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Myoung Youp Song - One of the best experts on this subject based on the ideXlab platform.

  • Hydriding and dehydriding rates of Mg, Mg-10TaF5, and Mg-10NbF5 prepared via reactive Mechanical Grinding
    Metals and Materials International, 2015
    Co-Authors: Myoung Youp Song, Young Jun Kwak, Hye Ryoung Park
    Abstract:

    In this work, TaF5 and NbF5 were chosen as additives to enhance the hydriding and dehydriding rates of Mg. Mg, Mg-10TaF5, and Mg-10NbF5 samples were prepared by reactive Mechanical Grinding. The hydriding and dehydriding properties of the samples were then examined. Mg-10TaF5 had the largest amount of hydrogen absorbed for 30 min and the highest initial dehydriding rate after incubation period, followed in order by Mg-10NbF5, and Mg. At 593 K under 12 bar H2 at the first cycle, Mg-10TaF5 absorbed 3.63 wt% H for 5 min and 4.53 wt% H for 30 min. At 593 K under 1.0 bar H2 at the first cycle, Mg-10TaF5 desorbed 0 wt% H for 2.5 min, 0.59 wt% H for 5 min, 3.42 wt% H for 30 min, and 4.24 wt% H for 60 min. The reactive Mechanical Grinding of Mg with TaF5 or NbF5 is believed to have facilitated the nucleation and to have decreased the diffusion distances of hydrogen atoms. These two effects are believed to have increased the hydriding and dehydriding rates of Mg. The MgF2 and Ta2H formed in Mg-10TaF5, and the MgF2, NbH2, and NbF3 formed in Mg-10NbF5 are considered to have enhanced both of these effects.

  • Hydriding and dehydriding rates and hydrogen-storage capacity of Mg–14Ni–3Fe2O3–3Ti prepared by reactive Mechanical Grinding
    Bulletin of Materials Science, 2013
    Co-Authors: Myoung Youp Song, Young Jun Kwak, Hye Ryoung Park, Byoung-goan Kim
    Abstract:

    The magnesium prepared by Mechanical Grinding under H2 (reactive Mechanical Grinding) with transition elements or oxides showed relatively high hydriding and dehydriding rates when the content of additives was about 20 wt%. Ni (expected to increase hydriding and dehydriding rates) was chosen as transition element to be added. Fe2O3 (expected to increase hydriding rate) was selected as an oxide to be added. Ti was also selected since, it was considered to increase the hydriding and dehydriding rates by forming Ti hydride. A sample, Mg–14Ni–3Fe2O3–3Ti, was prepared by reactive Mechanical Grinding and its hydrogen storage properties were investigated. This sample absorbed 4·02 wt% H for 5 min, 4·15 wt% H for 10 min and 4·42 wt% H for 60 min at n = 2. It desorbed 2·46 wt% H for 10 min, 3·98 wt% H for 30 min and 4·20 wt% H for 60 min at n = 2.

  • Improvement of hydrogen-storage properties of MgH2 by addition of Ni and Ti via reactive Mechanical Grinding and a rate-controlling step in its dehydriding reaction
    Metals and Materials International, 2013
    Co-Authors: Myoung Youp Song, Young Jun Kwak, Hye Ryoung Park, Seong Ho Lee, Byoung-goan Kim
    Abstract:

    In a shift from prior work, MgH2, instead of Mg, was used as a starting material in this work. A sample with a composition of 86 wt% MgH2-10 wt% Ni-4 wt% Ti was prepared by reactive Mechanical Grinding. Activation of the sample was completed after the first hydriding cycle. The effects of reactive Mechanical Grinding of Mg with Ni and Ti were discussed. The formation of Mg2Ni increased the hydriding and dehydriding rates of the sample. The addition of Ti increased the hydriding rate and greatly increased the dehydriding rate of the sample. The titanium hydride, TiH1.924, was formed during reactive Mechanical Grinding. This titanium hydride, which is brittle, is thought to help the mixture pulverized by being pulverized during reactive Mechanical Grinding and further to prevent agglomeration of the magnesium by staying as a hydride among Mg particles. A rate-controlling step for the dehydriding reaction of the hydrided MgH2-10Ni-4Ti was analyzed by using a spherical moving boundary model on an assumption that particles have a spherical shape with a uniform diameter.

