SiO2-based composite high-temperature aerogel, preparation method thereof and high-temperature-resistant aerogel heat insulation coating

Abstract

According to the SiO2-based composite high-temperature aerogel, the preparation method thereof and the high-temperature-resistant aerogel heat insulation coating, from the perspective of improving the high temperature resistance and the surface adjustability of aerogel by a one-step method, an atomic vapor deposition method is adopted to prepare a SiO2-based composite high-temperature aerogel material with controllable surface characteristics; and an industrial thermal insulation coating product for the steam pipeline is developed by taking the coating as a thermal insulation filler. The high-temperature-resistant aerogel heat insulation coating can be used for a long time in an environment of 350 + / -50 DEG C, has efficient high-temperature heat insulation performance, and is high in adhesive force and easy to construct.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal insulation materials, and specifically relates to a SiO2-based composite high-temperature aerogel and a preparation method thereof, and a high-temperature resistant aerogel thermal insulation coating. Background Art

[0002] In recent years, with the increasing calls for energy conservation and emission reduction around the world, the insulation demand for steam pipes, as an important way of transporting heat in industrial production, has become increasingly prominent. At the same time, there are many problems with the performance of traditional insulation materials in high temperature environments, such as poor insulation effect and easy aging, forcing people to seek new insulation materials with high performance and suitable for high temperature environments. In this context, aerogel coatings, as a new building material with ultra-low thermal conductivity and excellent insulation performance, have attracted much attention.

[0003] Aerogel coatings can improve the thermal insulation effect of steam pipes, effectively reduce energy loss and carbon emissions, and reduce operating costs, which is in line with the concept of sustainable development. They can also maintain a stable thermal insulation effect in a high-temperature steam environment, thereby improving steam transmission efficiency. Therefore, the development of a high-temperature aerogel coating for steam pipe insulation is of great significance and is conducive to promoting the green and sustainable development of industrial production.

[0004] Since the development of high-temperature aerogel coatings, there are still two major problems that need to be solved urgently. One is the compatibility of the use temperature range of aerogel coatings with the emulsion matrix and aerogel material types, and the other is the compatibility of the coating emulsion matrix with the surface characteristics of aerogels. Because each aerogel material preparation manufacturer has different processes, the aerogel modification effect varies, which seriously restricts the preparation and production of downstream aerogel coatings; at the same time, the aerogel front-end material party is out of touch with the coating preparation process, resulting in the coating party mostly using a re-modification method to prepare water-based aerogel coating products. The process is relatively complicated and there are certain problems with product quality control.

[0005] Based on the above reasons, this application is filed. Summary of the invention

[0006] Based on the above reasons, in view of the problems or defects existing in the prior art, the purpose of the present invention is to provide a SiO2-based composite high-temperature aerogel and a preparation method thereof, and a high-temperature resistant aerogel thermal insulation coating, so as to solve or at least partially solve the above-mentioned technical defects existing in the prior art: the present invention uses a core-shell structured SiO2-based composite high-temperature aerogel with controllable surface properties as an insulating filler to effectively improve the compatibility problem between the aqueous emulsion matrix and the aerogel material, and according to the application temperature range of the steam pipeline, uses micro-composite TiO2, ZrO2 and other shell materials to inhibit the conduction of infrared high-temperature radiation, and prepares a high-temperature resistant SiO2-based composite aerogel for aqueous emulsion in one step, thereby developing a flame-retardant, high-temperature resistant, thermal insulating aerogel coating.

[0007] In order to achieve the above first object of the present invention, the technical solution adopted by the present invention is as follows:

[0008] A SiO2-based composite high-temperature aerogel, specifically any one of SiO2@TiO2, SiO2@ZrO2 or SiO2@Al2O3.

[0009] Furthermore, in some embodiments, the SiO2-based composite high-temperature aerogel is preferably a SiO2-based composite high-temperature aerogel powder, the aerogel powder has a particle size of 50 to 80 μm, an average thermal conductivity of 0.065 to 0.085 W / (mk) at 500°C, and a hydrophobic angle of 110 to 130°.

[0010] The second object of the present invention is to provide a method for preparing the above-mentioned SiO2-based composite high-temperature aerogel, the steps of which are as follows:

[0011] Deionized water is added to the titanium source, zirconium source or aluminum source, and the mixture is mixed evenly. The obtained mixed solution is deposited on the surface of the SiO2 aerogel by atomic vapor deposition to obtain the SiO2-based composite high-temperature aerogel.

[0012] Furthermore, in some embodiments, the titanium source is tetrakisdimethylaminotitanium; the zirconium source is tetrakisdimethylaminozirconium; and the aluminum source is trimethylaluminum.

