Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 42: Functional materials III: Actuators, sensors and functional devices
MM 42.4: Vortrag
Mittwoch, 9. März 2016, 16:45–17:00, H53
Hydrogen-assisted actuation with nanoporous palladium — •Shan Shi1,2, Jürgen Markmann1,2, and Jörg Weissmüller1,2 — 1Institut für Werkstoffforschung, Werkstoffmechanik, Helmholtz-Zentrum Geesthacht, Geesthacht — 2Institut für Werkstoffphysik und -technologie, Technische Universität Hamburg-Harburg, Hamburg
Nanoporous (np) metals made by electrochemical dealloying exhibit a three dimensional metal network with high specific surface area, which couples the entire material behaviour to surface effects and specifically to electrocapillary effects that induce stress in the network. While dealloying has been demonstrated for many transition metals, studies requiring homogeneous and monolithic np samples have remained restricted to nanoporous gold and gold-based alloys. Based on a systematic optimization of master alloy composition, electrolyte, as well as temperature and potential of corrosion we here demonstrate the preparation of mm-size homogeneous monolithic np palladium (Pd) samples. Thermal coarsening allows to adjust the characteristic ligament size between 30 and 300 nm. Pd readily dissolves hydrogen, which results in volume expansion. We explore the influence of electrocapillary coupling at the surface and of hydrogen alloying in the bulk on the effective macroscopic mechanical strain of np-Pd during electrochemical potential cycles. A remarkably large reversible strain amplitude (about 3.4%), fast response time, and good stability of our np-Pd actuator emphasizes the prospects of np-Pd as a novel functional material.