• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1150-1153
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• 2008

The coupled oscillation of multi-walled carbon-nanotube (MWCNT) oscillators consisting of (5n, 5n) CNTs was investigated by molecular dynamics simulations. The results show that the inter-wall coupling leads to frequency splits. And there are consistently three primary frequency peaks for the quadric-walled, penta-walled and hexa-walled CNT oscillators. It is independent of the wall parameters, suggesting applications as triple-frequency generators. Furthermore, at least one of the primary frequencies of a MWCNT oscillator is lower than that of its double-walled counterpart.

• Carbon letters
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• v.24
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• pp.41-46
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• 2017

The microstructure, flexural properties, electrical conductivity, thermal conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) of epoxy composites filled with multi-walled carbon nanotubes (CNTs), exfoliated graphite nanoplatelets (xGnPs) and CNT-xGnP hybrid filler were investigated. The EMI SE of the CNT-xGnP hybrid composite was higher than 25 dB at 100 MHz while that of the xGnP based composite was almost zero. The flexural modulus of the CNT-xGnP based epoxy composite continuously increased to 3.32 GPa with combined filler content up to 10 wt% while that of the CNT based epoxy composites slightly decreased to 1.96 GPa at 4 wt% CNT, and dropped to 1.57 GPa at 5 wt% loading, which is lower than that of epoxy. The CNT and CNT-xGnP samples had the same EMI SE at the same surface resistivity, because samples with the same surface conductivity have the same amount of the charge carriers.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.898-902
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• 2008

Prepared are three types of composite supercapacitor electrode, such as electroactive polyaniline(PAN), PAN/multi-walled carbon nanotube(CNT), and $CNT/PAN/RuO_2$. Cyclic voltammetry was performed to investigate the supercapacitive properties of these electrodes in an electrolyte solution of 1.0M $H_2SO_4$. The $CNT/PAN/RuO_2$ electrode showed the highest specific capacitance at all scan rates(e.g., 441 and $392F\;g^{-1}$ at 100 and $1,000mV\;s^{-1}$, respectively). In cycle performance, however, the PAN/CNT electrode demonstrated the best capacitance retention (66%) at $10^4th$ cycle.

• Journal of the Korean Ceramic Society
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• v.45 no.10
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• pp.610-617
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• 2008

Multi-walled carbon nanotube(CNT) reinforced hydroxyapatite composite coating with a thickness of $5{\mu}m$ has been successfully deposited on Ti substrate using aerosol deposition(AD). The coating had a dense microstructure with no cracks or pores, showing good adhesion with the Ti substrate. Microstructural observation using field-emission scanning electron microscopy(FE-SEM) and transmission electron microscopy(TEM) showed that CNTs with original tubular morphology were found in the hydroxyapatite-CNT(HA-CNT) composite coating. Measurements of hardness and elastic modulus for the coating were performed by nanoindentation tests, indicating that the mechanical properties of the coating were remarkably improved by the addition of CNT to HA coating. Therefore, HA-CNT composite coating produced by AD is expected to be potentially applied to the coating for high load bearing implants.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.200-203
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• 2007

Carbon nanotubes (CNTs) have attracted an increasing attention due to their superior mechanical properties and potential application in industries. The strength of CNT has been predicted or calculated through several simulation techniques but actual experiments on stress-strain behavior are rare due to its dimensional limit, nanoscale positioning/manipulation, and instrumental resolution. We have attempted to observe straining responses of a multi-walled carbon nanotube (MWNT) with different growth methods by performing an in-situ tensile testing in a scanning electron microscope. Linear deformation and fracture behaviors of MWNT were successfully observed and its force-displacement curve was also measured from the bending stiffness and displacement of the force sensor and manipulator. We also obtained different tensile load of carbon nanotube with different growth methods.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.83-86
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• 2004

