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43. Glassy carbon graphitization: density changes
Abstracts Mutterphase prinzipietl gut gee&net zu sein. Bei einer vergleichenden Betrachtung einer Reihe von Wachstumsformen, die in Systemen unterschiedlicher Zusammensetzung und unter verschiedenartigen luBeren Bedingungen entstanden sind, ergeben sich einige bemerkenswerte ~bereinstimmungen im ~istallinen Habitus. 43. Glassy carbon graphitfzation:density changes D. B. Fischbach and M. E. Rorabaugh (Dept. ofMining Metallurgical and Ceramic Engineering, FB-10, University of Washington, Seattle, Wash. 98195, U.S.A.).
Densities of several varieties of glassy carbon were measured in a ~nzene~tetrabromoethane gradient column after heat treatment in the range 800-3000°C. Density decreases occur primarily as a result of volume expansion which depends on material source, sample size, heating rate and temperature. This expansion is attributed to deformation under pressure generated within the closed porosity by desorption and continued pyrolysis. 44. Studies oa the catalytic graphitization of petroleum cokes S. Jasienko, and L. Wajzer (Znstytut Chemii i Technologii Nafty i Wegla Politechniki Wroclawskiej, ul. ~da~ska 7/9, SO-344 Wro~law, Poland). 45. Aspekte zur Charakterisierungdes strukturelien Au-
fbaues von R&en E. Koberstein und M. Voll (Degussa Wolfgang, physikalisch-shenzische Fors~hungsabte~lung).
und
anorganisch -chemische
46. Disclinationstructuresin the carbonaceousmesopbese J. L,. White and J. E. Zimmer (The Aerospace Corporation, P.O. Box 92951, Los Angeles, Calif. 90009, U.S.A.). Disclinations are inherent to the lamelliform
morphology of the carbonaceous mesophase and its heat-treated fossils, including coke and graphite. Optical and electron microscopy have been used to define disclination structures in coarse and deformed mesophase under various conditions of heat-treatment. 47. Characterization of oriented voids in pyrolyticgraphite S. Bose and R. H. Bragg (materials and molecular Research Divisiori, Lawrence 3e~eley Laborato~ and Department of Materials Science and Engineering, University of California, Berkeley, Calif. 94120, U.S.A.). The
orientation dependence of the small angle scattering by pyrolytic graphite has been investigated. The intensity can be interpreted in terms of the scattering by voids whose shape is oblate ellipsoids of revolution with semi-major and semi-minor axes of a and b respectively. The scattering in the Guinier region is equivalent to that of a dilute dispersion of oriented “Guinier spheres” whose radius is H\l$(a2sin2 y + b2cosZ~)“2, where y is the angle between b and the scattering vector h. 48. Explanation of “unorganizedcarbon” in gtassycarbon S. Bose and R. H. Bragg (Materials and Molecular Research Division, Lawrence Berkeley Laboratory and Department of Materials Science and Engineering, University of California, Berkeley, Calif 94720, U.S.A.).
291
X-ray diffraction studies of glassy carbon (CC) in which the collimation of the incident and diffracted beams, and the specimen thickness were varied indicate that: (1) small angle scattering is the most prominent feature of the diffraction pattern and is at least two orders of magnitude stronger than the 002 interference maximum; (2) the excess intensity below the 002 maximum, sometimes attributed to “unorganized carbon” or “misaligned single layers,” is merely the high angle part of the small angle scattering; and (3) the data obtained in reflection are shifted significantly towards smaller values of 28 whereas the line profiles obtained in transmission are relatively undistorted. 49. Informations dCduitesde I’analysede la diffusion des rayons X aux petits angles dans I’btudedes carbones D. Tchoubar et C. H. Pons (Centre de Recherche sur les Solides & O~anisation C~stalline i~pa~aits, C.N.R.S., Rue de la Ferollerie. 4.5045 Orl~ans-C~dex, France). By
taking into account the instrumental aberrations in the experimental small angle X-ray scattering curves, it has been possible to refine the description of the porosity in the desordered carbons. The relation between the structural evolution of the layer stakings and the modification of the porosity, during the ~aphitization, is illustrated for a sample of petroleum coke. 50. A microscopicexamination of coke structure using an automatic image analysis system J. W. Patrick, M. J. Sims and A. E. Stacey (British Carbonization Research Association, Cheste~eld, Derbyshire, S42 6JS, England). Cokes prepared on both the
large scale and on the laboratory scale were examined by reflected light microscopy and the structure was analyzed by use of a computerized image analysis system. Determinations were made of the total porosity, the mean size and size dis~bution (based on ho~zontal chords) of pores and pore-walls, the pore perimeter and the number of pores. For the laboratory-prepared cokes correlations were found between the coke tensile strength and several of the structural parrameters but these relations were less clearly defined for the cokes prepared on the commercial scale. 51. Einsatz der quantitativen Bldanalyse zur Charakterisierung von G&t und Fyrokoblenstoff K. Koizlik, W. Delle, H. Hoven und H. Uhlenbruck, (Institut fiir Reaktorwerkstofe der Kemforschungsanlage Jiilich, D-517 Jiilich, Postfuch 1913). The porosity of
reactor graphites and pyrocarbons in~uences decisively their irradiation behaviour and fission product retention during operation in High Temperature Reactors (HTR’s). For the evaluation of total number, total volume and size distribution of macropores for the reason of quality control an automatic, quantitative image analyser is used. The measured variables correlated with the mentioned material parameters are defined, the mathematical operations for the correction of measured values and for the calculation of material parameters are discussed, Finally, first experimental and mathematical results are presented in the case of pyrocarbon.
