Cement-based aerogel material and preparation method thereof

Abstract

The invention discloses a cement-based aerogel material and a preparation method thereof, and belongs to the field of functional materials. The cement-based aerogel material comprises the following components in parts by mass: 1-5 parts of a water-based polymer modifier, 1-5 parts of a phase change material, 3-15 parts of a coating material, 1-3 parts of a basic catalyst, 5-10 parts of a foaming agent, 5-20 parts of cement, 1-3 parts of a flame retardant and 5-20 parts of water, the phase change material is paraffin, and the coating material is tetraethyl orthosilicate or tetrabutyl orthosilicate. The preparation method comprises the following steps: (1) mixing polyvinyl alcohol and water, and adding a phase change material and a coating material; (2) adding a basic catalyst, and reacting; (3) adding a foaming agent, cement and a flame retardant to prepare slurry; and (4) pouring the slurry into a mold, and placing the mold in a liquid nitrogen pool for freezing and pore-forming to obtain the cement-based aerogel material. The cement-based aerogel material provided by the invention can achieve the effects of low cost, high strength and excellent heat insulation performance.

Description

Technical Field

[0001] This invention relates to functional materials, and more particularly to a cement-based aerogel material and its preparation method. Background Technology

[0002] Thermal insulation materials are crucial for ensuring the safety of equipment and personnel under high-temperature conditions, playing a vital role in various fields. In the power battery industry, thermal insulation materials are the core of battery safety. By placing high-efficiency materials such as aerogel insulation sheets between battery cells, they effectively block the temperature difference between individual cells during thermal runaway, slow down the rate of heat spread, buy valuable escape time for occupants, and protect the structural integrity of the battery pack. In the chemical industry, thermal insulation technology is widely used in high-temperature reactors, pipelines, and storage tanks. It not only reduces heat loss and significantly improves energy efficiency but also creates a safe production environment by maintaining the low temperature of the equipment's outer walls, effectively preventing burns to workers and secondary accidents. In the construction industry, thermal insulation is directly related to the energy efficiency and comfort of buildings. By applying thermal insulation materials to walls and roofs, heat transfer between the outdoors and indoors can be significantly reduced, achieving the goal of saving air conditioning energy consumption in summer and maintaining indoor warmth in winter, thus contributing to the development of green and low-carbon buildings.

[0003] Existing thermal insulation materials mainly include inorganic fibers, organic polymers, and aerogels. Inorganic fiber thermal insulation materials primarily include rock wool and glass wool. These materials are fire-resistant and high-temperature resistant, widely used in buildings and industrial pipelines, but their thermal insulation effect is poor and cannot meet the high requirements for thermal insulation. Organic polymer thermal insulation materials primarily include polystyrene and polyurethane foam. These materials are lightweight and have excellent thermal insulation performance, often used in building insulation, but their flammability or combustibility poses significant safety hazards. Aerogel thermal insulation materials have a nanoporous structure and are used in fields with stringent space and performance requirements, such as power batteries. As an emerging material, it has extremely low thermal conductivity and good thermal insulation and flame retardant effects, and has become a popular material in the high-end thermal insulation field.

[0004] The conventional method for preparing aerogels is supercritical drying. CN108636304A provides a method for preparing aerogels using supercritical drying, which has high pore-forming ability and extremely low thermal conductivity (0.017~0.022 W / (m·K)). However, this preparation method involves complex equipment and processes, resulting in high costs, which greatly limits the industrial application of aerogel materials. CN119912225A provides a low-cost aerogel material and its preparation method, which uses liquid nitrogen freezing to create pores instead of supercritical drying and uses cement-based materials instead of ceramic-based materials, significantly reducing the cost of aerogel materials. The thermal conductivity can be as low as 0.037 W / (m·K), and the density is only 89 kg / m³. 3However, its compressive strength is only 0.72~0.93 MPa, which is difficult to meet the requirements of applications with high mechanical strength. CN116854426A provides a method for preparing foamed concrete based on aerogel modified with phase change material. Inorganic hydrated salt phase change material is loaded into the pore structure of ceramic-based aerogel, and then this modified aerogel material is used to prepare foamed concrete thermal insulation material. This material has a high compressive strength of 1.57~2.23 MPa and a fire resistance rating, but its thermal conductivity is high, reaching 0.10~0.14 W / (m・K). Although it has high mechanical strength performance, its thermal insulation effect cannot meet the requirements of power batteries and other fields.

