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排序方式: 共有145条查询结果,搜索用时 31 毫秒
41.
42.
Dmitri V. Malakhov Xing Jun Liu Ikuo Ohnuma Kiyohito Ishida 《Journal of Phase Equilibria and Diffusion》2000,21(6):514-520
A thermodynamic assessment of the Bi-Sn-Zn ternary system was carried out by considering the experimental data including the
phase equilibria and thermodynamic properties on the basis of the CALPHAD method. A set of optimized thermodynamic parameters
has been obtained, which leads to a very good fit between calculation and experiments. In particular, the thermodynamic calculations
in the Sn-rich portion are presented in view of the recent progress in Pb-free solder alloys. 相似文献
43.
Tongsai Jamnongkan Ryo Shirota Sathish K. Sukumaran Masataka Sugimoto Kiyohito Koyama 《Polymer Engineering and Science》2014,54(9):1969-1975
Recently, interest in nonwoven mats composed of fibers manufactured by drawing polymer solutions or melts with suspended nanoparticles has been growing due to exciting opportunities for use in biomedical applications. Poly(vinyl alcohol) (PVA), due to its biocompatibility, and zinc oxide (ZnO), due its antibacterial activity, present one interesting combination for the manufacture of nonwoven fiber mats for potential use as wound dressings. Therefore, we have investigated the electrospinning of aqueous PVA solutions with suspended ZnO nanoparticles. ZnO nanoparticles of three different diameters (20, 70, and 100 nm) were used in the study. Interestingly, we found that increasing the diameter of suspended ZnO nanoparticles was accompanied by a decrease in the diameter of the electrospun fibers. Fourier transform infrared spectroscopy indicated that the ZnO nanoparticles were merely suspended in the aqueous PVA solution without any chemical bonding between the ZnO nanoparticles and the PVA chains. Shear rheometry of the suspensions indicated that, over the relevant range of shear rates, all of the samples exhibited essentially Newtonian behavior. However, the viscosity increased with a decrease in the diameter of the ZnO nanoparticles. We suggest that the effect of the nanoparticles on the diameter of the electrospun fibers is through their effect on the viscosity of the suspension from which the fibers are drawn. Finally, as was expected, increasing the electric field strength led to a gradual decrease in the diameter of the electrospun fibers. POLYM. ENG. SCI., 54:1969–1975, 2014. © 2013 Society of Plastics Engineers 相似文献
44.
It is well known that the magnetic properties such as the Curie temperature TmagC and the mean magnetic moment β of ordered compounds have different values from those of the disordered solutions. For instance, both Tcmag and β of the Ni3 Pt (L12) and NiPt (L10) and Tcmag of the CoPt (L10) and CoPt3 (L12) ordered compounds are strongly depressed due to the ordering compared with those of the metastable disordered Ni-Pt and Co-Pt alloys. On the other hand, the γ-FeNi3(L12) and the α-FeCo (B2) ordered compounds have higher Tcmag and β values comparing with the disordered solution phases, γ (A1) and α (A2), respectively. In consequence, the stability of the ordered phase is depressed or enhanced due to the interaction between the chemical and magnetic ordering caused by the decrease or increase of Tcmag and β values. The purpose of this study is to investigate the effect of the interaction between the chemical and the magnetic ordering on the phase equilibria in the Fe-X(X=Al, Co, Ni, Rh, Si) binary systems.The Gibbs energy of the α(A2), γ(A1) and liquid phases is described by a sub-regular solution approximatior. The ordering contribution to the Gibbs energy ,ΔGmorder, and deviations of magnetic properties, ΔTcmag and Δβ, of the ordered compounds, FeAl(B2), Fe3 Al (D03), FeCo (B2), FeRh (B2), FeSi (B2), Fe3 Si (D03) and FeNi3 (L12) is introduced by the split compound energy formalism. Effect of the interaction between the chemical ordering, B2, D03 and L12 and the magnetic ordering on the phase equilibria will be discussed according to the calculated phase diagrams of the Fe-X binary systems. 相似文献
45.
Yoshikazu Takaku Komei Makino Keita Watanabe Ikuo Ohnuma Ryosuke Kainuma Yasushi Yamada Yuji Yagi Ikuo Nakagawa Takashi Atsumi Kiyohito Ishida 《Journal of Electronic Materials》2009,38(1):54-60
The Zn-Al(-Cu) eutectic alloys (melting point 381°C) are candidates for use as Pb-free high-temperature solders as a substitute
for Pb-based solders, which are suitable for severe working environments such as the engine room of hybrid vehicles equipped
with an inverter system as well as a heat engine. In this study, the interfacial reaction between Zn-Al(-Cu) alloys and the
Ni substrate during soldering, aging, and thermal cycling was investigated. Semiconductor chips and Ni substrates were soldered
with Zn-Al(-Cu) alloys at various temperatures under a nitrogen atmosphere. The soldered assemblies were then heat-treated
at 200°C and 300°C to examine the microstructural evolution at the soldered interface. The effect of severe thermal cycles
between −40°C and 250°C in air on the microstructure and fracture behavior at the solder joint was investigated. Even after
a 1000-cycle test, the thickness of the Al3Ni2 layer formed at the interface between the Zn-Al-based solder and the Ni substrate, which is responsible for the damage of
the soldered assemblies, was quite small. 相似文献
46.
