No abstract available

[en] Tailoring active nickel alloy cathodes for hydrogen evolution in a hot concentrated hydroxide solution was attempted by electrodeposition. The carbon addition to Ni-Mo alloys decreased the nanocrystalline grain size and remarkably enhanced the activity for hydrogen evolution, changing the mechanism of hydrogen evolution. The Tafel slope of hydrogen evolution was about 35 mV per decade. This suggested that the rate-determining step is desorption of adsorbed hydrogen atoms by recombination. As was distinct from the binary Ni-Mo alloys, after open circuit immersion, the overpotential, that is, the activity of nanocrystalline Ni-Mo-C alloys for hydrogen evolution was not changed, indicating the sufficient durability in the practical electrolysis

No abstract available

[en] Preparation of anodes for oxygen evolution in seawater electrolysis was carried out. Manganese-molybdenum double oxides, Mn_1-xMo_xO_2+x, prepared by anodic deposition from MnSO₄-Na₂MoO₄ solutions showed the 100% oxygen evolution efficiency at a current density of 1000 A m^-2 in 0.5 M NaCl at 30 deg. C and pH 12, but an increase in solution temperature resulted in dissolution of the oxides as molybdate and permanganate ions. In order to increase the stability of the electrodes at higher temperatures the addition of iron to the manganese-molybdenum oxides was performed by anodic deposition in MnSO₄-Na₂MoO₄-FeNH₄(SO₄)₂ solutions. The electrodes thus prepared showed the 100% oxygen evolution efficiency at 1000 A m^-2 in 0.5 M NaCl at 30-90 deg. C, when proper amounts of molybdenum and iron were contained. The iron addition also enhanced the oxygen evolution efficiency. The electrodes were not composed of oxide mixtures but triple oxides, Mn_1-x-yMo_xFe_yO_2+x-0.5y, consisting of Mn⁴⁺, Mo⁶⁺ and Fe³⁺. The formation of the triple oxides seemed responsible for enhancement of both oxygen evolution efficiency and stability

[en] A brief review is made of the superconductors used for energy storage magnets and cryostable superconductors manufactured in Japan, 200 meters of the large-current conductor with the cross section of 27 mm x 12.8 mm and with the critical current of about 20 KA at 8T have been recently manufactured. The designs and test results of the conductor are described. Finally, a conceptual design of 50 KA conductors for the energy storage coil rated 100 - 1,000 MWH is presented. (author)

[en] After the First International Industrial Symposium on the Super Collider, the following developmental work on NbTi superconducting Rutherford cable for the Superconducting Super Collider (SSC) was done at Furukawa Electric. (1) Improvement in the critical current density of the SSC wire, based on volume production: The manufacturing process enabling us to achieve the critical current density of more than 3,000 A/mm² at 5 T is being established. (2) Development of large keystone angled cable to be used for modified SSC dipole magnets: Critical current degradation due to cabling is nearly proportional to cross-sectional area reduction of strands. A 5-cm bore, 1-m long dipole magnet having no wedge inside the coils was fabricated by using the large keystone angled cable and successfully tested by KEK. (3) Magnetization measurements on the SSC wire samples: The long term magnetization decay imposing a serious problem in the accelerator design is possibly associated with flux creep phenomenon occurring in a proximity-coupled matrix between NbTi filaments. 6 refs., 6 figs., 1 tab

[en] The present invention relates to a high current capacity superconductor having a high current density and high stability suitable as a superconductive coil for a large superconductive magnet. In a composite superconductor (1) having superconductive wires (2) and an electrically and thermally highly conductive stable metal (4) electrically coupled in the longitudinal direction, a high current capacity composite superconductor characterized by having an inorganic compound film (5) on the surface of the stabilizing metal (4)]

[en] The MFTF-B magnet system requires two 12.5T, 36 cm bore, insert coils. These coils are being constructed with a cryostable Nb₃Sn conductor manufactured by Furukawa Electric Co. The conductor consists of a core soldered into a cold-worked copper housing, which provides strength. The Nb₃Sn core is made by a triple extrusion bronze process. A total of 57 lengths, each 295 m long, have been made and tested. We have made extensive tests on this conductor; these tests include critical current, ambient and 4.2 K mechanical property measurements, critical current as a function of tensile strain, and bending tolerance tests. The critical current density was found to be quite anisotropic in this conductor, with J/sub c/(12T) = 650A/mm² for field perpendicular to the conductor wide face, and J/sub c/(12T) = 500A/mm² for field parallel to the conductor wide face. These values of current density are among the highest reported for a production lot of Nb₃Sn conductor

[en] This paper deals with the systematic analyses and considerations on various types of voltage-current characteristics in large-capacity Nb³Sn superconductors--typically of a few thousands amperes and of cross-sectional area of several tens squared milimeters. The fundamental conclusions are summarized for three cases as follows: For the first case in which current-transfer effect is dominant, in order to determine the critical current, deceptive voltage originating from the current-transfer across the matrix metals must be excluded before applying usual definition such as effective resistivity of 10^-₁₃ /OMEGA/For the second case in which cracking or some fracture occurs in the superconductor, conventional definition of critical current can be reasonably applied because other effects are covered with fracture-induced large voltage. For the third case, ordinary one, in which current-transfer and strain effects exist simultaneously, the same procedure as the first one should be applied. The degradation of critical current due to strain effect can be evaluated by this method

[en] An aluminium-stabilized superconductor to be used for a very large, thin solenoid, TOPAZ, at KEK has been developed employing co-extrusion process with NbTi/Cu monolithic composite wire of 1.8 mm x 3.3 mm and high purity (above 99.999%) aluminium. The superconductor has dimensions of 3.6 mm x 18 mm and cross sectional ratio of 20 : 1 : 1 for Al : Cu : NbTi. Dimensional fluctuation, critical current, residual resistance ratio, and, contact resistance and shear strength between the insert and the aluminium metal, have been investigated. Using the above superconductor, some jointing methods have been also evaluated. The TOPAZ Solenoid has been constructed, using the above super-conductor and employing developed jointing methods, and successfully tested