共查询到20条相似文献,搜索用时 15 毫秒
1.
Attila Csik Kálmán Vad Enikő Tóth-Kádár László Péter 《Electrochemistry communications》2009,11(6):1289-1291
Conventional and reverse depth profile analysis of electrodeposited Fe–Co–Ni alloys was performed by secondary neutral mass spectrometry (SNMS). It was found that the reverse sputtering method gave a much better depth resolution at the vicinity of the substrate. The reverse SNMS spectra showed that the deposition of Fe–Co–Ni alloys starts with the formation of an Fe-rich zone followed by an increase in Co concentration, then the nickel content increases and a steady-state alloy composition is achieved. At high current density, the initial depth pattern reproduces itself twice before the composition becomes stable. It was concluded that the varying depth profile is a consequence of the anomalous nature of the codeposition of the alloy components, the depletion of the electrolyte with respect to the metal salts, and the dependence of the intensity of the hydrogen evolution on the deposit surface composition. 相似文献
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A fundamentally new solution of the challenge of producing alloys in the Fe–Co system with an oxygen concentration below 10 ppm (10–3%) has been for the first time justified and demonstrated. A thermodynamic analysis showed that decreasing the pressure of the gas phase over the melt significantly increases the deoxidizing power of carbon. At cobalt and carbon contents characteristic of soft- and hard-magnetic alloys and a total pressure of 0.01 atm, the oxygen concentration was 10–1 ppm (10–3–10–4%). With increasing cobalt content of the melt, the deoxidizing power of carbon increases. The curves of the oxygen solubility in carbon-containing iron–cobalt melts pass through a minimum, which shifts toward lower carbon contents with increasing cobalt content of the melt. 相似文献
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Performed for the first time, the thermodynamic analysis of oxygen solutions in titanium-containing Fe–Co melts showed that the deoxidizing power of titanium with increasing cobalt content of the melt first decreases, reaches a minimum at a cobalt content of 20%, and then increases. The titanium contents [%Ti]* at equilibrium points between the oxide phases TiO2, Ti3O5, and Ti2O3 were determined. The curves of the oxygen solubility in titanium-containing iron–cobalt melts pass through a minimum, which shifts toward lower titanium contents with increasing cobalt content of the melt. Further alloying with titanium leads to an increase in the oxygen concentration of the melt so that the higher cobalt content of the melt, the steeper the increase in the oxygen content after the minimum as titanium is added to the melt. 相似文献
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V. M. Krutskikh A. B. Drovosekov Yu. D. Gamburg A. D. Aliev B. F. Lyakhov V. M. Martynenko Yu. M. Shul’ga 《Russian Journal of Electrochemistry》2016,52(2):106-114
The data on the mechanism of electroless (catalytic) deposition of Co–Re–B coatings are obtained by determining the donor capacitance of dimethylamine borane (DMAB) (CH3)2HN · BH3 reductant and the oxidation level of its hydride hydrogen. From the results of the study of isotopic composition of evolved hydrogen, it is concluded that the oxidation level of DMAB hydride hydrogen depends on the catalytic activity of the alloy. The alloys containing up to 46 at % rhenium were produced by the electroless deposition. 相似文献
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Arpit Kaistha Vivek Modgil V. S. Rangra 《Journal of Thermal Analysis and Calorimetry》2017,129(3):1323-1331
The glassy compositions of Ge 16 Se 52 Te 32?x Sb x system, obtained using rapid melt quenching technique, have been characterized by calorimetric study at different heating rates in this study. A systematic investigation of the crystallization kinetics is carried out for these compositions. Composition corresponding to atomic % 8 of Sb has good thermal stability. The material exhibits the unique thermal properties, which makes it suitable to use for electrical or memory switching devices. Various thermal parameters, activation energies of glass transition and crystallization are calculated using relevant approaches. 相似文献
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Electrochemically deposited Zn–Co alloys under various deposition conditions were investigated using anodic linear sweep voltammetry
for phase structure determination, scanning electron microscopy for surface morphology analysis, atomic absorption spectroscopy
