Preparation method of low-cost Bi-series superconducting powder
By using oxides and nitrates or carbonates as raw materials, combined with freeze drying and one-step heat treatment, the problems of high cost and environmental pollution in the preparation of Bi-based superconducting powders are solved, and efficient and low-cost preparation of high-phase purity powders is achieved.
Patent Information
- Application Number
- CN202511206781.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-27
- Publication Date
- 2025-10-10
AI Technical Summary
The existing process for preparing Bi-based high-temperature superconducting powders is long, costly, and has environmental pollution problems.
The most primitive precursor oxides and nitrates or carbonates are used as raw materials, combined with freeze drying and one-step heat treatment to avoid reaction aggregation effects, reduce impurities, and obtain high-phase-purity Bi-based superconducting powder.
It has achieved low-cost and efficient preparation of high-phase-purity Bi-based superconducting powder, simplified the process, reduced energy consumption and minimized environmental pollution.
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of high-temperature superconducting materials, and particularly relates to a preparation method of low-cost Bi-based superconducting powder. BACKGROUND
[0002] Bi-based high-temperature superconducting materials (Bi2223, Bi2212) have good current-carrying performance in the liquid nitrogen temperature zone and low-temperature high magnetic field, and are one of the current research hotspots in the superconducting field. High-performance Bi-based precursor powder is particularly important in the online tape preparation process, and is a prerequisite for obtaining high current-carrying performance Bi-based high-temperature superconducting tapes.
[0003] In order to obtain high-performance powder, researchers have developed various powder preparation technologies, such as melt casting process, coprecipitation technology, ultrasonic spray pyrolysis technology, spray drying technology, etc. By optimizing the preparation process parameters, the precursor powder meeting the technical requirements can be obtained. However, these technologies have the disadvantages of long preparation process and high cost. For example, in the process of preparing Bi2212 powder by using the melt casting method, oxide powders of Bi, Sr, Ca, Cu, etc. are generally subjected to high-temperature melting treatment to obtain an intermediate phase, the intermediate phase is ground and then subjected to multi-step sintering heat treatment to obtain a bulk body, and finally the bulk body is ground and crushed to obtain the precursor powder. In the melt casting process, a relatively high melting heat treatment needs to be introduced, and subsequent multi-step heat treatment is required, which has a long heat treatment time and high overall energy consumption. Ultrasonic spray pyrolysis, spray drying, etc. generally need to dissolve oxides, carbonates and copper metals in nitric acid to prepare a nitrate solution, and then pass through a spray pyrolysis or drying device to obtain green powder; the green powder is generally subjected to 3-step heat treatment to obtain the precursor powder. The coprecipitation technology is to dissolve oxides, carbonates or copper metals in nitric acid, and then add oxalate ethanol for precipitation, and then perform multi-step grinding and heat treatment on the oxalate precipitate to obtain the precursor powder. The coprecipitation technology generally needs 7-9 steps of heat treatment to obtain good powder. These powder preparation processes generally introduce nitric acid, which causes environmental pollution during the dissolution process. At the same time, relatively expensive equipment is generally used, and if one-step heat treatment is used, reaction aggregation effect is generally generated, which is generally solved by decomposing into multi-step heat treatment and multi-step grinding. These processes have long overall process time and high cost. SUMMARY
[0004] The technical problem to be solved by the present application is to provide a preparation method of low-cost Bi-based superconducting powder to solve the problems of long preparation process, high cost and environmental pollution of the existing Bi-based superconducting powder preparation process. The method directly reacts with the most original precursor, realizes rapid one-step heat treatment by combining freeze drying, reduces the particle size of the phase formation powder, avoids the aggregation effect in the reaction process, reduces the residual impurity phase, obtains high phase purity, has a simple process flow and is more environmentally friendly.
