Effect of Reactive Ball Milling Time on the Hydrogenation/Dehydrogenation Properties of Nanocomposite MgH2/7TiMn1.5 Powders

摘要

Nanocrystalline MgH2 powders were prepared by high- energy reactive ball milling of pure Mg powders under 50 bar of a hydrogen gas atmosphere. The powders obtained after 200 h of milling were doped with 7 wt% of Mn3.6Ti2.4 powders and then ball milled 50 h, using a high energy ball mill. The as-milled MgH2/7Mn3.6Ti2.4 nanocomposite powders obtained after 200 h of milling were homogeneous in shape (spherical-like), particle size (～ 1.5 μm in diameter) with grain size of less than 10 nm in diameter. (1.5 mm). This nanocomposite binary system enjoyed superior hydrogenation/dehydrogenation kinetics at 275°C, as elucidated by the short time required to absorb and desorb 5.3 wt% H2 within 2 and 8 min, respectively. At this temperature the system possessed excellent absorption/desorption cyclability of 1000 complete cycles within 1400 h.