Method for increasing superconducting critical current density of ex-situ magnesium diboride block through self reaction

A technology of critical current density and magnesium diboride, which is applied in the field of superconductivity, can solve problems such as poor connectivity and limited critical current density, and achieve the effects of simplifying the preparation process, convenient source, and improving connectivity

Active Publication Date: 2016-05-04
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Among them, the first position method can improve the compression coefficient of magnesium diboride

Method used

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  • Method for increasing superconducting critical current density of ex-situ magnesium diboride block through self reaction
  • Method for increasing superconducting critical current density of ex-situ magnesium diboride block through self reaction
  • Method for increasing superconducting critical current density of ex-situ magnesium diboride block through self reaction

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] commercial MgB 2 Powder 20mg, in The mold was kept at a pressure of 3 MPa for 2 minutes, and finally the cylindrical block was put into a high-temperature differential scanning calorimeter for sintering in an argon protective atmosphere. The rate is reduced to 650°C, maintained at this temperature for 1 hour, and finally cooled to room temperature at a rate of 40°C / min. This sample is named b, and the conditions are 900°C, 0min-650°C, 1h. The phase composition of the prepared sample was determined by X-ray diffraction (XRD), such as figure 2 The corresponding samples are shown in . From figure 2 It can be seen that the sample contains a small amount of MgB 4 . The microstructure was then observed by scanning electron microscopy (SEM), image 3 Figure b in middle is the corresponding SEM scanning picture. Finally, grind the sample to 4×2×1mm 3 The cuboid was tested for comprehensive physical properties, and the curve of the critical current density changing w...

Embodiment 2

[0027] commercial MgB 2 Powder 30mg, in The mold was kept at 5 MPa for 2 minutes, and finally the cylindrical block was put into a high-temperature differential scanning calorimeter for sintering in an argon protective atmosphere. The heating rate was 10°C / min. Decrease to 650°C at a rate of 40°C / min, keep at this temperature for 1 hour, and finally cool to room temperature at a rate of 40°C / min. The sample is named c, and the conditions are: 900°C, 10min—650°C, 1h. The phase composition of the prepared sample was determined by X-ray diffraction (XRD), such as figure 2 The corresponding samples are shown in . From figure 2 It can be seen that the sample contains a small amount of MgB 4 . The microstructure was then observed by scanning electron microscopy (SEM), image 3 Figure c in the middle is the corresponding SEM scanning picture. Finally, grind the sample to 4×2×1mm 3 The cuboid was tested for comprehensive physical properties, and the curve of the critical c...

Embodiment 3

[0029] commercial MgB 2 Powder 60mg, in Keep the pressure in the mold at 10MPa for 2 minutes, and finally put the cylindrical block into the tubular sintering furnace for sintering in the argon protective atmosphere. The heating rate is 10°C / min. The rate is reduced to 650°C, kept at this temperature for 1 hour, and finally cooled to room temperature at a rate of 40°C / min. The sample is named d, and the conditions are: 900°C, 20min—650°C, 1h. The phase composition of the prepared sample was determined by X-ray diffraction (XRD), such as figure 2 The corresponding samples are shown in . From figure 2 It can be seen that the sample contains a small amount of MgB 4 . The microstructure was then observed by scanning electron microscopy (SEM), image 3 Figure d in the middle is the corresponding SEM scanning picture. Finally, grind the sample to 4×2×1mm 3 The cuboid was tested for comprehensive physical properties, and the curve of the critical current density changing ...

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Abstract

The invention discloses a method for increasing the superconducting critical current density of an ex-situ magnesium diboride block through a self reaction. The method for increasing the superconducting critical current density of the ex-situ magnesium diboride block through the self reaction includes the steps that according to an ex-situ method and a two-step sintering method, in the high temperature sintering stage, the self reaction inside the superconducting block is intensified, a new crystal boundary is formed and added, and meanwhile a small quantity of MgB4 impurities are generated; in the low temperature stage, MgB2 is mainly formed through the reaction, the content of the MgB4 impurities is decreased, and the small quantity of left MgB4 impurities serve as efficient magnetic flux pinning to increase the critical current density in the high magnetic field. According to the method, technical operation is easy, other substances do not need to be added, the preparing technology is simplified, and sources of raw materials are also convenient. The problem that pinning is difficult to lead with the ex-situ method is solved, and the content and the size of particles of pinning impurities can be controlled by controlling the sintering procedure. As the reaction is used by controlling temperature, the aim that the intercrystalline connectivity is improved through short-time sintering can be effectively achieved.

Description

technical field [0001] The invention relates to a method for increasing the superconducting critical current density of a prepositioned magnesium diboride bulk material through self-reaction; a method combining a prepositional method and a two-step method to prepare MgB with a higher critical current density 2 bulk material, in which MgB produced at high temperature 4 It can be used as magnetic flux pinning to increase the critical current density under high field, and the internal self-reaction of the block improves the connectivity between particles, which is beneficial to the improvement of the superconducting critical current density, and belongs to the field of superconducting technology. Background technique [0002] In January 2001, Professor Akimitsu of Aoyama Gakuin University announced that the intermetallic compound magnesium diboride (MgB 2 ) The resistance suddenly becomes zero when the temperature drops to 39K (-237.14K). This temperature broke the record of ...

Claims

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Application Information

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IPC IPC(8): C04B35/58C04B35/64
CPCC04B35/58057C04B35/64C04B2235/661C04B2235/96
Inventor 马宗青彭俊明刘永长蔡奇陈宁
Owner TIANJIN UNIV
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