Coal gangue-based alumina aerogel thermal insulation coating and preparation method thereof
By using coal gangue as the aluminum source to prepare alumina aerogel and modifying it with a silane coupling agent, the problem of poor bonding between alumina aerogel and water-based resin matrix was solved, realizing the preparation of low-cost and high-efficiency thermal insulation coatings suitable for fields such as construction and aerospace.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TAIYUAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-05-09
- Publication Date
- 2026-06-05
AI Technical Summary
Existing alumina aerogels have poor adhesion to water-based resin matrices, resulting in uneven film dispersion and high preparation costs, which limits their application in thermal insulation coatings.
Alumina aerogel was prepared using coal gangue as a low-cost aluminum source. It was modified with silane coupling agent KH550 and combined with an aqueous resin matrix. The composition ratio and preparation process were optimized to form an aerogel-resin matrix mixed slurry. Inorganic fillers and film-forming aids were added to prepare a coal gangue-based alumina aerogel thermal insulation coating.
It achieves efficient bonding between alumina aerogel and resin matrix, reduces preparation costs, improves the thermal insulation performance and mechanical strength of coatings, is suitable for large-scale production, and is convenient and environmentally friendly to apply.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of coating technology, and in particular to a coal gangue-based alumina aerogel thermal insulation coating and its preparation method. Background Technology
[0002] Existing thermal insulation coatings are mainly divided into two categories: organic and inorganic. Organic thermal insulation coatings such as polyurethane foam and polystyrene board are easily combustible at high temperatures and release toxic and harmful gases, posing safety hazards. Inorganic thermal insulation coatings such as rock wool and glass wool have generally poor thermal insulation effects and are heavy and inconvenient to construct. Alumina aerogel is a porous material with a nanoporous structure, possessing excellent characteristics such as low density, low thermal conductivity, and high porosity. Its nanopores can effectively limit air heat transfer, and its ultra-large specific surface area can increase the solid heat transfer path, making it an ideal thermal insulation material with broad application prospects in fields such as construction and aerospace. However, currently, the preparation of alumina aerogel mostly uses organic aluminum alkoxides as the aluminum source, resulting in high raw material costs and limiting its large-scale application.
[0003] Water-based coatings use water as a solvent, causing no environmental pollution. They are also convenient and cost-effective to apply, making them an important development direction for the coatings industry. Water-based resin matrices, in particular, are a preferred choice for thermal insulation coatings due to their excellent durability and water resistance, and the ability to form a dense and smooth film after curing. However, alumina aerogel particles have poor adhesion to organic resin matrices, and direct mixing can easily lead to uneven dispersion and film peeling, significantly reducing the performance of the prepared thermal insulation coating.
[0004] Therefore, how to efficiently combine alumina aerogel with an aqueous resin matrix while reducing the cost of aerogel preparation is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0005] The purpose of this invention is to provide a coal gangue-based alumina aerogel thermal insulation coating and its preparation method. Alumina aerogel is prepared using coal gangue as an inexpensive aluminum source. The bonding between the aerogel and the resin matrix is improved through a precise modification process. At the same time, the proportion of each component of the coating and the preparation process parameters are optimized to improve the thermal insulation performance of the coating. Moreover, the preparation process is simple and controllable, the raw materials are readily available, and it is suitable for large-scale production.
[0006] To achieve the above objectives, the present invention provides a coal gangue-based alumina aerogel thermal insulation coating, comprising the following components by weight percentage: 60-75% aerogel-resin matrix mixture, 20-35% inorganic filler, 1-2% dispersant, 1-2% wetting agent, and 3% film-forming aid; wherein the aerogel-resin matrix mixture is formed by mixing coal gangue-based alumina aerogel powder and resin matrix at a mass ratio of 1:5-8.
[0007] Preferably, the resin matrix is one of waterborne acrylic emulsion, waterborne epoxy resin, and waterborne styrene-acrylic emulsion.
[0008] Preferably, the inorganic filler is one of hollow glass microspheres, rutile titanium dioxide, or mica powder.
[0009] Preferably, the dispersant is sodium dodecyl sulfate, the wetting agent is an alkylphenol polyoxyethylene ether wetting agent, and the film-forming aid is dodecyl alcohol ester.
