Beta ''-aluminum oxide formula and production process

Abstract

The invention relates to a beta ''-aluminum oxide formula and a production process, and the method comprises the following steps: uniformly mixing an aluminum source and a sodium source to obtain mixed raw material powder; carrying out wet ball milling on the mixed raw material powder by taking deionized water as a ball milling medium, and then drying to obtain uniformly dried beta ''-aluminum oxide precursor powder; and finally, calcining the dried precursor powder at a high temperature (950-1650 DEG C) for 2-4 hours in stages to obtain the beta ''-aluminum oxide powder with good fluidity, high sphericity and uniform particle size distribution.

Description

Technical Field

[0001] The invention relates to a β″-alumina formula and a production process, belonging to the technical field of new materials. Background Art

[0002] Al 2 O 3 It is a widely used chemical raw material. Currently, it is known to have twelve crystal forms, including α, β, and γ. Among them, β″-alumina has become an indispensable ceramic electrolyte material in high-performance energy storage devices such as sodium-sulfur batteries due to its unique crystal structure and excellent physical and chemical properties, especially stability and conductivity at high temperatures. In addition, β″-alumina materials are also widely used in sodium-nickel batteries (ZEBRA), alkali metal thermoelectric converters and other fields.

[0003] In the prior art, a one-stage calcination method is mostly used in the preparation of β″-alumina, which results in limited decomposition of the material calcined at a single temperature. In addition, patent CN105502449A discloses a β″-alumina formula and production process in the field of inorganic materials. In the wet ball milling of this method, the ball milling medium is alcohol, and the production process needs to be produced under nitrogen protection, so this technology inevitably has the problem of potential safety hazards. In addition, although alcohol has good wettability on the mixture, it is easy to absorb water, and the specific gravity does not meet the standard after a period of time. The traditional process for the preparation of β″-alumina has problems such as high energy consumption, complex process, unstable product purity and performance, which limits its large-scale industrial application. Therefore, there is an urgent need for a β″-alumina formula and production process with a short process flow, low energy consumption and stable product performance. Summary of the invention

[0004] In view of the above problems, the present invention adopts deionized water as the wet ball milling medium, and the calcination process adopts a staged calcination method. The present invention aims to provide a β″-alumina formula and production process with a short process flow, low energy consumption, and stable product performance, eliminating potential safety hazards and eliminating the need for fire and explosion prevention. The β″-alumina produced by the present invention has the characteristics of stability, uniform particles, and good molding.

[0005] The specific plan is:

[0006] (1) uniformly mixing an aluminum source and a sodium source to obtain a mixed raw material powder;

[0007] (2) using deionized water as a ball milling medium and adding an appropriate amount of a dispersant to wet-mill the mixed raw material powder to obtain a uniform and stable slurry;

[0008] (3) Add 2% by weight of a natural rubber binder to the slurry obtained in step (2), and stir for 2 to 3 hours to mix evenly.

[0009] (3) then drying the obtained slurry by a spray dryer to obtain a dry and uniform β″-alumina precursor powder;

[0010] (4) Finally, the dried precursor powder is calcined at high temperature under argon protection. The first stage of high temperature calcination is at 950-1100°C for 0.5-1h. The second stage of high temperature calcination is at 1100-1300°C for 1-1.5h. The third stage of high temperature calcination is at 1300-1650°C for 1-1.5h. β″-alumina powder is obtained.

[0011] Preferably, the Al 2 O 3 The aluminum source includes one or a combination of the following: Al 2 O 3 、Al 2 O 3 ·3H2O、Al(OH) 3 , α-alumina.

[0012] Preferably, the Na 2 The sodium source of O includes one of the following: Na 2 CO 3 、Na 2 SO 4 .

[0013] Preferably, the aluminum source is 75% α-alumina and 25% Al(OH) 3 The composite aluminum source is obtained by compounding in proportion.

[0014] Preferably, the sodium source is 15% Na 2 CO 3 and 85% Na 2 SO 4 The composite sodium source is obtained by compounding in proportion.

[0015] Preferably, the β″-alumina precursor powder is composed of 24% to 25% of a composite sodium source and 75% to 76% of a composite aluminum source.

[0016] Preferably, 1% to 2% by mass of LiOH is added to the β″-alumina precursor powder as a lithium source.

[0017] Preferably, the wet ball milling dispersant is glycerol or polyacrylamide.

