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154. Morphology of aggregates—II. Shape and bulkiness factors of carbon black aggregates from electron microscopy
232
ABSTRACTS
152. Study of the microstructure of carbon blacks. J. B. Donnet and J. Schultz (&ole Su@ieure de Chimie, Mulhouse, France). The oxidation of a thermal black either by silver bichromate in sulphuric medium or by a solution of nitric acid leads to some samples ofoxidized carbon blacks which permit separate study of the inside and the outside of the particle. The study by electron microscopy, by X-ray diffraction, and by thermal treatment pointed out that the external layer of the particle is made of well organized crystallites, parallel to the surface, and contains an important closed porosity; the central part has a lower degree of organization. 153. High resolution electron microscopy of small crystallite carbons. L. L. Ban, W. M. Hess and F. J. Eckert (Columbian Carbon Company, Princeton, New Jersv). High resolution electron microscopy was employed to study microstructural variations in a number of small crystallite carbons which included carbon blacks, chars, cokes and pyrolized polymers. Images of crystallites were obtained using both dark field diffracted beam and phase contrast electron microscopy. Variations in crystallite size (L,) and orientation could be readily determined. Point resolution better than IOA was obtained in dark field and the interplaner spacing of 3.4A was imaged by means of phase contrast for a heat treated (3OOO’C) ISAF carbon black. 154. Morphology of aggregates-II. electron microscopy.
Shape and bulkiness factors of carbon black aggregates from
A. I. Medalia and F. A. Heckman (Cabot Corporation, Cambridge, Massachusetts). Carbon black exists as primary aggregates composed of primary particles fused together. We have measured the size, anisometry and bulkiness of these primary aggregates by electron microscopy. These parameters, which define “structure,” show a wide spread within a given sample. Weight-average parameters are calculated with the aid of a relation between projected area and number of particles per aggregate, based on computer-simulated floes. As expected, the average values for all three parameters are high for acetylene black and low for thermal black. Furnace blacks give intermediate values, with aggregate size being the predominant parameter related to “structure”. 155. Microscopic characterization of layer stacking in pyrolytic graphite. E. R. Stover (General Electric Company, Re-Entry Systems Department, Philadelphia, Pennsylvania). Polishing with Ha + 0, flames at T.Ul~.Ce> 1700°C removes pitting impurities, etches cracks, and provides translucent thin sections perpendicular to the atomic layers. In electron transmission basal-plane tilt-boundary fringes define distances of parallel stacking between void-free C-direction tilt boundaries, which are etched by combustion but not by ion bombardment, The growth-cone nucleating “whiskers” are revealed as conical spirals. Upon graphitization coherently diffracting bands 2 50 A thick appear parallel to layers. After N 3500°C annealing coplanar crystals with a variety of basal twist or translation boundaries are revealed in transmission and by surface etching, and suggest mechanisms of crystal growth. 156. Optical and electron microscopy of carbonaceous materials.* R. D. Reiswig, L. S. Levinson and T. D. Baker (Los Alamos Scientijc Laboratory, University of California, Los A system of preparation of specimens of carbonaceous materials for optical and electron microscopy is described. Two innovations contained in this system are the use of hydrogen ion bombardment as a means of etching for optical microscopy and the use of masks to facilitate the etching of specimens impregnated with and mounted in epoxy resin. The interpretation of some microstructural features common to graphites is discussed and the use of the term “optical domain” in descriptions of these materials is proposed. Alamos, New Mexico).
l Work
pcrformcd
under
the auspices
of the United
States
Atomic
Energy
Commission.
