The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Min Zhu - One of the best experts on this subject based on the ideXlab platform.
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controlling nanocrystallization and hydrogen storage property of mg based amorphous alloy via a gas Solid Reaction
Journal of Alloys and Compounds, 2016Co-Authors: Huaijun Lin, Chi Zhang, Hui Wang, Liuzhang Ouyang, Yunfeng Zhu, Liquan Li, Weihua Wang, Min ZhuAbstract:Abstract A valid strategy via a gas-Solid Reaction for preparing Mg-based nanocomposite with controllable crystallite size and suitable for massive production is proposed. The nanocomposites consisting of well-dispersed catalytic nano-Mg 2 NiH 4 /CeH 2.73 embedded in the nano-MgH 2 matrix with crystallite sizes of all phases below 10 nm are fabricated via controlling activation temperature and hydrogen gas (H 2 ) pressure upon the amorphous Mg 80 Ce 10 Ni 10 alloy. Increasing H 2 pressure and reducing temperature are beneficial for obtaining fine hydrides, leading to lowered hydrogen desorption temperature. MgH 2 and CeH 2.73 gradually grow up with the increase of de-/re-hydrogenation cycles, while Mg 2 NiH 4 remains stable during cycling. After 15 de-/re-hydrogenation cycles, the finest nanocomposite shows remarkably reduced activation energy of dehydrogenation of 87 ± 7 kJ/mol (∼160 kJ/mol for commercial MgH 2 ).
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synthesis and hydrogen storage characteristics of mg b h compounds by a gas Solid Reaction
International Journal of Hydrogen Energy, 2013Co-Authors: Hui Wang, Z G Zhang, J W Liu, Min ZhuAbstract:Abstract Magnesium borohydride [Mg(BH4)2] is an attractive complex hydride for hydrogen storage. In this study, attempts to synthesize Mg(BH4)2 were carried out by a Solid–gas Reaction through MgH2 and B2H6 in the absence of a liquid medium. The source of B2H6 was obtained by heating a mixture of NaBH4 and ZnCl2. The profile of pressure versus temperature indicated that the absorption kinetics of B2H6 by MgH2 were slow. Structural analysis confirmed the formation of Mg–B–H compounds. The Reaction products presented two-step hydrogen release during heating. A small amount of hydrogen could be released from the as-synthesized Mg–B–H compounds at a low temperature of 215 °C. The slow Reaction kinetics were significantly affected by the surface conditions of the MgH2 powders.
Z G Zhang - One of the best experts on this subject based on the ideXlab platform.
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synthesis and hydrogen storage characteristics of mg b h compounds by a gas Solid Reaction
International Journal of Hydrogen Energy, 2013Co-Authors: Hui Wang, Z G Zhang, J W Liu, Min ZhuAbstract:Abstract Magnesium borohydride [Mg(BH4)2] is an attractive complex hydride for hydrogen storage. In this study, attempts to synthesize Mg(BH4)2 were carried out by a Solid–gas Reaction through MgH2 and B2H6 in the absence of a liquid medium. The source of B2H6 was obtained by heating a mixture of NaBH4 and ZnCl2. The profile of pressure versus temperature indicated that the absorption kinetics of B2H6 by MgH2 were slow. Structural analysis confirmed the formation of Mg–B–H compounds. The Reaction products presented two-step hydrogen release during heating. A small amount of hydrogen could be released from the as-synthesized Mg–B–H compounds at a low temperature of 215 °C. The slow Reaction kinetics were significantly affected by the surface conditions of the MgH2 powders.
Thomas Turek - One of the best experts on this subject based on the ideXlab platform.
