• 한국수소및신에너지학회논문집
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• 제18권4호
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• pp.399-405
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• 2007

The hyper-eutectic Mg-33.5%Ni alloy was rapidly solidified by melt spinning process. The melt-spun Mg-33.5%Ni has amorphous structure and crystallization occurred above $162^{\circ}C$. The hydriding and dehydriding rates of melt-spun Mg-33.5%Ni increased with cycle and high rate of hydrogen storage occurred at 3rd cycle. The maximum hydrogen amount absorbed in melt-spun Mg-33.5%Ni at $300^{\circ}C$ is about 4.5%.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.634-640
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• 2011

The effect of cycling on the absorption and desorption characteristics of the 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm system was investigated. The material was made by Hydrogen Combustion Synthesis. The cycling experiment was performed at 298 K, 30 atm for 15 min. During the reaction time, the amount of absorption was fully desorbed. After the full activation, the hydrogen storage capacity was 1.57 wt% and the capacity was maintained until 50 cycles. And the reaction rate does not change with an increase in the number of cycles. This material has good durability and reversible feature.

• 대한금속재료학회지
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• 제50권10호
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• pp.769-774
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• 2012

Mg-x wt% $Fe_2O_3-y$ wt% Ni samples were prepared by reactive mechanical grinding in a planetary ball mill, and their hydrogen-storage properties were investigated and compared. Activations of $Mg-5Fe_2O_3-5Ni$ was completed after one hydriding (under 12 bar $H_2$) - dehydriding (in vacuum) cycle at 593 K. At n = 2, $Mg-5Fe_2O_3-5Ni$ absorbed 3.43 wt% H for 5 min, 3.57 wt% H for 10 min, 3.76 wt% H for 20 min, and 3.98 wt% H for 60 min. Activated $Mg-10Fe_2O_3$ had the highest hydriding rate, absorbing 2.99 wt% H for 2.5 min, 4.86 wt% H for 10 min, and 5.54 wt% H for 60 min at 593 K under 12 bar $H_2$. Activated $Mg-10Fe_2O_3-5Ni$ had the highest dehydriding rate, desorbing 1.31 wt% H for 10 min, 2.91 wt% H for 30 min, and 3.83 wt% H for 60 min at 593 K under 1.0 bar $H_2$.

• 공업화학
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• 제9권2호
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• pp.255-260
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• 1998

금속수소화물 $LaNi_5$와 $LaNi_{4.5}Al_{0.5}$을 화학적 합성법으로 제조하여, 합성된 금속수소화물의 물성을 다양한 방법으로 확인하였다. $LaNi_5$와 $LaNi_{4.5}Al_{0.5}$은 2회 정도 수소화/탈수소화 반응을 시키면 활성화되었으며, 압력-농도-온도 곡선을 측정한 결과 각각 6개와 5.5개의 수소원자가 저장되었다. $LaNi_{4.5}Al_{0.5}$의 경우 수소화 반응속도를 초기속도법으로 구한 결과 비반응 수축핵모델이 잘 적용되었으며, 수소화반응의 율속단계는 $LaNi_{4.5}Al_{0.5}$의 표면에서 수소분자의 해리화학흡착임을 알 수 있었다. $LaNi_{4.5}Al_{0.5}$의 수소화반응 활성화에너지는 $9.506kcal/mol-H_2$이었으며, 반응속도식은 273~343K와 $P_o-P_{eq}=0.25{\sim}0.66atm$의 범위에서 아래와 같이 표시되었다. $\frac{dX}{dt}=4.636(P_o-P_{eq})$ exp$\frac{-9506}{RT}$).