  • Formation of a High Pressure Form of Magnesium Hydride γ-MgH2 by Mechanical Grinding under Low Hydrogen Pressure
    2013
    Co-Authors: Myoung Youp Song, Young Jun Kwak, Seong Ho Lee, Hye Ryoung Park
    Abstract:

    In order to investigate the formation of a high pressure form of magnesium hydride, γ-MgH2, X-ray diffraction patterns before and after the hydriding reaction were obtained for samples of MgH2, MgH2 after reactive Mechanical Grinding (RMG), and 94 wt% MgH2-6 wt% Ni after reactive Mechanical Grinding. In addition, absorbed hydrogen quantity versus time curves at the first cycle were examined. The MgH2 sample did not contain γ-MgH2. However, the MgH2 after RMG and the 94 wt% MgH2-6 wt% Ni after RMG contained γ-MgH2. All these results prove that after reactive Mechanical Grinding, γ-MgH2, one of the high pressure forms of MgH2, was formed in the MgH2 and 94 wt% MgH2-6 wt% Ni samples under low hydrogen pressures.

  • Formation of Mg(OH)2 in Mg–Ni–Fe2O3 alloys prepared using reactive Mechanical Grinding
    Journal of Industrial and Engineering Chemistry, 2012
    Co-Authors: Myoung Youp Song, Hye Ryoung Park, Sung Hwan Baek, Seong-hyeon Hong
    Abstract:

    Abstract Nickel and purchased Fe2O3 or Fe2O3 synthesized by spray conversion were added to Mg via reactive Mechanical Grinding (Mechanical Grinding in H2). Samples with compositions of 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe2O3 (purchased) and 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe2O3 (synthesized by spray conversion) were prepared, and the phase changes in the samples were examined using X-ray diffraction analysis following hydriding–dehydriding cycling, as well as following reactive Mechanical Grinding. Both samples contained an Mg(OH)2 phase after hydriding–dehydriding cycling, as well as after reactive Mechanical Grinding. To the best of our knowledge, the formation of Mg(OH)2 phase is not reported in Mg-Ni-Fe2O3 system hydrogen storage materials.

Seong-hyeon Hong - One of the best experts on this subject based on the ideXlab platform.

  • Formation of Mg(OH)2 in Mg–Ni–Fe2O3 alloys prepared using reactive Mechanical Grinding
    Journal of Industrial and Engineering Chemistry, 2012
    Co-Authors: Myoung Youp Song, Hye Ryoung Park, Sung Hwan Baek, Seong-hyeon Hong
    Abstract:

    Abstract Nickel and purchased Fe2O3 or Fe2O3 synthesized by spray conversion were added to Mg via reactive Mechanical Grinding (Mechanical Grinding in H2). Samples with compositions of 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe2O3 (purchased) and 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe2O3 (synthesized by spray conversion) were prepared, and the phase changes in the samples were examined using X-ray diffraction analysis following hydriding–dehydriding cycling, as well as following reactive Mechanical Grinding. Both samples contained an Mg(OH)2 phase after hydriding–dehydriding cycling, as well as after reactive Mechanical Grinding. To the best of our knowledge, the formation of Mg(OH)2 phase is not reported in Mg-Ni-Fe2O3 system hydrogen storage materials.

