KR20180131238A - Manufacturing method for MgB2 interactive mixture powder using wet mixing process, MgB2 interactive mixture powder and manufacturing method for superconducting wire unit uaing thereof - Google Patents

Abstract

The present invention relates to an MgB_2 interactive mixture power manufacturing method using a wet mixing process, MgB_2 interactive mixture power, and an MgB_2 superconducting wire rod manufacturing method using the same capable of providing interactive mixture powder having high apparent density by controlling relative sizes of Mg particles and B particles used in mixing, drying the Mg particles and the B particles after wetting and mixing the same with an organic solvent, and uniformly attaching the B particles to the Mg particles. The MgB_2 interactive mixture power manufacturing method using a wet mixing process comprises: a step of weighting and preparing Mg powder and B powder having predetermined different sizes; a step of inputting the weighted Mg powder and M powder to a stainless container with a ZrO_2 ball; a step of inputting the organic solvent to the stainless container and mixing the same; a step of forming interactive mixture powder by wetting and mixing the same with a 3D mixer; a step of pouring wet mixed slurry into the container, storing the same in a hood, and drying the same at room temperature; a step of separating a dried interactive mixture powder mass from the ball with a classifier; and a step of separating the dried interactive mixture powder mass into powder.

Description

Technical Field [0001] The present invention relates to a method for preparing an MgB2 intermixture powder by a wet mixing process, a MgB2 intermixture powder, and a method for manufacturing an MgB2 superconducting wire using the same thereof}

The invention MgB ₂ powder mixtures mutual manufacturing method using a wet-mixing process, and MgB ₂ powder mixtures each other and it relates to a MgB ₂ superconducting wire production method, particularly the critical current density (J _c) an improved PIT (Powder- in-Tube) to have an apparent density higher Mg and B for the production of superconducting wire of single-core or multi-core type is produced in a manner uniformly be powder coordinated by producing mutually mixture powder, flowable, MgB ₂ mutually mixture increased the charging rate And to a method for manufacturing MgB ₂ superconducting wire using the same.

Recently, MgB _{2, which} is a superconductor, has a high critical temperature (Tc) at a relatively low temperature and is manufactured by using magnesium powder (Mg) powder and boron (B) powder which are inexpensive as compared with Nb-Ti or Nb ₃ Sn , It is widely used as superconducting magnets for medical and research instruments such as MRI and NMR.

The MgB ₂ superconductor is manufactured in the form of a wire, a tape and a thin film. However, despite the excellent properties of MgB ₂ , it is not easy to improve the critical current characteristics in the manufacturing process.

A typical method of processing a MgB ₂ superconductor wire rod is a PIT (Powder In Tube) processing method. In this method, MgB ₂ mixed powder is charged into a metal tube to produce a wire rod through drawing, Thereby forming a wire rod.

However, such a conventional PIT (Powder In Tube) processing method has a disadvantage in that the charging capacity of the powder charged into the metal tube is insufficient and the charging rate is low, so that the current carrying ability is remarkably deteriorated.

The reason for the low charging rate of the powder charged into the metal tube is that since the Mg + B mixed powder has low apparent density and fluidity, it is difficult to uniformly charge the powder at the time of charging. As a result, uniformity and reproducibility of the superconducting wire having MgB ₂ phase It becomes difficult to secure.

The critical current density (J _c ) of the MgB ₂ superconducting wire fabricated by this method is lower than expected and the superconducting phenomenon is degraded.

Korean Patent Registration No. 10-1726732 (Apr. Korean Registered Patent Publication No. 10-0392511 (July 10, 2003) Korean Patent Registration No. 10-0524557 (October 21, 2005)

The object of the present invention is to adjust the relative sizes of Mg particles and B particles used for mixing, and wet-mix the particles with an organic solvent, and then dry the particles to uniformly adhere B particles to the Mg particles. And to provide a method for producing a mutual mixture powder having an apparent density and a manufacturing method thereof.

Another object of the present invention is by using a mutual mixture powder with a high bulk density using a PIT (Powder-In-Tube) was charged in the tube can powders configuration and flow, the critical current density by increasing manufacturing the charging rate (J _c ) Of the single-core or multi-core superconducting wire of the present invention.

