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M: Metallphysik
M 32: Poster TU B (Symposium Tomographic Methods in Materials Research M-32.32-55)
M 32.2: Poster
Montag, 7. März 2005, 14:30–16:30, Poster TU B
Hydrogen sorption properties of Mg-1wt%Ni-0.2wt%Pd prepared by reactive milling — •O. Gutfleisch1, S. dal Toe1, M. Herrich1, J. Zulkarnain1, A. Handstein1, and A. Pratt2 — 1IFW Dresden, Institut für Metallische Werkstoffe, Helmholtzstr. 20, D01069 Dresden, Germany — 2Johnson Matthey Technology Centre, Reading RG4 9NH, UK
Despite the large differences in melting points and the high vapour pressure of Mg, we succeeded in the preparation of induction-melted Mg-1wt.%Ni-0.2wt%Pd alloy. The alloy was then reactively ball milled in 10 bar hydrogen. The structural changes during milling were characterised by XRD and high resolution scanning electron microscopy. The hydrogen sorption properties have been systematically studied by gravimetric analysis in a wide temperature and pressure range for absorption (1-10 bar, 50-300 ∘C) and desorption (250-350 ∘C, 50 mbar-1 bar). At 300 ∘C, the hydrogen absorption in 10 bar proceeds within less than 5 min reaching 6.3 wt% capacity; desorption in 50 mbar is completed within 10 min, whereas 20 min are needed when desorbing into 1 bar. Absorption conditions have been found to be very moderate: e.g. at 200 ∘C and 4 bar 5.5 wt.% is reached within 5 min, at 150 ∘C and 2 bar 5.0 wt.% is reached within 60 min and at 100 ∘C and 10 bar 4.0 wt.% is reached within 60 min. The combined effects of Pd and Ni additions prove particularly useful in providing superior kinetics at moderate charging conditions. Hydrogen capacity and kinetics did not deteriorate over at least 50 cycles. These data are compared with those of nanocrystalline MgH2 powders, obtained by intensive milling in argon atmosphere.