  • Amelioration of the reaction kinetics of Mg with hydrogen by reactive Mechanical Grinding with Ni, Fe2O3, Ti or Fe
    Journal of Industrial and Engineering Chemistry, 2011
    Co-Authors: Myoung Youp Song, Young Jun Kwak, Hye Ryoung Park, Seong-hyeon Hong
    Abstract:

    Abstract The magnesium prepared by Mechanical Grinding under H 2 (reactive Mechanical Grinding) with transition elements or oxides showed relatively high hydriding and dehydriding rates when the content of additives was about 20 wt%. Ni and Fe were chosen as transition elements to be added. Ti was also selected since it was considered to increase the hydriding and dehydriding rates by forming Ti hydride. Samples Mg–14Ni–6Fe 2 O 3 , Mg–14Ni–6Ti, Mg–14Ni–3Fe 2 O 3 –3Ti, and Mg–14Ni–2Fe 2 O 3 –2Ti–2Fe were prepared by reactive Mechanical Grinding, and their hydrogen storage properties were examined. Among these samples, Mg–14Ni–6Ti had the highest hydriding and dehydriding rates.

  • Hydrogen-storage performance of an Mg–Ni–Fe alloy prepared by reactive Mechanical Grinding
    Journal of Materials Science, 2009
    Co-Authors: Myoung Youp Song, Jean-louis Bobet, Sung Hwan Baek, Sung-nam Kwon, Seong-hyeon Hong
    Abstract:

    The 71.5%Mg–23.5%Ni–5%Fe alloy prepared by reactive Mechanical Grinding for 4 h does not need activation. The activated sample has the hydriding rate of 0.494 wt%/min for 5 min and absorbs 3.32 wt% for 60 min at 593 K under 1.2 MPa H_2. It has the dehydriding rate of 0.330 wt%/min for 5 min and desorbs 2.42 wt%H for 20 min at 593 K 0.1 MPa H_2. The XRD pattern of 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe after reactive Mechanical Grinding exhibits MgH_2 in addition to starting elements Mg, Ni, and Fe. 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe after hydriding–dehydriding cycling contains Mg, Mg_2Ni, MgO, and Fe. The reactive Mechanical Grinding of Mg with Ni and Fe is considered to facilitate nucleation by creating many defects on the surface and in the interior of Mg, by the additive acting as active sites for the nucleation and shorten diffusion distances of hydrogen atoms by reducing the particle size of Mg. The MgH_2 formed in the as-milled 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe alloy is considered to lead to the creation of more defects and finer particle size.

  • Enhancement of the hydrogen storage characteristics of Mg by reactive Mechanical Grinding with Ni, Fe and Ti
    International Journal of Hydrogen Energy, 2008
    Co-Authors: Sung-nam Kwon, Seong-hyeon Hong, Sung Hwan Baek, Daniel R. Mumm, Myoung Youp Song
    Abstract:

    Abstract Mg-10wt%Ni-5wt%Fe-5wt%Ti powder was prepared by reactive Mechanical Grinding using a planetary ball mill. The Mg-10wt%Ni-5wt%Fe-5wt%Ti powder exhibited high hydriding and dehydriding rates even at the first cycle, and its activation was completed after two hydriding–dehydriding cycles. After the reactive Mechanical Grinding, the particle size of the powder was reduced, as compared with those of the starting materials. The hydrogen storage properties were measured at temperatures of 473 K, 573 K and 623 K. The activated Mg-10wt%Ni-5wt%Fe-5wt%Ti powder absorbed 5.31 wt% and 5.51 wt% of hydrogen for 5 min and 1 h, respectively, at 573 K under 12 bar H2. It desorbed 5.18 wt% of hydrogen at 573 K under 1.0 bar H2 for 1 h. The initial hydrogen absorption rate increased when passing from 473 K to 573 K, but decreased at 623 K. The hydrogen desorption rate increased rapidly with increasing temperature from 473 K to 623 K. The hydrogen storage capacity was about 6.72 wt% at 573 K.

