• Applied Chemistry for Engineering
• /
• v.1 no.1
• /
• pp.30-34
• /
• 1990

This paper summarizes fundamental research on a metal hydrides for the development of new energy. We made a study of the characteristics of the hydrogen absorption-desorption of $DiNi_5$ alloys. As a result, we found that the maximum amount of the hydrogen absorption of $DiNi_5$ alloys (the maximum in the absorption equilibrium pressure section) was H/M=1.04 at $30^{\circ}C$. The hysteresis was the smallest at $30^{\circ}C$. The capability of the hydrogen absorption-desorption was excellent. The number of cycles of the hydrogen absorption-desorption was about 9000 times at $30^{\circ}C$. We found also that the rate of the hydrogen desorption was the largest at $40^{\circ}C$.

• Transactions of the Korean hydrogen and new energy society
• /
• v.30 no.1
• /
• pp.8-13
• /
• 2019

In order to apply the Sievert's type automatic apparatus to thermal analysis of hydrogen absorbing materials, the Sievert's type automatic apparatus was modified in my laboratory. In this study, an experiment was conducted to see if hydrogen absorption and desorption reactions are possible under near constant pressure (${\pm}0.05atm$) using this device. The hydrogenation and dehydrogenation of the Mg-H system was investigated. And the program was also modified for the kinetics. It was found that it is possible to measure the hydrogen absorption rate under near constant pressure of Mg by using the modified Sievert's type automatic apparatus at 573 K and 598 K. And using this system, the hydrogen desorption rate of Mg hydride under near constant pressure at 623 K was also measurable. However, since the hydrogen desorption rate of Mg hydride is fast at 648 K, the hydrogen desorption reaction did not proceed within a constant pressure range of $0.15{\pm}0.05atm$.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.1
• /
• pp.202-211
• /
• 1995

Heat and hydrogen transfer characteristics have been experimentally investigated for a hydride reaction bed, in which hydride material LaN $i_{4,7}$A $l_{0.3}$ is contained for hydrogen storage. This problem is of particular interest in the design of metal hydride devices such as metal-hydride refrigerators, heat pumps, or metal-hydride storage units. Transient behavior of hydrogen transfer through the hydride materials as well as heat transfer is studied during absorption and desorption processes in detail. The experimental results obtained indicate that the mass flow of the hydrogen is strongly affected by the governing parameters, such as the initial pressure of the reaction bed, absorption or desorption period, and cooling or heating temperature. These mass transfer results are along with the heat transfer rate between hydride materials and heat transfer medium in the reaction bed.d.d.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.3
• /
• pp.238-245
• /
• 2017

Mg-Ni nanoparticles were synthesized by a physical vapor condensation method (DC arc-discharge) in a mixture of argon and hydrogen atmosphere, using compressed mixture of micro powders as the raw materials. The crystal phases, morphology, and microstructures of nanoparticles were analyzed by means of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). It was found that the intermetallic compounds of $Mg_2Ni$ and $Mg_2Ni$ formed with existence of phases of Mg, Ni, and MgO in Mg-Ni nanoparticles. After one cycle of hydrogen absorption/desorption process (activation treatment), Mg-Ni nanoparticles exhibited excellent hydrogen absorption properties. $Mg_2Ni$ phase became the main phase by aphase transformation during the hydrogen treatments. The phenomenon of refinement of grain size in the nanoparticle was also observed after the hydrogen absorption/desorption processes, which was attributed to the effect of volume expansion/shrinkage and subsequent break of nanoparticles. Maximum hydrogen absorption contents are 1.75, 2.21 and 2.77 wt.% at 523, 573 and 623 K, respectively.

• Transactions of the Korean hydrogen and new energy society
• /
• v.4 no.1
• /
• pp.41-50
• /
• 1993

The hydrogen absorption and desorption characteristics of microencapsulated (CFM)$Ni_{4.7}Al_{0.2}Fe_{0.1}$ and $MmNi_4Fe$ powder with Ni and/or Cu by means of chemical plating method have been investigated. Initial hydrogen absorption rate and activation property were increased remarkably by encapsulation and subsequent compacting. Pellets abtained by compacting of Cu-encapsulated fine powder have fairly good strength even after 30 cycles of hydriding and dehydriding. Encapsulated alloy powder and their compacts show a good resistance to degradation by $O_2$ or CO in hydrogen.

