• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1136-1139
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• 2005

As alternative materials for bipolar plate of PEM Fuel Cells, carbon composites were fabricated by compression molding. In this study, four types of nano particles, such as Carbon nanotubes, Carbon black, GX-15 and P-15 were mixed with epoxy resin to provide electric conductivity and structural properties. By increasing pressure during molding and volume ratio of nano particles, the physical contact among particles was improved resulting in increased electric conductivity. Surface resistance test showed, P-15 particles have the highest electric conductivity.

• Carbon letters
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• v.10 no.4
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• pp.320-324
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• 2009

We investigated the effect of diameter and content of carbon nanotubes (CNTs) on the physical properties of styrenebutadiene rubber (SBR)/CNTs nanocomposites. CNTs-reinforced SBR nanocomposites were prepared by the melt mixing process. CNTs with different diameters were synthesized by the chemical vapor deposition method (CVD). In this work, the mechanical property and other physical properties of SBR/CNTS nanocomposites were discussed as a function of the content and diameter of CNTs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.285-286
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• 2008

Recently, epoxy based nano-composites are being increasingly investigated for their electrical properties, since the introduction of nano fillers demonstrate several advantages in their properties when compared with the similar properties obtained for epoxy systems with micrometer sized fillers. We calculated scale and shape parameter using dielectric strength. In this paper, it is investigated that the allowable' breakdown probability of specimens is stable at some value using Weibull statistics. Therefore we found that breakdown probability of specimens is stable until 20 [%].

• Proceedings of the Korean Magnestics Society Conference
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• 2006.11a
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• pp.30-31
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• 2006

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.158-161
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• 2006

SiC materials have been extensively studied for high temperature components in advanced energy conversion system and advanced gas turbine. However, the brittle characteristics of SiC such as law fracture toughness and law strain-to fracture impose a severe limitation on the practical applications of SiC materials. SiC/SiC composites can be considered as a promising candidate in various structural materials, because of their good fracture toughness. In this composite system, the direction of SiC fiber will give an effect to the mechanical properties. It is therefore important to control a properdirection of SiC fiber for the fabrication of high performance SiC/SiC composites. In this study, unidirection and two dimension woven structures of SiC/SiC composites were prepared starting from Tyranno SA fiber. SiC matrix was obtained by nano-powder infiltration and transient eutectoid (NITE) process. Effect of microstructure and density on the sintering temperature in NITE-SiC/SiC composites are described and discussed with the fiber direction of unidirection and two dimension woven structures.

• Journal of Power System Engineering
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• v.14 no.6
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• pp.83-88
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• 2010

The wear behavior of epoxy matrix composites filled with nano sized silica particles is discussed in this paper. Especially, the variation of the coefficient of friction and the wear resistance according to the change of apply load and sliding velocity were investigated for these materials. Wear tests of pin-on-disc mode were carried out and the wear test results exhibited as following ; The epoxy matrix composites showed lower coefficient of friction compared to the neat epoxy through the whole sliding distance. As increasing the sliding velocity the epoxy matrix composites indicated lower coefficient of friction, whereas the neat epoxy showed higher coefficient of friction as increasing the sliding velocity. The specific friction work of both materials were increased with apply load. In case of the epoxy matrix composites, the running in periods of friction were reduced as increase in apply load. The epoxy matrix composites were improved the wear resistance by adding the nano silica particles remarkably. It is expected that the load carrying capacity of the epoxy matrix composites will be improved by increase of Pv factor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.4
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• pp.348-351
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• 2007

Recently, Nanotechnology becomes a major issue in most part of industries. Nanotechnology is expected to develop various application products due to nano material mired composites is improved physical and electrical properties compared to conventional composites materials. Dielectric and insulation materials need to develop and improve like other field about nanotechnology. In this paper, we reported dielectric dispersion by size(no filler, $1.2{\mu}m$, 500 nm, 10 nm), frequencies(60, 120, 1 kHz), and temperatures($30{\sim}170^{\circ}C$). Dielectric constant of composites materials with filler shows higher than composites materials without filler and increased depending on rising temperatures in low frequency region. It was the effect that nano-filler and impurities in composites contributed to electrical conductivity. And dielectric properties depending on temperatures shows to change in low frequency region dramatically We analyzed interfacial polarization in low frequency region($10^{-2}$ Hz) and oriented polarization in high frequency region($10^{-5{\sim}6}$ Hz) on composites materials.

• Nano
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• v.13 no.11
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• pp.1850133.1-1850133.9
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• 2018

The hexagonal boron nitride nanosheets (BN) were firstly treated by silane coupling agents 3-aminopropyltriethoxysilane (KH550) and 3-glycidoxypropyl-trimethoxysilane (KH560) to introduce some amino and epoxy (EP) groups on the BN surface. These modified BN nanosheets were incorporated into an EP matrix to prepare BN@KH560/EP composites with excellent thermal conductivity and electrical insulation properties. Results showed that the thermal conductivity of BN@KH560/EP composite with 20 vol% BN dosage was found to be 0.442 W/($m{\cdot}K$), which was 81% higher than that of pure EP resin. Both BN/EP composites treated by KH550 and KH560 showed rather good electrical insulation properties, although the dielectric constant of BN@KH550/EP composites were slightly higher than BN@KH560/EP composites. Moreover, BN@KH560/EP composites also showed better thermal and mechanical properties than that of BN@KH550/EP composites.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.214-218
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• 2013

Nylon66/multi-walled carbon nano tube (MWCNT) composites were fabricated by twin screw extruder. The contents of MWCNT were 1, 3, 5, and 7 wt%. Thermal properties, dispersion, rheological and impact properties were measured by DSC, TGA, X-ray diffraction (XRD), SEM, Dynamic rheometer, and Izod impact tester. The effect of MWCNT on the non-isothermal crystallization of Nylon66 was confirmed by DSC. The complex viscosity at low frequency and the shear thinning tendency of the composites increased with MWCNT content. An increase in the elasticity was confirmed from the decrease in the slop of G'-G" plot. Izod impact strengths of the composites were analyzed as a measure of mechanical properties, which indicated that the composites exhibit a 60% enhancement for the impact strength when 3 wt% MWCNT was added. The dispersion of MWCNT within Nylon66/MWCNT composites was also checked by SEM.

• Composites Research
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• v.29 no.6
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• pp.353-357
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• 2016

An appropriate way to fabricate a hybrid composite containing evenly dispersed carbon nano tubes(CNTs) is to stacking B-stage resin films that contain evenly dispersed CNTs and various reinforcing fiber layers alternatively. In the present study, B-stage resin films are manufactured via shear mixing and three-roll milling. CNT dispersion in resin via these two processes are evaluated by SEM on their fracture surfaces. For more efficient process, the dispersivities are evaluated according to the number of calendering passes. Samples are made for different number of passes during calendering, and their dispersions are evaluated via SEM fractographs as well as by measuring their electrical conductivities. Additionally, the optimal process conditions are obtained by measuring the electrical conductivity and evaluating their dispersivity of the samples prepared by gap mode and force mode.