Preparation method of thermal insulation coating containing In2O3 and Al2O3 aerogel and capable of resisting temperature of 1000 DEG C

Abstract

The invention discloses a preparation method of an In2O3-coated Al2O3 aerogel-containing heat insulation coating capable of resisting the temperature of 1000 DEG C. The coating is prepared from an organic-inorganic compound adhesive, In2O3-coated Al2O3 aerogel, hollow ceramic microbeads, high-alumina ceramic fibers and an auxiliary agent, wherein the aerogel is prepared by combining an aluminum precursor sol-gel method with CO2 supercritical drying; and the agglomeration of the nanoparticles is inhibited through hydroxyethyl cellulose and epoxypropane. The adhesive adopts alkaline silica sol, sodium silicate and modified organic silicon emulsion to react step by step, and crosslinking is enhanced through hydro-thermal treatment. The components are prepared through high-speed dispersion according to a specific ratio, the heat conductivity coefficient of the obtained coating is as low as 0.038-0.047 W / (m.K), and the nano-pore structure is still kept at 1000 DEG C. Through the synergistic effect of the aerogel and the ceramic microbeads, the problems that a high-temperature heat-insulating coating is prone to cracking and poor in heat stability are solved, and the high-temperature heat-insulating coating is suitable for high-temperature environments such as industrial kilns and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and in particular relates to a method for preparing a 1000°C heat-insulating coating containing In2O3@Al2O3 aerogel. Background Art

[0002] With the development of industry and economic growth, energy conservation, emission reduction, and low-carbon environmental protection are increasingly demanded. New insulation materials are emerging in the industrial and construction sectors, and thermal insulation coatings are a representative example of these functional materials. These coatings are widely used due to their low thermal conductivity and excellent mechanical properties. Common insulation coatings can be categorized into three main types: organic, inorganic, and organic-inorganic composites. Among these, the insulation materials primarily used in industrial furnaces prioritize thermal insulation and high-temperature resistance (1000°C).

[0003] As we all know, the thermal conductivity of air is very low, with a thermal conductivity of 0.026 W / (m·K). Aerogel, a highly nanoporous material with a porosity exceeding 90%, typically exhibits structural characteristics such as high specific surface area, large pore volume, low density, and high porosity, while also possessing excellent thermal insulation properties. Silica (SiO2) aerogel and its derivatives have a long history and are the most widely studied aerogels. However, these aerogels decompose or sinter at relatively high temperatures.

[0004] Alumina (Al2O3) aerogels exhibit enhanced thermal stability, surpassing other oxide aerogels such as zirconia and titanium dioxide (TiO2). Furthermore, Al2O3 aerogels possess ultra-low thermal conductivity and excellent catalytic activity. Due to these fascinating properties, Al2O3 aerogels have enormous potential applications as high-temperature thermal insulators and catalysts. In2O3@Al2O3 aerogels can efficiently reflect infrared waves, effectively suppressing the radiative propagation of heat, further enhancing thermal insulation performance.

[0005] Therefore, combined with the ultra-low thermal conductivity and strong thermal stability of In2O3@Al2O3 aerogel, adding a large amount of In2O3@Al2O3 aerogel to high-temperature resistant coatings can greatly improve the thermal insulation and high-temperature resistance of the coatings. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing a 1000°C temperature-resistant thermal insulation coating containing In2O3@Al2O3 aerogel. In2O3@Al2O3 aerogel is applied to the thermal insulation coating to prepare a thermal insulation coating containing In2O3@Al2O3 aerogel. The thermal insulation coating has good high-temperature resistance and thermal insulation properties, solves the problem of poor high-temperature resistance and thermal insulation properties of the coating, has low production cost, and is a high-quality high-temperature resistant thermal insulation coating.

