Sumitomo Electric Industries, Ltd. (SEI) has developed and commercialized a Bi-2223 high-temperature superconducting wire and named it “Drastically Innovative BSCCO (DI-BSCCO^®). After the over-pressure sintering method and the pre-tensioned lamination technique were introduced, critical current and mechanical properties of Ag-sheath Bi-2223 wire have been drastically improved, though further enhancement of their properties is necessary for promoting practical applications such as current lead, cable, magnet and motor applications. For the high field magnet application, reinforced wire partially applied for 25T magnet, which is available as magnet opening to the public at the Institute for Materials Research, Tohoku University. For the high field NMR, MIRAI project is underway to develop a magnet of 1.3 GHz (30.5 T) and reinforced wire partially applied for the magnet. For the current lead application, our low thermal conducting wires have been widely used for liquid helium cooling magnets and implemented the clinical MRI machine magnets. In the International Thermonuclear Experimental Reactor (ITER) project, current lead with current capacity of 68kA using our low thermal conducting wire was developed by the Institute of Plasma Physics, Chinese Academy of Sciences.
We have developed a high-strength wire with critical tensile stress of 500MPa at 77K. The Ni reinforced wire was realized by increasing the thickness of the Ni reinforcing tape to 100 µm with the pre-tensioned lamination technique. Furthermore, in order to solve the problem of high splice resistance of wire that use Ni alloys, we developed a method of peeling off the reinforcement tape of the wire. By splicing with this method, we succeeded in reducing the splice resistance of 77K by 75% compared to the normal connection method.
In the presentation, the recent progress of Ag-sheath Bi-2223 wire will present.