[0018] Preferably, the spray drying parameters are set as follows: the hot air inlet temperature is controlled at 100-250°C, the outlet temperature is 80-150°C, and the atomizing disk speed is 8000-12500r / min.

[0019] Preferably, the calcination process parameters include: calcination temperature of 950-1650°C, calcination time of 2 to 4 hours, total pressure in the furnace controlled at 150 to 200 KPa, argon protection is introduced during the calcination process, and the argon flow rate is maintained at 100 mL / min.

[0020] The advantage of the present invention is that through specific raw material selection and ratio, combined with innovative ball milling and calcination processes, and staged calcination, efficient preparation of β″-alumina powder is achieved. This method not only simplifies the traditional preparation process, but also significantly improves the purity and uniformity of the product, providing strong support for the application of β″-alumina in high-end fields. The process of the present invention is safe, environmentally friendly, simple, low in energy consumption, high in product purity, and stable in performance. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention rather than to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed according to general international standards, conventional conditions, or are carried out.

[0022] 1.Raw materials

[0023] Aluminum source: The aluminum source is 75% α-alumina and 25% Al(OH) 3 The composite aluminum source is obtained by compounding in proportion.

[0024] Sodium source: Sodium source uses 15% Na 2 CO 3 and 85% Na 2 SO 4 The composite sodium source is obtained by compounding in a certain proportion. Because the reaction conditions with alumina or aluminum hydroxide are mild, it is easy to control the formation of β″-alumina.

[0025] 2. Preparation process

[0026] Raw material mixing: The aluminum source and the sodium source weighed in proportion are mixed evenly to obtain a mixed raw material powder.

[0027] Wet ball milling: Use deionized water as the ball milling medium, add an appropriate amount of dispersant (such as polyacrylamide, glycerol), and wet ball mill the mixed raw material powder to obtain a uniform and stable slurry.

[0028] Spray drying: The wet ball-milled slurry is dried by a spray dryer. The hot air inlet temperature is controlled at 100-250°C, the outlet temperature is 80-150°C, and the atomizing disk speed is 8000-12500r / min, so that the water in the slurry evaporates quickly to obtain dry and uniform β″-alumina precursor powder.

[0029] Calcination: The dried precursor powder is calcined in stages at high temperature (such as 950-1650°C) for 2-4 hours, the first stage of high temperature calcination temperature is 950-1100°C, calcination temperature is 0.5-1h; the second stage of high temperature calcination temperature is 1100-1300°C, calcination temperature is 1-1.5h; the third stage of high temperature calcination temperature is 1300-1650°C, calcination temperature is 1-1.5h; solid phase reaction occurs, and cooling is performed to obtain β″-alumina powder.

[0030] Example 1

[0031] 24.06 parts of composite sodium source and 75.94 parts of composite aluminum source were used as raw materials for mixing and obtaining raw material powder. Deionized water was used as the ball milling medium, and an appropriate amount of polyacrylamide was added to wet-mill the mixed raw material powder for 24 hours to obtain a uniform and stable slurry. Then, under the conditions of hot air inlet temperature of 250°C, hot air outlet temperature of 150°C, and atomizing disk speed of 12500r / min, the water in the slurry was evaporated to obtain a dry and uniformly mixed β"-alumina precursor powder. The dried precursor powder was calcined in stages at high temperature for 4 hours to produce a solid phase reaction to generate β"-alumina powder.

[0032] Example 2

[0033] 24.06 parts of composite sodium source and 75.94 parts of composite aluminum source are used as raw materials for mixing and obtaining raw material powder. Deionized water is used as the ball milling medium, and an appropriate amount of glycerol is added to wet-mill the mixed raw material powder for 24 hours to obtain a uniform and stable slurry. Then, under the conditions of a hot air inlet temperature of 200°C, a hot air outlet temperature of 80°C, and an atomizing disk speed of 12000r / min, the water in the slurry is evaporated to obtain a dry and uniformly mixed β″-alumina precursor powder. The dried precursor powder is calcined in stages at high temperature for 4 hours to produce a solid-phase reaction to generate β″-alumina powder.

[0034] Example 3

[0035] 24.06 parts of composite sodium source and 75.94 parts of composite aluminum source are used as raw materials and mixed evenly to obtain raw material powder. Deionized water is used as the ball milling medium, and an appropriate amount of polyacrylamide is added to wet-mill the mixed raw material powder for 24 hours to obtain a uniform and stable slurry. Then, under the conditions of a hot air inlet temperature of 250°C, a hot air outlet temperature of 150°C, and an atomizing disk speed of 12500r / min, the moisture in the slurry is evaporated to obtain a dry and uniformly mixed β″-alumina precursor powder. The dried precursor powder is calcined in stages at high temperature for 4 hours to produce a solid-phase reaction to generate β″-alumina powder.

