CN-122000190-A - Reinforcing PbMo6S8Method for grain connectivity of base superconducting wire

Abstract

The invention discloses a method for enhancing connectivity of PbMo 6 S 8 -based superconducting wire grains, which comprises the steps of firstly mixing Pb, mo and S powder uniformly, performing heat treatment to obtain mixed powder of Pb, mo and MoS 2 , secondly grinding part of the mixed powder, sintering to obtain PbMo 6 S 8 powder, thirdly mixing PbMo 6 S 8 powder with the rest of the mixed powder uniformly, pressing into powder rods, fourthly loading the powder rods into an alloy tube, drawing the alloy tube into wires, and fifthly performing heat treatment. According to the invention, on the basis of obtaining high-performance PbMo 6 S 8 superconducting powder, mixed powder of Pb, mo and MoS 2 is added for tubing, so that Pb, mo and MoS 2 react to form PbMo 6 S 8 in situ during heat treatment, original PbMo 6 S 8 superconducting powder crystal grains are connected, the connectivity of the crystal grains is enhanced, the density of core wires is improved, the current carrying performance of the PbMo 6 S 8 -based superconducting wire is improved, and the method is suitable for the field of high-field superconducting magnets.

Inventors

• Shao Baitao
• LIU JIXING
• ZHANG SHENGNAN
• JI LEI
• LI JIANFENG

Assignees

• 西北有色金属研究院

Dates

Publication Date

20260508

Application Date

20260319

Claims (4)

1. 1. A method of enhancing connectivity of grains of PbMo 6 S 8 -based superconducting wire, the method comprising the steps of: Uniformly mixing Pb, mo and S powder according to the atomic ratio of Pb to Mo to S in a target product PbMo 6 S 8 in a glove box protected by argon to obtain mixed powder, and then vacuum sealing the mixed powder in a quartz tube for heat treatment to obtain mixed powder of Pb, mo and MoS 2 ; Step two, fully grinding the mixed powder of part Pb, mo and MoS 2 in the step one in a glove box, and then sealing the ground mixed powder in a quartz tube in vacuum for sintering to obtain PbMo 6 S 8 powder; Uniformly mixing the PbMo 6 S 8 powder obtained in the second step with the mixed powder of Pb, mo and MoS 2 remained in the first step, and pressing into a powder rod; step four, loading the powder rod in the step three into an alloy pipe, and drawing the powder rod into a wire rod; And fifthly, vacuum sealing the wire rod obtained in the step four into a quartz tube for heat treatment to obtain the PbMo 6 S 8 -based superconducting wire rod.
2. 2. The method for enhancing connectivity of grains of PbMo 6 S 8 -based superconducting wire according to claim 1, wherein the mass of the mixed powder of Pb, mo and MoS 2 remaining in the third step is 10% -60% of the mass of the mixed powder of Pb, mo and MoS 2 obtained in the first step.
3. 3. The method for reinforcing grain connectivity of PbMo 6 S 8 -based superconducting wires according to claim 1, wherein in the fourth step, a powder rod is packed into an alloy tube by means of a powder press rod packing tube.
4. 4. The method for enhancing connectivity of grains of a PbMo 6 S 8 -based superconducting wire according to claim 1, wherein the temperature of the heat treatment in the fifth step is 800 ℃ to 1200 ℃ and the heat preservation time is 10h to 70h.

Description

Method for enhancing connectivity of PbMo 6S8 -based superconducting wire crystal grains Technical Field The invention belongs to the technical field of superconducting material preparation, and particularly relates to a method for enhancing connectivity of PbMo 6S8 -based superconducting wire grains. Background With the rapid development of superconducting magnet technology, the steady-state magnetic field strength is increasingly higher, which puts new demands on the performances of superconducting materials for magnets in all aspects. At present, the preparation of high-field magnets mainly uses low-temperature superconducting materials NbTi and Nb 3 Sn. However, the intrinsic upper critical field (H c2) is low, 18T and 25T respectively, and it is difficult to satisfy the preparation of high-field magnets with magnetic field strength higher than 30T. While high temperature superconducting materials are currently used mainly in the form of interpolated coils to increase the magnetic field strength of the magnet. Therefore, development of a novel superconducting material for a high-field magnet is of great importance for further development of superconducting magnet technology and progress of practical application of advancing superconducting materials. In the seventies of the last century, chevrel et al discovered for the first time that molybdenum sulfur compounds have superconductivity. In this system, the PbMo 6S8 superconducting material has the highest superconducting transition temperature of 15K. At the same time, its upper critical field is near 60T at 4.2K, which is very advantageous for its application at low temperature Gao Changxia. In addition, the superconducting material also has small anisotropy and low preparation cost, and is beneficial to winding and industrialized production of superconducting magnets. Therefore, pbMo 6S8 -based superconducting materials are expected to be practical superconducting materials for the next generation of strong magnetic fields. In the process of preparing the PbMo 6S8 superconducting wire by a powder tubing in-situ method, high-quality PbMo 6S8 precursor powder is prepared first, and then the wire is prepared by tubing and drawing. The method can improve the content of superconducting phase in the wire rod core wire and reduce the second phase, but the prepared wire rod has poor grain connectivity. If the powder tubing in-situ method is used for preparing the PbMo 6S8 superconducting wire rod, the raw material powder is firstly filled into a metal tube to prepare the wire rod, and finally the wire rod is subjected to heat treatment to form a phase. Although the wire may form in situ the PbMo 6S8 phase during heat treatment, its grain connectivity is good, a large amount of second phase MoS 2 is easily formed during the reaction. The second phase distributed at the grain boundaries not only hinders the transmission of superconducting current, but also deviates the stoichiometry of the PbMo 6S8 system, resulting in a decrease in the superconducting properties thereof. Therefore, how to reduce the second phase and enhance the connectivity of crystal grains while ensuring the high superconducting performance of the wire core wire is a key to improving the current carrying capacity of the PbMo 6S8 superconducting wire. Disclosure of Invention The technical problem to be solved by the invention is to provide a method for enhancing connectivity of PbMo 6S8 -based superconducting wire grains aiming at the defects in the prior art. According to the method, high-performance PbMo 6S8 superconducting powder and mixed powder of Pb, mo and MoS 2 are mixed to form precursor powder, and a tube is filled to prepare the wire, so that Pb, mo and MoS 2 react in situ to form PbMo 6S8 in the heat treatment process, original PbMo 6S8 superconducting powder crystal grains are effectively connected, the connectivity of the crystal grains is enhanced, the current carrying performance of the PbMo 6S8 -based superconducting wire is improved, and the problem of weak connection of PbMo 6S8 phase crystal grains is solved. In order to solve the technical problems, the technical scheme adopted by the invention is that the method for enhancing connectivity of PbMo 6S8 -based superconducting wire grains is characterized by comprising the following steps: Uniformly mixing Pb, mo and S powder according to the atomic ratio of Pb to Mo to S in a target product PbMo 6S8 in a glove box protected by argon to obtain mixed powder, and then vacuum sealing the mixed powder in a quartz tube for heat treatment to obtain mixed powder of Pb, mo and MoS 2; Step two, fully grinding the mixed powder of part Pb, mo and MoS 2 in the step one in a glove box, and then sealing the ground mixed powder in a quartz tube in vacuum for sintering to obtain PbMo 6S8 powder; Uniformly mixing the PbMo 6S8 powder obtained in the second step with the mixed powder of Pb, mo and MoS 2 remained in the first step, and pressing