[0007] The present invention provides a 1000°C temperature-resistant thermal insulation coating containing In2O3@Al2O3 aerogel. The coating comprises, by weight, 100 parts of a compound adhesive, 20-35 parts of In2O3@Al2O3 aerogel, 25-40 parts of hollow ceramic microspheres, 10-15 parts of high-aluminum ceramic fibers, 2-4 parts of a film-forming agent, 0.5-1.5 parts of a leveling agent, 1.5-3 parts of a quick-drying agent, 0.5-1.5 parts of a thickener, and 0.5-1.5 parts of a wetting agent.

[0008] In the above scheme, the organic-inorganic composite adhesive comprises, by mass fraction, 30 to 45 parts of alkaline silica sol, 20 to 35 parts of sodium silicate solution, 20 to 30 parts of modified silicone emulsion, and 2 to 5 parts of silane coupling agent.

[0009] The present invention also provides a method for preparing a 1000°C heat-insulating coating containing In2O3@Al2O3 aerogel, which comprises the following steps: using In2O3@Al2O3 aerogel, an organic-inorganic composite adhesive, hollow ceramic microspheres, high-aluminum ceramic fibers, a film-forming agent, a leveling agent, a quick-drying agent, a thickener, a wetting agent, and deionized water, and performing high-speed dispersion and stirring: (1) The organic-inorganic composite adhesive comprises alkaline silica sol, sodium silicate solution, modified silicone emulsion, and silane coupling agent, which are calculated by mass fraction as follows: 30-45 parts of alkaline silica sol, 20-35 parts of sodium silicate solution, 20-30 parts of modified silicone emulsion, and 2-5 parts of silane coupling agent. At 50°C and under magnetic stirring, a silane coupling agent dilution solution (15%) is slowly added to the modified silicone emulsion to prepare reaction solution 1, and the reaction is carried out for 30 minutes; the alkaline silica sol is slowly added to the reaction solution 1 to prepare reaction solution 2, and the reaction is carried out for 30 minutes; the sodium silicate solution is then slowly added to the reaction solution 2 to prepare reaction solution 3, and the reaction is carried out for 60 minutes; finally, the reaction solution 3 is added to a hydrothermal reactor, and the reaction is continuously carried out at 115°C and a pressure of 1.3 MPa for 2 hours to obtain an organic-inorganic composite adhesive; (2) The In2O3@Al2O3 aerogel of the present invention is prepared by the following method: S1: Add AlCl3·6H2O to water, add nano-In2O3 powder, ultrasonically disperse for 10 min, and add ethanol solvent (EtOH) to prepare aluminum precursor solution A; S2: Hydroxyethyl cellulose and methyl cellulose are added to the aluminum precursor solution A. After stirring for 3 hours, a light yellow suspension B with a certain viscosity is formed. S3: Propylene oxide was added dropwise to suspension B at a uniform rate and stirred for 10 min to obtain In2O3@Al2O3 sol C; S4: The In2O3@Al2O3 sol C was allowed to stand at room temperature for 2 hours to gel and obtain In2O3@Al2O3 gel. The sol was then immersed in EtOH. The EtOH level should be approximately 2 cm above the upper surface of the In2O3@Al2O3 gel and replaced every 24 hours. This step was repeated 3-4 times to fully displace the residual water and organic matter in the gel, obtaining In2O3@Al2O3 wet gel. S5: The In2O3@Al2O3 wet gel is placed in a drying kettle of a multi-purpose supercritical test device, and an appropriate amount of anhydrous ethanol is added to completely submerge it, and CO2 supercritical drying is performed to obtain the In2O3@Al2O3 aerogel.

[0010] (3) Calculated by mass fraction: 100 parts of organic-inorganic composite adhesive, 20-35 parts of In2O3@Al2O3 aerogel, 25-40 parts of hollow ceramic microspheres, 10-15 parts of high-aluminum ceramic fiber, 2-4 parts of film-forming agent, 0.5-1.5 parts of leveling agent, 1.5-3 parts of quick-drying agent, 0.5-1.5 parts of thickener, and 0.5-1.5 parts of wetting agent. Add the above components in sequence and stir at high speed for 1-2 hours. Add deionized water to adjust the viscosity of the coating according to the requirements of scraping to obtain a gray viscous In2O3@Al2O3 aerogel heat-insulating coating resistant to 1000℃.

