Method for synthesizing alpha-aluminum oxide nano-particles at low temperature, alpha-aluminum oxide nano-particles and application of alpha-aluminum oxide nano-particles

Abstract

The invention discloses a method for synthesizing alpha-aluminum oxide nanoparticles at low temperature. Ammonium aluminum sulfate is used as an aluminum source, ammonium bicarbonate is used as a precipitator, a precipitation product is subjected to acidification treatment, high temperature, high pressure and additional additives are not needed, and the alpha-aluminum oxide nano powder is obtained through roasting at the temperature lower than 1000 DEG C. Furthermore, the alpha-alumina seed crystal is introduced into the acidized precursor, the roasting temperature can be further reduced, and the product is the sphere-like alpha-alumina nano-particles. The aluminum oxide dispersion liquid obtained by dispersing the alpha-aluminum oxide nanoparticles can be applied to the fields of chemical mechanical polishing of integrated circuits, coating of lithium battery diaphragms and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical mechanical polishing, in particular to a method for synthesizing α-alumina nanoparticles at low temperature, α-alumina nanoparticles and uses thereof. BACKGROUND

[0002] There are more than a dozen different crystal phases of alumina, among which α-alumina is a thermodynamically stable phase, and has high chemical stability, a Mohs hardness of 9, and excellent electrical insulation, and is widely used in the fields of semiconductor polishing abrasive, lithium battery separator coating material, surface protection material, optical material, refractory material, etc.

[0003] The synthesis of α-alumina usually requires high-temperature calcination of up to 1200℃ or more, or synthesis in a specially designed high-temperature high-pressure reactor. The phase transition temperature of α-alumina can be effectively reduced by adding seeds or mineralizers, but the additional additives usually introduce impurities, and the addition of fluorides can cause environmental damage. Chinese Patent Publication No. CN 111410220A uses aluminum ammonium sulfate and ammonium bicarbonate as raw materials, and obtains α-alumina nanoparticles by calcining at about 800℃ with the assistance of seeds. The α-alumina particles obtained by this method are small and uniform in size, and the calcination temperature is relatively low, but the precursor needs to be pre-treated by hydrothermal reaction at 160-200℃, and a dispersing agent is added during the hydrothermal process. Chinese Patent Publication No. CN105417562A uses inorganic aluminum source and ammonia water as raw materials, and obtains α-alumina nanopowder by hydrothermal treatment of the precipitate at 100-220℃, followed by calcination at 800-1150℃. This method reduces the calcination temperature to some extent, but also requires hydrothermal treatment of the precursor. Chinese Patent Publication No. CN 105984891 A discloses a method for synthesizing α-alumina nanoparticles at a calcination temperature of 1000℃. This method does not require hydrothermal treatment, and the calcination temperature is reduced, but the precursor is obtained by hydrolysis of expensive organic aluminum source, and a dispersing agent is additionally added. SUMMARY

[0004] In order to overcome the above technical defects, the purpose of the present application is to provide a method for synthesizing α-alumina nanoparticles, comprising: S1) dissolving aluminum ammonium sulfate and ammonium bicarbonate in water respectively, after stirring and dissolving each, mixing the two solutions to obtain a mixed solution with a certain concentration ratio, the mixed solution is reacted at a first temperature T1 for a first time t1 to obtain a precursor 1, the precursor 1 is washed with water and then dried;

[0005] S2) crushing the dried precursor 1, mixing with nitric acid at a certain mass ratio and stirring, and preparing a precursor 2 at a second temperature T2 for a second time t2;

[0006] S3) drying and crushing the precursor 2, and then calcining the precursor 2 in a muffle furnace at a third temperature T3 for a third time t3, and then naturally cooling to obtain the alpha-alumina powder.

[0007] Further, in S1, the molar concentration ratio of the aluminum ammonium sulfate to the ammonium bicarbonate is 1:3.0-1:6.0.

[0008] Further, in S1, T1 is 50-90℃; t1 is 2-8h.

