Addition Of Carbon Powder Research Articles

Exploration of Reverse Micelle Synthesis of Carbon-Supported LaMnO3

Reverse micelle (RM) based synthesis of carbon-supported perovskite type oxide was investigated. By using cyclohexane as oil phase, six kinds of nonionic surfactants were tested for the formation of the revere micelle dispersions containing aqueous solutions of mixed nitrates of and (RM-N) and tetramethylammonium hydroxide (RM-A) at the water/surfactant molar ratio of 3. RM-A was found to be more difficult to form compared with RM-N or the RM containing pure water. At a temperature range of 5-25°C, it was given only by the surfactants with hydrophilic-lipophilic balance (HLB) values of 10.0-10.9. Phase diagrams of oil-surfactant-alkaline solution (or pure water) were constructed at 5 and 15°C for the best two surfactants, i.e., -nonylphenyl ether and -lauryl ether. Mixing RM-N and RM-A together gave the RM containing a mixed hydroxides-precursor (RM-P), which was further converted into carbon-supported through a series of treatments including the addition of carbon powder and calcination in atmosphere at 600°C. The size of RM-P as well as that of the grains supported on carbon could be controlled well by selecting The carbon-supported proved to be highly active for the electrochemical reduction of oxygen. © 2004 The Electrochemical Society. All rights reserved.

Effect of carbon addition on the microstructure of Si3N4–Cfiber composites using semiconductor-waste Si sludge

Si3N4–Cfiber composites using waste-Si sludge were fabricated by hot pressing at 1850 °C for 2 h with and without the addition of carbon powder. The composites were composed of small amounts of β-Si3N4, O′SiAlON, SiC and Y2SiO5 regardless of carbon powder addition. In the composite without the addition of carbon powder, most of the carbon fibers were graphitized with fine particles. Furthermore, many cavities were observed in the interior regions of C-fibers as well as at the interfaces of Si3N4/Cfiber caused by the decomposition of them. However, in the composite with 3 wt.%C powder added, the core regions of C-fibers still existed in an amorphous. The average size of a matrix grain in the composite using 3 wt.%C powder was slightly finer than that of composite fabricated without using carbon powder, which was caused by the existence of nanometer-sized SiC particles.

Preparation and properties of glass-ceramic materials obtained by recycling goethite industrial waste

The recycling of toxic goethite waste, originated in the hydrometallurgy of zinc ores, in glass-ceramic matrices has been studied. Oxide compositions suitable to form glasses were prepared by mixing the goethite waste with granite scraps and glass cullet, yielding the following oxide composition (wt%): SiO2, 44.6; Al2O3, 3.3; Fe2O3, 25.5; MgO, 1.6; CaO, 4.5; Na2O, 5.9; PbO, 3.1; ZnO, 6.5; K2O, 1.0; TiO2, 2.0; other 2.0. By proper addition of carbon powder, the initial Fe3+/Fe2+ ratio (12) of glasses melted in air at 1450 °C was approximated to the stoichiometric value of magnetite (2) to obtain high nucleation and crystallization rates. The heat treatment of iron supersaturated goethite glasses above 630 °C led to the formation of magnetite nuclei with a high tendency to grow and coalesce with time. The crystallization of pyroxene, occurring on the magnetite crystals above 800 °C, was found to be influenced by the nucleation period, so that the highest crystalline volume fraction, V f (0.80–0.85), was obtained for 90–120 min nucleation time at 670 °C and 120 min crystallization at 860 °C.

高圧側で燃焼中断する固体推進薬

PPG+AP composite propellants have exhibited extinction behavior when the chamber pressure is increased to some value, Pext, extinction pressure. The extinction pressures were found to be 1) independent of the pressurization rates, 2) altered by addition of carbon powder and 3) diminished by using propellants with higher PPG ratios. By thermal analysis of the propellants used and microscopic observation of the extinguished surfaces it is presumed that these phenomena are due to the differences in decomposition rates between PPG and AP at various chamber pressures and their decomposition enhancement by carbon addition.

