• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.658-662
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• 2009

In this work, the amine-treated activated carbon nanotubes (A-MWNTs) were used to investigate the $CO_2$ adsorption behaviors. A-MWNTs were prepared by impregnation with amine in methanol after chemical activation methods using a KOH. The characteristics of amine-treated A-MWNTs were studied by X-ray photoelectron spectroscopy (XPS), $N_2$ adsorption, desorption isotherms at 77 K. The specific surface area and pore volume of the A-MWNTs were analyzed by BET equation, BJH method, and t-plot method. $CO_2$ capture capacity as a function of temperature was measured by temperature programmed desorption (TPD). From the results, the amine treatment increased the basicity and nitrogen content of the A-MWNTs. The $CO_2$ adsorption capacity of the amine-nontreated A-MWNTs showed the highest value at room temperature and then greatly decreased with increasing the temperature. However, the amine-treated A-MWNTs presented a softer slope with temperature compared to the amine-nontreated ones. It was due to the strong interactions between $CO_2$ and amino groups presented on the carbon surfaces studied.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.80-83
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• 2005

In this work, effects of oxygen plasma on surface characteristics of carbon fibers were investigated in mechanical properties interfacial of carbon fibers-reinforced composites. The surface properties of the carbon fibers were determined by acid/base values, FT-IR, and X-ray photoelectron spectroscopy (XPS). Also, the mechanical properties of the composites were studied in and critical stress intensity factor ($K_{IC}$) and critical strain energy release rate mode II ($G_{IIC}$) measurements. As experimental results, the $O_{lS}/C_{lS}$ ratio of the carbon fiber surfaces treated by oxygen plasma was increased compared to that of untreated ones, possibly due to development of oxygen-containing functional groups. The mechanical properties of the composites, including $K_{IC}$ and $G_{IIC}$ had been improved in the oxygen plasma on fibers. These results could be explained that the oxygen plasma was resulted in the increase of the adhesion of between fibers and matrix in a composite system.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.23-26
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• 2005

In this work, effects of oxygen plasma on surfc1ce characteristics of carbon fibers were investigated in impact strength of carbon fibers-reinforced composites. The surface properties of the carbon fibers were determined by acid/base values, FT-IR, and X-ray photoelectron spectroscopy (XPS). Also, the mechanical properties of the composites were studied by impact strength measurements. As experimental results, the $O_{IS}/C_{IS}$ ratio of the carbon fiber surfaces treated by oxygen plasma was increased compared to that of untreated ones, possibly due to development of oxygen-containing functional groups. The mechanical properties of the composites, including impact strength had been improved by the oxygen plasma on fibers. These results could be explained that the oxygen plasma resulted in the increase of the adhesion of between fibers and matrix in a composite system.

• Journal of the Korean institute of surface engineering
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• v.41 no.2
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• pp.63-68
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• 2008

Traditionally and generally used calcined clay was carburized, and its characteristics were studied. Carburization treatment was performed by the thermally decomposed carbon and the deposit carbon which occur in a so called 'Boudouard reaction $(2CO{\rightarrow}CO_2+C)'$ at fuel combustion process in a closed-type furnace. The color of the carburized calcine clay changed from yellow to black, and the carbon component revealed as crystalline graphite by the X-ray diffraction test. The weight of the carburized calcine clay decreased to about 4 wt.% by the 1st heating to $1400^{\circ}C$ in air but it does not decreased by the 2nd heating of the same conditions. By the carburization treatment, the water absorption changed from 13 wt.% to 6 wt.%, and the contact angle for water drop changed, too, from 0 to $87^{\circ}$ which was tested by the photograph of one minute after a water drop contact. It means the carburized calcine clay does not absorb water drop so it has a hydrophobic characteristic.

• Journal of the Korean Ceramic Society
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• v.30 no.7
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• pp.557-562
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• 1993

Following conclusions are made from the detalied research on the relation between the phase change of the petroleum raw cokes after ball milling and the preheat treatment temperature. The petroleum raw cokes species are preheated in the temperature range of 350~45$0^{\circ}C$. At the preheat treatment temperature of 40$0^{\circ}C$ the particles of petroleum raw cokes from ball milling become spheically shape with the almost uniform particle size distribution of 1~5${\mu}{\textrm}{m}$. At the same temperature, they became low-graphitized with the d0.02 X-ray diffraction index of 3.41$\AA$. The carbon material made from the petroleum raw cokes at 40$0^{\circ}C$ turned out to have the good modulus of rupture about 600kg/$\textrm{cm}^2$, with the bulk density around 1.8g/㎤ and the appearent porosity around 8%.

