• Composites Research
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• v.18 no.5
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• pp.34-39
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• 2005

The relationship between strain and applied potential was derived for composite actuators consisting of single-wall carbon nanotubes (SWNTs) and conductive polymers (CPs). During deriving the relationship, an electrochemical ionic approach is utilized to formulate the electromechanical actuation of the composite film actuator. This relationship can give us a direct understanding of the actuation of a nanoactuator. The results show that the well-aligned SWNTs composite actuator can give good actuation responses and high actuating forces available. The actuation is found to be affected by both SWNTs and CPs components and the actuation of SWNTs component has two kinds of influences on that of the CPs component: reinforcement at the positive voltage and abatement at the negative voltage. Optimizations of SWNTs-CPs composite actuator may be achieved by using well-aligned nanotubes as well as choosing suitable electrolyte and input voltage range.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2819-2822
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• 2010

Forest of single-walled carbon nanotubes (SWNTs) was grown at $450^{\circ}C$ by water-plasma chemical vapor deposition using ultrathin iron on alumina supporting film. The growth rate of the SWNT forest is ${\sim}0.9\;{\mu}m/min$, and the diameters of nanotubes are mainly in a range of 3.0 ~ 3.5 nm. The low intensity ratio of D- to G-band ($I_D/I_G$ ~ 0.098) in Raman spectra indicates that our SWNT forest grown at $450^{\circ}C$ is fairly pure and crystalline. This low temperature growth of SWNT forest may enable variable applications requiring the vertically-aligned nanotubes to obtain large surface area.

• Structural Engineering and Mechanics
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• v.67 no.2
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• pp.125-130
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• 2018

This study deals with buckling analysis with stretching effect of functionally graded carbon nanotube-reinforced composite beams resting on an elastic foundation. The single-walled carbon nanotubes (SWCNTs) are aligned and distributed in polymeric matrix with different patterns of reinforcement. The material properties of the CNTRC beams are estimated by using the rule of mixture. The significant feature of this model is that, in addition to including the shear deformation effect and stretching effect it deals with only 4 unknowns without including a shear correction factor. The equilibrium equations have been obtained using the principle of virtual displacements. The mathematical models provided in this paper are numerically validated by comparison with some available results. New results of buckling analyses of CNTRC beams based on the present theory with stretching effect is presented and discussed in details. the effects of different parameters of the beam on the buckling responses of CNTRC beam are discussed.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.293-296
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• 2003

We report on the fabrication and field emission of carbon nanotube field emitters for mass spectrometer. Due to its high aspect ratio and mechanical strength, we use vertically aligned multi-wall carbon nanotubes prepared by thermal chemical vapour deposition as cathodes, Electrons emitted from a CNT are to ionize some sample molecules. We have successfully attained patterned carbon nanotubes grown on two-dimensional 0.7 mm by 0.7 mm Ni square blocks on Si. The emission characteristics show that the field emission initiates at 200 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.131-134
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• 2001

Vertically aligned carbon nanotubes are grown on iron-deposited silicon oxide substrates by thermal chemical vapor deposition of acetylene gas at the temperature range 750∼950$^{\circ}C$. As the growth temperature increases from 750 to 950$^{\circ}C$, the growth rate increases by 4 times and the average diameter also increases from 30 nm to 130 nm while the density increases progresively with the growth temperature and a higher degree of crystalline perfection can be achieved at 950$^{\circ}C$. This result demonstrates that the growth rate, diameter, density, and crystallinity of carbon nanotubes can be controlled with the growth temperature.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1827-1831
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• 2003

Field emission of carbon nanotubes (CNTs) fabricated by disproportionation of CO has been studied. CNTs fabricated on well-ordered Co nanowire arrays formed on the porous anodic aluminum oxide templates were well graphitized, uniform in diameter and aligned vertically with respect to the plane of the template, and showed a good field emission property. Very uniform emissions were observed from the CNTs fabricated at relatively low temperature, $500-600^{\circ}C$. Low fabrication temperature such as $500^{\circ}C$ could make it possible to fabricate CNTs on soda lime glass, a low-cost substrate, for display panel.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.692-693
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• 2002