[0009] Further, in S1, after the precursor 1 is washed with water, the precursor 1 is dried in an oven at 80℃ for 12-15h.

[0010] Further, in S2, the mass ratio of the precursor 1 to the nitric acid (calculated based on the concentration of commercially available concentrated nitric acid, 68%) is 1:0.03-1:2, and the preferred ratio is 1:0.2-1:0.9.

[0011] Further, in S2, T2 is 40-90℃; t2 is 2-8h.

[0012] Further, in S3, T3 is 880-980℃; t3 is 4-10h.

[0013] Further, S2 further comprises: S2') mixing alpha-alumina seeds into the precursor 2, controlling the mass ratio of the seeds to the aluminum ammonium sulfate, and then drying and crushing the mixture.

[0014] Further, the mass ratio of the seeds to the aluminum ammonium sulfate is 0.1wt.%-5.6wt.%; and the preferred ratio is 0.34wt.%-3.94wt.%.

[0015] Further, in S3, the heating rate of the muffle furnace is 5-10℃ / min.

[0016] The application also discloses an alpha-alumina nanoparticle synthesized by the synthetic method and an alpha-alumina dispersion liquid obtained by performing ball milling dispersion treatment on an alpha-alumina powder prepared by the preparation method.

[0017] Further, the average particle size of the dispersed alpha-alumina nanoparticle is 130-180nm.

[0018] Further, the alpha-alumina dispersion liquid can be used for chemical mechanical polishing.

[0019] Compared with the prior art, the technical scheme has the following beneficial effects:

[0020] The present application uses aluminum ammonium sulfate as aluminum source and ammonium bicarbonate as precipitant, and obtains alpha-alumina nanopowder by acidizing the precipitant and calcining at a temperature below 1000°C without high temperature and pressure and additional additives. Further, by introducing alpha-alumina seeds into the precursor after acidizing, the calcining temperature can be further reduced, and the product is spherical alpha-alumina nanoparticles. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 X-ray diffraction spectrum of the product of Example 1;

[0022] Figure 2 X-ray diffraction spectrum of the product of Comparative Example 1. DETAILED DESCRIPTION

[0023] The advantages of the present application are further illustrated by the following specific examples.

[0024] Alumina particles of Examples 1-11 and Comparative Examples 1-3 were synthesized according to the synthesis method shown in Table 1. The examples are intended to illustrate the specific embodiments of the present application, but the scope of protection of the present application is not limited to the following examples. The specific synthesis conditions are shown as follows:

[0025] Example 1: 362.7 g of aluminum ammonium sulfate and 189.7 g of ammonium bicarbonate were dissolved in 1000 g and 1600 g of water, respectively. After stirring and dissolving, the above solutions were mixed and heated to reflux at 50°C for 6 h to obtain precursor 1. Precursor 1 was washed with deionized water 4 times and dried in an oven at 80°C for 12 h. The dried precursor 1 was ground by a grinder until it had no obvious grain feeling and weighed, and then mixed with 300 g of nitric acid, with the mass ratio of precursor 1 to nitric acid being 1:0.6 (based on the concentration of commercially available concentrated nitric acid of 68%), and the mixture was stirred at 40°C for 5 h to obtain precursor 2. After the above sample was dried in an oven at 120°C for 20 h, it was transferred to a grinder and ground for 10 min. After the sample had no obvious grain feeling, it was transferred to a corundum crucible, and the corundum crucible was placed in a muffle furnace and calcined at 950°C for 6 h, with the heating rate of the muffle furnace being 5°C / min. After natural cooling, the powder was obtained. The specific surface area of the powder was 10.1 m 2 / g, and the corresponding XRD result (attached Figure 1 ) was pure phase alpha-alumina. After ball milling and dispersion treatment, the powder could obtain alpha-alumina dispersion liquid, and the dispersed alpha-alumina nanoparticles had an average particle size of 166 nm.