  • Development of Mg-oxide-Ni hydrogen-storage alloys by reactive Mechanical Grinding
    International Journal of Hydrogen Energy, 2007
    Co-Authors: Myoung Youp Song, Sung-nam Kwon, Daniel R. Mumm, Seong-hyeon Hong
    Abstract:

    Abstract Mg-oxide and Mg-oxide–Ni hydrogen storage alloys were prepared by Mechanical Grinding under H 2 (reactive Mechanical Grinding). Among these alloys, Mg – ( 7.5 wt % Fe 2 O 3 , 7.5 wt%Ni) prepared by Grinding for 4 h with nano-structured Fe 2 O 3 particles and Ni showed the best hydrogen storage properties. The as-milled sample absorbed 4.75 wt% H at 593 K under 12 bar H 2 for 60 min. Its activation was accomplished after two hydriding–dehydriding cycles. The activated sample absorbed 4.36 wt% H at 593 K under 12 bar H 2 for 60 min and desorbed 4.26 wt% H at 593 K under 1.0 bar H 2 for 60 min. After hydriding–dehydriding cycling, Mg 2 Ni , Fe and MgO are formed. The large bar-like hydrided particles have round and expanding surfaces, suggesting that they expanded during the hydriding reaction, while the dehydrided particles exhibit contracted surfaces with wrinkles.

Jong-soo Bae - One of the best experts on this subject based on the ideXlab platform.

  • Improvement of hydrogen-sorption characteristics of Mg by reactive Mechanical Grinding with Cr2O3 prepared by spray conversion
    International Journal of Hydrogen Energy, 2006
    Co-Authors: Myoung Youp Song, Seong-hyeon Hong, Sung-nam Kwon, Daniel R. Mumm, Jong-soo Bae
    Abstract:

    Abstract Nano-structured Cr 2 O 3 powder could be produced by spray conversion (spray drying of an aqueous of Cr nitrate, oxidation and milling). The samples Mg—10 wt% Cr 2 O 3 using nano-structured Cr 2 O 3 synthesized by spray conversion were prepared by Mechanical Grinding under H 2 (reactive Mechanical Grinding) under the optimum conditions, previously studied, for the preparation of the sample Mg—10 wt% Fe 2 O 3 using purchased Fe 2 O 3 . The sample Mg—10 wt% Cr 2 O 3 as milled absorbed 4.48 wt% H 2 at 593 K under 12 bar H 2 for 60 min. Its activation was accomplished after two hydriding–dehydriding cycles. The activated sample absorbed 5.48 wt% H 2 for 10 min and 5.93 wt% H 2 for 60 min at 593 K, 12 bar H 2 , and desorbed 3.65 wt% H 2 at 603 K, 1.0 bar H 2 for 60 min. H 2 -storage capacity was 6.38 wt% under 12 bar H 2 at 593 K (from P–C-T curve). Reactive Mechanical Grinding of Mg with Cr 2 O 3 by spray conversion increased the hydriding rate effectively but increased a little the dehydriding rate, compared with reactive Mechanical Grinding of Mg with Fe 2 O 3 purchased, Fe 2 O 3 by spray conversion, MnO and SiO 2 by spray conversion.

  • Hydrogen-storage properties of Mg–oxide alloys prepared by reactive Mechanical Grinding
    Journal of Alloys and Compounds, 2005
    Co-Authors: Myoung Youp Song, Seong-hyeon Hong, Ikhyun Kwon, Sung-nam Kwon, Chan-gi Park, Jong-soo Bae, Daniel R. Mumm
    Abstract:

    Abstract The samples Mg–10 wt.% M (M = Fe 2 O 3 purchased, Fe 2 O 3 by spray conversion, MnO purchased, and SiO 2 by spray conversion) were prepared by Mechanical Grinding under H 2 (reactive Mechanical Grinding) under the optimum conditions for the preparation of the sample Mg–10 wt.% Fe 2 O 3 using purchased Fe 2 O 3 . The activated Mg–10 wt.% Fe 2 O 3 by spray conversion has the highest hydriding rate ( H a  = 5.55 wt.% at 593 K, 12 bar H 2 for 60 min) of all the samples. The activated Mg–10 wt.% MnO has the highest dehydriding rate ( H d  = 1.94 wt.% at 593 K, 1.0 bar H 2 for 60 min). The equilibrium plateau pressure is about 1.5 bar H 2 . The effects of reactive Mechanical Grinding and hydriding–dehydriding cycling on the hydrogen properties of Mg were discussed.

