Strictly application-oriented REBCO bulk fabrication

Abstract

The ability to produce large-grain REBCO (RE=Y, Rare Earth) bulk superconductors by melt texturing growth has been improved and refined significantly over the last 20 years. Magnetic bearings, transportation systems, and scientific instrumentation are becoming major innovations of HTS bulk materials. Large grain production is dominated by cold top-seeding melt growth (TSMG). For material optimizing we demonstrate strictly application-oriented fabrication close to the final geometry and thus reducing mechanical machining and assembling work. YBCO hollow cylinder design for journal bearings with radial c axes orientation are obtained by radial-seeding geometry (RSMG). YBCO ring tiles up 120 mm show a perfect cylinder geometry with in-wall a, b orientation and radial c axes. We report improved electric and mechanical bulk properties and demonstrate great production effectiveness. For achieving high field permanent magnets up to 10 T we compare YBCO bulk and ring geometry. Top/bottom double seeded melt growth (DSMG) grain samples provide better magnetic flux trapping capability and show more homogenous properties.

Novel chemical recycling process of REBCO materials showcased on TSMG-processed waste

“…20 Secondary grains can grow in the bulk, significantly deteriorating its properties, which is why such bulks are most often discarded. [21][22][23] Another type of defect is large cracks in the volume of the bulk. 24,25 This is a problem mainly for bulks that are larger in diameter since during growth, the bulks are under higher stress due to high shrinkage during heat treatment.…”

Enhancing magnetic levitation and guidance force and weight efficiency of high‐temperature superconducting maglev systems by using sliced bulk YBCO

“…20,21 During the ongoing studies, the multi-seeded-melt-growth (MSMG) technic has been developed in which more than one seed is used on the material to produce larger-sized singlegrain HTSs in different dimensions and geometries. 18,19,22 Different studies have been performed to enhance the superconducting material properties in addition to the size of the bulk REBCO, such as using a cylindrical 23,24 or pyramid-like 25 buffer layer between the seed and the main material. Notwithstanding the numerous number of studies done so far, the most commonly used bulk YBCO in Maglev studies of laboratory scale 14,15,26 or real-scale prototypes 5,27 are the ones fabricated by ATZ GmbH 8,22,[28][29][30] in a rectangular prism shape with three seeds.…”

“…The first solution to overcome this challenge is the top‐seeded‐melt‐growth (TSMG) method, in which a seed is used on the material to be grown with a higher melting temperature than this material 20,21 . During the ongoing studies, the multi‐seeded‐melt‐growth (MSMG) technic has been developed in which more than one seed is used on the material to produce larger‐sized single‐grain HTSs in different dimensions and geometries 18,19,22 . Different studies have been performed to enhance the superconducting material properties in addition to the size of the bulk REBCO, such as using a cylindrical 23,24 or pyramid‐like 25 buffer layer between the seed and the main material.…”

“…Different studies have been performed to enhance the superconducting material properties in addition to the size of the bulk REBCO, such as using a cylindrical 23,24 or pyramid‐like 25 buffer layer between the seed and the main material. Notwithstanding the numerous number of studies done so far, the most commonly used bulk YBCO in Maglev studies of laboratory scale 14,15,26 or real‐scale prototypes 5,27 are the ones fabricated by ATZ GmbH 8,22,28–30 in a rectangular prism shape with three seeds.…”

Direct fabrication of high-quality ring-shaped REBa2Cu3O y bulk magnets by the single-direction melt growth (SDMG) method

“…A few instances of direct growth of ringshaped bulks using the top-seed method have been reported, such as employing a multi-seed approach or placing a buffer disk on a ring-shaped pellet. [12][13][14][15] Nevertheless, achieving a concentric trapped field in the ring-shaped REBCO bulk using the top-seeded method has been a significant challenge. Despite these hurdles, Nakamura et al have developed the world's first compact 200 MHz NMR systems using stacked EuBCO ring-shaped bulks fabricated by the top-seeded method.…”