阅读说明：本技术 一种化学燃烧制备Bi2212微纳粉末的方法 (Method for preparing Bi2212 micro-nano powder by chemical combustion ) 是由 金利华 李成山 白利锋 刘国庆 徐晓燕 焦高峰 郝清滨 李珍宝 于 2021-09-08 设计创作，主要内容包括：本发明公开了一种化学燃烧制备Bi2212微纳粉末的方法,该方法包括：一、将Bi2212共沉淀粉末与冰乙酸恒温搅拌反应后与无水乙醇、丙烯酸混合得到前驱液；或者将氧化铋、氧化铜、碳酸钙、碳酸锶混合研磨后热处理,与冰乙酸混合进行恒温搅拌反应后与无水乙醇、丙烯酸混合得到前驱液；二、将前驱液在燃烧腔体内喷出形成雾滴,通入空气并点燃使雾滴燃烧反应得到纳米氧化物粉末；三、成相热处理得到Bi2212微纳粉末。本发明利用前驱液中无水乙醇和丙烯酸的助燃作用,使得前驱液雾滴处于高温状态下并直接气化得到纳米氧化物粉末,解决了传统热分解方法中热解产物颗粒尺寸较大的问题,提高了Bi2212微纳粉末的反应活性和制备效率。(The invention discloses a method for preparing Bi2212 micro-nano powder by chemical combustion, which comprises the following steps: firstly, stirring and reacting Bi2212 coprecipitated starch powder with glacial acetic acid at constant temperature, and then mixing with absolute ethyl alcohol and acrylic acid to obtain a precursor solution; or mixing and grinding bismuth oxide, copper oxide, calcium carbonate and strontium carbonate, then carrying out heat treatment, mixing with glacial acetic acid, carrying out constant-temperature stirring reaction, and then mixing with absolute ethyl alcohol and acrylic acid to obtain a precursor solution; secondly, spraying the precursor liquid in a combustion cavity to form fog drops, introducing air and igniting to enable the fog drops to be subjected to combustion reaction to obtain nano oxide powder; and thirdly, performing phase forming heat treatment to obtain Bi2212 micro-nano powder. According to the invention, the combustion supporting effect of absolute ethyl alcohol and acrylic acid in the precursor liquid is utilized, so that the precursor liquid fog drops are in a high-temperature state and are directly gasified to obtain the nano oxide powder, the problem that the particle size of a pyrolysis product in the traditional thermal decomposition method is large is solved, and the reactivity and the preparation efficiency of the Bi2212 micro-nano powder are improved.)

1. A method for preparing Bi2212 micro-nano powder by chemical combustion is characterized by comprising the following steps:

step one, preparing a precursor solution: mixing the Bi2212 co-precipitated powder with glacial acetic acid, stirring at constant temperature for reaction to obtain a clear acetate solution, and then mixing the acetate solution with absolute ethyl alcohol and acrylic acid to obtain a stable and clear precursor solution;

or mixing bismuth oxide, strontium carbonate, calcium carbonate and copper oxide according to the ratio of Bi: sr: ca: mixing Cu in an atomic ratio of 1.05:1.9:0.86:2.0 to form mixed powder, grinding for 30min, then putting into a burning boat, placing into a muffle furnace to react at a constant temperature of 800 ℃ for 2h to carry out heat treatment, then mixing the mixed powder after heat treatment with glacial acetic acid, carrying out constant-temperature stirring reaction to obtain clear acetate solution, and then mixing the acetate solution with absolute ethyl alcohol and acrylic acid to obtain stable and clear precursor solution;

step two, preparing nano oxide powder: filling the precursor liquid obtained in the step one into a storage tank (1), injecting the precursor liquid into an inner pipe of a spray pipe (4) through a liquid guide pipe (7) under the action of a diaphragm pump (3), spraying the precursor liquid into a combustion cavity (5) to form fog drops, then injecting air into an outer pipe of the spray pipe (4) through an air guide pipe (6) by adopting an air compressor (2) and enabling the air to enter the combustion cavity (5), and igniting the air to enable the fog drops to perform combustion reaction to obtain nano oxide powder;

step three, preparing Bi2212 micro-nano powder: and (4) carrying out phase forming heat treatment on the nano oxide powder obtained in the step two to obtain Bi2212 micro-nano powder.

