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Hollow mesophase pitch fibers with rather thin diameter were successfully prepared by spinning through a C-shaped capillary. Die-swell was found to be the main factor affecting the formation of hollow fiber, and this was controlled by varying the spinning temperature. After carbonization at 1000°C, the hollow fibers possess a relatively small outer diameter of 21μm and an inner diameter of 6μm, and...
We have applied the near-edge X-ray absorption fine structure (NEXAFS) technique to investigate the electronic and structural properties of specialty carbonaceous materials and anode electrodes made from the synthesized carbons. The carbon K-edge features of the carbonaceous materials were characterized by two relatively sharp resonances at 286 and 293eV and a broad peak centered at 305eV. A peak...
Carbon nanotubes (CNs) are electrically small particles at infrared and microwave frequencies. The Mossotti–Clausius formalism for estimating the effective permittivity dyadic of a dilute composite containing CN inclusions is described, and simplifications for certain orientational statistics are discussed. The polarizability dyadic of an electrically small CN is estimated from that of an infinitely...
The purpose of this study is to develop a measurement technique for in situ monitoring of the degradation processes of thermal-resistance materials, such as C/C (carbon/carbon) composites, in high temperature fields. Spatially, spectrally and temporally resolved images of emission from diatomic molecules were observed in an acetylene–air flame by a spectrovideo camera, assembled by combining a monochromator...
To prohibit skin-core structure from appearing in mesophase pitch based carbon fiber (CF) with a large diameter (30–50μm), measures such as decreasing oxidation temperature, prolonging holding time and increasing the oxygen partial pressure in the oxidative atmosphere were taken. EPMA (electron probe X-ray micro-analyzer) was utilized to detect the oxygen content distribution along the diameter of...
Vapor-grown carbon fibers (VGCF) were grown from a methane-hydrogen mixture on a reconstituted graphite support using different catalyst precursors, the [Fe 3 (CO) 12 ] complex being found to be the most efficient for the production of VGCF. The fibers thus produced were characterized and submitted to different oxidative treatments, namely nitric acid, plasma, air and carbon dioxide...
A series of activated carbon fibers (ACFs) produced from organometallics compounds such as Y(acac) 3 or Al(acac) 3 /pitch composites were characterized. The pore-size, surface state and graphitic crystallite size were examined by means of N 2 adsorption isotherm, X-ray photoelectron spectroscopy and X-ray diffraction (XRD) analysis. The presence of Y or Al increased the pore-size...
A reactor is described for generating fullerenes from hydrocarbon gas or vapor. Distinguishing features are a thermal system in which the fullerene product is not exposed to destructive energetic photons (as in an arc) and ease of control. Acetylene was chosen as the first feedstock to reduce the hydrogen content. Argon is the carrier gas. The reactor is a radio-frequency induction heated cylinder...
A Raman scattering characterization is reported that confirms the preparation of single wall carbon nanotubes (SWNT) by the solar energy route. The results are presented for samples synthesized with various catalysts—mixtures of Ni and Co (Y, La)—and compared to those obtained from electric arc discharge or laser ablation. In the light of the calculations of the vibrational spectra of SWNT by Eklund...
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