|
Vol.52, No.11, 957 ~ 963, 2014
|
| Title |
| Review Paper : Hydriding and Dehydriding Reactions of Mg-xTaF5 (x=0, 5, and 10) Prepared via Reactive Mechanical Grinding |
| Young Jun Kwak , Seong Ho Lee , Hye Ryoung Park , Myoung Youp Song |
|
|
|
| Abstract |
| In this work, TaF5 was chosen as an additive to enhance the hydriding and dehydriding rates of Mg. Samples with the compositions of Mg-x wt% TaF5 (x=0, 5, and 10) were prepared by reactive mechanical grinding. The hydriding and dehydriding properties of the samples were then examined. At 593 K under 12 bar H2 at the first cycle, Mg-5TaF5 absorbed 3.24 wt% H for 2.5 min, 3.95 wt% H for 5 min, 4.50 wt% H for 10 min, and 5.00 wt% H for 30 min. At 593 K under 1.0 bar H2 at the first cycle, Mg-5TaF5 desorbed 0 wt% H for 2.5 min, 0.61 wt% H for 5 min, 1.58 wt% H for 10 min, 3.82 wt% H for 30 min, and 4.93 wt% H for 60 min. Mg-5TaF5 has an effective hydrogen storage capacity of larger than 5 wt%. The reactive mechanical grinding of Mg with TaF5, which formed MgF2 and Ta2H by the reaction of 10Mg + 4TaF5 + H2 → 10MgF2 + 2Ta2H, is believed to facilitate nucleation and reduce the diffusion distances of hydrogen atoms. A higher hydriding rate and larger quantity of hydrogen desorbed for 60 min of Mg-5TaF5 than of Mg-10TaF5 suggest that these effects are stronger in Mg-5TaF5 than in Mg-10TaF5. (Received November 5, 2013) |
|
|
| Key Words |
| hydrogen absorbing materials, mechanical alloying/milling, microstructure, X-ray diffraction, Mg-x wt% TaF5 |
|
|
 |
|
