• Carbon letters
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• 제16권1호
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• pp.34-40
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• 2015

In this study, in order to improve the thermal and electrical properties of epoxy/graphene nanoplatelets (GNPs), surface modifications of GNPs are conducted using silane coupling agents. Three silane coupling agents, i.e. 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane (ETMOS), 3-glycidoxypropyltriethoxysilane (GPTS), and 3-glycidoxypropyltrimethoxysilane (GPTMS), were used. Among theses, GPTMS exhibits the best modification performance for fabricating GNP-incorporated epoxy composites. The effect of the silanization is evaluated using transmission electron microscopy (TEM), scanning electron microscopy, thermogravimetric analysis, and energy dispersive X-ray spectroscopy. The electrical and thermal conductivities are characterized. The epoxy/silanized GNPs exhibits higher thermal and electrical properties than the epoxy/raw GNPs due to the improved dispersion state of the GNPs in the epoxy matrix. The TEM microphotographs and Turbiscan data demonstrate that the silane molecules grafted onto the GNP surface improve the GNP dispersion in the epoxy.

• 한국표면공학회지
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• 제44권3호
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• pp.75-81
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• 2011

Growth behaviors of iron-nitride on S45C steels at low pressure gas nitriding were examined. Surfaces of the steels covered with fine and porous oxide during the pre-oxidation using $N_2O$ gas. Well faceted particles connected with them were observed after 1 min nitriding. They grew steadily and filled inter-pores during additional nitriding process. From the X-ray diffraction analysis, ${\gamma}'$-iron nitride was dominantly formed at the initial stage but the amount of ${\varepsilon}$-iron nitride was rapidly increased as nitriding treatment time. The porous layer was formed on the particles and thickened up to half of nitride layer after 60 min nitriding. The observed growth behaviors were discussed in internal stress related with volume expansion involved in transforming from iron to iron-nitrides.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.384.2-384.2
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• 2014

We investigated the electrical and structural properties of chemical vapor deposition (CVD)-grown graphene and post treated by O2 plasma. For the patterning of graphene, the plasma technology is generally used and essential for etching of graphene. But, the cautious O2 plasma treatments are required to avoid the damage in graphene edge which can be the harmful effects on the device performance. To analyze the effects of plasma treatment on structural properties of graphene, the change of surface morphology of graphene are measured by scanning electron microscope and atomic force microscope before and after plasma treatment. In addition, the binding energy of carbon and oxygen are measured through to X-ray photoelectron spectroscopy. After plasma treatment, the severe changes of surface morphology and binding energy of carbon and oxygen were observed which effects on the change of sheet resistance. Finally, to analyze of graphene characteristics, we measured the Raman spectroscopy. The measured results showed that the plasma treatment makes the upward of D-peak and downward of G'-peak by elevated power of plasma.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권8호
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• pp.325-329
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• 2003

Effects of thermal treatment on the structural properties of diamond-like carbon (DU) films were examined. The DLC films were deposited by using a modified filtered cathodic vacuum arc (FCVA) deposition system and by varying the negative substrate bias voltage, deposition time, and nitrogen flow rate. Thermal treatment on DLC films was performed using a rapid thermal annealing (RTA) process at $600^{\circ}C$ for 2min. Raman spectroscopy, x-ray photoemission spectroscopy (XPS), atomic force microscope (AFM), and surface profiler were used to characterize the I$_{D}$I$_{G}$ intensity ratio, sp$^3$ hybrid carbon fraction, internal stress, and surface roughness. It was found for all the deposited DLC films that the RTA-treatment results in the release of internal compressive stress, while at the same time it leds to the decrease of sp$^3$ fraction and the increase of I$_{D}$I$_{G}$ intensity ratio. It was also suggested that the thermal treatment effect on the structural property of DLC films strongly depends on the diamond-like nature (i.e., sp$^3$ fraction) of as-deposited film.ed film.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1606-1608
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• 1997

We have synthesized PPP from benzen by chemical reaction. And then disordered carbon materials were obtained by heating-treating PPP in a nitrogen atmosphere for 1, 4, 8 and 12 hour at $700^{\circ}C$. The carbon prepared by heat treatment showed a broad x-ray diffraction peak around $2{\theta}=20^{\circ}$ having a property of disordered carbon. Carbon electrodes were charged and discharged at a current density of $0.25mA/cm^2$. In the result, PPP-based carbon obtained at $700^{\circ}C$ for 8h showed 605mAh/g of first discharge capacity and had a small hysteresis characteristic.

• 동력기계공학회지
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• 제11권1호
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• pp.121-126
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• 2007

This study aims at investigating the effect of heat treatment conditions on the dry sliding wear behavior of thermally sprayed Ni-based self-flux alloy coatings. Ni-based self-flux alloy powders were sprayed onto a carbon steel substrate and then heat-treated at 700, 800, 900 and $1000^{\circ}C$ for 30 minutes in a vacuum furnace. Dry sliding wear tests were performed using sliding speed of 0.4 m/s and applied load of 6 N. AISI 52100 ball(diameter 8 mm) was used as counterparts. Microstructure and wear behavior of both as-sprayed and heat-treated Ni-based self-flux alloy coatings were studied using a scanning electron microscope(SEM), energy dispersive X-ray spectroscopy(EDX), electron probe micro-analysis(EPMA) and X-ray diffraction(XRD). It was revealed that microstructure and wear behavior of thermally sprayed Ni-based self-flux alloy coatings were much influenced by heat treatment conditions.