[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a preparation method of low-cost Bi-based superconducting powder, characterized in that the method comprises the following steps: Step one, bismuth oxide, strontium carbonate, calcium carbonate and copper oxide are mixed according to the atomic ratio Bi:Sr:Ca:Cu=(2+x):(2-y):(1-y):2, wherein x=0.05~0.2, y=0.05~0.15, and then grinding to obtain mixture 1#; Or bismuth oxide, strontium nitrate, calcium carbonate and copper oxide are mixed according to the atomic ratio Bi:Sr:Ca:Cu=(2+x):(2-y):(1-y):2, wherein x=0.05~0.2, y=0.05~0.15, and then grinding to obtain mixture 2#; Or bismuth oxide, lead nitrate, strontium carbonate, calcium carbonate and copper oxide are mixed according to the atomic ratio Bi:Pb:Sr:Ca:Cu=1.8:0.3:2:2:3, and then grinding to obtain mixture 3#; Or bismuth oxide, lead nitrate, strontium nitrate, calcium carbonate and copper oxide are mixed according to the atomic ratio Bi:Pb:Sr:Ca:Cu=1.8:0.3:2:2:3, and then grinding to obtain mixture 4#; Step two, the mixture 1#, mixture 2#, mixture 3# or mixture 4# obtained in step one is mixed with a polymer and a solvent according to the mass ratio 1:a:b, wherein a=0.02~0.3, b=4~20, to obtain mixed slurry 1#, mixed slurry 2#, mixed slurry 3# or mixed slurry 4# respectively; Step three, the mixed slurry 1#, mixed slurry 2#, mixed slurry 3# or mixed slurry 4# obtained in step two is freeze-dried to obtain porous blank 1#, porous blank 2#, porous blank 3# or porous blank 4# respectively; Step four, the porous blank 1#, porous blank 2#, porous blank 3# or porous blank 4# obtained in step three is heat-treated to obtain Bi-based superconducting powder.
[0006] Different from the traditional Bi-based superconducting powder preparation method, the precursor powder is mixed and heat treated directly, which causes the reaction aggregation effect in the powder, easily produces large size second phase and has the disadvantage of extremely low phase purity, the oxide, nitrate or carbonate precursor powder is selected for grinding and mixing in the application, without introducing the solvent such as nitric acid, the preparation method is simple, and the low cost advantage is obtained; then the pores in the powder are increased through freeze drying, the agglomeration is inhibited, the porous blank is obtained, the aggregation effect in the reaction process is avoided, the residual impurity phase in the phase formation process is reduced, the higher phase purity is obtained, the grain overgrowth is inhibited, and then the step of rapid heat treatment is carried out, the particle size of the phase formation powder is reduced, and the Bi-based superconducting powder can be obtained.
[0007] The preparation method of the low-cost Bi-based superconducting powder has the characteristics that in the step two, the polymer is sodium carboxymethyl cellulose or ethyl cellulose, the solvent is water, ethanol or tert-butanol, the stirring speed is 300 rpm to 30000 rpm, and the time is 1 min to 5 min. Preferably, the water-based mixed slurry is obtained by using the polymer sodium carboxymethyl cellulose and the solvent water, or the alcohol-based mixed slurry is obtained by using the polymer ethyl cellulose and the solvent ethanol or tert-butanol.
[0008] The preparation method of the low-cost Bi-based superconducting powder has the characteristics that in the step three, the freeze drying process is: cooling in liquid nitrogen, and the freeze drying conditions are: vacuum degree 1 Pa and temperature-80 DEG C.
[0009] The preparation method of the low-cost Bi-based superconducting powder has the characteristics that in the step four, the heat treatment temperature of the porous blank 1# and the porous blank 2# is 840 DEG C to 860 DEG C, and the time is 1 h to 10 h, the heat treatment temperature of the porous blank 3# and the porous blank 4# is 800 DEG C to 810 DEG C, and the time is 1 h to 10 h. The porous blank 1# and the porous blank 2# belong to Bi2212 blank, and the heat treatment temperature is higher, the porous blank 3# and the porous blank 4# belong to Bi2223 blank, and the heat treatment temperature is lower.
[0010] Compared with the prior art, the application has the following advantages: 1. The application uses the original precursor oxide and nitrate or carbonate as raw materials for reaction, combines freeze drying and heat treatment, effectively inhibits agglomeration, optimizes reaction space, reduces the particle size of phase formation powder, avoids the aggregation effect in the reaction process, reduces residual impurity phase, obtains higher phase purity, and realizes the preparation of high-performance and low-cost Bi-based superconducting powder.
[0011] 2、The mixture precursor in the application adopts a small amount of nitrate and carbonate to adjust the phase reaction speed, and in the subsequent heat treatment phase reaction process, bismuth oxide usually reacts with nitrate or carbonate in the early stage of the reaction, because the decomposition reaction temperature of strontium nitrate and calcium nitrate is relatively low (570 DEG C and 561 DEG C respectively), and the decomposition temperature of strontium carbonate and calcium carbonate is relatively high (1100 DEG C and 825 DEG C respectively), so the reaction of nitrate is relatively violent, and the reaction of carbonate is relatively slow, by adjusting the content of nitrate and carbonate, combining with the control of heat treatment temperature, the phase reaction speed is controlled, so as to promote the phase of Bi-based precursor powder and improve the uniformity of Bi-based superconducting powder.
