A multifunctional integrated fiber-doped aerogel

Abstract

The present invention discloses a multifunctional integrated fiber-doped aerogel, which belongs to the technical field of material structure design. The fiber-doped aerogel of the present invention includes a nanoporous aerogel, a fiber-reinforced component that is directionally arranged and overlapped in the nanoporous aerogel, and a bonding layer; the raw material of the fiber-reinforced component is a micron core-shell fiber; the bonding layer is attached to the outside of the aerogel nanoparticles constituting the nanoporous aerogel to form a covering layer. The present invention aims to break through the limitations of traditional materials in the prior art and design a new type of multifunctional integrated fiber-doped aerogel. This new material not only has excellent thermal insulation performance, but also has strong mechanical bearing capacity, and at the same time exhibits an extremely low thermal expansion coefficient, so that it can maintain excellent stability and durability in various extreme environments. This material can still maintain a low internal temperature in a high temperature environment, and maintain a stable volume and shape, and can provide excellent thermal insulation protection.

Description

Technical Field

[0001] The invention relates to the technical field of material structure design, and in particular to a multifunctional integrated fiber-doped aerogel. Background Art

[0002] In order to mitigate the interference of temperature fluctuations on the detection of gravitational wave signals, the spacecraft thermal insulation protection system must have extremely high temperature stability to effectively block the heat flow from the spacecraft's external environment and ensure the safety of the spacecraft in service. Therefore, it is urgent to develop an integrated thermal insulation material with high efficiency, high load-bearing capacity and low thermal expansion to meet the comprehensive thermal protection needs of spacecraft.

[0003] Nanoporous aerogel materials have attracted extensive attention in the field of aerospace thermal protection due to their light weight and good thermal insulation performance. However, there are still some problems in the practical application of nanoporous aerogel materials: (1) The connection between nanoparticles in the skeleton structure of traditional nanoporous aerogel materials is prone to stress concentration, brittle fracture, and low overall mechanical strength. (2) Traditional nanoporous aerogel materials have poor thermal stability. Their nanoporous structures are greatly affected by temperature fluctuations, prone to volume shrinkage and structural deformation, and performance degradation during long-term service, affecting the safety and reliability of spacecraft operating in extreme environments. (3) Traditional nanoporous aerogel materials enhance their mechanical properties by doping with high-density fibers. However, doped fibers cannot meet the requirements of light weight, high-efficiency thermal insulation and high load-bearing capacity, which seriously limits the lightweight design of thermal protection systems. (4) The fiber skeleton of traditional fiber-doped aerogel composites is usually random, and it is difficult to control the fiber arrangement direction in a directional manner, resulting in the inability to effectively improve the thermal insulation, mechanical and thermal stability of the material in a specific direction, and cannot meet the application requirements of spacecraft thermal protection systems in complex thermal environments. Summary of the invention

[0004] The object of the present invention is to provide a multifunctional integrated fiber-doped aerogel. In the fiber-doped aerogel of the present invention, the adhesive layer covering the outer side of the aerogel nanoparticles constituting the nanoporous aerogel increases the neck bridging diameter between the particles, improves the weakness of the point contact between the particles, effectively prevents stress concentration at the neck connection, and enhances the mechanical bearing capacity of the nanoporous aerogel.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a multifunctional integrated fiber-doped aerogel, comprising a nanoporous aerogel, a fiber-reinforced component that is directionally arranged and overlapped with each other in the nanoporous aerogel, and a bonding layer; the raw material of the fiber-reinforced component is micron core-shell fiber; the bonding layer is attached to the outside of the aerogel nanoparticles constituting the nanoporous aerogel to form a covering layer.

[0007] Preferably, the fiber reinforcement components are arranged at an orientation angle of 10°-30°.

[0008] Preferably, the micron core-shell fiber comprises an outer negative thermal expansion layer and an inner inorganic fiber.

[0009] Preferably, the negative thermal expansion layer is zirconium tungsten ore and / or scandium gallium oxide; the inorganic fiber is one or more of mullite fiber, quartz fiber, basalt fiber and aluminum silicate fiber.

