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Method for preparing and conducting cold high pressure densifying on Cu wrapped Ba0.6K0.4Fe2As2 superconducting wire

A technology of superconducting wire and densification, which is applied in the field of preparation and modification of superconducting wire, can solve problems such as unfavorable formation of superconducting wire core, complicated and time-consuming process, and existing safety, so as to realize large-scale production and application, improve superconducting wire Conductivity, improve the effect of density

Inactive Publication Date: 2013-02-20
SOUTHEAST UNIV
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Problems solved by technology

(2) Due to the soft texture of the silver sheath and the release of stress during high-temperature sintering, it is not conducive to the formation of dense superconducting wire cores
Very dense wires can be obtained using hot isostatic pressing (HIP) [10], but the process is very complex and only suitable for short samples
(3) Ba 0.6 K 0.4 Fe 2 As 2 The system contains highly oxidizable elements Ba, K and As elements. The existing process puts the raw materials in a sealed quartz tube or a high-melting point metal tube, and sinters them under the protection of high vacuum or inert gas to obtain the precursor powder. The process is complicated and time-consuming.
In addition, due to the very active chemical properties of K, As is a highly toxic element, there are potential safety hazards during high-temperature sintering, and higher requirements are placed on the preparation laboratory or production room

Method used

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  • Method for preparing and conducting cold high pressure densifying on Cu wrapped Ba0.6K0.4Fe2As2 superconducting wire
  • Method for preparing and conducting cold high pressure densifying on Cu wrapped Ba0.6K0.4Fe2As2 superconducting wire
  • Method for preparing and conducting cold high pressure densifying on Cu wrapped Ba0.6K0.4Fe2As2 superconducting wire

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preparation example Construction

[0027] Preparation of Cu-coated Ba provided by the invention 0.6 K 0.4 Fe 2 As 2 A superconducting wire rod and a cold high-pressure densification method, comprising the steps of:

[0028] Step a. the Ba sheet with a purity of 99.5% to 99.9%, the K sheet with a purity of 95% to 99%, the Fe powder and the As powder with a purity of 99.9% to 99.99%, in an atomic ratio of 0.6:0.4:2: 2 Prepare it in the glove box and put it into a stainless steel ball mill tank. Ba flakes, K flakes, Fe powder and As powder are used as raw materials, and the excess of K is 5% to 10%;

[0029] Step b. Grinding the raw materials for 1 to 2 hours to form a mixed powder at a speed of 1425 to 1725 rpm;

[0030] Step c. Put the mixed powder into the Cu tube, and press and seal both ends of the Cu tube;

[0031] Step d. rolling and drawing the Cu tube containing the raw material powder into a wire rod; sintering the obtained wire rod at 750° C. to 850° C. for 24 to 30 hours under the protection of va...

Embodiment 1

[0036] Mix Ba flakes (purity 99.9%), K flakes (purity 99%), Fe powder and As powder purity (purity 99.99%) in a glove box with an atomic ratio of 0.6:0.44:2:2 and put them into stainless steel In a ball mill jar. The atmosphere in the ball mill jar is high-purity Ar gas, which is sealed with a screw cap and an O-ring. Stainless steel balls are used as the ball milling medium, and the mass ratio of stainless steel balls to raw materials is 10:1. The raw material was milled for 2 hours at 1425 revolutions per minute. Put the powder obtained by the ball mill into the Cu tube, and press and seal both ends of the alloy tube. Using a hand-operated wire crimping machine, the Cu tube containing the raw material powder was directly rolled and drawn into a wire rod, and sintered under vacuum protection at 750 °C for 24 hours to obtain Ba 0.6 K 0.4 Fe 2 As 2 superconducting wire.

Embodiment 2

[0038] Mix Ba flakes (purity 99.9%), K flakes (purity 99%), Fe powder and As powder purity (purity 99.99%) in a glove box with an atomic ratio of 0.6:0.44:2:2 and put them into stainless steel In a ball mill jar. The atmosphere in the ball mill jar is high-purity Ar gas, which is sealed with a screw cap and an O-ring. Stainless steel balls are used as the ball milling medium, and the mass ratio of stainless steel balls to raw materials is 10:1. The raw material was milled for 2 hours at 1425 revolutions per minute. Put the powder obtained by the ball mill into the Cu tube, and press and seal both ends of the alloy tube. Using a hand-operated wire crimping machine, the Cu tube containing the raw material powder is directly rolled and drawn into a wire rod, which is placed in a cold and high-pressure densification device, and the pressure is 2 GPa in the vertical direction and 1 GPa in the horizontal direction. The wire obtained after densification was sintered under vacuum p...

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Abstract

The invention discloses a method for preparing and conducting cold high pressure densifying on a Cu wrapped Ba0.6K0.4Fe2As2 superconducting wire. The method is used for improving critical current density of the wire. Based on a traditional powder in tube (PIT) method and a high-energy ball milling powder alloying method, the method adopts a high-energy ball mill to directly prepare simple substance raw materials into superconducting powder, filling mixed powder into a copper tube and rolling the powder into the wire. The rolled wire is sintered in vacuum or under protection of inert gas, or the wire is subjected to cold high pressure densifying processing and then is sintered. The preparation method includes conducting high-energy ball milling on simple substances of Ba, K, Fe and As with the stoichiometric ratio of 0.6: 0.4: 2: 2 to obtain precursor powder, filling the completely mixed powder into the copper tube, and tightly pressing two ends of the copper tube to prepare the wire in pulling and rolling mode. The prepared wire is sintered in vacuum or under protection of inert gas, or the wire is subjected to cold high pressure densifying processing and then is sintered. The critical current density of the Ba0.6K0.4Fe2As2 superconducting wire prepared by the method under a 4.2K self field reaches 1.5*104A / cm<2> to 2.8*104A / cm<2>.

Description

technical field [0001] The invention relates to a method for preparing and modifying a superconducting wire, in particular to a method for preparing a Cu-coated Ba 0.6 K 0.4 Fe 2 As 2 A superconducting wire and a method for increasing its critical current density by cold high-pressure densification. Background technique [0002] In January 2008, Hidekuma Hosono's group at Tokyo Institute of Technology discovered the superconducting transition temperature T c = 26K new iron-based superconductor LaFeAs(O,F)[1], this breakthrough has opened up a new wave of research on high-temperature superconductivity in the scientific community, and since then many new systems of iron-based superconductors have been discovered one after another[2] -5]. The new iron-based superconductor has the value of superconducting mechanism research [6], but also has potential broad application prospects [7]. In many iron-based superconductor systems, Ba 0.6 K 0.4 Fe 2 As 2 Due to its small ani...

Claims

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Application Information

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IPC IPC(8): H01B13/00H01B12/06
CPCY02E40/642Y02E40/60
Inventor 施智祥丁祎
Owner SOUTHEAST UNIV
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