for determination of chemical composition, and polarization measurements and open circuit potential measurements for determination
of corrosion properties. The influence of deposition current density, temperature, and composition of deposition solution
on the phase structure and corrosion properties of Zn–Co alloys was studied. It was shown that the ratio of cobalt to zinc
ions in the plating bath strongly affects the chemical content and phase structure, as well as corrosion stability, of Zn–Co
alloys. Zn–Co alloys deposited from plating baths with the lowest and the highest ratios of cobalt and zinc ions exhibited
the lowest corrosion rate. 相似文献
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Ľubomíra Drozdová Bedřich Smetana Simona Zlá Vlastimil Novák Monika Kawuloková Silvie Rosypalová Lenka Řeháčková Ondřej Martiník Petr Dostál 《Journal of Thermal Analysis and Calorimetry》2018,133(1):41-48
Three alloys based on Fe–C–Cr were studied. These alloys contained carbon in a range of 0.308–0.380 mass% and chromium 1.058–4.990 mass%. Temperatures of solidus (onward used as TS), liquidus (onward used as TL) and peritectic transformation (onward used as TP) were studied in the high-temperature region. These temperatures were obtained using two thermal analysis methods: differential thermal analysis (onward used as DTA) and simple thermal analysis (onward used as TA). The Setaram Setsys 18TM was used for experiments with employment of the DTA method. All measurements were taken in an inert atmosphere of pure argon at heating rate of 10 °C min?1, and simple TA method was used for the experiments with the use of the Netzsch STA 449 F3 Jupiter. Measurements were taken in inert atmosphere of pure argon at a heating and cooling rate of 5 °C min?1. Phase transformation temperatures were obtained by heating and cooling process and were approximated to “equilibrium conditions” (DTA method: zero heating rate and sample mass, standard, TA method: only standard) (?aludová et al. in J Therm Anal Calorim 112:465–471, 2013a. doi: https://doi.org/10.1007/s10973-012-2847-8; J Therm Anal Calorim 111:1203–1210, 2013b. doi: https://doi.org/10.1007/s10973-012-2346-y). The experimental data were compared and discussed with the calculation results using IDS (solidification analysis package) software (onward used as SW) Thermo-Calc and the TCFE8 (Thermo-Calc Fe-based alloys) database. The results of the two alloys were compared with those published for similar steels. The experimentally obtained transition temperatures were close to the calculated values. The solidus, liquidus and peritectic transformation temperatures were lowered with increasing carbon (range 0.308–0.380 mass%) and chromium content (range 1.058–4.990 mass%). The smallest difference between the experimental results and theoretical calculations was observed at the liquidus temperature for all alloys. Nonetheless, the difference measured for the solidus temperatures was much greater. 相似文献
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N. M. Ivanova E. A. Soboleva Ya. A. Visurkhanova 《Russian Journal of Applied Chemistry》2016,89(7):1072-1081
Bimetallic Co–Cu polyaniline composites were produced by oxidative polymerization of aniline, with ammonium peroxydisulfate and hydrogen peroxide as oxidizing agents. Co(II) and Cu(II) chlorides were introduced into the polymer by the in situ method. It was found that the phase constitution of the composites is affected by their synthesis conditions and content of both metals in them. The electrocatalytic activity of the composites in the electrohydrogenation of p-nitroaniline in an aqueous-alcoholic-alkaline medium of the catholyte was studied and found to exceed that of composites synthesized with the use of H2O2 and evaporation of the solvent. 相似文献
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Balbir Singh Patial Nagesh Thakur S. K. Tripathi 《Journal of Thermal Analysis and Calorimetry》2011,106(3):845-852
Calorimetric study of Se85−x
Te15Sn
x
(x = 0, 2, 4 and 6) glassy alloys have been performed using Differential Scanning Calorimetry (DSC) under non-isothermal conditions
at four different heating rates (5, 10, 15 and 20 °C/min). The glass transition temperature and peak crystallization temperature
are found to increase with increasing heating rate. It is remarkable to note that a second glass transition region is associated
with second crystallization peak for Sn additive Se–Te investigated samples. Three approaches have been employed to study
the glass transition region. The kinetic analysis for the first crystallization peak has been taken by three different methods.
