• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1842-1848
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• 2002

Although DLC coatings have good tribological properties, these are dependant on the deposition method, the property of contact surface, and test condition. Humidity, which has little influence on tribological behavior in macro scale, is an important factor of tribological behavior in small devices like MEMS. The objective of this study is to investigate the tribological behavior of DLC coatings with particular attention to their wettability at various humidities. DLC coatings were deposited on Si substrates and tested using a reciprocating friction tester against Si$_3$N$_4$balls at various humidities. The results showed that the tribological behavior of DLC coatings was dependant on relative humidity and wettablility of DLC coatings. Friction coefficient at high relative humidity was higher thar that at low relative humidity. The tungsten-containing DLC coatings had a good wear resistance at low relative humidity whereas DLC coatings derived from argon(Ar)+cesium(Cs) gases showed a good wear resistance at high relative humidity.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.656-662
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• 2015

In the present study, multi-layered Si DLC (Silicon Diamond-Like Carbon) coatings with HMDSO (Hexamethyldisiloxane) buffer layers are applied on SKD 11 substrates by PECVD (Plasma Enhanced Chemical Vapor Deposition) with different HMDSO gas flow rates, while the gas flow rate of $C_2H_2$ is fixed to enhance the electric resistivity of forming dies for electrically assisted forming. The HMDSO buffer layer is introduced to increase adhesion between the base metal and Si-DLC layers. The result of evaluation of electric resistivity and adhesion strength shows that the properties are affected by the flow rate of HMDSO, while the flow rate of 80 sccm results in the coating with the highest electric resistivity and adhesion strength among the selected flow rates.

• Journal of Industrial Convergence
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• v.21 no.8
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• pp.35-42
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• 2023

Recently, electronic devices with bendable electronic devices based on flexible substrates are being sold, and therefore, the purpose of this study is to evaluate the possibility of flexible substrates of conductive transparent tapes. As a transparent electrode, carbon nanotube (CNT) was formed by the coating method developed by the research team, and samples coated up to 5 times were fabricated. The surface resistance and transmittance of the substrate were measured, and both resistance and transmittance decreased as the number of CNT coatings increased. After the tape was detached from the glass, the surface resistance slightly increased in all samples, and the transmittance increased by about 10% in all measured wavelength ranges because the glass was removed. Next, the tape coated with CNT twice was used to a bending test 20,000 times under the condition of a radius of curvature of 2 mm. The electrical and optical properties before and after bending did not change, which means that there was no change in CNT properties due to bending.

• Composites Research
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• v.14 no.1
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• pp.15-21
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• 2001

The pressing roller was designed and manufactured with high modulus carbon fiber composite material to exploit the high specific stiffness of the composite material. the optimal stacking sequence for the pressing roller was obtained from the FE analysis and the shape of the rubber coating layer was determined based on the calculated deflection for the uniform pressure on the film along the axial length of the pressing roller. Then the static deflection of the manufactured composite pressing roller was experimentally evaluated in comparison with analysis result and dynamic characteristics were measured through vibrational test.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.5
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• pp.430-437
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• 2004

This paper is intended as an investigation of study on the thermal and electrical characteristics of the carbon heating element. In this experimentation, the electric material used is the crystalline graphite a kind of natural graphite. The bentonite is used to solidify the heating element and the vacuum furnace is used for sintering it. It is noted that the natural drying time should be at least 58 hours. The plating of the electric pole with the electroless nickel showed the lowest contact resistance among others. The resistance shows linear variation with regard to length. For the insulation and resolution, the glaze coating is best with 80% of water content. The temperature rising characteristic of the heating element is better than sheath heater saving 43% of rising time. The correlation equation for temperature was obtained with the electric power.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1007-1015
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• 1999

The Si3N4 composites reinforced with carbon-coated SiC whiskers were fabricated by hot-pressing at 180$0^{\circ}C$ for 2 hours to examine the effects of carbon-coated whiskers on the mechanical properties of SiC whisker reinforced Si3N4 composites. The flexural strength of the Si3N4 composites and Si3N4 monolith respectively. The weak interfacial bond between carbon-coated SiC whiskers and Si3N4 matrix which enhances the crack deflection and whisker pull-out could contribute to the improvement of mechanical properties of the composites.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.238.1-238.1
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• 2005

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.2
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• pp.116-123
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• 2009

Carbon black, activated carbon and carbon nanotube have been used as supporting materials for precious metal catalysts used in fuel cell electrodes. One-step flame synthesis method is used to coat 2-5nm Pt dots on flame-generated carbon particles. By adjusting flame temperature, gas flow rates and resident time of particles in flame, we can obtain Pt/C nano catalyst-support composite particles. Additional injection of hydrogen gas facilitates pyrolysis of Pt precursor in flame. The size of as-incepted Pt dots increases along the flame due to longer resident time and sintering in high temperature flame. Surface coverage and dispersion of the Pt dots is varied at different sampling heights and confirmed by Transmission electron microscopy (TEM), Energy-dispersive spectra (EDS) and X-ray diffraction (XRD). Crystalinity and surface bonding groups of carbon are investigated through X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.

• Tribology and Lubricants
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• v.35 no.6
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• pp.362-368
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• 2019

In this study, mechanical and tribological properties were investigated by varying the process temperature (50, 100, 125 and 150℃) to reduce internal stress. The internal stress reduction by thermal dissociation ta-C coating film with increasing temperature is confirmed through the curvature radius of the ta-C coating according to the temperature of the SUS plate. As the coating temperature increased, the mechanical properties (hardness, modulus, toughness) deteriorated, which is in agreement with the Raman analysis results. As the temperature increased, the sp² phase ratio increased owing to the dissociation of the sp³ phase. The friction and wear properties are related to the process temperature during ta-C coating. Low friction and wear properties are observed in high hardness samples manufactured at 50℃, and wear resistance properties decreased with increasing temperature. The contact area is expected to increase owing to the decrease of hardness(72 GPa to 39 GPa) and fracture toughness with increasing temperature which accelerated wear because of the debris generated. It was confirmed that at process temperature of over than 100℃, the bond structure of the carbon film changed, and the effect of excellent internal stress was reduced. However, the wear resistance simultaneously decreased owing to the reduction in fracture toughness. Therefore, in order to increase industrial utilization, optimum temperature conditions that reduce internal stress and retain mechanical properties.