[0010] This invention also provides a method for preparing the above-mentioned coal gangue-based alumina aerogel thermal insulation coating, comprising the following steps: S1. Preparation of coal gangue-based alumina aerogel powder; S2. Using silane coupling agent KH550 as a modifier, coal gangue-based alumina aerogel powder was dispersed with modifier, dispersant and wetting agent in deionized water and stirred to prepare aerogel dispersion. S3. The aerogel dispersion is mixed with the resin matrix and dispersant to obtain an aerogel-resin matrix slurry. Inorganic filler is then added and mixed to obtain a mixture. S4. Add film-forming aid to the mixture and stir to obtain thermal insulation coating.
[0011] Preferably, step S1 specifically includes the following steps: S1-1. Using coal gangue as the aluminum source, aluminum is extracted by acid leaching after calcination to obtain an aluminum chloride solution; S1-2. Add anhydrous ethanol to aluminum chloride solution, stir, add propylene oxide, and let stand to obtain aluminum oxide gel. S1-3, Alumina gel is aged, modified twice, washed, dried, pulverized and sieved to obtain coal gangue-based alumina aerogel powder.
[0012] Preferably, the specific operation of step S1-1 is as follows: calcining 200-mesh coal gangue at 800℃ for 2 hours, and then extracting aluminum with 6mol / L hydrochloric acid at 120℃ to obtain an aluminum chloride solution.
[0013] Preferably, in steps S1-2, the molar ratio of aluminum to anhydrous ethanol is 1:16, and propylene oxide is added after stirring at 60°C for 2 hours, with the molar ratio of aluminum to propylene oxide being 1:9.
[0014] Preferably, in steps S1-3, the solvents used for aging and cleaning are all anhydrous ethanol; the modifier used for modification is prepared by mixing anhydrous ethanol and tetraethyl orthosilicate in a volume ratio of 1:2~8; the drying temperature is 60-120℃, the drying time is 24-36h, and the sieve used for sieving is 300 mesh.
[0015] Preferably, in step S2, the solid-liquid ratio of coal gangue-based alumina aerogel powder and silane coupling agent KH550 is 1g:0.5-1mL.
[0016] Therefore, the coal gangue-based alumina aerogel thermal insulation coating and its preparation method provided by the present invention have the following beneficial effects: (1) This invention innovatively uses coal gangue, an industrial solid waste, as an aluminum source to replace expensive organic aluminum alcohol salts in the preparation of alumina aerogel, which greatly reduces the cost of raw materials and realizes the resource utilization of solid waste, thus having both economic and environmental value.
[0017] (2) The present invention prepared coal gangue-based alumina aerogel powder by two modifications of anhydrous ethanol and tetraethyl orthosilicate, and then modified the surface of the aerogel powder with silane coupling agent KH550, which effectively improved the surface properties of the aerogel and solved the technical problems of poor bonding and uneven dispersion between the aerogel and the resin matrix.
[0018] (3) This invention uses aerogel as the core heat-insulating component, resin matrix as the film-forming carrier, inorganic fillers to assist in heat insulation and enhance coating performance, and other chemical additives to optimize dispersion, wetting, and film-forming effects. The components are precisely matched to achieve synergistic performance improvement. This results in a coating with a thermal conductivity as low as 0.11~0.14 W / (m·K), exhibiting outstanding heat insulation performance. At the same time, the coating hardness can reach 3H~5H, the adhesion is 4B, and there are no defects such as swelling, peeling, flaking, or blistering after soaking in 5% sulfuric acid solution and 7% sodium hydroxide solution for 7 days. It has good mechanical strength and acid and alkali resistance and chemical stability.
[0019] (4) The entire preparation process does not require special high-end equipment. The preparation process is simple and controllable, with good process repeatability, and can achieve large-scale industrial production. Moreover, the coating is a water-based system, which is environmentally friendly and pollution-free. It can be directly applied to various substrates such as metal, wood, and concrete, making construction convenient and applicable to a wide range of scenarios.
[0020] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation
[0021] This invention provides a coal gangue-based alumina aerogel thermal insulation coating, which, by weight percentage, consists of 60-75% aerogel-resin matrix mixed slurry, 20-35% inorganic filler, 1-2% dispersant, 1-2% wetting agent, and 3% film-forming aid.