[0026] Example 2: 362.7 g of aluminum ammonium sulfate and 189.7 g of ammonium bicarbonate were dissolved in 1000 g and 1600 g of water, respectively. After stirring and dissolving, the above solutions were mixed and heated to reflux at 50°C for 6 h to obtain precursor 1. Precursor 1 was washed with deionized water 4 times and then dried in an oven at 80°C for 12 h. The dried precursor 1 was ground into a powder without obvious granularity by a grinder and weighed. Then 300 g of nitric acid was mixed with the precursor 1, and the mass ratio of the precursor 1 to the nitric acid was controlled to be 1:0.6 (based on the concentration of commercially available concentrated nitric acid of 68%). The mixture was stirred at 40°C for 5 h to obtain precursor 2. Nano α-alumina was mixed into the precursor 2 as a seed crystal to further reduce the reaction temperature, and the mass ratio of the seed crystal to the aluminum ammonium sulfate used was controlled to be 1.00 wt.%. After the above sample was dried in an oven at 120°C for 20 h, it was transferred to a grinder and ground for 10 min. After the sample had no obvious granularity, it was transferred to a corundum crucible, and the corundum crucible was placed in a muffle furnace and calcined at 920°C for 6 h. The heating rate of the muffle furnace was controlled to be 5°C / min, and the powder was obtained after natural cooling. The specific surface area of the powder was tested to be 11.8 m 2 / g. The powder was treated by ball milling dispersion to obtain an α-alumina dispersion liquid, and the average particle size of the dispersed α-alumina nanoparticles was 153 nm.

[0027] Example 3: 181.4 g of aluminum ammonium sulfate and 189.7 g of ammonium bicarbonate were dissolved in 800 g and 1600 g of water, respectively. After stirring and dissolving, the above solutions were mixed and heated to reflux at 55°C for 5 h to obtain precursor 1. Precursor 1 was washed with deionized water 4 times and then placed in an oven at 80°C for drying for 12 h. The dried precursor 1 was ground into a powder without obvious granularity by a grinder and weighed. Then 150 g of nitric acid was mixed with the precursor 1 powder, and the mass ratio of the precursor 1 to the nitric acid was controlled to be 1:0.4 (based on the concentration of commercially available concentrated nitric acid of 68%). The precursor mixed with the nitric acid was heated to reflux at 90°C for 2 h to obtain precursor 2. Nano α-alumina was mixed into the precursor 2 as a seed crystal to further reduce the reaction temperature, and the mass ratio of the seed crystal to the aluminum ammonium sulfate used was controlled to be 1.13 wt.%. Then the above sample was dried in an oven at 120°C for 20 h, and the dried block was ground in a grinder for 10 min. After the sample had no obvious granularity, it was transferred to a corundum crucible, and the crucible was placed in a muffle furnace and calcined at 910°C for 8 h. The heating rate of the muffle furnace was controlled to be 5°C / min, and the powder was obtained after natural cooling. The specific surface area of the powder was tested to be 12 m 2 / g. The powder was treated by ball milling dispersion to obtain an α-alumina dispersion liquid, and the average particle size of the dispersed α-alumina nanoparticles was 153 nm.

[0028] Example 4: 295 g of aluminum ammonium sulfate and 170 g of ammonium bicarbonate were dissolved in 650 g and 2000 g of water, respectively. After stirring and dissolving, the above solutions were mixed and heated to reflux at 90°C for 3 h to obtain precursor 1. Precursor 1 was washed with deionized water for 4 times, and then was placed in an oven at 90°C for drying for 12 h. The dried precursor 1 was crushed into a powder without obvious granular feeling by a pulverizer and weighed. The precursor 1 powder was mixed with 250 g of nitric acid, and the mass ratio of the precursor 1 to the nitric acid was controlled to be 1:0.2 (based on commercially available concentrated nitric acid 68%). The precursor mixed with the nitric acid was heated to reflux at 60°C for 5 h to obtain precursor 2. Nano α-alumina was mixed into the precursor 2 as a seed crystal to further reduce the reaction temperature. The mass ratio of the seed crystal to the aluminum ammonium sulfate used was controlled to be 3.94 wt.%. Then the above sample was dried in an oven at 110°C for 20 h, and the dried block was crushed in a pulverizer for 10 min. After the sample was dried without obvious granular feeling, it was transferred to a corundum crucible. The crucible was placed in a muffle furnace, and the sample was calcined in the muffle furnace at 900°C for 6 h. The heating rate of the muffle furnace was controlled to be 10°C / min. After natural cooling, a powder was obtained. The specific surface area of the powder was tested to be 10.5 m 2 / g. The powder was treated by ball milling dispersion to obtain an α-alumina dispersion liquid. The average particle size of the dispersed α-alumina nanoparticles was 145 nm.

