Acheson Graphite Research Articles

Intercomparison between a single particle soot photometer and evolved gas analysis in an industrial area in Japan: Implications for the consistency of soot aerosol mass concentration measurements

Abstract Mass concentrations of soot (typically comprising black and elemental carbon; BC and EC, respectively) aerosols, were measured at Yokosuka city, an industrial region in Japan in the early summer of 2014. The results of laser–induced incandescence (LII) and evolved gas analysis (EGA) techniques were compared using a single particle soot photometer (SP2) and semi-continuous elemental/organic carbon analyzer (EC/OC analyzer), respectively. We revisited the procedure of SP2 calibration with a focus on investigating the relationship between LII intensity ( S LII ) and refractory BC (rBC) mass per particle ( m PP ) for some BC-proxies in the laboratory, as well as for ambient rBC particles in order to discuss the uncertainty of the SP2. It was found that the m PP – S LII for the fullerene soot and carbon black particles agreed well within 3% and 10%, respectively, with that for ambient rBC particles. This is the first time to suggest the use of carbon black as a reference material. We also found that the m PP – S LII for the aqueous deflocculated Acheson graphite particles with the correction factor given by Baumgardner et al. (2012) was still biased by around +20% to that for ambient rBC particles. EC quantified by the semi-continuous EC/OC analyzer using a thermal-protocol similar to that of Interagency Monitoring of Protected Visual Environments (IMPROVE–like), systematically showed higher concentrations than rBC measured by the SP2. The uncertainties related to SP2 cannot fully account for this difference. This result was likely caused by the contribution of charred organic materials to EC, which can be affected significantly by thermal-protocols for the EGA. The consistency and differences between rBC and EC are discussed with regard to comparing their respective mass concentrations.

Gas chromatographic determination of adsorption isotherms, spreading pressures, london force interactions and equations of state for n-alkanes on graphite and carbon blacks

Adsorption isotherms were obtained for C 6C 9 n-alkanes on a graphite and two carbon blacks at 363°K by gas chromatography using the peak maximum elution method. The surface areas of the adsorbents were obtained by applying the Brunauer—Emmett—Teller equation, and found to depend on the hydrocarbon used. Increasing differences from that found with nitrogen at 77°K were observed with increasing chain length of the hydrocarbon. This can be attributed to adsorbate—adsorbate lateral interactions. The London component of the surface free energy of the solid, v L 2, was calculated from the spreading pressure. The values obtained show that the homogeneity of the solids increases in the order V3 < V3G < Acheson graphite. On the other hand, for the same adsorbent, v L 2 depends on the hydrocarbon used. Equations of state were also determined. It was found that for a spreading pressure below 2 mN m −1 the n-alkanes obey the ideal equation, but spreading pressures above 2 mN m −1 the behaviour of the hydrocarbons increasingly deviates from that of ideality as the spreading pressure and chain length of the n-alkane increase. This is attributed to the increase in adsorbate—adsorbate lateral interactions.

Decomposition du methane sur le carbone aux tres hautes temperatures et sous basses pressions

The decomposition of methane on pyrocarbon as deposited in the course of the reaction has been investigated at high temperatures (1000–2000°C) and low pressures (⩽ 10 −2 Torr). Experiments have been carried out with electrically heated filaments made of amorphous, pyrolytic or graphitic carbon. Rates of decomposition are calculated from rates of molecular hydrogen formation. Results are very different from those reported previously about the decompositions of ethylene, acetylene, propadiene and benzene on the same substrates. 1. (1) Electron microscope observations never showed any evidence of pyrocarbon deposition (Fig. 4). However some indications do not exclude this possibility in the deep pores of the Acheson graphite. 2. (2) Electrical resistivity measurements confirm the smallness—or even the complete absence—of any pyrocarbon deposition (Fig. 5). 3. (3) Even after many series of ten hours reaction time, the kinetics of methane decomposition are still strongly dependent upon the type of sample. This fact supports also the conclusion that pyrocarbon deposition is absent (in contrast, the pyrocarbon deposited in similar experiments using unsaturated hydrocarbons makes all types of samples tend progressively to a standard chemical behavior). 4. (4) On smooth pyrocarbon surfaces, methane decomposition is hardly detectable; collision yields are of the order 10 −7 (as compared to 10 −4 for unsaturated hydrocarbons, Fig. 6). But with porous samples—especially Acheson graphite—appreciable decomposition occurs; the kinetics show then many similarities with those reported previously for unsaturated hydrocarbons decompositions: especially the reactivity of the carbon surface is temperature and pressure dependent (Figs. 1–3). The peculiar behavior of methane is explained in terms of chemical reactivity: unlike unsaturated hydrocarbons, methane does not undergo weakly activated chemisorption on the active sites of the carbon surface, and decomposition may then only occur after thermal accommodation of the gas molecules.

