Variations of the Hydriding and Dehydriding Rates of As-Milled MgH2-Ni Alloys with Ni Content

In this work, MgH2 was used as a starting material. Samples with compositions of 94 wt% MgH2- 6 wt% Ni, 88 wt% MgH2-12 wt% Ni, 85 wt% MgH2-15 wt% Ni, and 82 wt% MgH2-18 wt% Ni were prepared by reactive mechanical grinding. The variations of the hydriding and dehydriding properties at the first hydriding-dehydriding cycle with Ni content were then investigated. MgH2-12Ni had the highest hydriding rate and the largest quantity of hydrogen absorbed for 60 min, followed in order by MgH2-6Ni, MgH2-15Ni, and MgH2-18Ni. The effects of reactive mechanical grinding were the strongest in the MgH2-12Ni sample. As the Ni content increased from 6 wt% to 18 wt%, the percentage of the hydrogen quantity desorbed for 30 min to the theoretical capacity increased. (Received October 5, 2012)