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Structure of glassy carbon
344
ABSTRACTS
109. Catalytic graphitization of model compound chars D. L. Biederman, H. N. Murty and E. A. Heintz (Airco Speer Research Laboratories, Niagara Falls, New York). The use of metal additives for the catalysis of graphitization of chars prepared by high temperature, high pressure ~rbonization of anthracene, phenanthrene or biphenyl has been investigated, In particular the extent and type of catalysis initiated by aluminum or beryllium has been examined, Quantitative X-ray measurements have been performed and this data is used to show the existence of at least two concurrent mechanisms of graphitization catalysis. Evidence for the preferential attack on the disorganized carbon by the graphitization catalyst has been found. 110. Catalysis of graphitization of boronated commercial carbons D. L. Biederman, Z-I. N. Murty and E. A. Heintz (Airco Speer Research Laborat~~es, Nkgara FalEs, IVY! York). The graphitization kinetics of two boronated petroleum cokes and one boronated mineral coke have been examined. Kinetic data were obtained at temperatures ranging from 1800°C to 2700°C using boron concentrations in the range 0.5 to 5 per cent (wt,.) elemental boron. Apparent energies of activation and pre-exponential factors have been estimated and are compared with those obtained in the absence of boron. A probable mechanism of the graphitization of boronated carbons will be presented. 111. Carbonisation of anthracene and biphenyl under pressures approaching 300 MNmw2 H. Marsh, F. Dachille, J. Melvin, P. L. Walker, Jr., M. Hurley and A. P. Warburton (Un&rGty of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, U.K.). Objectives include estimates of the effect of pressure, up to 300 MNm-*, during carbonisation to 600°C upon graphitisability of the semi-cokes, and of the mechanism of interaction of a non-graphitising material (biphenyl) upon a graphitising material (anthracene) also during carbonisation. Analytical techniques include scanning electron microscopy, mass spectrometry, X-ray diffraction and optical microscopy. Results show that pressure markedly improves ~aphitisability, it permits separation i.e., prevents coalescence of mesophase spheres, and suggest that there is no chemical interaction of biphenyf with anthracene molecules. There is a physical interaction involving growth of the mesophase. 112. Structure of glassy carbon M. M. Biswall, P. Bihuniak and R. H. Bragg (Lawrence Berketey Laboratory, Department of Materials Science, U~i~~s~~ of Ca~~~~~a, Berkeley, ~a~z~rn~). The structure of various glassy carbons has been investigated using various diffraction techniques. It was found that: (1) the time at temperature must be specified in order to describe the state of glassy carbon; (2) most of the published lattice parameters and crystallite size estimates are incorrect due to specimen absorption effects; and (3) the nature of the bonding in glassy carbon is still unknown. 113. X-Ray small-angle scattering of glassy carbon R. Perret and W. Ruland (ii&on Garbide Europeans Research Assoc~~es, S.A. Rue Patti de Gamo~ ‘)5, ii80 Br~ell~, Belgium). The characteristic size parameters and the volume fraction of micropores have been determined in a series of glassy carbons of various origin. A unique relationship between pore size and heattreatment temperature has been found which is similar to that observed for carbon fibers and which suggests a similarity in the microstructure of these materials. 114. An X-ray study of the structure of a heattreated glassy carbon S. Ergun, R. R. Schehl and M. Berman (U. S. Bureau of adds, P~tsburgh, P~~yl~a~~a). The structure of a heattreated glassy carbon has been examined by studying the X-ray intensity profiles at small and large angles. The profiles of the (hk0) reflections alone do not permit distinguishing whether the sample is made up of small crystallites or of large but defective domains. More detailed information is derived from the atomic radial distribution function and small-angle scattering intensities. 115. Structural changes caused by air activation of a petroleum base activated carbon W. B. NickIes (Witco C~rn~ca~ Corp~ut~n, Oakland, Newness). Air activations carried out between 800“ and 1200°F produced transition pores {5~-50 A radii) which are not produced to the same degree by high temperature steam activations, The pore volumes increase much faster than surface area changes. Temperatures below 950°F experienced virtually no external burning before a 30 per cent loss in weight. Lower temperatures gave rise to macropores nearer to the 1000 A radius size range whereas the higher temperatures produced macropores closer to the 100 A radius sizes.