• 공업화학
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• 제27권5호
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• pp.472-477
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• 2016

본 연구에서는 전류밀도 변화에 따른 탄소섬유의 양극산화 처리가 탄소섬유 표면과 탄소섬유 강화 복합재료의 기계적 계면결합력에 미치는 영향을 고찰하였다. 양극산화 처리된 탄소섬유 표면 특성은 원자간력 현미경(Atomic force microscope, AFM)과 전계방사형 주사전자현미경(Field emission-scanning electron microscope, FE-SEM), 적외선 분광법(Fourier transform infrared spectroscopy, FT-IR) 및 X선 광전자 분광법(X-ray Photoelectron Spectroscopy, XPS)으로 분석하였으며, Short beam 전단시험을 통해 표면처리에 따른 탄소섬유 강화 복합재료의 계면 전단강도를 측정하였다. 실험 결과 전류밀도가 증가함에 따라 탄소섬유 표면의 거칠기와 산소관능기의 함량의 증가와, 탄소섬유 강화 복합재료의 층간전단강도(Interlaminar shear strength, ILSS)의 향상 및 페놀릭 하이드록실 그룹과의 비례관계를 확인하였다. CF-2.0 시편의 층간전단강도는 87.9 MPa로 CF-AS 시편에 비해 약 4% 증가하였는데, 이러한 결과는 양극산화 처리가 산소관능기와 탄소섬유 표면 거칠기의 증가를 유도하여 탄소섬유와 수지의 계면 결합력이 증가된 것으로 판단된다. 그중 층간전단강도와 비례관계인 페놀릭 하이드록실 그룹은 탄소섬유 강화 복합재료의 계면결합력을 향상시키는 중요한 요소라 판단된다.

• Journal of Ceramic Processing Research
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• 제19권6호
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• pp.499-503
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• 2018

In this paper, cobalt embedded in nitrogen and sulfur co-doped carbon nanotubes (CoNSTs) were synthesized for oxygen reduction reaction (ORR) catalysts. The CoNSTs were prepared through a facile heat treatment method without any templates. Different amounts of the metal salt were employed to examine the physicochemical and electrochemical properties of the CoNSTs. The CoNSTs showed the bamboo-like tube morphology with the encased Co nanoparticles in the tubes. Through the x-ray photoelectron spectroscopy analysis, the catalysts exhibited different chemical states of the nitrogen and sulfur species. As a result, the CoNST performed high activity toward the ORR in an acidic condition with the onset potential of 0.863 V (vs. reversible hydrogen electrode). It was clearly demonstrated from the electrochemical characterizations that the quality of the nitrogen and sulfur species significantly influences the ORR activity rather than the total amount of the dopants.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집
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• pp.1-2
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• 2008

Thick films of Carbon fiber were prepared by a heating element of plan shape made in Darin co.. We have investigated surface morphology of the specimen depending on second heat-treatment temperatures. X-ray diffraction patterns of Carbon fiber thick films show that the specimen heat treated below $600^{\circ}C$ was an amorphous phase and the one heat treated above $1100^{\circ}C$ forms a poly-crystallization. Scanning electron microscope(SEM) image of Carbon fiber thick films of the specimen heat treated in between 900 and $1100^{\circ}C$ shows a grain growth. At $1100^{\circ}C$, the specimen stops grain-growing and becomes a poly-crystallization.

• Carbon letters
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• 제12권3호
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• pp.167-170
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• 2011

Petroleum pitch-based activated carbons (ACs) were obtained in this work from a combination of pretreatment with different amounts of potassium permanganate ($KMnO_4$) and chemical activation with potassium hydroxide. The surface characteristics of the pitch after the $KMnO_4$ pretreatment were characterized by means of Fourier transform infrared spectroscopy (FT-IR). The structural characteristics of the pitch after the $KMnO_4$ pretreatment were determined by means of X-ray diffraction. The influence of the $KMnO_4$ treatment on the textural properties of the petroleum pitch-based ACs was investigated by means of $N_2$/77K adsorption isotherms. The investigation also involved the use of the Brunauer-Emmett-Teller equation and the Dubinin-Radushkevich method. The FT-IR results show that the pretreatment promotes the formation of surface oxygen functionalities and leads to an increase of the interplanar distance ($d_{002}$) of the functional groups induced between carbon layers. Moreover, the specific surface area of the pitch-based ACs increases in proportion to the amount of $KMnO_4$ pretreatment and reaches its highest value of 2334 $m^2$/g with 2 g of $KMnO_4$ because the surface oxygen groups of the pitch act as an active site during chemical activation.