[0013] Specifically, in some embodiments, the surface morphology of the aerogel and the amount of particle deposition can be controlled by adjusting the number of deposition cycles, thereby achieving controllable surface properties of the aerogel.

[0014] Furthermore, in some embodiments, the SiO2 aerogel is prepared by the following method, the steps are as follows:

[0015] (1) gradually adding a dilute hydrochloric acid solution to the silicon source solution, controlling the pH value between 3 and 4, stirring until gelation occurs and then stopping the acid addition, then adding an ammonia solution to adjust the pH value of the system to 6.5 to 8, then heating to 55 to 65° C. and aging for 100 minutes to obtain SiO2 wet gel;

[0016] (2) adding a mixed solution of tetraethyl orthosilicate, anhydrous ethanol and deionized water to the SiO2 wet gel, placing the resulting reaction solution at 55 to 65° C. for solvent replacement for 12 to 48 hours, and washing the resulting product with anhydrous ethanol until it is neutral to obtain an aged gel;

[0017] (3) adding a hexamethyldisilazane-ethanol mixed solution to the aged gel at 55-65° C. to carry out a surface modification reaction for 12-48 hours; after the reaction, subjecting the obtained alcohol gel to supercritical drying to obtain SiO2 aerogel.

[0018] Furthermore, in some embodiments, the silicon source in step (1) is any one of methyltriethoxysilane, ethyl orthosilicate, propyl orthosilicate, sodium silicate, silica sol, etc.

[0019] Furthermore, in some embodiments, the concentration of the dilute hydrochloric acid solution in step (1) is 0.5-1.0 mol / L.

[0020] Furthermore, in some embodiments, the thermal aging time in step (1) is 100 minutes.

[0021] Furthermore, in some embodiments, the molar ratio of tetraethyl orthosilicate, anhydrous ethanol and deionized water in the mixed solution of step (2) is 1:4:6.

[0022] Furthermore, in some embodiments, the volume ratio of the SiO2 wet gel to the mixed solution in step (2) is 1:1.

[0023] Furthermore, in some embodiments, the hexamethyldisilazane-ethanol mixed solution in step (3) consists of hexamethyldisilazane and anhydrous ethanol, and the molar ratio of hexamethyldisilazane to anhydrous ethanol is 1 to 2:1.

[0024] Furthermore, in some embodiments, the supercritical drying process in step (3) is as follows:

[0025] The alcohol gel is placed in a supercritical ethanol kettle, anhydrous ethanol is added, the kettle is sealed and dried after being purged with nitrogen, the temperature is raised to 250-270°C, and the pressure is maintained at 13-15MPa for 4-6h. After returning to normal pressure and purging with nitrogen for 10min, the kettle can be opened and taken out after cooling to room temperature to obtain the SiO2 aerogel.

[0026] The third object of the present invention is to provide a SiO2-based composite high-temperature aerogel slurry, which is composed of a dispersant, a wetting agent, deionized water and a SiO2-based composite high-temperature aerogel, wherein: the SiO2-based composite high-temperature aerogel is the SiO2-based composite high-temperature aerogel prepared by the method described above in the present invention.

[0027] Furthermore, in some embodiments, the dispersant is one or more of carboxylates, sulfate esters, ammonium polyacrylates, and the like.

[0028] Furthermore, in some embodiments, the wetting agent is one or more of sodium dodecyl sulfate, polyvinyl alcohol, sodium dodecylbenzene sulfonate, polyether-modified polydimethylsiloxane, and the like.

[0029] Furthermore, in some embodiments, the mass ratio of the total mass of the wetting agent and the dispersant to the mass of the aerogel is 0.05 to 0.5:1.

[0030] Furthermore, in some embodiments, the mass fraction of the SiO2-based composite high-temperature aerogel slurry is 30-50wt%.

[0031] The fourth object of the present invention is to provide a method for preparing the above-mentioned SiO2-based composite high-temperature aerogel slurry, the steps of which are as follows: add a dispersant and a wetting agent into deionized water according to a ratio, stir evenly, then add SiO2-based composite high-temperature aerogel powder and disperse evenly at high speed.

[0032] A fifth object of the present invention is to provide a high temperature resistant aerogel thermal insulation coating, comprising the following raw materials in parts by weight:

[0033]

[0034]

[0035] Wherein: the aerogel slurry is the SiO2-based composite high-temperature aerogel slurry described above in the present invention.

[0036] Furthermore, in some embodiments, the ceramic microspheres are hollow silicon-aluminum-based ceramic microspheres with a compressive strength of 4000-6000 kg / cm 2 The thermal conductivity is 0.07~0.12W / (mk) and the heat resistance temperature can reach 1000℃.

