• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.747-750
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• 2000

In this work, we investigated the dependence of optical and electrical properties of amorphous hydrogenated SiC (a-SiC:H) films on annealing temperature(T$\sub$a/). The a-SiC:H films were deposited by PECVD(plasma enhanced vapor deposition) on coming glass, p-type Si(100) wafer using SiH$_4$+CH$_4$+N$_2$gas mixture. The experimental results have shown that the optical energy band gap(E$\sub$g/) of the a-SiC thin films unchanged in the range of T$\sub$a/ from 400$^{\circ}C$ to 600$^{\circ}C$. The Raman spectrum of the thin films, annealed at high temperatures, has shown that graphitization of carbon clusters and micro-crystalline silicon occurs. The current-voltage characteristics have shown good electrical properties at the annealed films.

• Carbon letters
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• 제4권1호
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• pp.24-30
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• 2003

In this study, densified 4D carbon/carbon composites were made from carbon fiber and coal tar pitch through the process of pressure impregnation and carbonization and then followed by carbonization and graphitization. To improve the oxidative resistance of the prepared carbon/carbon composites, the surface of carbon/carbon composites was coated on SiC by the pack cementation method. The SiC coated layer was created by depending on the constitution of pack powder, and reaction time of pack-cementation. The morpology of crystalline and texture of these SiC coated carbon/carbon composites were investigated by XRD, SEM/EDS observation. So the coating mechanism of pack-cementation process was proposed. The oxidative res istance were observed through the air oxidation test, and then the optimal condition of pack cementation was found by them. Besides, the oxidative mechanism of SiC formed was proposed through the observation of SiC coated surface, which was undergone by oxidation test.

• 한국진공학회지
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• 제4권S2호
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• pp.34-39
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• 1995

we have studied the possibility of n-type doping in diamond and DLC films. After ion doping of either p-type or n-type, the electrical conductivities were remarkably increased and conductivity activation energies were decreased. The Raman intensity at 1330 cm-1 decreases slightly by ion doping of $7.2\times 10^{16}\; \textrm{cm}^{-2}$. The increase in conductivity by ion doping appears to be arised from the combined effects by substitutional doping and graphitization by ion damage.

• 전기화학회지
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• 제2권4호
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• pp.221-226
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• 1999

조직의 형태와 불순물의 함량이 서로 다른 2종류의 침상 코크스(needle cokes, NC)를 $2000\~3000^{\circ}C$온도범위에서 열처리한 후 이들의 흑연화도, 분쇄하였을 때의 입자크기, 크기분포 및 표면적을 측정하였고 리튬 2차전지의 음극특성을 조사하였다. 두 시료 모두 열처리 온도가 증가함에 따라 흑연화도가 증가하였으나, NC-B는 불순물의 영향과 분자간의 배열이 적은 모자익 조직을 포함하고 있기 때문에 흑연화도가 낮게 나타났다. 동일한 조건에서 분쇄하였을 때 입자의 평균크기는 흑연화도와 비례하였고 표면적은 반비례하였다. 흑연화도가 큰 시료일수록 입자분포의 균일도는 감소하였다 열처리 온도에 따른 음극 특성을 조사하였을 때, 2000"C까지는 결정결함을 포함하는 탄소질 층간(carbonaceous interlayers)의 감소로 인해 용량이 감소하였으나 그 이상의 온도에서는 흑연질 층간(graphitic interlayers)의 성장으로 용량이 다시 증가하였다. 분쇄한 시료는 파단면 표면에 부정합 구조가 생성되어 1.0 V이상에서 기울기를 갖는 방전곡선을 보여 주었으나, 이는 거듭된 충방전과 재열처리에 의해 0.25 V 이하에서 방전되는 흑연질 구조로 전환되었다.

• 한국분말재료학회지
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• 제16권6호
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• pp.416-423
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• 2009

Diamond/SiC composites are appropriate candidate materials for heat conduction as well as high temperature abrasive materials because they do not form liquid phase at high temperature. Diamond/SiC composite consists of diamond particles embedded in a SiC binding matrix. SiC is a hard material with strong covalent bonds having similar structure and thermal expansion with diamond. Interfacial reaction plays an important role in diamond/SiC composites. Diamond/SiC composites were fabricated by high temperature and high pressure (HPHT) sintering with different diamond content, single diamond particle size and bi-modal diamond particle size, and also the effects of composition of diamond and silicon on microstructure, mechanical properties and thermal properties of diamond/SiC composite were investigated. The critical factors influencing the dynamics of reaction between diamond and silicon, such as graphitization process and phase composition, were characterized. Key factor to enhance mechanical and thermal properties of diamond/SiC composites is to keep strong interfacial bonding at diamond/SiC composites and homogeneous dispersion of diamond particles in SiC matrix.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.131.1-131.1
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• 2010