Oxidation-Induced Microstructural Change of Si-Ti-C-O Fibers 总被引:2,自引:0,他引:2
Ken-ichi Kakimoto Toshio Shimoo Kiyohito Okamura 《Journal of the American Ceramic Society》1998,81(2):409-412
Two types of Si-Ti-C-O fibers STC(6HS) and STC(6H), with different C/Si molar ratios of 0.99 and 1.65, respectively, have been subjected to oxidation tests at high temperatures between 1000° and 1500°C. Both fibers showed different mass gain during the oxidation tests. In the unoxidized region, there was no change in the chemical composition. For STC(6HS), coarse ß-SiC grains were formed throughout the region, while the grain coarsening in STC(6H) was restricted to the vicinity of the film/fiber interface. In this paper, the influence of free carbon on the oxidation-induced microstructural change of Si-Ti-C-O fibers is discussed. 相似文献
47.
Ouji Y Yoshida-Terakura A Hayashi Y Maeda I Kawase M Yamato E Miyazaki J Yagi K 《Journal of Bioscience and Bioengineering》2002,94(1):81-83
In search of an efficient nonviral vector, polyethyleneimine (PEI)-based vectors were examined. In general, the transfection efficiency of nonviral vectors is suppressed by serum. Here we show that PEI based vectors, particularly, the chitosan hexamer-PEI vector, could perform efficient gene transfection into intestinal epithelial cells (IEC-6) in the presence of serum. The conjugation order of the two polymers with a plasmid (first, chitosan hexamer; second, PEI) was found to be an important factor in enhancing transfection efficiency. 相似文献
48.
Nineteen fluorescent pH standards or pI markers ranging pH 3.64-10.12 were developed for use in capillary isoelectric focusing using laser-induced fluorescence detection. Tetra- to tridecapeptides containing one cysteine residue were designed to focus sharply at their respective isoelectric points by including amino acids that contain charged side chains, the pKa values of which are close to the corresponding pI values. An iodoacetylated derivative of tetramethylrhodamine was coupled to the thiol group of cysteine to yield fluorescent pI markers. The pI values of the labeled peptides were precisely determined after isoelectric focusing on polyacrylamide gel slabs by direct measurement of the pH of the focused bands. The markers were subjected to capillary isoelectric focusing for 10-15 min in coated capillaries under conditions of low electroosmosis and were detected by means of a scanning laser-induced fluorescence detector down to a level of subpicomolar range. The markers permitted the calibration of a wide-range pH gradient formed in a capillary by fluorescence detection for the first time and should facilitate the development of highly sensitive analytical methods based on a combination of capillary isoelectric focusing and laser-induced fluorescence detection. 相似文献
49.
Two-phase equilibria between the ferromagnetic fcc and the paramagnetic fcc phase from 800 ℃ to 900 ℃ in the Co-rich region have been detected by the diffusion couple technique. Two phase separation region of the fcc has been confirmed along the Curie temperature. The phase equilibria including the present results and the thermodynamic data of the Co-Cr system reported in the literature were analyzed on the basis of the thermodynamic evaluation. A set of thermodynarnic values for the liquid, fcc, hcp, bcc, sigma phases was obtained. The calculated phase equilibria were in good agreement with most of the experimental data. 相似文献
50.
It is known that pure Co undergoes martensitic transformation from γ phase (fcc) to ε phase (hcp) by the movement of a/6<112> Shockley partial dislocations at around 400 ℃, however, there have been few systematic works on the SM effect in Co and Co-based alloys. In this study, the fcc/hcp martensitic transformation and the SM effect were investigated in Co-Al binary alloys(mole fraction of Al=0~16%).The γ/ε martensitic transformation temperatures were found from the DSC measurements to decrease with increasing Al content, while the transformation temperature hystereses were observed to increase from 60 ℃ at x(Al)=0 to 150 ℃at x(Al)= 16%. The SM effect evaluated by a conventional bending test was enhanced by the addition of Al over 4%(mole fraction) and Co-Al alloys containing over 10%(mole fraction) exhibit a good SM effect associated with the hcp →fcc reverse transformation above 200 ℃. The SM effect was significantly improved by precipitation ofβ (B2) phase and the maximal shape recovery strain of 2. 2% was obtained, which can be explained by precipitation hardening. The crystallographic orientations between theβ, ε and γ phases were also determined. Finally, the magnetic properties were investigated and it was found that the Curie temperature and saturation magnetization of Co-14% Al(mole fraction) are 690 ℃and 120 emu/g, respectively. It is concluded that the Co-Al alloys hold promise as new high-temperature and ferromagnetic SM alloys. 相似文献