CN108163867A - The method for preparing magnesium diboride superconductive bulk by magnesium diffusion method using graphene in-stiu coating boron powder - Google Patents

The method for preparing magnesium diboride superconductive bulk by magnesium diffusion method using graphene in-stiu coating boron powder Download PDF

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CN108163867A
CN108163867A CN201810086327.3A CN201810086327A CN108163867A CN 108163867 A CN108163867 A CN 108163867A CN 201810086327 A CN201810086327 A CN 201810086327A CN 108163867 A CN108163867 A CN 108163867A
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graphene
boron powder
magnesium
prepared
graphene oxide
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李文献
康吉祥
付思玮
何小芳
于上家
胡业旻
朱明原
李瑛�
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University of Shanghai for Science and Technology
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    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B35/00—Boron; Compounds thereof
    • C01B35/02—Boron; Borides
    • C01B35/04—Metal borides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B12/00—Superconductive or hyperconductive conductors, cables, or transmission lines
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/82—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by IR- or Raman-data
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

Abstract

The invention discloses a kind of methods for preparing magnesium diboride superconductive bulk by magnesium diffusion method using graphene in-stiu coating boron powder, and graphene oxide water solution, boron powder and deionized water are uniformly mixed, obtain boron powder and graphene oxide mixed solution；Boron powder and graphene oxide mixed solution are placed in hydrothermal reaction kettle again, by hydro-thermal reaction make graphene oxide be reduced to graphene and with boron powder it is compound, precipitation is taken to be dried in vacuo after product is centrifuged, obtains graphene in-stiu coating boron powder；Required shape presoma block is made in graphene in-stiu coating boron powder again；It will be fitted into after being sealed in iron pipe and be heat-treated together with presoma block and magnesium powder again, obtain blocky mgb 2 superconductor.It is compound to stablizing for boron powder that the present invention by controllable graphene combination process realizes graphene, uniformly cladding, it avoids the contraction and reunion of graphene in conventional method, then prepares by magnesium diffusion method that crystal boundary connectivity is good, has the compactness magnesium boride bulks of a large amount of graphene pinning center.

Description

Magnesium diboride superconductive block is prepared by magnesium diffusion method using graphene in-stiu coating boron powder The method of material
Technical field
The present invention relates to a kind of preparation methods of magnesium diboride superconductive bulk, are mixed more particularly to the second phase carbon of one kind The preparation method of miscellaneous magnesium diboride superconductive bulk, applied to superconductor preparing technical field.
Background technology
MgB2Critical transition temperature with 39K, simple in structure, coherence length is big, in addition, high-temperature superconductor is not present in it Weak link effect, and also have higher self-fields critical current density.Due to above-mentioned advantage, MgB2Have become commercial low The excellent substitute of temperature superconductive material, such as NbTi.However, due to MgB2Flux pinning ability it is bad, upper critical field and not Reversible field is relatively low, and critical current density decays rapidly under highfield, limits MgB2Extensive use.
In order to improve MgB2Flux pinning ability, we can by irradiate or adulterate introduce pinning center, effectively carry High irreversible field and critical current density.The achievement obtained in past research with carbon and carbon compound doping is preferable, a side There is provided atom replacements in face, cause distortion of lattice, increase electron scattering so as to improve upper critical field, on the other hand then draw Second Phase Particle is entered as pinning center.But it is poor by the second phase dispersibility that Traditional dopant mode introduces, easily reunite Cause the reduction of crystal boundary connectivity, pinning center generally point pinning or the body pinning of formation are close for pining force and critical current The promotion of degree is limited.
Currently used MgB2Technology of preparing is usually solid reaction process in situ, high temperature solid-state after magnesium powder is mixed with boron powder Reaction generation MgB2Block or wire rod, band.Chinese patent such as Publication No. CN105931750 discloses a kind of " graphene The method that Boron Coated powder prepares MgB 2 superconductor wire material ", what is used in disclosed method is solid phase reaction process life in situ Produce MgB2Wire rod, and can not stablize during its graphene coated boron powder, definitely control graphene doping ratio；It is for another example public The number of opening is that the Chinese patent of CN106205861 discloses a kind of " system of graphene-supported multi-element doping magnesium diboride superconductive bulk Preparation Method " equally prepares MgB using in-situ method2, due to volume contraction huge in magnesium, boron reaction process, made from in-situ method MgB2A large amount of hole is usually contained in matrix, causes crystal boundary connectivity poor, effective critical current density is relatively low.