[0012] 3、The application adopts oxide and nitrate or carbonate as raw materials, without introducing nitric acid and other solvents, and is more environmentally friendly.
[0013] 4、The carbonate used in the application directly reacts with the precursor oxide including copper oxide and bismuth oxide at a relatively low temperature, avoiding high temperature required for direct decomposition of carbonate, and reducing the preparation difficulty.
[0014] 5、The preparation method of the application is simple, one-step heat treatment can be realized, the overall preparation process time is shortened, the preparation efficiency is improved, and expensive equipment is not required, having a low-cost advantage.
[0015] The technical solutions of the application will be further described in detail through examples. DETAILED DESCRIPTION
[0016] Example 1 The embodiment includes the following steps: Step one, bismuth oxide, strontium carbonate, calcium carbonate and copper oxide are mixed according to the atomic ratio Bi:Sr:Ca:Cu = 2.1:1.9:0.9:2, and then ground to obtain mixture 1#; Step two, the mixture 1# obtained in step one is mixed with sodium carboxymethyl cellulose and water according to the mass ratio 1:0.02:4 and stirred, the stirring speed is 30000 rpm, and the time is 1 min, to obtain mixed slurry 1#; Step three, the mixed slurry 1# obtained in step two is cooled in liquid nitrogen, and freeze-dried under the conditions of vacuum degree 1 Pa and temperature-80 DEG C to obtain porous blank 1#; Step four, the porous blank 1# obtained in step three is heat treated, the highest temperature of heat treatment is 840 DEG C, and the time is 10 h, to obtain Bi-based superconducting powder.
[0017] The Bi-based superconducting powder prepared in the embodiment, i.e. Bi2212 superconducting powder, has a superconducting phase content of 98%, an average width of a sheet layer of about 2 μm, and a sheet layer thickness of about 150 nm, indicating that the Bi-based superconducting powder prepared by the method has a small size, good uniformity and excellent performance.
[0018] Example 2 The embodiment includes the following steps: Step one, bismuth oxide, strontium nitrate, calcium carbonate and copper oxide are mixed according to the atomic ratio Bi:Sr:Ca:Cu = 2.05:1.95:0.95:2, and then ground to obtain a mixture 2#; Step two, the mixture 2# obtained in step one is mixed with ethyl cellulose and ethanol according to a mass ratio of 1:0.3:20 and stirred at a speed of 300 rpm for 5 min to obtain a mixed slurry 2#; Step three, the mixed slurry 1# obtained in step two is cooled in liquid nitrogen and freeze-dried under the conditions of a vacuum degree of 1 Pa and a temperature of -80℃ to obtain a porous blank 2#; Step four, the porous blank 2# obtained in step three is heat treated at a maximum temperature of 860℃ for 1 h to obtain a Bi-based superconducting powder.
[0019] The Bi-based superconducting powder prepared in the embodiment, i.e. Bi2212 superconducting powder, has a superconducting phase content of 98%, an average width of a sheet layer of about 2 μm, and a sheet layer thickness of about 150 nm, indicating that the Bi-based superconducting powder prepared by the method has a small size, good uniformity and excellent performance.
[0020] Example 3 The embodiment includes the following steps: Step one, bismuth oxide, lead nitrate, strontium carbonate, calcium carbonate and copper oxide are mixed according to the atomic ratio Bi:Pb:Sr:Ca:Cu = 1.8:0.3:2:2:3, and then ground to obtain a mixture 3#; Step two, the mixture 3# obtained in step one is mixed with sodium carboxymethyl cellulose and water according to a mass ratio of 1:0.1:10 and stirred at a speed of 15000 rpm for 2 min to obtain a mixed slurry 3#; Step three, the mixed slurry 3# obtained in step two is cooled in liquid nitrogen and freeze-dried under the conditions of a vacuum degree of 1 Pa and a temperature of -80℃ to obtain a porous blank 3#; Step four, the porous blank 3# obtained in step three is heat treated at a maximum temperature of 800℃ for 10 h to obtain a Bi-based superconducting powder.
