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1.
Microstructure and mechanical behaviour of 3Y-TZP/Mo nanocomposites possessing a novel interpenetrated intragranular microstructure 总被引:2,自引:0,他引:2
Yttria stabilized tetragonal zirconia polycrystal (Y-TZP)/0-100 vol % molybdenum (Mo) composites were fabricated by hot-pressing a mixture of Y-TZP powder containing 3 mol % yttria (Y2O3) and a fine Mo powder in vacuum. This composite system possessed a novel microstructural feature composed of an interpenetrated intragranular nanostructure, in which either nanometer sized Mo particles or equivalent sized zirconia (ZrO2) particles located within the ZrO2 grains or Mo grains, respectively. The strength and toughness were both greatly enhanced with increasing Mo content for the 3Y-TZP/Mo composites thus breaking through the strength-toughness tradeoff relation in transformation toughened ZrO2 and its composite materials. They exhibited a maximum strength of 2100 MPa and a toughness of 11.4 MPa·m1/2 for the composite containing 70 vol % Mo. These simultaneous improvements in strength and toughness were determined to be the result of a decrease in flaw size associated with the interpenetrated intragranular nanostructure, and a stress shielding effect created in the crack tip by the elongated Mo polycrystals bridging the crack tip in addition to the stress induced phase transformation. 相似文献
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Takashi Yamazaki Yoichi Takino Ryosuke Matsuoka Susumu Ito 《Electrical Engineering in Japan》1993,113(8):26-36
According to the recent analysis results of temporary ac overvoltage in the ac system connected with a frequency converter station, large-magnitude over-voltages were confirmed to occur under some special system conditions. Most of the station insulators currently used cannot withstand such overvoltages according to an evaluation based on the data obtained earlier. The necessity of tests to be done to evaluate such performance more accurately was recognized. Both power frequency and switching impulse overvoltage flashover tests were made on contaminated insulators by the method well simulating the natural wetting condition. Switching impulse flashover voltage with the waveshape having a long wavefront time of 2 ms can be well correlated with the flashover voltage characteristics of temporary ac overvoltage. Higher flashover voltage characteristics were obtained by a clean fog test method compared with those obtained by equivalent fog test method. 相似文献
4.
Narayanaswami C. Kamijoh N. Raghunath M. Inoue T. Cipolla T. Sanford J. Schlig E. Venkiteswaran S. Guniguntala D. Kulkarni V. Yamazaki K. 《Computer》2002,35(1):33-41
Nearly four years in development, the IBM Linux watch contains a complete computer system that runs Linux, displays X11 graphics, and has wireless connectivity. The system fits in a case that could pass as a slightly unusual analog timepiece with a somewhat odd shape and an extraordinarily brilliant face. The developers have created two versions of the watch, one with an organic light-emitting diode display and the other with a liquid crystal display. Still considered a research prototype, the watch already runs some personal information management applications, and it can communicate with PCs, PDAs, and other wireless-enabled devices, viewing condensed e-mail and directly receiving pager-like messages. Eventually, users will be able to access various Internet-based services, such as up-to-the-minute information about weather, traffic conditions, the stock market, and sports 相似文献
5.
Nakamura K. Oguri T. Atsumo T. Takada M. Ikemoto A. Suzuki H. Nishigori T. Yamazaki T. 《Solid-State Circuits, IEEE Journal of》1992,27(11):1504-1510
The authors report a 4 M word×1 b/1 M word×4 b BiCMOS SRAM that can be metal mask programmed as either a 6-ns access time for an ECL 100 K I/O interface to an 8-ns access time for a 3.3-V TTL I/O interface. Die size is 18.87 mm×8.77 mm. Memory cell size is 5.8 μm×3.2 μm. In order to achieve such high-speed address access times the following technologies were developed: (1) a BiCMOS level converter that directly connects the ECL signal level to the CMOS level; (2) a high-speed BiCMOS circuit with low threshold voltage nMOSFETs; (3) a design method for determining the optimum number of decoder gate stages and the optimum size of gate transistors; (4) high-speed bipolar sensing circuits used at 3.3-V supply voltage; and (5) 0.55-μm BiCMOS process technology with a triple-well structure 相似文献
6.
An attempt was made to deposit carbon films by electrolysis of a water-ethylene glycol solution. Carbon plate and an n-type silicon substrate were dipped in the solution and a high d.c. potential was negatively applied on the silicon substrate. Some deposits were observed in the region between the boiling point curve and the line approximately 50 °C below and parallel to the boiling point, when electrolysis was carried out at 1 kV for 6 h. For higher potentials of 1.4–2.0 kV and longer electrolysis of 12 h, some samples showed a broad X-ray diffraction peak and Raman peaks, corresponding to graphitic carbon. 相似文献
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Takiguchi Y. Nakayama M. Kubota M. Yamazaki J. 《Broadcasting, IEEE Transactions on》1998,44(1):123-130
Two kinds of TV cameras have been developed that are capable of showing the wavelengths of ultraviolet, infrared, and visible light by means of a false color method. One is sensitive to wavelengths from 250 to 650 nm (ultraviolet to yellow). It can simulate the color vision of the honey bee and other insects, reproducing the nectar guide of a flower or displaying the sex of a cabbage white moth, which is indistinguishable to the naked eye. The other is sensitive to a wider wavelength of 250 to 1,050 nm (ultraviolet to near infrared). According to the filter selected, it obtains not only visual images of invisible light information but also pictures same as those from an ordinary color camera. These TV cameras can be applied in many fields, including science, art, medicine, and industry 相似文献
9.
A potential barrier model along the grain boundaries in ultrathin tin dioxide (SnO2) gas sensors is presented. It is assumed that the negatively charged oxygens are adsorbed only on the grain boundaries. The
potential barrier depth is expressed as functions of grain size, donor concentration and surface coverage of adsorbed oxygen
ions at the boundaries. A direct consequence is that the conduction electrons are effectively confined in a grain when the
film thickness becomes smaller than a critical value. This indicates a drastic increase in resistivity with decreasing film
thickness in air, and thus an occurrence of an extremely high gas sensitivity. 相似文献
10.
Nakamura K. Kuhara S. Kimura T. Takada M. Suzuki H. Yoshida H. Yamazaki T. 《Solid-State Circuits, IEEE Journal of》1994,29(11):1317-1322
This 512 Kw×8 b×3 way synchronous BiCMOS SRAM uses a 2-stage wave-pipeline scheme, a PLL self-timing generator and a 0.4-μm BiCMOS process to achieve 220 MHz fully-random read/write operations with a GTL I/O interface. Newly developed circuit technologies include: 1) a zig-zag double word-line scheme, 2) a centered bit-line load layout scheme, and 3) a phase-locked-loop (PLL) with a multistage-tapped ring oscillator which generates a clock cycle proportional pulse (CCPP) and a clock edge lookahead pulse (CELP) 相似文献