CN114715925A - Flaky alpha alumina and preparation method thereof - Google Patents
Flaky alpha alumina and preparation method thereof Download PDFInfo
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- CN114715925A CN114715925A CN202210420492.4A CN202210420492A CN114715925A CN 114715925 A CN114715925 A CN 114715925A CN 202210420492 A CN202210420492 A CN 202210420492A CN 114715925 A CN114715925 A CN 114715925A
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 title claims abstract description 85
- 238000002360 preparation method Methods 0.000 title claims abstract description 24
- 239000000203 mixture Substances 0.000 claims abstract description 32
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 22
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 22
- 150000003839 salts Chemical class 0.000 claims abstract description 21
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 claims abstract description 19
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 claims abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 238000001035 drying Methods 0.000 claims abstract description 13
- 238000004519 manufacturing process Methods 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- 239000002245 particle Substances 0.000 claims abstract description 10
- 238000005303 weighing Methods 0.000 claims abstract description 9
- 238000001132 ultrasonic dispersion Methods 0.000 claims abstract description 8
- 239000008367 deionised water Substances 0.000 claims abstract description 6
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 6
- 238000000227 grinding Methods 0.000 claims abstract description 6
- 239000004570 mortar (masonry) Substances 0.000 claims abstract description 6
- 235000002639 sodium chloride Nutrition 0.000 claims description 27
- 238000000034 method Methods 0.000 claims description 21
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 16
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 16
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 8
- 235000011164 potassium chloride Nutrition 0.000 claims description 8
- 239000001103 potassium chloride Substances 0.000 claims description 8
- 239000011780 sodium chloride Substances 0.000 claims description 8
- 229910001593 boehmite Inorganic materials 0.000 claims description 3
- 229910001648 diaspore Inorganic materials 0.000 claims description 3
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 3
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 2
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims description 2
- 229910052939 potassium sulfate Inorganic materials 0.000 claims description 2
- 235000011151 potassium sulphates Nutrition 0.000 claims description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 2
- 235000011152 sodium sulphate Nutrition 0.000 claims description 2
- 239000000843 powder Substances 0.000 abstract description 5
- 230000035484 reaction time Effects 0.000 abstract 1
- 239000000047 product Substances 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 9
- 239000013078 crystal Substances 0.000 description 9
- 238000002441 X-ray diffraction Methods 0.000 description 6
- 238000004321 preservation Methods 0.000 description 6
- 238000007605 air drying Methods 0.000 description 5
- 238000001354 calcination Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 238000001000 micrograph Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000010532 solid phase synthesis reaction Methods 0.000 description 3
- 238000000967 suction filtration Methods 0.000 description 3
- 239000006228 supernatant Substances 0.000 description 3
- 238000009210 therapy by ultrasound Methods 0.000 description 3
- 238000004506 ultrasonic cleaning Methods 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910001338 liquidmetal Inorganic materials 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910000873 Beta-alumina solid electrolyte Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 229940103272 aluminum potassium sulfate Drugs 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- -1 flexibilizers Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000010297 mechanical methods and process Methods 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- GRLPQNLYRHEGIJ-UHFFFAOYSA-J potassium aluminium sulfate Chemical compound [Al+3].[K+].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GRLPQNLYRHEGIJ-UHFFFAOYSA-J 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000012429 reaction media Substances 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910006587 β-Al2O3 Inorganic materials 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/30—Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Nanotechnology (AREA)
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- Crystallography & Structural Chemistry (AREA)
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- Geology (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Composite Materials (AREA)
- Materials Engineering (AREA)
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Abstract
The invention provides a preparation method of flaky alpha alumina, which comprises the following steps: (1) weighing molten salt and an aluminum source, placing the molten salt and the aluminum source in a container, adding deionized water to dissolve, performing ultrasonic dispersion uniformly, and drying to obtain a mixture; (2) placing the mixture dried in the step (1) in a mortar, adding aluminum fluoride, and grinding uniformly; (3) and (3) placing the powder in the step (2) into a crucible, placing the crucible into a heating furnace, heating to the temperature of 750-. The preparation method of the flaky alpha alumina has the advantages of low preparation temperature and short reaction time, and greatly reduces the production cost. The invention also provides the flaky alpha alumina prepared by the preparation method of the flaky alpha alumina, wherein the average radial size of particles of the flaky alpha alumina is 4-5 mu m, the thickness is 150-250nm, and the ratio of the diameter to the thickness is 16-25.