According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, the method comprising: weighing and preparing Mg powder and B powder having different sizes;

Introducing the weighed Mg powder and B powder into a stainless vessel together with a ZrO ₂ ball;

Thereafter, pre-mixing the stainless steel container with an organic solvent;

And then wet mixed using a three-dimensional mixer to form an intermixed powder;

Then pouring the wet mixed slurry into the vessel and drying at ambient temperature while keeping it in the hood;

Separating the powder of the mutual mixture, which has been dried, from the ball using a classifier;

And then separating the dried mass of the mutually mixed powder into powders. The present invention also provides a method of preparing a mixed powder of MgB ₂ by a wet mixing process.

In a preferred embodiment, the Mg powder has a particle size of 45 to 75 mu m, and the B powder has a particle size of 0.35 mu m or less.

In a preferred embodiment, the Mg powder and the B powder can be weighed in a molar ratio of 1: 1.9 to 2.1.

In a preferred embodiment, the ZrO ₂ ball may be mixed so that the mixed Mg powder and B powder have a ball to powder ratio (BPR) of 1: 1 to 10: 1 by weight.

In a preferred embodiment, the organic solvent may contain 240 to 270 ml based on 100 g of mixed Mg powder and B powder using toluene.

In a preferred embodiment, the step of forming the intermixed powder may be wet blended for 4 to 8 hours.

According to another aspect of the present invention, there is provided an MgB ₂ mutual mixture powder characterized in that B particles are uniformly adhered to the periphery of Mg particles produced according to the above-described production method, and an apparent density is 0.58 to 0.61 g / cm ³ .

Further steps of the invention is charged to the apparent density of 0.58 ~ 0.61g / cm ³ mutually powder mixture prepared according to the method in Nb / Cu tube with another embodiment and;

Then, a single core wire is manufactured by a normal drawing process;

Followed by heat treatment in an inert gas atmosphere at 650 to 700 ° C for 30 to 60 minutes to form an MgB ₂ phase. The present invention provides a method for manufacturing an MgB ₂ superconducting wire.

In a preferred embodiment, the single core wire may be manufactured, and then the multi core wire may be manufactured by assembling the single core wire into a multi core wire and then drawing the MgB ₂ multi core wire.

In a preferred embodiment, the step of charging the intermixed powder into an Nb / Cu tube may be charged at a packing density of 0.6 to 0.7 g / cm ³ (relative density of 0.3 to 0.35).

In the method of producing an intermixture powder according to the present invention having the above-described characteristics, B particles are uniformly adhered to Mg particles so that the mixture looks like a simple substance, the apparent density is as high as 0.58 to 0.61 g / cm ³ , Advantages,

It is possible to fabricate superconducting core of high quality by improving the critical current density of the produced wire by showing the high filling rate when inserting these mixed powder into the Nb / Cu tube according to the PIT (Powder-In-Tube) Which is an industrially useful invention.

FIG. 1 is a view illustrating the structure of an MgB ₂ mutual mixture powder according to an embodiment of the present invention,
2 is a SEM photograph showing the surface states of the MgB ₂ mutual mixture powder and the non-mutual mixture powder according to an embodiment of the present invention.
FIG. 3 is a SEM photograph comparing the uniformity of the surface adhesion state of B particles according to the Mg particle size according to one embodiment of the present invention. FIG.
4 is a SEM photograph comparing the uniformity of B particles formed on the surface of Mg particles according to mixing time with an organic solvent according to an embodiment of the present invention,
FIG. 5 is a graph showing particle size analysis results between the MgB ₂ mutual mixture powder, the Mg raw powder, and the non-mutual mixture powder according to an embodiment of the present invention,
FIG. 6 is a SEM photograph showing the apparent density of MgB ₂ mixed powder, Mg powder and non-mixed powder after mixing according to the size of Mg particles according to an embodiment of the present invention,
FIG. 7 is a graph showing a critical current density when a superconducting wire is manufactured using an MgB ₂ mutual mixture powder and a non-mutual mixture powder according to an embodiment of the present invention.
FIG. 8 is a graph showing the critical current density when the superconducting multi-core wire is manufactured by classifying MgB ₂ mutual mixture powders according to an embodiment of the present invention,
FIG. 9 is an illustration showing an MgB ₂ phase formed at the time of manufacturing a superconducting core using an MgB ₂ mutual mixture powder according to an embodiment of the present invention. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is an explanatory diagram showing the structure of the MgB ₂ mutually mixture powder according to an embodiment of the invention, Figure 2 is shown the surface condition of the MgB ₂ cross the mixture powder and a non-cross-mixture powder in accordance with one embodiment of the present invention SEM picture.

