached at 1.90 $g/cm^3$ after three times processing. Degree of pressure in the densification process controls macro pore but it can not affect micro pore. During the carbonization process, micro pore of the preform were filled fully by once or twice densification processing. But micro pore were not filled easily in the repeating process. Therefore, over three times densification processing is the filling micro pore.

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The Vibration Characteristic of Carbon-Carbon Composite Material due to Tensile Loading (인장하중에 따른 Carbon/Carbon복합재의 진동특성)

  • Oh, Seung-Gyu;Kwac, Lee-Ku;Kim, Hong-Gun
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.20 no.6
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    • pp.740-744
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    • 2011
  • Carbon-carbon composite material is the reinforced carbon fiber. Because of its high strength, elasticity and the excellent heat-resisting property in high temperature, carbon-carbon composite material has been used in many fields such as aerospace and automotive industries, etc. Especially, aircraft brake discs used at aerospace can be cracked due to its fatigue and vibration under various loading condition. This research is focused on the influence of the vibration of carbon-carbon composite material by using accelerometer with impact hammer excitation. And the change of vibration mode will be known by applying tensile loading test.

Effect of Carbonization Temperature on Carbon Dioxide Adsorption Behaviors of mesoporous carbon (중기공 탄소의 탄화온도에 따른 이산화탄소 흡착 거동)

  • Jang, Dong-Il;Park, Soo-Jin
    • 한국신재생에너지학회:학술대회논문집
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    • pp.221.1-221.1
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    • 2011
  • In this study, we prepared the nitrogen-containing carbon spheres with mesopore processed by a facile polymerization-induced colloid aggregation method including carbonization in order to investigate the characterization and the effect on their carbon dioxide adsorption behaviors. The carbonization temperature was varied in the range of $600^{\circ}C$ to $900^{\circ}C$. The nitrogen contents of the mesoporous carbon sphere were characterized using XPS. The carbon dioxide adsorption capacities of the prepared mesoporous carbon sphere were determined by the amounts of carbon dioxide adsorptions at 298 K and 1.0 atm. The results showed that the prepared mesoporous carbons were highly effective for the carbon dioxide adsorption due to the increasing the affinity of the basic functionalities of adsorbent surface to acidic carbon dioxide. Maximum adsorption capacities of carbon dioxide at $25^{\circ}C$ were achieved up to 106 mg/g.

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Formation of Isotropic Carbon Matrix in Carbon/Carbon Composites Derived from Pitch

  • Ahn, Chong-Jin;Park, In-Seo;Joo, Hyeok-Jong
    • Carbon letters
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    • v.11 no.4
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    • pp.304-310
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    • 2010
  • To manufacture a carbon/carbon composite the coal tar pitch was used as the matrix precursor and the PAN (polyacrylonitrile)-based carbon fiber was used as the reinforcing material to weave 3-directional preform. For pressure carbonization HIP equipment was used to produce a maximum temperature of $1000^{\circ}C$ and a maximum pressure of 100 MPa. The carbonization was induced by altering the dwell temperature between $250^{\circ}C$ and $420^{\circ}C$, which is an ideal temperature for the moderate growth of the mesophase nucleus that forms within the molten pitch during the pressure carbonization process. The application of high pressure during the carbonization process inhibits the mesophase growth and leads to the formation of spherical carbon particles that are approximately 30 nm in size. Most particles were spherical, but some particles were irregularly shaped. The spread of the carbon particles was larger on the surface of the carbon fiber than in the interior of the matrix pocket.

Effect of Surface Treatment of Carbon Fiber on the Impact Property of Carbon/carbon Composites (탄소섬유의 표면처리에 따른 탄소/탄소 복합재료의 충격 성질 변화)

  • 이준석;강태진
    • Textile Science and Engineering
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    • v.34 no.12
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    • pp.884-890
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    • 1997
  • The effects of surface treatment of high strength carbon fibers on the impact properties of 2D and 3D carbon fiber reinforced composites and carbon/carbon composites are studied. It is found that air oxidation of carbon fibers deteriorates the impact property of the composites because of declined fiber/matrix interfacial strength due to creation of micro-pore on the carbon fiber surface. The impact property of heat treated (HT700 and HT950) carbon composites is superior to that of any other treated composites because of increased effective surface area of carbon fibers. The 3D structure is suitable for carbon/carbon composite in toughening aspect.

