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1.
Yasuhiro Kodera Takeshi Yamamoto Naoki Toyofuku Manshi Ohyanagi Zuhair A. Munir 《Journal of Materials Science》2006,41(3):727-732
The ordering of stacking-disordered silicon carbide prepared from the elements by high energy ball milling was investigated
during sintering. A sharp increase in density in the temperature region 1700–1800°C was associated with a decrease in the
disorder. Samples which had low disorder density showed a more continuous sintering behavior with temperature. Highly dense
(up to 99% relative density) SiC can be obtained at 1900°C under a pressure of 70 MPa with no hold time. Similar results were
observed for structurally disordered carbon with 10 at% of boron. The sintering behavior exhibited an abrupt density increase
in the narrow temperature region of 1450–1600°C and was associated with disorder-order transformation. 相似文献
2.
Masaharu Nagayama Tsutomu Ikeda Tetsuya Ishiwata Norikazu Tamura Manshi Ohyanagi 《Journal of Materials Synthesis and Processing》2001,9(3):153-163
In the present paper, by using a mathematical model for self-propagating high-temperature synthesis, we reveal the three-dimensional structure of so-called spin combustion wave on the inside of cylindrical sample. It is shown that an isothermal surface of regular spin combustion wave has some wings of which number is the same as that of reaction spots on the cylindrical surface and that the isothermal surface with helical wings rotates down with time. Because of this propagating pattern, in this paper, we adopt the more suitable term helical wave. We also obtain the following existence conditions of a helical wave: If physical parameters are set so that a pulsating wave exists stably for the one-dimensional problem, then a helical wave takes the place of a pulsating wave when the radius of cylindrical sample becomes large. 相似文献
3.
Dariusz Kata Kenshiro Shirai Manshi Ohyanagi Zuhair A. Munir 《Journal of the American Ceramic Society》2001,84(4):726-732
The synthesis of solid solutions of AlN–SiC was investigated through the combustion reaction between Si3 N4 , aluminum, and carbon powders and nitrogen gas at pressures ranging from 0.1 to 6.0 MPa. The combustion reaction was initiated locally and then the wave front propagated spontaneously, passing through the cylindrical bed containing the loose powder. In the presence of Si3 N4 as a reactant, it was feasible to synthesize solid solutions at an ambient pressure (0.1 MPa). The relationship between nitrogen pressure and full-width at half-maximum of the (110) peak of the product showed that lower pressures produced more-homogeneous solid solutions. Some aspects of formation of the AlN–SiC solid solutions were discussed with special emphasis on the influence of nitrogen pressure and reactant stoichiometry. 相似文献
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Manshi Ohyanagi Hiroyuki Nishide Koichi Suenaga Eishun Tsuchida 《Polymer Bulletin》1990,23(6):637-642
Summary Oxygen-permselectivity through polyorganosiloxanes with carboxyl group on the side chain is discussed in terms of the differences between the O2, N2 diffusion coefficients or their solubility coefficients. The oxygen-selectivity increases from 2 to 5 with the increase in the carboxyl component of the side chain. Especially the selectivity in the diffusion coefficient is found to more contribute to the oxygenpermselectivity in comparison with that of the solubility coefficient. But the permeation coefficient decreases with the permselectivity.This work was partially supported by a Grand-in-Aid from the Ministry of Education, Science and Culture, Japan. 相似文献
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Levashov E. A. Kharlamov E. I. Kudryashov A. E. Rogachev A. S. Ohyanagi Manshi Koizumi Mitsue Hosomi Satoru 《Journal of Materials Synthesis and Processing》1999,7(1):23-33
The method of Thermoreactive Electrospark Surface Strengthening (TRESS) is presented in this work. Thus the process of coating formation becomes a less energy consuming one as compared to the basic technology of the electrospark alloying. The additional heat of the chemical reaction of the synthesis final products formation on the substrate contribute to the increase of thickness and continuity of the coating, to the diminution of the inner tension due to the smoother concentration gradients through the coating thickness. The opportunities of TRESS method are exposed with the example of the FGM wear- and heat-resistant coating formation on the base of NiAl, TiAl. FGM diamond containing coatings production by the said method is presented. Optimal conditions and technological parameters for diamond containing coatings deposition is found. The masstransfer kinetics, the coating structure and properties were studied. 相似文献
8.
Reactive Synthesis and Phase Stability Investigations in the Aluminum Nitride–Silicon Carbide System
Ellen M. Carrillo-Heian Hongyong Xue Manshi Ohyanagi Zuhair A. Munir 《Journal of the American Ceramic Society》2000,83(5):1103-1107
The effect of AlN on the structure formation of SiC was investigated. SiC was synthesized in the presence of AlN under vacuum at 1500°C, and the result was cubic SiC. The synthesis of AlN–SiC composites through the reaction Si3 N4 + 4Al + 3C = 3SiC + 4AlN was also investigated and compared with synthesis via field-activated self-propagating combustion (FASHS). Reactants were heated in a vacuum furnace at temperatures ranging from 1130° to 1650°C. Below 1650°C, the reaction is not complete and at this temperature the product phases are AlN and cubic SiC. At 1650°C, the product contained an outer layer which contained β-SiC only and an inner region which contained AlN and cubic SiC. 2H-SiC and AlN composites synthesized via field-activated self-propagating combustion were annealed at 1700°C under vacuum. The AlN dissociated and evaporated and the 2H-SiC transformed to the cubic β phase. Reasons for the differences in products of furnace heating and FASHS are discussed. 相似文献
9.
Influence of Synthesis Temperature on the Defect Structure of Boron Carbide: Experimental and Modeling Studies 总被引:1,自引:0,他引:1
Umberto Anselmi-Tamburini Zuhair A. Munir Yasuhiro Kodera Takahito Imai Manshi Ohyanagi 《Journal of the American Ceramic Society》2005,88(6):1382-1387
Boron carbide (B4 C) was synthesized from the elements at temperatures ranging from 1300° to 2100°C using the spark plasma synthesis method. Significant densification commenced at about 1500°C and was accompanied by a corresponding decrease in the defect structure of this carbide. Changes in the X-ray diffraction patterns were in agreement with predictions of simulation studies based on the presence of twins. Transmission electron microscopy observations were consistent with the experimental observations and the modeling predictions. 相似文献
10.
Hiroyuki Ohyanagi Yoshihiko Wakamatsu Yusuke Nakashima Yusuke Nojima Hisao Ishibuchi 《Artificial Life and Robotics》2009,14(3):414-417
The iterated prisoner’s dilemma (IPD) game has frequently been used to examine the evolution of cooperative behavior among
agents. When the effect of representation schemes of IPD game strategies was examined, the same representation scheme was
usually assigned to all agents. That is, in the literature, a population of homogeneous agents was usually used in computational
experiments. In this article, we focus on a slightly different situation where every agent does not necessarily use the same
representation scheme. That is, a population can be a mixture of heterogeneous agents with different representation schemes.
In computational experiments, we used binary strings of different lengths (i.e., three-bit and five-bit strings) to represent
IPD game strategies. We examined the evolution of cooperative behavior among heterogeneous agents in comparison with the case
of homogeneous ones for the standard IPD game with typical payoff values of 0, 1, 3, and 5. Experimental results showed that
the evolution of cooperative behavior was slowed down by the use of heterogeneous agents. It was also demonstrated that a
faster evolution of cooperative behavior is achieved among majority agents than among minority ones in a heterogeneous population. 相似文献