Invention content
In order to solve prior art problem, it is an object of the present invention to overcome the deficiencies of the prior art, and to provide one kind The method for preparing magnesium diboride superconductive bulk by magnesium diffusion method using graphene in-stiu coating boron powder, by by boron powder and oxidation Graphene uniform is scattered in aqueous solution, graphene oxide is enabled to be reduced to graphene by hydro-thermal reaction, avoids the receipts of graphene Uniform cladding of the graphene to boron powder is realized in contracting and reunion；Meanwhile the graphene in-stiu coating prepared using present invention process Boron powder is stably controlled graphene doping ratio.Then, presoma block, then profit is made in the boron powder of foregoing graphites alkene in-stiu coating Fine and close MgB is made with magnesium diffusion method2Bulk wherein a large amount of graphenes connect crystal grain, improves crystal boundary connectivity, in addition graphite Alkene hinders MgB2Grain growth, crystal grain thinning increase a large amount of pinning center, effectively increase so as to provide additional crystal boundary The flux pinning force and critical current density of material.
In order to achieve the above objectives, the present invention adopts the following technical scheme that：
A kind of method for preparing magnesium diboride superconductive bulk by magnesium diffusion method using graphene in-stiu coating boron powder, including Following steps：
(1) graphene oxide water solution is prepared；
(2) graphene oxide water solution, boron powder and the deionized water that are prepared in the step (1) are uniformly mixed It closes, obtains boron powder and graphene oxide mixed solution；
(3) the boron powder prepared in the step (2) is placed in hydrothermal reaction kettle with graphene oxide mixed solution, passed through Hydro-thermal reaction makes graphene oxide by thermal decomposition and reduction be graphene, and make the progress of reduzate graphene and boron powder compound, then Combination product is centrifuged, then precipitation is taken to be dried in vacuo, obtains graphene in-stiu coating boron powder；
(4) the graphene in-stiu coating boron powder prepared in the step (3) is made to the presoma block of required shape；
(5) it is 2 according to the atomic ratio of boron and magnesium:1 ratio, by the presoma block prepared in the step (4) with Magnesium powder is fitted into iron pipe, and iron pipe both ends are sealed, and obtains presoma block and the tubulature complex of boron powder mixing, then Using diffusion method, tubulature complex is placed in diffusion heat treatments stove, to presoma block and boron under non-oxide protective atmosphere Powder mixture is heat-treated, and obtains blocky mgb 2 superconductor.The non-oxide protective atmosphere for being diffused heat treatment is preferred Using inert protective gas atmosphere, restitutive protection's gas atmosphere or vacuum state environment.