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Densification of 4D Carbon Fiber Performs with Mesophase Pitch as Matrix-Precursor

  • Joo, Hyeok-Jong;Lee, Jae-Won
    • Carbon letters
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    • v.6 no.3
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    • pp.173-180
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    • 2005
  • In this study, AR (aromatic resin) pitch was employed as the matrix-precursor for carbon/carbon composite because it exhibits much higher coke yield than coal tar pitch. As a result, a fabrication process of carbon/carbon composites can be shortened. It has been known that the pitches may cause swolling problem during the carbonization process. In order to restrain the swelling occurrence, a small quantity of carbon black was added to the AR pitch. Due to addition of carbon black the swelling was decreased largely and the perform can be infiltrated with the AR pitch. The densification efficiency of the performs was compared with various matrix-precursors. The coke yield of matrixprecursors, the morphology and the degree of graphitization of carbon matrix were analyzed.

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Heat resistance of carbon nanoonions by molecular dynamics simulation

  • Wang, Xianqiao;Lee, James D.
    • Interaction and multiscale mechanics
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    • v.4 no.4
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    • pp.247-255
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    • 2011
  • Understanding the structural stability of carbon nanostructure under heat treatment is critical for tailoring the thermal properties of carbon-based material at small length scales. We investigate the heat resistance of the single carbon nanoball ($C_{60}$) and carbon nanoonions ($C_{20}@C_{80}$, $C_{20}@C_{80}@C_{180}$, $C_{20}@C_{80}@C_{180}C_{320}$) by performing molecular dynamics simulations. An empirical many-body potential function, Tersoff potential, for carbon is employed to calculate the interaction force among carbon atoms. Simulation results shows that carbon nanoonions are less resistive against heat treatment than single carbon nanoballs. Single carbon nanoballs such $C_{60}$ can resist heat treatment up to 5600 K, however, carbon nanoonions break down after 5100 K. This intriguing result offers insights into understanding the thermal-mechanical coupling phenomena of nanodevices and the complex process of fullerenes' formation.

Carbon Material from Natural Sources as an Anode in Lithium Secondary Battery

  • Bhardwaj, Sunil;Sharon, Maheshwar;Ishihara, T.;Jayabhaye, Sandesh;Afre, Rakesh;Soga, T.;Sharon, Madhuri
    • Carbon letters
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    • v.8 no.4
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    • pp.285-291
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    • 2007
  • Carbon materials of various morphologies were synthesized by pyrolysis of Soap-nut seeds (Sapindus mukorossi), Jack Fruit seeds (Artocarpus heterophyllus), Date-seeds (Phoenix dactylifera), Neem seeds (Azadirachta indica), Tea leaves (Ehretia microphylla), Bamboo stem (Bambusa bambus) and Coconut fiber (Cocos nucifera), without using any catalyst. Carbon materials thus formed were characterized by SEM XRD and Raman. Carbon thus synthesized varied in size (in ${\mu}m$) but all showed highly porous morphology. These carbon materials were utilized as the anode in Lithium secondary battery. Amongst the various precursors, carbon fibers obtained from Soap-nut seeds (Sapindus mukorossi) and Bamboo stem (Bambusa bambus), even after $100^{th}$ cycles, showed the highest capacity of 130.29 mAh/g and 92.74 mAh/g respectively. Morphology, surface areas and porosity of carbon materials obtained from these precursors were analyzed to provide interpretation for their capacity to intercalate lithium. From the Raman studies it is concluded that graphitic nature of carbon materials assist in the intercalation of lithium. Size of cavity (or pore size of channels type structure) present in carbon materials were found to facilitate the intercalation of lithium.

Developing a Large-scale Carbon Offset Project Based on Forest Management - In Case of Jin-An Leading Forest Management Zone - (산림탄소상쇄 사업의 흡수량 증대를 위한 대규모 산림경영형 사업모델 개발에 관한 연구 - 진안군 선도 산림경영단지를 중심으로 -)

  • Kim, Young-hwan
    • Journal of Climate Change Research
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    • v.7 no.2
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    • pp.137-142
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    • 2016
  • To achieve large-scale carbon removals, a carbon offset project based on forest management was designed and its carbon stock change was estimated in this study. The project was designed for 874 hectares of forests in the Jin-An Leading Forest Management Zone. For estimating the carbon stock change of the project, the Korean Forest Carbon Standard and VCS (Verified Carbon Standard) methodologies were applied. Three types of management options were considered in the project : extension of rotation age, conversion to productive forests, and conversion to selective harvesting. The estimated carbon removals from the project designed in this study were $259,936tCO_2$ ($8,664tCO_2$ annually), which is 98% of estimated carbon removals from the entire 69 projects currently registered to the Forest Carbon Offset Registry in Korea. The results of this study showed that a large-scale carbon offset project based on forest management could have a huge potential to produce carbon offset credits.