• Carbon letters
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• 제18권
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• pp.56-61
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• 2016

Cellulose fibers were stabilized by treatment with an electron-beam (E-beam). The properties of the stabilized fibers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The E-beam-stabilized cellulose fibers were carbonized in N₂ gas at 800℃ for 1 h, and their carbonization yields were measured. The structure of the cellulose fibers was determined to have changed to hemicellulose and cross-linked cellulose as a result of the E-beam stabilization. The hemicellulose decreased the initial decomposition temperature, and the cross-linked bonds increased the carbonization yield of the cellulose fibers. Increasing the absorbed E-beam dose to 1500 kGy increased the carbonization yield of the cellulose-based carbon fiber by 27.5% upon exposure compared to untreated cellulose fibers.

• 공업화학
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• 제1권2호
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• pp.176-181
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• 1990

탄소섬유/알루미늄 복합 재료의 계면 전단 강도를 향상시키기 위하여 탄소섬유 표면을 $400-600^{\circ}C$의 온도 범위에서 황화수소 기체로 처리하였다. 처리 탄소섬유 표면의 변화를 주사 전자 현미경과 X-선 광전자 스펙트럼에 의해 관찰하고 분석하여 표면 처리 탄소섬유의 표면에 황 화합물이 존재하는 것을 확인하고, 표면처리 탄소섬유의 탄소 및 탄소의 함량 변화를 조사하였다. 탄소섬유 표면의 황화수소 기체 처리의 최적 온도는 $550^{\circ}C$였고, 처리 탄소섬유 표면의 황 화합물은 disulfide, $(S)_n$ 및 thiophene의 형태를 이루고 있었다. 처리 탄소섬유는 처리 온도 $400-600^{\circ}C$의 범위에서 5% 정도의 인장 강도 저하를 나타냈다.

• 대한기계학회논문집B
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• 제40권11호
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• pp.697-704
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• 2016

본 논문에서는 역청탄인 Glencore 탄을 염산과 질산수용액을 이용하여 산 처리하고 원탄과 산 처리 된 석탄의 물리, 화학적 비교분석과 직접탄소 이용 연료전지(Direct Carbon Fuel Cell, DCFC)의 성능 비교 분석을 수행하였다. 석탄의 물성들을 분석하기 위해 열중량 분석과 가스 흡착법, X선 광전자 분광법을 수행하였다. 열중량 분석을 통해 연료의 열적 반응성이 증가하였음을 알 수 있었고, 가스 흡착법 결과로 기공의 평균지름은 변화가 없었지만 표면적은 감소함을 알 수 있었다. X선 광전자 분광법에서는 $HNO_3$ 처리의 경우 가장 높은 산소/탄소 비율을 보였고, 이를 통해 다양한 표면 산소작용기가 증가한 것을 확인하였다. 연료의 표면 물성과 전기화학 성능을 비교한 결과, 표면의 산소 성분의 변화가 DCFC의 성능 향상에 가장 큰 영향을 미침을 알 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.586-591
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• 2001

This research investigated the feasibility of the accelerated carbonation of cement waste forms with carbon dioxide in a supercritical state. Hydraulic cement has been used as a main solidification matrix for the immobilization of radioactive and/or hazardous wastes. As a result of the hydration reaction for major compounds of portland cement, portlandite (Ca(OH)$_2$) is present in the hydrated cement waste form. The chemical durability of a cement form is expected to increase by converting portlandite to the less soluble calcite (CaCO$_3$). For a faster reaction of portlandite with carbon dioxide, SCCD (supercritical carbon dioxide) rather than gaseous $CO_2$, in ambient pressure is used. The cement forms fabricated with an addition of slated lime or Na-bentonite were cured under ambient conditions for 28days and then treated with SCCD in an autoclave maintained at 34$^{\circ}C$ and 80atm. After SCCD treatment, the physicochemical properties of cement matrices were analyzed to evaluate the effectiveness of accelerated carbonation reaction. Conversion of parts of portlandite to calcite by the carbonation reaction with SCCD was verified by XRD (X-ray diffraction) analysis and the composition of portlandite and calcite was estimated using thermogravimetric (TG) data. After SCCD treatment, tile cement density slightly increased by about 1.5% regardless of the SCCD treatment time. The leaching behavior of cement, tested in accordance with an ISO leach test method at 7$0^{\circ}C$ for over 300 days, showed a proportional relationship to the square root of the leaching time, so the major leaching mechanism of cement matrix was diffusion controlled. The cumulative fraction leached (CFL) of calcium decreased by more than 50% after SCCD treatment. It might be concluded that the enhancement of the characteristics of a cement matrix by an accelerated carbonation reaction with SCCD is possible to some extent.

