INFLUENCE OF F-TREATMENT ON HYDRIDING/DEHYDRIDING PROPERTIES OF La_(1.8)Ca_(0.2)Mg_(14) Ni_3 ALLOY

The influence of F-treatment on the hydriding/dehydriding properties of La_(1.8)Ca_(0.2) Mg_(14) Ni_3 was studied. Results reveal that hydrogen absorption properties of the fluorinated alloy is much better than that of the as-cast alloy. Before activation, the fluorinated alloy can absorb hydrogen under room temperature, and can reach 1.92% (mass) in 20 min, while the as-cast alloy can't absorb hydrogen under the same condition. Furthermore, the alloy can absorb hydrogen at a level of 3.88% (mass) under 453 K in 3 min. Results of X-ray diffraction (XRD) indicate that the alloy contains four phases such as La_2Mg_(17)、Mg_2Ni、LaNi_(2.28) and CaMg_2, after fluorination, a new phase MgF_2 formed, which is the reason of the improvement on hydriding kinetic of the alloy. The scanning electron microscopy (SEM) of the samples were employed to analyze surface morphology of the alloys.