BATCH-PROCESSING AND BONDING OF MELT-TEXTURED YBCO FOR MOTOR APPLICATIONS

A batch consisting of 30 cylindrical YBCO blocks can be prepared in on e box furnace run. We add Y2O3 to the 123 powder (Solvay) for a standa rd composition of Y1.5Ba2Cu3O7-x. Seeding by single crystalline MgO pr oduces a single domain material. The quality of these blocks with a di amater of 30 mm and a height of 18 mm is tested by non-destructive lev itation force measurements or field mapping. Zero field cooled levitat ion forces higher than 60 N were achieved. This value corresponds to a pproximate to 80% of the theoretical limit of the permanent magnet use d. In single domain material a maximum induction of 883 mT is frozen a t 77 K. For HTSC hysteresis motors, where the rotor consists of melt-t extured YBCO, more complex geometries are necessary. By cutting and ma chining the cylindrical blocks, structures can be constructed consisti ng of several monoliths, e.g. in a 'cloverleaf' configuration. A bondi ng technique was developed to assemble the tiles. The adhesive strengt h allows accelleration of the rotor up to speeds greater than 3000 rpm . A maximum output power of 1 kW has been achieved. The development of a 10 kW motor is in progress. (C) 1998 Elsevier Science S.A. All righ ts reserved.