Preparation method of light high-strength super-hydrophobic carbon foamate / SiO2 composite aerogel and application of light high-strength super-hydrophobic carbon foamate / SiO2 composite aerogel in icing prevention / microwave absorption

Abstract

The invention discloses a preparation method of light high-strength super-hydrophobic carbon foam / SiO2 composite aerogel and application of the light high-strength super-hydrophobic carbon foam / SiO2 composite aerogel in icing prevention / microwave absorption. The preparation method comprises the following steps: by taking foamy carbon as a structural reinforcement, completely impregnating SiO2 sol into pores of the foamy carbon through vacuum impregnation, and then carrying out gelation, aging, replacement and normal-pressure drying to construct the light high-strength super-hydrophobic carbon foam SiO2 composite aerogel with the interpenetrating phase structure. The material has excellent compressive strength, anti-icing performance (21s rapid deicing performance under low voltage of 2V and ultra-long anti-icing time) and electromagnetic wave absorption characteristic, and dual-interface polarization formed by foamy carbon and SiO2 aerogel enables the minimum reflection loss of the composite aerogel to reach-22.6 dB and the absorption bandwidth to reach 4.48 GHz. The composite aerogel maintains the original structure and contact angle after multiple times of mechanical wear, the water contact angle is as high as 158.3 degrees, and the rolling angle is as low as 4.9 degrees.

Description

Technical Field

[0001] This invention belongs to the field of multifunctional aerogel materials, specifically a method for preparing a lightweight, high-strength, superhydrophobic carbon foam / SiO2 composite aerogel and its application in anti-icing / microwave absorption. Background Technology

[0002] With the rapid development and increasing maturity of communication technologies, while bringing convenience to our communications, they have also brought about very serious electromagnetic radiation pollution, severely threatening the safe and stable operation of many critical facilities and equipment, especially in extremely cold environments. To reduce the damage to critical facilities and equipment caused by electromagnetic radiation and cold environments, it is necessary to develop new multifunctional integrated composite materials. Anti-icing / microwave absorbing composite materials possess excellent anti-icing performance and microwave absorption capabilities. Furthermore, their durability and cost-effectiveness, such as lightweight design, high strength, stability, and weather resistance, must also be considered, which is of great significance for industrialization and application.

[0003] Compared to traditional electromagnetic wave absorbing and anti-icing materials, carbon foam composite SiO2 aerogel possesses advantages such as low density, high strength, strong weather resistance, high stability, high electromagnetic wave absorption capacity, and excellent anti-icing / de-icing capabilities, making it one of the most promising anti-icing / electromagnetic wave absorbing materials currently available. Utilizing the excellent porous properties and functional components of carbon foam, the introduction of functional SiO2 aerogel can maintain the functionality of carbon foam while also imparting superhydrophobic properties, thereby endowing it with anti-icing properties. However, traditional anti-icing / microwave absorbing materials suffer from complex synthesis methods, poor stability, weak functionality, poor weather resistance, and high cost, and it is difficult to amplify their performance through precise structural control. This results in insufficient anti-icing and electromagnetic wave absorption performance, limiting their practical applications.

[0004] There are already relevant studies, for example, Chinese invention patent publication number CN119798773A discloses a multifunctional flexible composite aerogel with electro-thermal de-icing, anti-icing and microwave absorption and its preparation method, which mainly involves the uniform and tight bonding of flexible silica aerogel to flexible nickel. The copper-polyurethane conductive sponge framework allows the flexible composite aerogel to retain excellent flexibility and structural stability. This also enables the flexible composite aerogel to possess de-icing and anti-icing properties, as well as microwave absorption properties.

[0005] However, the multifunctional flexible composite aerogel obtained by this method has a large matrix flexibility and low compressive strength, making it unsuitable for high-stress environments; it relies on continuous power supply, resulting in high energy consumption; and polyurethane has poor UV and salt spray resistance and is prone to aging. Therefore, there is an urgent need to develop a multifunctional composite aerogel that is "lightweight, high-strength, superhydrophobic, low-energy, and structurally stable" to meet the pressing needs of aerospace, communication base stations, and other extreme environments for lightweight, high-strength anti-icing / microwave absorbing materials.

