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Association of nuclei during carbon black formation in thermal systems
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Abstracts
magnetothermal oscillations have been observed in pyrolytic graphite. Four de-Haas van Alphen frequencies were detected. The results point towards a correlation between one of the minority frequencies and the difference of the two majority frequencies.
chamber with a focused continuous CO, laser beam. Temperature was measured by pyrometers with < O.Olset reaction time. A pressure range of 0~0016-6~0atm was covered, and the carbon solid-liquid-gas triple point was located at 3780 + 30°K at 0.19 + 0.02 atm.
12. Change of electronic properties of neutron irradiated pyrocarbon under thermal annealing A. S. Kotosonov (V/O “Soyuzuglerod,” Mowcow, 111123, U.S.S.R.). No short abstract submitted.
tThis work reflects research supported under U.S. Air Force Space and Missile Systems Organization (SAMSO) Contract No. FO4701-74-C-0075 and the Atomic Energy Commission.
13. Model of structure for interstitial carbon in graphite J. Conard and H. Estrade (C.R.S.O.C.I.-CNRS, 4.5045 Orleans, France). This paper discusses interstitial carbon grafted 1.2 A above the center of aromatic ring. For this point defect an electronic structure is proposed which uses overlap of sp,, px, py, orbitals of carbon and II electrons of aromatic ring. It is shown that graphitic situation increases stabilization. The carbon is negatively charged giving induced ionic bond with opposite aromatic plane. This model would explain creation of a varying gap, Hall anomaly and other properties of graphitizable carbons. 14. Association of nuclei during carbon black formationin thermal systems G. Prado and J. Lahaye (Center De Recherches SW La Physic0 -Chimie Des Surfaces Solides, Mulhouse, France). The liquid droplets, precursors of carbon black particles formed during thermal decomposition of benzene can collide and stick together. A computer simulation of these particle associations points out that they account well for the distortion of the size distribution curves during the particle growth step, as experimentally observed previously. 15. Behavior of diamond under positive ion bombardment and CO, laser irradiation at very high power densityt A. G. Whittaker (The Aerospace Corporation, El Segundo, CA). A brief experimental study was made of the transformation of diamond to graphite or chaoite by a 20-kV 02+ ion beam. Small slabs of diamond with (100) and (111) polished faces were used. Transformation to graphite appeared to depend mainly on crystal imperfections, but transformation to chaoite occurred only on the (111) face and depended upon the current density of the ion beam. Small craters in the (111) face produced by a CO, laser at very high power density were examined. It was found that graphite and chaoite were formed simultaneously.
17. Macroscopic model for the interlayer thermal expans-
ion of a series of pyrocarbons G. Fug, P. Delhaes and H. Gasparoux (Centre de Recherches Paul Pascal, 33405Talence , France). Thermal expansion of a series of pyrocarbon samples, heat treated at dierent H.T.T., has been measured between 20 and 2400 K. The theoretical analysis of these data, by the means of a macroscopic model adapted to non cristalline anisotropic solids behaviour, leads to the interpretation of some peculiar phenomena and to the prediction of specific heat of these pyrocarbon. 18. Triple point pressureof carbon as determinedby laser heatingt D. M. Haaland (Sandia Laboratories, Albuquerque, NM 87115). The triple point pressure of carbon has been accurately determined using a high pressure gas autoclave with Nd:YAG cw laser heating. The minimum melt pressure for samples of pyrolytic graphite in both helium and argon has been found to be 107 + 2 atmospheres. This minimum melt pressure has been identified as the triple point pressure of carbon. tThis work supported by the U.S. Energy Research and Development Administration. 19. Magnetic field dependenceof the specific heat peak at
0.6-OPK in soft carbonst A. S. Vagh and S. Mrozowski (State University New York at Bufalo and Ball State University, Muncie, IN). The dependence of the relatively broader specific heat peak in neutron irradiated graphite (5Ohr dose) and of the sharper one in the soft carbon (HTT 1250°C) on the magnetic field were investigated. In both cases the specific heat increases with the field in the whole range of temperature 0.4-4.5”K and the position of the peak shifts slightly to higher temperature. The reasons for this behavior is discussed. tSupported by the National Science Foundation.
20. Low temperature anomalies in specific heat of soft tThis work was supported by the U.S. Air Force Under Space carbons? and Missile Systems Organization Contract No. FO4701-74-C-0075. 16. Carbon solid-liquid-vapor triple point and the behav-
ior of superheatedliquid carbon? A. G. Whittaker and P. L. Kintner (The Aerospace Corporation, El Segundo, CA) and L. S. Nelson and N. Richardson (Sandia Laboratory, Albuquerque, NM). The total vapor pressure of carbon was determined by heating pyrolytic graphite in a controlled pressure
S. Mrozowski and A. S. Vagh (State University New York at Buffalo and Ball State University, Muncie, IN). With an improved apparatus the shape of the specific heat peak at around 060~7°K was investigated for two series of variously heattreated soft carbons (coal tar pitch base and petroleum base) and for polycrystalline graphite tSupported by the National Science Foundation.