[0005] Although conventional aerogel materials have the advantages of extremely low thermal conductivity, good heat insulation and flame retardancy, their high cost, low strength and brittleness are the core bottlenecks that limit their application. The contradiction between heat insulation effect and mechanical strength has always been difficult to solve. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a cement-based aerogel material that is low in cost, high in strength, and has excellent thermal insulation properties.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned cement-based aerogel material.

[0008] Technical solution: The cement-based aerogel material of the present invention comprises, by mass fraction, 1-5 parts of water-based polymer modifier, 1-5 parts of phase change material, 3-15 parts of coating material, 1-3 parts of alkaline catalyst, 5-10 parts of foaming agent, 5-20 parts of cement, 1-3 parts of flame retardant, and 5-20 parts of water. The phase change material is paraffin wax, the coating material is tetraethyl orthosilicate or tetrabutyl orthosilicate, and the water-based polymer modifier is polyvinyl alcohol.

[0009] Preferably, the cement is silicate cement with a strength grade of not less than 42.5.

[0010] Preferably, the flame retardant is aluminum hydroxide or magnesium hydroxide.

[0011] Preferably, the foaming agent is 25-35 wt% hydrogen peroxide.

[0012] Preferably, the viscosity-average molecular weight of the polyvinyl alcohol is 100,000 to 300,000.

[0013] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix polyvinyl alcohol and water, add paraffin and coating material, and stir to form a suspension; (2) Add an alkaline catalyst and stir the reaction. (3) Add foaming agent, cement and flame retardant in sequence to obtain slurry; (4) Pour the above slurry into a mold and place it in a liquid nitrogen pool for freezing and pore creation to obtain cement-based aerogel material.

[0014] The reaction time in step (2) is 2-6 hours.

[0015] The volume of the slurry in step (4) is about half or more of the volume of the mold; the freezing and hole-making time is 40 min to 2 h; after the freezing and hole-making is completed, the slurry is thawed and drained, and then placed in an environment of 40~45℃ for curing.

[0016] Invention Principle: The thermal insulation effect of aerogel materials is highly correlated with their porosity. Generally, higher porosity results in lower thermal conductivity, but also leads to a significant decrease in the material's mechanical strength. To overcome this drawback, this invention uses phase change materials (PCMs) to modify cement-based aerogel materials. The PCM acts as a heat storage unit at high temperatures, significantly improving the thermal insulation effect of the aerogel material. Furthermore, to enhance the recyclability of the PCM in the aerogel material, this invention uses silica to coat the PCM. This coating not only prevents leakage of the PCM during recycling but also synergizes with the cement-based material, significantly improving the mechanical properties of the aerogel material.

[0017] Therefore, the cement-based aerogel material and its preparation method provided by this invention achieve the synergistic effect of low cost, low thermal conductivity, and high strength of aerogel materials for thermal insulation and protection.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The present invention uses amorphous silica to coat the phase change material, which greatly improves the thermal insulation performance of the aerogel material, and the thermal conductivity is only 0.029~0.05 W / (m・K); (2) Using cement as the matrix, the cost is greatly reduced compared with the traditional nano silica, and the compressive strength is improved; (3) The cement-based aerogel material prepared by this method has low thermal conductivity and excellent thermal insulation effect, while also having high mechanical strength, which solves the contradiction between thermal insulation effect and mechanical strength; (4) The traditional supercritical drying method uses carbon dioxide as a pore-forming agent and requires high-temperature calcination, while the present invention uses a freeze pore-forming process to prepare cement-based aerogel material, using water as a pore-forming agent, which does not require high-temperature calcination, but only low-temperature curing, saving costs and resources. Attached Figure Description

[0019] Figure 1 The image shows a CT image of the cement-based aerogel material prepared in Example 1. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the embodiments.