Carbon nanotube (CNT) tips in tapping mode atomic force microscopy (AFM) enable very high-resolution imaging, measurements, and manipulation at the nanoscale. We present recent results based on experimental analysis that yield new insights into the dynamics of CNT probe tips in tapping mode AFM. Experimental measurements are presented of the frequency response and dynamic amplitude-distance data of a high-aspect-ratio multi-walled (MW) CNT tip to demonstrate the non-linear features including tip amplitude saturation preceding the dynamic buckling of the MWCNT. Surface scanning is performed using a MWCNT tip on a SiO$_2$ grating to verify the imaging instabilities associated with MWCNT buckling when used with normal control schemes in the tapping mode. Lastly, the choice of optimal setpoints for tapping mode control using CNT probe tip are discussed using the experimental results.

• Korean Journal of Materials Research
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• v.14 no.11
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• pp.807-812
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• 2004

The uniformity of emission mage and field emission properties of carbon nanotube(CNT) cathodes dependence on CNT particle dispersion were investigated for field emission displays. We used multi-walled carbon nanotubes (MWNTs) synthesized by CVD method as the field emitter materials. CNT dispersion in CNT ink was carried out by ultrasonication and shaking methods. According to CNT dispersion conditions, the uniformity of emission image and field emission properties of CNT cathodes were greatly affected. The smaller particles of filler materials and CNT powders provide the better properties of the CNT cathodes.

• Korean Journal of Materials Research
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• v.16 no.9
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• pp.550-556
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• 2006

Photosensitive carbon nanotube (CNT) pastes are explored to develop a CNT field emitter for field emission display (FED) application. We formulated a photosensitive paste including multi-walled CNTs (MWNTs) for screen printing. The photosensitive CNT paste was synthesized by mixing of MWNTs, inorganic fillers (nano metal), organic vehicle, monomers and photo initiator. The CNT paste films were patterned by using backside exposure technique. The CNTs were strongly fixed on a cathode by formation of carbon residue during firing process. For the CNT emitters, current-voltage(I-V) characteristics and images of field emission were evaluated. The emission properties of CNT emitters are dependent on the paste composition. A turn-on electric field for the CNT field emitters is measured to be 1 V/$\mu$m. Additionally, the effect of heat treatment parameter on field emission properties was discussed. The newly formulated photosensitive CNT paste can be potentially applicable to highly reliable CNT field emitters.

• Journal of Sensor Science and Technology
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• v.22 no.5
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• pp.315-320
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• 2013

In this paper, the properties of strain sensors made of spin-capable multi-walled carbon nanotubes (MWCNTs) were characterized and their sensing mechanisms analyzed. The key contribution of this paper is a new fabrication technique that introduces a simpler transfer method compared to spin-coating or dispersion CNT. Resistance of the MWCNT sheet strain sensor increased linearly with higher strain. To investigate the effect of CNT concentration on sensitivity, two strain sensors with different layer numbers of MWCNT sheets (one and three layers) were fabricated. According to the results, the sensor with a three-layer sheet showed higher sensitivity than that with one layer. In addition, experiments were conducted to examine the effects of environmental factors, temperature, and gas on sensor sensitivity. An increase in temperature resulted in a reduction in sensor sensitivity. It was also observed that ambient gas influenced the properties of the MWCNT sheet due to charge transfer. Experimental results showed that there was a linear change in resistance in response to strain, and the resistance of the sensor fully recovered to its unstressed state and exhibited stable electromechanical properties.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.997-1000
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• 2004

This paper introduces our basic research about a carbon nanotube(CNT) sample for the fabrication of nanotweezer. We have made the nanotweezer through the physical adhesion of multi-walled carbon nanotubes(MWCNTs) on two sharp tungsten tips. Thereby we needed the CNT sample which is proper to this fabrication process. And we applied the dielectrophoretic methods to the fabrication of the CNT sample. During the basic experiment, we used a sharp edged electrode and a flat electrode as electrodes for dielectrophoresis and just a function generator as a voltage source for the generation of electric field.