[0036] Example 4

[0037] 24.06 parts of composite sodium source and 75.94 parts of composite aluminum source are used as raw materials for mixing and obtaining raw material powder. Deionized water is used as the ball milling medium, and an appropriate amount of polyacrylamide is added to wet-mill the mixed raw material powder for 24 hours to obtain a uniform and stable slurry. Then, under the conditions of a hot air inlet temperature of 250°C, a hot air outlet temperature of 150°C, and an atomizing disk speed of 12000r / min, the water in the slurry is evaporated to obtain a dry and uniformly mixed β"-alumina precursor powder. The dried precursor powder is calcined in stages at high temperature for 2 hours to produce a solid phase reaction to generate β"-alumina powder.

[0038] The particle size, β" content, specific surface area and thermal conductivity of the β"-alumina powder obtained in Examples 1 to 4 were tested, and ordinary β"-alumina powder purchased from the market was used as a comparative example. The results are shown in Table 1.

[0039] Table 1

[0040] Example 1 Example 2 Example 3 Example 4 Comparative Example <![CDATA[Particle size D 50 / μm]]> 1±0.3 1±0.3 1.2±0.3 1.2±0.3 0.8+0.5 β″ content% 95 96 96 95 86 Specific surface area 0.3 0.3 0.3 0.3 0.6 Thermal conductivity 3.5 3.4 3.5 3.5 2.9

[0041] It can be seen from Table 1 that the β″-alumina powder prepared by the method of the present invention has good sphericity, good particle size uniformity, and uniform particle size distribution.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A β″-alumina formula and production process, characterized in that: The method comprises: (1) uniformly mixing the composite aluminum source and the composite sodium source to obtain a mixed raw material powder; (2) using deionized water as a ball milling medium and adding an appropriate amount of dispersant to wet-mill the mixed raw material powder to obtain a uniform and stable slurry; (3) adding 2% by weight of a natural rubber binder to the slurry obtained in step (2), stirring for 2 to 3 hours, and mixing evenly; (3) then drying the obtained slurry by a spray dryer to obtain dry and uniform β″-alumina precursor powder; (4) Finally, the dried precursor powder is calcined at high temperature under argon protection under controlled total pressure in the furnace. The first stage of high temperature calcination is at 950-1100°C for 0.5-1h. The second stage of high temperature calcination is at 1100-1300°C for 1-1.5h. The third stage of high temperature calcination is at 1300-1650°C for 1-1.5h to finally obtain β″-alumina powder.

2. The method according to claim 1, characterized in that The aluminum source of Al2O3 includes one or a combination of the following: Al2O3, Al2O3·3H2O, Al(OH)3, and α-alumina.

3. The method according to claim 1, characterized in that The sodium source of Na2O includes the following: Na2CO3, Na2SO4.

4. The method according to claim 2, characterized in that: The aluminum source is prepared by compounding 75% α-alumina and 25% Al(OH)3 to obtain a composite aluminum source. The sodium source is prepared by compounding 15% Na2CO3 and 85% Na2SO4 to obtain a composite sodium source.

5. The method according to claims 2 to 4, characterized in that The β″-alumina precursor powder is composed of 10% to 12% of a composite sodium source and 88% to 90% of a composite aluminum source.

6. The method according to claim 1, characterized in that Add 1% to 2% by mass of LiOH as a lithium source to the β″-alumina precursor powder.

7. The method according to claim 1, characterized in that The wet ball milling dispersant is one of glycerol and polyacrylamide, and the added amount of the dispersant accounts for 1% of the mass of the raw material.

8. The method according to claim 1, characterized in that The parameters of the spray drying agent are set as follows: the hot air inlet temperature is controlled at 100-250°C, the outlet temperature is 80-150°C, and the atomizing disk speed is 8000-12500r / min.

9. The method according to claim 1, characterized in that: The process parameters of the calcination include: The calcination temperature is 950-1650°C, the calcination time is 2-4 hours, the total pressure in the furnace is controlled at 150-200 KPa, and argon gas is introduced for protection during the calcination process, and the flow rate of argon gas is maintained at 100 mL / min.