As currently preferred technical solution, two boronations are prepared by magnesium diffusion method using graphene in-stiu coating boron powder The method of magnesium superconduction block material, includes the following steps：
(1) graphene oxide water solution is prepared；
(2) graphene oxide water solution, boron powder and the deionized water that are prepared in the step (1) are uniformly mixed Close, obtain boron powder and graphene oxide mixed solution, wherein the graphene oxide quality be boron silty amount 0.01~ 20wt.%；Graphene oxide water solution, boron powder and deionized water carry out mixed uniformly mode preferably using ultrasonic agitation and machine The mixing mode of any one or the two in tool stirring；Graphene oxide water solution, boron powder and deionized water carry out Mixed uniformly mode using ultrasonic agitation and churned mechanically mixing mode, preferably last for mixing time for 6~for 24 hours, The ultrasonic power preferably used is wherein stirred by ultrasonic as 200~1000W；As currently preferred technical solution, aoxidized When graphene aqueous solution, boron powder and deionized water are uniformly mixed, boron powder is taken to add in deionized water first, is stirred using ultrasound Mixing machinery stirring, which is carried out at the same time, to be disperseed, then lasting to be mixed, and obtains boron powder dispersion liquid；It measures in the step (1) graphene oxide water solution prepared in is slowly dropped into after being diluted dropwise in the boron powder dispersion liquid for keeping being mixed, Until graphene oxide water solution is added dropwise, then keep ultrasonic agitation at least 5min；Then stop ultrasonic agitation, obtain boron powder With graphene oxide mixed solution；It is preferred that control graphene oxide quality is 3~10wt.% of boron silty amount；
(3) the boron powder prepared in the step (2) and graphene oxide mixed solution are placed in hydrothermal reaction kettle, control Hydrothermal temperature is 50~250 DEG C, and the hydro-thermal reaction duration is 5min~50h, makes graphene oxide by hydro-thermal reaction It is graphene by thermal decomposition and reduction, and it is compound that reduzate graphene is made to be carried out with boron powder, then combination product is centrifuged, so After precipitation is taken to be dried in vacuo, obtain graphene in-stiu coating boron powder；It is preferred that control hydrothermal temperature is 120~180 DEG C, The hydro-thermal reaction duration is 6~48h；
(4) the graphene in-stiu coating boron powder prepared in the step (3) is made to the presoma block of sheet；It is preferred that Using pressure forming method, the presoma block of sheet is prepared, it is 8.5~12MPa preferably to control pressing process pressure, lasting to protect Press 1~5min of time；
(5) it is 2 according to the atomic ratio of boron and magnesium:1 ratio, by the presoma block prepared in the step (4) with Magnesium powder is fitted into iron pipe, and iron pipe both ends are sealed, and obtains presoma block and the tubulature complex of boron powder mixing, then Using diffusion method, tubulature complex is placed in diffusion heat treatments stove, to presoma block and boron under non-oxide protective atmosphere Powder mixture is heat-treated, and the thermal system for controlling diffusion heat treatments is that heat treatment temperature is 500~1200 DEG C, and heat treatment rises Warm speed is 1~100 DEG C/min, heat treatment soaking time for 0.5~for 24 hours, finally using cooling rate as 1~100 DEG C/min with Stove is cooled to room temperature, and obtains blocky mgb 2 superconductor.It is preferred that the thermal system of control diffusion heat treatments is that heat treatment temperature is 650~900 DEG C, heat treatment heating rate is 5~10 DEG C/min, and heat treatment soaking time is 1~10h, finally with cooling rate Room temperature is cooled to the furnace for 5~10 DEG C/min, obtains blocky mgb 2 superconductor.
The present invention compared with prior art, has following obvious prominent substantive distinguishing features and remarkable advantage：
1. the method for the present invention utilizes graphene oxide good dispersibility in aqueous solution, boron powder and graphene oxide are realized Uniformly mixing, then the boron powder that graphene uniform coats is obtained by hydro-thermal reaction, avoid in conventional method graphene shrink and The phenomenon that reunion；
2. the method for the present invention utilizes hydro-thermal reaction redox graphene, doping is stably and controllable, to explore optimal doping Condition and technique are provided convenience；
3. the method for the present invention prepares magnesium diboride superconductive bulk by diffusion method, porosity is reduced, improves crystal boundary connectivity, Increase critical current density；
4. the method for the present invention prepares magnesium diboride superconductive block using graphene in-stiu coating boron powder, crystal boundary connection is improved Property, graphene also counteracts MgB as effective pinning center2Grain growth, crystal grain thinning is so as to provide additional crystalline substance Boundary increases a large amount of pinning center, effectively increases the flux pinning force and critical current density of material.
Description of the drawings
Fig. 1 is the scanning electron microscope diagram piece of graphene in-stiu coating boron powder material prepared by the embodiment of the present invention one.
Fig. 2 is the X ray diffracting spectrum of graphene in-stiu coating boron powder material prepared by the embodiment of the present invention one.
Fig. 3 is the Raman spectrum of graphene in-stiu coating boron powder material prepared by the embodiment of the present invention one.
Fig. 4 is MgB prepared by the embodiment of the present invention one2The X ray diffracting spectrum of bulk.
