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排序方式: 共有690条查询结果,搜索用时 31 毫秒
61.
Hugo R. Fernandes Dilshat U. Tulyaganov Maria J. Pascual Vladislav V. Kharton Aleksey A. Yaremchenko José M.F. Ferreira 《Journal of the European Ceramic Society》2012,32(10):2283-2292
The effects of K2O content on sintering and crystallization of glass powder compacts in the Li2O–K2O–Al2O3–SiO2 system were investigated. Glasses featuring SiO2/Li2O molar ratios of 2.69–3.13, far beyond the lithium disilicate (LD-Li2Si2O5) stoichiometry, were produced by conventional melt-quenching technique. The sintering and crystallization behaviour of glass powders was explored using hot stage microscopy (HSM), scanning electron microscopy (SEM), differential thermal (DTA) and X-ray diffraction (XRD) analyses. Increasing K2O content at the expense of SiO2 was shown to lower the temperature of maximum shrinkage, eventually resulting in early densification of the glass-powder compacts. Lithium metasilicate was the main crystalline phase formed upon heat treating the glass powders with higher amounts of K2O. In contrast, lithium disilicate predominantly crystallized from the compositions with lower K2O contents resulting in strong glass–ceramics with high chemical and electrical resistance. The total content of K2O should be kept below 4.63 mol% for obtaining LD-based glass–ceramics. 相似文献
62.
63.
Svetlana Pavlova Tamara Kharlamova Vladislav Sadykov Tamara Krieger Vitaly Muzykantov Yulia Bespalko 《传热工程》2013,34(11-12):904-916
Mixed ionic?electronic conducting nanocomposites comprising complex oxides - perovskite (lanthanum-strontium nickelate-ferrite [LSFN]) and gadolinium-doped ceria (GDC) have been prepared via ultrasonic dispersion of nanocrystalline powders of LSFNx and GDC in organic solvent with addition of surfactant, followed by drying and sintering up to 1300°C. Their structural and surface properties have been studied by x-ray diffraction, ultraviolet–visible (UV-vis) electron spectroscopy, transmission electron microscopy with elemental analysis, and x-ray photoelectron spectroscopy. Results of impedance spectroscopy, oxygen isotope exchange, O2 temperature-programmed desorption, weight, and conductivity relaxation experiments have revealed a strong positive effect of perovskite?fluorite nanodomain interfaces in composite on the oxygen mobility and reactivity. Testing in wet H2/air feeds for a button-size cell with functionally graded LSFN0.4–GDC cathode layer supported on a thin YSZ layer covering Ni/YSZ cermet has demonstrated high and stable performance, promising for the practical application in the intermediate temperature range. 相似文献
64.
Vladimir Ivanovich Lysenko Sergey Bardakhanov Alexey Korchagin Nikolay Kuksanov Alexander Lavrukhin Rustam Salimov Sergey Fadeev Vladislav Cherepkov Mikhail Veis Andrey Nomoev 《Bulletin of Materials Science》2011,34(4):677-681
Electron-beam evaporation of various natural and industrial materials in the atmosphere of different gases at atmospheric
pressure can be used for the synthesis of nanosize powders. These powders are characterized by high purity and may exhibit
unusual properties. In particular, nanopowders of silicon dioxide and oxide (SiO2, SiO), magnesia (MgO), alumina (Al2O3), titania (TiO2), gadolinium oxide (Gd2O3), various metals (tantalum, molybdenum, nickel, aluminium, copper, silver), semiconductor (Si), nitrides (AlN, TiN), and
some other substances had been produced. The process of nanopowder synthesis is highly effective; in particular, the yield
of oxides can exceed ten kilograms per hour. 相似文献
65.
66.
H. F. Chen G. D. Wei X. Han S. Li P. P. Wang M. Chubik A. Gromov Z. P. Wang W. Han 《Journal of Materials Science: Materials in Electronics》2011,22(3):252-259
In this paper, we report a facile, an environmental friendly ultrasonic-assisted hydrothermal route for preparation of goethite
flower structures using Fe nanopowders at low temperature (85°C). The flower structure consisted of tens of hundreds of nanowires
and such structures can further self-assemble with the flake with micro size area. Structural, morphological, and elemental
analysis revealed that the products consisted of flower-like structures with high structural uniformity, good crystal quality,
and high yields. Influencing factors such as the reaction temperature, pH value, and the deposition time were systematically
investigated. A possible formation mechanism was proposed on the basis of the experimental results. Magnetic measurements
showed that the as-obtained goethite flowers exhibited weakly ferromagnetic characteristics at room temperature, which were
quite different from those of the corresponding bulk materials. 相似文献
67.
