The Study Of The Preparation And Modification Of Mg-al-based Hydrogen Storage Alloys

Mg and Al which included in the Mg-Al based hydrogen storage alloys areabundant and inexpensive elements.By the two-component composition, Mg17Al12alloy having a high amount ofhydrogen storage which has4.4wt%of the theoretical hydrogen storage capacity. Butits lower hydrogen absorption and desorption properties restrict its practical application.This article studies to modify Mg-Al based hydrogen storage alloys by mechanicalalloying and microwave sintering process and the preparation of alloys.This article was prepared Mg17Al12+x%Mg (x=10,20,30,40,50) alloys bymechanical alloying. Preparation process: argon atmosphere, stainless steel tanks,speed600rpm,20:1ball-to-power percentage,12h grinding time, the alloys arebroken in every two hours in an glove box filled with argon to relieve the alloy sticksphenomenon. And using the same preparation process prepared the Mg17Al12+x%Cu(x=1,5,10,15) alloy and the Mg17Al12+x%Ni (x=1,5,10,15) alloy.Mg17Al12+x%Mg (x=10,20,30,40,50) alloys were synthesized by XRD.Though the XRD, we found Mg and Al formed only one compound Mg17Al12. The restalloys contained only Mg and Mg17Al12composition.The Mg17Al12+x%Cu (x=1,5,10,15) alloys and the Mg17Al12+x%Ni (x=1,5,10,15) alloys were analyzed by XRD analysis and p-C-T test device. Two types ofalloys have generated many intermediate phases, Mg17Al12+x%Cu (x=1,5,10,15)alloys mainly generated Mg32Al42Cu7, Al6CuMg4,Al7Cu3Mg6and other phases,Mg17Al12+x%Ni (x=1,5,10,15) alloys generated Al4Ni3, Al3Ni and other phases.These phase consumed reactants, brought lots effects to the hydrogen absorption anddesorption properties. Mg17Al12+x%Cu (x=1,5,10,15) alloy prepared bymechanical alloying, Cu was added in the alloy play a major role in the modified,when adding5%Cu, absorption and desorption of hydrogen has the best performance.Hydrogen storage capacity is3.89wt%, and the hydrogen desorption rate is80.46%,the beginning of hydrogen desorption at a high hydrogen pressure of1.4MPa.Mg17Al12+x%Ni(x=1,5,10,15) alloy prepared by mechanical alloying, Al3Ni wasadded in the alloy play a major role in the modified, when adding5%Ni, absorptionand desorption of hydrogen has the best performance. Hydrogen storage capacity is3.14wt%, and the hydrogen desorption rate is96.50%, the beginning of hydrogen desorption at a high hydrogen pressure of1.5MPa.Using microwave sintering prepared Mg17Al12alloy under different conditions,the hydrogen absorption and desorption properties of the test results showed thatmicrowave sintering furnace power is4kw, sintering time is30min, the alloy canobtain the best performance, in90min hydrogen absorption capacity reached3.83wt%at350℃, the hydrogen desorption rate was76.50%.Mg17Al12+5%Ni alloy and Mg17Al12+10%Ni alloy prepared by microwavesintering process analyzed by XRD and p-C-T test devices. Though the results,Hydrogen absorption and desorption properties of the alloy decreased compared withthe alloy prepared by mechanical alloying components. As Ni can absorb microwave,increasing the effective absorbing amount of the sample, thus caused excessivesintering phenomenon, and resulting in decreased performance of the alloy.