Description
Technical Field
The invention belongs to the technical field of preparation of aluminum oxide, and particularly relates to flaky alpha aluminum oxide and a preparation method thereof.
Background
Alumina is a common material for making refractory materials due to its high hardness and high melting point, its melting point is 2054 deg.C and its boiling point is as high as2980 ℃. The flake alumina as functional material with excellent performance has all the advantages of common alumina and unique flake structure, so that it has the double features of micron powder and nanometer powder. The flaky alumina is mainly gamma-Al in the industry2O3、β-Al2O3、α-Al2O3(commonly known as corundum) of these 3 crystal forms; with the increase of temperature, the crystal form of the crystal form can be finally converted into alpha alumina from gamma or beta alumina, the most stable crystal form of the three crystal forms is alpha alumina, the only crystal form can stably exist at any temperature below a melting point, and other crystal forms are almost completely converted into alpha alumina at high temperature (above 1000 ℃).
Compared with most natural materials, the artificially synthesized flaky alpha alumina has more advantages in properties, and the artificially synthesized alpha alumina powder has high purity, smooth surface and difficult agglomeration in water. The flaky alumina has wide application prospect in the fields of fillers, flexibilizers, cosmetics, heat conduction materials and the like. The conventional preparation methods of the flaky alpha alumina include a high-temperature sintering method, a hydrothermal method, a sol-gel method, a mechanical method, a molten salt method and the like. The molten salt method has the advantages of simple process, uniform components, good and controllable crystal morphology, good phase purity and the like, becomes a main method for preparing the flaky alumina, and needs high-temperature sintering in the process of preparing the flaky alumina by the molten salt method, the sintering temperature is about 1200 ℃, the heat preservation time is 3-5h, the sintering temperature is high, the heat preservation time is long, the energy consumption is high, and the cost is increased. The high temperature solid phase method has the same simple process and good phase purity, but the calcination temperature is high, 1200-1500 ℃, the product dispersibility is not good, and the common preparation process of the high temperature solid phase method is to roast alumina as a raw material and 10 wt% or more of aluminum fluoride as an additive for more than 3 hours at the temperature of more than 1200 ℃ to prepare the flaky alpha alumina.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide the preparation method of the flaky alpha alumina, the method adopts the molten salt as a reaction medium, aluminum fluoride is added to form an aluminum fluoride molten salt system, the preparation of the flaky alpha alumina is carried out, the reaction temperature is low, the heat preservation time is short, and the production cost is greatly reduced. The invention also provides the flaky alpha alumina prepared by the preparation method.
The technical scheme adopted by the invention is as follows:
a preparation method of flaky alpha alumina comprises the following steps:
(1) weighing molten salt and an aluminum source, placing the molten salt and the aluminum source in a container, adding deionized water to dissolve, and drying after uniform ultrasonic dispersion to obtain a mixture A;
(2) placing the mixture A dried in the step (1) in a mortar, adding aluminum fluoride, and grinding uniformly to obtain a mixture B;
(3) and (3) placing the mixture B in the step (2) into a crucible, placing the crucible into a heating furnace, heating to the temperature of 750-.
The preparation method of the flaky alpha alumina, disclosed by the invention, comprises the step (1) of preparing the flaky alpha alumina, wherein the aluminum source is one or more of aluminum hydroxide, diaspore and boehmite.
The preparation method of the flaky alpha alumina comprises the step (1), wherein the molten salt is one or more of sodium sulfate, sodium chloride, potassium sulfate and potassium chloride.
The method for preparing flaky alpha alumina, provided by the invention, is characterized in that the molten salt in the step (1) is 3-10 times of the aluminum source in mass.
The preparation method of the flaky alpha alumina, disclosed by the invention, comprises the following steps of (1) taking an aluminum source as aluminum hydroxide; the molten salt is one or two of sodium chloride and potassium chloride, and the mass ratio of the two molten salts is 1: 1.