ChemInform Abstract: THE MECHANISM OF THE CHLORINE EVOLUTION ON DIFFERENT TYPES OF GRAPHITE ANODES DURING THE ELECTROLYSIS OF AN ACIDIC NACL SOLUTION

Abstract The behaviour of the electrode and the formation of chlorine were studied practically for porous graphite used in the industrial electrolysis of an aqueous NaCl solution only. In this investigation this was done for Acheson graphite electrodes and for highly orientated pyrolytic graphite electrodes of which the edge plane or the basal plane served as electrode surface. Voltammograms were determined by continuous scanning with different rates of the potential between a minimum and maximum value. From the experimental results it follows that two different surface compounds, the lp oxygen and the hp oxygen are formed on all the graphite electrodes investigated. In the stationary state lp oxygen is present at low potential and the hp oxygen at high potentials. The formation and the removal of each compound depends on the electrolytic conditions, especially on the maximum potential of the sweep. The conditions of the sweep determine whether these oxides are really present on the electrode surface during the anodic or the cathodic sweep. Chlorine is formed according to the Volmer-Heyrovsky mechanism on all the three types of electrodes. The current density, the transfer coefficient and the activation energy for the edge plane electrode and the Acheson graphite electrode are of the same order of magnitude, while for the basal plane electrode they deviate strongly.

The mechanism of the chlorine evolution on different types of graphite anodes during the electrolysis of an acidic NaCl solution

The behaviour of the electrode and the formation of chlorine were studied practically for porous graphite used in the industrial electrolysis of an aqueous NaCl solution only. In this investigation this was done for Acheson graphite electrodes and for highly orientated pyrolytic graphite electrodes of which the edge plane or the basal plane served as electrode surface. Voltammograms were determined by continuous scanning with different rates of the potential between a minimum and maximum value. From the experimental results it follows that two different surface compounds, the lp oxygen and the hp oxygen are formed on all the graphite electrodes investigated. In the stationary state lp oxygen is present at low potential and the hp oxygen at high potentials. The formation and the removal of each compound depends on the electrolytic conditions, especially on the maximum potential of the sweep. The conditions of the sweep determine whether these oxides are really present on the electrode surface during the anodic or the cathodic sweep. Chlorine is formed according to the Volmer-Heyrovsky mechanism on all the three types of electrodes. The current density, the transfer coefficient and the activation energy for the edge plane electrode and the Acheson graphite electrode are of the same order of magnitude, while for the basal plane electrode they deviate strongly.

Calorimetric Evidence for the Structure of Films adsorbed at the Solid/Liquid Interface: the Heats of Wetting of ‘Graphon’ by some n-Alkanes

EARLY work showed that the heat of wetting of graphitized carbon (for example ‘Graphon’) by non-polar liquids was largely independent of the precise nature of the liquid. In particular, in the alkane series, the number (n) of carbon atoms in the chain was said to have little effect on the heat of wetting of unit area of solid1–3. Robert4 suggested that alkane molecules were adsorbed parallel to the surface, that a methyl group and a —(CH2)2— unit occupied roughly equal areas (14 A2) and that a methyl group and a single methylene group were each adsorbed with an energy, relative to the liquid, of about 1,500 calories mole−1. On this basis the heat of wetting per unit area should rise slowly to a limiting value (dotted curve Fig. 1a). More recently, Robert5 measured the heat of wetting of several carbons by alkanes at 20° C: for some carbons (‘Vulcan 3’, ‘Spheron’) the heats of wetting varied only slightly with n, while for others (‘Graphon’, Acheson graphite) they increased rapidly. Robert offered no explanation of this behaviour, and it is inconsistent with his earlier proposal.

Iron as an impurity in colloidal graphite: its effect on thimble ionization chamber performance.

Small thimble chambers of the “compensated” type, consisting of a graphite-coated plastic cap with an aluminium collecting electrode of appropriate size, have been employed at the London Hospital for almost all routine measurements such as those of percentage depth dose. The plastic material used for the caps has been Perspex and the graphite coating has been obtained by painting the inside of the cap with a colloidal graphite preparation to a thickness of several thousandths of an inch. The size of the aluminium peg has then been adjusted empirically to provide the desired quality dependence characteristics. Until recently, Aquadag had been used for coating the cap, this being one of the preparations supplied by Messrs. Acheson Graphite Ltd. Graphite coatings formed from this preparation showed some tendency to flake off,* and a change was made to Dag in resin-alcohol in order to minimise this tendency. Recently a chamber cap was broken during the course of some experimental work, and was replaced by a new one, coated with Dag in resin-alcohol. It may or may not be relevant to state that this preparation was in fact supplied in an iron can, and had been in stock in our laboratory for several months. During subsequent experimental work with this chamber some suspicion was aroused that its response showed untoward quality dependence.

