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Kinetics of graphitization of a 1600°C pyrocarbon deposit
ABSTRACTS
343
102. A study of the catalytic graphitization of carbon M. P. Whittaker and H. C. Fritz (Great Lakes Research Corporation, Elizabethton, Tennessee). Structural changes which accompany the catalytic graphitization of carbon have been investigated. Utilizing X-ray diffraction and high temperature microscopy techniques, the effectiveness of various additives in promoting the formation of graphite from a variety of carbon materials of varying degrees of graphitizability is elucidated. 103. The development of mesophase microstructures during pyrolysis of selected coker feedstocks R. J. Price and J. L. White (Gulf General Atomic Company, Sand Diego, California). Polarized light microscopy was used to observe the formation of mesophase microstructures during the pyrolysis of selected coker feedstocks, including a vacuum-reduced crude, an air-blown asphalt, a thermal tar, and gilsonite. These materials developed a range of microstructural components characterized by extinction contour patterns differing widely in anisotropy and contour spacing. 104. Appearance and development of anisotropic mesophase from various carbonaceous materials in early-stage carbonization Y. Sanada, T. Furuta, H. Kimura and H. Honda (National Research Institutefor Pollution and Resources, Kawaguchi-Saitama, Japan). Low temperature carbonization of pitches, reduced crude, synthetic polymers and various rank of coals was studied with polarized-light microscopic methods. The aromaticity of starting materials may play an important role for nucleation and growth of spherical anisotropic mesophase. Appearance and development of anisotropic mesophase are function of heattreatment temperature and residence time for those materials which pass through a fusion stage at the temperaure range from 350 to 500°C. 105. Kinetics of graphitization
of a 1600% pyrocarbon
deposit
(Centre a!eRecherches Paul Pascal, Domaine Universitaire, ;33-Pessac, France). Heattreatment effect of this “semi-hard” carbon is quite original and leads to a material, magnetic and structural properties of which are comparable to those of nuclear graphite. Furthermore starting from a theoretical study we introduce a mathematical form fitting the curves corresponding to stepwise evolutions of the physical properties vs. residence time at HTT. J. Prost and H. Gasparoux
106. Kinetics and graphitization: determination of activation parameter S. Flandrois and A. Tinga (Centre de Recherches Paul Pascal, Domaine Universitaire 33-Talence, France). The kinetics of graphitization (between 1475°C and 2650°C) of a pitch coke has been followed by diamagnetic susceptibility and Hall effect measurements at room temperature. The results show that the Arrhenius law is not obeyed and lead to a critical analysis of previous works. Similar conclusions are obtained for an acetylene black. 107. Microscopic
observation
of graphitization
under high pressure
(Mie University, Honmaru, Marunourhi, Tsu, Mie, Japan). M. Inagaki (Nagoya l!niversity, Furocho, Chikusa-ku, Nagoya, Japan) and K. Kamiya (Mie University, Honmaru, Marunouchi, Tsu, Mie, Japan). Hard carbon grains were heattreated at temperatures between 1100” and 1600°C under 5 kbar. Graphitization of non-graphic carbon was observed microscopically to start at contacts between angular grains of carbon. The area of graphitized part increased with increase in HTT. Large strain due to the local concentration of the compression stress at the contacts can cause the nucleation of graphite and the graphite nucleus thus produced grows into the area where large strains exist. T. Noda
108. The influence of internal stresses on graphitization D. B. Fischbach (Dept. of Mining, Metallurgical and Ceramic Engineering, University of Washington, Seattle). The graphitization kinetics behaviors of powder and solid samples of several pyrolytic carbons have been compared. Sample form had no effect on either graphitization rate or activation energy. Evidently, “long-range” internal stresses, which should be affected by powdering, do not play a significant role. Important differences in the rate and shape of the graphitization vs. time curves for various PCs and for other types of graphitizing carbons must be attributed to influences of short-range stresses and/or microstructure.
343
102. A study of the catalytic graphitization of carbon M. P. Whittaker and H. C. Fritz (Great Lakes Research Corporation, Elizabethton, Tennessee). Structural changes which accompany the catalytic graphitization of carbon have been investigated. Utilizing X-ray diffraction and high temperature microscopy techniques, the effectiveness of various additives in promoting the formation of graphite from a variety of carbon materials of varying degrees of graphitizability is elucidated. 103. The development of mesophase microstructures during pyrolysis of selected coker feedstocks R. J. Price and J. L. White (Gulf General Atomic Company, Sand Diego, California). Polarized light microscopy was used to observe the formation of mesophase microstructures during the pyrolysis of selected coker feedstocks, including a vacuum-reduced crude, an air-blown asphalt, a thermal tar, and gilsonite. These materials developed a range of microstructural components characterized by extinction contour patterns differing widely in anisotropy and contour spacing. 104. Appearance and development of anisotropic mesophase from various carbonaceous materials in early-stage carbonization Y. Sanada, T. Furuta, H. Kimura and H. Honda (National Research Institutefor Pollution and Resources, Kawaguchi-Saitama, Japan). Low temperature carbonization of pitches, reduced crude, synthetic polymers and various rank of coals was studied with polarized-light microscopic methods. The aromaticity of starting materials may play an important role for nucleation and growth of spherical anisotropic mesophase. Appearance and development of anisotropic mesophase are function of heattreatment temperature and residence time for those materials which pass through a fusion stage at the temperaure range from 350 to 500°C. 105. Kinetics of graphitization
of a 1600% pyrocarbon
deposit
(Centre a!eRecherches Paul Pascal, Domaine Universitaire, ;33-Pessac, France). Heattreatment effect of this “semi-hard” carbon is quite original and leads to a material, magnetic and structural properties of which are comparable to those of nuclear graphite. Furthermore starting from a theoretical study we introduce a mathematical form fitting the curves corresponding to stepwise evolutions of the physical properties vs. residence time at HTT. J. Prost and H. Gasparoux
106. Kinetics and graphitization: determination of activation parameter S. Flandrois and A. Tinga (Centre de Recherches Paul Pascal, Domaine Universitaire 33-Talence, France). The kinetics of graphitization (between 1475°C and 2650°C) of a pitch coke has been followed by diamagnetic susceptibility and Hall effect measurements at room temperature. The results show that the Arrhenius law is not obeyed and lead to a critical analysis of previous works. Similar conclusions are obtained for an acetylene black. 107. Microscopic
observation
of graphitization
under high pressure
(Mie University, Honmaru, Marunourhi, Tsu, Mie, Japan). M. Inagaki (Nagoya l!niversity, Furocho, Chikusa-ku, Nagoya, Japan) and K. Kamiya (Mie University, Honmaru, Marunouchi, Tsu, Mie, Japan). Hard carbon grains were heattreated at temperatures between 1100” and 1600°C under 5 kbar. Graphitization of non-graphic carbon was observed microscopically to start at contacts between angular grains of carbon. The area of graphitized part increased with increase in HTT. Large strain due to the local concentration of the compression stress at the contacts can cause the nucleation of graphite and the graphite nucleus thus produced grows into the area where large strains exist. T. Noda
108. The influence of internal stresses on graphitization D. B. Fischbach (Dept. of Mining, Metallurgical and Ceramic Engineering, University of Washington, Seattle). The graphitization kinetics behaviors of powder and solid samples of several pyrolytic carbons have been compared. Sample form had no effect on either graphitization rate or activation energy. Evidently, “long-range” internal stresses, which should be affected by powdering, do not play a significant role. Important differences in the rate and shape of the graphitization vs. time curves for various PCs and for other types of graphitizing carbons must be attributed to influences of short-range stresses and/or microstructure.