Specific embodiment
Said program is described further below in conjunction with specific examples of the implementation, the preferred embodiment of the present invention is described in detail such as Under：
Embodiment one：
In the present embodiment, it is a kind of to prepare two by magnesium diffusion method using graphene in-stiu coating boron powder referring to Fig. 1~4 The method of boronation magnesium superconduction block material, includes the following steps：
(1) graphene oxide water solution is prepared by improved Hummers methods；
(2) graphene oxide water solution, boron powder and the deionized water that are prepared in the step (1) are uniformly mixed It closes, obtains boron powder and graphene oxide mixed solution, wherein the graphene oxide quality is the 3wt.% of boron silty amount；It carries out When graphene oxide water solution, boron powder and deionized water are uniformly mixed, boron powder is taken to add in deionized water first, using super Sound stirs and mechanical agitation replaces 2 times into its dispersion is about to, then lasting to be mixed, and obtains boron powder dispersion liquid；It measures certain The graphene oxide water solution prepared in the step (1) of amount is slowly dropped into holding and is mixed dropwise after being diluted Boron powder dispersion liquid in, often be added dropwise 1mL then switch to be stirred by ultrasonic, mechanical agitation be added dropwise with ultrasonic agitation dispersion alternately, directly It is added dropwise to graphene oxide water solution, then continuing vigorous stirs to get boron powder and graphene oxide mixed solution；Wherein The ultrasonic power preferably used is stirred by ultrasonic as 450W, it is 6h to continue mixing time；
(3) the boron powder prepared in the step (2) and graphene oxide mixed solution are placed in hydrothermal reaction kettle, control Hydrothermal temperature is 180 DEG C, and the hydro-thermal reaction duration is 30h, graphene oxide is made to be gone back by thermal decomposition by hydro-thermal reaction Originally be graphene, and it is compound to carry out reduzate graphene and boron powder, then combination product is centrifuged, then take precipitate into Row vacuum drying, obtains graphene in-stiu coating boron powder；
(4) with pressure forming method, the graphene in-stiu coating boron powder prepared in the step (3) is placed in mold In, presoma disk is pressed into hydraulic press, control pressing process pressure is 8.5MPa, continues dwell time 1min；
(5) it is 2 according to the atomic ratio of boron and magnesium:1 ratio, by the presoma block prepared in the step (4) with Magnesium powder is fitted into iron pipe, and iron pipe both ends are sealed, and obtains presoma block and the tubulature complex of boron powder mixing, then Using diffusion method, tubulature complex is placed in tubular type diffusion heat treatments stove, to preceding under the argon atmosphere of lasting circulation It drives body block and boron powder mixture is heat-treated, the thermal system for controlling diffusion heat treatments is that heat treatment temperature is 850 DEG C, heat Processing heating rate is 5 DEG C/min, and heat treatment soaking time is 10h, finally cools to room with the furnace by 5 DEG C/min of cooling rate Temperature obtains blocky mgb 2 superconductor.
