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排序方式: 共有3223条查询结果,搜索用时 484 毫秒
61.
Keiichi Tomishige Shogo Kanazawa Motoki Sato Kenji Ikushima Kimio Kunimori 《Catalysis Letters》2002,84(1-2):69-74
Pt(0.3)/Ni(10)/Al2O3, prepared by a sequential impregnation method, exhibited a more excellent performance in methane reforming with CO2 and O2 in terms of the catalytic activity and the temperature profile of the catalyst bed than Pt(0.3) + Ni(10)/Al2O3 prepared by a coimpregnation method, Ni(10)/Al2O3, Pt(0.3)/Al2O3, and Pt(10)/Al2O3. It is thought that this is because the surface Pt atoms on Ni catalyst can contribute to the enhancement of the catalyst reducibility. 相似文献
62.
Hikota Akimoto Osamu Ishikawa Gong-Hun Oh Masahito Nakagawa Tohru Hata Takao Kodama 《Journal of Low Temperature Physics》1991,82(5-6):295-316
Spin dynamics of3He-4He dilute solution have been studied in the collisionless regime by NMR methods. In cw NMR experiments, we observed spin waves in a magnetic field gradient. The frequency difference between the first mode and the others obeyed a two-thirds power law in the strength of the field gradient. By using a pulsed NMR method, nonlinear spin dynamics were studied. We observed the large amplitude spin waves after an rf pulse. The frequency of each spin-wave mode depended on the tipping angle. By using the parameter determined in the present experiment, the numerical calculated results based on Leggett-Rice theory are in good agreement with the results of the pulsed NMR experiments. 相似文献
63.
Yumi Fukuda Koichi Harada Maki Yonetsu Ariane K. Albessard Yasushi Hattori Kenji Essaki Yasuhiro Goto Tomohiro Suetsuna 《Journal of the American Ceramic Society》2021,104(12):6563-6571
When reaction-bonded silicon nitride containing MgO/Y2O3 additives is sintered at three different temperatures to form sintered reaction-bonded silicon nitride (SRBSN), the thermal conductivity increases with sintering temperature. The β-Si3N4 (silicon nitride) crystals of SRBSN ceramics were synthesized and characterized to investigate the relation between the crystal structure and the lattice oxygen content. The hot-gas extraction measurement result and the crystal structure obtained using Rietveld analysis suggested that the unit cell size of the β-Si3N4 crystal increases with the decrease in the lattice oxygen content. This result is reasonable considering that the lattice oxygen with the smaller covalent radius substitutes nitrogen with the larger one in the β-Si3N4 crystals. The lattice oxygen content decreased with increasing sintering temperature which also correlated with increase in thermal conductivity. Moreover, it is noteworthy from the viewpoint that it may be possible to apply the lattice constant analysis for the nondestructive and simple measurement of the lattice oxygen content that deteriorates the thermal conductivity of the β-Si3N4 ceramics. 相似文献
64.
Toshiji Mukai T. G. Nieh Yoshihito Kawamura Akihisa Inoue Kenji Higashi 《Intermetallics》2002,10(11-12)
Mechanical deformation of Pd40Ni40P20 was characterized in compression over a wide strain rate range (3.3×10−5 to 2×103 s−1) at room temperature. The compression sample fractured with a shear plane inclined 42 degree with respect to the loading axis, in contrast to 56 degree for the case of tension. This suggests the yielding of the material deviates from the classical von Mises yield criterion, but follows the Mohr-Coulomb yield criterion. Fracture stress as well as strain was found to decrease with increasing applied strain rate. The compressive stress (1.74 GPa) was also found to be higher than the tensile fracture stress at a quasi-static strain rate. Close examination of the stress–strain curves revealed that localized shear might have occurred at a compressive stress of about 1.4 GPa, much lower than the “apparent” yield stress of 1.74 GPa. However, the stress of 1.4 GPa for shear band initiation is almost the same as the fracture stress measured at a dynamic strain rate of 5×102 s−1. These results suggested that the fracture of a bulk metallic glass is sensitive to the applied loading rate. 相似文献
65.