[0011] The aluminum precursor solution A of the present invention comprises, by mass fraction, 10 to 15 parts of AlCl3·6H2O, 20 to 25 parts of EtOH, 15 to 20 parts of water, and 1 to 3 parts of nano-In2O3 powder.

[0012] The suspension B of the present invention comprises, by mass fraction, 0.1 to 0.2 parts of hydroxyethyl cellulose and 0.4 to 0.8 parts of methyl cellulose.

[0013] The drop rate of propylene oxide in the suspension B of the present invention is 1-2 mL / min, and the mass fraction is 3-5 parts of propylene oxide.

[0014] The CO2 supercritical drying pressure of the present invention is 9-13 MPa, the drying temperature is 35-45°C, and the drying time is 4-7 hours.

[0015] Compared with the existing preparation method of high temperature resistant thermal insulation coating, the present invention has the following advantages and beneficial effects: (1) The present invention adds Al2O3 aerogel and dopes it with nano-In2O3 powder. Combining the optical performance advantages of Al2O3 and In2O3 powder, the infrared wavelength with obvious thermal effect can be reflected back. It has the high porosity and temperature resistance of nano-powder and aerogel. The nano-pores are smaller than the free path of air molecules, achieving high-performance thermal insulation. Compared with SiO2 aerogel, Al2O3 aerogel can withstand high temperatures and still maintains the nano-pore structure of aerogel at high temperatures without losing its thermal insulation performance.

[0016] (2) There are technical difficulties in doping Al2O3 aerogel with nano-In2O3 powder. In2O3 nanoparticles are prone to grain growth and agglomeration at high temperatures (>600°C), which reduces the doping effect. The present invention uses AlCl3·6H2O precursor solution and nano-In2O3 in step B1, and forms a uniform sol network through the gel induction effect of propylene oxide (PO) (step B3), thereby inhibiting the migration and agglomeration of In2O3 particles. At the same time, hydroxyethyl cellulose and methyl cellulose are added (step B2) to stabilize the dispersion of nanoparticles through the steric hindrance effect.

[0017] (3) The present invention uses a composite organic-inorganic adhesive. The silane coupling agent is fully hydrolyzed, and the hydrolysis product is silanol, which plays the role of coupling and anchoring the alkaline silica sol, sodium silicate and modified silicone emulsion. At high temperature, the multi-component silanol cross-condenses to form a reinforced network structure, thereby enhancing the bonding strength, adhesion and temperature resistance of the adhesive. The specific analysis is as follows: Difficulties: The poor interfacial compatibility between silicone emulsion and inorganic silica sol (such as sodium silicate) can easily lead to coating delamination or insufficient mechanical strength. This problem can be solved through the following key technologies: Step-by-step reaction and coupling agent modification: In steps A.1-A.3, the silane coupling agent is first pre-reacted with the silicone emulsion, and then alkaline silica sol and sodium silicate are gradually introduced to form a continuous network through chemical bonding (Si-O-Si).

[0018] Hydrothermal reaction to strengthen crosslinking: Step A.4 hydrothermal treatment at 115°C and 1.3 MPa promotes the polycondensation reaction of organic-inorganic components and improves the high-temperature weather resistance of the adhesive. (4) Synergistic effect of hollow ceramic microbeads and high-aluminum fibers. Improper mixing ratio of hollow ceramic microbeads and fibers will reduce the mechanical strength and thermal insulation performance of the coating. For this reason, the combination of hollow ceramic microbeads (25-40 parts) and high-aluminum ceramic fibers (10-15 parts) in the formula of the present invention utilizes the thermal insulation properties of microbeads (low thermal conductivity) and the reinforcing effect of fibers (anti-cracking) to form a multi-scale thermal insulation network. The silane coupling agent (2-5 parts) in the adhesive is used to enhance the bonding strength between the microbeads / fibers and the matrix, thereby reducing the interfacial thermal resistance.