The method for producing flaky alpha alumina of the present invention is characterized in that the amount of aluminum fluoride added in step (2) is 2 to 9 wt% based on the amount of the aluminum source.
The method for preparing flaky alpha alumina, disclosed by the invention, is characterized in that the adding amount of the aluminum fluoride in the step (2) is 4-6 wt% of the aluminum source.
The preparation method of the flaky alpha alumina, provided by the invention, comprises the steps of heating to 900 ℃ at 750-.
The preparation method of the flaky alpha alumina comprises the step (3), wherein the temperature is heated to 750 ℃ and is preserved for 3 hours, or the temperature is preserved for 1 hour at 800 ℃ or the temperature is preserved for 0.5 hour at 900 ℃.
The invention also provides the flaky alpha alumina prepared by the preparation method of the flaky alpha alumina, wherein the average radial size of particles of the flaky alpha alumina is 4-5 mu m, the thickness is 150-250nm, and the ratio of the diameter to the thickness is 16-25.
The invention has the beneficial effects that:
1. the product prepared by the method has a large diameter-thickness ratio which can reach more than 20; the product with large radius-thickness ratio can be used as pearlescent pigment in certain application fields to improve the effect and reduce the dosage.
2. The method has the advantages of low calcination temperature, short heat preservation time, short calcination temperature, low energy consumption and low production cost, flaky alpha alumina can be generated at 750 ℃, flaky alpha alumina can be generated at 800 ℃ after heat preservation for 60min, flaky alpha alumina can be generated at 900 ℃ after heat preservation for 30 min. The melting point of a composite system consisting of the molten salt and the aluminum fluoride is low, the composite system can exist in a liquid state at 750 ℃, the reaction is carried out in the liquid molten salt, and the diffusion rate of substances is increased, so that the reaction is accelerated.
3. The invention has the advantages of easily obtained raw materials, low price, simple process and low production cost.
4. Compared with the method for preparing the flaky alpha alumina by a high-temperature solid phase method, the method disclosed by the invention can be used for preparing the flaky alpha alumina with good dispersibility by only adding a small amount of aluminum fluoride, the addition amount of the aluminum fluoride is reduced, and the possibility of environmental pollution is reduced.
5. The aluminum source is aluminum hydroxide, diaspore and boehmite, wherein the aluminum source only contains three elements of aluminum, hydrogen and oxygen, even though a by-product is generated by reaction with liquid metal in the reaction process, the by-product can be metal oxide or hydroxide without introducing other impurities, the hydroxide is finally oxide at high temperature, and the simple substance aluminum in the liquid metal can react with other metal oxides to be replaced, so that the impurities cannot be introduced into the product. Experimental research shows that flaky alumina generated by using alumina as an aluminum source is seriously agglomerated and can be generated only by adding a high amount of aluminum fluoride, and sulfur-containing impurities generated by using aluminum sulfate, aluminum potassium sulfate and the like as the aluminum source are mixed in the product.
Drawings
FIG. 1a is a scanning electron microscope photograph at 5000 Xmagnification of the product prepared in example 1;
FIG. 1b is a scanning electron microscope photograph at 2500 Xmagnification of the product prepared in example 1;
FIG. 1c is a scanning electron microscope photograph at 20000 magnification of the product prepared in example 1;
FIG. 1d is the XRD pattern of the product prepared in example 1;
FIG. 2a is a scanning electron microscope photograph at 5000 Xmagnification of the product prepared in example 2;
figure 2b is the XRD pattern of the product prepared in example 2;
FIG. 3a is a scanning electron microscope photograph at 5000 Xmagnification of the product prepared in example 3;
figure 3b is an XRD pattern of the product prepared in example 3;
FIG. 4 is a 2500 times magnified scanning electron microscope image of the product prepared in comparative example 1;
FIG. 5 is a 2500 times magnified scanning electron microscope image of the product prepared in comparative example 2;
fig. 6 is a scanning electron microscope photograph of the product prepared in comparative example 3, magnified 2500 times.
The invention will be further illustrated with reference to specific embodiments and the accompanying drawings.