The present embodiment experimental test and analysis：
Intermediate materials manufactured in the present embodiment and the magnesium diboride superconductive block finally prepared are detected respectively, are used The phase composition of X-ray diffractometer (XRD) analysis of material, using the pattern of scanning electron microscope observation material surface, using drawing Graceful spectrometer analysis material character.Referring to Fig. 1~4.Fig. 1 is sweeping for graphene in-stiu coating boron powder material manufactured in the present embodiment Electron microscope picture is retouched, from figure 1 it appears that graphene uniform Boron Coated powder, no stacking and agglomeration, are presented thin slice State.Fig. 2 is the X ray diffracting spectrum of graphene in-stiu coating boron powder material manufactured in the present embodiment, as can be seen from Figure 2 The diffraction maximum unobvious of graphene oxide after showing that graphene oxide is reduced, form graphene in-stiu coating boron powder material.Figure 3 be the Raman spectrum of graphene in-stiu coating boron powder material manufactured in the present embodiment, from figure 3, it can be seen that graphene sheet layer Number is less, and compound good with boron powder.Fig. 4 is MgB manufactured in the present embodiment2The X ray diffracting spectrum of bulk, can from Fig. 4 To find out, as can be seen from Figure 4 MgB2/ G diffraction maximums have excellent crystallinity.Magnesium diboride bulk manufactured in the present embodiment In 20K, 3T, critical current density reaches 2.35 × 104A/cm2。
It is compound to stablizing for boron powder that the present embodiment by controllable graphene combination process realizes graphene, uniformly wraps It covers, avoids the contraction and reunion of graphene in conventional method, then prepare by magnesium diffusion method that crystal boundary connectivity is good, it is big to have Measure the compactness magnesium boride bulk of graphene pinning center.The present embodiment uses diffusion method, and diffusion method is the magnesium of melting or evaporation It diffuses into boryl body and reacts generation MgB2Technology, since its is simple for process, and MgB can be greatly reduced2Porosity, Crystal boundary connectivity is improved, increases critical current density, is to prepare fine and close MgB2The favorable method of block or wire rod.This implementation exists At a temperature of 850 DEG C of diffusion heat treatments, Mg is made uniformly to be diffused into presoma disk, obtain the magnesium diboride of distributed components Superconducting block makes doped source be evenly distributed, and is not in apparent volume contraction phenomenon, ensure that MgB2Block superconductor it is whole Body performance.
Embodiment two：
The present embodiment and embodiment one are essentially identical, are particular in that：
In the present embodiment, it is a kind of that magnesium diboride superconductive block is prepared by magnesium diffusion method using graphene in-stiu coating boron powder The method of material, includes the following steps：
(1) graphene oxide water solution is prepared by improved Hummers methods；
(2) graphene oxide water solution, boron powder and the deionized water that are prepared in the step (1) are uniformly mixed It closes, obtains boron powder and graphene oxide mixed solution, wherein the graphene oxide quality is the 5wt.% of boron silty amount；It carries out When graphene oxide water solution, boron powder and deionized water are uniformly mixed, boron powder is taken to add in deionized water first, using super Sound stirs and mechanical agitation is carried out at the same time and is disperseed, then lasting to be mixed, and obtains boron powder dispersion liquid；It measures a certain amount of The graphene oxide water solution prepared in the step (1) is slowly dropped into the boron for keeping being mixed dropwise after being diluted In powder dispersion liquid, until graphene oxide water solution is added dropwise, then ultrasonic agitation at least 5min is kept；Then stop ultrasound stirring It mixes, obtains boron powder and graphene oxide mixed solution；The ultrasonic power preferably used is wherein stirred by ultrasonic as 200W, it is lasting to stir Time is 16h；
(3) the boron powder prepared in the step (2) and graphene oxide mixed solution are placed in hydrothermal reaction kettle, control Hydrothermal temperature is 160 DEG C, and the hydro-thermal reaction duration is 48h, graphene oxide is made to be gone back by thermal decomposition by hydro-thermal reaction Originally be graphene, and it is compound to carry out reduzate graphene and boron powder, then combination product is centrifuged, then take precipitate into Row vacuum drying, obtains graphene in-stiu coating boron powder；
(4) with pressure forming method, the graphene in-stiu coating boron powder prepared in the step (3) is placed in mold In, presoma disk is pressed into hydraulic press, control pressing process pressure is 12MPa, continues dwell time 5min；
(5) it is 2 according to the atomic ratio of boron and magnesium:1 ratio, by the presoma block prepared in the step (4) with Magnesium powder is fitted into iron pipe, and iron pipe both ends are sealed, and obtains presoma block and the tubulature complex of boron powder mixing, then Using diffusion method, tubulature complex is placed in tubular type diffusion heat treatments stove, to presoma under hydrogen-argon-mixed protective atmosphere Block and boron powder mixture are heat-treated, and the hydrogen-argon-mixed hydrogen volume content is 5%, control the heat of diffusion heat treatments System is that heat treatment temperature is 900 DEG C, and heat treatment heating rate is 5 DEG C/min, and heat treatment soaking time is 3h, finally with drop Warm speed cools to room temperature with the furnace for 10 DEG C/min, obtains blocky mgb 2 superconductor.