The glass transition activation energy, the activation energy of crystallization, and Avrami exponent (n) are found to be composition dependent. The crystallization ability is found to increase with increasing Sn content. From
the experimental data, the temperature difference (T
p − T
g) is found to be maximum for Se83Te15Sn2 alloy, which indicates that this alloy is thermally more stable in the composition range under investigation. 相似文献
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《Electrochemistry communications》2008,10(1):32-37
Localized corrosion of aluminum alloys is a major issue worldwide and in spite of decades of work, several questions still remain unresolved. In this study we focus on key issues in the context of localized corrosion of Al–Cu–Mg/Al–Mg–Cu alloys that have not been adequately addressed. By careful electrochemical exposure along with high-resolution electron microscopy, we reveal that microstructural features down to a few nanometers in size can behave as unique electrochemical entities. In addition, not only is this critical to emerging damage accumulation models, but we also reveal that significant dissolution can occur at potentials below the breakdown potential of the bulk alloy. This work has potentially wide consequences in the interpretation of Al alloy corrosion and alloys design for corrosion resistance. 相似文献
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叔胺的酰胺化反应,特别是带有苄基的叔胺的酰胺化,一直是有机合成中的难题。采用介孔二氧化硅掺杂金属的方法制备的一种双金属高活性纳米催化剂Fe-Co@SHSss,在叔丁基过氧化氢(TBHP)的氧化作用下对模拟底物N,N-二甲基苄胺的酰胺化显示出良好的催化效果,得到的反应产物N,N-二甲基苯甲酰胺的产率可以达到80%左右,产物结构经过1H NMR,13C NMR和MS(ESI)表征。使用叔丁基过氧化氢构建的清洁的反应体系,比较符合绿色化学的原则,这对于叔胺的氧化具有十分重要的意义。 相似文献
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Yingting Wang Jiangfeng Huang Xiaomeng Xia Xinhua Peng 《Journal of Saudi Chemical Society》2018,22(2):129-135
A highly efficient catalyst Fe–Co/sulfonated polystyrene (Fe–Co/SPS) was introduced and synthesized, which catalyzed BV oxidation of ketones with aqueous hydrogen peroxide to give the corresponding lactones in high yield and selectivity. Solid acid catalyst of Fe–Co/SPS has been prepared by using the 98-wt% sulfuric acid as the sulfonating agent and CoCl2 combined FeCl3 as sources of metal ions. Various physical–chemical characterizations including FT-IR, XRD, SEM and TGA, revealed that bimetallic ions Fe3+–Co2+ species in the sulfonated polystyrene framework were responsible for the catalytic activities. The BV reaction catalyzed by Fe–Co/SPS highlighted the special effects between metal ions and protonic acids as well as solvent-free heterogeneous catalytic oxidation with excellent conversion. 相似文献
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Quantitative online NMR spectroscopy was used for studying the species distribution in solutions of carbon dioxide in aqueous monoethanolamine (MEA) and diethanolamine (DEA). The mass fraction of the amine in the unloaded solution was 0.2 and 0.3 g/g, respectively, the carbon dioxide loading was up to 1.1 ??molCO2/molamine, temperatures were between 293 and 353 K. A special apparatus was designed that allows preparing the mixtures gravimetrically and applying pressures up to 25 bar to keep the carbon dioxide in solution. It was coupled to a 400 MHz NMR spectrometer by heated capillaries. By using both 1H and 13C NMR spectroscopy quantitative information on the concentrations of the following species were obtained: amine, carbamate, bicarbonate, and carbon dioxide. Due to the fast proton transfer between molecular and protonated amine, only the sum of their concentrations can be determined. Furthermore, a byproduct, 2-oxazolidone, was observed and quantified. The experimental data were used for developing a thermodynamic model of the studied electrolyte solutions based on the extended Pitzer GE-model. In the model development, also vapor–liquid equilibrium data from the literature were included. The model gives reliable results both for the species distribution and the vapor–liquid equilibrium of the studied mixtures. 相似文献
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V. K. Yatsimirskii E. V. Ishchenko N. A. Boldyreva N. N. Khomenko G. G. Tsapyuk 《Theoretical and Experimental Chemistry》2001,37(5):315-318
We have used thermal desorption to study the catalytic activity in CO oxidation and the state of the surface of an iron–cobalt oxide system. In the region of co-existence of the spinels CoFe2O4 and CoCo2O4, the activity and specific surface area are practically constant. We observe substantial deviation from additivity for the catalytic activity in the region of co-existence of the oxide Fe2O3 and the spinel CoFe2O4. We have established that chemisorption of CO on the surface of the oxides leads to formation of a number of stable forms of chemisorbed CO2, among which the least strongly bound 2 form is characteristic of the most active catalysts. 相似文献