간행물
Carbon Letters KCI 등재 Carbon letters
- 발행기관 한국탄소학회
- 자료유형 학술지
- 간기 격월간
- ISSN 1976-4251 (Print)2233-4998 (Online)
- 수록기간 2000 ~ 2023
- 주제분류 자연과학 > 자연과학일반 자연과학 분류의 다른 간행물
- 십진분류KDC 530DDC 620
권호리스트/논문검색
Vol.8 No.2 (2007년 6월) 8건
1.
2007.06
구독 인증기관 무료, 개인회원 유료
The application of Carbon and graphite based materials in unprotected environment is limited to a temperature of 450℃ or so because of their susceptibility to oxidation at this temperature and higher. To over come these obstacles a low cost chemical vapour reaction process (CVR) was developed to give crystalline and high purity SiC coating on graphite and isotropic C/C composite. CVR is most effective carbothermal reduction method for conversation of a few micron of carbon layer to SiC. In the CVR method, a sic conversation layer is formed by reaction between carbon and gaseous reagent silicon monoxide at high temperature. Characterization of SiC coating was carried out using SEM. The other properties studied were hardness density and conversion efficiency.
3,000원
2.
2007.06
구독 인증기관 무료, 개인회원 유료
A series of activated carbons (ACs) were derived from sugarcane bagasse under two activation schemes: steam-pyrolysis at 600-800℃ and chemical activation with H3PO4 at 500℃. Some carbons were treated at 400, 600℃, or for 1-3 h, and/or in flowing air during pyrolysis of acid-impregnated mass. XRD profiles displayed two broad diffuse bands centered around 2θ=23 and 43˚, currently associated with diffraction from the 002 and 100/101 set of planes in graphite, respectively. These correspond to the interlayer spacing, Lc, and microcrystallite lateral dimensions, La, of the turbostratic (fully disordered) graphene layers. Steam pyrolysis-activated carbons exhibit only the two mentioned broad bands with enhancement in number of layers, with temperature, and small decrease in microcrystallite diameter, La. XRD patterns of H3PO4-ACs display more developed and separated peaks in the early region with maxima at 2θ=23, 26 and 29˚, possibly ascribed to fragmented microcrystallites (or partially organized structures). Diffraction within the 2θ=43˚ is still broad although depressed and diffuse, suggesting that the intragraphitic layers are less developed. Varying the conditions of chemical activation inflicts insignificant structural alterations. Circulating air during pyrolysis leads to enhancement of the basic graphitic structure with destruction and degradation in the lateral dimensions.
4,000원
3.
2007.06
구독 인증기관 무료, 개인회원 유료
Activated carbons were prepared by impregnation of crushed clean date pits in concentrated solutions of phosphoric acid or zinc chloride followed by carbonization in absence of air at 600℃. Steam-activated carbon was prepared by gasifying 600℃-carbonization product at 950℃ to a burn-off = 50%. KOH- activated carbon was prepared by impregnating date pitscarbonization product obtained at 450℃ in concentrated KOH solution followed by carbonization at 840℃. Textural properties of these carbons were determined from nitrogen adsorption at -196℃ and the chemistry of the carbon surface was investigated by determination and of the surface carbon-oxygen (C-O) groups using bases of variable strength and dilute HCl. The adsorption of endosulphan at 27℃ on all the carbons prepared was undertaken. Adsorption of this pesticide at 32 and 37℃ was also undertaken for steam-activated and KOH-activated carbons. Phosphoric acid-activated carbons and steamactivated carbons are mainly microporous and have high surface concentration of C-O groups of acidic nature. Steamactivated and KOH-activated carbons exhibited surface areas 〉 1000 m2/g and contain micro and non-micrpores. The adsorption of endosulphan was related to the surface area of non-micropores and was retarded by the high concentration of surface C-O groups. The thermodynamic properties indicated the feasibility of the adsorption process and the possible regeneration of the carbon for further use.
4,000원
4.