[0029] Example 5: 250 g of aluminum ammonium sulfate and 281.1 g of ammonium bicarbonate were dissolved in 900 g and 1390 g of water, respectively. After stirring and dissolving, the above solutions were mixed and heated to reflux at 75°C for 5 h to obtain precursor 1. Precursor 1 was washed with deionized water for 4 times, and then was placed in an oven at 80°C for drying for 13 h. The dried precursor 1 was crushed into a powder without obvious granular feeling by a pulverizer and weighed. The precursor 1 powder was mixed with 200 g of nitric acid, and the mass ratio of the precursor 1 to the nitric acid was controlled to be 1:2 (based on commercially available concentrated nitric acid 68%). The precursor mixed with the nitric acid was heated to reflux at 80°C for 6 h to obtain precursor 2. The above sample was dried in an oven at 120°C for 21 h. Then the dried block was crushed in a pulverizer for 15 min. After the sample was dried without obvious granular feeling, it was transferred to a corundum crucible. The crucible was placed in a muffle furnace, and the sample was calcined in the muffle furnace at 930°C for 8 h. The heating rate of the muffle furnace was controlled to be 5°C / min. After natural cooling, a powder was obtained. The specific surface area of the powder was tested to be 11.6 m 2 / g. The powder was treated by ball milling dispersion to obtain an α-alumina dispersion liquid. The average particle size of the dispersed α-alumina nanoparticles was 155 nm.

[0030] Example 6: 225.6 g of ammonium aluminum sulfate and 165.3 g of ammonium bicarbonate were dissolved in 860 g and 1300 g of water, respectively. After stirring and dissolving, the solutions were mixed and heated under reflux at 70°C for 2 hours to obtain precursor 1. Precursor 1 was washed four times with deionized water and then dried in an oven at 80°C for 12 hours. The dried precursor 1 was pulverized into a powder with no obvious particle texture and weighed. The precursor 1 powder was mixed with 180 g of nitric acid, controlling the mass ratio of precursor 1 to nitric acid to be 1:0.4 (based on commercially available concentrated nitric acid 68%). The precursor mixed with nitric acid was heated under reflux at 75°C for 5 hours to obtain precursor 2. Nano-alumina was incorporated into precursor 2 as a seed crystal to further reduce the reaction temperature. The mass ratio of the seed crystal to ammonium aluminum sulfate was controlled at 1.35 wt.%. The sample was then dried in an oven at 100°C for 24 hours. The dried block was then pulverized in a pulverizer for 12 minutes. After the sample was completely dry and free of obvious particles, it was transferred to a corundum crucible. The crucible was placed in a muffle furnace and calcined at 900°C for 5 hours, with the heating rate controlled at 3°C / min. After natural cooling, the powder was obtained. The powder had a specific surface area of ​​11.0 m². 2 / g. After ball milling and dispersion, the powder can be used to obtain an α-alumina dispersion, and the dispersed α-alumina nanoparticles have an average particle size of 149nm.