O. B. Gromov A. A. Mikhalichenko P. I. Mikheev V. I. Nikonov V. G. Soloviov 《Atomic Energy》2010,109(2):96-101
The problem of the formation of uranium residue in spent sodium fluoride sorbent is studied. The mechanisms of the formation
of un-desorbed uranium residue with thermal desorption of uranium hexafluoride from the surface sodium fluoride are examined.
It is proved that hydrolysis of sorbed and gaseous uranium hexafluoride under the conditions of sublimate-separation production
is impossible. The most likely mechanism of residue formation is partial reduction of hexavalent uranium, which is due to
the chemical properties of the system UF6–NaF. A possible process of uranium reduction as a result of nuclear-chemical transformations requires study and experimental
confirmation. 相似文献
68.
Siniša N. Dodić Vladislav N. Zekić Vesna O. Rodić Nedeljko Lj. Tica Jelena M. Dodić Stevan D. Popov 《Renewable & Sustainable Energy Reviews》2010,14(9):3171-3177
The Autonomous Province of Vojvodina is an autonomous province in the Republic of Serbia. It is located in the northern part of the country, in the Pannonia plain. Vojvodina is an energy-deficient province. The average yearly quantity of the cellulose wastes in Vojvodina amounts to about 9 millions tons barely in the agriculture, and the same potential on the level of Serbia is estimated to almost 13 million tons. Only minor part of straw is utilized, and almost two-thirds are incinerated on fields owing to the problems during plowing under. The large sector in Serbia utilizes only about 15% of straw, while the individual one utilizes about 50% of straw and 20% of cornstalks. Environment pollutions, abandonment of the utilization of at least of one-third of the yield and extermination of the natural resources, primarily of humus, represent very adverse results of such procedures. Main problems with respect to the profitable usage of straw and other post-harvest residues are high expenses of their collection (collecting, balling or some other manner of compression), transportation from production- to the usage cites, as well as their handling and storaging. The agricultural production in Serbia should be based on the system of farms. For the efficient farming, it is obvious to organize life of producer and of his family immediately close to the production capacities. For the agriculture development, it is obvious to create a system of premiums, efficient crediting and the elaborated tax system that could create a basis for the certitude of work, confidence and constant growth of production, together with the mentioned and other measures. As the result of the activities oriented to substitution of the classical energents with energy obtained from biomass, farm that is in a higher degree energetically independent should be created. In such case, farms should apply the basic principles of the cleaner manufacturing, as an integral part of the concept of the sustainable development. 相似文献
69.
O. B. Gromov V. V. Vodolazskikh P. V. Zernaev V. I. Ivanov A. V. Sigailo M. I. Sterkhov V. K. Prokudin 《Atomic Energy》2009,107(1):27-31
The processes occurring during accidental discharges of liquid uranium hexafluoride in the production rooms of the Chelnok-T
section in the isotope separation plant at Siberian Chemical Combine are examined. The purification system, which uses KhP-MMD
and KhP-MD chemical absorbers, permits localizing very quickly any accidental discharges of uranium hexafluoride and protect
the atmosphere in the plant from harmful effects of fluorine-contained gases. The absorbers effectively catch HF (99.97%)
and UF6 (>99.9%) and have a high working capacity 30.5 mass% with respect to the fluorine ion. The system for catching and dispersing
harmful contaminants provides the required sanitary standard with respect to atmospheric air on the territory of the plant
and at the nearest populated points. 相似文献
70.
Tsellermaer V. V. Popova N. A. Klimashin S. I. Tihonikova O. V. Konovalov S. V. Kozlov E. V. Gromov V. E. 《材料研究与应用》2005,(3):224-224
The quantitative study of the hardening velocity influence on the α-phase morphology in 30CrNi3MoVA (0.3% C, 1% Cr,3% Ni, 1% Mo, 1% V) cast average alloy steel after gomogenization (1125℃, 13 h), normalizing (980℃, 10 h) and high tempering (660℃, 10 h. with cooling on air) is the aim of this work.…… 相似文献