| Hydrogen storage is a key issue in the application of hydrogen energy.Mgis considered to be one of the most promising solid hydrogen storage materialsbecause of its advantage such as large hydrogen storage capacity, naturalabundance, low cost and so on. However, Mg has the worse absorption anddesorption behaviors at slow rate and high temperature. Rare earth andtransition elements added to the magnesium-based alloys could catalyze theabsorption and desorption kinetics performance of Mg-based Hydrogen StorageMaterials.In this paper, the alloys are prepared from La, Mg and Ni powders (purityabove99.9%) by Reaction Ball-milling under hydrogen atmosphere. XRD,SEM and TG-DSC were used to analyze the morphology and the hydrogenperformance of the different ball milling process and alloy composition. Themain results are as follows:(1) Nanosize Mg-based hydrogen storage composite(MgH2、LaH3、Ni andMg2NiH4) could be directly synthesized by solid-gas reaction ball-milling,which have lower hydrogen desorption temperature.(2)The milling technology has effect on the particle size of La-Mg-Nihydrogen storage material and the particle size has effect on the hydrogendesorption properties.The long the milling time and the greater the millingspeed, the less the particle size is and the better the hydrogen desorptionproperties is. Particles too refinement alloy surface will increase tension andmutual adhesion on the one hand, the other hand will make the alloy powderactivity increased oxidation. Prolonged milling time not only can not promotesynthesis reaction, but also can have a bad influence.(3) In order to effectively improve the hydrogen desorption property ofthe material, the Mg addition amount,the milling intensity and the ball millingtime must to be reasonably mixed, so that the particle size of the materialreaches the optimum value. In the experiment optimum synthesis conditionswere: ball milled40~60h at280rpm milling speed the amount of Mg addition is24wt%~45wt%. |
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