[0031] Example 7: 290.5g of ammonium aluminum sulfate and 289g of ammonium bicarbonate were dissolved in 700g and 2000g of water, respectively. After stirring and dissolving, the solutions were mixed and heated under reflux at 60°C for 3 hours to obtain precursor 1. Precursor 1 was washed four times with deionized water and then dried in an oven at 80°C for 12 hours. The dried precursor 1 was pulverized into a powder with no obvious particle texture and weighed. The precursor 1 powder was mixed with 230g of nitric acid, controlling the mass ratio of precursor 1 to nitric acid to be 1:0.9 (based on commercially available concentrated nitric acid 68%). The precursor mixed with nitric acid was heated under reflux at 85°C for 7 hours to obtain precursor 2. Nano-alumina was incorporated into precursor 2 as a seed crystal to further reduce the reaction temperature. The mass ratio of the seed crystal to ammonium aluminum sulfate was controlled at 1.69 wt.%. The sample was then dried in an oven at 120°C for 24 hours. The dried block was then pulverized in a pulverizer for 15 minutes. After the sample was completely dry and free of visible particles, it was transferred to a corundum crucible. The crucible was placed in a muffle furnace and calcined at 950°C for 4 hours, with the heating rate controlled at 8°C / min. After natural cooling, the powder was obtained. The powder had a specific surface area of ​​9.8 m². 2 / g. After ball milling and dispersion, the powder can be used to obtain an α-alumina dispersion, and the dispersed α-alumina nanoparticles can have an average particle size of 170nm.

[0032] Example 8: 159.5 g of aluminum ammonium sulfate and 150.3 g of ammonium bicarbonate were dissolved in 500 g and 1500 g of water, respectively. After stirring and dissolving, the above solutions were mixed and heated to reflux at 65°C for 3 h to obtain precursor 1. Precursor 1 was washed with deionized water 4 times and then placed in an oven at 70°C for drying for 12 h. The dried precursor 1 was ground into a powder without obvious granular feeling by a grinder and weighed. The precursor 1 powder was mixed with 130 g of nitric acid, and the mass ratio of precursor 1 to nitric acid was controlled to be 1:0.6 (based on commercially available concentrated nitric acid 68%). The precursor mixed with nitric acid was heated to reflux at 50°C for 8 h to obtain precursor 2. Nano α-alumina was mixed into the above precursor 2 as a seed crystal to further reduce the reaction temperature. The mass ratio of the seed crystal to the aluminum ammonium sulfate used was controlled to be 5.6 wt.%. Then the above sample was dried in an oven at 120°C for 20 h, the dried block was ground in a grinder for 13 min, and the sample was transferred to a corundum crucible. The crucible was placed in a muffle furnace, and the sample was calcined in the muffle furnace at 880°C for 5 h. The heating rate of the muffle furnace was controlled to be 10°C / min. After natural cooling, the powder was obtained. The specific surface area of the powder was tested to be 14.2 m 2 / g. The powder was treated by ball milling dispersion to obtain an α-alumina dispersion liquid. The average particle size of the dispersed α-alumina nanoparticles was 138 nm.

[0033] Example 9: 310.5 g of aluminum ammonium sulfate and 200.6 g of ammonium bicarbonate were dissolved in 719 g and 1800 g of water, respectively. After stirring and dissolving, the above solutions were mixed and heated to reflux at 50°C for 7 h to obtain precursor 1. Precursor 1 was washed with deionized water 4 times and then placed in an oven at 80°C for drying for 13 h. The dried precursor 1 was ground into a powder without obvious granular feeling by a grinder and weighed. The precursor 1 powder was mixed with 255 g of nitric acid, and the mass ratio of precursor 1 to nitric acid was controlled to be 1:0.03 (based on commercially available concentrated nitric acid 68%). The precursor mixed with nitric acid was heated to reflux at 70°C for 5 h to obtain precursor 2. The above sample was dried in an oven at 120°C for 21 h, the dried block was ground in a grinder for 15 min, and the sample was transferred to a corundum crucible. The crucible was placed in a muffle furnace, and the sample was calcined in the muffle furnace at 980°C for 10 h. The heating rate of the muffle furnace was controlled to be 6°C / min. After natural cooling, the powder was obtained. The specific surface area of the powder was tested to be 13.8 m 2 / g. The powder was treated by ball milling dispersion to obtain an α-alumina dispersion liquid. The average particle size of the dispersed α-alumina nanoparticles was 180 nm.