Setsuo?TakakiEmail author Toshihiro?Tsuchiyama Koichi?Nakashima Hideyuki?Hidaka Kenji?Kawasaki Yuichi?Futamura 《Metals and Materials International》2004,10(6):533-539
The microstructure development during plastic deformation was reviewed for iron and steel which were subjected to cold rolling
or mechanical milling (MM) treatment, and the change in strengthening mechanism caused by the severe plastic deformation (SPD)
was also discussed in terms of ultra grain refinement behavior. The microstructure of cold-rolled iron is characterized by
a typical dislocation cell structure, where the strength can be explained by dislocation strengthening. It was confirmed that
the increase in dislocation density by cold working is limited at 1016m−2, which means the maximum hardness obtained by dislocation strengthening is HV3.7 GPa. However, the iron is abnormally work-hardened
over the maximum dislocation strengthening by SPD of MM because of the ultra grain refinement caused by the SPD. In addition,
impurity of carbon plays an important role in such grain refinement: the carbon addition leads to the formation of nano-crystallized
structure in iron. 相似文献
66.
Amorphous Al50Ta60 alloy powders have been synthesized by mechanical alloying (MA) from elemental powders of aluminium and tantalum, and mechanical disordering (MD) from crystalline intermetallic compound powders of AlTa respectively using the rod milling technique. The mechanically alloyed and the mechanically disordered alloy powders were characterized by X-ray diffraction, scanning electron microscopy, electron probe microanalysis, transmission electron microscopy, differential thermal analysis, differential scanning calorimetry and chemical analysis. The results have shown that the crystal-to amorphous transformation in the MD process occurs through one stage, while the crystallineto-amorphous formation in the MA process occurs through three stages. At the early and intermediate stages of the MA time, heating the alloy powders to 700 K leads to the formation of an amorphous phase by a solid-state amorphizing reaction. At the final stage of the MA time, the amorphous phase is crystallized through a single sharp exothermic peak. Contrary to this, amorphous alloy powders produced by MD are crystallized through two broad exothermic peaks. 相似文献
67.
Mitsuhiro Shikida Yosuke Niimi Tatsuya Hasegawa Tomoaki Sugino Satoshi Hamaoka Kenji Fukuzawa 《Microsystem Technologies》2015,21(3):661-668
Mechanical strengthening of a Si cantilever by applying KOH wet etching was investigated. Two kinds of Si cantilever specimens having the different crystallographic orientations of the sidewall surfaces, i.e., Si{100} and Si{110}, were fabricated from the same SOI wafer by a Bosch process. The typical height and pitch of the scalloping formed on the sidewall were 248 and 917 nm, respectively. A 50 % KOH (40 °C) chemical wet etching was applied to increase the fracture stress of the Si cantilever. The fracture stress in the both of Si{100} and Si{110} cantilevers increased with the advance of the etching. The obtained maximum fracture stress in Si{100} and Si{110} were 4.2 and 3.7 GPa, respectively. Sidewall surface of the cantilever was analyzed to investigate the mechanical strengthening of Si cantilever by wet etching. The etched surface crystalline was analyzed by the transmission electron microscope (TEM), and confirmed that the thickness of the affected flow layer was less than 10 nm from the obtained TEM image. Then the change of the surface roughness by the KOH etching was analyzed by the atomic force microscope. The surface was smoothened with the advance of the KOH etching. The roughness value of Ra in Si{100} and Si{110} decreased to 12.1 and 37.7 nm, respectively. 相似文献
68.
69.
Yoshihisa Shinya Kenji Kamiya Tomoyuki Toyoda Yasumi Endo Nelly Soudakova Hirofumi Kondo 《Journal of the Society for Information Display》2009,17(4):331-336
Abstract— The display used in current cell phones has an air gap between the cover glass and the liquid‐crystal‐display (LCD) module to prevent the LCD glass from being damaged. Reflections at the boundaries of the air gap cause a reduction in the LCD luminance and contrast. To address this problem, a newly proposed LCD structure has been investigated. The “Super View Resin (SVR),” a transparent elastic resin which improves the shock resistance and visibility of the LCD, has been developed. Filling the air gap between the cover glass and LCD module with a refractive‐index‐matching resin solves the light‐reflection problem inherent in the use of a reinforced cover‐glass lens. Moreover, the elastic filler works as a damper, reducing any external shock, which prevents not only the cover glass and LCD module from being damaged, but also the glass from being shattered when it is broken. 相似文献
70.
Ken-ichi Kumagai Kenji Kawano Isao Watanabe Kusuo Nishiyama Kanetada Nagamine 《Journal of Superconductivity》1994,7(1):63-67
Muon spin rotation (
+SR) measurement provides clear evidence of the antiferromagnetic order of Cu moments below 35 K for La2–x
Ba
x
CuO4 and below 15 K for La2–x
Sr
x
CuO4 in the narrow range ofx where the high-T
c
superconductivity (SC) is suppressed remarkably. The results suggest that the change of the electronic state coupled with the lattice instability is relevant to the local suppression of SC and freezing of spin fluctuations of the Cu moment. 相似文献