[0019] (5) The thermal insulation coating prepared by using In2O3@Al2O3 aerogel is suitable for large-scale production, has simple construction conditions and excellent thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the SEM image of In2O3@Al2O3 aerogel; Figure 2 This is the SEM image of hollow ceramic microspheres; Figure 3 is the thermogravimetric (TG) graph of In2O3@Al2O3; Figure 4 It is a coating containing In2O3@Al2O3 aerogel with a temperature resistance of 1000℃ thermal insulation coating; Figure 5 is the thermal conductivity of Example 1; Figure 6 is the thermal conductivity of Example 2; Figure 7 is the thermal conductivity of Example 3; Figure 8 is the proportional thermal conductivity; Figure 9 This is a comparative table of embodiments. DETAILED DESCRIPTION

[0021] The following is a detailed description of the embodiments of the present invention. Although the present invention will be described and illustrated in conjunction with certain specific embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, modifications or equivalent substitutions of the present invention are intended to fall within the scope of the claims of the present invention.

[0022] In addition, in order to better illustrate the present invention, numerous specific details are given in the following detailed description. It will be understood by those skilled in the art that the present invention can also be implemented without these specific details.

[0023] The concept of the present invention is proposed based on actual production needs. To facilitate those skilled in the art to understand the technical concept of the present invention, the following further explanation is made: Example 1 This embodiment provides a method for preparing a 1000°C heat-insulating coating containing In2O3@Al2O3 aerogel, which comprises using In2O3@Al2O3 aerogel, an organic-inorganic composite adhesive, hollow ceramic microspheres, high-aluminum ceramic fibers, a film-forming agent, a leveling agent, a quick-drying agent, a thickener, a wetting agent, and deionized water, and performing high-speed dispersion and stirring. The method comprises the following steps: (1) The organic-inorganic composite adhesive comprises alkaline silica sol, sodium silicate solution, modified silicone emulsion, and silane coupling agent, which are calculated by mass fraction as follows: 40 parts of alkaline silica sol, 28 parts of sodium silicate solution, 30 parts of modified silicone emulsion, and 2 parts of silane coupling agent. At 50°C and under magnetic stirring, a silane coupling agent dilution (15%) is slowly added to the modified silicone emulsion to prepare reaction solution 1, and the reaction is carried out for 30 minutes; the alkaline silica sol is slowly added to the reaction solution 1 to prepare reaction solution 2, and the reaction is carried out for 30 minutes; then the sodium silicate solution is slowly added to the reaction solution 2 to prepare reaction solution 3, and the reaction is carried out for 60 minutes; finally, the reaction solution 3 is added to a hydrothermal reactor, and the reaction is continuously carried out at 115°C and a pressure of 1.3 MPa for 2 hours to obtain an organic-inorganic composite adhesive; (2) Reference Figure 1 This is the SEM image of In2O3@Al2O3 aerogel. Figure 3 3 is a thermogravimetric (TG) graph of In2O3@Al2O3. The In2O3@Al2O3 aerogel is prepared by the following method: S1: Add 10 parts of AlCl3·6H2O to 20 parts of water, add 1 part of nano-In2O3 powder, ultrasonically disperse for 10 minutes, and add 25 parts of ethanol solvent (EtOH) to prepare aluminum precursor solution A; S2: 0.1 parts of hydroxyethyl cellulose and 0.4 parts of methyl cellulose were added to the aluminum precursor solution A. After stirring for 3 hours, a light yellow suspension B with a certain viscosity was formed. S3: Add 3 parts of propylene oxide dropwise to suspension B at a constant rate (1-2 mL / min) and stir for 10 min to obtain In2O3@Al2O3 sol C; S4: The In2O3@Al2O3 sol C was allowed to stand at room temperature for 2 hours to gel and obtain In2O3@Al2O3 gel. The sol was then immersed in EtOH. The EtOH level should be approximately 2 cm above the upper surface of the In2O3@Al2O3 gel and replaced every 24 hours. This step was repeated 3-4 times to fully displace the residual water and organic matter in the gel, obtaining In2O3@Al2O3 wet gel. S5: The In2O3@Al2O3 wet gel was placed in a drying vessel of a multi-purpose supercritical test device, and an appropriate amount of anhydrous ethanol was added to completely submerge it. The In2O3@Al2O3 aerogel was obtained by supercritical CO2 drying at a pressure of 10 MPa, a drying temperature of 40°C, and a drying time of 5 h. By mass fraction: 100 parts of organic-inorganic composite adhesive, 20 parts of In2O3@Al2O3 aerogel, 39 parts of hollow ceramic microspheres ( Figure 2The above components are added in sequence, and the mixture is dispersed and stirred at high speed for 1 to 2 hours. Deionized water is added to adjust the viscosity of the coating according to the requirements of the scraping. A gray viscous In2O3@Al2O3 aerogel heat-insulating coating with a temperature resistance of 1000°C is obtained.

