قائمة الطعام
Furthermore, the milling in benzene destabilizes the alloy hydride. The ball milling in organic solvent offers a new way for magnesium-based hydrogen storage materials, exploiting their higher ...
A Ti-NaAlH 4 sample was then ball-milled for 2 h using a SPEX 8000 high-energy mixer/mill at a milling speed of 1,000 rpm, and the weight ratio of ball to powder was 10 : 1. 0.5–1.0 gram of sample was subjected to ball-milling each time in a 65 cm 3 SUS 304 vial by ZrO 2 balls of 1.3 cm in diameter.
and controlled size distribution. Magnesium hydride (MgH 2) was supplied by Sigma-Aldrich and submitted to ball milling with tungsten carbide balls under H 2 atmosphere for 24 hours at 300 rpm using a Fritsch P-6 planetary mill. After that, the MgH 2 was milled for 20 minutes more with 5 wt. (%) of carbon nanotube. The samples were handled in a ...
The complex hydride was prepared by ball milling under argon and hydrogen atmosphere from 2Mg + Fe and 2MgH2 + Fe compositions. The samples were characterized by X-ray powder diffraction and scanning electron microcopy. Kinetics of hydrogen absorption and desorption were measured in a Sievert's apparatus. We found that
Neto et al. (2017) doped TiFe compound into MgH 2 and concluded that a fine dispersion could be achieved by increasing milling time or using higher energy ball mill. To attain the best hydrogen kinetics, the sample prepared in the planetary mill for 36 h was the optimum selection and the MgH 2 + 40 wt%TiFe sample milled for 36 h could release ...
Titanium hydride with a body centred tetragonal structure was rapidly synthesized at room temperature by ball milling titanium powders under a hydrogen atmosphere. The structure evolution was monitored by x-ray diffraction and Rietveld analysis. Unit cell volume dilation suggests the hydrogenation process begins with the formation of a titanium - hydrogen solid …
After ball milling -a) hydride-a)-a)-a) hydride After pyrolysis nitride nitride nitride nitride hydride hydride hydride hydride hydride a) amorphous However, the samples obtained after ball milling of the dihydrides of cerium, praseodymium, neodymium or samarium with ammonia were found to be converted into the nitride when subjected to ...
doping was performed by ball milling NaAlH4 with Ti(OiPr)4 and Zr-fluoride. The H2 evolution versus temperature for the as -synthesized materials is shown in Figure 3. The H2 evolution for the second Figure 4. Second-Cycle Desorption for 8 Hydride Samples Analyzed in a Single Run desorption, after re-hydriding, is shown in Figure 4.
In this study, magnesium hydride co-catalyzed by ZrO 2 and Ni nanostructures were prepared using a high-energy ball-milling approach. The storage material was investigated for its composition, hydrogen adsorption rates, and thermodynamics. Hydrogen absorption and desorption rates were improved without increasing milling time.
Hydride has been introduced into Al-BiCl3 composite by ball milling. The hydrogen generation performances of Al-BiCl3-hydride composite have been effectively promoted. Among of them, Al-BiCl3-Li3AlH6 is found to have the best performance of hydrogen yield (1293 mL·g-1), the conversion efficiency (94.4%) and the max HG rate (2098 mL·g-1·min-1) at 25 oC.
Among the most commonly utilized mill devices for hydride compounds and system preparation at laboratory scale, it is possible to mention: (1) Magneto Uni-ball mill device (low energy, Pg: 0.0003–0.002 W/g), (2) Planetary Fritsch-P6 (middle energy, Pg: 0.01–0.22 W/g), and Vibratory Spex 8000 M mill device (high energy, Pg < 0.24 W/g) [60 ...
The cerium hydride phase formed during ball-milling was stable at high temperatures and, thus, the formation of this phase reduced the amount of desorbed hydrogen from the milled MgH 2-catalyst mixture. Increasing the milling time to 20 and 30 h also reduced the temperature of hydrogen desorption.
Over decades of research effort, ball milling and catalytic doping have been recognized as two important avenues to improve the kinetics of hydrogen absorption and desorption by magnesium hydride [10], [11], [12], [13], [14], [15], [16], [17].
elemental Mg powders after 200 h of high-energy ball milling under a hydrogen gas pressure of 50 bar. The as-prepared metal hydride powders were contaminated with 2.2 wt. % of FeCr-stainless steel that was introduced to the powders upon using stainless steel milling tools made of the same alloy.
Magnesium hydride is one of the most promising candidates for solid-state hydrogen storage and thermal energy storage applications. The effects of V-based solid solution alloys on the hydrogenation and dehydrogenation behavior of magnesium hydride are studied. Significant reduction of the dehydrogenation temperature and improvements of the kinetics of both …
These hydride systems are capable of releasing from ~4 to 7 wt.% H 2 at the ambient temperature during a reasonably short duration of ball milling. The second group encompasses systems that generate H 2 at slightly elevated temperature (up to 100 °C).