The distribution of temperature along a thin rod electrically heated in vacuo , III. Experimental

The present part is concerned with a detailed experimental verification of the main results obtained theoretically in the earlier parts. Thin rods of Acheson graphite were used for this purpose, and were found very suitable. In addition to the experimental data for the temperature distribution along rods of different lengths, and heated by alternating currents of different densities, one also needs for such a verification, data for the thermal and the electrical conductivities, and the spectral and the total emissivities of the surface, at different temperatures. These measurements also have been made. The observed temperature variation along the rod is itself used to determine the thermal conductivity and its temperature variation. The thermal conductivity is found to decrease and tend to a constant value at high tem peratures, as it should. The other physical constants are determined directly. At low temperatures the spectral emissivity is found to be much larger than the total emissivity, and they tend to approach each other at high temperatures. Further, the spectral emissivity is found to decrease rapidly with increase of wave-length, as in the case of metals. Coming back to the temperature distribution, the main results that are verified here relate to the range of validity of the logarithmic formula in the B -region of a long rod, the constants involved in the formula, the deviation from the formula as one moves further into the B -region, the effect of the temperature coefficients, the parabolic law of variation near the centre, and the nature of the deviation from the parabolic law in long and short rods as one moves further away from the centre.

Study on Consumption of Carbon Anodes in Electrolysis of Aqueons Solutions

In this report we compared consumption of three groups ot graphite eiectroaes, each consisting of three or four plates. We measured ratio of current used for consumption of carbon, total weight loss and ratio of sludge to consumption, by oxidation.The main difference between Acheson graphite and Jaban's graphite consists not in consumption by oxidation but in the ratio, of sludge to that, and according to small value of this ratio, about 0.2, Acheson graphite gives relatively small value of total consumption.

The Specific Heat of Graphite from 13° to 300°K

The specific heat of high-purity Acheson graphite prepared by the National Carbon Company has been measured from 13° to 300°K. In the region 13° to 54°K the Cp data follows a T2 dependence quite accurately in agreement with previous experimental work and recent theoretical investigations of specific heat in strongly anisotropic solids. On the basis of some recent studies for other highly anisotropic solids, it is suggested that the specific heat of graphite will eventually follow a T3 dependence at still lower temperatures. The derived thermodynamic functions, entropy, enthalpy, and free energy, have been determined by graphical integration and tabulated at integral values of temperature up to 300°K. The entropy of graphite at 298.16°K is 1.372±0.005 cal/g-atom deg, of which 0.004 is extrapolated from 13° to 0°K assuming the third law and the T2 dependence.

黒鉛電極に関する研究(第2報)

This report describes the oxidation-test of artificial graphite, natural graphite, petroleum coke and pitch cope with dry air at 500°C.We estimated their degrees of graphitization from combustibility (combustion curve).The results of this test corresponed with the degree of graphitization estimated from physical properties (specific gravity, electrical resistance etc.) and practical test (corrosion by electrolysis of alkali chloride solution).The Acheson graphite is manufactured from the Great Lake petroleum coke which has high combustibility, but its combustibility is lower than the product from pitch coke which has lower one than the Great Lake coke. Namely, on the combustibility, the relation of the raw material and its product is contrary.

Spectroscopic characteristics of ordinary Acheson graphite

Spectroscopic characteristics of ordinary Acheson graphite

High Temperature Electric Furnace with Acheson Graphite Spiral Heating Element

AbstractAn Electric Furnace specially adopted for P. C. E. Test has been made using Acheson Electrode Graphite as the heating element. Uniform heating zone, good regulation of the rate of heating and a fairly oxidizing atmosphere were obtained. The furnace operates on 20–28 Volts and 100–300 Amps. The Hot zone is approximately 3′ long in the centre of a tube 2 internal diam., 19” long.

Thermal and Electrical Conductivity of Graphite and Carbon at Low Temperatures

Thermal and electrical conductivities of graphite and carbon were measured at various temperatures in the range between −191°C and 100°C. Thermal conductivity of graphite was found to increase at an increasing rate as the temperature was lowered and two values were always found for Acheson graphite, a longitudinal and transverse conductivity, the latter being about ½ the former. This effect has not been reported for artificial graphite although Wooster reported an anisotropy in natural graphite with respect to thermal conductivity, the values along the axis being about four times that at right angles. X-ray patterns give no evidence of crystalline alignment in Acheson graphite and the explanation of this anisotropy has not been found. The electrical conductivity of graphite increases with rise of temperature as contrasted with the decrease of the thermal conductivity with temperature rise. Thus the Wiedmann-Franz law does not hold, nor is the Lorentz number a constant. Carbon shows no anisotropy. The thermal and electrical conductivities both increase with temperature rise, the thermal conductivity linear, in the temperature range −191° to 100°C.