2. The method for preparing Bi2212 micro-nano powder by chemical combustion as claimed in claim 1, wherein in the first step, the ratio of each metal element in the Bi2212 co-deposited powder is Bi: sr: ca: 2.17% of Cu: 1.94: 0.89: 2; the temperature of heat treatment in the preparation process of the Bi2212 coprecipitation powder is 500-850 ℃; the temperature of the constant-temperature stirring reaction of the Bi2212 coprecipitation powder and the glacial acetic acid and the constant-temperature stirring reaction of the mixed powder after the heat treatment and the glacial acetic acid are both 80-120 ℃, and the stirring speed is both 200-300 r/min.

3. The method for preparing Bi2212 micro-nano powder by chemical combustion as claimed in claim 1, wherein in the first step, the mass ratio of the Bi2212 co-precipitated powder to glacial acetic acid is 1:5, and the volume ratio of the acetate solution to absolute ethyl alcohol and acrylic acid is 1: 3-6: 0.5 to 1.

4. The method for preparing Bi2212 micro-nano powder by chemical combustion as claimed in claim 1, wherein the mass ratio of the mixed powder after the heat treatment to the glacial acetic acid in the step one is 1:6, and the volume ratio of the corresponding acetate solution to the absolute ethyl alcohol and the acrylic acid is 1: 3-6: 0.5 to 1.

5. The method for preparing Bi2212 micro-nano powder by chemical combustion according to claim 1, characterized in that the flow rate of the precursor liquid in the second step is 1L/h-2L/h under the action of a diaphragm pump (3); the flow rate of the air under the action of the air compressor (2) is 60L/min.

6. The method for preparing Bi2212 micro-nano powder by chemical combustion as claimed in claim 1, wherein the atmosphere used in the phase forming heat treatment in step three is air or oxygen, the temperature used is 860 ℃ and the time is 5 h-20 h.

7. The method for preparing Bi2212 micro-nano powder by chemical combustion as claimed in claim 1, wherein in the third step, the Bi2212 micro-nano powder contains lamellar Bi2212 powder, the thickness of the lamellar is less than 200nm, and the average width of the lamellar diameter is not more than 1 μm.

Technical Field

The invention belongs to the technical field of high-temperature superconducting materials, and particularly relates to a method for preparing Bi2212 micro-nano powder by chemical combustion.

Background

Bi₂Sr₂CaCu₂O_xThe (Bi-2212) wire has excellent low-temperature high-field current-carrying performance and is a research hotspot of the current high-temperature superconducting material. The precursor powder with high quality is a precondition for obtaining the Bi-2212 wire with high performance. The improvement or optimization of the preparation technology of the precursor powder is the key core of the research field of the Bi-2212 wire. In order to improve the quality and uniformity of the precursor powder, researchers prepared the Bi2212 precursor powder by different methods. For example, oxide powders of bismuth, strontium, calcium and copper are melted at high temperature by a fusion casting method to obtain a bulk material containing a mesophase, the bulk material is further crushed, jet-ground and briquetted, and then the mesophase is converted into a high-purity Bi-2212 phase by a multi-step sintering heat treatment under air conditions. Or mixing a nitrate water solution and an oxalic acid ethanol solution by adopting a coprecipitation method to form an oxalate mixture, reducing ion residues in a supernatant by accurately controlling the pH value, the aging temperature and the time of the mixture to obtain an oxalate precipitate with a good stoichiometric ratio, and carrying out heat treatment such as multi-step grinding, pyrolysis, sintering and the like to obtain the Bi-2212 precursor powder. The methods generally require more process steps, have longer powder preparation period and are sintered in multiple steps; meanwhile, the powder obtained by the traditional method has larger size and poor uniformity, and the precursor powder has low quality, so that the wire rod performance is low.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for preparing Bi2212 micro-nano powder by chemical combustion aiming at the defects of the prior art. According to the method, absolute ethyl alcohol and acrylic acid are added into an acetate precursor to be mixed into a precursor solution for combustion reaction, and the combustion supporting effect of the absolute ethyl alcohol and the acrylic acid in the precursor solution is utilized to enable the precursor solution fog drops to be in a high-temperature state and directly gasified to obtain the nano oxide powder, so that the problem that the size of pyrolysis product particles is large due to the fact that fog drops shrink and agglomerate when heated in the traditional thermal decomposition method is solved, the uniformity of the nano oxide powder is high, segregation does not exist among the particles and does not agglomerate, and the quality of the Bi2212 micro-nano powder is improved.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for preparing Bi2212 micro-nano powder by chemical combustion is characterized by comprising the following steps:

step one, preparing a precursor solution: mixing the Bi2212 co-precipitated powder with glacial acetic acid, stirring at constant temperature for reaction to obtain a clear acetate solution, and then mixing the acetate solution with absolute ethyl alcohol and acrylic acid to obtain a stable and clear precursor solution;

