Joining condition dependency of joint resistance in ultrasonic welding of high-temperature superconducting tapes with indium

Hayasaka, R.; Yuki, K.; Sato, Yutaka; Hashizume, Hidetoshi

doi:10.1088/1742-6596/1559/1/012065

Cited by 8 publications

(2 citation statements)

References 19 publications

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“…To prevent I c degradation caused by the pyramidal tips of the tools, metal plates were inserted between the CC tapes and the horn and anvil. The quality of the joint was also dependent on the initial thickness of the In foil, which obtained a minimum R sj of 36.1 nΩ•cm 2 [41]. These studies demonstrate that UW and HW methods can be a promising approach for the in-line fabrication of longer tapes required for superconducting devices.…”

Section: Introductionmentioning

confidence: 73%

Performance characteristics of REBCO coated conductor joints fabricated by flux-free hybrid welding

Nisay,

Shin

2023

Supercond. Sci. Technol.

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Recently, the joining of rare-earth barium copper oxide (REBCO) coated conductor (CC) tapes using ultrasonic welding (UW) has demonstrated outstanding potential in the in-line fabrication of longer tapes required for superconducting device applications. The UW method can produce CC joints by applying ultrasonic vibration in less than one second, and hybrid welding (HW) has been adopted to improve further the joint resistance (Rj) and electromechanical properties of the UW CC joints. However, conventional methods for preparing the HW and soldered CC joints involve applying solder flux to remove the oxide film, which can cause corrosion to the surface of the CC tapes and affect the joint's lifespan during device operation. Therefore, this study aims to fabricate a robust HW CC joint of pre-solder insertion without solder flux and compare its joint strength and electromechanical properties with the traditional cases with the solder flux. While similar Rj can be obtained from both cases of HW CC joints, the flux-free HW CC joint has slightly higher joint strength and superior adhesive characteristics than those with flux. The difference in fracture mechanisms after lap-shear and T-peel tests between flux-free HW and with flux was extensively discussed. Additionally, the study investigates the correlation between a decrease in Rj with longer joint length in differently stabilized and processed CC tapes for flux-free HW. Overall, this study demonstrated that the flux-free HW method could efficiently produce robust CC joints with a lesser risk of corrosion and enhanced joint characteristics.

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Section: Introductionmentioning

confidence: 73%

Performance characteristics of REBCO coated conductor joints fabricated by flux-free hybrid welding

Nisay,

Shin

2023

Supercond. Sci. Technol.

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“…Several low resistive joining methods such as Sn-Pb soldering [111], mechanical joint (pressure welding) with In foil inserts [112,113], hybrid welding combined with ultrasonic welding and In-Sn solder infiltration [114,115], and ultrasonic welding with In foil inserts [113,116], have been developed for HTS conductors of REBCO CCs and Bi-2223/Ag tapes. A joint resistivity (product of the joint resistance and joint area) of ∼15-50 nΩ cm 2 at 77 K in selffield was achieved.…”

Section: Low Resistive Joint For Hts Conductorsmentioning

confidence: 99%

Review of the temporal stability of the magnetic field for ultra-high field superconducting magnets with a particular focus on superconducting joints between HTS conductors

Takeda¹,

Maeda²,

Ohki³

et al. 2022

Supercond. Sci. Technol.

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Superconducting magnets used in applications such as magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) require significant temporal magnetic field stability, which can be achieved when the MRI and NMR magnets are operated in the persistent current mode (persistent-mode) using superconducting joints. However, the ultra-high field MRI and NMR magnets are sometimes operated in the driven mode. Herein, we present an analysis of the temporal magnetic field drift and fluctuations observed for MRI and NMR magnets operating in the driven mode and an exploration of effective methods for stabilizing the temporal magnetic field fluctuations. In the last decade, substantial improvements have been achieved in superconducting joints between high-temperature superconductors (HTS). These superconducting joints enable the development of persistent-mode ultra-high field magnets using HTS coils. Therefore, we herein review the superconducting joint technology for HTS conductors and describe the results of the persistent-mode operation achieved by a medium-field NMR magnet using an HTS coil. Particularly, the cutting-edge progress achieved concerning HTS superconducting joints, including joining methods, superconducting properties, and future prospects, is highlighted along with the issues that need to be addressed.

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Optimization of heating profile for superconductor joint performance made by resistive joule heating process

Yang,

Chang,

Hong

et al. 2024

Journal of Materials Research and Technology

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Joining condition dependency of joint resistance in ultrasonic welding of high-temperature superconducting tapes with indium

Cited by 8 publications

References 19 publications

Performance characteristics of REBCO coated conductor joints fabricated by flux-free hybrid welding

Performance characteristics of REBCO coated conductor joints fabricated by flux-free hybrid welding

Review of the temporal stability of the magnetic field for ultra-high field superconducting magnets with a particular focus on superconducting joints between HTS conductors

Optimization of heating profile for superconductor joint performance made by resistive joule heating process

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