[0022] Among them, the aerogel-resin matrix mixture is the core film-forming and heat-insulating system of the coating. It is made by mixing coal gangue-based alumina aerogel powder and resin matrix at a mass ratio of 1:5~8. The resin matrix can be selected from water-based acrylic emulsion, water-based epoxy resin, or water-based styrene-acrylic emulsion. All of them are water-based systems, which are environmentally friendly and have good compatibility with aerogel.
[0023] Inorganic fillers are auxiliary insulation and reinforcing components for coatings. One of the following can be selected: hollow glass microspheres, rutile titanium dioxide, and mica powder. These fillers can not only help improve the thermal insulation performance of coatings, but also enhance the density and mechanical strength of the coating film.
[0024] The dispersant is sodium dodecyl sulfate, which can effectively prevent aerogel powder and inorganic fillers from agglomerating in the system and improve dispersion uniformity; the wetting agent is alkylphenol polyoxyethylene ether wetting agent, which reduces the surface tension of the coating and improves the wettability and adhesion of the coating on various substrates; the film-forming aid is dodecyl alcohol ester, which can improve the film-forming properties of the resin matrix and make the coating film denser and more complete.
[0025] This invention also provides a method for preparing the above-mentioned coal gangue-based alumina aerogel thermal insulation coating, with clear process steps and precise and controllable parameters, specifically including the following steps: S1. Using inexpensive coal gangue as the aluminum source, coal gangue-based alumina aerogel powder is prepared through calcination, acid leaching, gelation, aging, modification, cleaning, drying, pulverization, and sieving. Specifically: S1-1. Calcine 200-mesh coal gangue at 800℃ for 2 hours to remove organic impurities and activate the aluminum source. Then, extract the aluminum with 6mol / L hydrochloric acid at 120℃ to convert the aluminum oxide in the coal gangue into aluminum chloride. After filtration, obtain an aluminum chloride solution.
[0026] S1-2. Add anhydrous ethanol to the aluminum chloride solution, controlling the molar ratio of aluminum to anhydrous ethanol to be 1:16. Stir at 60°C for 2 hours to ensure thorough mixing. Then add propylene oxide, controlling the molar ratio of aluminum to propylene oxide to be 1:9. After standing, aluminum oxide gel is obtained.
[0027] S1-3. The alumina gel is aged in anhydrous ethanol for 24-48 hours. After aging, it is transferred to a modification solution prepared by anhydrous ethanol and tetraethyl orthosilicate at a volume ratio of 1:2-8 for modification treatment. The modification is performed twice, each time for 12-24 hours. After modification, the residual modifier and impurities are removed by washing with anhydrous ethanol. Then, it is dried at 60-120℃ for 24-36 hours. The dried aerogel block is crushed and passed through a 300-mesh sieve to obtain coal gangue-based alumina aerogel powder.
[0028] S2. Using silane coupling agent KH550 as a modifier, coal gangue-based alumina aerogel powder, along with silane coupling agent KH550, a dispersant, and a wetting agent, were dispersed in deionized water and stirred at 1000 r / min for 3 hours to obtain an aerogel dispersion. The solid-liquid ratio of coal gangue-based alumina aerogel powder to silane coupling agent KH550 was 1 g: 0.5-1 mL. Silane coupling agent KH550 can modify the surface of the aerogel powder, improving its compatibility and bonding with the aqueous resin matrix.
[0029] S3. Add the aerogel dispersion, resin matrix, and dispersant together into a mixing device and mix at a high speed of 1000 r / min for 30 min to obtain an aerogel-resin matrix mixed slurry; then add inorganic filler to the mixed slurry and continue to mix at a high speed of 1000 r / min for 30 min to uniformly disperse the inorganic filler in the system to obtain a mixture.
[0030] S4. Keep the mixing equipment running, add the film-forming aid to the mixture, and continue mixing for 10 minutes to fully integrate the film-forming aid with the mixture, and finally obtain the coal gangue-based alumina aerogel thermal insulation coating.
[0031] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the invention should be considered equivalent substitutions and are included within the scope of protection of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the scope of protection of the invention.
[0032] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.
[0033] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.