[0024] like Figure 4 The figure shows a coating containing In2O3@Al2O3 aerogel heat-resistant 1000℃ thermal insulation coating. The thermal conductivity (25℃) of the In2O3@Al2O3 aerogel heat-resistant 1000℃ thermal insulation coating is 0.047W / (m∙K). It dries naturally at room temperature without cracks. The maximum thermal conductivity is 1035℃. Figure 5 .

[0025] Example 2 This embodiment provides a method for preparing a 1000°C heat-insulating coating containing In2O3@Al2O3 aerogel, which comprises using In2O3@Al2O3 aerogel, an organic-inorganic composite adhesive, hollow ceramic microspheres, high-aluminum ceramic fibers, a film-forming agent, a leveling agent, a quick-drying agent, a thickener, a wetting agent, and deionized water, and performing high-speed dispersion and stirring. The method comprises the following steps: (1) The organic-inorganic composite adhesive comprises alkaline silica sol, sodium silicate solution, modified silicone emulsion, and silane coupling agent, which are calculated by mass fraction as follows: 36 parts of alkaline silica sol, 35 parts of sodium silicate solution, 26 parts of modified silicone emulsion, and 3 parts of silane coupling agent. At 50°C and under magnetic stirring, a silane coupling agent dilution (15%) is slowly added to the modified silicone emulsion to prepare reaction solution 1, and the reaction is carried out for 30 minutes; the alkaline silica sol is slowly added to the reaction solution 1 to prepare reaction solution 2, and the reaction is carried out for 30 minutes; then the sodium silicate solution is slowly added to the reaction solution 2 to prepare reaction solution 3, and the reaction is carried out for 60 minutes; finally, the reaction solution 3 is added to a hydrothermal reactor, and the reaction is continuously carried out at 115°C and a pressure of 1.3 MPa for 2 hours to obtain an organic-inorganic composite adhesive; (2) The In2O3@Al2O3 aerogel is prepared by the following method: S1: Add 13 parts of AlCl3·6H2O to 18 parts of water, add 3 parts of nano-In2O3 powder, ultrasonically disperse for 10 minutes, and add 22 parts of ethanol solvent (EtOH) to prepare aluminum precursor solution A; S2: 0.1 parts of hydroxyethyl cellulose and 0.6 parts of methyl cellulose were added to the aluminum precursor solution A. After stirring for 3 hours, a light yellow suspension B with a certain viscosity was formed. S3: 4 parts of propylene oxide were added dropwise to suspension B at a constant rate (1-2 mL / min) and stirred for 10 min to obtain In2O3@Al2O3 sol C; S4: The In2O3@Al2O3 sol C was allowed to stand at room temperature for 2 hours to gel and obtain In2O3@Al2O3 gel. The sol was then immersed in EtOH. The EtOH level should be approximately 2 cm above the upper surface of the In2O3@Al2O3 gel and replaced every 24 hours. This step was repeated 3-4 times to fully displace the residual water and organic matter in the gel, obtaining In2O3@Al2O3 wet gel. S5: The In2O3@Al2O3 wet gel was placed in a drying vessel of a multi-purpose supercritical test device, and an appropriate amount of anhydrous ethanol was added to completely submerge it. The In2O3@Al2O3 aerogel was obtained by supercritical CO2 drying at a pressure of 11 MPa, a drying temperature of 37°C, and a drying time of 6 h. Calculated by mass fraction: 100 parts of organic-inorganic composite adhesive, 31 parts of In2O3@Al2O3 aerogel, 25 parts of hollow ceramic microspheres, 10 parts of high-alumina ceramic fiber, 2 parts of film-forming agent, 0.5 parts of leveling agent, 1.5 parts of quick-drying agent, 0.5 parts of thickener, and 1.5 parts of wetting agent. Add the above components in sequence and stir at high speed for 1 to 2 hours. Add deionized water to adjust the viscosity of the coating according to the requirements of scraping to obtain a gray viscous In2O3@Al2O3 aerogel heat-insulating coating that is resistant to 1000°C.