[0010] Preferably, the micron core-shell fiber has an aspect ratio of >2000 and a diameter of 2-20 μm, and the inner and outer diameter ratio of the outer negative thermal expansion layer and the inner inorganic fiber is 0-1 and is neither 0 nor 1.

[0011] Preferably, the bonding layer raw material includes one or more of epoxy resin, resorcinol-formaldehyde resin and phenolic resin, and the nanoporous aerogel is one or more of silicon dioxide aerogel, zirconium dioxide aerogel and aluminum oxide aerogel.

[0012] Preferably, the volume content of the adhesive layer in the multifunctional integrated fiber-doped aerogel is 5-10%, and the volume content of the nanoporous aerogel in the multifunctional integrated fiber-doped aerogel is 75-90%.

[0013] Preferably, the volume content of the fiber-reinforced component in the multifunctional integrated fiber-doped aerogel is 5-20%.

[0014] The thermal conductivity of the fiber-doped aerogel is less than 0.04 W·m -1 ·K -1 , elastic modulus>15MPa, thermal expansion coefficient is 1×10 -6 -1×10 -5 K -1 .

[0015] The second technical solution of the present invention is a method for preparing the multifunctional integrated fiber-doped aerogel, comprising the following steps:

[0016] Directly arranging the fiber-reinforced component, then adding a nanoporous aerogel raw material, performing gelation treatment and aging treatment to form an aerogel composite material containing the fiber-reinforced component;

[0017] The aerogel composite material containing the fiber-reinforced component is impregnated with the bonding layer solution and cured to obtain the multifunctional integrated fiber-doped aerogel.

[0018] Preferably, the fiber-reinforced component can be prepared by one or more of the following methods, including but not limited to: electrospinning technology, atomic layer deposition technology, chemical vapor deposition technology, electrophoretic deposition technology, sol-gel method or in-situ polymerization and high-temperature carbonization, etc. Preferably, the gelation treatment is maintained at 60-70°C for 4-6 hours, and the aging treatment is maintained at 80-100°C for 24 hours.

[0019] Preferably, the impregnation is vacuum impregnation.

[0020] Preferably, the curing treatment time is 2 hours.

[0021] A third technical solution of the present invention is the application of the above-mentioned multifunctional integrated fiber-doped aerogel in thermal insulation materials for aerospace vehicles.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] The multifunctional integrated fiber-doped aerogel of the present invention realizes the integration of multiple functions such as efficient thermal insulation, high load-bearing capacity, and low thermal expansion. The nanoporous aerogel is based on its unique three-dimensional continuous nanoporous network structure, showing extremely low density and thermal conductivity. The structure effectively inhibits the transmission of gas molecules and the formation of thermal bridges, significantly reduces the transfer and transport of heat, and can effectively block the influence of external environmental heat flow on spacecraft; the fiber-reinforced component significantly improves the mechanical strength and thermal stability of the aerogel structure, maintains the shape stability of the aerogel, effectively bears the load-bearing force of the nanoporous aerogel structure, prevents the brittle fracture of the aerogel skeleton structure, and reduces the influence of external environmental heat flow on the deformation of the nanoporous aerogel structure.

[0024] In the multifunctional integrated fiber-doped aerogel of the present invention, the adhesive layer covering the outside of the aerogel nanoparticles constituting the nanoporous aerogel increases the neck bridging diameter between the particles, improves the weakness of the point contact between the aerogel nanoparticles, effectively prevents stress concentration at the neck connection, and enhances the mechanical bearing capacity of the nanoporous aerogel.

[0025] In the multifunctional integrated fiber-doped aerogel of the present invention, the fiber-reinforced component is composed of directional arrangement of micron core-shell fibers containing internal inorganic fibers and external negative thermal expansion layers, which are overlapped with each other. This structure is not only controllable, but also the negative thermal expansion layer in the micron core-shell fiber significantly reduces the thermal expansion coefficient of the micron fiber, thereby improving the overall thermal stability of the material. According to the thermal protection application requirements of spacecraft in different service environments, the directional arrangement angle and doping volume fraction of the micron fiber can be adjusted to enhance the thermal insulation performance, mechanical strength and thermal stability in a specific direction, thereby significantly improving the comprehensive thermal protection effect of the fiber-doped aerogel and meeting the application requirements of the thermal protection system of the spacecraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Schematic diagram of the structural composition of multifunctional integrated fiber-doped aerogel.

