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A series of multicomponent Zr_0.8,Ti_0.2Mn_0.4V_0.6Ni_(1-x)Fe_x (x=0.00, 0.08, 0.15, 0.22 and 0.30) alloys are prepared and their crystal structure and P-C-T curves are examined. The electrochemical properties of these alloys such as activation conditions, discharge capacity, cycling performance are also investigated. Zr_0.8,Ti_0.2Mn_0.4V_0.6Ni_(1-x)Fe_x, (x=0.00, 0.08, 0.15, 0.22 and 0.30) have the C14 Laves phase hexagonal structure. The electrode was activated by the hotcharging treatment. The best activation conditions were the current density 120 ㎃/g and the hot-charging time 12h at 80℃ in the case of the alloy with x=0.00. The discharge capacity increased rapidly until the fourth cycle and then decreased. The discharge capacity increased again from the 13th cycle, arriving at 234 mAh/g at the 50th cycle. The discharge capacity just after activation decreases with the increase in the amount of the substituted Fe but the cycling performance is improved. The discharge capacity after activation of the alloy with x=0.00 is 157 ㎃h/g at the current density 60 ㎃/g. Zr_0.8,Ti_0.2Mn_0.4V_0.6Ni_0.85Fe_0.15 shows a medium quantity of discharge capacities but a good cycling performance. Another series of multicomponent Zr_0.8,Ti_0.2Mn_0.4V_0.6Ni_0.85Fe_0.15 (M=Fe, Co, Cu, Mo and Al) alloys are prepared. They also have the C14 Laves phase hexagonal structure. The alloys with M=Co and Fe have relatively larger hydrogen storage capacities. The discharge capacities just after activation are relatively large in the case of the alloys with M=Al and Cu. They are 212 and 170 ㎃h/g, respectively, at the current density 60 ㎃/g. Of the alloys investigated, the Zr_0.8,Ti_0.2Mn_0.4V_0.6Ni_0.85Fe_0.15 alloy is the best one showing a relatively large discharge capacity and a good cycling performance. This alloy contains more Ni as compared with the other alloys, and the small particles of this alloys are the clusters of very fine particles. The ICP analysis of the electrolyte for these electrodes after 50 charge-discharge cycles shows that the concentrations of V and Zr are relatively high.

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This paper describes a fundamental investigation of the friction welding condition for the pure copper/ pure titanium joining and the effect of friction time, upset pressure on the mechanical and metallurgical properties of the joint. Taguchi method has been adopted for investigating the contribution of welding variables. Under a constant upset pressure, the tensile strength have a little difference with an increase in friction time. At a constant friction time, the tensile strength increased with an increase in the upset pressure. The tensile fracture of Cu to Ti joint occurred at the Cu base material near the interface.

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Solvent extraction experiments with Alamine336 from hydrochloric acid solutions containing cobalt and nickel have been performed to separate both metal ions. Cobalt was preferentially extracted from nickel by Alamine336 due to the difference betwen the complex formation constant of cobalt-chloro and nickel-chloro complex. The extraction percentage of cobalt and nickel were greatly affected by the concentration of chloride ion but were independent of solution pH when the chloride salt of Alamine336 was used as extractant. In the experimental ranges, the separation factor was increased with reaction temperature. The stripping percentage of cobalt decreased with the concentration of HCl in stripping solution.

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The variation of magnetic properties of electrodeposited thin film Co(P) alloys was studied using a different concentration of ammonium chloride in the solution. Using cyclic voltammetry as an electro-analytical technique, change in cathodic polarization behavior was measured. It was speculated that the kinetics of nucleation and electrocrystallization process of Co(P) alloys was modified by the concentration of ammonium chloride. The addition of ammonium chloride seems to suppress the polarization and kinetics of electrocrystallization by charge tranfer leading to a larger grain size and highly preferred orientation. Such microstructural features were confirmed by imaging and electron diffraction method in the TEM.

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In order to elucidate the fundamental aspects of the minerals formation processes during sintering, the Fe_2O_3-CaO-Al_2O_3-SiO_2 system and the effect of MgO on synthesized iron ore sinter were studied by image analysis and X-ray diffraction method. Most existed calcium ferrite was identified to be a solid solution of CaO·2Fe_2O_3 with a small amount of solubility of Al_2O_3 and SiO_2. With an increase of the content of Al_2O_3 in the system, the amount of calcium ferrite was increased. On the other hand, the amount of calcium ferrite was decreased, and the amount of hematite was increased with increasing the content of SiO_2. Crystal structure of calcium ferrite with Al_2O_3 and SiO_2 was changed from monoclinic to triclinic as well as the unit cell volume shrank with fixing Al_2O_3 and increasing SiO_2. With increasing the content of MgO(1∼3 wt%), the amount of magnetite was increased and hematite was decreased but calcium ferrite was not changed.

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