• 열처리공학회지
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• 제23권2호
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• pp.83-89
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• 2010

Diamond-like carbon (DLC) coating was studied to be a good tribological problem-solver due to its low friction characteristics and high hardness. However, generally hydrogenated DLC film has shown a weak thermal stability above $300^{\circ}C$. However, the silicon doping DLC process by DC pulse plasma enhanced chemical vapor deposition (PECVD) for the new DLC coating which has a good characterization with thermal stability at high temperature itself has been observed. And we were discussed a process for optimizing silicon content to promote a good thermal stability using various tetramethylsilane (TMS) and methane gas at high-temperature. The chemical compositions of silicon-containing DLC film was analyzed using X-ray photoelectron spectroscopy (XPS) before and after heat treatment. Raman spectrum analysis showed the changed structure on the surface after the high-temperature exposure testing. In particular, the hardness of silicon-containing DLC film showed different values before and after the annealing treatment.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.219.2-219.2
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• 2011

The oxyfluorination effects of electrospun carbon nanofibers (OFACFs) were investigated for $CO_2$ storage. Carbon nanofibers were prepared form poly acrylonitrile / N,N-dimethylformamide solution through electrospinning method and heat treatment. Chemical activation of carbon nanofibers were carried out in order to improve the pore structure. And the surface modification of activated carbon nanofibers was conducted by oxyfluorination to improve the $CO_2$ storage on effect of introduced functional groups. The samples were labeled CF (electrospun carbon nanofiber), ACF (activated carbon nanofibers), OFACF-1 ($F_2:O_2$ = 3:7), OFACF-2 ($F_2:O_2$ = 5:5) and OFACF-3 ($F_2:O_2$ = 7:3). The functional group of OFACFs was investigated by x-ray photoelectron spectroscopy analysis. The specific surface area, pore volume and pore size of OFACFs were calculated and pore shape was estimated by the BET equation. Through the adsorption isotherm, the specific surface area and pore volume significantly decreased by oxyfluorination.

• 한국재료학회지
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• 제23권1호
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• pp.24-30
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• 2013

Today, the modification of carbon foam for high performance remains a major issue in the environment and energy industries. One promising way to solve this problem is the optimization of the pore structure for desired properties as well as for efficient performance. In this study, using a sol-gel process followed by carbonization in an inert atmosphere, hollow spherical carbon foam was prepared using resorcinol and formaldehyde precursors catalyzed by 4-aminobenzoic acid; the effect of carbonization temperature and re-immersion treatment on the pore structure and characteristics of the hollow spherical carbon foam was investigated. As the carbonization temperature increased, the porosity and average pore diameter were found to decrease but the compression strength and electrical conductivity dramatically increased in the temperature range of this study ($700^{\circ}C$ to $850^{\circ}C$). The significant differences of X-ray diffraction patterns obtained from the carbon foams carbonized under different temperatures implied that the degree of crystallinity greatly affects the characteristics of the carbon form. Also, the number of re-impregnations of carbon form in the resorcinol-formaldehyde resin was varied from 1 to 10 times, followed by re-carbonization at $800^{\circ}C$ for 2 hours under argon gas flow. As the number of re-immersion treatments increased, the porosity decreased while the compression strength improved by about four times when re-impregnation was repeated 10 times. These results imply the possibility of customizing the characteristics of carbon foam by controlling the carbonization and re-immersion conditions.

• Carbon letters
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• 제28권
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• pp.66-71
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• 2018

To improve the flame retardant performance of cellulose fibers, fluorine functional groups were introduced under various controlled fluorination conditions. The properties of the fluorinated cellulose fibers were analyzed by X-ray photoelectron spectroscopy and a thermogravimetric analysis. The fluorine functional group content in the fluorinated cellulose fibers increased with an increase in the fluorination temperature. However, the fluorination reaction increased the char yield and decreased the rate of degradation of the cellulose fibers by introducing donors, enabling the formation of a thick and compact char layer. Therefore, the flame retardant properties of cellulose fibers were improved following the fluorination treatment.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1199-1202
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• 2005

Inside of working PDP, there exist highly reactive conditions in the gap between two glass panels. MgO film and phosphor have been investigated as a function of discharge, also phosphor and sealing frits have been investigated as a function of temperature. Changes of impurity generation of MgO, phosphor and sealing fits were measured by using x-ray photoelectron spectroscopy (XPS) and quadropole mass spectroscopy (XPS) and quadropole mass spectrometer (QMS). Impurities such as CO, $CO_2$, OH and $H_2O$ were increased during discharge and heating treatment. Gaseous impurities such as carbon compounds and water deteriorated the characteristics of PDP operation during of lifetime. So metal is used to remove the impurities of phosphor and sealing frits during hearting, the result that the quantity of the impurities such as carbon monoxide and water was reduced.

• Carbon letters
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• 제11권2호
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• pp.127-130
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• 2010

Boron doped fullerene $C_{60}$ ($B:C_{60}$) films were prepared by the thermal evaporation of $C_{60}$ powder using argon plasma treatment. The morphology and structural characteristics of the thin films were investigated by scanning electron microscope (SEM), Fourier transform infra-red spectroscopy (FTIR) and x-ray photo electron spectroscopy (XPS). The electrochemical application of the boron doped fullerene film as a coating layer for silicon anodes in lithium ion batteries was also investigated. Cyclic voltammetry (CV) measurements were applied to the $B:C_{60}$ coated silicon electrodes at a scan rate of $0.05\;mVs^{-1}$. The CV results show that the $B:C_{60}$ coating layer act as a passivation layer with respect to the insertion and extraction of lithium ions into the silicon film electrode.