| Hydrogen Sorption of Pure Mg and Niobium (V) Fluoride-Added Mg Alloys Prepared by Planetary Ball Milling in Hydrogen |
| Hye Ryoung Park1, Young Jun Kwak2, Seong Ho Lee2, Myoung Youp Song3 |
1School of Chemical Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
2Department of Materials Engineering, Graduate School, Chonbuk National University, Jeonju 54896, Republic of Korea
3Division of Advanced Materials Engineering, Hydrogen & Fuel Cell Research Center, Engineering Research Institute, Chonbuk National University, Jeonju 54896, Republic of Korea |
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Received: 5 April 2016; Accepted: 27 June 2016. Published online: 5 December 2016. |
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| ABSTRACT |
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In this work, niobium (V) fluoride was selected as an additive to heighten the hydrogen sorption rates of Mg. Specimens of pure Mg, 5 wt% niobium fluoride－added Mg, and 10 wt% niobium fluoride-added Mg were prepared by planetary ball milling in hydrogen. The hydrogen sorption properties of the specimens were then examined. An Mg－based hydrogen－storage alloy with an effective hydrogen-storage capacity of about 5.5 wt% was developed. At 593 K in 12 bar hydrogen at the first cycle (Cn = 1), the 5 wt% niobium fluoride－added Mg stored 4.37 wt% hydrogen in 5 min and 5.50 wt% hydrogen in 30 min. At 593 K in 1.0 bar hydrogen at Cn = 1, the 5 wt% niobium fluoride－added Mg released 2.11 wt% hydrogen in 10 min, 4.66 wt% hydrogen in 30 min, and 5.43 wt% hydrogen in 60 min. The planetary ball milling of Mg with NbF5 in hydrogen, which generated MgF2, NbH2, and NbF3, is believed to have produced imperfections both on the surface and in the interior of the Mg particles, created clean surfaces, and diminished the particle size of the Mg. The 5 wt% niobium fluoride－added Mg specimen stored a larger quantity of hydrogen in 30 min and a larger quantity of hydrogen was released in 60 min compared with the 10 wt% niobium fluoride－added Mg, or the pure Mg. |
| Keywords:
hydrogen absorbing materials, mechanical milling, microstructure, X-ray diffraction, niobium (V) fluoride-added Mg alloys |
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