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Oxidation of copper at high temperature as an example for gas-Solid Reactions in a downer reactor - experiments and model-based analysis
Chemical Engineering Science, 2016Co-Authors: Maximilian A. Schöß, Frank Schulenburg, Thomas TurekAbstract:The kinetics of a gas-Solid Reaction at high temperatures were studied in a downer reactor of 2.8 m length. As an example, the oxidation of copper particles was carried out at different wall temperatures (1073 K-1323 K), oxygen concentrations (14 Vol.-%-67 Vol.-%), and particle diameters (51 μm-156 μm). Although the residence time of the particles was of the order of 1-4 s only, considerable copper conversions could be achieved. XRD, EDX and SEM analysis of the formed products revealed that single layer formation of cuprous oxide prevails up to oxygen concentrations of about 25 Vol.-%. At higher oxygen concentrations, double layer oxidation occurs with a second cupric oxide layer forming on top of cuprous oxide. The remaining core radius of unreacted copper was determined through a combination of density measurements, analysis of TPR spectra, and direct SEM observation. Although significant scattering of the individual measurements was observed, it could be shown by independent elemental analysis of the products that the average values from all measurements are reliable. For quantitative evaluation of the measurements we developed a one-dimensional downer reactor model which allowed to calculate the residence time and particle temperature as a function of reactor length. Using this information we derived Solid state diffusion coefficients, the activation energies of which agreed well with literature data. Overall it could be shown that the progress of a gas-Solid Reaction in a downer reactor can be successfully described with a combination of experimental methods and subsequent model-based data analysis.
Changqing Liu - One of the best experts on this subject based on the ideXlab platform.
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Diffusion barrier property of electroless Ni-W-P coating in high temperature Zn-5Al/Cu solder interconnects
Journal of Alloys and Compounds, 2017Co-Authors: Li Liu, Zhaoxia Zhou, Guang Chen, Fengshun Wu, Zhiwen Chen, Changqing LiuAbstract:The operating temperature of high-temperature electronics can significantly promote the growth of intermetallic compounds (IMCs) at solder/substrate interfaces, particularly for low-cost Zn-based solders because of the rapid rate of Reaction of Zn with Cu. Thus, a reliable and robust diffusion barrier is indispensable for suppressing the Reactions between solder and substrate. In this work, a ternary Ni-W-P alloy was prepared via electroless plating. Its diffusion barrier property was evaluated by comparing the microstructures of IMC layers in Zn-5Al/Ni-W-P/Cu and Zn-5Al/Cu interconnects after liquid-Solid Reaction for prolonged durations. When the Reaction lasted for 30 min, the thickness of the Al3Ni2 produced in the Zn-5Al/Ni-W-P/Cu solder interconnects was only 2.15 μm, whereas the thickness of the interfacial layer of Cu-Zn IMCs (CuZn4, Cu5Zn8 and CuZn) at the Zn-5Al/Cu interface was 94 μm. Because of the unbalanced growth of the IMCs in the Zn-5Al/Cu interconnects, notable numbers of Kirkendall voids were identified at the CuZn4/Cu5Zn8, Cu5Zn8/CuZn and CuZn/Cu interfaces after prolonged liquid-Solid Reaction. By contrast, the Al3Ni2 layer in the Zn-5Al/Ni-W-P/Cu solder joints remained intact, showing the potential to effectively enhance the mechanical reliability of electronic devices.
Ziad Habib - One of the best experts on this subject based on the ideXlab platform.
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study of the hydration of cao powder by gas Solid Reaction
Cement and Concrete Research, 2011Co-Authors: Eric Serris, Patrice Nortier, Michel Soustelle, Loic Favergeon, Michèle Pijolat, Thierry Chopin, Robert Sebastian Gartner, Ziad HabibAbstract:Hydration of CaO powders by Reaction with water vapor has been studied in isothermal and isobaric conditions. Experimental tests were performed within the temperature range of 70 °C-420 °C and with a water vapor pressure from 5 to 160 hPa by means of a thermogravimetric device. Two powders, exhibiting slight differences in their physical properties, were studied. However, for one of the powders and under some temperature and pressure conditions, the Reaction is not complete. The difference of behavior between both CaO powders was interpreted by considering the effect of the morphological properties on the mechanism of growth of Ca(OH)2.