[0037] Furthermore, in some embodiments, the film-forming emulsion is a mixture of an elastic acrylic emulsion and an organic silicone resin emulsion, the solid content is 50-60%, and the weight ratio of the elastic acrylic emulsion to the organic silicone resin emulsion is 0.35-0.60.

[0038] Furthermore, in some embodiments, the fiber is one or more of high silica fiber, quartz fiber, mullite fiber, and aluminum silicate fiber.

[0039] Further, in some embodiments, the flame retardant is one or more of magnesium hydroxide, ammonium polyphosphate, aluminum hydroxide, tributyl phosphate, and zinc borate;

[0040] Furthermore, in some embodiments, the auxiliary agent is one or more of benzyl alcohol, propylene glycol, ethylene glycol butyl ether, propylene glycol phenyl ether, dodecyl alcohol ester, and alcohol ester-12.

[0041] Furthermore, in some embodiments, the defoaming agent is one or more of a polysiloxane defoaming agent, a fatty acid defoaming agent, a polyacrylate defoaming agent, and a polyether defoaming agent.

[0042] The sixth object of the present invention is to provide a method for preparing the above-mentioned high-temperature resistant aerogel thermal insulation coating, the steps of which are as follows: deionized water, additives, defoaming agents, flame retardants, and film-forming emulsions are added to a dispersion kettle in proportion, and stirred and dispersed evenly; then SiO2-based composite high-temperature aerogel slurry, ceramic microbeads and fibers are added to the resulting mixed liquid in sequence, and stirring and dispersing is continued to be evenly obtained to obtain the high-temperature resistant aerogel thermal insulation coating.

[0043] Compared with the prior art, the present invention has the following technical effects:

[0044] (1) Compared with the doping methods of ultrasonic dispersion or mechanical stirring, the SiO2-based composite high-temperature aerogel atomic layer vapor deposition method provided by the present invention can deposit TiO 2、 ZrO 2、 The Al2O3 particle infrared sunshade is introduced into the surface of the aerogel, which greatly improves the uniformity and significantly increases the extinction coefficient. It has a more excellent infrared sunshade ability, can effectively reduce the high-temperature radiation and heat conduction of the material, and improve its high-temperature thermal insulation performance.

[0045] (2) The present invention adopts atomic vapor deposition method to prepare high temperature resistant SiO2-based composite aerogel material, and adjusts the hydrophilic and hydrophobic characteristics of the aerogel surface by controlling the number of cycles, so that the contact angle of the aerogel material can be controlled in the range of 0 to 180°, thereby having good surface adjustability, effectively solving the compatibility problem between the subsequent aqueous emulsion matrix and the aerogel material, so that the aerogel can be evenly dispersed in the emulsion system and maintain an excellent low thermal conductivity, which greatly reduces the production difficulty of high temperature aerogel coatings and can be applied on a large scale.

[0046] (3) The high temperature resistant SiO2-based composite aerogel powder used in the present invention can reflect near-infrared rays back into the steam pipeline at a high degree, can be used for a long time in an environment of 350±50°C, has high efficient high temperature insulation performance, strong adhesion, and is easy to construct, providing a new way for steam pipeline insulation. DETAILED DESCRIPTION

[0047] The present invention proposes a SiO2-based composite high-temperature aerogel and a preparation method thereof, and a high-temperature aerogel insulation coating. From the perspective of improving the high-temperature resistance and surface adjustability of aerogel in one step, an atomic vapor deposition method is used to prepare a SiO2-based composite high-temperature aerogel material with controllable surface properties, and an industrial thermal insulation coating product for steam pipes is developed using the aerogel as an insulation filler. The high-temperature aerogel insulation coating in the present invention can be used for a long time in an environment of 350±50℃, has high-efficiency high-temperature insulation performance, strong adhesion, and is easy to construct.

[0048] The present invention is further described in detail below through implementation cases. The equipment and raw materials used in the present invention can be purchased from the market or are commonly used in the art. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0049] Example 1

[0050] This embodiment first provides a SiO2-based composite high-temperature aerogel powder, specifically SiO2@TiO2 aerogel powder; the particle size of the SiO2@TiO2 aerogel powder is 50-80 μm, the average thermal conductivity at 500°C is 0.072 W / (mk), and the hydrophobic angle is 95-110°.

