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The absorption of sodium vapour in commercial cathode materials for aluminium electrolysis has been studied within the range 1020–1227 K and 3–600 Torr. The absorption increases strongly with decreasing degree of graphitization. The absorption of sodium in the commercial materials can be described as a BET isotherm with calculated surface area between 9 and 124 m 2 /g. The measured surface...
Powdered activated carbon has been prepared from lignitic coal of Lakhra (Pakistan) by a chemical activation method using ZnCl 2 as an activating agent. Different process variables have been established after a series of experiments and an impregnation ratio of 1:2, an activation temperature of 650 °C and a duration of 1 hour have been found to be appropriate for its preparation. It has been...
The textures and microstructures of three different experimental mesophase pitch-based ribbon fibers were studied using the complementary techniques of scanning and transmission electron microscopy and wide angle X-ray diffraction. The effect of mesophase pitch precursor and capillary entry design on the structure and heat transfer capabilities of these ribbon-shaped fibers was investigated. It was...
Binary organic—inorganic gels, in which a carbonaceous gel obtained from a coal tar pitch and a zirconia gel are combined, were prepared as precursors for carbothermal reduction with and without simultaneous nitridation to form Zr(C,O,N) solid solutions. Zirconium(IV) propoxide as the starting material for zirconia was hydrolyzed in the presence of acetylacetone in order to avoid undesirable precipitation...
High-temperature carbons have been prepared from kraft lignin on thermal treatment up to 3073 K. The structure of these high-temperature carbons has been studied by X-ray diffraction and Raman spectroscopy. The interlayer spacing obtained from XRD approaches the d 002 value of graphite as the heat treatment temperature is increased. The (002) diffraction peak of the higher temperature carbons...
Although carbon fiber reinforced carbon matrix (C/C) composites are used in the aerospace and utility industries, carbon materials oxidize readily at temperatures above 425 °C. A variety of coatings have been used to protect C/C composites from oxidation. The thermal expansion mismatch creates microcracks that could result in catastrophic failure. To alleviate these difficulties, we have used the...
Attempts to intercalate the chloroaluminate complexes CuAl 2 Cl 8 and CdAl 2 Cl 6 into graphite have resulted in the synthesis of two new first stage compounds, C 22 CuAl 2 Cl 8.5 and C 10 Cd 0.2 AlCl 3.7 . The former possesses an oblique inplane unit cell, the latter a rectangular cell, commensurate with that of the host...
Preparation of an antibacterial activated carbon fiber with mesopores was attempted. Phenolic resin containing cobalt as an activation catalyst and silver as an antibacterial agent was spun, stabilized, carbonized and activated in steam. The number of the metal particles increased with as activation proceeded and reached to 100–200 nm in diameter at the largest. The activated carbon fiber with 72...
The theoretical model for the impact of polycrystalline graphite beams previously presented by the authors has been improved by the addition of an empirical model of the internal friction of the specimen. This takes the form of a velocity dependent damping term included in the vibrational equation for the beam. A graph showing the theoretically predicted force history is shown, which shows a similar...
The fiber length distributions of carbon fibers grown on alumina substrates by the vapor phase decomposition of benzene have been measured at different lengthening times in the temperature range of 1283–1353 K and at two concentrations of benzene. The proportion of longer fibers increased with lengthening time. A two-parameter model has been used to compare the calculated and experimental fiber length...
Nano-scale structures of a mesophase pitch based carbon fiber were characterized using a high-resolution scanning electron microscope (HR-SEM) and a scanning tunneling microscope (STM). Fibril was found to be sectioned by a number of pleat units, being aligned parallel along the fiber axis. The periodical size, thickness and height of pleat unit was estimated as 30–60 nm, 20–30 nm and around 7 nm,...
Isocyanate functional groups can readily react with sterically accessible acidic functional groups on carbon fiber surfaces. Solvent effects on these reactions were investigated. Polar solvents such as DMF seem to favor this reaction. The grafting efficiency of isocyanate terminated-oligomers decreased with increasing molecular weight even though the total weight gain was higher when higher molecular...
A (6, 12) Lennard-Jones formulation is used to evaluate the enthalpy of formation of multilayered coaxial or scroll-like carbon nanotubes. The role of various parameters—such as interlayer spacing, value of the innermost radius, number of layers—is examined. Most of the nanotubes examined turn out to be metastable, with a small but positive heat of formation.
Activated carbons offer a large spectrum of pore structures and surface chemistry for adsorption of gases, which are being used to design practical pressure swing and thermal swing adsorption processes for separation and purification of gas mixtures. The activated carbons are often preferred over the zeolitic adsorbents in a gas separation process because of their relatively moderate strengths of...
The interaction of benzene with ternary GICs MHgC 8 (M = K, Rb) has been investigated and new quaternary compounds MHgC 8 (C 6 H 6 ) 2 were obtained. X-ray data, Fourier transform of 001 reflections and spin-lattice relaxation measurements show that benzene molecules intercalate into the empty galleries of the amalgam GICs.
Unidirectional, pitch-based-matrix composites fabricated from PAN-based Courtaulds fibres were oxidised in air at temperatures of 420 and 730°C to low extents of burn-off (less than 3.5%). Material loss occurred primarily at fibre-matrix interfaces at the edge regions of the composites and, in the case of the lower temperature heat-treated materials, in the areas close to internal pores and cracks...
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