[0021] Example 1

[0022] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 44g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 3180g of water, stir to dissolve, add 60g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve and 160g of tetraethyl orthosilicate, and stir to form a suspension.

[0023] (2) Add 48g of 32wt% liquid alkali to the above suspension and stir for 2.5 hours.

[0024] (3) Add 240g of 30wt% hydrogen peroxide, 220g of P.O52.5 cement and 48g of aluminum hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0025] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0026] Example 2

[0027] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 100g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 2460g of water, stir to dissolve, add 120g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve and 360g of tetraethyl orthosilicate, and stir to form a suspension.

[0028] (2) Add 80g of 32wt% liquid alkali to the above suspension and stir for 2.5 hours.

[0029] (3) Add 320g of 30wt% hydrogen peroxide, 480g of P.O52.5 cement and 80g of aluminum hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0030] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0031] Example 3

[0032] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 180g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 1680g of water, stir to dissolve, add 190g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve and 580g of tetraethyl orthosilicate, and stir to form a suspension.

[0033] (2) Add 115g of 32wt% liquid alkali to the above suspension and stir for 2.5 hours.

[0034] (3) Add 380g of 30wt% hydrogen peroxide, 760g of P.O52.5 cement and 115g of aluminum hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0035] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0036] Example 4

[0037] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 44g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 2890g of water, stir to dissolve, add 120g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve and 360g of tetraethyl orthosilicate, and stir to form a suspension.

[0038] (2) Add 80g of 32wt% liquid alkali to the above suspension and stir for 2.5 hours.

[0039] (3) Add 240g of 30wt% hydrogen peroxide, 220g of P.O52.5 cement and 48g of aluminum hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0040] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0041] Example 5

[0042] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 44g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 2560g of water, stir to dissolve, add 190g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve and 580g of tetraethyl orthosilicate, and stir to form a suspension.

[0043] (2) Add 115g of 32wt% liquid alkali to the above suspension and stir for 2.5 hours.

[0044] (3) Add 240g of 30wt% hydrogen peroxide, 220g of P.O52.5 cement and 48g of aluminum hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0045] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0046] Example 6

[0047] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 180g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 1960g of water, stir to dissolve, add 190g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve and 580g of tetraethyl orthosilicate, and stir to form a suspension.

[0048] (2) Add 115g of 32wt% liquid alkali to the above suspension and stir for 2.5 hours.

[0049] (3) Add 380g of 30wt% hydrogen peroxide, 480g of P.O52.5 cement and 115g of aluminum hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0050] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0051] Example 7

[0052] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 180g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 2220g of water, stir to dissolve, add 190g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve and 580g of tetraethyl orthosilicate, and stir to form a suspension.

[0053] (2) Add 115g of 32wt% liquid alkali to the above suspension and stir for 2.5 hours.

[0054] (3) Add 380g of 30wt% hydrogen peroxide, 220g of P.O52.5 cement and 115g of aluminum hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0055] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0056] Example 8

[0057] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 44g of polyvinyl alcohol with a viscosity-average molecular weight of 300,000 and 3180g of water, stir to dissolve, add 60g of paraffin powder with a melting point of 65℃ and passing through a 200-mesh sieve and 160g of tetrabutyl orthosilicate, and stir to form a suspension.

[0058] (2) Add 48g of 32wt% liquid alkali to the above suspension and stir for 4 hours.