Well-aligned multi-wall carbon nanotubes (MWNTs) were fabricated by utilizing a radio frequency plasma-enhanced chemical vapor deposition (rf-PECVD) system from Ni particles at the bottom of anodic alumina nanoholes (AAN). To remove the amorphous graphite layers on the AAN surface and to eliminate the protrusion of MWNT tips, the AAN surface with MWNTs were treated by external rf plasma source. As a result, the AAN surface almost became flat without having any protrusion of MWNT tips. The diameter, length of MWNTs and AAN were investigated by using a scanning electron microscopy (SEM). Raman spectroscopy was also used to characterize wall structure of the carbon nanotube. And the emission properties of the MWNTs were measured for the application of field emission display (FED) in near future.

• Carbon letters
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• v.12 no.4
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• pp.207-217
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• 2011

We discuss the influence of few-walled carbon nanotubes (FWCNTs) treated with nitric acid and/or sulfuric acid on field emission characteristics. FWCNTs/tetraethyl orthosilicate (TEOS) thin film field emitters were fabricated by a spray method using FWCNTs/TEOS sol one-component solution onto indium tin oxide (ITO) glass. After thermal curing, they were found tightly adhered to the ITO glass, and after an activation process by a taping method, numerous FWCNTs were aligned preferentially in the vertical direction. Pristine FWCNT/TEOS-based field emitters revealed higher current density, lower turn-on field, and a higher field enhancement factor than the oxidized FWCNTs-based field emitters. However, the unstable dispersion of pristine FWCNT in TEOS/N,N-dimethylformamide solution was not applicable to the field emitter fabrication using a spray method. Although the field emitter of nitric acid-treated FWCNT showed slightly lower field emission characteristics, this could be improved by the introduction of metal nanoparticles or resistive layer coating. Thus, we can conclude that our spray method using nitric acid-treated FWCNT could be useful for fabricating a field emitter and offers several advantages compared to previously reported techniques such as chemical vapor deposition and screen printing.

• Structural Engineering and Mechanics
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• v.78 no.2
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• pp.117-124
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• 2021

This work focused on the novel numerical tool for the bending responses of carbon nanotube reinforced composites (CNTRC) beams. The higher order shear deformation beam theory (HSDT) is used to determine strain-displacement relationships. A new exponential function was introduced into the carbon nanotube (CNT) volume fraction equation to show the effect of the CNT distribution on the CNTRC beams through displacements and stresses. To determine the mechanical properties of CNTRCs, the rule of the mixture was employed by assuming that the single-walled carbon nanotubes (SWCNTs)are aligned and distributed in the matrix. The governing equations were derived by Hamilton's principle, and the mathematical models presented in this work are numerically provided to verify the accuracy of the present theory. The effects of aspect ratio (l/d), CNT volume fraction (Vcnt), and the order of exponent (n) on the displacement and stresses are presented and discussed in detail. Based on the analytical results. It turns out that the increase of the exponent degree (n) makes the X-beam stiffer and the exponential CNTs distribution plays an indispensable role to improve the mechanical properties of the CNTRC beams.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.866-869
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• 2004

A carbon nanotube field emission display(CNT FED) panel with a 2 inch diagonal size was fabricated by using a screen printing of a prepared photo-sensitive CNT paste and vacuum in-line sealing technology. After a surface treatment of the patterned CNT, only the carbon nanotube tips are uniformly exposed on the surface. The diameter of the exposed CNTs are usually about 20nm. The sealing temperature of the panel was around 390 $^{\circ}C$ and the vacuum level was obtained with $1.4{\times}10^{-5}$torr at the sealing. The field emission properties of the diode type CNT FED panel were characterized Now, we are developing a triode type CNT FED with a self-aligned gate-emitter structure.