The present embodiment experimental test and analysis：
For magnesium diboride bulk manufactured in the present embodiment in 20K, 3T, critical current density reaches 3.03 × 104A/cm2。
It is compound to stablizing for boron powder that the present embodiment by controllable graphene combination process realizes graphene, uniformly wraps It covers, avoids the contraction and reunion of graphene in conventional method, then prepare by magnesium diffusion method that crystal boundary connectivity is good, it is big to have Measure the compactness magnesium boride bulk of graphene pinning center.The present embodiment uses diffusion method, and diffusion method is the magnesium of melting or evaporation It diffuses into boryl body and reacts generation MgB2Technology, since its is simple for process, and MgB can be greatly reduced2Porosity, Crystal boundary connectivity is improved, increases critical current density, is to prepare fine and close MgB2The favorable method of block or wire rod.This implementation exists At a temperature of 900 DEG C of diffusion heat treatments, Mg is made uniformly to be diffused into presoma disk, obtain the magnesium diboride of distributed components Superconducting block makes doped source be evenly distributed, and is not in apparent volume contraction phenomenon, ensure that MgB2Block superconductor it is whole Body performance.
Embodiment three：
The present embodiment is substantially the same as in the previous example, and is particular in that：
In the present embodiment, it is a kind of that magnesium diboride superconductive block is prepared by magnesium diffusion method using graphene in-stiu coating boron powder The method of material, includes the following steps：
(1) graphene oxide water solution is prepared by improved Hummers methods；
(2) graphene oxide water solution, boron powder and the deionized water that are prepared in the step (1) are uniformly mixed It closes, obtains boron powder and graphene oxide mixed solution, wherein the graphene oxide quality is the 10wt.% of boron silty amount；Into When row graphene oxide water solution, boron powder and deionized water are uniformly mixed, boron powder is taken to add in deionized water first, used Ultrasonic agitation and mechanical agitation, which are carried out at the same time, is disperseed, then lasting to be mixed, and obtains boron powder dispersion liquid；It measures a certain amount of The graphene oxide water solution prepared in the step (1), be slowly dropped into dropwise after being diluted and keep what is be mixed In boron powder dispersion liquid, until graphene oxide water solution is added dropwise, then stops ultrasonic agitation, obtain boron powder and graphite oxide Alkene mixed solution；The ultrasonic power preferably used is wherein stirred by ultrasonic as 1000W, continues mixing time as 24 hours；
(3) the boron powder prepared in the step (2) and graphene oxide mixed solution are placed in hydrothermal reaction kettle, control Hydrothermal temperature is 120 DEG C, and the hydro-thermal reaction duration is 6h, makes graphene oxide by thermal decomposition and reduction by hydro-thermal reaction For graphene, and make reduzate graphene and boron powder carries out compound, then combination product is centrifuged, precipitation is then taken to carry out Vacuum drying, obtains graphene in-stiu coating boron powder；
(4) with pressure forming method, the graphene in-stiu coating boron powder prepared in the step (3) is placed in mold In, presoma disk is pressed into hydraulic press, control pressing process pressure is 12MPa, continues dwell time 5min；
(5) it is 2 according to the atomic ratio of boron and magnesium:1 ratio, by the presoma block prepared in the step (4) with Magnesium powder is fitted into iron pipe, and iron pipe both ends are sealed, and obtains presoma block and the tubulature complex of boron powder mixing, then Using diffusion method, tubulature complex is placed in tubular type diffusion heat treatments stove, presoma block and boron powder are mixed under vacuum Object is heat-treated, and the vacuum degree of the vacuum is 3~8 × 10-3Pa, the thermal system for controlling diffusion heat treatments are heat treatment temperature It is 650 DEG C to spend, heat treatment heating rate be 10 DEG C/min, heat treatment soaking time be 1h, finally using cooling rate as 10 DEG C/ Min cools to room temperature with the furnace, obtains blocky mgb 2 superconductor.