Efficiency of the Electrolytic Separation of Chlorine Isotopes

The electrolytic separation coefficient α has been determined for the chlorine isotope separation in the electrolysis of sodium chloride solutions at a platinum anode. Flotation of purified NaCl crystals in ethylene dibromide was employed as the analytical procedure in determining the isotopic composition of samples. Densities of the ethylene dibromide as a function of temperature were separately determined. The electrolytic separation factor for Cl isotopes was found to be 1.0060±0.0005 for the temperature range 25° to 40°C. No significant dependence on either temperature or current density was observed. The coefficient on platinum (1.0060±0.0005) agrees with the value on Acheson graphite (1.0068±0.0014) which may be computed from the data of Yacouban.

The variation with temperature of the electrical resistance of carbon and graphite between 0 C. and 900 C.

The variation with temperature of the electrical resistance of specimens of amorphous carbon and of Acheson graphite has been determined for temperatures between 0° c. and 900° c. The results obtained are compared with those recorded by other investigators. The work is to some extent complementary to that of Powell and Schofield, who determined the thermal and electrical conductivities of the same materials between 750° c. and 2500° c. Two samples of Acheson graphite showed minima of resistance at about 390° c. and 430° c. respectively.

The thermal and electrical conductivities of carbon and graphite to high temperatures

The thermal conductivity K is derived in terms of the difference in temperature which, in the steady state, is set up between the axis and the surface of a rod or tube of the material when the latter is electrically heated in an evacuated enclosure. The electrical conductivity σ is derived in the course of the same experiment from measurements of the current flowing in, and the potential-difference across, a length of the rod located near the centre. Solutions of the heat-flow equations are obtained for the case in which K and the electrical resistivity ρ are not constant but vary with temperature in a linear manner. Experimental results are given for a variety of carbon consisting of 80 per cent of petroleum coke combined with 20 per cent of lampblack at temperatures up to about 2000° c. and for Acheson graphite up to about 2700° c. Evidence for the graphitization of carbon is obtained in that the results for this material at the highest temperatures tend to conform with those for graphite. At normal temperatures the Lorenz functions, Kρ/T of carbon and graphite are respectively about 17 and 200 times as great as the value normally obtained for metals. The values, however, decrease rapidly with increase in temperature, and at 1700° c. the Lorenz functions of both materials are only about 4 times as great as those of metals.

The thermal and electrical conductivities of a sample of acheson graphite from 0 C. to 800 C

Determinations have been made of both the thermal and the electrical conductivities of a sample of Acheson graphite over the temperature-range from 0°C. to 800°C. The thermal conductivity K is found to decrease from a value of 0.40 unit at 0°C. to 0.16 at 800°C., the rate of decrease being greater at lower temperatures. The electrical conductivity σ has at 0°C. a value of 1218 Ω-1.-cm-1., which increases to a maximum value of 1518 at 450°C. and decreases to 1444 at 800°C. The corresponding Lorenz function Kσ-1T-1 has a value of 121×10-8 at 0°C., which is more than 200 times the value indicated by the electronic theory and possessed by most well-conducting metals. With increase in temperature the value of the Lorenz function decreases rapidly, its value being given by the equation Kσ-1T-1=0.0294T-1.8. Thus the Wiedemann-Franz-Lorenz law does not hold for the present sample of graphite, but is replaced by the equation Kσ-1T0.8=a constant. The power to which the absolute temperature is raised is different, as well as the constant value of the expression.

Experiments with high velocity positive ions VI—The disintegration of carbon, nitrogen, and oxygen by deuterons

1—The use of transmutation data to establish a “corrected mass scale” has made it important to measure with higher precision, nuclear reaction energies. Using the improved methods described in the preceding paper we have therefore reinvestigated the disintegration of carbon, nitrogen, and oxygen by deuterons. Several new groups of particles have been discovered and all the reaction energies determined to within about 0.1 million volts. The new results have been used to correct Bethe’s mass scale and to check the energy balance in the process of positron emission from radio-nitrogen. 2—The Disintegration of Carbon by Deuterons A target of Acheson graphite was bombarded by 2 μA of deuterons of 560 kv energy. The geometry of the apparatus was such that disintegration particles making an angle of 90° ± 6° with the direction of the incident deuterons could enter the counter. The particles were recorded by the double counter described in our paper V and the absorption curve of fig. 1 was obtained, showing the curve obtained by the counters biased to record α-particles and particles of proton ionization respectively.

Thermal Conductivity of Acheson Graphite

Thermal conductivity of Acheson graphite is reported for the temperature range −150°C to +700°C. Cylindrical blocks of the material were placed above and below a flat electric heater and lateral losses balanced out by auxiliary coils wound on the surface of the sample. The results show a continual decrease in thermal conductivity with temperature over the entire range. The law, k/aC=A/T+B, proposed by Bidwell for certain other materials is found to hold accurately for graphite.