In the present invention, in the mixing process of fine particles having different particle sizes, fine particles tend to adhere to the mother particles having a large particle size, and a method of forming Mg powder and B powder as an interactive mixture, When the mutual mixture powders are provided through such a method, the mixture looks like a simple substance, the bulk density is as high as 0.58 to 0.61 g / cm ³ , and the fluidity is improved. Thus, the mutual mixture powders are formed into Powder-In-Tube According to the method, a high charging rate is obtained when inserting the Nb / Cu tube, thereby ensuring the uniformity and reproducibility of the manufactured wire, thereby improving the critical current density and providing a quality superconducting core.

In the mixed powder according to the present invention, the B particles are uniformly adhered to the periphery of the Mg particles to have an apparent density of 0.58 to 0.61 g / cm ³ .

The method of preparing an intermixture powder according to an embodiment of the present invention includes preparing Mg powder and B powder by weighing them.

The Mg powder used for weighing has a particle size of 45 to 75 mu m, and the B powder has a particle size of 0.35 mu m or less.

The reason why the particle size of the Mg powder and the particle size of the B powder are relatively different and in particular, the particle size of the Mg powder is limited is that when the particles having such a size are used, In other words, when the 45 ~ 75μm Mg powder is applied, a highly homogeneous intermixture is formed, and the MgB ₂ multi-core wire is manufactured and the critical current density characteristics are improved.

The shape of the MgB ₂ mutual mixture differs depending on the particle size of the Mg powder. When the particle size is larger than the above-mentioned interval, the B particle adhesion amount increases, but the particle shape becomes uneven.

Specifically, when the Mg particle size of 25 mu m smaller than 45 mu m is used, the apparent density is 0.41, and when the Mg particle size is larger than 75 mu m and 150 mu m, the apparent density is 0.55 mu m, The average apparent density when the section is used has an apparent density smaller than 0.55 탆 and the uniformity is reduced. In particular, since the present invention exhibits an optimum bulk density of up to 0.61 mu m, it is very important to select the Mg particle size of the present invention to be 45 to 75 mu m.

The reason why the particle size of the B powder is limited to 0.35 탆 or less is that when the Mg particle size is 45 to 75 탆, the charged particle size satisfies the apparent density of 0.58 to 0.61 g / cm ³ . Particularly, the particle size of B was 1 ㎛, and when the particle size was similar to or larger than the Mg particle size, a mutual mixture powder in which B particle was adhered to the surface of Mg particle was not formed. Therefore, the size ratio between the Mg particles and the B particles according to the present invention is important.

Also, when the weighed amount of Mg powder and B powder is weighed at a molar ratio of 1: 1.9 to 2.1, the mutual mixing is most likely to occur. At the lower end of the gap, the B particles adhering to the surface of the Mg particles are not uniformly uniform. When the particles are out of the upper limit, the B particles not attached to the surface of the Mg particles remain.

And thereafter putting the weighed Mg powder and B powder into a stainless steel vessel together with a ZrO ₂ ball. At this time, the ZrO ₂ ball is added between the mixed powders of the weighed Mg powder and the B powder so that the ball to powder ratio (BPR) is 1: 1 to 10: 1 based on the weight ratio. When such a proportional section is present, the mixing result exhibits the most uniform mixing state.

Thereafter, the organic solvent is pre-mixed into the stainless steel container. Premixing is a mixing process that uses a spoon to minimize the aggregation of powder, balls and solvent.

The organic solvent used is 240 ~ 270 ml based on 100 g of Mg powder and B powder mixed with toluene.

Toluene is an oxygen-free organic solvent that acts as an oil to block or minimize the contact between the particle surface and oxygen. As a result, the deterioration of the properties of the mutual mixture is minimized and the mixing is performed well.

In addition, the reason for limiting the above-mentioned numerical values is that in order to mix the mixture, the mixture should be good. In order to accomplish this, the powder should be smoothly moved in the mixing process so that the mixing is good. When the amount of toluene is less than 240 ml Because the mixed powders are dyed like clay and adhere to the wall of the vessel, and the mixing between the powders is poor and the mixing becomes poor. In addition, when the amount of the solvent is more than 270 ml, the effect of increasing the mobility between powders does not occur any more, and it becomes too thin to increase the fluidity, which requires only unnecessary material cost and long time after mixing.

Thereafter, they are wet-mixed using a three-dimensional mixer to form an intermixed powder. Mix in the three-dimensional mixer for 4 to 8 hours. When mixing for less than 4 hours, sufficient B particles do not adhere to the surface of the Mg particles, and if they are mixed for more than 8 hours, since the B particles are sufficiently thick and uniformly adhered to the surface of the Mg particles, Is unnecessary.

