Method for preparing core-reinforced multi-core MgB2 superconducting wires/strips

Abstract

The invention discloses a method for preparing core-reinforced multi-core MgB2 superconducting wires / strips, which comprises the following steps of: 1, preparing primary composite single-core wires; 2, removing oil stains on the surfaces of the primary composite single-core wires; 3, preparing secondary multi-core composite rods through secondary composite assembly; 4, performing drawing to obtain the core-reinforced multi-core MgB2 superconducting wires; and 5, rolling by using a plain-barrel roller to obtain the core-reinforced multi-core MgB2 superconducting strips. By the method, the kilometer-magnitude core-reinforced multi-core MgB2 superconducting wires / strips of which the strength is enhanced obviously and which have different cross section structures can be prepared, the phenomena of nonuniform and asymmetric distribution of superconducting core wires and the like can be avoided, the practical kilometer-magnitude multi-core MgB2 superconducting wires / strips of which the superconducting core wires and obstruction layers, the core wires and the core wires and wrapping sleeves are tightly bonded and the core wires are uniformly distributed can be prepared, and the requirement of practical application in aspects of superconducting magnets, particularly superconducting nuclear magnetic resonance instruments and the like can be met.

Description

technical field [0001] The invention belongs to the technical field of superconducting material processing engineering, and in particular relates to a core reinforced multi-core MgB 2 Method for the preparation of superconducting wires / tapes. Background technique [0002] The superconducting critical transition temperature (T c ) is 39K of MgB 2 Superconducting materials, because of their low cost, large coherence length, and absence of weak grain boundary connections, can be used in the liquid hydrogen temperature range, while traditional low-temperature superconductors cannot work in this temperature range. It is readily available through cryocoolers without the need for expensive liquid helium. Therefore combined refrigeration cost and material cost, MgB 2 The application of superconducting materials in the magnetic field range of 10K~20K and 1T~3T has obvious technical advantages, and it is expected to replace traditional low temperature and oxide high temperature su...

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Problems solved by technology

[0002] The superconducting critical transition temperature (T c ) is 39K of MgB 2 Superconducting materials, because of their low cost, large coherence length, and absence of weak grain boundary connections, can be used in the liquid hydrogen temperature range, while traditional low-temperature superconductors cannot work in this temperature range. Easily accessible through cryocoolers without the need for expensive liquid helium

Preparation of multi-core MgB by in-situ powder-in-tube process 2 The sheath in the wire strip is mainly made of iron-based materials, and the ferromagnetism of the iron-based sheath material itself affects the MgB 2 The electromagnetic stability of the final application of the superconducting wire strip, and because the work hardening speed of the iron-based sheath material is relatively fast, and the initial reaction phase formation temperature of Mg-B in the superconducting core wire is generally around 550 ° C, the iron-based material The recrystallization temperature is higher than this temperature, and intermediate annealing cannot be performed to eliminate the work hardening phenomenon of the sheath material. In MgB 2 Superconducting wire strips, especially multi-core long-wire strips, are prone to disconnection during the preparation process; at the same time, multi-core MgB 2 During the preparation of superconducting wire strips, the stress in the center of the cross-section of the strip is the most concentrated, and the core wire in the center is prone to sausage-like or broken during processing, and the breakpoint gradually expands to the surrounding core wires during the processing, resulting Overall fracture of multi-core superconducting wire strips

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