[0051] The SiO2-based composite high-temperature aerogel powder described in this embodiment is prepared by the following method, and the steps are as follows:

[0052] Weigh a certain amount of tetraethyl orthosilicate, gradually add 1.0 mol / L dilute hydrochloric acid solution, control the pH at about 3.0, stir for 30 minutes, stop adding acid after gelation occurs, then add 1 mol / L ammonia solution to adjust the pH value of the system to alkaline 6.5, then heat to 55°C and age for 100 minutes; add an equal volume of a mixed solution composed of tetraethyl orthosilicate, anhydrous ethanol and deionized water to the SiO2 wet gel, the molar ratio of tetraethyl orthosilicate, anhydrous ethanol and deionized water in the mixed solution is 1:1 :4:6; the obtained reaction solution was placed at 55°C for solvent replacement for 12 hours, and the aged gel was washed with anhydrous ethanol until neutral; at 55°C, a hexamethyldisilazane-ethanol mixed solution was added for surface modification, wherein the hexamethyldisilazane-ethanol mixed solution consisted of hexamethyldisilazane and anhydrous ethanol, and the molar ratio of hexamethyldisilazane to anhydrous ethanol was 2:1, and the surface modification reaction was carried out for 12 hours; after the reaction, the obtained alcohol gel was placed in a supercritical ethanol kettle, anhydrous ethanol was added, and nitrogen After purging, the drying kettle is sealed, the temperature is raised to 250°C, maintained at a pressure of 13MPa for 4h, and after returning to normal pressure, it is purged with nitrogen for 10min, and then cooled to room temperature and the kettle can be opened to take out the hydrophobic SiO2 aerogel; the SiO2 aerogel is placed in a reactor as a core material, and the titanium source tetrakisdimethylaminotitanium is introduced into the reactor in gaseous form to react chemically with the surface of the SiO2 aerogel to form a layer of titanium compounds, and then the reactor is purged with nitrogen to remove unreacted titanium sources and by-products, and then oxygen source water vapor is introduced to react with the previously formed titanium compound to generate a TiO2 shell layer, and the reactor is also purged with nitrogen to remove unreacted oxygen sources and by-products, and the above pulse and purge steps are repeated 25 times until the desired number of TiO2 particle layers is reached, and the film thickness is about 2.5nm to prepare a SiO2-based composite high-temperature aerogel with a small amount of TiO2 particles deposited; finally, the aerogel is fully mechanically ground into micro-nano particles to obtain SiO2@TiO2 aerogel powder, which is subsequently used for coating preparation.

[0053] The present embodiment also provides a SiO2@TiO2 aerogel slurry, in which the mass fraction of aerogel is 40wt%; the slurry is composed of a dispersant, a wetting agent, deionized water and SiO2@TiO2 aerogel powder, wherein: the SiO2@TiO2 aerogel powder is the SiO2@TiO2 aerogel powder prepared by the method described above in the present embodiment; the dispersant is a carboxylate; the wetting agent is sodium dodecyl sulfate; the mass ratio of the total mass of the dispersant and the wetting agent to the SiO2@TiO2 aerogel powder is 0.08.

[0054] The preparation method of the SiO2@TiO2 aerogel slurry is as follows: add the dispersant and the wetting agent into deionized water according to the ratio, stir evenly, then add the SiO2@TiO2 aerogel powder, and disperse at high speed for 1 hour.

[0055] This embodiment also provides a high temperature resistant aerogel insulation coating composed of the following components:

[0056] 20 parts by mass of deionized water, 21.2 parts by mass of SiO2@TiO2 aerogel slurry, 15 parts by mass of ceramic microbeads, 40 parts by mass of film-forming emulsion, 0.5 parts by mass of fiber, 0.2 parts by mass of flame retardant, 3 parts by mass of auxiliary agent, and 0.1 parts by mass of defoaming agent;

[0057] The SiO2@TiO2 aerogel slurry is the SiO2@TiO2 aerogel slurry prepared by the method described above in this embodiment; the ceramic microspheres are hollow silicon-aluminum-based ceramic microspheres with a compressive strength of 4000-6000 kg / cm 2 , thermal conductivity is 0.07-0.12W / (mk), and heat resistance temperature can reach 1000°C; the film-forming emulsion is a mixture of elastic acrylic emulsion and silicone resin emulsion, with a solid content of 50-60%, and the weight ratio of the elastic acrylic emulsion to the silicone resin emulsion is 0.35; the fiber is quartz fiber; the flame retardant is magnesium hydroxide; the auxiliary agent is propylene glycol; the defoaming agent is a polysiloxane defoaming agent.

[0058] The preparation method of the high temperature resistant aerogel thermal insulation coating described above in this embodiment is as follows: deionized water, additives, defoaming agents, flame retardants, and film-forming emulsions are added to a dispersion kettle according to a ratio, stirred evenly, and dispersed at 200r / min for 15min; aerogel slurry, ceramic microbeads, and fibers are added to the mixed liquid in sequence, and dispersed at 800r / min for 1h until the mixture is evenly dispersed into a slurry-like coating to obtain the high temperature resistant aerogel thermal insulation coating.