  • Improvement of hydrogen-storage properties of Mg by reactive Mechanical Grinding with Fe2O3 prepared by spray conversion
    Journal of Alloys and Compounds, 2005
    Co-Authors: Myoung Youp Song, Seong-hyeon Hong, Ikhyun Kwon, Sung-nam Kwon, Chan-gi Park, Jong-soo Bae
    Abstract:

    Abstract Samples of Mg–10 wt.%Fe 2 O 3 using nano-structured Fe 2 O 3 synthesized by spray conversion were prepared by Mechanical Grinding under H 2 (reactive Mechanical Grinding) under the optimum conditions for the preparation of the sample Mg–10 wt.%Fe 2 O 3 using purchased Fe 2 O 3 . The sample Mg–10 wt.%Fe 2 O 3 as milled absorbed 3.87 wt.% hydrogen at 593 K under 12 bar H 2 for 60 min. Its activation was accomplished after two hydriding–dehydriding cycles. The activated sample absorbed 5.55 wt.% hydrogen at 593 K, 12 bar H 2 for 60 min. Hydrogen-storage capacity is 6.67 wt.% under 12 bar H 2 at 593 K (from P – C – T curve). The effects of reactive Mechanical Grinding and hydriding–dehydriding cycling on the hydrogen properties of Mg were discussed.

  • Improvement of hydrogen-storage properties of Mg by reactive Mechanical Grinding with Fe2O3
    Journal of Alloys and Compounds, 2005
    Co-Authors: Ikhyun Kwon, Jean-louis Bobet, Jong-soo Bae, Myoung Youp Song
    Abstract:

    We tried to improve the H2-sorption properties of Mg by Mechanical Grinding under H2 (reactive Mechanical Grinding) with Fe2O3 under various milling conditions. The sample Mg–10 wt.%Fe2O3 prepared by milling at a revolution speed of 250 rpm for 24 h has the best hydrogen-storage properties. It absorbs 5.05 wt.% hydrogen at 593 K under 12 bar H2 for 60 min at the first cycle. Its activation is accomplished after three hydriding–dehydriding cycles. The activated sample absorbs 4.22 wt.% hydrogen at 593 K, 12 bar H2 for 10 min. The reactive Grinding of Mg with Fe2O3 increases the H2-sorption rates by facilitating nucleation (by creating defects on the surface of the Mg particles and by the additive), by making cracks on the surface of Mg particles and reducing the particle size of Mg and thus by shortening the diffusion distances of hydrogen atoms. Hydriding–dehydriding cycling also increases the H2-sorption rates by creating defects on the surface of the Mg particles, and by making cracks on the surface of Mg particles and reducing the particle size of Mg.

  • Development of hydrogen-storage alloys of Mg–Fe2O3 system by reactive Mechanical Grinding
    International Journal of Hydrogen Energy, 2005
    Co-Authors: Myoung Youp Song, Ikhyun Kwon, Jong-soo Bae
    Abstract:

    Abstract We have improved the H 2 -sorption properties of Mg by Mechanical Grinding under H 2 (reactive Mechanical Grinding) with Fe 2 O 3 . The sample Mg–10 wt% Fe 2 O 3 prepared by milling at the revolution speed of 250 rpm for 6 h has the best hydrogen-storage properties. It absorbs 3.43 wt% hydrogen at the first cycle at 593 K under 12 bar H 2 for 60 min. Its activation is accomplished after three hydriding–dehydriding cycles. The activated sample absorbs 3.32 wt% hydrogen at 593 K, 12 bar H 2 for 60 min. The reactive Grinding of Mg with Fe 2 O 3 increases the H 2 -sorption rates by facilitating nucleation (by creating defects on the surface of the Mg particles and by the additive) by making cracks on the surface of Mg particles and reducing the particle size of Mg and thus by shortening the diffusion distances of hydrogen atoms. Hydriding–dehydriding cycling increases the H 2 -sorption rates by making cracks on the surface of Mg particles and reducing the particle size of Mg. The agglomeration of the particles resulting from the annealing effect during cycling decreases the hydriding and dehydriding rates.