Densities of several varieties of glassy carbon were measured in a ~nzene~tetrabromoethane gradient column after heat treatment in the range 800-3000°C. Density decreases occur primarily as a result of volume expansion which depends on material source, sample size, heating rate and temperature. This expansion is attributed to deformation under pressure generated within the closed porosity by desorption and continued pyrolysis. 44. Studies oa the catalytic graphitization of petroleum cokes S. Jasienko, and L. Wajzer (Znstytut Chemii i Technologii Nafty i Wegla Politechniki Wroclawskiej, ul. ~da~ska 7/9, SO-344 Wro~law, Poland). 45. Aspekte zur Charakterisierungdes strukturelien Au-
fbaues von R&en E. Koberstein und M. Voll (Degussa Wolfgang, physikalisch-shenzische Fors~hungsabte~lung).
und
anorganisch -chemische
46. Disclinationstructuresin the carbonaceousmesopbese J. L,. White and J. E. Zimmer (The Aerospace Corporation, P.O. Box 92951, Los Angeles, Calif. 90009, U.S.A.). Disclinations are inherent to the lamelliform
morphology of the carbonaceous mesophase and its heat-treated fossils, including coke and graphite. Optical and electron microscopy have been used to define disclination structures in coarse and deformed mesophase under various conditions of heat-treatment. 47. Characterization of oriented voids in pyrolyticgraphite S. Bose and R. H. Bragg (materials and molecular Research Divisiori, Lawrence 3e~eley Laborato~ and Department of Materials Science and Engineering, University of California, Berkeley, Calif. 94120, U.S.A.). The
orientation dependence of the small angle scattering by pyrolytic graphite has been investigated. The intensity can be interpreted in terms of the scattering by voids whose shape is oblate ellipsoids of revolution with semi-major and semi-minor axes of a and b respectively. The scattering in the Guinier region is equivalent to that of a dilute dispersion of oriented “Guinier spheres” whose radius is H\l$(a2sin2 y + b2cosZ~)“2, where y is the angle between b and the scattering vector h. 48. Explanation of “unorganizedcarbon” in gtassycarbon S. Bose and R. H. Bragg (Materials and Molecular Research Division, Lawrence Berkeley Laboratory and Department of Materials Science and Engineering, University of California, Berkeley, Calif 94720, U.S.A.).
291
X-ray diffraction studies of glassy carbon (CC) in which the collimation of the incident and diffracted beams, and the specimen thickness were varied indicate that: (1) small angle scattering is the most prominent feature of the diffraction pattern and is at least two orders of magnitude stronger than the 002 interference maximum; (2) the excess intensity below the 002 maximum, sometimes attributed to “unorganized carbon” or “misaligned single layers,” is merely the high angle part of the small angle scattering; and (3) the data obtained in reflection are shifted significantly towards smaller values of 28 whereas the line profiles obtained in transmission are relatively undistorted. 49. Informations dCduitesde I’analysede la diffusion des rayons X aux petits angles dans I’btudedes carbones D. Tchoubar et C. H. Pons (Centre de Recherche sur les Solides & O~anisation C~stalline i~pa~aits, C.N.R.S., Rue de la Ferollerie. 4.5045 Orl~ans-C~dex, France). By
taking into account the instrumental aberrations in the experimental small angle X-ray scattering curves, it has been possible to refine the description of the porosity in the desordered carbons. The relation between the structural evolution of the layer stakings and the modification of the porosity, during the ~aphitization, is illustrated for a sample of petroleum coke. 50. A microscopicexamination of coke structure using an automatic image analysis system J. W. Patrick, M. J. Sims and A. E. Stacey (British Carbonization Research Association, Cheste~eld, Derbyshire, S42 6JS, England). Cokes prepared on both the
large scale and on the laboratory scale were examined by reflected light microscopy and the structure was analyzed by use of a computerized image analysis system. Determinations were made of the total porosity, the mean size and size dis~bution (based on ho~zontal chords) of pores and pore-walls, the pore perimeter and the number of pores. For the laboratory-prepared cokes correlations were found between the coke tensile strength and several of the structural parrameters but these relations were less clearly defined for the cokes prepared on the commercial scale. 51. Einsatz der quantitativen Bldanalyse zur Charakterisierung von G&t und Fyrokoblenstoff K. Koizlik, W. Delle, H. Hoven und H. Uhlenbruck, (Institut fiir Reaktorwerkstofe der Kemforschungsanlage Jiilich, D-517 Jiilich, Postfuch 1913). The porosity of
reactor graphites and pyrocarbons in~uences decisively their irradiation behaviour and fission product retention during operation in High Temperature Reactors (HTR’s). For the evaluation of total number, total volume and size distribution of macropores for the reason of quality control an automatic, quantitative image analyser is used. The measured variables correlated with the mentioned material parameters are defined, the mathematical operations for the correction of measured values and for the calculation of material parameters are discussed, Finally, first experimental and mathematical results are presented in the case of pyrocarbon.