Detailed Description
In the following examples, alpha-Al was observed by using a scanning electron microscope of model SU5000 from Hitachi corporation2O3Sample morphology, with a test voltage of 5 KV; alpha-Al is measured by a Rigaku D-MAX/2500V X-ray powder diffractometer2O3Sample crystal forms, and the determination conditions are as follows: cu Kalpha radiation, a graphite monochromator, tube voltage of 40KV, tube current of 160mA, 2 theta scanning range of 20-80 degrees and scanning speed of 6 degrees/min.
Example 1
A preparation method of flaky alpha alumina comprises the following steps:
(1) weighing 4.5g of sodium chloride and 2g of potassium chloride and 2g of aluminum hydroxide respectively, placing the sodium chloride and the potassium chloride into a beaker, adding 100mL of deionized water, ultrasonically dispersing the mixture uniformly, then placing the beaker into a forced air drying oven, drying the beaker for 3 hours at 120 ℃, and cooling the beaker to obtain a mixture A;
(2) weighing 0.1g of aluminum fluoride and the mixture A in the step (1), putting the mixture A into an alumina mortar, and uniformly grinding to obtain a mixture B;
(3) transferring the mixture B in the step (2) into an alumina crucible, then putting the alumina crucible into a box-type resistance furnace, calcining the mixture for 180min at the temperature of 750 ℃, wherein the heating rate is 9 ℃/min, taking out the alumina crucible after the sample is cooled to the room temperature, and transferring the sample in the alumina crucible to a beaker;
adding 300-400mL of water into the beaker, placing the beaker into an ultrasonic cleaning machine, performing ultrasonic dispersion and dissolution, standing for 6 hours to remove supernatant or performing suction filtration after the water is completely dissolved, adding water into the obtained sample for cleaning, performing ultrasonic treatment, repeating the steps for 3 times, placing the obtained sample into a 100-120 ℃ air blast drying oven for drying, and obtaining the flaky alpha alumina sample after the drying is completed.
FIGS. 1(a), (b) and (c) are SEM images magnified by 5000, 2500 and 20000 times respectively for the samples prepared in this example, and it can be seen that the alumina produced is flaky, regular in morphology, hexagonal in shape, with a radial size of 2.23 μm to 9.44 μm, an average radial size of about 5 μm, a thickness of about 230nm, and a aspect ratio of about 21; the particle size is uniform.
Fig. 1(d) is an XRD pattern of the sample prepared in this example, and comparing PDF cards (PDF #74-1801) can determine that the prepared sample is alpha alumina.
Example 2
A preparation method of flaky alpha alumina comprises the following steps:
(1) weighing 4.5g of sodium chloride and 2g of potassium chloride and 2g of aluminum hydroxide respectively, placing the mixture into a beaker, adding 100mL of deionized water, performing ultrasonic dispersion uniformly, then placing the beaker into a forced air drying oven, drying the beaker at 120 ℃ for 3 hours, and cooling to prepare a mixture A;
(2) weighing 0.1g of aluminum fluoride and the mixture A in the step (1), putting the mixture A into an alumina mortar, and uniformly grinding to obtain a mixture B;
(3) transferring the mixture B in the step (2) into an alumina crucible, then placing the mixture into a box-type resistance furnace to calcine at 800 ℃ for 60min at a heating rate of 9 ℃/min, taking out the alumina crucible after the sample is cooled to room temperature, and transferring the sample in the alumina crucible to a beaker;
adding 300-400mL of water into the beaker, placing the beaker into an ultrasonic cleaning machine, performing ultrasonic dispersion and dissolution, standing for 6 hours to remove supernatant or performing suction filtration after the water is completely dissolved, adding water into the obtained sample for cleaning, performing ultrasonic treatment, repeating the steps for 3 times, placing the obtained sample into a forced air drying oven for drying at the temperature of 100-120 ℃, and obtaining the flaky alpha alumina sample after the drying is completed.
FIG. 2(a) is a scanning electron microscope image magnified 5000 times of the sample prepared in this example, and it can be seen that the generated alumina is flaky, regular in morphology, hexagonal, with a radial size of 1.59 μm to 5.88 μm, an average radial size of about 4 μm, a thickness of about 220nm, and a aspect ratio of about 18; the particle size is uniform.
Fig. 2(b) is an XRD pattern of the sample prepared in this embodiment, and the comparison with PDF card (PDF #74-1801) can indicate that the prepared sample is α -alumina.