or mixing bismuth oxide, strontium carbonate, calcium carbonate and copper oxide according to the ratio of Bi: sr: ca: mixing Cu in an atomic ratio of 1.05:1.9:0.86:2.0 to form mixed powder, grinding for 30min, then putting into a burning boat, placing into a muffle furnace to react at a constant temperature of 800 ℃ for 2h to carry out heat treatment, then mixing the mixed powder after heat treatment with glacial acetic acid, carrying out constant-temperature stirring reaction to obtain clear acetate solution, and then mixing the acetate solution with absolute ethyl alcohol and acrylic acid to obtain stable and clear precursor solution;

step two, preparing nano oxide powder: filling the precursor liquid obtained in the step one into a storage tank, injecting the precursor liquid into an inner pipe of a spray pipe through a liquid guide pipe under the action of a diaphragm pump, spraying the precursor liquid into a combustion cavity to form fog drops, then injecting air into an outer pipe of the spray pipe through a gas guide pipe by using an air compressor, entering the outer pipe into the combustion cavity, and igniting the air to enable the fog drops to perform combustion reaction to obtain nano oxide powder;

step three, preparing Bi2212 micro-nano powder: and (4) carrying out phase forming heat treatment on the nano oxide powder obtained in the step two to obtain Bi2212 micro-nano powder.

The invention obtains acetate precursor by reacting Bi2212 coprecipitation powder with glacial acetic acid, or obtains acetate precursor by reacting each raw material powder with glacial acetic acid after direct grinding and heat treatment, then mixes the acetate precursor with absolute ethyl alcohol and acrylic acid to form precursor liquid, improves the stability of the components of the precursor liquid by chelating metal ions in the precursor liquid with the acrylic acid, sends the precursor liquid into a combustion chamber body, introduces air and ignites the precursor liquid to carry out combustion reaction, under the direct combustion supporting effect of the absolute ethyl alcohol and the acrylic acid in the precursor liquid, the precursor liquid fog drops are in a high temperature state and are directly gasified to obtain nano-sized and multi-component nano-oxide powder, thereby solving the problem that the fog drops are heated, shrunk and agglomerated to cause the particle size of a pyrolysis product to be larger in the traditional thermal decomposition method, and the nano-oxide powder has high uniformity, no segregation among particles, no agglomeration and high reaction activity, the method is beneficial to the subsequent low-temperature and rapid phase formation of Bi2212 powder to obtain the Bi2212 micro-nano powder, and further is beneficial to the improvement of the performance of the subsequent Bi2212 wire.

The method for preparing the Bi2212 micro-nano powder by chemical combustion is characterized in that in the first step, the proportion of each metal element in the Bi2212 co-precipitated powder is Bi: sr: ca: 2.17% of Cu: 1.94: 0.89: 2; the temperature of heat treatment in the preparation process of the Bi2212 coprecipitation powder is 500-850 ℃; the temperature of the constant-temperature stirring reaction of the Bi2212 coprecipitation powder and the glacial acetic acid and the constant-temperature stirring reaction of the mixed powder after the heat treatment and the glacial acetic acid are both 80-120 ℃, and the stirring speed is both 200-300 r/min.

The method for preparing the Bi2212 micro-nano powder by chemical combustion is characterized in that in the first step, the mass ratio of the Bi2212 co-precipitated powder to the glacial acetic acid is 1:5, and the volume ratio of the corresponding acetate solution to the absolute ethyl alcohol and the acrylic acid is 1: 3-6: 0.5 to 1.

The method for preparing the Bi2212 micro-nano powder by chemical combustion is characterized in that the mass ratio of the mixed powder subjected to the heat treatment to glacial acetic acid in the step one is 1:6, and the volume ratio of the corresponding acetate solution to absolute ethyl alcohol to acrylic acid is 1: 3-6: 0.5 to 1.

The method for preparing the Bi2212 micro-nano powder by chemical combustion is characterized in that the flow rate of the precursor liquid under the action of the diaphragm pump in the second step is 1L/h-2L/h; the flow rate of the air under the action of the air compressor is 60L/min.

The method for preparing the Bi2212 micro-nano powder by chemical combustion is characterized in that the atmosphere adopted by the phase forming heat treatment in the step three is air or oxygen, the adopted temperature is 860 ℃, and the time is 5-20 hours.

The method for preparing the Bi2212 micro-nano powder by chemical combustion is characterized in that the Bi2212 micro-nano powder in the third step contains lamellar Bi2212 powder, the thickness of the lamellar is less than 200nm, and the average width is not more than 1 mu m.

