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991.
992.
Tatsuo Shikama Tatsuhiko Tanabe Masakazu Fujitsuka Masahiro Kitajima Heitaro Yoshida Ryoji Watanabe 《Metallurgical and Materials Transactions A》1980,11(9):1589-1598
The corrosion behavior of Inconel 617, a candidate for the structural material of heat exchanger in the high temperature gas-cooled
reactor (HTGR), has been investigated at elevated temperatures in the hydrogen base gas mixture (80 pct H2 + 15 pct CO + 5 pct CO2). This gas mixture simulates the reducing gas in the direct steel making system that uses heat from HTGR in Japan. This gas
has relatively high oxidizing and carburizing potentials. In the temperature range of 650 to 1000 °C Inconel 617 oxidized
to form a Cr2O3 scale containing titanium oxide. The activation energy for this process is estimated to be 50 to 60 kcal/mol. The time dependence
of the growth of the surface oxide scale was parabolic. The aluminum in Inconel 617 was internally oxidized. The time dependence
of the internal oxidation was noticed to obey a 0.4 power rate law. Carburization was noticed at 650 and 900 °C. At 900 °C,
carbides containing Si, Ti, and Mo precipitated beneath the oxide scale for gas exposure times up to 200 h. After 200 h, the
formation and growth of the surface scale suppresses carburization. The thermodynamic analysis of gas atmosphere proposed
by Gurry could be applied successfully to the experimental results. Some inconsistency existed mainly because of the scale
formation and direct gas-metal interactions. 相似文献
993.
Retsuo Kawakami Kikuo Tominaga Kenji Okada Takahiro Nouda Takeshi Inaoka Atsushi Takeichi Toshiaki Fukudome Kenichi Murao 《Vacuum》2010,84(12):1393-1397
Etch damage of TiO2 thin films with the anatase phase by capacitively coupled RF Ar plasmas has been investigated. The plasma etching causes a mixed phase of anatase and rutile or the rutile phase. The effect of Ar plasma etching damage on degenerating TiO2 thin films is dependent on gas pressure and etching time. The physical etching effect at a low gas pressure (1.3 Pa) contributes to the degradation: the atomic O concentration at the thin film surface is strongly increased. At a high gas pressure (13-27 Pa) and long etching time (60 min), there are a variety of surface defects or pits, which seem to be similar to those for GaN resulting from synergy effect between particle and UV radiation from the plasmas. For the hydrophilicity, the thin film etched at the high gas pressure and a short etching time (5 min) seems to have no etch damage: its contact angle property is almost similar to that for the as-grown thin film, and is independent of the black light irradiation. This result would probably result from formation of donor-like surface defects such as oxygen vacancy. 相似文献
994.
Seicho Makihira Yuichi Mine Hiroki Nikawa Takahiro Shuto Eduardo Kosaka Masaru Sugiyama Ryuji Hosokawa 《Journal of materials science. Materials in medicine》2010,21(2):647-653
The purpose of the present study was to examine the effect of osteoprotegerin (OPG)-Fc fusion protein immobilized on a titanium surface on the initial differentiation of osteoclast precursor RAW264.7 cells. These cells were cultured on titanium specimens over which OPG-Fc was immobilized. The enhancement of tartrate-resistant acid phosphatase (TRAP) and cathepsin K mRNA expression in RAW264.7 cells exposed to receptor activator of NF-κB ligand (RANKL) stimulation on OPG-Fc-coated titanium was significantly lower than that in RAW264.7 cells exposed to RANKL on titanium specimens without immobilized OPG-Fc (ANOVA, P < 0.01). Preincubation of OPG-Fc-coated titanium, in a medium supplemented with 10% fetal bovine serum at 37°C for two days before the cells were seeded, had no significant effect on the decrease in mRNA expression (ANOVA, P < 0.01). Taken together, these results indicate that OPG-Fc immobilized on a titanium surface blocks the differentiation of RAW264.7 cells induced by RANKL stimulation. 相似文献
995.
A single vortex is excited into nano-size Pb superconducting island structures by a local current injection from a probe tip of a scanning tunneling microscope. For the excitation, a sufficient amount and duration of the pulsed current are required. Injecting the current at peripheral sites is more effective than the center for the vortex excitation. Time-dependent Ginzburg-Landau calculations suggest that a current-induced normal-state area, which can be nucleated by the tunneling current exceeding the critical current and expanded by the Joule heating, reduces the required magnetic field for the vortex penetration and excites a vortex into the islands. 相似文献
996.
Akira Azushima Yoshifumi Nakata Takahiro Toriumi 《Journal of Materials Processing Technology》2010,210(1):110-115
In order to reduce the rolling force and the roll wear, the lubricants have been used in hot rolling of steel. In order to evaluate the tribological behavior at the interface between roll and workpiece in hot steel rolling, it is important to measure the coefficient of friction and examine the effect of the tribological factors on the coefficient of friction. In this paper, the effect of the rolling speed on the coefficient of friction is investigated using the tribo-simulator testing machine for hot rolling developed by the authors. The workpiece used is SPHC. The roll material is SKD11 and the surface roughnesses are 0.05 μm, 0.2 μm and 0.8 μm. The rolling tests are carried out at a temperature of 800 °C during a rolling distance of 400 mm, changing the rolling speed from 15 to 70 m/min. The colza oil is used as a base oil and the emulsion concentrations are 0.1% and 3.0%. The coefficient of friction at an emulsion concentration of 3.0% is independent on the rolling speed. On the other hand, the coefficient of friction at an emulsion concentration of 0.1% decreases with increasing rolling speed in the lower range of rolling speed, but it increases in increasing rolling speed in the higher range of rolling speed. 相似文献
997.
998.
Molybdenum disilicide powders were prepared by heating a mixture of Mo and Si powders with Na metal. The single phases of β-MoSi2 and α-MoSi2 powders were obtained at 873 K and 1073 K, respectively. The preparation temperature of the single phase α-MoSi2 powder was 500 K lower than that of the conventional solid state reaction method using Mo and Si powders. The grain size of both MoSi2 powders was less than 2 μm, and their shape was angular and irregular. 相似文献
999.
Kenji Watanabe Takashi Taniguchi Kenta Miya Yoshitaka Sato Kazuhito Nakamura Takahiro Niiyama Masateru Taniguchi 《Diamond and Related Materials》2011,20(5-6):849-852
Luminous properties of hexagonal boron nitride (hBN) single-crystal powder were studied by cathodoluminescence and photoluminescence spectroscopy. The single crystals grown by a high pressure and high temperature method showed typical excitonic spectra at peak wavelengths of 215, 220, and 227 nm at room temperature. Well-faceted hexagonal shaped single crystals exhibited the dominant 215-nm band. The 220- and 227-nm bands were singly or concurrently observed in the case of irregular-shaped crystal powders, though no discernible difference between the morphologies of crystal powders showing differently superimposed luminous spectral profiles of the 220- and 227-nm bands was observed. However, each band showed different spectral and decay features at 8 K, implying that the origins of the two bands are different. 相似文献
1000.