[0059] (3) Add 240g of 30wt% hydrogen peroxide, 220g of P.O62.5 cement and 48g of magnesium hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0060] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 40 minutes, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for curing for 14 days, demold, and obtain a plate-shaped cement-based aerogel material.

[0061] Example 9

[0062] The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 44g of polyvinyl alcohol with a viscosity-average molecular weight of 120,000 and 3180g of water, stir to dissolve, add 60g of paraffin powder with a melting point of 65℃ and passing through a 200-mesh sieve and 160g of tetrabutyl orthosilicate, and stir to form a suspension.

[0063] (2) Add 48g of 32wt% liquid alkali to the above suspension and stir for 5.5 hours.

[0064] (3) Add 240g of 30wt% hydrogen peroxide, 220g of P.O42.5 cement and 48g of magnesium hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0065] (4) Pour the above slurry into the mold. The volume of the slurry is about half the volume of the mold. Then place the mold in a liquid nitrogen pool for freezing and hole making. After 1 hour, take it out of the mold and place it in an environment of 2~8℃ to thaw and drain for 3 days. Then place it in an environment of 40~45℃ for curing for 14 days. Demold the mold to obtain a plate-shaped cement-based aerogel material.

[0066] Comparative Example 1 The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 44g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 3440g of water and stir to dissolve.

[0067] (2) Add 240g of 30wt% hydrogen peroxide, 220g of P.O52.5 cement and 48g of aluminum hydroxide fine powder passing through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0068] (3) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0069] Comparative Example 2 The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 44g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 3380g of water, stir to dissolve, add 60g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve, and stir to form a suspension.

[0070] (2) Add 240g of 30wt% hydrogen peroxide, 220g of P.O52.5 cement and 48g of aluminum hydroxide fine powder passing through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0071] (3) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0072] Comparative Example 3 The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 3220g of water, 60g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve and 160g of tetraethyl orthosilicate and stir to form a suspension.

[0073] (2) Add 48g of 32wt% liquid alkali to the above suspension and stir for 2.5 hours.

[0074] (3) Add 240g of 30wt% hydrogen peroxide, 220g of P.O52.5 cement and 48g of aluminum hydroxide fine powder that has passed through a 200-mesh sieve in sequence, and stir evenly to obtain a slurry.

[0075] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0076] Comparative Example 4 The method for preparing the cement-based aerogel material of the present invention includes the following steps: (1) Mix 44g of polyvinyl alcohol with a viscosity-average molecular weight of 200,000 and 3420g of water, stir to dissolve, add 60g of paraffin powder with a melting point of 52℃ and passing through a 200-mesh sieve and 160g of tetraethyl orthosilicate, and stir to form a suspension.

[0077] (2) Add 48g of 32wt% liquid alkali to the above suspension and stir for 2.5 hours.

[0078] (3) 220g of P.O52.5 cement and 48g of aluminum hydroxide fine powder passing through a 200-mesh sieve were mixed evenly to obtain a slurry.

[0079] (4) Pour the above slurry into the mold, the volume of the slurry is about half the volume of the mold, and then place the mold in a liquid nitrogen pool for freezing and hole making; after 2 hours, take it out of the mold, place it in an environment of 2~8℃ to thaw and drain for 3 days, and then place it in an environment of 40~45℃ for 14 days to cure, demold, and obtain a plate-shaped cement-based aerogel material.

[0080] Comparative Example 5 Traditional commercially available rock wool boards.

[0081] Comparative Example 6 Traditional commercially available polystyrene boards.

[0082] Comparative Example 7 Traditional commercially available silica aerogel insulation panels.

[0083] The raw material formulations for each embodiment and comparative example are shown in Table 1.