Compared with the prior art, the invention has the following advantages:

1. according to the invention, absolute ethyl alcohol and acrylic acid are added into an acetate precursor to be mixed into a precursor solution for combustion reaction, and the combustion supporting effect of the absolute ethyl alcohol and the acrylic acid in the precursor solution is utilized to enable the precursor solution fog drops to be in a high-temperature state and to be directly gasified to obtain the nano oxide powder, so that the problem that the fog drops are heated, shrunk and agglomerated to cause larger particle size of pyrolysis products in the traditional thermal decomposition method is solved, the uniformity of the nano oxide powder is high, segregation among particles is not existed, agglomeration is not caused, the quality of the Bi2212 micro-nano powder is improved, the time of the whole combustion powder preparation process is short, and the rapid preparation of the Bi2212 micro-nano powder is realized.

2. The nano oxide powder obtained by the method has high reaction activity and short interatomic diffusion distance, the multi-component nano particles begin to be converted into Bi2212 crystal grains at a low temperature stage, one-step heat treatment phase reaction is realized, and compared with the traditional multi-step sintering heat treatment, the Bi2212 micro-nano powder has high phase reaction rate, and the comprehensive preparation efficiency is improved.

3. According to the invention, the quality of the Bi2212 micro-nano powder is improved by controlling the quality of the nano oxide powder, the Bi2212 micro-nano powder obtained by phase formation has high-purity phase composition and size uniformity, the thickness of the Bi2212 micro-nano powder sheet layer is less than 200nm, the average width is not more than 1 mu m, the melting consistency of the Bi2212 wire core wire used for preparing the Bi2212 wire rod subsequently is improved, the recrystallization growth of Bi2212 crystal grains is promoted, the orientation and the connection performance of the crystal grains are improved, and the superconducting performance of the Bi2212 wire rod is further improved.

4. The preparation method of the invention has the advantages of simplicity, short flow, high efficiency and easy realization of industrialization

The technical solution of the present invention is further described in detail by the accompanying drawings and examples.

Drawings

Fig. 1 is a schematic structural diagram of a chemical combustion device adopted for preparing Bi2212 micro-nano powder.

Description of reference numerals:

1, a material storage tank; 2, an air compressor; 3, a diaphragm pump;

4, spraying a pipe; 5, a combustion cavity; 6, a gas guide tube;

7-a catheter.

Detailed Description

As shown in fig. 1, the chemical combustion device for preparing the Bi2212 micro-nano powder comprises a combustion cavity 5 and a spray pipe 4 connected to the combustion cavity 5, wherein the spray pipe 4 is composed of an inner pipe and an outer pipe which are sleeved in a ring, the inner pipe of the spray pipe 4 is connected with a material storage tank 1 through a liquid guide pipe 7, a diaphragm pump 3 is arranged on the liquid guide pipe 7, and the outer pipe of the spray pipe 4 is connected with an air compressor 2 through an air guide pipe 6.

Example 1

The embodiment comprises the following steps:

step one, preparing a precursor solution: mixing Bi2212 coprecipitated powder and glacial acetic acid according to the mass ratio of 1:5, carrying out constant-temperature stirring reaction at the temperature of 120 ℃ and the stirring speed of 200r/min to obtain a clear acetate solution, and then mixing the acetate solution with absolute ethyl alcohol and acrylic acid according to the mass ratio of 1: 6: 1 to obtain stable and clear precursor liquid; the proportion of each metal element in the Bi2212 coprecipitation powder is Bi: sr: ca: 2.17% of Cu: 1.94: 0.89: 2, the temperature of heat treatment in the preparation process of the Bi2212 coprecipitation powder is 850 ℃;

step two, preparing nano oxide powder: filling the precursor liquid obtained in the step one into a storage tank 1, injecting the precursor liquid into an inner pipe of a spray pipe 4 through a liquid guide pipe 7 at a flow rate of 1L/h under the action of a diaphragm pump 3, spraying the precursor liquid into a combustion cavity 5 to form fog drops, then injecting air into an outer pipe of the spray pipe 4 through an air guide pipe 6 at a flow rate of 60L/min by using an air compressor 2, and entering the combustion cavity 5, and igniting the air to enable the fog drops to perform combustion reaction to obtain nano oxide powder;

step three, preparing Bi2212 micro-nano powder: carrying out phase forming heat treatment on the nano oxide powder obtained in the step two to obtain Bi2212 micro-nano powder; the atmosphere adopted by the phase forming heat treatment is air, the adopted temperature is 860 ℃, and the time is 20 hours.