[0059] Example 2

[0060] This embodiment first provides a SiO2-based composite high-temperature aerogel powder, specifically SiO2@Al2O3 aerogel powder; the particle size of the SiO2@Al2O3 aerogel powder is 50-80 μm, the hydrophobic angle reaches 110-120°, and the average thermal conductivity at 500°C is 0.085 W / (mk).

[0061] The SiO2-based composite high-temperature aerogel powder described in this embodiment is prepared by the following method, and the steps are as follows:

[0062] Weigh a certain amount of tetraethyl orthosilicate, gradually add 1.0 mol / L dilute hydrochloric acid solution, control the pH at about 3.5, stir for 30 minutes, stop adding acid after gelation occurs, then add 1 mol / L ammonia solution to adjust the pH value of the system to alkaline 7.0, then heat to 60°C and age for 100 minutes; add an equal volume of a mixture consisting of tetraethyl orthosilicate, anhydrous ethanol and deionized water to the SiO2 wet gel, wherein the molar ratio of tetraethyl orthosilicate, anhydrous ethanol and deionized water in the mixture is 1:4:6; place the resulting reaction solution at 60°C for solvent replacement for 24 hours, and wash the aged gel with anhydrous ethanol until it is neutral; add hexamethyldisilazane at 60°C The surface of the SiO2 aerogel is modified by using a hexamethyldisilazane-ethanol mixed solution, wherein the hexamethyldisilazane-ethanol mixed solution is composed of hexamethyldisilazane and anhydrous ethanol, and the molar ratio of the hexamethyldisilazane to the anhydrous ethanol is 1.5:1. The surface modification reaction takes 24 hours. After the reaction, the obtained alcohol gel is placed in a supercritical ethanol kettle, anhydrous ethanol is added, and the kettle is sealed and dried after being purged with nitrogen. The temperature is raised to 260°C, and the pressure is maintained at 14MPa for 5 hours. After returning to normal pressure and purging with nitrogen for 10 minutes, the kettle can be opened to take out the hydrophobic SiO2 aerogel after cooling to room temperature. The SiO2 aerogel is placed in a reactor as a core material, and an aluminum source trimethylaluminum is introduced into the reactor in gaseous form to react with Si A chemical reaction occurs on the surface of the O2 aerogel to form a layer of aluminum compounds. The reactor is then purged with nitrogen to remove unreacted aluminum sources and by-products. Subsequently, oxygen source water vapor is introduced to react with the previously formed titanium compound to generate an Al2O3 shell. The reactor is also purged with nitrogen to remove unreacted oxygen sources and by-products. The above pulse and purge steps are repeated 50 times until the required number of Al2O3 particle layers is reached and the film thickness is about 5.0 nm to prepare a SiO2-based composite high-temperature aerogel with an appropriate amount of Al2O3 particle deposition; finally, the aerogel is fully mechanically ground into micro-nano particles to obtain SiO2@Al2O3 aerogel powder, which is subsequently used for coating preparation.

[0063] The present embodiment also provides a SiO2@Al2O3 aerogel slurry, in which the mass fraction of aerogel is 40wt%; the slurry is composed of a dispersant, a wetting agent, deionized water and SiO2@Al2O3 aerogel powder, wherein: the SiO2@Al2O3 aerogel powder is the SiO2@Al2O3 aerogel powder prepared by the method described above in the present embodiment; the dispersant is a sulfate ester salt; the wetting agent is polyvinyl alcohol; the mass ratio of the total mass of the dispersant and the wetting agent to the mass of the SiO2@Al2O3 aerogel powder is 0.18.

[0064] The preparation method of the SiO2@Al2O3 aerogel slurry is as follows: add the dispersant and the wetting agent into deionized water according to the ratio, stir evenly, then add the SiO2@Al2O3 aerogel powder, and disperse at high speed for 1 hour.

[0065] This embodiment also provides a high temperature resistant aerogel insulation coating composed of the following components:

[0066] 20 parts by mass of deionized water, 20 parts by mass of SiO2@Al2O3 aerogel slurry, 14.4 parts by mass of ceramic microspheres, 40 parts by mass of film-forming emulsion, 0.8 parts by mass of fiber, 0.6 parts by mass of flame retardant, 4 parts by mass of auxiliary agent, and 0.2 parts by mass of defoamer; wherein the SiO2@Al2O3 aerogel slurry powder is the SiO2@Al2O3 aerogel slurry prepared by the method described above; the ceramic microspheres are silicon-aluminum-based ceramic hollow microspheres with a compressive strength of 4000-6000 kg / cm 2 , thermal conductivity is 0.07~0.12W / (mk), and heat resistance temperature can reach 1000℃; film-forming emulsion is a mixture of elastic acrylic emulsion and silicone resin emulsion, with solid content of 50~60%, and weight ratio of elastic acrylic emulsion and silicone resin emulsion is 0.48; fiber is aluminum silicate fiber; flame retardant is ammonium polyphosphate; auxiliary agent is ethylene glycol butyl ether; defoamer is polyacrylate defoamer.