The present embodiment experimental test and analysis：
For magnesium diboride bulk manufactured in the present embodiment in 20K, 3T, critical current density reaches 2.24 × 104A/cm2。
It is compound to stablizing for boron powder that the present embodiment by controllable graphene combination process realizes graphene, uniformly wraps It covers, avoids the contraction and reunion of graphene in conventional method, then prepare by magnesium diffusion method that crystal boundary connectivity is good, it is big to have Measure the compactness magnesium boride bulk of graphene pinning center.The present embodiment uses diffusion method, and diffusion method is the magnesium of melting or evaporation It diffuses into boryl body and reacts generation MgB2Technology, since its is simple for process, and MgB can be greatly reduced2Porosity, Crystal boundary connectivity is improved, increases critical current density, is to prepare fine and close MgB2The favorable method of block or wire rod.This implementation exists At a temperature of 650 DEG C of diffusion heat treatments, Mg is made uniformly to be diffused into presoma disk, obtain the magnesium diboride of distributed components Superconducting block makes doped source be evenly distributed, and is not in apparent volume contraction phenomenon, ensure that MgB2Block superconductor it is whole Body performance.
The embodiment of the present invention is illustrated above in conjunction with attached drawing, but the present invention is not limited to above-described embodiment, it can be with The purpose of innovation and creation according to the present invention makes a variety of variations, under the Spirit Essence and principle of all technical solutions according to the present invention Change, modification, replacement, combination or the simplification made, should be equivalent substitute mode, as long as meeting the goal of the invention of the present invention, The method for preparing magnesium diboride superconductive bulk by magnesium diffusion method using graphene in-stiu coating boron powder without departing from the present invention Technical principle and inventive concept, belong to protection scope of the present invention.

Claims (10)

1. a kind of method for preparing magnesium diboride superconductive bulk by magnesium diffusion method using graphene in-stiu coating boron powder, feature It is, includes the following steps：
(1) graphene oxide water solution is prepared；
(2) graphene oxide water solution, boron powder and the deionized water that are prepared in the step (1) are uniformly mixed, is obtained To boron powder and graphene oxide mixed solution；
(3) the boron powder prepared in the step (2) is placed in hydrothermal reaction kettle with graphene oxide mixed solution, passes through hydro-thermal Reaction makes graphene oxide by thermal decomposition and reduction be graphene, and it is compound to carry out reduzate graphene and boron powder, then will be again It closes product to centrifuge, then precipitation is taken to be dried in vacuo, obtain graphene in-stiu coating boron powder；
(4) the graphene in-stiu coating boron powder prepared in the step (3) is made to the presoma block of required shape；
(5) it is 2 according to the atomic ratio of boron and magnesium:1 ratio, by the presoma block prepared in the step (4) and magnesium powder It is fitted into iron pipe, and iron pipe both ends is sealed, obtain presoma block and the tubulature complex of boron powder mixing, then use Tubulature complex is placed in diffusion heat treatments stove, presoma block and boron powder is mixed under non-oxide protective atmosphere by diffusion method It closes object to be heat-treated, obtains blocky mgb 2 superconductor.
2. magnesium diboride superconductive bulk is prepared by magnesium diffusion method using graphene in-stiu coating boron powder according to claim 1 Method, which is characterized in that include the following steps：
(1) graphene oxide water solution is prepared；
(2) graphene oxide water solution, boron powder and the deionized water that are prepared in the step (1) are uniformly mixed, is obtained To boron powder and graphene oxide mixed solution, wherein the graphene oxide quality is 0.01~20wt.% of boron silty amount；
(3) the boron powder prepared in the step (2) is placed in hydrothermal reaction kettle with graphene oxide mixed solution, controls hydro-thermal Reaction temperature is 50~250 DEG C, and the hydro-thermal reaction duration is 5min~50h, graphene oxide is made to be heated by hydro-thermal reaction Decomposition-reduction is graphene, and it is compound that reduzate graphene is made to be carried out with boron powder, then combination product is centrifuged, Ran Houqu Precipitation is dried in vacuo, and obtains graphene in-stiu coating boron powder；
(4) the graphene in-stiu coating boron powder prepared in the step (3) is made to the presoma block of sheet；
(5) it is 2 according to the atomic ratio of boron and magnesium:1 ratio, by the presoma block prepared in the step (4) and magnesium powder It is fitted into iron pipe, and iron pipe both ends is sealed, obtain presoma block and the tubulature complex of boron powder mixing, then use Tubulature complex is placed in diffusion heat treatments stove, presoma block and boron powder is mixed under non-oxide protective atmosphere by diffusion method It closes object to be heat-treated, the thermal system for controlling diffusion heat treatments is that heat treatment temperature is 500~1200 DEG C, heat treatment heating speed Spend for 1~100 DEG C/min, heat treatment soaking time for 0.5~for 24 hours, be finally 1~100 DEG C/min with furnace cooling using cooling rate But to room temperature, blocky mgb 2 superconductor is obtained.