[0021] The Bi2223 superconducting powder prepared in the embodiment contains 95% superconducting phase, the average width of the sheet layer is about 1.4 μm, and the thickness of the sheet layer is about 100 nm, indicating that the Bi superconducting powder prepared by the method has small size, good uniformity and excellent performance.
[0022] Example 4 The embodiment includes the following steps: Step one, bismuth oxide, lead nitrate, strontium nitrate, calcium carbonate, copper oxide are mixed according to the atomic ratio Bi:Pb:Sr:Ca:Cu =1.8:0.3:2:2:3, and then grinded to obtain a mixture 4#; Step two, the mixture 4# obtained in step one is mixed with ethyl cellulose and tert-butyl alcohol according to the mass ratio 1:0.15:15 and stirred at a speed of 500 rpm for 3 min to obtain a mixed slurry 4#; Step three, the mixed slurry 4# obtained in step two is cooled in liquid nitrogen and freeze-dried under the conditions of a vacuum degree of 1 Pa and a temperature of-80℃ to obtain a porous blank 4#; Step four, the porous blank 4# obtained in step three is heat treated at a maximum temperature of 810℃ for 1 h to obtain a Bi superconducting powder.
[0023] The Bi2223 superconducting powder prepared in the embodiment contains 95% superconducting phase, the average width of the sheet layer is about 1.4 μm, and the thickness of the sheet layer is about 100 nm, indicating that the Bi superconducting powder prepared by the method has small size, good uniformity and excellent performance.
[0024] The above description is only a preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change and equivalent change made according to the technical essence of the present application to the above embodiment are still within the protection scope of the technical solution of the present application.
Claims
1. A method for preparing low-cost Bi-based superconducting powder, characterized in that: The method comprises the following steps: Step 1: Mix bismuth oxide, strontium carbonate, calcium carbonate, and copper oxide according to the atomic ratio of Bi:Sr:Ca:Cu=(2+x):(2-y):(1-y):2, where x=0.05-0.2 and y=0.05-0.15, and then grind to obtain mixture 1#; Alternatively, bismuth oxide, strontium nitrate, calcium carbonate, and copper oxide are mixed in an atomic ratio of Bi:Sr:Ca:Cu=(2+x):(2-y):(1-y):2, where x=0.05-0.2 and y=0.05-0.15, and then ground to obtain a mixture 2#; Alternatively, bismuth oxide, lead nitrate, strontium carbonate, calcium carbonate, and copper oxide are mixed in an atomic ratio of Bi:Pb:Sr:Ca:Cu=1.8:0.3:2:2:3, and then ground to obtain mixture 3#; Alternatively, bismuth oxide, lead nitrate, strontium nitrate, calcium carbonate, and copper oxide are mixed in an atomic ratio of Bi:Pb:Sr:Ca:Cu=1.8:0.3:2:2:3, and then ground to obtain a mixture 4#; Step 2: Mixing and stirring the mixture 1#, mixture 2#, mixture 3# or mixture 4# obtained in step 1 with the polymer and the solvent in a mass ratio of 1:a:b, wherein a=0.02-0.3 and b=4-20, to obtain mixed slurry 1#, mixed slurry 2#, mixed slurry 3# or mixed slurry 4#, respectively; Step 3: freeze-drying the mixed slurry 1#, mixed slurry 2#, mixed slurry 3# or mixed slurry 4# obtained in step 2 to obtain porous blank 1#, porous blank 2#, porous blank 3# or porous blank 4#; Step 4: heat-treating the porous blank 1#, porous blank 2#, porous blank 3# or porous blank 4# obtained in step 3 to obtain Bi-based superconducting powder.
2. The method for preparing a low-cost Bi-based superconducting powder according to claim 1, characterized in that: In step 2, the polymer is sodium carboxymethyl cellulose or ethyl cellulose, the solvent is water, ethanol or tert-butanol, the stirring speed is 300 rpm to 30,000 rpm, and the stirring time is 1 min to 5 min.
3. The method for preparing a low-cost Bi-based superconducting powder according to claim 1, characterized in that: The freeze-drying process in step three is: cooling in liquid nitrogen, and the freeze-drying conditions are vacuum degree 1 Pa and temperature -80°C.
4. The method for preparing a low-cost Bi-based superconducting powder according to claim 1, characterized in that: In step 4, the maximum heat treatment temperature of porous blanks 1# and 2# is 840°C~860°C, and the time is 1h~10h. The maximum heat treatment temperature of porous blanks 3# and 4# is 800°C~810°C, and the time is 1h~10h.