[0067] The preparation method of the high temperature resistant aerogel thermal insulation coating described above in this embodiment is as follows: deionized water, additives, defoaming agents, flame retardants, and film-forming emulsion are added to a dispersion kettle according to a ratio, stirred evenly, and dispersed at 200r / min for 15min; SiO2@Al2O3 aerogel slurry, ceramic microbeads and fibers are added to the mixed liquid in sequence, and dispersed at 800r / min for 1h until the mixture is evenly dispersed into a slurry-like coating to obtain the high temperature resistant aerogel thermal insulation coating.

[0068] Example 3

[0069] This embodiment first provides a SiO2-based composite high-temperature aerogel powder, specifically SiO2@ZrO2 aerogel powder; the particle size of the SiO2@ZrO2 aerogel powder is 50-80 μm, the hydrophobic angle reaches 120-140°, and the average thermal conductivity at 500°C is 0.076 W / (mk).

[0070] The SiO2-based composite high-temperature aerogel powder described in this embodiment is prepared by the following method, and the steps are as follows:

[0071] Weigh a certain amount of tetraethyl orthosilicate, gradually add 1.0 mol / L dilute hydrochloric acid solution, control the pH at about 4.0, stir for 30 minutes, stop adding acid after gelation occurs, then add 1 mol / L ammonia solution to adjust the pH value of the system to alkaline 8.0, then heat to 65°C and age for 100 minutes; add an equal volume of a mixed solution composed of tetraethyl orthosilicate, anhydrous ethanol and deionized water to the SiO2 wet gel, the molar ratio of tetraethyl orthosilicate, anhydrous ethanol and deionized water in the mixed solution is The reaction mixture was placed at 65°C for solvent replacement for 48 hours, and the aged gel was washed with anhydrous ethanol until neutral; at 65°C, a hexamethyldisilazane-ethanol mixed solution was added for surface modification, wherein the hexamethyldisilazane-ethanol mixed solution consisted of hexamethyldisilazane and anhydrous ethanol, and the molar ratio of the hexamethyldisilazane to the anhydrous ethanol was 1:1, and the surface modification reaction was carried out for 48 hours; after the reaction, the obtained alcohol gel was placed in a supercritical ethanol kettle, and anhydrous ethanol was added. Alcohol, seal the drying kettle after purging with nitrogen, heat to 270℃, maintain at 15MPa pressure for 6h, return to normal pressure and purge with nitrogen for 10min, cool to room temperature and then open the kettle to take out the hydrophobic SiO2 aerogel; place the SiO2 aerogel as the core material in the reactor, introduce the zirconium source tetrakis(diamino)zirconium into the reactor in gaseous form, react chemically with the surface of the SiO2 aerogel to form a layer of zirconium compound, then purge the reactor with nitrogen to remove unreacted zirconium source and by-products, then introduce oxygen source water vapor to react with the previously formed titanium compound to generate a ZrO2 shell, purge the reactor with nitrogen to remove unreacted oxygen source and by-products, repeat the above pulse and purge steps 100 times until the required number of ZrO2 particle layers is reached, and the film thickness is about 5.0nm to prepare a SiO2-based composite high-temperature aerogel with a large number of ZrO2 particles deposited; the aerogel is fully mechanically ground into micro-nano particles to obtain aerogel powder, which is subsequently used for coating preparation.

[0072] The present embodiment also provides a SiO2@ZrO2 aerogel slurry, in which the mass fraction of aerogel is 40wt%; the slurry is composed of a dispersant, a wetting agent, deionized water and SiO2@ZrO2 aerogel powder, wherein: the SiO2@ZrO2 aerogel powder is the SiO2@ZrO2 aerogel powder prepared by the method described above in the present embodiment; the dispersant is selected from ammonium polyacrylate; the wetting agent is selected from polyether modified polydimethylsiloxane; the mass ratio of the total mass of the dispersant and the wetting agent to the SiO2@ZrO2 aerogel powder is 0.30.

[0073] The preparation method of the SiO2@ZrO2 aerogel slurry is as follows: add the dispersant and the wetting agent into deionized water according to the ratio, stir evenly, then add the SiO2@ZrO2 aerogel powder, and disperse at high speed for 1 hour.

