• Journal of Powder Materials
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• v.21 no.1
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• pp.50-54
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• 2014

A powder-in-sheath rolling method was applied to a fabrication of a carbon nano tube (CNT) reinforced aluminum composite. A STS304 tube with an outer diameter of 34 mm and a wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol was filled in the tube by tap filling and then processed to 73.5% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the powder-in-sheath rolling decreased slightly with increasing of CNTs content, but exhibited high value more than 98. The grain size of the aluminum matrix was largely decreased with addition of CNTs; it decreased from $24{\mu}m$ to $0.9{\mu}m$ by the addition of only 1 volCNT. The average hardness of the composites increased by approximately 3 times with the addition of CNTs, comparing to that of unreinforced pure aluminum. It is concluded that the powder-in-sheath rolling method is an effective process for fabrication of CNT reinforced Al matrix composites.

• Fibers and Polymers
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• v.7 no.1
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• pp.85-87
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• 2006

The tensile-recoil compressional behavior of the carbon nanotube reinforced mesophase pitch (MP)-based composite carbon fibers (CNT-re-MP CFs) was investigated by using Instron and SEM. The CNT-re-MP CFs exhibited improved, or at least equivalent, compressive strength as compared with commercial MP-based carbon fibers. Particularly, when CNT of 0.1 wt% was reinforced, the ratios of recoil compressive strengths to tensile strength of CNT-re-MPCFs were much higher (the difference is at least 10 % or higher) than those for the commercial counterparts and even than those for PAN-based commercial carbon fibers. FESEM micrographs showed somewhat different fractography from that of a typical shear failure as the CNT content increased.

• Korean Journal of Materials Research
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• v.30 no.3
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• pp.149-154
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• 2020

A powder-in-sheath rolling method is applied to the fabrication of a carbon nano tube (CNT) reinforced copper composite. A copper tube with outer diameter of 30 mm and wall thickness of 2 mm is used as sheath material. A mixture of pure copper powder and CNTs with a volume content of 3 % is filled in a tube by tap filling and then processed to an 93.3 % reduction using multi-pass rolling after heating for 0.5 h at 400 ℃. The specimen is then sintered for 1h at 500 ℃. The relative density of the 3 vol%CNT/Cu composite fabricated using powder in sheath rolling is 98 %, while that of the Cu powder compact is 99 %. The microstructure is somewhat heterogeneous in width direction in the composite, but is relatively homogeneous in the Cu powder compact. The hardness distribution is also ununiform in the width direction for the composite. The average hardness of the composites is higher by 8Hv than that of Cu powder compact. The tensile strength of the composite is 280 MPa, which is 20 MPa higher than that of the Cu powder compact. It is concluded that the powder in sheath rolling method is an effective process for fabrication of sound CNT reinforced Cu matrix composites.

• Korean Journal of Materials Research
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• v.18 no.11
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• pp.583-591
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• 2008

In this study, two series of CNT/$TiO_2$ electrodes were prepared. The decrease of surface area compared with that of the pristine carbon nanotubes (CNTs) indicated the blocking of micropores on the surface of the CNTs; was further supported by scanning electron microscopy (SEM) and field emission SEM (FE-SEM) observations. The X-ray diffraction (XRD) results showed that the CNT/$TiO_2$ composites contained a mix of anatase and rutile forms of $TiO_2$ particles when the precursor was $TiO_2$ powder, whereas when the precursor was Ti ($OC_4H_7$) (TNB), the composites contained only the typical single and clear anatase $TiO_2$ particles. The energy dispersive X-ray spectroscopy (EDX) spectra showed the presence of C, O and Ti peaks for all samples. It was found that catalytic decomposition of methylene blue (MB) solution could be attributed to synthetic effects between the $TiO_2$ photocatalysis and electro-assisted CNTs network, and that photoelectrocatalytic oxidation increased with an increase of CNT composition. It was also found that the photoelectrocatalytic oxidation efficiency for MB is higher than that of photocatalytic oxidation. Moreover, the CNT/$TiO_2$ composites catalyst prepared by the impregnation method demonstrates higher photoelectrocatalytic activity than the mechanical mixture with the same CNT content.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.156-157
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• 2006

To improve mean-life and reliability of power cable in this study, we have investigated chemical properties showing by changing the content of Carbon nanotube(CNT) that is semiconductive additives for underground power transmission. Specimens were made of sheet form with the three of existing resins and the five of specimens for measurement. Chemical properties of specimens was measured by FT-ATR (Fourier Transform Attenuated Total Reflectance). The condition of specimens was a solid sheet. We could observe functional group (C=O, carbonyl group) of specimens through FT-ATR. From these experimental result, the concentration of functional group (C=O) was high according to increasing the content of Carbon nanotube. We could know CNT/EEA was excellent more than other specimens from above experimental results.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.570-575
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• 2006