[0026] The thermal conductivity of the In2O3@Al2O3 aerogel thermal insulation coating with a temperature resistance of 1000℃ is 0.038W / (m∙K) at 25℃. It dries naturally at room temperature without cracks and has a maximum temperature resistance of 1055℃. Figure 6 .

[0027] Example 3 This embodiment provides a method for preparing a 1000°C heat-insulating coating containing In2O3@Al2O3 aerogel, which comprises using In2O3@Al2O3 aerogel, an organic-inorganic composite adhesive, hollow ceramic microspheres, high-aluminum ceramic fibers, a film-forming agent, a leveling agent, a quick-drying agent, a thickener, a wetting agent, and deionized water, and performing high-speed dispersion and stirring. The method comprises the following steps: (1) The organic-inorganic composite adhesive comprises alkaline silica sol, sodium silicate solution, modified silicone emulsion, and silane coupling agent, which are calculated by mass fraction as follows: 44 parts of alkaline silica sol, 27 parts of sodium silicate solution, 24 parts of modified silicone emulsion, and 5 parts of silane coupling agent. At 50°C and under magnetic stirring, a silane coupling agent dilution (15%) is slowly added to the modified silicone emulsion to prepare reaction solution 1, and the reaction is carried out for 30 minutes; the alkaline silica sol is slowly added to the reaction solution 1 to prepare reaction solution 2, and the reaction is carried out for 30 minutes; then the sodium silicate solution is slowly added to the reaction solution 2 to prepare reaction solution 3, and the reaction is carried out for 60 minutes; finally, the reaction solution 3 is added to a hydrothermal reactor, and the reaction is continuously carried out at 115°C and a pressure of 1.3 MPa for 2 hours to obtain an organic-inorganic composite adhesive; (2) The In2O3@Al2O3 aerogel is prepared by the following method: S1: Add 15 parts of AlCl3·6H2O to 18 parts of water, add 2 parts of nano-In2O3 powder, ultrasonically disperse for 10 minutes, and add 23 parts of ethanol solvent (EtOH) to prepare aluminum precursor solution A; S2: 0.2 parts of hydroxyethyl cellulose and 0.8 parts of methyl cellulose were added to the aluminum precursor solution A. After stirring for 3 hours, a light yellow suspension B with a certain viscosity was formed. S3: Add 5 parts of propylene oxide dropwise to suspension B at a constant rate (1-2 mL / min) and stir for 10 min to obtain In2O3@Al2O3 sol C; S4: The In2O3@Al2O3 sol C was allowed to stand at room temperature for 2 hours to gel and obtain In2O3@Al2O3 gel. The sol was then immersed in EtOH. The EtOH level should be approximately 2 cm above the upper surface of the In2O3@Al2O3 gel and replaced every 24 hours. This step was repeated 3-4 times to fully displace the residual water and organic matter in the gel, obtaining In2O3@Al2O3 wet gel. S5: The In2O3@Al2O3 wet gel was placed in a drying vessel of a multi-purpose supercritical test device, and an appropriate amount of anhydrous ethanol was added to completely submerge it. The In2O3@Al2O3 aerogel was obtained by supercritical CO2 drying at a pressure of 12 MPa, a drying temperature of 45°C, and a drying time of 4 h. Calculated by mass fraction: 100 parts of organic-inorganic composite adhesive, 27 parts of In2O3@Al2O3 aerogel, 30 parts of hollow ceramic microspheres, 14 parts of high-alumina ceramic fiber, 3 parts of film-forming agent, 1.0 part of leveling agent, 3 parts of quick-drying agent, 1.0 part of thickener, and 1.0 part of wetting agent. Add the above components in sequence and stir at high speed for 1 to 2 hours. Add deionized water to adjust the viscosity of the coating according to the requirements of scraping to obtain a gray viscous In2O3@Al2O3 aerogel heat-insulating coating that is resistant to 1000°C.

