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排序方式: 共有1371条查询结果,搜索用时 15 毫秒
51.
Yelim Song Fumio Kawamura Takashi Taniguchi Kiyoshi Shimamura Naoki Ohashi 《Journal of the American Ceramic Society》2018,101(11):4876-4879
In this study, we investigated the Al–Sn flux system and its growth conditions to obtain AlN single crystals. AlN single crystals of a size of 50 μm were successfully grown using an Al–Sn melt under nitrogen gas pressure. The growable region of the AlN crystals was established using a pressure‐temperature diagram. The required nitrogen gas pressure for the growth of the AlN crystals was found to decrease with increasing temperature, and AlN was grown at 0.1 MPa nitrogen pressure above 1300°C. By investigating the AlN yield with various Al concentrations, we confirmed that the Al component in the Al–Sn melt facilitated nitrogen dissolution. Finally, scanning electron microscopy analysis showed that the obtained AlN particles showed good morphology. 相似文献
52.
Wu-Bian Tian Hideki KitaHideki Hyuga Naoki Kondo 《Journal of the European Ceramic Society》2012,32(1):149-156
SiC ceramics were successfully joined by Al infiltrated TiC tapes at 900-1100 °C for 0.5-2 h in vacuum. Phase constituents, microstructure and mechanical strength of the prepared SiC joints were characterized. The prepared SiC joints display dense interlayer and crack-free interface. The interlayer primarily consists of TiC and Al phases, together with small amount of TiAl3 and trace of Al4C3. With increasing the joining temperature or time, the interface layer either thickens or grows to multiple layers. The bending strengths of the SiC joints are higher than 190 MPa as bonded at present conditions, and are closely related with the property of interface and interlayer. 相似文献
53.
High‐strength regenerated cellulose fibers spun from 1‐butyl‐3‐methylimidazolium chloride solutions 下载免费PDF全文
High‐performance regenerated cellulose fibers were prepared from cellulose/1‐butyl‐3‐methylimidazolium chloride (BMIMCl) solutions via dry‐jet wet spinning. The spinnability of the solution was initially evaluated using the maximum winding speed of the solution spinning line under various ambient temperatures and relative humidities in the air gap. The subsequent spinning trials were conducted under various air gap conditions in a water coagulation bath. It was found that low temperature and low relative humidity in the air gap were important to obtain fibers with high tensile strength at a high draw ratio. From a 10 wt % cellulose/BMIMCl solution, regenerated fibers with tensile strength up to 886 MPa were prepared below 22 °C and relative humidity of 50%. High strengthening was also strongly linked with the fixation effect on fibers during washing and drying processes. Furthermore, an effective attempt to prepare higher performance fibers was conducted from a higher polymer concentration solution using a high molecular weight dissolving pulp. Eventually, fibers with a tensile strength of ~1 GPa and Young's modulus over 35 GPa were prepared. These tensile properties were ranked at the highest level for regenerated cellulose fibers prepared by an ionic liquid–based process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45551. 相似文献
54.
Low-resistivity indium tin oxide [ITO] film was successfully deposited on oxygen plasma-treated polyethylene terephthalate [PET] surfaces at room temperature. X-ray diffraction [XRD] measurements demonstrated that the film deposited on the PET surface that had not been treated with oxygen plasma had an amorphous structure. In contrast, after the low-power oxygen plasma treatment of the PET surface, the ITO film deposited on the PET surface had a poly-crystalline structure due to interactions between electric dipoles on the PET surface and electric dipoles in the ITO film. The minimum resistivity of the poly-crystalline ITO was about 3.6 times lower than that of the amorphous ITO film. In addition, we found that the resistivity of ITO film is proportional to the intensity of the (400) line in the film's XRD spectra. 相似文献
55.
Yoshikazu Suzuki Héctor A. Calderón Naoki Kondo Tatsuki Ohji 《Journal of the American Ceramic Society》2000,83(6):1346-1350
The in situ formation of magnetoplumbite-type (M-type) hexaferrites within a 3Y-TZP matrix was examined for the La2 O3 –ZnO–Fe2 O3 and BaO–Fe2 O3 systems. The formation of barium hexaferrite (Ba-M) was rapid enough at a temperature of 1300°C for 2 h to result in a uniform dispersion of fine Ba-M particles in a tetragonal zirconia polycrystal (TZP) matrix. However, the formation of lanthanum-substituted hexaferrite (La-M) was rather sluggish, despite the existence of a charge-compensating divalent oxide. The 3Y-TZP/20-wt%-BaFe12 O19 in situ composite possessed good magnetic properties, as well as moderately good mechanical properties. 相似文献
56.