[0034] Example 10: 275g of ammonium aluminum sulfate and 192g of ammonium bicarbonate were dissolved in 720g and 1750g of water, respectively. After stirring and dissolving, the solutions were mixed and heated under reflux at 40°C for 8 hours to obtain precursor 1. Precursor 1 was washed four times with deionized water and then dried in an oven at 80°C for 12 hours. The dried precursor 1 was pulverized into a powder with no obvious particle texture and weighed. The precursor 1 powder was mixed with 220g of nitric acid, controlling the mass ratio of precursor 1 to nitric acid to be 1:0.36 (based on commercially available concentrated nitric acid 68%). The precursor mixed with nitric acid was heated under reflux at 45°C for 7 hours to obtain precursor 2. Nano-alumina was incorporated into precursor 2 as a seed crystal to further reduce the reaction temperature. The mass ratio of the seed crystal to ammonium aluminum sulfate was controlled at 0.34 wt.%. The sample was then dried in an oven at 120°C for 20 hours. The dried block was then pulverized in a pulverizer for 15 minutes. After the sample was completely dry and free of obvious particles, it was transferred to a corundum crucible. The crucible was placed in a muffle furnace and calcined at 950°C for 8 hours, with the heating rate controlled at 10°C / min. After natural cooling, the powder was obtained. The powder had a specific surface area of ​​11.9 m². 2 / g. After ball milling and dispersion, the powder can be used to obtain an α-alumina dispersion, and the dispersed α-alumina nanoparticles have an average particle size of 159nm.

[0035] Example 11: 340.9 g of ammonium aluminum sulfate and 195.9 g of ammonium bicarbonate were dissolved in 1100 g and 1650 g of water, respectively. After stirring and dissolving, the solutions were mixed and heated under reflux at 80°C for 6 h to obtain precursor 1. Precursor 1 was washed four times with deionized water and then dried in an oven at 80°C for 15 h. The dried precursor 1 was pulverized into a powder with no obvious particle texture and weighed. The precursor 1 powder was mixed with 270 g of nitric acid, controlling the mass ratio of precursor 1 to nitric acid to be 1:0.56 (based on commercially available concentrated nitric acid 68%). The precursor mixed with nitric acid was heated under reflux at 85°C for 3 h to obtain precursor 2. The above sample was dried in an oven at 120℃ for 24 hours. The dried block was then pulverized in a pulverizer for 15 minutes. After the sample was completely dry and free of obvious particles, it was transferred to a corundum crucible. The crucible was then placed in a muffle furnace and calcined at 930℃ for 6 hours, with the heating rate of the muffle furnace controlled at 10℃ / min. After natural cooling, the powder was obtained. The specific surface area of ​​the powder was measured to be 14.9 m². 2 / g. After ball milling and dispersion, the powder can be used to obtain an α-alumina dispersion, and the dispersed α-alumina nanoparticles have an average particle size of 162nm.

[0036] Comparative Example 1: 362.7 g of aluminum ammonium sulfate and 189.7 g of ammonium bicarbonate were dissolved in 1000 g and 1600 g of water, respectively. After stirring and dissolving, the above solutions were mixed and heated to reflux at 50°C for 6 h to obtain precursor 1. The precursor 1 was washed with deionized water for 4 times and then transferred to an oven at 80°C for drying for 12 h. After drying, the sample was transferred to a pulverizer and pulverized for 10 min. After the sample was not obviously granular, it was transferred to a corundum crucible. The corundum crucible was placed in a muffle furnace and calcined at 950°C for 6 h, with a muffle furnace heating rate of 5°C / min. After natural cooling, a powder was obtained. The specific surface area of the powder was 123 m 2 / g, and the sample was not completely converted into α-alumina, which was consistent with the XRD results (see attached Figure 2 ). Compared with Example 1, there was no reaction with nitric acid, i.e., the precursor 1 was directly washed, dried, and calcined. Under the same calcination conditions, the specific surface area of Comparative Example 1 was larger and not completely converted into α-phase.

