Batch-processing and bonding of melt-textured YBCO for motor applications

A batch consisting of 30 cylindrical YBCO blocks can be prepared in one box furnace run. We add Y2O3 to the 123 powder (Solvay) for a standard composition of Y1.5Ba2Cu3O7-x. Seeding by single crystalline MgO produces a single domain material. The quality of these blocks with a diamater of 30 mm and a height of 18 mm is tested by non-destructive levitation force measurements or field mapping. Zero field cooled levitation forces higher than 60 N were achieved. This value corresponds to ≈ 80% of the theoretical limit of the permanent magnet used. In single domain material a maximum induction of 883 mT is frozen at 77 K. For HTSC hysteresis motors, where the rotor consists of melt-textured YBCO, more complex geometries are necessary. By cutting and machining the cylindrical blocks, structures can be constructed consisting of several monoliths, e.g. in a ‘cloverleaf’ configuration. A bonding technique was developed to assemble the tiles. The adhesive strength allows acceleration 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.