Mg 0.25 Mn 0.75, prepared through ball milling MgH 2 and Mn powders, is a nanocomposite where the nanometer-sized MgH 2 domains are randomly embedded in a Mn matrix. This sample readily and reversibly absorbs and desorbs deuterium even at a temperature of 200 °C without the addition of any catalysts.
The milling was carried out at various milling speeds, namely 300, 660, and 900 rpm. Results suggested that the structure of the nanotubes is preserved with prolonged grinding of magnesium hydride and SWCNT in a ball mill for 180 min at …
Ball milling. Mechanochemical synthesis using ball milling of magnesium hydride with and without additives and alloying metals has been employed to produce defect-enhanced potential hydrogen storage materials . The high-pressure, high-energy impacts of the balls and vial walls repeatedly compress, fracture and cold-weld the powder particles.
10%Three types of alloys, nickel mixed, nickel ball-milled and nickel coated Mg2Ni alloy, were used as the active material of metal hydride electrodes. The ball-milling of the alloy with nickel powder results in an amorphous or nanocrystaline phase. Chemical coating of the alloy with nickel was carried out at 25°C.
Nanocrystalline MgH 2 with fine and evenly dispersed Nb hydride was prepared by ball milling a mixture of MgH 2 and 1 mol.% NbF 5 . This NbH-catalyzed MgH 2 desorbed 6.3 wt.% H 2 in 15 min and absorbed more than 90% of its initial hydrogen capacity within 5 min at 573 K. Moreover, this fast sorption kinetics was maintained after 10 cycles.
Magnesium hydride (MgH 2) was supplied by Sigma-Aldrich and submitted to ball milling with tungsten carbide balls under H 2 atmosphere for 24 hours at 300 rpm using a Fritsch P-6 planetary mill. After that, the MgH 2 was milled for 20 minutes more with 5 …
Comparison between the metal hydride mixtures, LiBH 4 + ½ ZnCl 2 ball milled for 20 minutes shows greater hydrogen release at lower temperatures than the sample, 2LiBH 4 + ZnCl 2 hand mixed for 10 minutes, which emphasize the need of mechanical milling to complete the reaction stated in Eq. (3).
PRODUCED BY BALL MILLING R.A. VARIN1,T. CZUJKO1,3, ... hydride having various grain (crystallite) and powder particle sizes. MgH 2 hydride was also mixed with 5 wt% of n-Ni
The invention relates to a mechanical ball milling method for producing iron nitride magnetic powder. The method using ball milling and nitriding includes: selecting iron powder 2-80 Mum in average particle size as a raw material, placing the iron powder into a ball milling tank, selecting a ball-material ratio to be 10:1-50:1, charging nitrogen 0.1-0.5 Mpa, or selecting ammonia …
MgH 2 and Ti were milled by means of ball milling and Mg-Ti-H hydride phases with a face centered cubic (FCC) structure were successfully synthesized. The Mg-Ti-H FCC hydride phases synthesized had chemical formulae of Mg 40 Ti 60 H 113 and Mg 29 Ti 71 H 57.The hydrogen contents of the Mg 40 Ti 60 H 113 and Mg 29 Ti 71 H 57 FCC hydride phases corresponded …
The ball milling was conducted at 500 rpm for 24 h in the milling jar filled with 50 atm H 2 at the ball-to-sample weight ratio of approximately 120 : 1. The doping amounts of NP-TiH 2 @G were set to be, 1, 3, 5, 7, and 9 wt%.
In the carbon fragments produced from ball milling during preparation, unhybridized π electrons are delocalized and then interact with hydrogen appropriately (Wu and Cheng, 2010). However, fullerenes or CNTs have an inherent spatial structure, so that their properties can only be adjusted using physical approaches like ball milling.
A scanning electron micrograph of another commonly used high temperature metal hydride, MgH2, after ball milling is shown in 2. The surface and morphology of Mg particles after milling were rough and irregular. SEM observation showed small catalyst particle clusters covering larger Mg particles after milling. The surface area and effective ...
Novel hydrides are produced by mechanically alloying at least two different hydrides, preferably at least one simple alkali metal hydride and at least one complex alkali metal hydride such as an alkali metal aluminum hydride; the method of production is simple and can be carried out at room temperature; the novel hydrides are useful as a source of hydrogen and have the particular …
Magnesium hydride undergoes a reversible conversion reaction and it has very good theoretical performances, ... The purpose of our study is to investigate the MgH 2 redox activity by evaluating the effect of ball milling pre-treatments and by studying the conversion reaction mechanism. Three materials, ...
MgH2 (i.e. before ball milling). The present article reports further studies on ball milled magnesium hydride samples. Magnesium hydride crystalizes in a rutile-type structure with spacegroup P42/mmm. MgH2 transforms in an or-thogonal -phase ( -PbO2-type structure) at high temper-atures and pressures [8]. In ball milled samples this phase is
hydride alloy material for an improved Ni/MH, cell. Preparation technique of the alloys as well as its composition has been reported to affect the ... ingots, mechanical alloying (ball-milling), and atomization techniques. Arc-melting technique was studied at BNL, mechanical alloying at LANL, and the pulverization and atomization techniques at ...
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