Sung-nam Kwon - One of the best experts on this subject based on the ideXlab platform.

  • Hydrogen-storage performance of an Mg–Ni–Fe alloy prepared by reactive Mechanical Grinding
    Journal of Materials Science, 2009
    Co-Authors: Myoung Youp Song, Jean-louis Bobet, Sung Hwan Baek, Sung-nam Kwon, Seong-hyeon Hong
    Abstract:

    The 71.5%Mg–23.5%Ni–5%Fe alloy prepared by reactive Mechanical Grinding for 4 h does not need activation. The activated sample has the hydriding rate of 0.494 wt%/min for 5 min and absorbs 3.32 wt% for 60 min at 593 K under 1.2 MPa H_2. It has the dehydriding rate of 0.330 wt%/min for 5 min and desorbs 2.42 wt%H for 20 min at 593 K 0.1 MPa H_2. The XRD pattern of 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe after reactive Mechanical Grinding exhibits MgH_2 in addition to starting elements Mg, Ni, and Fe. 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe after hydriding–dehydriding cycling contains Mg, Mg_2Ni, MgO, and Fe. The reactive Mechanical Grinding of Mg with Ni and Fe is considered to facilitate nucleation by creating many defects on the surface and in the interior of Mg, by the additive acting as active sites for the nucleation and shorten diffusion distances of hydrogen atoms by reducing the particle size of Mg. The MgH_2 formed in the as-milled 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe alloy is considered to lead to the creation of more defects and finer particle size.

  • Enhancement of the hydrogen storage characteristics of Mg by reactive Mechanical Grinding with Ni, Fe and Ti
    International Journal of Hydrogen Energy, 2008
    Co-Authors: Sung-nam Kwon, Seong-hyeon Hong, Sung Hwan Baek, Daniel R. Mumm, Myoung Youp Song
    Abstract:

    Abstract Mg-10wt%Ni-5wt%Fe-5wt%Ti powder was prepared by reactive Mechanical Grinding using a planetary ball mill. The Mg-10wt%Ni-5wt%Fe-5wt%Ti powder exhibited high hydriding and dehydriding rates even at the first cycle, and its activation was completed after two hydriding–dehydriding cycles. After the reactive Mechanical Grinding, the particle size of the powder was reduced, as compared with those of the starting materials. The hydrogen storage properties were measured at temperatures of 473 K, 573 K and 623 K. The activated Mg-10wt%Ni-5wt%Fe-5wt%Ti powder absorbed 5.31 wt% and 5.51 wt% of hydrogen for 5 min and 1 h, respectively, at 573 K under 12 bar H2. It desorbed 5.18 wt% of hydrogen at 573 K under 1.0 bar H2 for 1 h. The initial hydrogen absorption rate increased when passing from 473 K to 573 K, but decreased at 623 K. The hydrogen desorption rate increased rapidly with increasing temperature from 473 K to 623 K. The hydrogen storage capacity was about 6.72 wt% at 573 K.

  • Development of Mg-oxide-Ni hydrogen-storage alloys by reactive Mechanical Grinding
    International Journal of Hydrogen Energy, 2007
    Co-Authors: Myoung Youp Song, Sung-nam Kwon, Daniel R. Mumm, Seong-hyeon Hong
    Abstract:

    Abstract Mg-oxide and Mg-oxide–Ni hydrogen storage alloys were prepared by Mechanical Grinding under H 2 (reactive Mechanical Grinding). Among these alloys, Mg – ( 7.5 wt % Fe 2 O 3 , 7.5 wt%Ni) prepared by Grinding for 4 h with nano-structured Fe 2 O 3 particles and Ni showed the best hydrogen storage properties. The as-milled sample absorbed 4.75 wt% H at 593 K under 12 bar H 2 for 60 min. Its activation was accomplished after two hydriding–dehydriding cycles. The activated sample absorbed 4.36 wt% H at 593 K under 12 bar H 2 for 60 min and desorbed 4.26 wt% H at 593 K under 1.0 bar H 2 for 60 min. After hydriding–dehydriding cycling, Mg 2 Ni , Fe and MgO are formed. The large bar-like hydrided particles have round and expanding surfaces, suggesting that they expanded during the hydriding reaction, while the dehydrided particles exhibit contracted surfaces with wrinkles.

