Preparation method of high density MgB2 superconduction wire material

Abstract

This invention relates to a preparation method for high density MgB₂ super-conduction material including: grinding powders of Mg and B to be sealed in a Ta foil to be put in a heating tube to rise the temperature of 650-950 deg. C for 0.5-10 hours to be sintered for the first time to produce to a MgB₂ super-conduction material to be ground to the powder of 2-3mum then to be mixed with powder of Mg and B to be sintered for the second time to get the high density super-conduction material.

Description

technical field [0001] The present invention relates to a kind of MgB 2 Preparation method of superconducting material, especially a kind of high-density MgB 2 Preparation method of superconducting wire. Background technique [0002] In 2001, the intermetallic compound MgB was discovered 2 The result of superconductivity has caused a great sensation in the field of condensed matter physics and materials science. Because many of its unique properties have not been fully recognized and understood by people, it has attracted widespread attention in many disciplines such as materials, physics, and chemistry. MgB 2 The superconducting critical transition temperature of the superconductor is 39K, and its superconducting temperature is second only to oxide superconductors, doped C 60 Solid material superconductor is a simple and stable intermetallic compound superconducting material with the highest superconducting temperature found so far. MgB 2 The structure is a graphite-...

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Problems solved by technology

[0003] However, in MgB 2 In the preparation process of superconducting materials, especially bulk materials, wires and strips, since Mg and B are raw materials with low density, the density of Mg is 1.74g / cm 3 , the density of B is 2.34g / cm 3 , even after pressing to achieve 100% compactness, its volume will shrink to 76% of its original volume during sintering, and the obtained MgB 2 There are a lot of shrinkage cavities in the sample, and the density is far lower than its theoretical value of 2.62g / cm 3 , and the pressing will not reach 100%, so after sintering, generally only 1.1~1.5g / cm 3 The loose structure of the material is the main reason that limits the increase of the critical current density of the material, and the MgB 2 It has great influence on basic research, performance testing and production processing

[0004] It is recorded in the literature that high-density MgB can be prepared by hot isostatic pressing. 2 Block material (Nesterenko V F, Gu Y. Elastic properties of hot-isostatically-pressed magnesium diboride. Appllied physics letters. 2003, 82(23): 4104-4106), but its equipment is complex and can only be used for block material preparation , cannot be used for wire and strip preparation

It is also documented in the literature that MgB can be used directly 2 High-density MgB powder compacted 2 Materials (Frederick N A, Li S, Maple M B, et al. Improved superconducting properties of MgB 2. Physica C, 2001, 363:1-5.), but due to the made MgB 2 There are a large number of microcracks in the material, and the superconducting current carrying capacity is also limited.