[0006] Chinese invention patent publication number CN109678557A discloses a water glass-based SiO2 aerogel / carbon foam composite insulation material, which mainly consists of a carbon foam reinforcement and water glass-based SiO2 aerogel, processed through a sol-gel process. SiO2 aerogel / carbon foam composite insulation materials were prepared by gelation and atmospheric pressure drying. This resulted in composite materials with certain thermal insulation properties and mechanical strength. However, the composite insulation materials obtained by this method still suffer from low mechanical strength and limited functionality.

[0007] To enable reliable application of materials under extreme stress environments, it is urgent to develop lightweight, high-strength, multifunctional integrated superhydrophobic anti-icing microwave absorbing materials. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method for preparing lightweight, high-strength, superhydrophobic carbon foam / SiO2 composite aerogel and its application in anti-icing / microwave absorption.

[0009] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A method for preparing a lightweight, high-strength, superhydrophobic carbon foam / SiO2 composite aerogel includes the following steps: (1) The silicon source precursor, surfactant and water are mixed in a mass ratio of 10-20:0.1-0.2:25-35 to obtain SiO2 sol; (2) Place the carbon foam in the SiO2 sol and vacuum impregnate for 0.5 to 1.5 h; (3) Then the pH of the system was adjusted to 7-11 with an alkaline catalyst and gelled at 35-45 °C for 0.5-2.5 h; (4) Then, the product is aged in a water bath at 35-45 ℃ for 12-24 h, replaced with anhydrous ethanol at 60-80 ℃ for 72-96 h, and dried at normal pressure at 60-90 ℃ to obtain the final product.

[0010] In the above preparation method, further, in step (1), the silicon source precursor is one or a mixture of several of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane.

[0011] Furthermore, in step (1), the surfactant is one or a mixture of several of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and dodecyltrimethylammonium bromide.

[0012] Furthermore, in step (2), the carbon foam is at least one of mesh glass carbon foam and graphitized carbon foam.

[0013] Furthermore, in step (3), the alkaline catalyst is at least one of ammonia and urea.

[0014] Based on a general inventive concept, the present invention also provides a lightweight, high-strength, superhydrophobic carbon foam / SiO2 composite aerogel obtained by the above preparation method, which has a three-dimensional porous carbon foam and SiO2 aerogel filling the pores inside the carbon foam; the volume percentage of carbon foam in the composite aerogel is 2-6%.

[0015] The aforementioned lightweight, high-strength, superhydrophobic carbon foam / SiO2 composite aerogel further has a density of 0.121–0.147 g / cm³. 3 The water contact angle is 150–159°, the roll-off angle is 3.2–9.7°, and the compressive strength at 40% strain is 1.5–2 MPa; the thermal conductivity of the composite aerogel is 0.215–0.294 W / mK.

[0016] Based on a general inventive concept, the present invention also provides the application of a lightweight, high-strength, superhydrophobic carbon foam / SiO2 composite aerogel in anti-icing and / or microwave absorption.

[0017] Further, the composite aerogel, in the form of prefabricated functional skins or modular patches, is applied to aircraft / UAV wings, helicopter rotors, engine air inlet leading edges, or radar communication base stations. The superhydrophobic surface of the composite aerogel passively delays icing; when icing occurs, electricity is applied to actively and rapidly de-ic the carbon network using Joule heating; simultaneously, its microwave absorption properties can reduce radar scattering signals in these critical areas, improving stealth performance.

[0018] Furthermore, when the composite aerogel is used for anti-icing or microwave absorption, the anti-icing performance meets the following requirements: de-icing is completed within 21 s under a 2V DC voltage, and the anti-icing time is ≥800 s under -10 ℃ and RH 80% conditions; the microwave absorption performance meets the following requirements: minimum reflection loss ≤-22.6 dB within 2~18 GHz, and effective absorption bandwidth ≥4.4 GHz.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel of the present invention has a three-dimensional porous bicomponent interpenetrating phase structure, which maintains an extremely low density (0.121~0.147 g / cm³). 3 While possessing excellent superhydrophobic properties (water contact angle 150–159°, roll-off angle 3.2–9.7°), it significantly improves the mechanical strength of the material (compressive strength 1.5–2 MPa under 40% strain conditions) while maintaining low density. This overcomes the shortcomings of traditional aerogels, such as high brittleness, and the problem of low mechanical strength of flexible materials, making it a promising material for high-stress environments.

