• 대한화학회지
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• 제60권5호
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• pp.299-309
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• 2016

In this study, the physicochemical and electrochemical properties of carbon nanomaterials and synthesized nano-carbon/Si composites were studied. The nano-carbon/Si composites were ball-milled to a nano size and coated with pyrolytic carbon using Chemical Vapor Deposition (CVD). They were then finely mixed with respective nano-carbon materials. The physicochemical properties of samples were analyzed using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Raman spectroscopy, X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and surface area analyzer. The electrochemical characteristics were investigated using the galvanostatic charge-discharge and cyclic voltammetry (CV) measurements. Three-electrode cells were fabricated using the carbon nanomaterials and nano-carbon/Si composites as anode materials and LiPF₆ and LiClO₄ as electrolytes of Li secondary batteries. Reversibility using LiClO₄ as an electrolyte was superior to that of LiPF₆ as the electrolyte. The initial discharge capacities of nano-carbon/Si composites were increased compared to the initial discharge capacities of nano-carbon materials.

• Carbon letters
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• 제9권4호
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• pp.316-323
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• 2008

The factors that influence ablation resistance in fiber composites are properties of the reinforced fiber and matrix, plugging quantity of fiber, geometrical arrangement, crack, pore size, and their distributions. To examine ablation resistance according to distribution of crack and pore size that exist in carbon/carbon composites, this study produced various sizes of unit cells of preforms. They were densified using high pressure impregnation and carbonization process. Reinforced fiber is PAN based carbon fiber and composites were heat-treated up to $2800^{\circ}C$. The finally acquired density of carbon/carbon composites reached more than $1.932\;g/cm^3$. The ablation test was performed by a solid propellant rocket engine. The erosion rate of samples is below 0.0286 mm/s. In conclusion, in terms of ablation properties, the higher degree of graphitization is, the more fibers that are arranged vertically to the direction of combustion flame are, and the less interface between reinforced fiber bundle and matrix is, the better ablation resistance is shown.

• Carbon letters
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• 제5권4호
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• pp.164-169
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• 2004

Carbon-ceramic composites refer to a special class of carbon based materials which cover the main drawbacks of carbon, particularly its proneness to air oxidation, while essentially retaining its outstanding properties. In the present paper, the authors report the results of a systematic study made towards the development of C-SiC-$B_4C$ composites, which involves the effects of compositional parameters, namely, carbon-to-ceramic and ceramic-to-ceramic ratios, on the oxidation behaviour as well as other characteristics of these composites. The C-SiC-$B_4C$ composites, heat-treated to $1400^{\circ}C$, have shown that their oxidation behaviour at temperatures of 800~$1200^{\circ}C$ depends jointly on the total ceramic content and the SiC : $B_4C$ ratio. Good compositions of C-SiC-$B_4C$ composites exhibiting zero weight loss in air at temperatures of 800~$1200^{\circ}C$ for periods of 4~9 h, have been identified. Composites with these compositions undergo a weight gain or a maximum weight loss of less than 3% during the establishment of a protective layer at the surface of carbon in a period of 1~6 h. Significant improvement in the strength of C-SiC-$B_4C$ composites has been observed which increases with an increase in the total ceramic content and also with an increase in the SiC : $B_4C$ ratio.

• 산업경영시스템학회지
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• 제46권3호
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• pp.69-77
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• 2023

Recently, carbon composites have been applied to various fields. However, carbon composites have not been applied to the fishing vessel field due to its structure standards centered on glass composites. In this study, a structural strength evaluation study was conducted for the application of carbon composites in the fishing vessel field. Hull minimum thickness verification test and hull joint verification test were conducted. Compared to glass composites, the verification was based on equivalent or better performance. The results show that carbon composites can reduce the weight by 20% compared to glass composites. For hull joints, it was necessary to increase the thickness of the joint seam by the thickness of the hull to apply carbon composite. Through this study, a standard for the application of carbon composites to fishing vessel can be established.

• Carbon letters
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• 제5권1호
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• pp.1-5
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• 2004

The effects of fiber surface-treatment and sizing on the dynamic mechanical properties of unidirectional and 2-directional carbon fiber/nylon 6 composites by means of dynamic mechanical analysis have been investigated in the present study. The interlaminar shear strengths of 2-directional carbon/nylon 6 composites sized with various thermosetting and thermoplastic resins are also measured using a short-beam shear test method. The result suggests that different surface-treatment levels onto carbon fibers may influence the storage modulus and tan ${\delta}$ behavior of carbon/nylon 6 composites, reflecting somewhat change of the stiffness and the interfacial adhesion of the composites. Dynamic mechanical analysis and short-beam shear test results indicate that appropriate use of a sizing material upon carbon fiber composite processing may contribute to enhancing the interfacial and/or interlaminar properties of woven carbon fabric/nylon 6 composites, depending on their resin characteristics and processing temperature.