  • Improvement of hydrogen-sorption characteristics of Mg by reactive Mechanical Grinding with Cr2O3 prepared by spray conversion
    International Journal of Hydrogen Energy, 2006
    Co-Authors: Myoung Youp Song, Seong-hyeon Hong, Sung-nam Kwon, Daniel R. Mumm, Jong-soo Bae
    Abstract:

    Abstract Nano-structured Cr 2 O 3 powder could be produced by spray conversion (spray drying of an aqueous of Cr nitrate, oxidation and milling). The samples Mg—10 wt% Cr 2 O 3 using nano-structured Cr 2 O 3 synthesized by spray conversion were prepared by Mechanical Grinding under H 2 (reactive Mechanical Grinding) under the optimum conditions, previously studied, for the preparation of the sample Mg—10 wt% Fe 2 O 3 using purchased Fe 2 O 3 . The sample Mg—10 wt% Cr 2 O 3 as milled absorbed 4.48 wt% H 2 at 593 K under 12 bar H 2 for 60 min. Its activation was accomplished after two hydriding–dehydriding cycles. The activated sample absorbed 5.48 wt% H 2 for 10 min and 5.93 wt% H 2 for 60 min at 593 K, 12 bar H 2 , and desorbed 3.65 wt% H 2 at 603 K, 1.0 bar H 2 for 60 min. H 2 -storage capacity was 6.38 wt% under 12 bar H 2 at 593 K (from P–C-T curve). Reactive Mechanical Grinding of Mg with Cr 2 O 3 by spray conversion increased the hydriding rate effectively but increased a little the dehydriding rate, compared with reactive Mechanical Grinding of Mg with Fe 2 O 3 purchased, Fe 2 O 3 by spray conversion, MnO and SiO 2 by spray conversion.

  • Hydrogen-storage properties of Mg–oxide alloys prepared by reactive Mechanical Grinding
    Journal of Alloys and Compounds, 2005
    Co-Authors: Myoung Youp Song, Seong-hyeon Hong, Ikhyun Kwon, Sung-nam Kwon, Chan-gi Park, Jong-soo Bae, Daniel R. Mumm
    Abstract:

    Abstract The samples Mg–10 wt.% M (M = Fe 2 O 3 purchased, Fe 2 O 3 by spray conversion, MnO purchased, and SiO 2 by spray conversion) were prepared by Mechanical Grinding under H 2 (reactive Mechanical Grinding) under the optimum conditions for the preparation of the sample Mg–10 wt.% Fe 2 O 3 using purchased Fe 2 O 3 . The activated Mg–10 wt.% Fe 2 O 3 by spray conversion has the highest hydriding rate ( H a  = 5.55 wt.% at 593 K, 12 bar H 2 for 60 min) of all the samples. The activated Mg–10 wt.% MnO has the highest dehydriding rate ( H d  = 1.94 wt.% at 593 K, 1.0 bar H 2 for 60 min). The equilibrium plateau pressure is about 1.5 bar H 2 . The effects of reactive Mechanical Grinding and hydriding–dehydriding cycling on the hydrogen properties of Mg were discussed.

Jean-louis Bobet - One of the best experts on this subject based on the ideXlab platform.

