Morphological change and hydorogen absorption-desorption characterristics of hydorogen-absorbing alloy by meehanical alloying

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10 kinds of alloys for Ni-MH secondary battery were designed by using the relationship between enthalpy for hydride formation and atomic radius, Designed Abs system and AB_2 system alloys were produced by using high frequency fusion fumace, and these conducted the heat treatment afterwards. 3 kinds of alloys (AB_5 and AB_2 : C15, C14) were crushed under 200 meshes by a mortar, and these samples did the mechanical grinding by using ball mill. Change of crystal structure and absorption-desorption characteristics were examined on these alloy powders In addition, an alloy was also produced from metal powders of alloy constituent element by the ball mill.(1)Characteristics of cast alloys Most of produced alloys had electrochemical characteristics along the design. This fact has proven that the reliability of our ally-design method is high (2)Ejection method of crushed alloy powder from ball mill container Alloy powder sample receives the oxidation, when the cover of the ball mill container … More is opened in the air. In order to prevent this oxidation, the sample was taken out after some organic solvents were injected to the ball mill container, Electrochemical characteristics of the sample which injected ethanol were the best. (3)Effect of mechanical grinding(MG) for alloy powders The alloys used in this study were MmNi_<41> Co_<0.4> Mn_<0.2> Al_<0.3_ Fe_<0.1>(AB_5-system), Zr_<0.95> Ti_<0.05>(V_<0.10> Ni_<0.57> Mn_<0.28> Cr_<0.05>) 2.1 (AB_2, C15 type) and Zr_<0.65> Ti_<0.35> (V_<0.10> Ni_<0.57> Mn_<0.28> Co_<0.05>) 1.82(AB_2, C14-type), and MG processing was carried out for 5-200(or 425) hour. These alloy powder became amorphous state with the increase in processing time and the crystallite size became several nano-meter in the end of processing. The maximum hydrogen content in the P-C-T curve decreased with the increase in MG processing time and the equilibrium hydrogen pressure (near the center of the plateau) tended to increase with the increase in MG processing time. On the other hand, electrochemical capacities decreased with the increase in MG processing time. (4)Mechanical alloying of alloy powder with 10% nickel powder Discharge capacity of the alloy including the 10% nickel powder slightly increased further than the alloy without Ni powder Less