[0020] 2. The lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel of the present invention has good thermal insulation properties (thermal conductivity 0.215-0.294 W / mK).

[0021] 3. The superhydrophobic properties of this invention endow the composite aerogel with excellent anti-icing properties, enabling it to achieve rapid de-icing performance of 21 seconds at a low voltage of 2 V, which is energy-saving and efficient; it can also effectively delay icing, and has an ultra-long anti-icing time of 803 seconds in actual anti-icing environments; at the same time, the composite aerogel also has both dielectric loss and structural loss mechanisms, exhibiting excellent electromagnetic wave absorption performance, with a minimum reflection loss of -22.6 dB and an effective absorption bandwidth of 4.48 GHz.

[0022] 4. The process of this invention is simple, using atmospheric pressure drying, which avoids the high cost and high risk of supercritical drying, and is more conducive to large-scale production; the resulting material integrates multiple functions such as lightweight, high strength, hydrophobicity, anti-icing, and wave absorption, and has broad application prospects in extreme environment fields such as aerospace and electronic communication. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel structure of the present invention; where 1 is carbon foam and 2 is SiO2 aerogel.

[0025] Figure 2 The diagram shows the structure of the carbon foam-SiO2 composite aerogel prepared in comparison; where 10 represents carbon foam, 20 represents SiO2 aerogel, and 30 represents pores. Detailed Implementation

[0026] This invention provides a method for preparing a lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel and its application in anti-icing / microwave absorption. The method for preparing the lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel includes the following steps in sequence: (1) A silicon source precursor, a surfactant and deionized water are mixed to obtain a SiO2 sol; The silicon source precursor is one or a mixture of several of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane; the surfactant is one or a mixture of several of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and dodecyltrimethylammonium bromide; the mass ratio of silicon source precursor, surfactant, and deionized water is 10-20:0.1-0.2:25-35; (2) The carbon foam is placed in the SiO2 sol and impregnated to obtain the impregnated carbon foam; the carbon foam is one of the reticulated glass carbon foam and graphitized carbon foam; (3) The pH value of the SiO2 sol in the impregnated carbon foam is adjusted to alkaline using an alkaline catalyst, and the mixture is allowed to stand for gelation to obtain a carbon foam composite material completely filled with SiO2 gel; the alkaline catalyst is one or a mixture of ammonia and urea. (4) The carbon foam composite material completely filled with SiO2 gel is subjected to aging, displacement and normal pressure drying treatment. The displacement is carried out by anhydrous ethanol at 60°C for 72 hours. The drying temperature is 60-90°C and the drying pressure is normal pressure. The lightweight high-strength superhydrophobic carbon foam / SiO2 composite aerogel is obtained.

[0027] The prepared lightweight, high-strength, superhydrophobic carbon foam-SiO2 composite aerogel comprises a carbon foam with a three-dimensional through-pore structure and a SiO2 aerogel tightly filled in situ within the through-pores of the carbon foam; wherein the volume percentage of the carbon foam is 2–6%; and the density of the composite aerogel is 0.121–0.147 g / cm³. 3 The water contact angle is 150–159°, the roll-off angle is 3.2–9.7°, the compressive strength under 40% strain is 1.5–2 MPa, and the thermal conductivity is 0.215–0.294 W / mK.

[0028] This invention provides an application of lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel in anti-icing and / or microwave absorption. The introduction of carbon foam not only enhances the mechanical strength of the SiO2 aerogel and improves its compressive strength, but also broadens its electromagnetic wave absorption and electrothermal de-icing properties, thus functionalizing its inherent anti-icing properties. Furthermore, this carbon foam-reinforced SiO2 aerogel composite material maintains its lightweight, thermal insulation, multifunctionality, and wear resistance, while also possessing the advantages of being cut to fit complex irregular shapes, enhancing its application in complex shapes.