Thereafter, the wet mixed slurry is poured into a vessel and dried at room temperature while being stored in a hood. In this case, it is enough to dry for 3 ~ 4 days. However, in case of less time, it is preferable to dry for more than 3 days because natural drying is not completed and moisture is left and powder separation is difficult.

Separating the dried powder of the mutually mixed powder from the ball using a classifier, and separating the dried powder of the mutually mixed powder into powder.

The MgB ₂ intermixture powders obtained by the above steps had an apparent density of 0.58-0.61 g / cm ³ , and the particle sizes of the MgB ₂ intermixture powder and the Mg raw powder and non-intermixed powder were compared with those of the initial powder A more uniform powder is obtained.

Hereinafter, a process for producing a superconducting core according to a conventional PIT (Powder-In-Tube) production method using an Interactive mixture powder prepared according to the above method will be described.

The MgB ₂ mutual mixture powder obtained through the above-described process is charged into the Nb / Cu tube at a packing density of 0.6 to 0.7 g / cm ³ (relative density of 0.3 to 0.35). At this time, since the MgB ₂ mutual mixture powder according to the present invention has an improved fluidity, the charging rate is increased and the charging is performed finely.

After that, a single core wire is produced by a normal drawing process

Thereafter, heat treatment is performed in an inert gas atmosphere at 650 to 700 ° C. for 30 to 60 minutes to form an MgB ₂ phase, thereby producing a core having improved superconducting characteristics (critical current density, Jc). This is because the MgB ₂ phase is uniformly formed because the B particles are uniformly attached to the surface of the Mg particles.

The manufacturing method may further include a step of manufacturing the single core wire, assembling the single core wire into the multi core wire, and then manufacturing the MgB ₂ multi core wire material by drawing.

FIG. 3 is a SEM photograph showing the uniformity of the surface adhesion state of the B particles according to the Mg particle size according to one embodiment of the present invention. It can be seen that the shape of the MgB ₂ mutual mixture varies depending on the particle size of the Mg powder. The larger the B particle adhesion amount is, the more the particle shape becomes uneven. Therefore, it can be seen that a very uniform MgB ₂ mutual mixture powder is obtained when the Mg powder having a particle size of 45 to 75 μm according to the present invention is used.

FIG. 4 is a SEM photograph showing the uniformity of B particles formed on the surface of Mg particles according to the mixing time with an organic solvent according to an embodiment of the present invention. The surface of the particles is observed, but it can be seen that B particles are uniformly thickly adhered when mixed for 8 hours. In addition, it can be seen that the shape of the MgB ₂ mutual mixture varies depending on the amount of toluene used as a medium in the wet mixing process.

FIG. 5 is a graph showing the results of particle size analysis between the MgB ₂ mutual mixture powder, the Mg raw powder, and the non-mutual mixture powder according to an embodiment of the present invention, wherein the Mg raw powder, the MgB ₂ mixed powder and the non- As a result of particle size analysis, it can be seen that the particle size of the mixed powder of MgB ₂ mixture is more uniform than that of the starting powder.

Figure 6 is the bulk density of the MgB ₂ powder mixture in one embodiment, SEM photographs comparing the apparent density between MgB ₂ mutually mixture powder after the mixing process in accordance with the Mg particles by size and Mg raw material powders, and a non-cross-mixture mixed powder according to the invention Is improved.

7 is MgB ₂ as applied to an embodiment MgB ₂ cross the mixture powder and a non-using mutual mixture powder as a comparative graph showing the critical current density when manufacturing a superconducting wire, mutually mixture powder mixture according to the invention The critical current densities of the bulk and wire rod were improved 1.1 times and 2 times, respectively.

FIG. 8 is a graph showing the critical current density when a superconducting multi-core wire is manufactured by classifying MgB ₂ mutual mixture powders according to an embodiment of the present invention. When a 45 to 75 μm Mg powder is applied, uniformity A very good intermixture was formed and MgB ₂ multi core wire was fabricated by using it. The critical current density was found to be the highest value.

9 is a graph showing the MgB ₂ phase formed at the time of manufacturing the superconducting core using MgB ₂ mutual mixture powders according to an embodiment of the present invention. )) MgB ₂ phase is formed by it can be seen that the MgB ₂ formed at a portion of the Mg and B particles contact.