[0037] Comparative Example 2: 295 g of aluminum ammonium sulfate and 170 g of ammonium bicarbonate were dissolved in 650 g and 2000 g of water, respectively. After stirring and dissolving, the above solutions were mixed and heated to reflux at 90°C for 3 h to obtain precursor 1. The precursor 1 was washed with deionized water for 4 times, and then nano α-alumina was mixed into the precursor 1 as a seed crystal, with a mass ratio of the seed crystal to the used aluminum ammonium sulfate of 3.94 wt.%. Then, the sample was dried in an oven at 110°C for 20 h, and the block-shaped dried sample was pulverized in a pulverizer for 10 min. After the sample was not obviously granular, it was transferred to a corundum crucible. The crucible was placed in a muffle furnace and calcined at 900°C for 6 h, with a muffle furnace heating rate of 10°C / min. After natural cooling, a powder was obtained. The specific surface area of the powder was 95 m 2 / g, and the sample was not completely converted into α-alumina. Compared with Example 4, there was no reaction with nitric acid, and even with the assistance of the seed crystal, under the same calcination conditions, the specific surface area of Comparative Example 2 was larger and not completely converted into α-phase.

[0038] Comparative Example 3: 362.7 g of aluminum ammonium sulfate and 189.7 g of ammonium bicarbonate were dissolved in 1000 g and 1600 g of water, respectively, and after stirring and dissolving, the above solutions were mixed and heated to reflux at 50°C for 6 h to obtain precursor 1. Precursor 1 was washed with deionized water 4 times and then dried in an oven at 80°C for 12 h. The dried precursor 1 was ground in a pulverizer until no obvious particles were felt, and then mixed with 300 g of nitric acid, with the mass ratio of precursor 1 to nitric acid being 1:0.01 (based on the concentration of commercially available concentrated nitric acid being 68%), and the mixture was stirred at 40°C for 5 h to obtain precursor 2. After the above sample was dried in an oven at 120°C for 20 h, it was transferred to a pulverizer and ground for 10 min. After the sample was ground until no obvious particles were felt, it was transferred to a corundum crucible, and the corundum crucible was placed in a muffle furnace and calcined at 950°C for 6 h, with the heating rate of the muffle furnace being 5°C / min. After natural cooling, a powder was obtained. The powder was tested and the specific surface area was 58 m 2 / g, i.e., the phase transformation was insufficient in the case of too little nitric acid. According to the specific surface area results, the amount of nitric acid used in Comparative Example 3 was less than that used in Example 1, and it was not completely transformed into the α phase, but the degree of phase transformation was still higher than that of Comparative Example 1 (123 m 2 / g) which was not treated with nitric acid.

[0039]

[0040] The aluminum oxide particles of Examples 1-11 and Comparative Examples 1-3 were synthesized by the method shown in Table 1. From the experimental results, it can be seen that Comparative Example 1 did not have a reaction process with nitric acid, i.e., precursor 1 was directly washed, dried, and calcined. Under the same calcination conditions, the specific surface area of Comparative Example 1 was large and it was not completely transformed into the α phase; Comparative Example 2 did not have a reaction process with nitric acid, i.e., even with the assistance of seed crystals, under the same calcination conditions, the specific surface area of Comparative Example 2 was large and it was not completely transformed into the α phase; the powder obtained in Comparative Example 3 was tested and the specific surface area was 58 m 2 / g, i.e., the phase transformation was insufficient in the case of too little nitric acid. According to the specific surface area results, the amount of nitric acid used in Comparative Example 3 was less than that used in Example 1, and it was not completely transformed into the α phase, but the degree of phase transformation was still higher than that of Comparative Example 1 (123 m 2 / g) which was not treated with nitric acid. Therefore, it can be seen that after the synthesis of precursor 1, the concentration and amount of nitric acid used in the acidification process are key factors. Furthermore, the introduction of α-alumina seed crystals into the precursor after acidification can further reduce the calcination temperature.