[0034] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art, and the testing standards all use national or international standards commonly used in the field, without further explanation.
[0035] The water-based acrylic emulsion used in the following examples and comparative examples is grade E0504 acrylic emulsion.
[0036] Example 1 This embodiment provides a coal gangue-based alumina aerogel thermal insulation coating, the components of which by weight percentage are: 65% aerogel-resin matrix mixed slurry, 30% hollow glass microspheres, 1% sodium dodecyl sulfate, 1% dodecylphenol polyoxyethylene ether, and 3% dodecyl alcohol ester; wherein the aerogel-resin matrix mixed slurry is formed by mixing coal gangue-based alumina aerogel powder and aqueous acrylic emulsion at a mass ratio of 1:8.
[0037] The preparation method of the above-mentioned thermal insulation coating is as follows: S1. Take 200-mesh coal gangue, calcine at 800℃ for 2 hours, and extract aluminum by acid leaching with 6mol / L hydrochloric acid at 120℃ for 2 hours to obtain aluminum chloride solution; add anhydrous ethanol at a ratio of aluminum to anhydrous ethanol of 1:16 (molar ratio), stir at 60℃ for 2 hours, then add propylene oxide (aluminum to propylene oxide = 1:9, molar ratio) and let stand to obtain alumina gel; the alumina gel is aged in anhydrous ethanol for 48 hours, modified twice (24 hours each time) with a modification solution of anhydrous ethanol to tetraethyl orthosilicate of 1:5 (volume ratio), washed with anhydrous ethanol, dried at 60℃ and 80℃ for 6 hours respectively, and dried at 100℃ and 120℃ for 8 hours respectively, and then pulverized through a 300-mesh sieve to obtain coal gangue-based alumina aerogel powder.
[0038] S2. According to the solid-liquid ratio of coal gangue-based alumina aerogel powder: KH550 = 1g: 0.5mL, 3g of aerogel powder, 1.5mL of KH550, 1% of dispersant and 1% of wetting agent are dispersed in 40mL of deionized water and stirred at 1000r / min for 3h to obtain an aerogel dispersion.
[0039] S3. Stir the aerogel dispersion with the aqueous acrylic emulsion and 1% dispersant at 1000 r / min for 30 min to obtain an aerogel-resin matrix mixture. Add 30% hollow glass microspheres and continue stirring at 1000 r / min for 30 min to obtain a mixture.
[0040] S4. Add 3% dodecyl alcohol ester to the mixture and stir at 1000 r / min for 10 min to obtain coal gangue-based alumina aerogel thermal insulation coating.
[0041] Example 2 This embodiment provides a coal gangue-based alumina aerogel thermal insulation coating, the components of which by weight percentage are: 70% aerogel-resin matrix mixed slurry, 25% hollow glass microspheres, 1% sodium dodecyl sulfate, 1% dodecylphenol polyoxyethylene ether, and 3% dodecyl alcohol ester; wherein the aerogel-resin matrix mixed slurry is formed by mixing coal gangue-based alumina aerogel powder and aqueous acrylic emulsion at a mass ratio of 1:6.
[0042] The preparation method of the above-mentioned thermal insulation coating is as follows: S1 is the same as in Example 1.
[0043] S2. According to the solid-liquid ratio of coal gangue-based alumina aerogel powder: KH550 = 1g: 0.8mL, 4g of aerogel powder, 3.2mL of KH550, 1% dispersant, and 1% wetting agent are dispersed in 60mL of deionized water and stirred at 1000r / min for 3h to obtain an aerogel dispersion.
[0044] S3. Stir the aerogel dispersion with the aqueous acrylic emulsion and 1% dispersant at 1000r / min for 30min to obtain an aerogel-resin matrix mixture. Add 25% hollow glass microspheres and continue stirring at 1000r / min for 30min to obtain a mixture.
[0045] S4. Add 3% dodecyl alcohol ester to the mixture and stir at 1000 r / min for 10 min to obtain coal gangue-based alumina aerogel thermal insulation coating.
