Batch-processed melt-textured YBCO with improved quality for motor and bearing applications

Abstract

Results on an established batch process preparing melt-textured YBCO of high quality and in large quantities are reported. We used a standard composition Y1.5Ba2Cu3O7−x+1 wt % CeO2 without further doping to fabricate single domain YBCO monoliths in different sizes and shapes (cylindrical, quadratic) as well as rectangular multi-seeded YBCO monoliths. Up to 2–3 kg of melt-textured YBCO blocks were grown, reproducible in one box furnace run. Top seeding by a self-made SmBCO was improved and rationalized. Optimization of an oxygen annealing treatment led to macro-crack free YBCO monoliths. Each YBCO monolith was characterized by integral levitation force and field mapping. In a single domain, a quadratic monolith with a edge length of 38 mm, a maximum induction of 1.44 T at 77 K and a distance of 0.5 mm was frozen. The reproducibility of the batch process is guaranteed. Mean maximum induction from 1.1 to 1.2 T at 77 K per batch was reached. A trapped magnetic field of 2.5 T was achieved between two single domain monoliths in a gap of 1.5 mm at 77 K. Depending on the application, function elements with different sizes, designs and more or less complex geometry are constructed in several working steps by cutting, machining, bonding and passivation. Selected function elements were checked with field mapping at 77 K. The results of our function elements in HTSC reluctance motors with an output power of up to 200 kW using single domain material are shown. We report on a fly wheel system DYNASTORE and a system to levitate people.

Novel seed for batch cold seeding production of GdBaCuO bulks

“…The trapped field also exceeded the recently reported result in 26 mm GdBCO/Ag single grain containing Gd-2411 (Nb) fabricated in air [21]. For batch process normally several researchers use the commercial RE-123/RE-211 powders [22][23][24], which are around 10 times expensive than RE-123/RE-211 made in research organizations where starting from the oxides, first the RE-123/RE-211 compounds are made and then they are ground to powders. This process is called self-making in our texts.…”

Measurement of the magnetic field inside the holes of a drilled bulk high-Tcsuperconductor

“…Bulk RBCO samples are usually made with either a parallelepipedic or a disk geometry [9,10,11,12] and have typical lengths or diameters of 20 − 50 mm and thicknesses of 5 − 10 mm. With such large volumes, new specifically designed magnetic measurements systems have been developed for characterizing the magnetic properties of bulk RBCO.…”

Peritectic melting of thin films, superheating and applications in growth of REBCO superconductors

“…Batch processing has drawn much attention recently as a cost-effective method of REBCO materials with a uniform quality. Conventionally, samples placed in one layer were grown in one batch [120][121][122][123][124][125][126]. It can be imagined that processing samples placed in multi-layers in one batch is an even more commercially favorable way to fabricate REBCO bulk superconductors since the furnace capacity can be more effectively used.…”