[0028] The thermal conductivity of this thermal insulation coating (25℃) is 0.040W / (m∙K). It dries naturally at room temperature without cracks. The maximum temperature resistance is 1070℃. The thermal conductivity is shown in Figure 7 .

[0029] Example 4 Compared with Example 1, the preparation process of the organic-inorganic composite adhesive and In2O3@Al2O3 aerogel is the same, except that the coating formula of Example 1 is replaced with the coating formula of Example 2.

[0030] The thermal conductivity (25°C) of the In2O3@Al2O3 aerogel thermal insulation coating, which is resistant to 1000°C temperatures, is 0.042W / (m∙K). It dries naturally at room temperature without cracks and has a maximum temperature resistance of 1035°C.

[0031] Example 5 Compared with Example 3, the preparation process of the organic-inorganic composite adhesive and In2O3@Al2O3 aerogel is the same, except that the coating formula of Example 3 is replaced by the coating formula of Example 2.

[0032] The thermal conductivity (25°C) of the In2O3@Al2O3 aerogel thermal insulation coating, which is resistant to 1000°C temperatures, is 0.039W / (m∙K). It dries naturally at room temperature without cracks and has a maximum temperature resistance of 1070°C.

[0033] Example 6 Compared with Example 3, the preparation process of the organic-inorganic composite adhesive and In2O3@Al2O3 aerogel is the same, except that the coating formula of Example 3 is replaced with the coating formula of Example 2, and the amount of the organic-inorganic composite adhesive in the coating formula is changed to 75 parts.

[0034] The In2O3@Al2O3 aerogel thermal insulation coating with a temperature resistance of 1000℃ cracks when dried naturally at room temperature, and the thermal conductivity (25℃) and maximum temperature resistance cannot be measured.

[0035] Comparative Example This comparative example provides a method for preparing a heat-insulating coating resistant to 1000°C, comprising the steps of: using an organic-inorganic composite adhesive, hollow ceramic microspheres, high-aluminum ceramic fibers, a film-forming agent, a leveling agent, a quick-drying agent, a thickener, a wetting agent, and deionized water, and performing high-speed dispersion and stirring. The method comprises the following steps: (1) The organic-inorganic composite adhesive is the same as that in Example 2; (2) Calculated by mass fraction: 100 parts of organic-inorganic composite adhesive, 56 parts of hollow ceramic microspheres, 10 parts of high-aluminum ceramic fibers, 2 parts of film-forming agent, 0.5 parts of leveling agent, 1.5 parts of quick-drying agent, 0.5 parts of thickener, and 1.5 parts of wetting agent. Add the above components in sequence and stir at high speed for 1 to 2 hours. Add deionized water to adjust the viscosity of the coating according to the requirements of scraping to obtain a grayish-white viscous thermal insulation coating.