Abstracts
magnetothermal oscillations have been observed in pyrolytic graphite. Four de-Haas van Alphen frequencies were detected. The results point towards a correlation between one of the minority frequencies and the difference of the two majority frequencies.
chamber with a focused continuous CO, laser beam. Temperature was measured by pyrometers with < O.Olset reaction time. A pressure range of 0~0016-6~0atm was covered, and the carbon solid-liquid-gas triple point was located at 3780 + 30°K at 0.19 + 0.02 atm.
12. Change of electronic properties of neutron irradiated pyrocarbon under thermal annealing A. S. Kotosonov (V/O “Soyuzuglerod,” Mowcow, 111123, U.S.S.R.). No short abstract submitted.
tThis work reflects research supported under U.S. Air Force Space and Missile Systems Organization (SAMSO) Contract No. FO4701-74-C-0075 and the Atomic Energy Commission.
13. Model of structure for interstitial carbon in graphite J. Conard and H. Estrade (C.R.S.O.C.I.-CNRS, 4.5045 Orleans, France). This paper discusses interstitial carbon grafted 1.2 A above the center of aromatic ring. For this point defect an electronic structure is proposed which uses overlap of sp,, px, py, orbitals of carbon and II electrons of aromatic ring. It is shown that graphitic situation increases stabilization. The carbon is negatively charged giving induced ionic bond with opposite aromatic plane. This model would explain creation of a varying gap, Hall anomaly and other properties of graphitizable carbons. 14. Association of nuclei during carbon black formationin thermal systems G. Prado and J. Lahaye (Center De Recherches SW La Physic0 -Chimie Des Surfaces Solides, Mulhouse, France). The liquid droplets, precursors of carbon black particles formed during thermal decomposition of benzene can collide and stick together. A computer simulation of these particle associations points out that they account well for the distortion of the size distribution curves during the particle growth step, as experimentally observed previously. 15. Behavior of diamond under positive ion bombardment and CO, laser irradiation at very high power densityt A. G. Whittaker (The Aerospace Corporation, El Segundo, CA). A brief experimental study was made of the transformation of diamond to graphite or chaoite by a 20-kV 02+ ion beam. Small slabs of diamond with (100) and (111) polished faces were used. Transformation to graphite appeared to depend mainly on crystal imperfections, but transformation to chaoite occurred only on the (111) face and depended upon the current density of the ion beam. Small craters in the (111) face produced by a CO, laser at very high power density were examined. It was found that graphite and chaoite were formed simultaneously.
17. Macroscopic model for the interlayer thermal expans-
ion of a series of pyrocarbons G. Fug, P. Delhaes and H. Gasparoux (Centre de Recherches Paul Pascal, 33405Talence , France). Thermal expansion of a series of pyrocarbon samples, heat treated at dierent H.T.T., has been measured between 20 and 2400 K. The theoretical analysis of these data, by the means of a macroscopic model adapted to non cristalline anisotropic solids behaviour, leads to the interpretation of some peculiar phenomena and to the prediction of specific heat of these pyrocarbon. 18. Triple point pressureof carbon as determinedby laser heatingt D. M. Haaland (Sandia Laboratories, Albuquerque, NM 87115). The triple point pressure of carbon has been accurately determined using a high pressure gas autoclave with Nd:YAG cw laser heating. The minimum melt pressure for samples of pyrolytic graphite in both helium and argon has been found to be 107 + 2 atmospheres. This minimum melt pressure has been identified as the triple point pressure of carbon. tThis work supported by the U.S. Energy Research and Development Administration. 19. Magnetic field dependenceof the specific heat peak at
0.6-OPK in soft carbonst A. S. Vagh and S. Mrozowski (State University New York at Bufalo and Ball State University, Muncie, IN). The dependence of the relatively broader specific heat peak in neutron irradiated graphite (5Ohr dose) and of the sharper one in the soft carbon (HTT 1250°C) on the magnetic field were investigated. In both cases the specific heat increases with the field in the whole range of temperature 0.4-4.5”K and the position of the peak shifts slightly to higher temperature. The reasons for this behavior is discussed. tSupported by the National Science Foundation.
20. Low temperature anomalies in specific heat of soft tThis work was supported by the U.S. Air Force Under Space carbons? and Missile Systems Organization Contract No. FO4701-74-C-0075. 16. Carbon solid-liquid-vapor triple point and the behav-
ior of superheatedliquid carbon? A. G. Whittaker and P. L. Kintner (The Aerospace Corporation, El Segundo, CA) and L. S. Nelson and N. Richardson (Sandia Laboratory, Albuquerque, NM). The total vapor pressure of carbon was determined by heating pyrolytic graphite in a controlled pressure
S. Mrozowski and A. S. Vagh (State University New York at Buffalo and Ball State University, Muncie, IN). With an improved apparatus the shape of the specific heat peak at around 060~7°K was investigated for two series of variously heattreated soft carbons (coal tar pitch base and petroleum base) and for polycrystalline graphite tSupported by the National Science Foundation.