The following is a preferred embodiment of the present invention.

(Example 1)

Mg and B powders were weighed in a ratio of 1: 2.1 in a ratio of 100 g to an SUS vessel containing 100 g of balls corresponding to 1: 1 ZrO ₂ BPR (Ball to Powder ratio). At this time, the size of the Mg particles was 45 to 75 mu m, and the size of the B particles was 0.35 mu m.

Then 240 ml of organic solvent toluene is added and pre-mixing is performed.

After mixing for 4 hours using a three-dimensional mixer, the mixed slurry is poured into a container and stored at room temperature for 3 days at room temperature.

The dried powder is separated from the ball using a classifier and pulverized into a dried mass.

The apparent density of the intermixed mixture after the wet mixing process was 0.58-0.61 g / cm ³ .

(Example 2)

Mg and B powders were weighed to a molar ratio of 1: 1.9, and charged into a SUS vessel containing 1000 g of balls corresponding to a ZrO ₂ BPR (Ball to powder ratio) of 10: 1. At this time, the size of the Mg particles was 45 to 75 mu m, and the size of the B particles was 0.35 mu m.

Then 270 ml of organic solvent toluene is added and pre-mixing is performed.

After mixing for 4 hours using a three-dimensional mixer, the mixed slurry is poured into a container and stored at room temperature for 3 days at room temperature.

The dried powder is separated from the ball using a classifier and pulverized into a dried mass.

The apparent density of the intermixed mixture after the wet mixing process was 0.58-0.61 g / cm ³ .

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents. Of course, such modifications are within the scope of the claims.

Claims (10)

Preparing Mg powder and B powder having different sizes by weighing;
Introducing the weighed Mg powder and B powder into a stainless vessel together with a ZrO ₂ ball;
Thereafter, pre-mixing the stainless steel container with an organic solvent;
And then wet mixed using a three-dimensional mixer to form an intermixed powder;
Then pouring the wet mixed slurry into the vessel and drying at ambient temperature while keeping it in the hood;
Separating the powder of the mutual mixture, which has been dried, from the ball using a classifier;
And then separating the dried mass of the mutually mixed powder into powders. The method for producing an MgB2 mutual mixture powder according to claim _1,
The method according to claim 1,
The particle size of the Mg powder and the 45 ~ 75㎛, MgB ₂ powder mixtures inter method using a wet mixing process, characterized by using that 0.35㎛ or less the particle size of the powder B using that.
The method of claim 2,
The Mg powder and the B powder is 1: 1.9 ~ MgB ₂ powder mixtures inter method using a wet mixing process, characterized in that the weighed and added to 2.1 molar ratio.
The method according to claim 1,
The ZrO ₂ ball is BPR (Ball to powder ratio) 1 to the mixed Mg powder and B powder has a weight ratio: the powder method MgB ₂ cross the mixture using a wet-mixing process, it characterized in that the input to be 1: 1-10.
The method according to claim 1,
Wherein the organic solvent comprises 240 to 270 ml based on 100 g of the Mg powder mixed with toluene and the B powder, and the method for preparing the mixed powder of MgB ₂ using the wet mixing process.
The method according to claim 1,
Forming the cross-powder mixture is MgB ₂ powder mixtures inter method using a wet mixing process, characterized in that wet mixing for 4 to 8 hours.
7. An MgB ₂ intermixture powder characterized in that B particles are uniformly adhered to the periphery of Mg particles produced by the manufacturing method according to any one of claims 1 to 6, and an apparent density is 0.58 to 0.61 g / cm ³ .
Charging an Nb / Cu tube with an intermixed powder having an apparent density of from 0.58 to 0.61 g / cm ³ produced according to the method of any one of claims 1 to 6;
Then, a single core wire is manufactured by a normal drawing process;
MgB ₂ superconducting wire production method according to claim consisting of; after 650 ~ 700 ℃, 30 ~ 60 minutes to a heat treatment in an inert gas atmosphere to form a MgB ₂ phase while.
The method of claim 8,
The method of manufacturing a MgB ₂ superconducting wire according to claim ₁ , further comprising the step of fabricating the single core wire, assembling the single core wire into a multi core wire and then drawing the MgB ₂ multi core wire material by drawing.
The method of claim 8,
The method comprising the mutual mixture powder charged into a Nb / Cu tube is MgB ₂ superconducting wire production method characterized in that the contents in the packing density 0.6 ~ 0.7 g / cm ³ (relative density of 0.3 ~ 0.35).

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