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  • Microstructure and kinetics...
    Mirabile Gattia, D.; Di Girolamo, G.; Montone, A.

    Journal of alloys and compounds, 12/2014, Letnik: 615
    Journal Article, Conference Proceeding

    •MgH2 was ball milled with TiO2 anatase phase and expanded graphite to prepare pellets.•Different pellets have been prepared at different compression load.•Pellets were repeatedly cycled under hydrogen pressure to simulate tank exercise and verify their stability.•The compression load highly affects the stability of the pellets to cycling.•Microstructural evolution of the particles due to cycling have been observed. The interest in Mg-based hydrides for solid state hydrogen storage is associated to their capability to reversibly absorb and desorb large amounts of hydrogen. In this work MgH2 powder with 5wt.% TiO2 was ball milled for 10h. The as-milled nanostructured powder was enriched with 5wt.% of Expanded Natural Graphite (ENG) and then compacted in cylindrical pellets by cold pressing using different loads. Both the powder and the pellets were subjected to kinetic and thermodynamic tests using a Sievert’s type gas reaction controller, in order to study the microstructural and kinetic changes which took place during repeated H2 absorption and desorption cycles. The pellets exhibited good kinetic performance and durability, even if the pressure of compaction revealed to be an important parameter for their mechanical stability. Scanning Electron Microscopy observations of as-prepared and cycled pellets were carried out to investigate the evolution of their microstructure. In turn the phase composition before and after cycling was analyzed by X-ray diffraction.