Preparation method of ErBCO superconducting target material

Abstract

The invention provides a preparation method of an ErBCO superconducting target, and belongs to the technical field of oxide target materials.The preparation method comprises the steps that firstly, erbium nitrate, barium nitrate, copper nitrate, high-purity water, a dispersing agent and a binding agent are sequentially mixed, and then mixed powder is obtained through segmented ball milling and spray granulation; then the ErBCO superconducting target material is prepared through the method that the mixed powder is sequentially subjected to calcination, cold sintering and drying treatment, the effect of reducing the cost while the performance such as the density of the target material is improved is achieved through the cold sintering process, and the ErBCO superconducting target material has the advantages that the ceramic sintering temperature is remarkably reduced, and the sintering time is remarkably shortened.

Description

Technical Field

[0001] The invention relates to the technical field of oxide target materials, and in particular to a method for preparing an ErBCO superconducting target material. Background Art

[0002] Superconducting materials have a series of advantages such as strong current carrying capacity and low loss. They have a wide range of applications and play an important role in their application scenarios. At present, the superconducting target material is mainly YBCO target material, and its preparation methods mainly include vacuum or normal pressure sintering, cold pressing, etc. However, the vacuum sintering and normal pressure sintering times are relatively long, and the density of the obtained target material is not high. Although hot pressing sintering can shorten the sintering time, its use cost is relatively high.

[0003] For example, although patent CN116023127A discloses a YBCO target material with an initial density of 95% prepared by spark plasma assisted hot pressing sintering and cold pressing, its cost is relatively high; patent CN101492291A discloses a YBCO target material prepared by cold isostatic pressing followed by normal pressure sintering to obtain a YBCO target material with a superconducting phase structure, but the density of the prepared target material is relatively poor.

[0004] Cold sintering is a new concept in the preparation of low-carbon ceramics. It first mixes ceramic powder with a certain intermediate liquid phase, pours it into a customized mold, and then applies a certain uniaxial pressure and sinters it to obtain dense ceramics. This achieves the effect of making ceramic powder able to be prepared at a densification temperature of ≤300℃.

[0005] At the same time, due to the complex physical mechanism of high-temperature superconductors, some superconducting phenomena are difficult to explain based on existing theories, and the electromagnetic properties of superconducting materials are greatly affected by external magnetic fields, temperature, mechanical and other factors. As a result, there are many technical difficulties in the application of high-temperature superconducting materials. However, studies have shown that compared with other types of ceramics, Er-123 is the best attenuator for gamma radiation.

[0006] In summary, the existing target material preparation methods still have the defect of not being able to simultaneously improve the target material density and reduce the cost. Therefore, how to use the cold sintering process to prepare a new type of ErBCO superconducting target material with low cost and high density has become a technical problem that needs to be solved urgently and a research hotspot. Summary of the invention

[0007] In view of this, in order to overcome and remedy the above-mentioned shortcomings and deficiencies in the prior art, the present invention provides a method for preparing an ErBCO superconducting target material, and prepares a new type of ErBCO superconducting target material by using a cold sintering process, which greatly reduces the ceramic sintering temperature and significantly shortens the sintering time, thereby achieving the effect of improving the density and other properties of the target material while reducing the cost.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing an ErBCO superconducting target material, comprising the following preparation steps:

[0010] 1) erbium nitrate, barium nitrate, copper nitrate, high-purity water, a dispersant and a binder are sequentially mixed, and then subjected to segmented ball milling and spray granulation to obtain a mixed powder;

[0011] 2) calcining the mixed powder once to obtain single-phase ErBCO powder;

[0012] 3) cold sintering and drying the single-phase ErBCO powder to obtain the ErBCO superconducting target;

[0013] The cold sintering specifically includes: grinding and mixing the single-phase ErBCO powder and the auxiliary liquid, placing the powder in a mold for pressing and forming, and cold sintering at 100-500° C. for 1-5 hours.