[0029] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0030] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0031] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0032] In this invention, the "40% strain condition" refers to a specific mechanical state when the ratio of the thickness reduction (ΔH) of the composite aerogel sample to its original initial thickness (H0) reaches 40% under unidirectional quasi-static compression along its thickness direction. This parameter is a dimensionless quantity, calculated as: strain (ε) = (compressed thickness H - initial thickness H0) / initial thickness H0 = -40%. Under this state, the real-time thickness of the sample is 60% of its initial thickness. The "RH 80% condition" refers to the percentage of the actual water vapor density (denoted by d1) per unit volume of air to the saturated water vapor density (denoted by d2) at the same temperature, i.e., RH (%) = d1 / d2 × 100%.

[0033] Example 1: A lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel, such as Figure 1 The composite aerogel is composed of carbon foam 1 with a three-dimensional porous structure and SiO2 aerogel 2 completely filling the pores inside the carbon foam. The preparation method of the composite aerogel includes the following steps: (1) Prepare SiO2 sol by mixing methyltrimethoxysilane, surfactant, and deionized water in a mass ratio of 15:0.15:30; the surfactant is hexadecyltrimethylammonium bromide; (2) The carbon foam is immersed in SiO2 sol and vacuum impregnated for 1 hour; the carbon foam is a network glassy carbon. (3) After impregnation, the pH value is adjusted to 10 with ammonia water to gel, age and replace; the gel is placed in 35℃ for 2 hours, the aging is placed in a water bath at 35℃ for 12 hours, and the replacement is carried out with anhydrous ethanol for 72 hours; after replacement, it is placed in 90℃ for normal pressure drying to form a lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel.

[0034] Testing revealed that the lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel of this embodiment contains 3.4% carbon foam by volume and has a density of 0.134 g / cm³. 3 It has a water contact angle of 155.3°, a roll-off angle of 6.2°, and a thermal conductivity of 0.268 W / mK. Its mechanical strength test results are as follows: 1.64 MPa under 40% strain. It exhibits rapid de-icing performance in 21 seconds at a low voltage of 2 V and an ultra-long anti-icing time of 803 seconds in actual anti-icing environments. Its minimum reflection loss in electromagnetic wave absorption reaches -22.6 dB, and its absorption bandwidth reaches 4.48 GHz.

[0035] Example 2: A lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel, such as Figure 1 The composite aerogel is composed of carbon foam 1 with a three-dimensional porous structure and SiO2 aerogel 2 completely filling the pores inside the carbon foam. The preparation method of the composite aerogel includes the following steps: (1) Prepare SiO2 sol by mixing methyltrimethoxysilane, surfactant, and deionized water in a mass ratio of 15:0.15:30; the surfactant is hexadecyltrimethylammonium chloride; (2) The carbon foam is immersed in SiO2 sol and vacuum impregnated for 1 hour; the carbon foam is a network glassy carbon. (3) After impregnation, the pH value is adjusted to 10 with ammonia water to gel, age and replace; the gel is placed in 35℃ for 2 hours, the aging is placed in a water bath at 35℃ for 12 hours, and the replacement is carried out with anhydrous ethanol for 72 hours; after replacement, it is placed in 90℃ for normal pressure drying to form a lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel.

[0036] Testing revealed that the lightweight, high-strength, superhydrophobic carbon foam SiO2 composite aerogel of this embodiment contains 3.4% carbon foam by volume and has a density of 0.126 g / cm³. 3It has a water contact angle of 154.8°, a roll-off angle of 5.9°, and a thermal conductivity of 0.274 W / mK. Its mechanical strength test results are as follows: 1.52 MPa under 40% strain. It exhibits rapid de-icing performance in 25 seconds at a low voltage of 2 V and an ultra-long anti-icing time of 812 seconds in actual anti-icing environments. Its minimum reflection loss in electromagnetic wave absorption reaches -21.4 dB, and its absorption bandwidth reaches 4.12 GHz.

[0037] Comparative Example 1: A prior art carbon foam SiO2 composite aerogel differs from Example 1 only in the ratio of methyltrimethoxysilane to deionized water, and is not included in the scope of Example 1. Specifically, the SiO2 sol is prepared by mixing methyltrimethoxysilane, surfactant, and deionized water at a mass ratio of 5:0.15:40; the surfactant is hexadecyltrimethylammonium bromide. Everything else is the same as in Example 1.

[0038] The composite aerogel prepared in this comparative example exhibits a discrete particle distribution within the carbon foam framework due to aerogel shrinkage. Figure 2 As shown, it may lack structural stability and application performance.