[0084] Table 1. Raw material ratios (wt%) for each embodiment and comparative example

[0085] sample Polyvinyl alcohol paraffin silicon salts catalyst hydrogen peroxide cement Flame retardant water Example 1 1.1 1.5 4.0 1.2 6.0 5.5 1.2 79.5 Example 2 2.5 3.0 9.0 2.0 8.0 12.0 2.0 61.5 Example 3 4.5 4.8 14.5 2.9 9.5 19.0 2.9 42.0 Example 4 1.1 3.0 9.0 2.0 6.0 5.5 1.2 72.2 Example 5 1.1 4.8 14.5 2.9 6.0 5.5 1.2 64.0 Example 6 4.5 4.8 14.5 2.9 9.5 12.0 2.9 49.0 Example 7 4.5 4.8 14.5 2.9 9.5 5.5 2.9 55.5 Example 8 1.1 1.5 4.0 1.2 6.0 5.5 1.2 79.5 Example 9 1.1 1.5 4.0 1.2 6.0 5.5 1.2 79.5 Comparative Example 1 1.1 0.0 0.0 0.0 6.0 5.5 1.2 86.2 Comparative Example 2 1.1 1.5 0.0 0.0 6.0 5.5 1.2 84.7 Comparative Example 3 0.0 1.5 4.0 1.2 6.0 5.5 1.2 80.6 Comparative Example 4 1.1 1.5 4.0 1.2 0.0 5.5 1.2 85.5

[0086] According to the test methods and conditions in the national standard GB / T 34336-2017 "Nanoporous Aerogel Composite Thermal Insulation Products", the aerogel materials obtained in each experiment were tested, including thermal conductivity, flammability rating, and compressive strength. Different samples were cut into 100cm × 10cm × 2cm dimensions and subjected to a 60-minute thermal insulation test in an air atmosphere at 150℃ using a single-sided heating furnace. That is, one side of the sample was heated to 150℃, and after 60 minutes, the temperature of the other side was measured; this is referred to as the cold side temperature. The test results are shown in Table 2. Notably, the board obtained in Comparative Example 3 cracked, and no related tests were performed.

[0087] Table 2 Performance test results of each sample

[0088] sample Thermal conductivity (W / (m・K)) Compressive strength (MPa) Combustion rating Cold side temperature (°C) Example 1 0.037 2.35 A 38.2 Example 2 0.041 3.62 A 36.3 Example 3 0.050 5.18 A 34.7 Example 4 0.033 2.69 A 33.1 Example 5 0.029 3.07 A 31.2 Example 6 0.046 4.51 A 34.1 Example 7 0.040 3.63 A 33.8 Example 8 0.038 3.52 A 38.3 Example 9 0.039 2.14 A 37.6 Comparative Example 1 0.039 1.82 A 52.6 Comparative Example 2 0.037 1.86 B2 48.2 Comparative Example 4 0.119 4.32 A 65.7 Comparative Example 5 0.041 / A 49.6 Comparative Example 6 0.038 / B1 40.6 Comparative Example 7 0.027 <1 MPa A 31.5

[0089] Depend on Figure 1 It can be seen that the cement-based aerogel material prepared by this method has a porous structure. The black area of ​​the block in the figure is the pore, the white and light gray areas are the solid, and the stripes in the figure are the oriented pores. The material has high porosity and the pores are regularly oriented.

[0090] As shown in Table 2, the aerogel material prepared using the formulation and process of the present invention has both low thermal conductivity and high mechanical strength. The thermal conductivity does not exceed 0.05 W / (m・K), and the compressive strength is higher than 2 MPa. In the thermal insulation performance test, after the hot side of the material is kept at 150°C for 60 minutes, the temperature of the cold side is lower than 40°C. Analyzing Table 2, with the increase of the amount of phase change material and coating material (Examples 1, 4, 5), the thermal conductivity of the aerogel material decreased while the compressive strength increased. This indicates that paraffin, as a phase change material, has a good thermal insulation effect. The coating material, nano-silica, can participate in the hydration process of cement, thereby improving the compressive strength of the aerogel material. If no phase change material and coating material are added (Comparative Example 1), the aerogel material has a low thermal conductivity at room temperature (25℃), but poor long-term thermal insulation performance at high temperature (150℃). After the hot side of the material is kept at 150℃ for 60 minutes, the cold side temperature reaches 52.6℃. If no coating material is added (Comparative Example 2), the target material not only has poor thermal insulation performance, but its combustion rating can only reach B2, which does not meet the requirements. This is because the surface of the phase change material is not coated with amorphous silica, which is easy to leak after melting when heated, thus losing its thermal insulation effect.