[0014] Preferably, the segmented ball milling in step 1) specifically comprises: firstly mixing erbium nitrate, barium nitrate, copper nitrate, high-purity water and a dispersant and then ball milling for 20-24 hours, then adding a binder and continuing ball milling for 1-4 hours.

[0015] Preferably, the grinding balls in the segmented ball mill include zirconium oxide ceramic balls or aluminum oxide ceramic balls; the content of the grinding balls is 40-60%.

[0016] Preferably, in step 1), the dispersant is a solution with a pH of 7 prepared from polyacrylic acid, ammonia water, pure water and n-octanol; the content of the dispersant is 0.5-1.0%.

[0017] Preferably, in step 1), the binder comprises polyvinyl alcohol; the content of the binder is 0.5-1.0%.

[0018] Preferably, in step 1), the molar ratio of erbium nitrate, barium nitrate and copper nitrate is 1:2:3.

[0019] Preferably, the solid content of the mixed powder in step 1) is 50-55%.

[0020] Preferably, in step 2), the calcination temperature is 800-1200° C. and the calcination time is 5-10 h.

[0021] Preferably, the auxiliary liquid in step 3) comprises deionized water or acetic acid solution; the mass fraction of the auxiliary liquid is 2wt.%-30wt.%.

[0022] The present invention also provides an ErBCO superconducting target material prepared according to the above preparation method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The invention adopts a method that erbium nitrate, barium nitrate, copper nitrate, high-purity water, a dispersant and a binder are mixed in sequence, and then subjected to segmented ball milling and spray granulation to obtain a mixed powder. The mixed powder is then subjected to calcination, cold sintering and drying in sequence to prepare an ErBCO superconducting target material. The cold sintering process is used to improve the density and other properties of the target material while reducing the cost. The invention has the advantages of significantly reducing the ceramic sintering temperature and shortening the sintering time.

[0025] Compared with the traditional method, the present invention prepares a high-density ErBCO superconducting target material through cold sintering technology, which effectively prevents the loss of volatile elements during the ceramic densification process, thereby achieving the effect of precise control of the ceramic shrinkage rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the process flow of the ErBCO target material preparation method in Examples 1-3 of the present invention;

[0027] Figure 2 is a SEM image of the ErBCO target prepared in Example 1 of the present invention;

[0028] Figure 3 XRD pattern of the ErBCO target prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing an ErBCO superconducting target material, comprising the following preparation steps:

[0030] 1) erbium nitrate, barium nitrate, copper nitrate, high-purity water, a dispersant and a binder are sequentially mixed, and then subjected to segmented ball milling and spray granulation to obtain a mixed powder;

[0031] 2) calcining the mixed powder once to obtain single-phase ErBCO powder;

[0032] 3) cold sintering and drying the single-phase ErBCO powder to obtain the ErBCO superconducting target;

[0033] The cold sintering is preferably as follows: after the single-phase ErBCO powder and the auxiliary liquid are ground and mixed, they are placed in a mold for pressing and forming, and cold sintered at 100-500° C. for 1-5 hours;

[0034] The invention prepares mixed powder by mixing erbium nitrate, barium nitrate, copper nitrate, high-purity water, dispersant and binder in sequence, and then performing segmented ball milling and spray granulation.

[0035] In the present invention, the molar ratio of erbium nitrate, barium nitrate and copper nitrate is preferably 1:2:3, the purity is preferably 4N, and the particle size range is preferably 50-500nm; the solid content of the mixed powder is preferably 50-55%, more preferably 52%;

[0036] The dispersant is preferably a solution with a pH of 7 prepared from polyacrylic acid, ammonia water, pure water and n-octanol; the content of the dispersant is preferably 0.5-1.0%, more preferably 0.7%; the binder is preferably polyvinyl alcohol; the content of the binder is preferably 0.5-1.0%, more preferably 0.7%.