ABSTRACTS
109. Catalytic graphitization of model compound chars D. L. Biederman, H. N. Murty and E. A. Heintz (Airco Speer Research Laboratories, Niagara Falls, New York). The use of metal additives for the catalysis of graphitization of chars prepared by high temperature, high pressure ~rbonization of anthracene, phenanthrene or biphenyl has been investigated, In particular the extent and type of catalysis initiated by aluminum or beryllium has been examined, Quantitative X-ray measurements have been performed and this data is used to show the existence of at least two concurrent mechanisms of graphitization catalysis. Evidence for the preferential attack on the disorganized carbon by the graphitization catalyst has been found. 110. Catalysis of graphitization of boronated commercial carbons D. L. Biederman, Z-I. N. Murty and E. A. Heintz (Airco Speer Research Laborat~~es, Nkgara FalEs, IVY! York). The graphitization kinetics of two boronated petroleum cokes and one boronated mineral coke have been examined. Kinetic data were obtained at temperatures ranging from 1800°C to 2700°C using boron concentrations in the range 0.5 to 5 per cent (wt,.) elemental boron. Apparent energies of activation and pre-exponential factors have been estimated and are compared with those obtained in the absence of boron. A probable mechanism of the graphitization of boronated carbons will be presented. 111. Carbonisation of anthracene and biphenyl under pressures approaching 300 MNmw2 H. Marsh, F. Dachille, J. Melvin, P. L. Walker, Jr., M. Hurley and A. P. Warburton (Un&rGty of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, U.K.). Objectives include estimates of the effect of pressure, up to 300 MNm-*, during carbonisation to 600°C upon graphitisability of the semi-cokes, and of the mechanism of interaction of a non-graphitising material (biphenyl) upon a graphitising material (anthracene) also during carbonisation. Analytical techniques include scanning electron microscopy, mass spectrometry, X-ray diffraction and optical microscopy. Results show that pressure markedly improves ~aphitisability, it permits separation i.e., prevents coalescence of mesophase spheres, and suggest that there is no chemical interaction of biphenyf with anthracene molecules. There is a physical interaction involving growth of the mesophase. 112. Structure of glassy carbon M. M. Biswall, P. Bihuniak and R. H. Bragg (Lawrence Berketey Laboratory, Department of Materials Science, U~i~~s~~ of Ca~~~~~a, Berkeley, ~a~z~rn~). The structure of various glassy carbons has been investigated using various diffraction techniques. It was found that: (1) the time at temperature must be specified in order to describe the state of glassy carbon; (2) most of the published lattice parameters and crystallite size estimates are incorrect due to specimen absorption effects; and (3) the nature of the bonding in glassy carbon is still unknown. 113. X-Ray small-angle scattering of glassy carbon R. Perret and W. Ruland (ii&on Garbide Europeans Research Assoc~~es, S.A. Rue Patti de Gamo~ ‘)5, ii80 Br~ell~, Belgium). The characteristic size parameters and the volume fraction of micropores have been determined in a series of glassy carbons of various origin. A unique relationship between pore size and heattreatment temperature has been found which is similar to that observed for carbon fibers and which suggests a similarity in the microstructure of these materials. 114. An X-ray study of the structure of a heattreated glassy carbon S. Ergun, R. R. Schehl and M. Berman (U. S. Bureau of adds, P~tsburgh, P~~yl~a~~a). The structure of a heattreated glassy carbon has been examined by studying the X-ray intensity profiles at small and large angles. The profiles of the (hk0) reflections alone do not permit distinguishing whether the sample is made up of small crystallites or of large but defective domains. More detailed information is derived from the atomic radial distribution function and small-angle scattering intensities. 115. Structural changes caused by air activation of a petroleum base activated carbon W. B. NickIes (Witco C~rn~ca~ Corp~ut~n, Oakland, Newness). Air activations carried out between 800“ and 1200°F produced transition pores {5~-50 A radii) which are not produced to the same degree by high temperature steam activations, The pore volumes increase much faster than surface area changes. Temperatures below 950°F experienced virtually no external burning before a 30 per cent loss in weight. Lower temperatures gave rise to macropores nearer to the 1000 A radius size range whereas the higher temperatures produced macropores closer to the 100 A radius sizes.