고분자연료전지(PEMFC)에서 기체확산층(GDL)은 다공성의 카본 종이/천 위에 마이크로한 다공층을 가치는 구조로 촉매층을 지지하고 촉매층과 분리판 사이의 전류전도체 역할을 한다. 또한 촉매층에 연료와 공기 확산 및 생성된 물의 통로 역할을 하며 소수성인 전기전도성 물질로 이루어져 있다. 현재 연료전지에 쓰이는 가스확산층은 대부분 국외 회사에서 제조 수입 사용하는 현황이고 국내에서는 협진 I&C가 연구하고 있으나 상용화는 아직 이루어지지 않고 있다. 본 연구는 탄소섬유의 전도성을 개선하고자 탄소섬유 표면에 금속코팅 시 최적의 접촉계면유지를 위한 표면처리 방법 및 공정을 조사 분석 후 최적 개선방법(농도/온도/압력/시간)을 설정하고자 하였다. 또한 선정된 공정인자별 수준별 시험 후 샘플링 된 시료를 토대로 금속물질이 탄소섬유 표면에 코팅(도금)된 금속-탄소섬유를 대하여 평가하여 최적화시키고자 탄소섬유로부터 carbon paper GDL의 모재를 개발할 계획이다. 앞에서 설명한 바와 같이 탄소섬유를 이용하여 paper making, resin impregnation, molding, carbonization/graphitization의 제조공정을 거쳐 paper형태의 GDL을 생산 및 평가하고자 하였다.

• 한국전기전자재료학회논문지
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• 제19권7호
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• pp.618-623
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• 2006

Hydrogenated Diamond-like carbon (DLC) films were prepared by the radio frequency plasma enhanced chemical vapor deposition (RF PECVD) method on silicon substrates using methane $(CH_4)$ and hydrogen $(H_2)$ gas. The wear track on the DLC films was examined after the ball-on disk (BOD) measurement with a Raman mapping method. The BOD measurement of the DLC films was performed for 1 to 3 hours with a 1-hour step time. The sliding traces on the hydrogenated DLC film after the BOD measurement were also observed using an optical microscope. The surface roughness and cross-sectional images of the wear track were obtained using an atomic force microscope (AFM). The novel Raman mapping method effectively shows the graphitization of DLC films of $300{\mu}m\times300{\mu}m$ area according to the sliding time by G-peak positions (intensities) and $I_D/I_G$ ratios.

• 한국세라믹학회지
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• 제43권7호
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• pp.439-444
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• 2006

Artificial graphite generally manufactured by carbonization sintering of shape-body of kneaded mixture using granular cokes as filler and pitch as binder, going through pitch impregnation process if necessary and finally applying graphitization heat treatment. Graphite materials are used for core internal structural components of the High-Temperature Gas-cooled Reactors (HTGR) because of their excellent heat resistibility and resistance of crack progress. The HTGR has a core consisting of an array of stacked graphite fuel blocks are machined from IG-110, a high-strength, fine-grained isotropic graphite. In this study, crack stabilization and micro-structures were measured by bend strength and fracture toughness of isotropic graphite grade IG-110. It is important to the reactor designer as they may govern the life of the graphite components and hence the life of the reactor. It was resulted crack propagation, bend strength, compressive strength and micro-structures of IG-110 graphite by scanning electron microscope and universal test machine.

• 열처리공학회지
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• 제23권2호
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• pp.83-89
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• 2010

Diamond-like carbon (DLC) coating was studied to be a good tribological problem-solver due to its low friction characteristics and high hardness. However, generally hydrogenated DLC film has shown a weak thermal stability above $300^{\circ}C$. However, the silicon doping DLC process by DC pulse plasma enhanced chemical vapor deposition (PECVD) for the new DLC coating which has a good characterization with thermal stability at high temperature itself has been observed. And we were discussed a process for optimizing silicon content to promote a good thermal stability using various tetramethylsilane (TMS) and methane gas at high-temperature. The chemical compositions of silicon-containing DLC film was analyzed using X-ray photoelectron spectroscopy (XPS) before and after heat treatment. Raman spectrum analysis showed the changed structure on the surface after the high-temperature exposure testing. In particular, the hardness of silicon-containing DLC film showed different values before and after the annealing treatment.

• Tribology and Lubricants
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• 제10권4호
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• pp.13-26
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• 1994

Effects of resin contents, number of carbonization, graphitization, sliding speed, and oxidation on friction and wear behavior of carbon/carbon composite materials were investigated. Friction and wear tests were carried out under various sliding conditions. An experimental setup was designed and built in the laboratory. Stainless steel disks were used as the counterface material. Friction coefficient, emperature, and wear factor were measured with a data acquisition system. Wear surfaces were observed by the scanning electron microscope. It has been shown that the average friction coefficient was increased with the sliding speed in the range of 1.43~6.10 m/s, but it as decreased in the range of 6.10~17.35 m/s. Specimens prepared by different numbers of carbonization. showed variations in friction coefficient and friction coefficient of the graphitized specimen was the highest. Friction coefficients depended on contribution of the plowing and adhesive components. As the number of carbonization was increased, wear factor was reduced. Wear factor of the graphitized specimens dropped further. In the case of graphitized specimens, sliding speed had a large influence on wear behavior. When the tribological experiments were conducted in nitrogen atmosphere, the wear factor was decreased to two thirds of the wear factor obtained in air. It is obvious that the difference was affected by oxidation. Results of friction and wear tests were applied to a neural network system based on the backpropagation algorithm. A neural network may be a valuable tool for prediction of tribological behavior of the carbon/carbon composite material if ample data are present.