[0037] The specific process of the segmented ball milling of the present invention is preferably as follows: firstly, erbium nitrate, barium nitrate, copper nitrate, high-purity water and a dispersant are mixed and then wet-milled for 20-24 hours, and then a binder is added and the ball milling is continued for 1-4 hours;

[0038] The grinding balls used in the segmented ball milling of the present invention are preferably zirconia ceramic balls or alumina ceramic balls, and their diameter range is preferably 1-10 mm, the diameter difference is preferably 1-3 mm, and the mass ratio of large, medium and small balls is preferably 1:1:1; the content of grinding balls in the segmented ball milling process is preferably 40-60%, more preferably 55%; the air inlet temperature of the granulation equipment is preferably 190-220°C, and the feed speed is preferably 10-20r / min.

[0039] After obtaining the mixed powder, the present invention calcines the mixed powder once to obtain single-phase ErBCO powder, and obtains the ErBCO superconducting target by cold sintering and drying the single-phase ErBCO powder.

[0040] During the initial pressurization stage of the cold sintering process described in the present invention, stress concentration occurs in the particle-particle contact area, and the contact pressure will be much higher than the external pressure, which may cause the particles to yield and undergo plastic deformation. At this time, the auxiliary liquid added in the present invention can act as a lubricant, thereby reducing friction between particles, improving particle rearrangement efficiency, and promoting densification.

[0041] In the technical solution of the present invention, the presence of liquid phase and auxiliary pressure is beneficial to the dissolution of particle tips, particle rearrangement and mass transfer; under the action of auxiliary pressure and heat source, the liquid phase evaporates or is discharged to form a supersaturated solution and precipitate, filling the surface or gap of the particles, and sintering the powder into a ceramic block with a dense structure.

[0042] In the step 2) of the present invention, the calcination temperature is preferably 800-1200° C., more preferably 900° C.; the calcination time is preferably 5-10 h, more preferably 10 h; the auxiliary liquid in the step 3) is preferably deionized water or acetic acid solution, more preferably deionized water; the mass fraction of the auxiliary liquid is preferably 2wt.%-30wt.%, more preferably 10wt.%.

[0043] The invention adopts a method that erbium nitrate, barium nitrate, copper nitrate, high-purity water, a dispersant and a binder are mixed in sequence, and then subjected to segmented ball milling and spray granulation to obtain a mixed powder. The mixed powder is then subjected to calcination, cold sintering and drying in sequence to prepare an ErBCO superconducting target material. The cold sintering process is used to improve the density and other properties of the target material while reducing the cost. The invention has the advantages of significantly reducing the ceramic sintering temperature and shortening the sintering time.

[0044] The present invention adopts a solid phase reaction method to prepare ErBCO powder, and obtains a target material by placing the ErBCO powder in a mold for cold sintering. Compared with the traditional method, the present invention prepares a high-density ErBCO superconducting target material through cold sintering technology, effectively preventing the loss of volatile elements during the ceramic densification process, thereby achieving the effect of accurately controlling the ceramic shrinkage rate.

[0045] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0046] Example 1

[0047] The preparation method of the ErBCO superconducting target material in this embodiment includes the following steps:

[0048] 1) First, erbium nitrate, barium nitrate, and copper nitrate powders are mixed in a molar ratio of 1:2:3, and then high-purity water and a dispersant are added and mixed to obtain a mixture; the obtained mixture is placed in a ball mill and ball milled for 20 hours, and then a binder is added and ball milled for 2 hours to obtain a mixed slurry; finally, the mixed slurry is atomized and dried by a spray granulation device to obtain a granulated mixed powder;

[0049] The solid content of the mixed powder is 52%, the content of the grinding balls used in the ball milling process is 50%, the content of the dispersant is 0.7%; the content of the binder is 0.5%; the purity of the erbium oxide, barium carbonate and copper oxide powders is 4N (99.99%); the particle size of the erbium oxide, barium carbonate and copper oxide powders is 50-150nm; the grinding balls used in the ball milling process are zirconia ceramic balls, and the diameters of the large balls, medium balls and small balls are 10mm, 5mm and 3mm respectively, and the mass ratio of the large, medium and small balls is 1:1:1; the rotation speed of the ball mill is 90r / min; the air inlet temperature of the granulation equipment is set to 210°C, and the feed speed is set to 15r / min.