Minako Nagamori Taro Shimonosono Soichiro Sameshima Yoshihiro Hirata Naoki Matsunaga Yoshio Sakka 《Journal of the American Ceramic Society》2009,92(S1):S117-S121
A thin film (60 μm thick) of a gadolinium-doped ceria (GDC) electrolyte was prepared by the doctor blade method. This film was laminated with freeze-dried 42 vol% NiO–58 vol% GDC mixed powder and pressed uniaxially or isostatically under a pressure of 294 MPa. This laminate was cosintered at 1100 °–1500 °C in air for 4–12 h. The laminate warped because of the difference in the shrinkage of the electrolyte and electrode during the sintering. A higher shrinkage was measured for the electrode at 1100 °–1200 °C and for the electrolyte at 1300 °–1500 °C. The increase of the thickness of anode was effective in decreasing the warp and in increasing the density of the laminated composite. The maximum electric power density with a SrRuO3 cathode using 3 vol% H2 O-containing H2 fuel was 100 mW/cm2 at 600 °C and 380 mW/cm2 at 800 °C, respectively, for the anode-supported GDC electrolyte with 30 μm thickness. 相似文献
57.
In Situ Measurement of Bridging Stresses in Toughened Silicon Nitride Using Raman Microprobe Spectroscopy 总被引:1,自引:0,他引:1
Giuseppe Pezzotti Naoki Muraki Naoki Maeda Kouji Satou Toshihiko Nishida 《Journal of the American Ceramic Society》1999,82(5):1249-1256
Bridging stresses that result both from elastic tractions and frictional interlocking in the wake of an advancing crack have been evaluated quantitatively via in situ Raman microprobe spectroscopy in a toughened Si3 N4 polycrystal. Crack opening displacement (COD) profiles of bridged cracks also have been measured quantitatively via scanning electron microscopy to substantiate the piezospectroscopic determination of microscopic stresses via Raman spectroscopy. The highest spatial resolution of the stress measurement in the Raman apparatus was 1 µm, as dictated by the optical lens that was used to focus the laser on the sample. Measurements of the bridging stresses were performed both at fixed sites (as a function of the applied load) and along the profile behind the crack tip (under a constant load). Rather high stress values (i.e., 0.4-1.1 GPa) were measured that corresponded with unbroken ligaments that bridged the crack faces in elastic fashion, whereas frictional sites were typically under a lower tensile stress (0.1-0.5 GPa). Mapping the near-tip COD profile and the bridging stresses at the (normal) critical load for catastrophic fracture enabled us to calculate the crack-tip toughness and to explain the rising R -curve behavior of the material. From a comparison with conventional fracture-mechanics data, a self-consistent view of the mechanics that govern the toughening behavior of the Si3 N4 polycrystal could be obtained. In particular, crack bridging is proven to be, by far, the most important mechanism that contributes to the toughening of polycrystalline Si3 N4 materials. 相似文献
58.
Polystyrene–clay hybrids (PSCHs) were prepared by melt blending a styrene vinyloxazoline copolymer with organophilic clay. In the PSCHs, the silicate layers of the clay were delaminated and dispersed homogeneously to the nanometer level. The moduli of the PSCHs were higher than that of the PS copolymer. For example, the tensile modulus of the PSCH with 5 wt % clay was 1.4 times higher compared to that of the PS copolymer. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3359–3364, 1999 相似文献
59.
Naoki Dohi Yukimasa Matsuda Norihiro Itano Kazuhiro Shimizu Kimio Mineka Wa Yoshinorika Wase 《加拿大化工杂志》1999,77(5):786-792
Mixing in a boil-off mechanically stirred tank reactor with multiple impellers was examined. Power consumption and gas hold-up were measured in boiling water in a 0.2 m i.d. stirred tank reactor with three four-pitched blade downflow disk turbines. Vapour was generated from both the immersed ring heater and the impellers. At low vapour generation rates, vapour was mainly generated from the impellers rather than from the heater, whereas nucleation occurred at the heater instead of the impeller at higher vapour generation rates. The mechanical power consumption decreased due to vapour generation. The change in boiling-to-non-boiling mechanical power ratio with varying impeller rotational speed and boiling rate was complicated and not monotonous except at higher impeller speeds and boiling rates. The gas hold-ups increased with increasing vapour generation rate but were rather small as compared to those in cold gas dispersing systems. Empirical correlations for power consumption and gas hold-up in boiling liquids were developed using the present experimental data. 相似文献
60.
Naoki Yashiro Tomohiro Usui Koichi Kikuta 《Journal of the European Ceramic Society》2010,30(10):2093-2098
The application of an inkjet printing process for fabricating solid oxide fuel cell (SOFC) cathodes was investigated. Stably-dispersed LSCF–GDC inks were prepared by ball milling, and the composition was easily controlled by the preparation process. Fabrication of an LSCF–GDC layer was successfully carried out by depositing dots and the thickness was easily controlled by repeating printing process. A planar SOFC single cell with a double-layered cathode (comprised of a paste painted cathode layer and an inkjet printed interlayer) achieved a maximum power density of 0.71 W/cm2 at 600 °C. This is the preliminary work for fabricating the cathode layer of a SOFC single cell via inkjet printing. 相似文献