• Carbon letters
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• 제14권1호
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• pp.58-61
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• 2013

In this work, the effect of catalysts on the mechanical properties of carbon fibers-reinforced epoxy matrix composites cured by cationic latent thermal catalysts, i.e., N-benzylpyrazinium hexafluoroantimonate (BPH) was studied. Differential scanning calorimetry was executed for thermal characterization of the epoxy matrix system. Mechanical interfacial properties of the composites were studied by interlaminar shear strength (ILSS), critical stress intensity factor ($K_{IC}$), and specific fracture energy ($G_{IC}$). As a result, the conversion of neat epoxy matrix cured by BPH was higher than that of one cured by diaminodiphenyl methane (DDM). The ILSS, $K_{IC}$, $G_{IC}$, and impact strength of the composites cured by BPH were also superior to those of the composites cured by DDM. This was probably the consequence of the effect of the substituted benzene group of BPH catalyst, resulting in an increase in the cross-link density and structural stability of the composites studied.

• Composites Research
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• 제24권5호
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• pp.39-43
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• 2011

탄소나노튜브로 보강된 고분자 수지에 대한 연구는 지난 20년간 활발히 수행되어 왔다. 또한 이를 이용하여 탄소섬유복합재의 물성을 증대시키기 위한 연구도 최근 그 영역을 넓혀가고 있다. 탄소섬유복합재는 탄소섬유의 비약적인 발전으로 섬유 방향의 기계적 물성은 상당히 만족할 만한 수준에 도달했으나, 수지에 의해 좌우되는 기계적 물성은 아직 기대에 못미치고 있다. 특히, 층간의 분리 (delamination)는 탄소섬유복합재의 가장 전형적이며 치명적인 파손의 원인중 하나이다. 이 층간분리에 대한 저항성을 알아보는 모드 1 파괴인성 실험 (혹은 double cantilever beam, DCB test)을 다양한 작용기로 기능화된 SWNT가 첨가된 탄소섬유복합재 시편에 대하여 수행하였다. 부직포 형태의 탄소나노튜브층을 이용한 시편의 경우 10.6%의 파괴인성 증대를 보였다.

• Journal of Mechanical Science and Technology
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• 제16권12호
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• pp.1652-1663
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• 2002

It is desirable to perform nondestructive evaluation to assess material properties and part homogeneity because manufacturing of carbon/carbon (C/C) composites requires complicated and costly processes. In this work several ultrasonic techniques were applied to carbon/carbon composites for the evaluation of spatial variations in material properties that are attributable to the manufacturing process. In a large carbon/carbon composite manufactured by chemical vapor infiltration (CVI) method, the spatial variation of ultrasonic velocity was measured and found to be consistent with the densification behavior in CVI process in order to increase the density of C/C composites. Ultrasonic velocity and attenuation depend on a density variation of materials. Low frequency through-transmission scans based on both amplitude and time-of-flight of the ultrasonic pulse were used for mapping out the material property inhomogeneity These results were compared with that obtained by dry-coupling ultrasonics. Pulse-echo C-scans was used to image near-surface material property anomalies such as the placement of spacers between disks during CVI. Also, optical micrograph had been examined on the surface of C/C composites using a destructive way.

• Carbon letters
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• 제28권
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• pp.9-15
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• 2018

In the aerospace field, Carbon/Cork composites have been used for rocket propulsion systems as a light weight structural component with a high bending stiffness and high thermal insulation properties. For the fabrication of a carbon composite with a heat insulation cork part, the bonding properties between them are very important to determine the service life of the Carbon/Cork composite structure. In this study, the changes in the interfacial adhesion and mechanical properties of Carbon/Cork composites under accelerated aging conditions were investigated. The accelerated aging experiments were performed with different temperatures and humidity conditions. The properties of the aged Carbon/Cork composites were evaluated mainly with the interfacial strength. Finally, the lifetime prediction of the Carbon/Cork composites was performed with the long-term property data under accelerated conditions.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.597-600
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• 2014

In this work, the electromagnetic interference shielding effectiveness (EMI-SE) of carbon nanotube/carbon fiber-reinforced HDPE matrix composites are investigated with various preparation conditions, such as the carbon fiber and carbon nanotube content, the presence of metal additives, as well as mixing speed and time. It was found that the EMI-SE of the composites increased with filler contents and metal additives. These results indicate that the content and length of carbonaceous fillers determine the electric networks in the composites, resulting in the control of the EMI-SE of the composites.