[0091] When the water content decreases and the solids content increases (Examples 1-3), the porosity of the material decreases, the compressive strength increases significantly, and the thermal conductivity also increases.

[0092] As the amount of cement used in the aerogel material decreases (Examples 3, 6, 7), the porosity increases, the thermal conductivity of the aerogel material decreases, and the compressive strength also decreases significantly. At the same time, the aerogel material exhibits good flame retardant and fire resistant rating (Class A) and heat insulation effect (cold side temperature is below 40°C).

[0093] In Comparative Example 3, the lack of a water-based polymer modifier resulted in high brittleness of the aerogel material, leading to breakage of the aerogel sheet during curing and demolding, making subsequent performance testing impossible. In Comparative Example 4, no foaming agent was added. However, the foaming agent in the preparation process of the aerogel material of this invention provides rapid expansion, which significantly increases the porosity of the material. Therefore, without the addition of a foaming agent, the porosity of the material decreases, the thermal conductivity increases significantly, and the insulation performance is the worst (hot side temperature 150°C, cold side temperature 65.7°C after 60 minutes).

[0094] In addition, relevant tests were also conducted on three traditional commercially available thermal insulation materials (comparative examples 5-7). The test results show that although rock wool boards, polystyrene boards, and aerogel insulation boards all have low thermal conductivity, their compressive strength is extremely low, making them unsuitable for applications requiring high mechanical strength.

Claims

1. A cement-based aerogel material, characterized in that, By mass fraction, it includes 1-5 parts of water-based polymer modifier, 1-5 parts of phase change material, 3-15 parts of coating material, 1-3 parts of alkaline catalyst, 5-10 parts of foaming agent, 5-20 parts of cement, 1-3 parts of flame retardant, and 5-20 parts of water. The phase change material is paraffin wax, the coating material is tetraethyl orthosilicate or tetrabutyl orthosilicate, and the water-based polymer modifier is polyvinyl alcohol.

2. The cement-based aerogel material according to claim 1, characterized in that, The cement is silicate cement with a strength grade of not less than 42.

5.

3. The cement-based aerogel material according to claim 1, characterized in that, The flame retardant is aluminum hydroxide or magnesium hydroxide.

4. The cement-based aerogel material according to claim 1, characterized in that, The foaming agent is 25-35 wt% hydrogen peroxide.

5. The cement-based aerogel material according to claim 1, characterized in that, The viscosity-average molecular weight of the polyvinyl alcohol is 100,000 to 300,000.

6. A method for preparing the cement-based aerogel material according to claim 1, characterized in that, Includes the following steps: (1) Mix polyvinyl alcohol and water, add paraffin and coating material, and stir to form a suspension; (2) Add an alkaline catalyst and stir the reaction. (3) Add foaming agent, cement and flame retardant in sequence to obtain slurry; (4) Pour the above slurry into a mold and place it in a liquid nitrogen pool for freezing and pore creation to obtain cement-based aerogel material.

7. The preparation method according to claim 6, characterized in that, The reaction time described in step (2) is 2-6 hours.

8. The preparation method according to claim 6, characterized in that, The volume of the slurry in step (4) is half or more of the volume of the mold.

9. The preparation method according to claim 6, characterized in that, The cryopreservation time in step (4) is 40 minutes to 2 hours.

10. The preparation method according to claim 6, characterized in that, After the cryopreservation process described in step (4) is completed, the frozen material is thawed and drained, and then placed in an environment of 40~45℃ for curing.

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