2007.06
구독 인증기관 무료, 개인회원 유료
In this work, activated carbon (AC) after HNO3 modification was used as the support during the production of supported TiO2 to increase the high deposition efficiency and the photocatalytic activity. The results of N2 adsorption showed that the BET surface area of samples decreased with an increasing of the concentration of HNO3 due to the penetration of TiO2. From XRD data, a single crystal structure of anatase peak was observed in diffraction patterns for the AC coated with titanium complexes. From the SEM results, almost all particles were aggregated with each other at the carbon surface and AC was covered with TiO2 particles in all of the samples. The EDX spectra show the presence of C, O, Ti and other elements. It was also observed a decreasing of amount of C content with increasing Ti and O content from the EDX. The results of FT-IR revealed that the modified AC contained more surface oxygen bearing groups than that of the original AC. The effect of surface acidity and basity calculated from Boehm titration method was also evaluated from correlations as a function of NaOH, NaHCO3, and Na2CO3 uptake. The surface modification of AC by HNO3 leads to an increase in the catalytic efficiency of AC/TiO2 catalysts, and the catalytic efficiency increases with increasing of HNO3 concentration.
4,000원
5.
2007.06
구독 인증기관 무료, 개인회원 유료
Properties of carbon blacks and carbon black/SBR rubber composites filled by surface modified carbon blacks were examined. Although the specific surface area of carbon blacks increased after the surface modifications with heat, acid, and base, there were no obvious changes in resistivity. The composites filled by heat treated carbon blacks showed a higher tensile strength and elongation than those filled by raw blacks. The acid and base treated carbon blacks filled composites also showed higher tensile strength but similar elongation values with those filled by raw blacks. With increasing loading ratio, both tensile strength and elongation increased, and appeared a maximum value at 30-40 phr. Modulus at 300% strain remained increasing with further loading of carbon blacks. At the same loading, the heat treated black filled composites showed similar modulus values with composites filled by raw blacks but for base and acid treated black filled composites much higher values were obtained. After the surface modification, the functional groups which played an important role in reinforcement action were changed.
4,000원
6.
2007.06
구독 인증기관 무료, 개인회원 유료
The effect of cobalt precursor on the structure of Co supported multi-walled carbon nanotubes (MWCNTs) were studied by using X-ray photoelectron spectroscopy (XPS). MWCNTs were treated with a mixture of nitric and sulfuric acids and decorated with cobalt and/or cobalt oxides via aqueous impregnation solutions of cobalt nitrate or cobalt acetate followed by reduction in hydrogen. XPS was mainly used to investigate the phase of cobalt on MWCNTs after reduction with H2 flow at 400℃ for 2 h. Higher cobalt-nanoparticle dispersion was found in the MWCNTS prepared via cobalt nitrate decomposition. A typical XPS spectrum of Co 2p showed the peaks at binding energy (BE) values equal to 781 and 797 eV, respectively. It is found that cobalt nitrate supported MWCNTs is more dispersive and have catalytic activity than that of cobalt acetate supported MWCNTs at same preparation condition such as concentration of precursor solution and reduction environment.
4,000원
7.
2007.06
구독 인증기관 무료, 개인회원 유료
In this study, commercially available pitch-based carbon fibers of general grade were post-heat-treated using a boxtype high temperature furnace at 1800℃, 2000˚, 2200℃, and 2400℃, respectively. The fundamental characteristics of each heat-treated carbon fibers were investigated in terms of chemical composition, morphology, thermal stability, X-ray diffraction, single filament tensile test, and electrical resistivity. The result showed that the fiber properties were significantly influenced by the post-heat-treatment, indicating the greater effect with increasing treatment temperature. The carbon contents, thermal stability, and tensile properties of the carbon fibers used here were further increased by the post-heat-treatment, whereas the d-spacing between graphene layers and the electrical resistivity were reduced with increasing post-heat-treatment temperature.
4,000원
8.
2007.06
구독 인증기관 무료, 개인회원 유료
In this work, activated carbons (ACs) were prepared from polystyrene-based cation-exchangeable resin (PSI) by a chemical activation with KOH as an activating agent. The surface morphologies were observed by using SEM, and the textural properties were investigated by using nitrogen adsorption at 77 K. From the experimental results, it was found that the well-developed micro- and mesopores were produced by a chemical activation, and the textural properties including specific surface areas and pore volumes were greatly enhanced. The electrochemical behaviors of the ACs showed similar phenomena with that of textural properties. These results indicated that KOH activation played an important role in the changes of surface, and pore structures, resulting in enhancing the electrochemical properties of the ACs prepared in present work.
3,000원
