Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 3: Adsorption I
O 3.6: Vortrag
Montag, 27. März 2006, 12:30–12:45, TRE Phys
Investigations on segregation in modern hydrogen storage alloys — •Mark Schülke1, Janos Giber2, Gabor Kiss2, Martin Lammers3, Karl-Heinz Müller1,3, and Hubert Paulus3 — 1University of Applied Sciences of South Westphalia, Luebecker Ring 2, 59494 Soest, Germany — 2Technical University of Budapest, Institute of physics, Chair of atom physics, H-1111 Budapest, Budafoki ut 8, Hungary — 3Institute for Technology and Knowledge Transfer (TWS), Luebecker Ring 2, 59494 Soest, Germany
Before the first use hydrogen storage alloys have to be activated by means of several heating cycles combined with hydrogen flushing. According to former publications, the key mechanism to the understanding of the activation process is surface segregation induced by selective oxidation. [1] But it is also known from previous experiments with model systems that the thermodynamic segregation of alloy components and of oxygen solved in the bulk influences the hydrogen absorption as well.
Samples of the AB2 Laves phase alloy Ti0.95Zr0.05Mn1.53V0.47Fe0.08Al0.02 with an oxygen content of ca. 0.9 at% (from manufacturing) were tempered for different periods of time (30 s, 1 min, 1 h, 5 h) at 100 ∘C and 200 ∘C and analyzed by means of different surface analysis methods (SNMS, XPS, AES, depth profiles) afterwards. In addition to oxygen, Mn and Fe are enriched in a surface layer with a thickness of about 20 nm.
In future investigations the influence of defined surface conditions on the hydrogen absorption shall be examined.
[1] L. Schlapbach in: Hydrogen in Intermetallic Compounds II, Topics in Applied Physics, vol. 67, ed. L. Schlapbach, Springer, 1992.