The development of MgB₂superconducting wires fabricated with an internal Mg diffusion (IMD) process

Abstract

In this review, we introduce the development of internal Mg diffusion (IMD)-processed MgB2 superconducting wires. First, a brief history of the IMD method (which has been given different names by different groups) is introduced and the mechanism of IMD MgB2 wire is discussed. Second, factors related to Jc and Je including: boron (B) powder and carbon (C) addition, the ‘effective MgB2 density’ (the MgB2 layer excluding pores, unreacted B particles, MgO, and other impurities), grain size, flux pinning, and connectivity, maximum Mg infiltration distance, B layer thickness and wire diameter, along with other factors such as heat treatment conditions, sheath materials, pressure, and chemical addition are discussed. Third, fabrication processes for IMD long wires, IMD multi-filament wires, and a hybrid method combining IMD and PIT processes are introduced. Fourth, other research related to practical applications, such as the mechanical properties, AC loss of IMD MgB2 wires are introduced. Finally, future work, including the enhancement of Jc (especially Jc at 20–30 K) and the superconducting joint of IMD MgB2 wire are discussed.

High transport current superconductivity in powder-in-tube Ba0.6K0.4Fe2As2tapes at 27 T

“…1(a) shows the magnetic field dependence of the transport critical current density Jc at 4.2 K of Ba-122 tapes in this work and the properties of other type of superconducting wires or tapes are also included. [26][27][28][29] The transport Jc at 4.2 K in this work reaches 1.5  10 5 A/cm 2 (Ic = 437 A) at 10 T and 5.5  10 4 A/cm 2 at 27 T, respectively. These Jc values are the highest values not only for the Ba-122 tapes but 6 also for all of the iron-based superconducting wires and tapes ever reported.…”

Superconducting materials: Challenges and opportunities for large-scale applications

“…After the assembly is cold deformed into wires, the Mg melts and diffuses into the surrounding B powder to form the MgB 2 superconducting phase during the final heat treatment. Compared with the commercialized PIT process, the IMD process is easy to obtain high-density MgB 2 phase, thus achieving high transport J c , so it has been the hotspot for the research of MgB 2 wires ( Ye and Kumakura, 2016 ).…”

“…At present, 100-meter-class MgB 2 wires based on IMD method have been achieved in several labs ( Ye and Kumakura, 2016 ; Wang et al, 2016 ), while companies such as Hyper Tech in the USA, Columbus in Italy, Hitachi in Japan, Sam Dong in South Korea, and Western Superconducting Technologies in China have possessed a production capacity of kilometer-level practical MgB 2 wires ( J c = 1-2×10 5 A/cm 2 at 4.2 K and 4 T) based on the PIT method. Among them, the MgB 2 wires produced by Hyper Tech and Columbus have been successfully employed in applications such as MRI, superconducting fault current limiter, and superconducting cables.…”

“…However, due to the weak flux pinning ability, the critical current density of MgB2 drops rapidly with the increase of applied magnetic field, which limits the application of MgB2 in high magnetic field region. Because of its relatively high Tc, low raw material cost, simple chemical Compared with the commercialized PIT process, the IMD process is easy to obtain high-density MgB2 phase, and thus achieving high transport Jc, so it has been the hotspot for the research of MgB2 wires [61].…”

Solventless Synthesis of Core–Shell LiFePO4/Carbon Composite for Lithium-Ion Battery Cathodes by Direct Pyrolysis of Coronene

“…Our group recently developed a novel method for producing uniform nanometer-scale CCs on amorphous boron powder, when we initially attempted to prepare a uniform dispersion for the carbon doping of MgB 2 superconducting wires. , This technique involves the direct pyrolysis of coronene (C 24 H 12 ), a polycyclic aromatic hydrocarbon comprising six peri-fused benzene rings with a high carbon content of 96%. Transmission electron microscopy (TEM) observation revealed that all boron particles were uniformly coated with carbon to a thickness of several nanometers .…”