[0074] This embodiment also provides a high temperature resistant aerogel thermal insulation coating composed of the following components:

[0075] 20 parts by mass of deionized water, 25 parts by mass of SiO2@ZrO2 aerogel slurry, 15 parts by mass of ceramic microspheres, 34.8 parts by mass of film-forming emulsion, 0.6 parts by mass of fiber, 0.4 parts by mass of flame retardant, 4 parts by mass of auxiliary agent, and 0.2 parts by mass of defoaming agent; wherein, the SiO2@ZrO2 aerogel slurry is the SiO2@ZrO2 aerogel slurry prepared by the method described above in this embodiment; the ceramic microspheres are selected from silicon-aluminum-based ceramic hollow microspheres with a compressive strength of 4000-6000 kg / cm 2 , thermal conductivity is 0.07~0.12W / (mk), and heat resistance temperature can reach 1000℃; film-forming emulsion is a mixture of elastic acrylic emulsion and silicone resin emulsion, with solid content of 50~60%, and weight ratio of elastic acrylic emulsion and silicone resin emulsion is 0.60; mullite fiber is selected as fiber; zinc borate is selected as flame retardant; alcohol ester-12 is selected as additive; polyether defoamer is selected as defoamer.

[0076] Comparative Example 1

[0077] A high temperature resistant aerogel insulation coating of the present comparative example is composed of the following components: 20 parts by mass of deionized water, 25 parts by mass of aerogel slurry, 15 parts by mass of ceramic microspheres, 34.8 parts by mass of film-forming emulsion, 0.6 parts by mass of fiber, 0.4 parts by mass of flame retardant, 4 parts by mass of auxiliary agent, and 0.2 parts by mass of defoamer; wherein, the particle size of SiO2 aerogel powder is 50-80 μm, the average thermal conductivity at 500 ° C is 0.080-0.100 W / (mk), and the hydrophobic angle is 120-140°; the dispersant is polyacrylic acid ammonium salt; the wetting agent is polyether modified polydimethylsiloxane; the ceramic microspheres are silicon aluminum-based ceramic hollow microspheres, and the compressive strength is 4000-6000 kg / cm 2 , thermal conductivity is 0.07~0.12W / (mk), and heat resistance temperature can reach 1000℃; film-forming emulsion is a mixture of elastic acrylic emulsion and silicone resin emulsion, with solid content of 50~60%, and weight ratio of elastic acrylic emulsion and silicone resin emulsion is 0.60; mullite fiber is selected as fiber; zinc borate is selected as flame retardant; alcohol ester-12 is selected as additive; polyether defoamer is selected as defoamer.

[0078] Among them, the preparation process of SiO2 aerogel is:

[0079] Weigh a certain amount of tetraethyl orthosilicate, gradually add 1.0 mol / L dilute hydrochloric acid solution, control the pH at about 3.0, stir for 30 minutes, stop adding acid after gelation occurs, then add 1 mol / L ammonia solution to adjust the pH value of the system to alkaline 6.5, then heat to 55°C and age for 100 minutes; add an equal volume of a mixed solution composed of tetraethyl orthosilicate, anhydrous ethanol and deionized water to the SiO2 wet gel, the molar ratio of tetraethyl orthosilicate, anhydrous ethanol and deionized water in the mixed solution is 1:4:6; place the resulting reaction solution at 55°C for solvent replacement for 12 hours, and age the gel with anhydrous ethanol The mixture was washed with alcohol until neutral; at 55°C, a hexamethyldisilazane-ethanol mixed solution was added for surface modification, wherein the hexamethyldisilazane-ethanol mixed solution consisted of hexamethyldisilazane and anhydrous ethanol, and the molar ratio of the hexamethyldisilazane and anhydrous ethanol was 2:1, and the surface modification reaction was carried out for 12 hours; after the reaction, the obtained alcohol gel was placed in a supercritical ethanol kettle, anhydrous ethanol was added, and the kettle was sealed and dried after being purged with nitrogen, and the temperature was raised to 250°C, and maintained at a pressure of 13MPa for 4 hours, and after returning to normal pressure, nitrogen was purged for 10 minutes, and the hydrophobic SiO2 aerogel was taken out after being cooled to room temperature.

[0080] The steps for preparing the aerogel slurry and the coating are as shown in Example 1, wherein the mass ratio of the wetting agent / dispersant to the aerogel used in the aerogel slurry preparation process is 0.30.

