Carbon
Highly saturated lithium-graphite intercalation compounds (of a composition LiC 2 -LiC 4 ) synthesized under high-pressure conditions were investigated using X-ray diffraction. It was shown that these compounds present the structure with hexagonal unit cell with a parameter 8.63 , c = 3I c = 3 3.7 = 11.1 . The most probable stoichiometry for this unit cell is LiC ...
Adsorption from binary liquid mixtures of completely miscible components of different polarity was studied, in order to characterize the adsorption properties of commercial activated carbons. The excess adsorption isotherms were measured for three binary liquid systems: acetone + n-heptane, acetone + benzene, and benzene + n-heptane on four activated carbons of various ash content. Textural characteristics...
New stage 1 potassium-graphite intercalation compound was recently reported. This compound differs from those already known by its structure, which includes two metal layers in the same gallery. It has roughly KC 4 stoichiometry. This compound was studied under high quasi-hydrostatic pressures up to 25 kbar. From the volume vs pressure measurements and X-ray diffraction studies, it follows...
A chemical vapor deposition (CVD) apparatus under high gas pressure up to 1.0 MPa was experimentally fabricated. The high-pressure CVD with methane as raw material gas and argon as carrier gas was carried out, and carbon film was obtained on a graphite substrate at temperatures of 1673 to 2373 K and total gas pressure 40 KPa to 1.0 MPa. In the experimental pressure range, as total gas pressure increases,...
Shock synthesis of diamond was carried out at pressures of 26, 55, and 83 GPa by applying a quenching technique; a thin graphite plate was sandwiched by the copper heatsink disks. Successful suppressing of reverse transition to graphite (regraphitization) was achieved in the present technique. Thin sections were prepared from the recovered samples to observe distribution of the products between...
This paper reports the Raman spectra, obtained by using an excitation laser at 1064 nm, of carbon-based materials characterised by different microstructural properties and structural perfection. The use of a NIR excitation evidences new aspects of Raman activity in carbons. The E 2 g mode at 1582 cm - 1 in HOPG does not show dispersion to 1064 nm. On the other hand, in polycrystalline...
Thin film objects on the order of one micron width, whose contrast in the electron micrographs is distincly different from the original microgrid, are frequently found in the transmission electron micrographs obtained from a marketing microgrid. The electron diffraction pattern of their films usually shows hexagonal symmetry, and a measured lattice constant is a 0 =0.907 nm. The value is...
The adsorption of dysprosium ions onto activated charcoal from aqueous solution has been investigated in relation to pertinent variables, such as shaking time, pH, concentration of dysprosium ions, and temperature. The conditions leading to maximum adsorption have been established. The adsorption of dysprosium ions obeys the Langmuir and the Dubinin-Radushkevich isotherm equations. Thermodynamic...
In order to deepen our understanding of the air-blowing reaction of pitch as a precursor of carbon fiber, aromatic hydrocarbons having 2 to 3 rings were selected as pitch models, and structural analyses of their air-blown products were conducted using FD-MS, GC-MS, NMR, and FT-IR spectroscopies.Alkyl-substituted aromatic compounds polymerized with methylene, biphenyl-type, and ether bonding, leading...
The morphologies of lanthanum-filled carbon nanotubes and nanoparticles, made by arc-discharging carbon-La 2 O 3 composites, were examined with high-resolution transmission electron microscopy and selected-area electron diffraction technique. The HRTEM images and corresponding SAED patterns obtained from the arc-discharge product confirmed that α-LaC 2 nanocrystals, most of...
Infrared (IR) spectroscopy was used to study the solid products of the thermochemical degradation reaction of poly(vinylidene chloride) foils. Samples of foils heated at 200°C in air and in the range of 300-650°C in ammonia atmosphere. The degradation reaction produces new carbonaceous material with semiconducting properties.
Graphite rod specimens containing different sizes of artificial imitative defects simulated with carbonized paper, were manufactured experimentally and subjected to a round robin test of non-destructive inspection (NDI). The position of each defect in the rod was experimentally confirmed by a series of NDIs. This report deals with the results of destructive tests performed as the final step of the...
A dilute stream of carbon black particles was introduced into the postflame gases of premixed, high-pressure, both fuel-lean and rich ethylene-air laminar flames. The rate of oxidation of carbon black particles was measured using scattering and absorption techniques to determine the particle size, concentration, and number density as a function of distance and, hence, burn-off. The reactivity of...
In this work we study the carbonization resulting from an intumescence phenomenon of the fire-retardant formulation: ethylene terpolymer-ammonium polyphosphate/pentaerythritol. Characterisation of the intumescent coating is carried out using infrared spectroscopy and MAS-NMR of the solid state. The study shows the formation of organic phosphocarbonaceous esters, which limits depolymerisation or the...
Pitch oxidation by air-blowing has been studied as a possible method to modify pitch properties for composite preparation. Two commercial coal-tar pitches, an impregnating pitch and a binder pitch, were air-blown at temperatures between 250-300°C, for 18 and 14 h, respectively, to produce pitches of similar softening point ranging from 148 to 223°C. Parent and treated pitches were characterized...
We present experimental results on stage stability and stage transition in H 2 SO 4 -GDICs by X-ray measurements, and electronic energy state by UV/VIS spectrophotometer measurements. From the results of X-ray measurements, it is shown that the changes of stage and d c value are irregular and occur randomly, and that the penetration of H 2 O molecules into the intercalated...
The reaction between graphite fluoride and ferric chloride was observed in the temperature range of 300 to 400°C. The graphite fluorides used for this reaction have an sp 3 electronic structure and are electrical insulators. They can be made by fluorinating either carbon fibers or powder having various degrees of graphitization. Reaction is fast and spontaneous and can occur in the presence...