[0036] The thermal conductivity of this thermal insulation coating (25℃) is 0.058W / (m∙K). It dries naturally at room temperature without cracks. The maximum temperature resistance is 1055℃. The thermal conductivity is shown in Figure 8 .

[0037] For a detailed comparison of the above embodiments, see Figure 9 .

Claims

1. A thermal insulation coating containing In2O3@Al2O3 aerogel with a temperature resistance of 1000°C, characterized in that: By mass, 100 parts of compound adhesive are mixed with 20-35 parts of In2O3@Al2O3 aerogel, 25-40 parts of hollow ceramic microspheres, 10-15 parts of high-alumina ceramic fibers, 2-4 parts of film-forming agent, 0.5-1.5 parts of leveling agent, 1.5-3 parts of quick-drying agent, 0.5-1.5 parts of thickener, and 0.5-1.5 parts of wetting agent.

2. The thermal insulation coating containing In2O3@Al2O3 aerogel with a temperature resistance of 1000°C according to claim 1, characterized in that: The organic-inorganic composite adhesive comprises, by mass fraction, 30 to 45 parts of alkaline silica sol, 20 to 35 parts of sodium silicate solution, 20 to 30 parts of modified organic silicon emulsion, and 2 to 5 parts of silane coupling agent.

3. The thermal insulation coating containing In2O3@Al2O3 aerogel and having a temperature resistance of 1000°C according to claim 2, characterized in that: The steps of preparing the organic-inorganic composite adhesive include: Step 1.1: Add a 15% by mass concentration of a silane coupling agent dilution solution to the modified silicone emulsion, and stir under magnetic stirring at 50° C. for 30 minutes to obtain a reaction solution 1; Step A.2: Add alkaline silica sol to reaction solution 1 and continue the reaction for 30 minutes to obtain reaction solution 2; Step A.3: Add the sodium silicate solution to reaction solution 2 and continue the reaction for 60 minutes to obtain reaction solution 3; Step A.4: placing the reaction solution 3 in a hydrothermal reactor, and reacting at 115° C. and 1.3 MPa for 2 hours to obtain the organic-inorganic composite adhesive.

4. The thermal insulation coating containing In2O3@Al2O3 aerogel and having a temperature resistance of 1000°C according to claim 1, characterized in that: In2O3@Al2O3 aerogel was prepared by the following method: B1: Dissolve 10-15 parts of AlCl3·6H2O and 1-3 parts of nano-In2O3 powder in a mixture of 15-20 parts of water and 20-25 parts of ethanol, and obtain aluminum precursor solution A after ultrasonic dispersion; B2: Add 0.1-0.2 parts of hydroxyethyl cellulose and 0.4-0.8 parts of methyl cellulose to aluminum precursor solution A and stir for 3 hours to form suspension B; B3: Add 3-5 parts of propylene oxide dropwise to suspension B and stir for 10 minutes to obtain sol C; B4: Sol C was allowed to stand for 2 hours to gel, and then soaked and replaced with ethanol 3 to 4 times, each time for 24 hours, to obtain a wet gel; S5: The wet gel is subjected to supercritical CO2 drying at a pressure of 9 to 13 MPa and a temperature of 35 to 45°C for 4 to 7 hours to obtain In2O3@Al2O3 aerogel.

5. The method according to claim 3, characterized in that The drop rate of propylene oxide in suspension B is 1-2 mL / min.

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