• The Korean Journal of Ceramics
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• 제2권4호
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• pp.221-225
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• 1996

In diamond synthesis by metal film growth method under high pressure and high temperature, the nucleation and growth of diamond was observed dependent on the carbon source variation from graphite powder to the heat treated powders of lamp black carbon. At the low driving force condition near equilibrium pressure and temperature line, nucleation of diamond did not occur but growth of seed diamond appeared in the synthesis from lamp black carbon while both nucleation and growth of diamond took place in the synthesis from graphite. Growth morphology change of diamond occurred from cubo-octahedron to octahedron in the synthesis from graphite but very irregular growth of seed diamond occurred in the synthesis from lamp block carbon. Lamp black carbon transformed to recrystallized graphite first and very nucleation of diamond was observed on the recrystallized graphite surface. Growth morphology of diamond on the recrystallized graphite was clear cubo-octahedron even at higher pressure departure condition from equilibrium pressure and temperature line.

• Carbon letters
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• 제11권2호
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• pp.90-95
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• 2010

Carbon materials such as graphite and graphene exhibit high electrical conductivity. We examined the electrical conductivity of synthetic and natural graphene powders after the chemical reduction of synthetic and natural graphite oxide from synthetic and natural graphite. The trend of electrical conductivity of both graphene (synthetic and natural) was compared with different graphite materials (synthetic, natural, and expanded) and carbon nanotubes (CNTs) under compression from 0.3 to 60 MPa. We found that synthetic graphene showed a marked increment in electrical conductivity compared to natural graphene. Interestingly, the total increment in electrical conductivity was greater for denser graphite; however, an opposite behavior was observed in nanocarbon materials such as graphene and CNTs, probably due to the differing layer arrangement of nanocarbon materials.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1390-1397
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• 2019

SiC coating and SiC/glassy carbon composite coating were prepared on IG-110 nuclear graphite (Toyo Tanso Co., Ltd., Japan) to strengthen its inertness to molten fluoride salt used in molten salt reactor (MSR). Two kinds of modified graphite were obtained and correspondingly named as IG-110-1 and IG-110-2, which referred to modified IG-110 with a single SiC coating and a SiC/glassy carbon composite coating, respectively. Both structure and property of modified graphite were carefully researched and contrasted with virgin IG-110. Results indicated that modified graphite presented better comprehensive properties such as more compact structure and higher resistance to molten salt infiltration. With the protection of coatings, the infiltration amounts of fluoride salt into modified graphite were much less than that into virgin IG-110 at the same circumstance. Especially, the infiltration amount of fluoride salt into IG-110-2 under 5 atm was merely 0.26 wt%, which was much less than that into virgin IG-110 under 1.5 atm (13.5 wt%) and the critical index proposed for nuclear graphite used in MSR (0.5 wt%). The SiC/glassy carbon composite coating gave rise to highest resistance to molten salt infiltration into IG-110-2, and thus demonstrated it could be a promising protective coating for nuclear graphite used in MSR.

• 전기화학회지
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• 제12권2호
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• pp.162-166
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• 2009

탄소 피복된 Si/Cu 분말을 기계적인 볼-밀링(ball-milling) 방법과 고온에서 탄화수소가스 분해 방법에 의해 제조하여 리튬이차전지용 음극으로 사용하였고 이에 대한 전기화학적 거동을 조사하였다. 천연흑연(natural graphite)을 이용하여 탄소 피복된 Si/Cu/graphite 복합체 음극소재를 제조하였으며 천연흑연 음극소재와 전기화학적 특성을 비교하였다. 탄소 피복된 Si/Cu 음극의 가역적 비용량은 초기 10 싸이클까지 지속적인 증가를 나타냈다. 탄소 피복된 Si/Cu/graphite 복합체 음극의 가역적 비용량은 $0.25mA/cm^2$ 전류밀도에서 450mAh/g이고 초기 싸이클 효율은 81.3%로 나타났다. 복합체 음극의 싸이클 성능은 가역적인 비용량값을 제외하고 천연흑연 음극과 유사하게 나타났다.

• Journal of Electrochemical Science and Technology
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• 제2권2호
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• pp.116-123
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• 2011

Herein, a novel preparation method of highly homogeneous carbon-silicon composite materials was presented. In contrast to conventional solvent evaporation method, a milled silicon-graphite or its oxidized material were directly reacted with petroleum-derived pitch precursor. After thermal reaction under high pressure, pitch-graphite-silicon composite was prepared. Carbon-graphite-silicon composite were prepared by an air-oxidization and following carbonization. From energy dispersive spectroscopy, it was observed that small Si particles were highly embedded within carbon, which was confirmed by disappearance of Si peaks in Raman spectra. Furthermore, X-ray diffraction and Raman spectra revealed that carbon crystallinity decreased when the strongly oxidized silicon-graphite was added, which was probably due to oxygen-induced cross-linking. From the anode application in lithium ion batteries, carbon-graphite-silicon composite anode displayed a high capacity ($565\;mAh\;g^{-1}$), a good initial efficiency (68%) and an good cyclability (88% retention at 50 cycles), which were attributed to the high dispersion of Si particles within cabon. In case of the strongly oxidized silicongraphite addtion, a decrease of reversible capacity was observed due to its low crystallinity.