Through detection, the size of the nano oxide powder prepared by the embodiment is 20nm, the components are uniform, after the phase forming heat treatment, the obtained Bi2212 micro-nano powder contains lamellar Bi2212 powder, the thickness of the lamellar layer is less than 200nm, the average width is 1 mu m, and the Bi2212 phase content in the Bi2212 micro-nano powder reaches 99.5%.

Example 2

The embodiment comprises the following steps:

step one, preparing a precursor solution: mixing bismuth oxide, strontium carbonate, calcium carbonate and copper oxide according to the proportion of Bi: sr: ca: mixing Cu at an atomic ratio of 1.05:1.9:0.86:2.0 to form mixed powder, grinding for 30min, putting into a burning boat, placing in a muffle furnace, reacting at a constant temperature of 800 ℃ for 2h for heat treatment, mixing the heat-treated mixed powder with glacial acetic acid according to a mass ratio of 1:6, stirring at a constant temperature of 80 ℃ and a stirring speed of 300r/min for reaction to obtain clear acetate solution, and mixing the acetate solution with absolute ethyl alcohol and acrylic acid according to a ratio of 1: 6: 1 to obtain stable and clear precursor liquid;

step two, preparing nano oxide powder: filling the precursor liquid obtained in the step one into a storage tank 1, injecting the precursor liquid into an inner pipe of a spray pipe 4 through a liquid guide pipe 7 at a flow rate of 1L/h under the action of a diaphragm pump 3, spraying the precursor liquid into a combustion cavity 5 to form fog drops, then injecting air into an outer pipe of the spray pipe 4 through an air guide pipe 6 at a flow rate of 60L/min by using an air compressor 2, and entering the combustion cavity 5, and igniting the air to enable the fog drops to perform combustion reaction to obtain nano oxide powder;

step three, preparing Bi2212 micro-nano powder: carrying out phase forming heat treatment on the nano oxide powder obtained in the step two to obtain Bi2212 micro-nano powder; the atmosphere adopted by the phase forming heat treatment is oxygen, the adopted temperature is 860 ℃, and the time is 20 hours.

Through detection, the size of the nano oxide powder prepared by the embodiment is 50nm, the components are uniform, after the phase forming heat treatment, the obtained Bi2212 micro-nano powder contains lamellar Bi2212 powder, the thickness of the lamellar layer is less than 200nm, the average width is 1 mu m, and the Bi2212 phase content in the Bi2212 micro-nano powder is up to 99.5%.

Example 3

The embodiment comprises the following steps:

step one, preparing a precursor solution: mixing Bi2212 coprecipitated powder and glacial acetic acid according to the mass ratio of 1:5, carrying out constant-temperature stirring reaction at the temperature of 120 ℃ and the stirring speed of 200r/min to obtain a clear acetate solution, and then mixing the acetate solution with absolute ethyl alcohol and acrylic acid according to the mass ratio of 1: 3: mixing at a volume ratio of 0.5 to obtain a stable and clear precursor solution; the proportion of each metal element in the Bi2212 coprecipitation powder is Bi: sr: ca: 2.17% of Cu: 1.94: 0.89: 2, the temperature of heat treatment in the preparation process of the Bi2212 coprecipitation powder is 500 ℃;

step two, preparing nano oxide powder: filling the precursor liquid obtained in the step one into a storage tank 1, injecting the precursor liquid into an inner pipe of a spray pipe 4 through a liquid guide pipe 7 at a flow rate of 2L/h under the action of a diaphragm pump 3, spraying the precursor liquid into a combustion cavity 5 to form fog drops, then injecting air into an outer pipe of the spray pipe 4 through an air guide pipe 6 at a flow rate of 60L/min by using an air compressor 2, and entering the combustion cavity 5, and igniting the air to enable the fog drops to perform combustion reaction to obtain nano oxide powder;

step three, preparing Bi2212 micro-nano powder: carrying out phase forming heat treatment on the nano oxide powder obtained in the step two to obtain Bi2212 micro-nano powder; the atmosphere adopted by the phase forming heat treatment is air, the adopted temperature is 860 ℃, and the time is 5 hours.

Through detection, the size of the nano oxide powder prepared by the embodiment is 70nm, the components are uniform, after the phase forming heat treatment, the obtained Bi2212 micro-nano powder contains lamellar Bi2212 powder, the thickness of the lamellar layer is less than 200nm, the average width is 1 mu m, and the Bi2212 phase content in the Bi2212 micro-nano powder reaches 99%.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent changes of the above embodiments according to the technical essence of the invention are still within the protection scope of the technical solution of the invention.