157. Transmitted light microscopy of graphite.* E. M. Woodruff (Battelle Memorial Institute, Richland, Washington). Preparation of optically transparent thin sections of polycrystalline graphite is described. The technique uses specimens mounted in epoxy resin which are polished flat on one side, remounted in resin, and ground and polished from the opposite side until transparent. Examination of graphite comprised of petroleum coke filler and coal tar pitch binder demonstrates that
ABSTRACTS
152. Study of the microstructure of carbon blacks. J. B. Donnet and J. Schultz (&ole Su@ieure de Chimie, Mulhouse, France). The oxidation of a thermal black either by silver bichromate in sulphuric medium or by a solution of nitric acid leads to some samples ofoxidized carbon blacks which permit separate study of the inside and the outside of the particle. The study by electron microscopy, by X-ray diffraction, and by thermal treatment pointed out that the external layer of the particle is made of well organized crystallites, parallel to the surface, and contains an important closed porosity; the central part has a lower degree of organization. 153. High resolution electron microscopy of small crystallite carbons. L. L. Ban, W. M. Hess and F. J. Eckert (Columbian Carbon Company, Princeton, New Jersv). High resolution electron microscopy was employed to study microstructural variations in a number of small crystallite carbons which included carbon blacks, chars, cokes and pyrolized polymers. Images of crystallites were obtained using both dark field diffracted beam and phase contrast electron microscopy. Variations in crystallite size (L,) and orientation could be readily determined. Point resolution better than IOA was obtained in dark field and the interplaner spacing of 3.4A was imaged by means of phase contrast for a heat treated (3OOO’C) ISAF carbon black. 154. Morphology of aggregates-II. electron microscopy.
Shape and bulkiness factors of carbon black aggregates from
A. I. Medalia and F. A. Heckman (Cabot Corporation, Cambridge, Massachusetts). Carbon black exists as primary aggregates composed of primary particles fused together. We have measured the size, anisometry and bulkiness of these primary aggregates by electron microscopy. These parameters, which define “structure,” show a wide spread within a given sample. Weight-average parameters are calculated with the aid of a relation between projected area and number of particles per aggregate, based on computer-simulated floes. As expected, the average values for all three parameters are high for acetylene black and low for thermal black. Furnace blacks give intermediate values, with aggregate size being the predominant parameter related to “structure”. 155. Microscopic characterization of layer stacking in pyrolytic graphite. E. R. Stover (General Electric Company, Re-Entry Systems Department, Philadelphia, Pennsylvania). Polishing with Ha + 0, flames at T.Ul~.Ce> 1700°C removes pitting impurities, etches cracks, and provides translucent thin sections perpendicular to the atomic layers. In electron transmission basal-plane tilt-boundary fringes define distances of parallel stacking between void-free C-direction tilt boundaries, which are etched by combustion but not by ion bombardment, The growth-cone nucleating “whiskers” are revealed as conical spirals. Upon graphitization coherently diffracting bands 2 50 A thick appear parallel to layers. After N 3500°C annealing coplanar crystals with a variety of basal twist or translation boundaries are revealed in transmission and by surface etching, and suggest mechanisms of crystal growth. 156. Optical and electron microscopy of carbonaceous materials.* R. D. Reiswig, L. S. Levinson and T. D. Baker (Los Alamos Scientijc Laboratory, University of California, Los A system of preparation of specimens of carbonaceous materials for optical and electron microscopy is described. Two innovations contained in this system are the use of hydrogen ion bombardment as a means of etching for optical microscopy and the use of masks to facilitate the etching of specimens impregnated with and mounted in epoxy resin. The interpretation of some microstructural features common to graphites is discussed and the use of the term “optical domain” in descriptions of these materials is proposed. Alamos, New Mexico).
l Work
pcrformcd
under
the auspices
of the United
States
Atomic
Energy
Commission.
157. Transmitted light microscopy of graphite.* E. M. Woodruff (Battelle Memorial Institute, Richland, Washington). Preparation of optically transparent thin sections of polycrystalline graphite is described. The technique uses specimens mounted in epoxy resin which are polished flat on one side, remounted in resin, and ground and polished from the opposite side until transparent. Examination of graphite comprised of petroleum coke filler and coal tar pitch binder demonstrates that