  • Hydrogen-storage performance of an Mg–Ni–Fe alloy prepared by reactive Mechanical Grinding
    Journal of Materials Science, 2009
    Co-Authors: Myoung Youp Song, Jean-louis Bobet, Sung Hwan Baek, Sung-nam Kwon, Seong-hyeon Hong
    Abstract:

    The 71.5%Mg–23.5%Ni–5%Fe alloy prepared by reactive Mechanical Grinding for 4 h does not need activation. The activated sample has the hydriding rate of 0.494 wt%/min for 5 min and absorbs 3.32 wt% for 60 min at 593 K under 1.2 MPa H_2. It has the dehydriding rate of 0.330 wt%/min for 5 min and desorbs 2.42 wt%H for 20 min at 593 K 0.1 MPa H_2. The XRD pattern of 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe after reactive Mechanical Grinding exhibits MgH_2 in addition to starting elements Mg, Ni, and Fe. 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe after hydriding–dehydriding cycling contains Mg, Mg_2Ni, MgO, and Fe. The reactive Mechanical Grinding of Mg with Ni and Fe is considered to facilitate nucleation by creating many defects on the surface and in the interior of Mg, by the additive acting as active sites for the nucleation and shorten diffusion distances of hydrogen atoms by reducing the particle size of Mg. The MgH_2 formed in the as-milled 71.5 wt%Mg–23.5 wt%Ni–5 wt%Fe alloy is considered to lead to the creation of more defects and finer particle size.

  • Magnetocaloric properties of amorphous GdNiAl obtained by Mechanical Grinding
    Applied physics. A Materials science & processing, 2005
    Co-Authors: Bernard Chevalier, Jean-louis Bobet, Jorge Sánchez Marcos, Jesus Rodríguez Fernández, J. C. Gómez Sal
    Abstract:

    An amorphous GdNiAl sample was prepared by Mechanical Grinding performed on a crystallised intermetallic...

  • Improvement of hydrogen-storage properties of Mg by reactive Mechanical Grinding with Fe2O3
    Journal of Alloys and Compounds, 2005
    Co-Authors: Ikhyun Kwon, Jean-louis Bobet, Jong-soo Bae, Myoung Youp Song
    Abstract:

    We tried to improve the H2-sorption properties of Mg by Mechanical Grinding under H2 (reactive Mechanical Grinding) with Fe2O3 under various milling conditions. The sample Mg–10 wt.%Fe2O3 prepared by milling at a revolution speed of 250 rpm for 24 h has the best hydrogen-storage properties. It absorbs 5.05 wt.% hydrogen at 593 K under 12 bar H2 for 60 min at the first cycle. Its activation is accomplished after three hydriding–dehydriding cycles. The activated sample absorbs 4.22 wt.% hydrogen at 593 K, 12 bar H2 for 10 min. The reactive Grinding of Mg with Fe2O3 increases the H2-sorption rates by facilitating nucleation (by creating defects on the surface of the Mg particles and by the additive), by making cracks on the surface of Mg particles and reducing the particle size of Mg and thus by shortening the diffusion distances of hydrogen atoms. Hydriding–dehydriding cycling also increases the H2-sorption rates by creating defects on the surface of the Mg particles, and by making cracks on the surface of Mg particles and reducing the particle size of Mg.

  • Hydrogen storage properties of Mg-based mixtures elaborated by reactive Mechanical Grinding
    Journal of Materials Science, 2004
    Co-Authors: Jean-louis Bobet, Bernard Chevalier
    Abstract:

    The hydrogen sorption properties of Mg + 10 wt% WO3 and Mg + 5 wt% Cr2O3 mixtures made by reactive (under hydrogen) Mechanical Grinding were studied and compared with those of elemental Mg subjected to a similar preparation procedure. It was observed that both oxides have an important catalytic effect on hydrogen absorption and desorption. Moreover, in the case of Cr2O3 addition, both milling speed (i.e, milling energy and milling mode) and ball to powder weight ratio influence drastically the hydrogen sorption kinetics.

  • Hydrogen storage properties of Mg-based mixtures elaborated by reactive Mechanical Grinding
    Journal of Materials Science, 2004
    Co-Authors: Jean-louis Bobet, Bernard Chevalier
    Abstract:

    The hydrogen sorption properties of Mg+10% WO3 and Mg+5% Cr2O3 mixtures made by reactive (under hydrogene) Mechanical Grinding were studied and compared with those of elemental Mg subjected...