3. magnesium diboride superconductive bulk is prepared by magnesium diffusion method using graphene in-stiu coating boron powder according to claim 2 Method, which is characterized in that in the step (2), graphene oxide water solution, boron powder and deionized water are uniformly mixed Mode using any one or the two in ultrasonic agitation and mechanical agitation mixing mode.
4. magnesium diboride superconductive bulk is prepared by magnesium diffusion method using graphene in-stiu coating boron powder according to claim 3 Method, which is characterized in that in the step (2), graphene oxide water solution, boron powder and deionized water are uniformly mixed Mode using ultrasonic agitation and churned mechanically mixing mode, continue mixing time for 6~for 24 hours, wherein being stirred by ultrasonic The ultrasonic power used is 200~1000W.
5. magnesium diboride superconductive bulk is prepared by magnesium diffusion method using graphene in-stiu coating boron powder according to claim 4 Method, which is characterized in that in the step (2), carry out graphene oxide water solution, boron powder and deionized water carry out it is uniform During mixing, boron powder is taken to add in deionized water first, be carried out at the same time and disperseed using ultrasonic agitation and mechanical agitation, then held It is continuous to be mixed, obtain boron powder dispersion liquid；The graphene oxide water solution prepared in the step (1) is measured, is diluted It is slowly dropped into dropwise afterwards in the boron powder dispersion liquid for keeping being mixed, until graphene oxide water solution is added dropwise, then keep At least 5min is stirred by ultrasonic；Then stop ultrasonic agitation, obtain boron powder and graphene oxide mixed solution.
6. according to claim 1 or claim 2 prepare magnesium diboride superconductive using graphene in-stiu coating boron powder by magnesium diffusion method The method of bulk, which is characterized in that in the step (5), the non-oxide protective atmosphere for being diffused heat treatment uses inertia Protective gas atmosphere, restitutive protection's gas atmosphere or vacuum state environment.
7. magnesium diboride superconductive bulk is prepared by magnesium diffusion method using graphene in-stiu coating boron powder according to claim 2 Method, which is characterized in that in the step (2), control the graphene oxide quality be boron silty amount 3~ 10wt.%.
8. magnesium diboride superconductive bulk is prepared by magnesium diffusion method using graphene in-stiu coating boron powder according to claim 2 Method, which is characterized in that in the step (3), control hydrothermal temperature be 120~180 DEG C, hydro-thermal reaction continue when Between be 6~48h.
9. magnesium diboride superconductive bulk is prepared by magnesium diffusion method using graphene in-stiu coating boron powder according to claim 2 Method, which is characterized in that in the step (4), using pressure forming method, prepare the presoma block of sheet, control Pressing process pressure is 8.5~12MPa, continues 1~5min of the dwell time.
10. magnesium diboride superconductive block is prepared by magnesium diffusion method using graphene in-stiu coating boron powder according to claim 2 The method of material, which is characterized in that in the step (5), the thermal system for controlling diffusion heat treatments is heat treatment temperature 650 ~900 DEG C, heat treatment heating rate is 5~10 DEG C/min, and heat treatment soaking time is 1~10h, finally using cooling rate as 5 ~10 DEG C/min cools to room temperature with the furnace, obtains blocky mgb 2 superconductor.
CN201810086327.3A 2018-04-13 2018-04-13 The method for preparing magnesium diboride superconductive bulk by magnesium diffusion method using graphene in-stiu coating boron powder Pending CN108163867A (en)

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