[0028] In the figure, 1-multifunctional integrated fiber-doped aerogel, 2-aerogel nanoparticles, 3-adhesive layer, 4-inorganic fiber, 5-negative thermal expansion layer.

[0029] Figure 2 This is the influence of the directional arrangement angle and doping volume fraction of the fiber-reinforced component on the thermal conductivity of the product.

[0030] Figure 3 This is the influence of the directional arrangement angle and doping volume fraction of the fiber-reinforced component on the elastic modulus of the product.

[0031] Figure 4 This is the influence of the directional arrangement angle and doping volume fraction of the fiber-reinforced component on the thermal expansion coefficient of the product.

[0032] Figure 5 The effect of the neck bridge diameter between micron fibers on the stress distribution of the product. DETAILED DESCRIPTION

[0033] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0034] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0035] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in the present invention are open-ended terms, meaning including but not limited to.

[0037] All raw materials used in the following examples and comparative examples of the present invention are commercially available products.

[0038] The zirconium tungsten ore used in the following examples of the present invention is a composite oxide with a chemical formula of ZrW 2 O 8 . It has negative thermal expansion properties, which means that it contracts when heated instead of expanding like most materials. The specific source components of zirconium tungsten ore include zirconium, tungsten and oxygen, and are prepared by high-temperature solid-phase reaction. Its negative thermal expansion properties make it uniquely valuable for application in high-temperature thermal insulation materials, especially in the development of spacecraft thermal insulation materials. These properties ensure the excellent performance of fiber-doped aerogel in extreme thermal environments.

[0039] Example 1

[0040] Preparation of multifunctional integrated fiber-doped aerogel:

[0041] 100 mL of tetraethyl orthosilicate was used as a silicon source and 200 mL of ethanol was used as a solvent. The above raw materials were mixed with 50 mL of water, and 10 mL of hydrochloric acid (concentration 25%) was added as an acid catalyst. The mixture was stirred for 2 h at room temperature to preliminarily complete the hydrolysis reaction of tetraethyl orthosilicate. 10 mL of ammonia water (concentration 25%) was added as an alkaline catalyst, and the mixture was stirred for 6 h at 70 ° C to promote the condensation and crosslinking of the Si-O-Si network to obtain SiO 2 Sol.

[0042] Micron core-shell fibers were prepared by electrospinning combined with atomic layer deposition technology (the inner inorganic fiber material is mullite, the outer negative thermal expansion layer material is zirconium tungsten ore, the aspect ratio is 3000, the fiber diameter is 5μm, and the inner and outer diameter ratio is 0.7). First, mullite fibers were prepared by electrospinning technology, and then the zirconium tungsten ore layer was uniformly deposited on the fiber surface by atomic layer deposition technology to obtain micron core-shell fibers. Finally, the micron core-shell fibers were oriented and arranged by mechanical stretching technology to form a fiber-reinforced component. The micron core-shell fibers prepared by this method ensure that the zirconium tungsten ore is evenly covered on the outer layer of the inner inorganic fiber, thereby forming a fiber-reinforced component with excellent thermal and mechanical properties.

[0043] SiO was deposited by vacuum impregnation 2 The sol penetrates into the fiber reinforcement component, stands at 70°C for 4 hours for gelation, and then heats at 100°C for 24 hours for aging to form a SiO2 with a three-dimensional network structure. 2The gel is used to fix the micron fibers embedded in it. Finally, the SiO 2 The solvent and water in the gel are removed to obtain an aerogel composite material containing a fiber-reinforced component.

[0044] The epoxy resin is then introduced into the pore structure of the nanoporous aerogel by a vacuum impregnation method, and the epoxy resin is cured at room temperature for 2 hours to ensure that the epoxy resin is evenly coated on the surface of the aerogel nanoparticles and forms a stable bonding layer, and finally a fiber-doped aerogel is obtained (the volume fraction of the bonding layer in the fiber-doped aerogel is 5%; the doping volume fraction of the fiber-reinforced component is 10%, the volume fraction of the nanoporous aerogel in the fiber-doped aerogel is 85%, and the orientation angle of the directional arrangement is 20°).