[0050] 2) The mixed powder is calcined in air at a temperature of 900° C. for 10 h to obtain ErBCO powder having a superconducting phase.

[0051] 3) 10 wt.% of deionized water was added to the above ErBCO powder for grinding, and the evenly ground powder was placed in a cold sintering mold and pressed under a pressure of 200 MPa. When the pressure reached the maximum load, the pressure was continuously applied, and cold sintering was performed at 200° C. for 1.5 h. After the cold sintering was completed, the cold sintered sample was taken out and dried in an oven for 48 h to obtain the ErBCO superconducting target.

[0052] Figure 1 Schematic diagram of the process flow of the ErBCO target material preparation method in Examples 1-3 of the present invention;

[0053] Figure 2 is a SEM image of the ErBCO target prepared in Example 1 of the present invention;

[0054] Figure 3 XRD pattern of the ErBCO target prepared in Example 1 of the present invention.

[0055] Depend on Figure 1-3 It can be seen that the present invention provides a method for preparing an ErBCO superconducting target material, which comprises first mixing erbium nitrate, barium nitrate, copper nitrate, high-purity water, a dispersant and a binder in sequence, and then subjecting the mixed powder to segmented ball milling and spray granulation to obtain a mixed powder. Subsequently, the mixed powder is sequentially subjected to the steps of calcination, cold sintering and drying to prepare a novel ErBCO superconducting target material, which achieves the effect of reducing costs while improving the properties of the target material such as density, and has the advantages of significantly reducing the ceramic sintering temperature and shortening the sintering time.

[0056] Example 2

[0057] The preparation method of the ErBCO superconducting target material in this embodiment includes the following steps:

[0058] 1) First, erbium nitrate, barium nitrate, and copper nitrate powders are mixed in a molar ratio of 1:2:3, and then high-purity water and a dispersant are added and mixed to obtain a mixture; the obtained mixture is placed in a ball mill and ball milled for 20 hours, and then a binder is added and ball milled for 2 hours to obtain a mixed slurry; finally, the mixed slurry is atomized and dried by a spray granulation device to obtain a granulated mixed powder;

[0059] The solid content of the mixed powder is 55%, the content of the grinding balls used in the ball milling process is 50%, the content of the dispersant is 0.7%; the content of the binder is 0.7%; the purity of the erbium oxide, barium carbonate and copper oxide powders is 4N (99.99%); the particle size of the erbium oxide, barium carbonate and copper oxide powders is 50-150nm; the grinding balls used in the ball milling process are zirconia ceramic balls, and the diameters of the large balls, medium balls and small balls are 10mm, 5mm and 3mm respectively, and the mass ratio of the large, medium and small balls is 1:1:1; the rotation speed of the ball mill is 90r / min; the air inlet temperature of the granulation equipment is set to 210°C, and the feed speed is set to 15r / min.

[0060] 2) The mixed powder is calcined in air at a temperature of 900° C. for 10 h to obtain ErBCO powder having a superconducting phase.

[0061] 3) Add 7 wt.% of deionized water to the above ErBCO powder for grinding, and place the evenly ground powder in a cold sintering mold and apply a pressure of 200 MPa to press molding. When the pressure reaches the maximum load, continue to apply pressure and cold sinter for 1.5 hours at 300°C; after the cold sintering is completed, take out the cold sintered sample and dry it in an oven for 48 hours to obtain the ErBCO superconducting target.

[0062] Example 3

[0063] The preparation method of the ErBCO superconducting target material in this embodiment includes the following steps:

[0064] 1) First, erbium nitrate, barium nitrate, and copper nitrate powders are mixed in a molar ratio of 1:2:3, and then high-purity water and a dispersant are added and mixed to obtain a mixture; the obtained mixture is placed in a ball mill and ball milled for 20 hours, and then a binder is added and ball milled for 2 hours to obtain a mixed slurry; finally, the mixed slurry is atomized and dried by a spray granulation device to obtain a granulated mixed powder;