[0081] Table 1 Performance parameters of high temperature resistant aerogel insulation coatings prepared in different embodiments

[0082]

[0083] The high temperature resistant aerogel insulation coating prepared in the embodiment is tested in accordance with GB / T 10294-2008 "Determination of steady-state thermal resistance and related properties of insulation materials - Guarded hot plate method", GB / T1720-2020 "Paint film circle test" and GB / T17371-2008 "Silicate composite insulation coating" standards. The average extinction coefficient is calculated by using the average extinction coefficient (radiation characteristic) prediction model established by Mile scattering theory, Beer's law and radiation heat transfer equation. The relevant parameters are shown in Table 1.

[0084] The study found that the high-temperature thermal conductivity of the high-temperature thermal insulation coating prepared from SiO2-based composite aerogel prepared by atomic layer vapor deposition is relatively excellent. The introduction of TiO2, ZrO2, and Al2O3 particle infrared shading agents significantly improves the extinction coefficient and high-temperature thermal insulation performance. The surface adjustability of the aerogel is regulated by controlling the number of cycles. The lower the contact angle of the surface of the prepared SiO2-based composite aerogel, the better its compatibility with the aqueous emulsion matrix, so that the coating can be completely spread on the surface of the coating, thereby obtaining good adhesion and high-temperature resistant mechanical properties.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A SiO2-based composite high-temperature aerogel, characterized in that: Specifically, it is any one of SiO2@TiO2, SiO2@ZrO2 or SiO2@Al2O3.

2. The SiO2-based composite high-temperature aerogel according to claim 1, characterized in that: The SiO2-based composite high-temperature aerogel is preferably a SiO2-based composite high-temperature aerogel powder, the aerogel powder has a particle size of 50 to 80 μm, an average thermal conductivity of 0.065 to 0.085 W / (mk) at 500°C, and a hydrophobic angle of 110 to 130°.

3. The method for preparing the SiO2-based composite high-temperature aerogel according to claim 1, characterized in that: Here are the steps: Deionized water is added to the titanium source, zirconium source or aluminum source, and the mixture is mixed evenly. The obtained mixed solution is deposited on the surface of the SiO2 aerogel by atomic vapor deposition to obtain the SiO2-based composite high-temperature aerogel.

4. The preparation method according to claim 3, characterized in that: The SiO2 aerogel is prepared by the following method, the steps are as follows: (1) gradually adding a dilute hydrochloric acid solution to the silicon source solution, controlling the pH value between 3 and 4, stirring until gelation occurs and then stopping the acid addition, then adding an ammonia solution to adjust the pH value of the system to 6.5 to 8, then heating to 55 to 65° C. and aging for 100 minutes to obtain SiO2 wet gel; (2) adding a mixed solution of tetraethyl orthosilicate, anhydrous ethanol and deionized water to the SiO2 wet gel, placing the resulting reaction solution at 55 to 65° C. for solvent replacement for 12 to 48 hours, and washing the resulting product with anhydrous ethanol until it is neutral to obtain an aged gel; (3) adding a hexamethyldisilazane-ethanol mixed solution to the aged gel at 55-65° C. to carry out a surface modification reaction for 12-48 hours; after the reaction, subjecting the obtained alcohol gel to supercritical drying to obtain SiO2 aerogel.

5. The preparation method according to claim 4, characterized in that: The molar ratio of ethyl orthosilicate, anhydrous ethanol and deionized water in the mixed solution of step (2) is 1:4:

6.

6. A SiO2-based composite high-temperature aerogel slurry, comprising a dispersant, a wetting agent, deionized water and a SiO2-based composite high-temperature aerogel, characterized in that: The SiO2-based composite high-temperature aerogel is the SiO2-based composite high-temperature aerogel described in claim 1.

7. The SiO2-based composite high-temperature aerogel slurry according to claim 6, characterized in that: The mass ratio of the total mass of the wetting agent and the dispersant to the mass of the aerogel is 0.05-0.5:

1.

8. A high temperature resistant aerogel thermal insulation coating, comprising the following raw materials in parts by weight: 10-20 parts of deionized water Aerogel slurry 15-25 parts Features: The SiO2-based composite high-temperature aerogel is the SiO2-based composite high-temperature aerogel described in claim 1.

9. The high temperature resistant aerogel thermal insulation coating according to claim 8, characterized in that: The ceramic microspheres are hollow silicon-aluminum-based ceramic microspheres with a compressive strength of 4000-6000 kg / cm 2 The thermal conductivity is 0.07~0.12W / (mk) and the heat resistance temperature reaches 1000℃.

10. The high temperature resistant aerogel thermal insulation coating according to claim 8, characterized in that: The film-forming emulsion is a mixture of elastic acrylic emulsion and organic silicone resin emulsion, with a solid content of 50-60%, and a weight ratio of the elastic acrylic emulsion to the organic silicone resin emulsion of 0.35-0.60.

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