• Carbon letters
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• v.12 no.2
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• pp.112-115
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• 2011

The scope of this work investigates the relationship between the amount of oxygen-functional groups and hydrogen adsorption capacity with different concentrations of phosphoric acid. The amount of oxygen-functional groups of activated carbons (ACs) is characterized by X-ray photoelectron spectroscopy. The effects of chemical treatments on the pore structures of ACs are investigated by $N_2$/77 K adsorption isotherms. The hydrogen adsorption capacity is measured by $H_2$ isothermal adsorption at 298 K and 100 bar. In the results, the specific surface area and pore volume slightly decreased with the chemical treatments due to the pore collapsing behaviors, but the hydrogen storage capacity was increased by the oxygen-functional group characteristics of AC surfaces, resulting from enhanced electron acceptor-donor interaction at interfaces.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.402-410
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• 2008

Single-walled carbon nanotubes (SWCNTs) were currently produced together with some contaminants such as a metallic catalyst, amorphous carbon, and graphitic nanoparticles, which should be sometimes purified for their applications. This study aimed to develop efficient, scalable purification processes but less harmful to SWCNTs. We designed three-step purification processes: acidic treatment, surface functionalization and soxhlet extraction, and heat treatment. During the soxhlet extraction using tetrahydrofuran, specifically, carbon impurities could be easily expelled through a glass thimble filter without any significant loss of CNTs. Finally, SWCNTs were left as a bulky paper on the filter through membrane filtration. Vertically aligned SWCNTs on one side of bulky paper were well developed in a speparation from the filter paper, which were formed by being sucked through the filter pores during the pressurized filtration. The bucky paper showed a very high peak current density of field emission up to $200\;mA/cm^2$ and uniform field emission images on phosphor, which seems very promising to be applied to vacuum microelectronics such as microwave power amplifiers and x-ray sources.

• Journal of Powder Materials
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• v.20 no.1
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• pp.53-59
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• 2013

Fe-TiC composite powder was fabricated via two steps. The first step was a high-energy milling of FeO and carbon powders followed by heat treatment for reduction to obtain a (Fe+C) powder mixture. The optimal condition for high-energy milling was 500 rpm for 1h, which had been determined by a series of preliminary experiment. Reduction heat-treatment was carried out at $900^{\circ}C$ for 1h in flowing argon gas atmosphere. Reduced powder mixture was investigated by X-ray Diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM) and Laser Particle Size Analyser (LPSA). The second step was a high-energy milling of (Fe+C) powder mixture and additional $TiH_2$ powder, and subsequent in-situ synthesis of TiC particulate in Fe matrix through a reaction of carbon and Ti. High-energy milling was carried out at 500 rpm for 1 h. Heat treatment for reaction synthesis was carried out at $1000{\sim}1200^{\circ}C$ for 1 h in flowing argon gas atmosphere. X-ray diffraction (XRD) results of the fabricated Fe-TiC composite powder showed that only TiC and Fe phases exist. Results from FE-SEM observation and Energy-Dispersive X-ray Spectros-copy (EDS) revealed that TiC phase exists uniformly dispersed in the Fe matrix in a form of particulate with a size of submicron.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.479-485
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• 2011

Pt-Bi/C catalysts supported on carbon black with various Pt/Bi ratios were synthesized by a reduction method. Chloroplatinic acid hydrate ($H_2PtCl_6{\cdot}xH_2O$) and bismuth (III) nitrate pentahydrate ($Bi(NO_3)_3{\cdot}5H_2O$) were used as precursors for Pt and Bi, respectively. Before loading metal on carbon, heat treatment and pretreatment of carbon black in an acidic solution was conducted to enhance the degree of dispersion. The physical property of the synthesized catalysts was investigated by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern of untreated Pt-Bi/C catalyst showed BiPt and $Bi_2Pt$ peaks in addition to Pt peaks. These results imply that Bi atoms were incorporated into the Pt crystal lattice by Pt-Bi alloy formation. The catalytic activity for methanol oxidation was measured using cyclic voltammetry in a mixture of 0.5 M $H_2SO_4$ and 0.5 M $CH_3OH$ aqueous solution. The addition of proper amount of Bi was found to significantly improve catalytic activity for methanol oxidation. The catalytic activity for methanol oxidation was closely related to the stability between electrode and electrolyte. In order to investigate the stability of catalysts, chronoamperometry analysis was carried out in the same solution at 0.6 V.

• Carbon letters
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• v.12 no.4
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• pp.229-235
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• 2011

Isotactic polyacrylonitrile (PAN) with triad isotacticity of 0.53, which was determined by $^{13}C$ NMR, using dialkylmagnesium as an initiator, was successfully synthesized. Isothermal treatment of iso-PAN was conducted in air at 200, 220, 250 and $280^{\circ}C$. Structural evolutions and chemical changes were studied with Fourier transformation infrared and wide-angle X-ray diffraction during stabilization. A new parameter $CNF={I_{2240cm}}^{-1}/ ({I_{1595cm}}^{-1}+f^*{I_{1595cm}}^{-1})$ was defined to evaluate residual nitrile groups. Crystallinity and crystal size were calculated with X-ray diffraction dates. The results indicated that the nitrile groups had partly converted into a ladder structure as stabilization proceeded. The rate of reaction increased with treatment temperature; crystallinity and crystal size decreased proportionally to pyrolysis temperature. The iso-conversional method coupled with the Kissinger and Flynn-Wall-Ozawa methods were used to determine kinetic parameters via differential scanning calorimetry analysis with different heating rates. The active energy of the reaction was 171.1 and 169.1 kJ/mol, calculated with the two methods respectively and implied the sensitivity of the reaction with temperature.