Example 3
A preparation method of flaky alpha alumina comprises the following steps:
(1) weighing 4.5g of sodium chloride and 2g of potassium chloride and 2g of aluminum hydroxide respectively, placing the mixture into a beaker, adding 100mL of deionized water, performing ultrasonic dispersion uniformly, then placing the beaker into a forced air drying oven, drying the beaker at 120 ℃ for 3 hours, and cooling to prepare a mixture A;
(2) weighing 0.1g of aluminum fluoride and the mixture A in the step (1), putting the mixture A into an alumina mortar, and uniformly grinding to obtain a mixture B;
(3) transferring the mixture B in the step (2) into an alumina crucible, then putting the alumina crucible into a box-type resistance furnace, calcining the mixture for 30min at the temperature of 900 ℃, heating up at the rate of 9 ℃/min, taking out the crucible after the sample is cooled to the room temperature, and transferring the sample in the crucible to a beaker;
adding 300-400mL of water into the beaker, putting the beaker into an ultrasonic cleaning machine, performing ultrasonic dispersion and dissolution, standing the beaker for 6 hours to remove supernatant or performing suction filtration after the water is completely dissolved, adding water into the obtained sample for cleaning, performing ultrasonic treatment, repeating the steps for 3 times, putting the obtained sample into a forced air drying oven for drying at the temperature of 100-400 ℃, and obtaining the flaky alpha-Al after the drying is finished2O3And (3) sampling.
FIG. 3(a) is a scanning electron microscope image of the sample prepared in this example, magnified 5000 times, and it can be seen that the generated alumina is flaky, regular in morphology, hexagonal, and has a radial size of 1.71 μm to 7.81 μm, an average radial size of about 4 μm, a thickness of about 200nm, and a ratio of diameter to thickness of about 20; the particle size is uniform.
Fig. 3(b) is an XRD pattern of the sample prepared in this example, and comparing PDF cards (PDF #74-1801) can determine that the prepared sample is alpha alumina.
Comparative example 1
A method for producing flaky alpha alumina, which was the same as in example 1 except that the mass of aluminum fluoride was 0.05 g.
FIG. 4 is a scanning electron microscope photograph at 2500 times magnification of the sample prepared in this comparative example, and it can be seen that the prepared samples are all in the form of thick plates with well-defined edges and corners, the plane in the thickness is trapezoidal, the radial dimension of the particle diameter is 1.99 μm to 6.06 μm, the average radial dimension is about 3.4 μm, and the thickness of the particle is about 1.2. mu.m.
Comparative example 2
A method for producing flaky alpha alumina, which was the same as in example 1 except that the mass of aluminum fluoride was 0.25 g.
FIG. 5 is a scanning electron microscope photograph of 2500 times magnification of the sample prepared by this comparative example, and it can be seen that the prepared sample is still flaky, but the morphology of the sample is no longer hexagonal, the edge is passivated and becomes flaky, the particle size of the flaky alumina is in the range of 1.54 μm to 5.40 μm in radial dimension, and the average radial dimension is around 3 μm.
Comparative example 3
A method for preparing flaky alpha alumina, which is the same as in example 1 except that the temperature in step (2) is 700 ℃.
Fig. 6 is a scanning electron microscope photograph at 2500 times magnification of the sample prepared in this comparative example, and it can be seen that the prepared product was irregular granular shape, large in particle size, about 20 μm, and no flaky alumina was generated.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.
Claims (10)
1. A preparation method of flaky alpha alumina is characterized by comprising the following steps: the method comprises the following steps:
(1) weighing molten salt and an aluminum source, placing the molten salt and the aluminum source in a container, adding deionized water to dissolve, and drying after uniform ultrasonic dispersion to obtain a mixture A;
(2) placing the mixture A dried in the step (1) in a mortar, adding aluminum fluoride, and grinding uniformly to obtain a mixture B;
(3) and (3) placing the mixture B in the step (2) into a crucible, placing the crucible into a heating furnace, heating to the temperature of 750-.
2. The method for producing flaky alpha alumina according to claim 1, characterized in that: in the step (1), the aluminum source is one or more of aluminum hydroxide, diaspore and boehmite.
