Abstract
Mg with graphite (Mg+5wt.%Gr) and Mg-TiFe_<0.8>Mn_<0.2> alloy with graphite ((Mg-30wt.%TFM)+5wt.%Gr) or stearic acid ((Mg-30wt.%TFM)+5wt.%SA) composites were gotten with ball milling. The TiFe_<0.8>Mn_<0.2> alloy was used as a catalyst for improving hydrogen absorption-desorption properties of Mg, and the graphite and stearic acid were used as process control agents. We conducted Pressure-Composition-Temperature (PCT) measurements, X-ray diffraction (XRD) analyses and differential scanning calorimetries (DSC) for the samples. Mg+5wt.%Gr, (Mg-30wt.%TFM)+5wt.%Gr and (Mg-30wt.%TFM)+5wt.%SA stored hydrogen up to 0.9 wt.%, 3.6 wt.%, and 1.7 wt.%, respectively at 200℃ on PCT measurements. It might be that the added graphite, which was coated on the fresh surfaces of the samples during the milling process, prevented them from oxidizing, and consequently enhanced the catalytic effect of TiFe_<0.8>Mn_<0.2> alloy. MgH_2 was observed in (Mg-30wt.%TFM)+5wt.%Gr and (Mg-30wt.%TFM)+5wt.%SA with XRD analyses. These samples desorbed hydrogen around 305-335℃ in the DSC processes.