• Transactions of the Korean hydrogen and new energy society
• /
• v.12 no.4
• /
• pp.247-255
• /
• 2001

The relation between the deformation and the geometrical shape, and the effect of cold work on the hydrogen absorption behavior in palladium were investigated. The Pd specimens used were plates and wires as cold worked and annealed states. The palladium plates and wires were loaded with hydrogen by electrochemical method. Experimental analyses were carried out through X -ray diffraction, micrometer measurement and decimal balance measurement. As the results, it is found that the effect of cold work on hydrogen absorption capacity was relatively small. The deformation of the palladium plates in thickness direction is larger than in other lateral directions whereas the palladium wires showed the same deformation ratio in all radius directions because of the circular distribution of coexisting $\alpha$ and $\beta$ phases. The products of plastic deformation such as slip lines and voids etc. were observed abundantly in all specimens although the specimens had undergone only once of a hydrogen absorption and desorption.

• Transactions of the Korean hydrogen and new energy society
• /
• v.15 no.3
• /
• pp.250-256
• /
• 2004

Magnesium and its alloys have the high potential as hydrogen storage materials because of their highest hydrogen storage capacity, low density and abundant resources. But poor kinetic properties of hydriding and dehydriding and high working temperature have limited their practical applications. In this study, the Mg-Ni binary alloys with different amount of Ni were produced by gravity casting and characterized in order to investigate the relationship between the microstructures and hydriding properties. The maximum hydrogen absorption capacity decreased, but the absorption kinetics increased with Ni content. The difference in the absorption kinetics was resulted from the differences in the sort and shape of primary solid phases and eutectic microstructure.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.861-864
• /
• 2002

Deformation of the specimen was investigated on hydrogen absorption-desorption cycling. In order to study this problem, the cold rolled palladium thin plate as the specimen had been used. By using the electrochemical method, the palladium plate specimen was cyclically hydrogenated in the 0.1 mol $H_2SO_4$ electrolyte. As results, it is noted that the thickness of the plate specimen gradually increased in increasing hydrogenation cycles whereas the width and the length decreased. Also, grains in the plate specimen were greatly deformed after hydrogenation cycling. But hydrogen absorption rate scarcely changed.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.829-832
• /
• 2002

Deformation of the specimens was investigated on hydrogen absorption-desorption cycling. In order to study this problem, the cold rolled and the annealed palladium thin plate as specimens had been used. By using the electrochemical method, the palladium plate specimens were cyclically hydrogenated in the 0.1mol $H_2SO_4$ electrolyte. As results, it is noted that the thickness of the plate specimens gradually increased in increasing hydrogenation cycles whereas the width and the length decreased. Also, Deformation of the cold rolled palladium specimen was lager than the annealed palladium specimen. And grains in the plate specimen were greatly deformed after hydrogenation cycling. But hydrogen absorption rate scarcely changed.

• Transactions of the Korean hydrogen and new energy society
• /
• v.18 no.3
• /
• pp.256-264
• /
• 2007

In order to calculate the relation between the hydrogen and the hydrogen absorption metals in the atomic level, Embedded Atom Method(EAM) is recommended. In this study, we had constructed the EAM programs from constitutive formulas and parameters of the hydrogen and palladium for the purpose of predicting the expansion behavior on hydrogen absorbing in the geometric shape of hydrogen absorption metals, as palladium bars and plates. And the EAM analyses data were compared with the experiment data by using electrochemical method. As results, it is note that the expansion rate in thickness of the palladium plate model by EAM analyses is about 4 times larger than width and length, be similar to experiment results. Also, in the microscopic and macroscopic level the expansion behavior through EAM analyses show good agreement with experiment data.