[0041] The application uses aluminum ammonium sulfate as an aluminum source and ammonium bicarbonate as a precipitant, and obtains alpha-alumina nano powder by calcining the precipitant under the condition of less than 1000 DEG C without high temperature and pressure and additional additives, and the product is spherical alpha-alumina nanoparticles. The alumina dispersion liquid obtained by dispersing the alpha-alumina nanoparticles can be applied to the fields of integrated circuit chemical mechanical polishing and lithium battery separator coating.

[0042] It should be noted that the embodiments of the present application have better implementation, and do not limit the present application in any form, and any skilled person in the art can change or modify the above disclosed technical content into equivalent effective embodiments, as long as the content is not deviated from the technical solution of the present application, and any modification or equivalent change and modification of the above embodiments according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A method for synthesizing α-alumina nanoparticles, characterized in that, include: S1) Dissolve ammonium aluminum sulfate and ammonium bicarbonate separately in water, stir and dissolve them separately, then mix the two solutions to obtain a mixed solution with a certain concentration ratio. The mixed solution is reacted at a first temperature T1 and after a first time t1, precursor 1 is obtained. Precursor 1 is washed with water and then dried. S2) After the dried precursor 1 is crushed, it is mixed with nitric acid at a certain mass ratio and stirred. After reacting at a second temperature T2 and a second time t2, precursor 2 is obtained. S3) After drying and pulverizing the precursor 2, it was calcined in a muffle furnace at a third temperature T3 for a third time t3, and then naturally cooled to obtain α-alumina powder.

2. The synthesis method according to claim 1, characterized in that, In S1, the molar ratio of ammonium aluminum sulfate to ammonium bicarbonate is 1:3.0 to 1:6.

0.

3. The synthesis method as described in claim 1, characterized in that, In S1, T1 is 50℃-90℃; t1 is 2h-8h.

4. The synthesis method according to claim 1, characterized in that, In S1, precursor 1 is washed with water and then dried in an oven at 80°C for 12-15 hours.

5. The synthesis method according to claim 1, characterized in that, In S2, the mass ratio of precursor 1 to nitric acid (based on commercially available concentrated nitric acid with a concentration of 68%) is 1:0.03 to 1:

2.

6. The synthesis method as described in claim 5, characterized in that, In S2, the mass ratio of precursor 1 to nitric acid (based on a commercially available concentrated nitric acid concentration of 68%) is 1:0.2 to 1:0.

9.

7. The synthesis method according to claim 1, characterized in that, In S2, T2 is 40℃-90℃; t2 is 2h-8h.

8. The synthesis method according to claim 1, characterized in that, In S3, T3 is 880℃-980℃; t3 is 4h-10h.

9. The synthesis method according to claim 1, characterized in that, S2 also includes: S2') In the precursor 2, α-alumina seed crystals are mixed in, and the mass ratio of seed crystals to ammonium aluminum sulfate is controlled. Then the mixture is dried and pulverized.

10. The synthesis method according to claim 9, characterized in that, The mass ratio of seed crystals to ammonium aluminum sulfate is 0.1 wt.% to 5.6 wt.%.

11. The synthesis method according to claim 10, characterized in that, The mass ratio of seed crystals to ammonium aluminum sulfate is 0.34 wt.% to 3.94 wt.%.

12. The synthesis method according to claim 1, characterized in that, In S3, the heating rate of the muffle furnace is 5℃ / min-10℃ / min.

13. An α-alumina nanoparticle synthesized by the synthesis method according to any one of claims 1-12.

14. The α-alumina powder prepared by the preparation method of any one of claims 1-12 is subjected to ball milling dispersion treatment to obtain an α-alumina dispersion.

15. The dispersion as described in claim 14, characterized in that, The average particle size of the dispersed α-alumina nanoparticles is 130-180 nm.

16. Use of the α-alumina dispersion of claim 15 for chemical mechanical polishing.

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