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排序方式: 共有451条查询结果,搜索用时 15 毫秒
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Metallurgist - A characteristic feature of serpentine oxidized nickel ores (ONO) of the Serov deposit (≈ 1 wt.% Ni) is the increased content of iron and magnesium. The main nickel-containing... 相似文献
446.
M. R. Tarasevich V. A. Bogdanovskaya Yu. G. Gavrilov G. V. Zhutaeva L. P. Kazanskii E. M. Kol’tsova A. V. Kuzov O. V. Lozovaya A. D. Modestov M. V. Radina V. Ya. Filimonov 《Protection of Metals and Physical Chemistry of Surfaces》2013,49(2):125-144
Creation of multicomponent catalytic systems is the main way to decrease the content of or completely replace Pt in fuel cell cathodes. Compared to the conventional catalytic systems, production of PtCoCr catalysts on different substrates (XC-72 carbon nanotubes, TiO2) differs in high-temperature conditions and the use of nitrogen-containing transient-metal precursors. According to electrochemical and structural studies, during synthesis and subsequent treatment, alloy nanoparticles with a core-shell structure enriched in platinum are formed on a carbon material doped with nitrogen. The ligand effect of the alloy core results in an increase in the electron density of the platinum d-level, acceleration of oxygen reduction, and deceleration of water molecule discharge and platinum corrosion. A architecture of membrane electrode assembly involving PtCoCr-based active layers of varying composition is developed for fuel cells operating at a temperature of 65°C in hydrogen-air and hydrogen-oxygen environments. In both cases, the use of PtCoCr instead of monoplatinum catalysts enabled us to halve the platinum consumption at the same discharge current density and specific power. The results of life testing and potential cycling of membrane electrode assemblies under severe conditions showed that the resistance of PtCoCr systems is not inferior to platinum. 相似文献
447.
The formation of thin titanium oxide films by pulling substrates from an alcohol solution of titanium tetraisopropoxide has
been investigated. It is shown that the deposited titanium oxide layer consists of a continuous film and titanium oxide globules
on its surface. It is found that the density and height of the globules depend on the pulling rate from the solution and the
relative humidity in the working chamber, while the thickness of the continuous titanium oxide film is relatively constant. 相似文献
448.
We describe the stages of works on examining the technical state and extending the service life of the main elements of steam
turbines. As an example we analyze unique experience gained from activities performed from 1993 to 2010 for examining the
technical state and determining the remaining service life of VPT-50-4 turbines operating under the same conditions at the
same thermal power station with a view to extend their service life. 相似文献
449.
Aleksey A. Vedyagin Mikhail S. Gavrilov Alexander M. Volodin Vladimir O. Stoyanovskii Elena M. Slavinskaya Ilya V. Mishakov Yuri V. Shubin 《Topics in Catalysis》2013,56(11):1008-1014
Three-way catalysts with low content of Pd–Rh alloy particles used as active components were synthesized and studied. Monometallic and bimetallic mixed catalysts with corresponding precious metals loading were chosen as reference samples. The catalytic activity was tested in oxidation of carbon monoxide, hydrocarbons, and in nitrogen oxides reduction. The stability of the samples was estimated by prompt thermal aging in situ technique. Ethane hydrogenolysis testing reaction was used to determine the surface concentration of Pd and Rh, and to confirm the alloy formation. Photoluminescence and electron paramagnetic resonance spectroscopy were applied to clarify the possible reasons of deactivation and to elucidate the mechanism of stabilization. It was shown that Pd–Rh alloyed catalyst is characterized by comparable activity and enhanced stability. While the Pd and Rh particles of monometallic samples were found to interact with support at high temperatures resulting in sintering and bulk diffusion, the particles of alloy type kept their initial state of dispersion and catalytic activity. 相似文献
450.
NataliyaS. Goulioukina GrigoriiN. Bondarenko SergeyE. Lyubimov VadimA. Davankov KonstantinN. Gavrilov IrinaP. Beletskaya 《Advanced Synthesis \u0026amp; Catalysis》2008,350(3):482-492
It was shown that the catalytic hydrogenation of α‐iminophosphonates by molecular hydrogen can serve as a convenient method for the synthesis of racemic and optically active α‐aminophosphonates. Up to 94% ee was achieved in the rhodium‐catalyzed enantioselective hydrogenation using chiral ligand (R)‐BINAP. 相似文献