Magnesium boride super conductive wire and its preparation method

Abstract

The superconductive line material consists of the line core and the enveloping layer. The material of the line core is MgB2 possessing the superconductive properties. The enveloping layer is the metal cladding composed of low-carbon steel, nickel or tantalum. The preparing steps are as follows. According to mol ratio, Mg powder and B powder being mixed and ground is loaded into the metal tube. When the mixed powder is tight, the two ends of the tube are sealed, which is put into the oxygen free copper tube. Rotary swaging, rolling, vacuum annealing the wire obtain the MgB2 superconductive line. The invention possesses the features of good processability, fine crystal grain of MgB2, intensive connection of crystal grain of MgB2 and no phenomenon of rupture.

Description

technical field [0001] A magnesium boride superconducting wire and a preparation method thereof, relating to a MgB with superconducting properties 2 A circular superconducting wire consisting of phases and metal phases and a preparation method thereof. Background technique [0002] MgB 2 It is a newly discovered intermetallic compound superconductor. Its superconducting transition temperature is as high as 39K, which fills the blank of medium temperature superconductors. It is a new type of superconductor with great application potential in the working range of GM refrigerators (10K-30K). Material. Compared with oxide high-temperature superconductor materials, MgB 2 The crystal structure is simpler, the coherence length is large, and there is no weak connection between grain boundaries, which can carry high current density. At the same time, the price of B elements and Mg elements is low, and the preparation cost is lower than that of high-temperature and low-temperature...

AI Technical Summary

Problems solved by technology

The first method is simple in process, but for MgB 2 The purity requirements of the powder are very high, which will increase the preparation cost, and at the same time due to the MgB 2 The hardness is very high, and the wire is easy to break during processing, so it is impossible to prepare MgB with high critical current density with application value 2 long superconducting wire

MgB prepared by the second method 2 In the superconducting wire, MgB is generated through the reaction of Mg and B 2 , so MgB 2 The grain connection is better and can carry higher current density, but due to avoid MgB during processing 2 It cannot be annealed due to the formation of phase, and the wire is easily broken during processing, so it is difficult to process into a long wire with engineering application value

At the same time, although the international 2 Some progress has been made in sample preparation with short wires, but the biggest problem with these wires is the low critical current density

At present, for MgB with practical engineering application value 2 The preparation of long wires has not been reported, which greatly affects the MgB 2 The practical process of superconductor