• 한국재료학회지
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• 제23권10호
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• pp.562-567
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• 2013

A 90 wt% Mg-10 wt% $NbF_5$ sample was prepared by mechanical milling under $H_2$ (reactive mechanical grinding). Its hydriding and dehydriding properties were then examined. Activation of the 90 wt% Mg-10 wt% $NbF_5$ sample was not required. At n=1, the sample absorbed 3.11 wt% H for 2.5 min, 3.55 wt% H for 5 min, 3.86 wt% H for 10 min, and 4.23 wt% H for 30 min at 593K under 12 bar $H_2$. At n=1, the sample desorbed 0.17 wt% H for 5 min, 0.74 wt% H for 10 min, 2.03 wt% H for 30 min, and 2.81 wt% H for 60 min at 593K under 1.0 bar $H_2$. The XRD pattern of the 90 wt% Mg-10 wt% $NbF_5$ after reactive mechanical grinding showed Mg, ${\beta}-MgH_2$ and small amounts of ${\gamma}-MgH_2$, $NbH_2$, $MgF_2$ and $NbF_3$. The XRD pattern of the 90 wt% Mg-10 wt% $NbF_5$ dehydrided at n=3 revealed Mg, ${\beta}-MgH_2$, a small amount of MgO and very small amounts of $MgH_2$ and $NbH_2$. The 90 wt% Mg-10 wt% $NbF_5$ had a higher initial hydriding rate and a larger quantity of hydrogen absorbed for 60 min than the 90 wt% Mg-10 wt% MnO and the 90 wt% Mg-10 wt% $Fe_2O_3$, which were reported to have quite high hydriding rates and/or dehydriding rates. The 90 wt% Mg-10 wt% $NbF_5$ had a higher initial dehydriding rate (after an incubation period) and a larger quantity of hydrogen desorbed for 60 min than the 90 wt% Mg-10 wt% MnO and the 90 wt% Mg-10 wt% $Fe_2O_3$.

• 대한금속재료학회지
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• 제50권3호
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• pp.256-262
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• 2012

This study investigated the hydrogen storage properties of Zr-Based $AB_{2-x}M_x$ metal hybride made by HCS (Hydriding Combustion Synthesis). The materials were prepared by HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm, HCS 80 wt% $AB_2$-20 wt% Mg and pure Zr-Based $AB_2$, These materials were activated at 298 K under 20 bar. Both HCS 80 wt% $AB_2$-20 wt% Mg and HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm were absorbed within 1 minute. In the case of the $AB_2$, it was perfectly absorbed within 6 minutes. Then, the materials were evaluated to obtain P-C-T (Pressure-Composition-Temperature) curves at 298K. As a result, the hydrogen storage capacity of HCS 80 wt% $AB_2$-20 wt% Mg, HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm and pure Zr-Based $AB_2$ were determined to be 1.2, 1.6 and 1.74 wt%, respectively. The activation energy and rate controlling step were calculated by the Johnson-Mehl Avrami equation. The activation energies of HCS 80 wt% $AB_2$-20 wt% Mg, HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm and pure Zr-Based $AB_2$ were 26.91, 20.45, and 60.41 kJ/mol, respectively. Also, the values of ${\eta}$ in the Johnson-Mehl Avrami equation for HCS 80 wt% $AB_2$-20 wt% Mg, HCS 80 wt% $AB_2$-15 wt% Mg-5 wt% Mm and pure Zr-Based $AB_2$ are 0.60, 0.51, and 0.44. So, the rate controlling steps which indicate hydrogen storage mechanism are an one dimensional diffusion process.

• 한국수소및신에너지학회논문집
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• 제26권6호
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• pp.541-546
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• 2015

Global energy shortage problem is expected to increase driven by strong energy demand growth from developing countries. Nuclear fusion power offers the prospect of an almost infinite source of energy for future generations. Hydrogen isotope storage and delivery system is a important subsystem of a nuclear fusion fuel cycle. Metal hydride is a method of the high-density storage of hydrogen isotope. For the safety storage of hydrogen isotope, depleted uranium (DU) has been widely proposed. But DU needs a safe test because It is a radioactive substance. The authors studied a small-scale DU bed and a medium-scale DU bed for the safety test. And then we made a large-scale DU bed and stored hydrogen isotopes in the bed. Before the hydriding/dehydriding, we tested it's heating and cooling properties and carried out an activation procedure. As a result, Reaction rate of DU-$H_2$ is more rapid than the other metal hydride ZrCo. Through the successful storage result of our large bed, the development possibility of the hydrogen isotope storage technology seems promising.