[0045] The intrinsic solid phase thermal conductivity of the fiber-reinforced component prepared by the present invention is 6 W·m -1 ·K -1 , elastic modulus is 227.6GPa, thermal expansion coefficient is 5.3×10 -6 K -1 .

[0046] The density of the fiber-doped aerogel prepared by the present invention is 0.5 g·cm -3 , thermal conductivity is 0.036W·m -1 ·K -1 , elastic modulus is 25MPa, thermal expansion coefficient is 2×10 -6 K -1 .

[0047] Figure 1 Schematic diagram of the structural composition of multifunctional integrated fiber-doped aerogel. Figure 1 In the figure, the nanoporous aerogel is composed of interconnected aerogel nanoparticles 2, which are interconnected to form a three-dimensional network structure, and the surface of the three-dimensional network structure composed of aerogel nanoparticles 2 is attached with a bonding layer 3 (the three-dimensional network structure is completely filled with the bonding layer or not completely filled, the figure shows a completely filled state, and the incompletely filled state is not shown in the figure). The fiber reinforcement component is composed of inorganic fibers 4 and a negative thermal expansion layer 5, and these fibers are neatly arranged in the same direction and overlap each other to form a directional fiber skeleton.

[0048] Comparative Example 1

[0049] The only difference from Example 1 is that in preparing SiO 2 After sol formation, gelation and aging were carried out directly to obtain SiO2 without fiber doping. 2 Aerogel.

[0050] It was found that the undoped SiO 2The density of aerogel is 0.15 g cm -3 , the vacuum thermal conductivity is 0.005W·m -1 ·K -1 , elastic modulus is 8MPa, thermal expansion coefficient is 2.5×10 -6 K -1 .

[0051] Effect verification

[0052] (1) By adjusting only the directional arrangement angle and doping volume fraction of the fiber-reinforced component in Example 1, the effects on the thermal conductivity, elastic modulus and thermal expansion coefficient of the product were tested. The results are as follows: Figure 2-4 shown.

[0053] Figure 2 This is the influence of the directional arrangement angle and doping volume fraction of the fiber-reinforced component on the thermal conductivity of the product.

[0054] Figure 3 This is the influence of the directional arrangement angle and doping volume fraction of the fiber-reinforced component on the elastic modulus of the product.

[0055] Figure 4 This is the influence of the directional arrangement angle and doping volume fraction of the fiber-reinforced component on the thermal expansion coefficient of the product.

[0056] Depend on Figure 2-4 It can be seen that the doping volume fraction and directional arrangement angle of the fiber-reinforced component affect the thermal conductivity, elastic modulus and thermal expansion coefficient to a certain extent. By adjusting the doping volume fraction and directional arrangement angle of the fiber-reinforced component, the thermal conductivity, elastic modulus and thermal expansion coefficient of the output can be adjusted to a certain extent. Based on the consideration of product performance, the present invention limits the doping volume fraction of the fiber-reinforced component to 5-20% (10% optimal), and the orientation angle of the directional arrangement is limited to 10°-30° (20° optimal).

[0057] (2) The neck bridging diameter between aerogel nanoparticles in the product was adjusted by adjusting the proportion of the bonding layer in the fiber-doped aerogel (the bonding layer volume fraction of 0%, 2.5%, and 5% corresponded to the necking ratios of 0.526, 0.653, and 0.783, respectively), and its effect on the stress distribution of the product was tested. The results are shown in Figure 2. Figure 5 shown.

[0058] The calculation formula of the necking ratio is: Necking ratio (%) = (neck bridge diameter / aerogel nanoparticle diameter) × 100%

[0059] Figure 5 The effect of the neck bridge diameter between micron fibers on the stress distribution of the product. Figure 5In the figure, (a), (b) and (c) represent different neck bridging diameters, respectively.

[0060] Depend on Figure 5 It can be seen that increasing the neck bridging diameter between particles can effectively prevent stress concentration at the neck connection. As the neck bridging diameter between aerogel nanoparticles increases, the stress is more evenly distributed in the aerogel composite structure, which can effectively prevent the neck bridging from brittle fracture under stress concentration and cause structural collapse, thereby enhancing the mechanical bearing capacity of the product.