The effect of addition of carbon powder to samples in liquid secondary ion mass spectrometry: Improved ionization of apolar compounds

AbstractAddition of carbon or graphite powder, to either the matrix or the sample if no matrix is used, facilitates the formation of sample ions. For most of the compounds investigated, [M + H]+ ions are observed. For long‐chain alcohols, [M − 1]+ ions are formed. This new analysis method allows mass spectra of compounds, that hitherto were difficult or impossible to ionize, using liquid secondary mass spectrometry to be obtained and enhances the signal intensity of poorly ionizable compounds. Using this technique in the negative ion mode, a spectrum of Fomblin® can be obtained which is suitable for calibration purpose over a mass range of 1400 u. The observed effect is possibly due to enhancement of the field strength at the sample surface in the presence of carbon powder. No evidence of contamination of the ion source was visible after four weeks of intensive use of this technique.

Electrochemistry of hydrophobic Nafion gels Part 3. Preconcentration and electrochemical detection of cationic and neutral organic compounds in hydrophobic Nafion gels made from various n-alkylphosphates

Hydrophobic Nafion® gels prepared with trialkyl phosphates can be used to detect selectively not only cationic but also neutral organic compounds, such as lawsone or juglone, in aqueous media owing to the concentration of the substrate in the gel layer as a result of the organophilic character of the gel. Addition of carbon powder to the gel increases the level of the signal recovered.

Electrical conductivity of iodine adducts of nylon 6 and other non-conjugated polymers

Iodine-nylon 6 adducts containing 70 to 90wt% iodine have been prepared by heating iodine and nylon 6 at 115 and 145° C. The electrical conductivity (σ) of the adduct increases with increase in the iodine content and the iodine-nylon 6 adduct containing 90wt% iodine and prepared at 145° C gives σ = 10−3 S cm−1 at 25° C. Infrared, nuclear magnetic resonance (1H and13C{1 H}), and powder X-ray diffraction analysis of the adduct show a profound change of the structure around the amide group of nylon 6 and suggest the formation of a-C=NH+-group in the reaction of nylon 6 with iodine. The temperature dependences of σ of the idoinenylon 6 adducts prepared at 115° C give activation energies of 51 to 92 kJ mol−1 depending on the iodine content. Addition of carbon powder to the iodine-nylon 6 adduct causes an increase in electrical conductivity. Other polymers (aliphatic and aromatic nylons, poly(vinyl alcohol), poly (tetrahydrofuran), poly(N-vinylpyrrolidone), poly (4-vi nylpyridine), and poly(acrylonitrile)) which have lone pair or π-electrons also form iodine adducts containing 70 to 95 wt % iodine and the adducts show an electrical conductivity in the range of 10−5 to 10−2 S cm−1. Among the iodine adducts, those of poly(vinyl alcohol) and poly (tetra hydrofuran) show electrical conductivities as high as 1.5 X 10−2 S cm−1 when the adducts contain about 90 wt% iodine.

銅-炭素繊維複合材料の往復すべり摩耗特性

The effect of fiber arrangements and additional elements on reciprocating sliding wear characteristics of copper-carbon fiber composite was studied. Results obtained in this study were as follows:(1) The wear volume of the copper-carbon fiber composite appeared to be smaller than that of copper alloys.(2) The wear volume of the copper-carbon fiber composite became larger, as the sliding load increased and the volume fraction of carbon fiber increased beyond 30 volume percent.(3) The effectiveness of fiber arrangement in reducing the wear volume was the highest in the random arrangement, medium in the direction perpendicular to the unidirectional fiber direction and the lowest in this fiber direction.(4) The wear volume of the composite was decreased by the addition of Sn and Zr. However, the addition of these elements could not achieve the isotropic wear characteristics of the composite.(5) It was found that the isotropic wear characteristics of the composite could be obtained by the addition of carbon powder. The isotropic wear characteristics and the reducing wear volume of the composite could be attained by the addition of Zr and carbon powder together.