3. The method for preparing flaky alpha alumina according to claim 1, characterized in that: in the step (1), the molten salt is one or more of sodium sulfate, sodium chloride, potassium sulfate and potassium chloride.
4. The method for preparing flaky alpha alumina according to claim 1, characterized in that: the molten salt in the step (1) has a mass 3-10 times that of the aluminum source.
5. The method for producing flaky alpha alumina according to claim 1, characterized in that: in the step (1), the aluminum source is aluminum hydroxide; the molten salt is one or two of sodium chloride and potassium chloride, and the mass ratio of the two molten salts is 1: 1.
6. The method for producing flaky alpha alumina according to claim 1, characterized in that: in the step (2), the adding amount of the aluminum fluoride is 2-9 wt% of the aluminum source.
7. The method for producing flaky alpha alumina according to claim 1, characterized in that: in the step (2), the adding amount of the aluminum fluoride is 4-6 wt% of the aluminum source.
8. The method for producing flaky alpha alumina according to claim 1, characterized in that: in the step (3), the mixture is heated to 750-900 ℃, the temperature is kept for 0.5-3h, and the heating rate is 5-10 ℃/min.
9. The method for producing flaky alpha alumina according to any one of claims 1 to 8, characterized in that: in the step (3), the temperature is heated to 750 ℃ and is preserved for 3h, or the temperature is preserved for 1h at 800 ℃ or the temperature is preserved for 0.5h at 900 ℃.
10. The flaky alpha alumina prepared by the method for preparing flaky alpha alumina according to any one of claims 1 to 9, wherein the flaky alpha alumina has an average radial particle size of 4 to 5 μm, a thickness of 150 to 250nm, and a ratio of the diameter to the thickness of 16 to 25.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115448341A (en) * | 2022-08-26 | 2022-12-09 | 广西大学 | Preparation method of flaky beta-alumina |
| CN117326579A (en) * | 2023-11-29 | 2024-01-02 | 化学与精细化工广东省实验室 | Method for preparing monodisperse hexagonal flaky alpha-alumina at ultralow temperature |
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| WO2009028887A2 (en) * | 2007-08-31 | 2009-03-05 | Jps Micro-Tech Co., Ltd. | Method of manufacturing flake aluminum oxide |
| CN101790495A (en) * | 2007-08-31 | 2010-07-28 | 株式会社Jps麦考泰克 | Utilize microwave to make the method for flake aluminum oxide |
| CN105645445A (en) * | 2016-01-06 | 2016-06-08 | 成都理工大学 | Platy-monocrystal alpha-aluminum oxide, and preparation method and application thereof |
| CN107140666A (en) * | 2017-05-15 | 2017-09-08 | 广西平果铝朗琨科技有限公司 | A kind of flaky alumina powder and preparation method thereof |
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| WO2009028887A2 (en) * | 2007-08-31 | 2009-03-05 | Jps Micro-Tech Co., Ltd. | Method of manufacturing flake aluminum oxide |
| CN101790495A (en) * | 2007-08-31 | 2010-07-28 | 株式会社Jps麦考泰克 | Utilize microwave to make the method for flake aluminum oxide |
| CN105645445A (en) * | 2016-01-06 | 2016-06-08 | 成都理工大学 | Platy-monocrystal alpha-aluminum oxide, and preparation method and application thereof |
| CN107140666A (en) * | 2017-05-15 | 2017-09-08 | 广西平果铝朗琨科技有限公司 | A kind of flaky alumina powder and preparation method thereof |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115448341A (en) * | 2022-08-26 | 2022-12-09 | 广西大学 | Preparation method of flaky beta-alumina |
| CN115448341B (en) * | 2022-08-26 | 2024-06-11 | 广西大学 | Preparation method of flaky beta alumina |
| CN117326579A (en) * | 2023-11-29 | 2024-01-02 | 化学与精细化工广东省实验室 | Method for preparing monodisperse hexagonal flaky alpha-alumina at ultralow temperature |
| CN117326579B (en) * | 2023-11-29 | 2024-03-08 | 化学与精细化工广东省实验室 | Method for preparing monodisperse hexagonal flaky alpha-alumina at ultralow temperature |
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