[0046] Example 3 This embodiment provides a coal gangue-based alumina aerogel thermal insulation coating, the components of which by weight percentage are: 75% aerogel-resin matrix mixed slurry, 20% hollow glass microspheres, 1% sodium dodecyl sulfate, 1% dodecylphenol polyoxyethylene ether, and 3% dodecyl alcohol ester; wherein the aerogel-resin matrix mixed slurry is formed by mixing coal gangue-based alumina aerogel powder and water-based acrylic emulsion at a mass ratio of 1:5.
[0047] The preparation method of the above-mentioned thermal insulation coating is as follows: S1 is the same as in Example 1.
[0048] S2. According to the solid-liquid ratio of coal gangue-based alumina aerogel powder: aerogel powder: KH550 = 1g: 1mL, 5g of aerogel powder, 5mL of KH550, 1% of dispersant, and 1% of wetting agent are dispersed in 75mL of deionized water and stirred at 1000r / min for 3h to obtain an aerogel dispersion.
[0049] S3. Stir the aerogel dispersion with the aqueous acrylic emulsion and 1% dispersant at 1000r / min for 30min to obtain an aerogel-resin matrix mixture. Add 20% hollow glass microspheres and continue stirring at 1000r / min for 30min to obtain a mixture.
[0050] S4. Add 3% dodecyl alcohol ester to the mixture and stir at 1000 r / min for 10 min to obtain coal gangue-based alumina aerogel thermal insulation coating.
[0051] Comparative Example This comparative example provides a thermal insulation material without the addition of coal gangue-based alumina aerogel powder, the components of which by weight percentage are: 45% aqueous acrylic emulsion, 50% hollow glass microspheres, 1% sodium dodecyl sulfate, 1% dodecylphenol polyoxyethylene ether, and 3% dodecyl alcohol ester.
[0052] The preparation method of the above materials is as follows: S1. Using water-based acrylic emulsion as the base, add sodium dodecyl sulfate and alkylphenol polyoxyethylene ether wetting agent, mix and add to a high-speed disperser, and stir at a speed of 1000 r / min for 30 min.
[0053] S2. Add hollow glass microspheres and continue stirring at 1000 r / min for 30 min to obtain a mixed slurry.
[0054] (3) Continue stirring the mixed slurry, add dodecyl alcohol ester at the same time, and continue stirring at 1000r / min for 10min to obtain the thermal insulation coating.
[0055] The alumina aerogel-modified thermal insulation coatings of Examples 1-3 above were compared with the thermal insulation coatings without alumina aerogel in the comparative example. Specific tests included: hardness, adhesion, acid and alkali resistance, and thermal conductivity.
[0056] The testing standards are: Hardness: According to GB / T 6739 "Determination of Hardness of Paints and Varnishes by Pencil Method", the pencil hardness method is used to test the hardness of the paint film. Different hardness grades of pencils are selected and the paint film surface is scratched at a specified angle and with a specified force. The hardness grade of the paint film is determined by observing whether the paint film is scratched.
[0057] Adhesion: According to GB / T 9286 "Cross-cut test of paint and varnish film", the cross-cut test is adopted. The cross-cut tester is used to draw squares at specified intervals on the coating surface, and the degree of paint film peeling off within the squares is observed to determine the adhesion level.
[0058] Acid resistance: According to GB / T 9274 "Determination of resistance to liquid media for paints and varnishes", the paint film sample is completely immersed in a 5% sulfuric acid (H2SO4) aqueous solution and left to stand at room temperature for 7 days. After taking it out, observe whether there are defects such as expansion, peeling, flaking, or blistering on the sample surface. If there are no such defects, the acid resistance is qualified.
[0059] Alkali resistance: According to GB / T 9274 "Determination of resistance to liquid media for paints and varnishes", the paint film sample is completely immersed in a 7% sodium hydroxide (NaOH) aqueous solution and left to stand at room temperature for 7 days. After taking it out, observe whether there are defects such as expansion, peeling, flaking, or blistering on the surface of the sample. If there are no such defects, the alkali resistance is qualified.
[0060] Thermal conductivity: According to GB / T 10295 "Determination of steady-state thermal resistance and related properties of thermal insulation materials by heat flow meter method", the coating film sample of the coating is tested by a thermal conductivity meter and the thermal conductivity value is read. The unit is W / (m·K).
[0061] The comparison results are shown in Table 1.