[0061] The present invention relates to a multifunctional integrated fiber-doped aerogel, which realizes multifunctional integration of efficient thermal insulation, high load-bearing capacity and low thermal expansion by combining nanoporous aerogel and fiber-reinforced components. Among them, nanoporous aerogel, based on its unique three-dimensional continuous nanoporous network structure, exhibits extremely low density and thermal conductivity, effectively inhibits gas molecule transmission and thermal bridge formation, significantly reduces heat transfer, and thus efficiently blocks the influence of external heat flow on spacecraft; based on the fact that nanoporous aerogel is composed of a number of aerogel nanoparticles connected, the present invention sets a bonding layer on the surface of nanoporous aerogel to increase the neck bridging diameter between particles, improves the weakness of point contact between particles, effectively prevents stress concentration at the neck connection, and enhances the mechanical bearing capacity of nanoporous aerogel; the fiber-reinforced component is composed of directional arrangement of micron core-shell fibers containing internal inorganic fibers and outer negative thermal expansion layers, which are overlapped with each other. The structure is not only adjustable, but also the negative thermal expansion layer significantly reduces the thermal expansion coefficient of the micron core-shell fibers. According to the thermal protection application requirements of spacecraft in different service environments, the directional arrangement angle and doping density of the micron core-shell fibers can be adjusted to enhance the thermal insulation performance, mechanical strength and thermal stability in a specific direction, thereby significantly improving the comprehensive thermal protection effect of the fiber-doped aerogel and meeting the application requirements of the spacecraft thermal protection system in complex and extreme thermal environments.

[0062] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A multifunctional integrated fiber-doped aerogel, characterized in that: The invention comprises a nanoporous aerogel, a fiber-reinforced component which is arranged in a direction and overlapped with each other in the nanoporous aerogel, and a bonding layer; the raw material of the fiber-reinforced component is micron core-shell fiber; the bonding layer is attached to the outer side of the aerogel nanoparticles constituting the nanoporous aerogel to form a covering layer; The micron core-shell fiber comprises an outer negative thermal expansion layer and an inner inorganic fiber; The negative thermal expansion layer is zirconium tungsten ore and / or scandium gallium oxide; the inorganic fiber is one or more of mullite fiber, quartz fiber, basalt fiber and aluminum silicate fiber; The micron core-shell fiber has an aspect ratio of >2000 and a diameter of 2-20 μm. The inner and outer diameter ratios of the outer negative thermal expansion layer and the inner inorganic fiber are 0-1 and are neither 0 nor 1.

2. The multifunctional integrated fiber-doped aerogel according to claim 1, characterized in that: The fiber reinforcement components are arranged in a directional manner with an orientation angle of 10°-30°.

3. The multifunctional integrated fiber-doped aerogel according to claim 1, characterized in that: The bonding layer raw material includes one or more of epoxy resin, resorcinol-formaldehyde resin and phenolic resin, and the nanoporous aerogel is one or more of silicon dioxide aerogel, zirconium dioxide aerogel and aluminum oxide aerogel.

4. The multifunctional integrated fiber-doped aerogel according to claim 1, characterized in that: The volume content of the adhesive layer in the multifunctional integrated fiber-doped aerogel is 5-10%, and the volume content of the nanoporous aerogel in the multifunctional integrated fiber-doped aerogel is 75-90%.

5. The multifunctional integrated fiber-doped aerogel according to claim 1, characterized in that: The volume content of the fiber-reinforced component in the multifunctional integrated fiber-doped aerogel is 5-20%.

6. A method for preparing the multifunctional integrated fiber-doped aerogel according to any one of claims 1 to 5, characterized in that: The following steps are involved: Directly arranging the fiber-reinforced component, then adding a nanoporous aerogel raw material, performing gelation treatment and aging treatment to form an aerogel composite material containing the fiber-reinforced component; The aerogel composite material containing the fiber-reinforced component is impregnated with the bonding layer solution and cured to obtain the multifunctional integrated fiber-doped aerogel.

7. Use of the multifunctional integrated fiber-doped aerogel according to any one of claims 1 to 5 in thermal insulation materials for aerospace vehicles.

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