• 대한금속재료학회지
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• 제47권7호
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• pp.433-439
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• 2009

Ti and Ti based hydrogen storage alloys have been thought to be the third generation of alloys with a high hydrogen capacity, which makes it difficult to handle because of high reactivity. In order to solve the problem, the activation of a wide range of hysteresis of hydriding/dehydriding and without degradation of hydrogen capacity due to the hydriding/dehydriding cycle have to be improved in order to be aplied. Ti-Cr alloys have a high capacity about 0.8 wt.% in an ambient atmosphere. When the Ti-Cr alloys are added to Nb and Ta elements, they formed a laves phase in the alloy system. The Nb element was expected to make easy diffuse hydrogen in the Ti-Cr storage alloy, which was a catalytic element. In this study, the Ti-Nb-Cr ternary alloy was prepared by melt spinning. As-received specimens were characterized using XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy) with EDX (Energy Dispersive X-ray) and TG/DSC (Thermo Gravimetric Analysis/Differential Scanning Calorimetry). In order to examine hydrogenation behavior, the PCI (Pressure-Composition-Isotherm) was performed at 293, 323, 373 and 423 K.

• 대한금속재료학회지
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• 제50권12호
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• pp.949-953
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• 2012

$MgH_2$ was employed as a starting material instead of Mg in this work. A sample with a composition of 94 wt% $MgH_2-6$ wt% Ni (called $MgH_2-6Ni$) was prepared by reactive mechanical grinding. The hydriding and dehydriding properties were then examined. An $MgH_2-Ni$ hydrogen storage alloy that does not require an activation process was developed. The alloy was prepared in a planetary ball mill by grinding for 4 h at a ball disc revolution speed of 250 rpm under a hydrogen pressure of about 12 bar. The sample absorbed 3.74 wt% H for 5 min, 4.07 wt% H for 10 min, and 4.41 wt% H for 60 min at 573 K under 12 bar $H_2$, and desorbed 0.93 wt% H for 10 min, 1.99 wt% H for 30 min, and 3.16 wt% H for 60 min at 573 K under 1.0 bar $H_2$. $MgH_2-6Ni$ after reactive mechanical grinding contained ${\beta}-MgH_2$ (a room temperature form of $MgH_2$), Ni, ${\gamma}-MgH_2$ (a high pressure form of $MgH_2$), and a very small amount of MgO. Reactive mechanical grinding of Mg with Ni is considered to facilitate nucleation, and to reduce the particle size of Mg. $Mg_2Ni$ formed during reactive mechanical grinding also increases the hydriding and dehydriding rates of the sample.

• 한국수소및신에너지학회논문집
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• 제13권1호
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• pp.13-23
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• 2002

Hydrogenation properties of Mg-Ni and Mg-Ti-Ni alloys were investigated by Pressure-Composition Isotherm (PCI) test. Those alloys were fabricated by a new alloying method, Rotation-Cylinder Method (RCM). The as-cast microstructure of Mg-10 mass% Ni alloy consists of an island-like hydride forming $\alpha$-Mg phase and the eutectic structure. After 350 cyclic tests, Mg-lO mass % Ni alloy was pulverized into fine particles of 100 nm. The fine particles, which have a large specific surface area, are highly reactive with hydrogen. However, extreme pulvehzation can separate Mg from $Mg_2Ni$ in the eutectic structure, so $Mg_2Ni$ of the eutectic structure cannot behave as a dissociated hydrogen supplier.