[0039] Comparative analysis reveals that the composite aerogel of this invention has the following advantages. By ensuring that the aerogel does not shrink, it possesses excellent mechanical strength. Combined with the mechanical strength of carbon foam, the prepared composite material exhibits even better mechanical properties. Furthermore, the low density of both the aerogel and carbon foam ensures that the composite material retains its low density. The combination of these two elements endows the material with anti-icing properties and electromagnetic wave absorption properties.

[0040] Comparative Example 2: A prior art carbon foam SiO2 composite aerogel differs from Example 1 only in the replacement conditions. In Example 1, deionized water was used for replacement for 72 hours; all other conditions were the same. When this replacement method is not used, the prepared aerogel exhibits significant shrinkage characteristics, resulting in a discrete particle distribution within the carbon foam framework, as... Figure 2 As shown, it may lack structural stability and application performance.

[0041] Comparative analysis reveals that the composite aerogel of this invention has the following advantages. By ensuring that the aerogel does not shrink, it possesses excellent mechanical strength. Combined with the mechanical strength of carbon foam, the prepared composite material exhibits even better mechanical properties. Furthermore, the low density of both the aerogel and carbon foam ensures that the composite material retains its low density. The combination of these two elements endows the material with anti-icing properties and electromagnetic wave absorption properties.

Claims

1. A method for preparing a lightweight, high-strength, superhydrophobic carbon foam / SiO2 composite aerogel, characterized in that, Includes the following steps: (1) The silicon source precursor, surfactant and water are mixed in a mass ratio of 10-20:0.1-0.2:25-35 to obtain SiO2 sol; (2) Place the carbon foam in the SiO2 sol and vacuum impregnate for 0.5 to 1.5 h; (3) Then the pH of the system was adjusted to 7-11 with an alkaline catalyst and gelled at 35-45 °C for 0.5-2.5 h. (4) Then, the mixture is aged in a water bath at 35-45 ℃ for 12-24 h, replaced with anhydrous ethanol at 60-80 ℃ for 72-96 h, and dried at normal pressure at 60-90 ℃ to obtain the final product.

2. The preparation method according to claim 1, characterized in that, In step (1), the silicon source precursor is one or a mixture of several of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane.

3. The preparation method according to claim 1, characterized in that, In step (1), the surfactant is one or a mixture of several of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and dodecyltrimethylammonium bromide.

4. The preparation method according to claim 1, characterized in that, In step (2), the carbon foam is at least one of mesh glass carbon foam and graphitized carbon foam.

5. The preparation method according to claim 1, characterized in that, In step (3), the alkaline catalyst is at least one of ammonia and urea.

6. A lightweight, high-strength, superhydrophobic carbon foam / SiO2 composite aerogel obtained by any one of the preparation methods of claims 1 to 5, characterized in that, It has a three-dimensional through-pore structure of carbon foam and SiO2 aerogel that is tightly filled in situ within the through-pores of carbon foam; wherein the volume percentage of carbon foam is 2 to 6%.

7. The composite aerogel according to claim 6, characterized in that, The density of the composite aerogel is 0.121–0.147 g / cm³. 3 The water contact angle is 150–159°, the roll-off angle is 3.2–9.7°, and the compressive strength under 40% strain conditions is 1.5–2 MPa; the thermal conductivity of the composite aerogel is 0.215–0.294 W / mK.

8. The application of the lightweight, high-strength, superhydrophobic carbon foam / SiO2 composite aerogel obtained by any one of the preparation methods in claims 1 to 5 in anti-icing and / or microwave absorption.

9. The application according to claim 8, characterized in that, The composite aerogel is applied to aircraft / UAV wings, helicopter rotors, engine air inlet leading edges, or radar communication base stations in the form of prefabricated functional skins or modular patches.

10. The application according to claim 9, characterized in that, When the composite aerogel is used in anti-icing or microwave absorption, its anti-icing performance meets the following requirements: de-icing is completed within 21 seconds under a 2 V DC voltage, and the anti-icing time is ≥800 seconds under -10 ℃ and RH 80% conditions. The microwave absorption performance meets the following requirements: minimum reflection loss ≤ -22.6 dB within the range of 2 to 18 GHz, and effective absorption bandwidth ≥ 4.4 GHz.

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