MgH2 as dopant for improved activation of commercial Mg ingot

• Published in: Journal of alloys and compounds Vol. 575; pp. 364 - 369
• Main Authors: Jain, P., Lang, J., Skryabina, N.Y., Fruchart, D., Santos, S.F, Binder, K., Klassen, T., Huot, J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2013
• Subjects: Activation; Activation behavior; Ball milling; Cold rolling; Hydrogen embrittlement; Hydrogen storage; Hydrogen storage materials; Magnesium; MgH2 catalytic powder; Plates; Scanning electron microscopy; Severe plastic deformation technique; Hydrogen storage materials; Severe plastic deformation technique; MgH2 catalytic powder; Activation behavior; Magnesium
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2013.05.099

•We propose a simple method to reduce production cost of light weight materials for hydrogen storage applications.•Cheaper Mg ingot rather than expensive MgH2 is used as starting material.•Effect of MgH2 as catalytic powder for improved activation behavior of Mg is demonstrated. In this paper, we propose a method to decrease the activation time (first hydrogenation) of commercial Mg. This new alternative processing route uses a combination of cold rolling and short time ball milling to obtain full hydrogen capacity quickly in the first hydrogenation. As ball milling of ductile materials leads to particle agglomeration, brittle Mg plates produced by repetitive cold rolling were used as starting material. These rolled plates were then ball milled for 30min with and without the addition of 5wt% Mg or MgH2 powders. All the synthesized samples were investigated for hydrogen storage, absorption–desorption behavior and microstructure using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and pressure-composition temperature (PCT) methods. Results showed slow activation behavior for cold rolled Mg plates, which was slightly improved after milling. Further improvement was obtained by adding 5wt% of Mg powder during ball milling. In contrast, when the plates were ball milled with 5wt% of MgH2 powder a drastic improvement in activation behavior was observed with hydrogen capacity reaching up to 6.2wt% in comparison to 2.74wt% for undoped and 3.57wt% for Mg doped samples. These results reveal that ball milling with ductile Mg powder deforms only the surface of Mg plates while brittle MgH2 powders causes fracturing and cracks, increasing the surface area and generating heterogeneous nucleation sites within the bulk material.