• Bulletin of the Korean Chemical Society
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• 제29권6호
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• pp.1121-1124
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• 2008

A carbon composite was synthesized by mechanical mixing of ball-milled graphite and PVC powders, followed by pyrolysis reaction of PVC. Natural graphite ball milled under atmosphere of argon or air leads to a disordered structure. It appears that the electrochemical lithium intercalation reaction is dependent on the atmosphere in which the graphite is ball milled. The carbon composite obtained using air-milled graphite shows a high reversible capacity and high initial coulombic efficiency compared to argon-milled graphite. This is attributed to the enhanced thermal stability of a disordered structure in the air milled sample. For the one with air-milled graphite, the disordered structure is maintained during heat treatment, while argon-milled graphite is partially crystallized.

• 한국응용과학기술학회지
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• 제20권2호
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• pp.130-140
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• 2003

In order to improve the lithium ion battery's performance, the carbon nanofibers were introduced to the anode electrode fabricated with natural graphite particles. The influence of structural adjustment of the particles by the introduction method of carbon nanofibers and the content of carbon nanofibers on the electrical property and charge/discharge characteristics of the electrode were investigated. The electrode fabricated with the mixture of 10 wt% of carbon nanofibers grown separately and 90 wt% of graphite particles showed an excellent discharge capacity of 400 mAh/g and the improved cycle performance. The improved performance could be explained by that the carbon nanofibers shortened and uniformly distributed on the surface of graphite particles by ball milling increased the stability for the intercalation/deintercalation of lithium ion and increased the electrical conductivity due to the closed packing between graphite particles.

• 한국토양비료학회지
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• 제36권2호
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• pp.86-91
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• 2003

흑연이나 활성탄등의 탄소물질이 작물의 생육을 촉진하며 유용 토양미생물의 생육을 촉진하는것으로 알려져 있어 본 실험에는 제철공정에서 재활용, 정제된 흑연을 상토의 첨가제로 시용하여 벼의 생육과 수량에 미치는 영향에 대하여 실험하였다. 실험결과, 이앙기의 생육은 대조구와 비교하여 0.1% 흑연 첨가구에서 생육 촉진효과가 보였으며 이앙후 처리구별 생육의 차이는 그다지 보이지 않았다. 다만 0.1% 첨가구에서 육묘한 벼의 수량은 특별한 통계적 유의성을 보이지 않았으나 약 1%정도 증수되었다.

• Carbon letters
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• 제14권1호
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• pp.40-44
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• 2013

The bipolar plate is the most important and most costly component of proton exchange membrane fuel cells. The development of a suitable low density bipolar plate is scientifically and technically challenging due to the need to maintain high electrical conductivity and mechanical properties. Here, bipolar plates were developed from different particle sizes of natural and expanded graphite with phenolic resin as a polymeric matrix. It was observed that the particle size of the reinforcement significantly influences the mechanical and electrical properties of a composite bipolar plate. The composite bipolar plate based on expanded graphite gives the desired mechanical and electrical properties as per the US Department of Energy target, with a bulk density of 1.55 $g.cm^{-3}$ as compared to that of ~1.87 $g.cm^{-3}$ for a composite plate based on natural graphite (NG). Although the bulk density of the expanded-graphite-based composite plate is ~20% less than that of the NG-based plate, the I-V performance of the expanded graphite plate is superior to that of the NG plate as a consequence of the higher conductivity. The expanded graphite plate can thus be used as an electromagnetic interference shielding material.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.254.2-254.2
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• 2013

Cu wire 발열패드는 대중화된 히터로 많이 이용되지만 높은 소비전력(70 w이상)으로 에너지 효율을 중요시 하는 미래 소재로는 적합하지 않아 효율이 높은 발열 소재의 연구가 이루어지고 있다. 이에 본 실험에서 Graphite표면에 Amide 기능화를 유도된 Carbon nanotube (Electrical Conductivity $10^5$ s/cm, Thermal Conductivity >3,000 w/mk)를 분산 시켜, Graphite의 우수한 전기 전도도의 특성을 이용할 뿐만 아니라 Carbon nanotube의 접착 특성을 통해 물리적 특성을 향상시켜 면상발열체의 도막 특성 향상뿐만 아니라 효율적 발열을 유도 하고자 한다.