In this paper, we have investigated thermal properties by changing the content of carbon nanotube, which is component part of semiconductive shield in underground power transmission cable. Heat capacity (${\Delta}H$), glass transition temperature (Tg) and melting temperature (Tm) were measured with the samples of eight, through DSC (Differential Scanning Calorimetry), and the measurement ranges of temperature selected from $-100[^{\circ}C]\;to\;100[^{\circ}C]$ with heating temperature selected per $4[^{\circ}C/min]$ Also, high temperature, heat degradation initiation temperature, and heat weight loss were measured by TGA (Thermogravimetric Analysis) in the temperature from $0[^{\circ}C]\;to\;700[^{\circ}C]$ with rising temperature of $10[^{\circ}C/min]$. As a result, the Glass transition temperatures of the sample were showed near $-20[^{\circ}C]{\sim}25[^{\circ}C]$, and the heat capacity and melting temperature from the DSC was increased according to increasing the content of carbon nanotube, while, thermal diffusivity was increased according to increasing the content of carbon nanotube. Also, heat degradation initiation temperature from the TGA results was increasing according to increasing the content of carbon nanotube with CNT/EEA. Therefore, heat stabilities of EVA, which contained the we VA (vinyl acetate), showed the lowest.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.161-167
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• 2008

Multi-walled carbon nanotubes (MWCNT)-reinforced poly(ethylene-co-ethyl acrylate) (EEA) nanocomposites were prepared by both melt and solution mixing methods. The mechanical, thermal, and electrical properties were investigated as a function of type and loading of CNT. The tensile strength and modulus increased, while elongation at break decreased with increasing MWCNT content. The hollow-type MWCNT showed an improved tensile strength and elongation at break compared with a conventional MWCNT. The thermal degradation temperature was increased by around $40^{\circ}C$ with increasing the amount of MWCNT. The melt-mixed composites showed the highest volume resistivity. In the case of solution-mixed composites, the conventional MWCNT was estimated to show much lower volume resistivity than that of hollow MWCNT. The number and length of extruded CNT onto the fractured surface increased by both increasing the content of CNT and employing the tensile strain to the sample. The melt-mixed specimens showed much smaller number and shorter length of extruded CNT.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.29-37
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• 2013

PURPOSES : This study aims to review the possibility of developing a road snow-melting system that can prevent slip accidents by maintaining a constant temperature of the winter roads and enhance performance of structures, including improvement of compressive strength by mixing carbon nanotube (hereafter referred to as CNT) with cement paste, the basic material. METHODS : To achieve the above purpose, an experiment was conducted by mixing power-type CNT and wrap-type CNT up to cement paste formulation by weight of 0.0wt%~4.1wt% in accordance with "KS L ISO 679(of cement strength test method)", and compressive strength was measured at 28 days of curing. In addition, the volume resistivity of the specimen was measured to test thermal and electrical characteristics, and the rate of temperature changes in specimen surface by power consumption was measured by passing electricity through the cross-sections of the specimen. Meanwhile, the criteria for checking the performance as a road snow-melting system was determined as volume resistivity of $100{\Omega}{\cdot}cm$ or less. RESULTS : A comparative analysis between specimen with 0wt% CNT content in plain status and specimen containing various types of CNTs was carried out. From its results, it was found that compressive strength increased approximately 19%, showing the highest rate when 0.2wt% of wrap-type CNT was contained, but volume resistivity of $100{\Omega}{\cdot}cm$ or less appeared only in specimens containing more than 0.2wt% CNT. In addition, it was observed that the surface temperature increased by $4.62^{\circ}C$ per minute on average in specimens containing 3.2wt% CNT. CONCLUSIONS : In this study, CNT was examined as an underlying material for a road snow-melting system, and the possibility of developing the road now-melting system was reviewed by conducting various experiments using CNT-Cement composites. From the experimental results, the specimens were found to have a superior performance when compared to the existing road snow-melting systems that place the heat transfer medium such as copper on the road. However, satisfactory strength performance were not obtained from the specimen containing CNT(2.0% or more) that functions as a heating element, which leads to the need for reviewing methods to increase the strength by using plasticizer or admixture.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.218-219
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• 2007

This paper researched permittivity of carbon nanotube reinforced semiconductive shield materials for power cable in accordance with carbon nanotube content. Permittivity measured 1[Hz], 1[kHz], 1[Mhz] in frequency range, and range of temperature measured to 100$[^{\circ}C]$ from -50$[^{\circ}C]$. It is stable to 100$[^{\circ}C]$ from -50$[^{\circ}C]$ without different gap. But, in case of CNT:CB=100:0, permittivity decreased by temperature increment. Also, in case of CNT:CB=100:0, it shows highest permittivity. Permittivity of change have little no the power of influence by frequency, but in case of 1[Mhz], CNT:CB=100:0 of specimen decreased more than other frequency. This influence thinks phenomenon of induced electricity dispersion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.2
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• pp.153-160
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• 2013

An orthotropic magneto-rheological rubber composite (MRRC) based on a general-purpose rubber can be manufactured by using an electromagnetic device during the curing processes of rubber mixtures. The magnetic transmissivity of MRRCs increases with the iron particle (IP) content, and that of aligned MRRCs with a 2-T magnetic field is 1.8 to 2 times higher as compared to that of randomly dispersed MRRCs. The effect of a 2-T magnetic field on carbon nanotube (CNT) reinforced MRRC has been identified clearly, and the magnetic transmissivity is found to be 3.7%. The compressive stress of MRRC (IP 90 + CNT 5, 2 T alignment) under a magnetic field of 0.49 T is 2.1 times higher as compared to that of the matrix. The MR effect of MRRC increases with the IP content, and that of aligned MRRC with the IP 90 and 2 T magnetic field is 20.4%. It is confirmed that the magnetic field when making the specimen and when performing the compression test greatly impacts the compression characteristics.