[0062] Table 1: Coating Performance Test Results
[0063] As can be seen from the comparison of the test results of Examples 1-3 and the comparative examples in Table 1, the coal gangue-based alumina aerogel thermal insulation coating prepared by this invention is far superior to conventional thermal insulation coatings in terms of thermal conductivity and hardness. Its thermal insulation performance and mechanical strength are significantly improved, while maintaining good adhesion and acid and alkali resistance. This indicates that the formulation and preparation method provided by this invention successfully introduces coal gangue-based alumina aerogel into an aqueous coating system, allowing it to fully exert its reinforcing and insulating functions.
[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A coal gangue-based alumina aerogel thermal insulation coating, characterized in that, By weight percentage, it includes the following components: The aerogel-resin matrix mixture comprises 60-75% aerogel-resin matrix, 20-35% inorganic filler, 1-2% dispersant, 1-2% wetting agent, and 3% film-forming aid; wherein the aerogel-resin matrix mixture is made by mixing coal gangue-based alumina aerogel powder and resin matrix at a mass ratio of 1:5-8.
2. The coal gangue-based alumina aerogel thermal insulation coating according to claim 1, characterized in that, The resin matrix is one of waterborne acrylic emulsion, waterborne epoxy resin, or waterborne styrene-acrylic emulsion.
3. The coal gangue-based alumina aerogel thermal insulation coating according to claim 1, characterized in that, The inorganic filler is one of the following: hollow glass microspheres, rutile titanium dioxide, and mica powder.
4. The coal gangue-based alumina aerogel thermal insulation coating according to claim 1, characterized in that, The dispersant is sodium dodecyl sulfate, the wetting agent is alkylphenol polyoxyethylene ether wetting agent, and the film-forming aid is dodecyl alcohol ester.
5. A method for preparing a coal gangue-based alumina aerogel thermal insulation coating as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Preparation of coal gangue-based alumina aerogel powder; S2. Using silane coupling agent KH550 as a modifier, coal gangue-based alumina aerogel powder was dispersed with modifier, dispersant and wetting agent in deionized water and stirred to prepare aerogel dispersion. S3. The aerogel dispersion is mixed with the resin matrix and dispersant to obtain an aerogel-resin matrix slurry. Inorganic filler is then added and mixed to obtain a mixture. S4. Add film-forming aid to the mixture and stir to obtain thermal insulation coating.
6. The preparation method of a coal gangue-based alumina aerogel thermal insulation coating according to claim 5, characterized in that, Step S1 specifically includes the following steps: S1-1. Using coal gangue as the aluminum source, aluminum is extracted by acid leaching after calcination to obtain an aluminum chloride solution; S1-2. Add anhydrous ethanol to aluminum chloride solution, stir, add propylene oxide, and let stand to obtain aluminum oxide gel. S1-3, Alumina gel is aged, modified twice, washed, dried, pulverized and sieved to obtain coal gangue-based alumina aerogel powder.
7. The preparation method of a coal gangue-based alumina aerogel thermal insulation coating according to claim 6, characterized in that, The specific operation of step S1-1 is as follows: calcining 200-mesh coal gangue at 800℃ for 2 hours, and then leaching aluminum with 6mol / L hydrochloric acid at 120℃ to obtain an aluminum chloride solution.
8. The preparation method of a coal gangue-based alumina aerogel thermal insulation coating according to claim 6, characterized in that, In steps S1-2, the molar ratio of aluminum to anhydrous ethanol is 1:
16. After stirring at 60°C for 2 hours, propylene oxide is added, and the molar ratio of aluminum to propylene oxide is 1:
9.
9. The preparation method of a coal gangue-based alumina aerogel thermal insulation coating according to claim 6, characterized in that, In steps S1-3, the solvent used for aging and cleaning is anhydrous ethanol; the modifier used for modification is prepared by mixing anhydrous ethanol and tetraethyl orthosilicate in a volume ratio of 1:2~8; the drying temperature is 60-120℃, the drying time is 24-36h, and the sieve used for sieving is 300 mesh.
10. The preparation method of a coal gangue-based alumina aerogel thermal insulation coating according to claim 5, characterized in that, In step S2, the solid-liquid ratio of coal gangue-based alumina aerogel powder and silane coupling agent KH550 is 1g:0.5-1mL.