[0065] The solid content of the mixed powder is 58%, the content of the grinding balls used in the ball milling process is 50%, and the content of the dispersant is 0.7%; the content of the binder is 1.0%; the purity of the erbium oxide, barium carbonate and copper oxide powders is 4N (99.99%); the particle size of the erbium oxide, barium carbonate and copper oxide powders is 50-150nm; the grinding balls used in the ball milling process are zirconia ceramic balls, and the diameters of the large balls, medium balls and small balls are 10mm, 5mm and 3mm respectively, and the mass ratio of the large, medium and small balls is 1:1:1; the rotation speed of the ball mill is 90r / min; the air inlet temperature of the granulation equipment is set to 210°C, and the feed speed is set to 15r / min.

[0066] 2) The mixed powder is calcined in air at a temperature of 900° C. for 10 h to obtain ErBCO powder having a superconducting phase.

[0067] 3) Add 25wt.% acetic acid solution to the above ErBCO powder for grinding, and place the evenly ground powder in a cold sintering mold and apply a pressure of 200MPa to press molding. When the pressure reaches the maximum load, continue to apply pressure and cold sinter at 250°C for 1h. After the cold sintering is completed, take out the cold sintered sample and dry it in an oven for 48h to obtain the ErBCO superconducting target.

[0068] In summary, the present invention adopts the method of first mixing erbium nitrate, barium nitrate, copper nitrate, high-purity water, a dispersant and a binder in sequence, and then subjecting the mixed powder to segmented ball milling and spray granulation to sequentially calcination, cold sintering and drying treatment to prepare a novel ErBCO superconducting target material. The present invention uses Er as a ceramic raw material and combines the cold sintering process to achieve the effect of improving the density and other properties of the target material while reducing the cost, and has the advantages of significantly reducing the ceramic sintering temperature and shortening the sintering time.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an ErBCO superconducting target, characterized in that: The method comprises the following preparation steps: 1) erbium nitrate, barium nitrate, copper nitrate, high-purity water, a dispersant and a binder are sequentially mixed, and then subjected to segmented ball milling and spray granulation to obtain a mixed powder; 2) calcining the mixed powder once to obtain single-phase ErBCO powder; 3) cold sintering and drying the single-phase ErBCO powder to obtain the ErBCO superconducting target; The cold sintering specifically includes: grinding and mixing the single-phase ErBCO powder and the auxiliary liquid, placing the powder in a mold for pressing and forming, and cold sintering at 100-500° C. for 1-5 hours.

2. The preparation method according to claim 1, characterized in that: The segmented ball milling in step 1) specifically includes: firstly mixing erbium nitrate, barium nitrate, copper nitrate, high-purity water and a dispersant and then ball milling for 20-24 hours, then adding a binder and continuing ball milling for 1-4 hours.

3. The preparation method according to claim 2, characterized in that: The grinding balls in the segmented ball mill include zirconium oxide ceramic balls or aluminum oxide ceramic balls; the content of the grinding balls is 40-60%.

4. The preparation method according to claim 1, characterized in that: In the step 1), the dispersant is a solution with a pH of 7 prepared from polyacrylic acid, ammonia water, pure water and n-octanol; the content of the dispersant is 0.5-1.0%.

5. The preparation method according to claim 1, characterized in that: In the step 1), the binder comprises polyvinyl alcohol; the content of the binder is 0.5-1.0%.

6. The preparation method according to claim 1, characterized in that: In the step 1), the molar ratio of erbium nitrate, barium nitrate and copper nitrate is 1:2:

3.

7. The preparation method according to claim 1, characterized in that: The solid content of the mixed powder in step 1) is 50-55%.

8. The preparation method according to claim 1, characterized in that: In the step 2), the calcination temperature is 800-1200° C. and the calcination time is 5-10 hours.

9. The preparation method according to claim 1, characterized in that: In step 3), the auxiliary liquid comprises deionized water or acetic acid solution; the mass fraction of the auxiliary liquid is 2wt.%-30wt.%.

10. An ErBCO superconducting target prepared by the method according to any one of claims 1 to 9.

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