A metal-carbon element modified composite aerogel and its preparation method and application

Abstract

The present application specifically discloses a metal-carbon element modified composite aerogel and its preparation method and application. A metal-carbon element modified composite aerogel comprises the following steps: S1, preparing an acid solution containing M metal ions, denoted as solution A; mixing polyvinyl pyrrolidone with deionized water and a two-dimensional material, and ultrasonically treating to obtain solution B; S2, mixing carbon-nitrogen organic material, the solution A, and the solution B to obtain a mixed solution, freeze-drying the mixed solution to obtain a composite aerogel modified by a metal element; S3, mixing the composite aerogel modified by the metal element with a carbon source, and heat-treating in an inert atmosphere to obtain a composite aerogel modified by the metal-carbon element. The present application has the advantages of reducing the density of the absorber, increasing the absorption bandwidth of the absorber, and high controllability.

Description

Technical Field

[0001] The present application relates to the technical field of wave absorbing materials, and in particular to a metal-carbon element modified composite aerogel and a preparation method and application thereof. Background Art

[0002] With the development of the information age, various devices that rely on electromagnetic waves to transmit information have emerged in an endless stream, which brings us convenience while also causing electromagnetic radiation pollution. Electromagnetic absorbing materials can convert incident electromagnetic waves into other forms of energy such as heat, thereby dissipating electromagnetic waves, which plays an important role in reducing electromagnetic radiation pollution. Therefore, the research on electromagnetic absorbing materials has become a research hotspot. In addition, electromagnetic absorbing materials can improve the concealment performance of equipment such as fighter jets, tanks, and warships, thereby improving combat capabilities, which has far-reaching significance for the improvement of my country's national defense strength and the research and development of modern weapons and equipment. Therefore, whether for civilian or military use, the study of absorbing materials is important and necessary.

[0003] However, traditional absorbing materials face a series of problems such as high density, narrow absorption bandwidth and poor controllability, which limits their application in civilian and military fields. There is an urgent need to design an absorbing material that is thin, broadband, high-efficiency and lightweight. Summary of the invention

[0004] In order to solve the problems in the prior art, the present application provides a metal-carbon element modified composite aerogel and a preparation method and application thereof.

[0005] In a first aspect, the present application provides a method for preparing a metal-carbon element modified composite aerogel, using the following technical solution:

[0006] A method for preparing a metal-carbon element modified composite aerogel comprises the following steps:

[0007] S1, preparing an acid solution containing M metal ions, denoted as solution A;

[0008] Mixing polyvinyl pyrrolidone with deionized water and two-dimensional material, and subjecting to ultrasonic treatment to obtain solution B;

[0009] S2, mixing the carbon-nitrogen organic material, the solution A, and the solution B to obtain a mixed solution, and freeze-drying the mixed solution to obtain a composite aerogel modified with a metal element;

[0010] S3, mixing the metal element modified composite aerogel with a carbon source, and performing heat treatment in an inert atmosphere to obtain the metal-carbon element modified composite aerogel.

[0011] In S1, the M metal ions include Fe 3+ , Mn 2+ 、Ni2+ , Cu 2+ 、Zn 2+ The two-dimensional material comprises at least one of graphene and MXene;

[0012] In S2, the carbon-nitrogen organic material includes at least one of chitosan, polypyrrole, and dicyandiamide;

[0013] In S3, the carbon source includes at least one of melamine and dicyandiamide.

[0014] The present application uses two-dimensional materials and carbon-nitrogen organic materials as reaction raw materials to prepare aerogels as wave absorbers, so that the reactants are evenly dispersed at the molecular level in a short time, which is helpful for preparing aerogels with three-dimensional oriented structures; the addition of transition magnetic metals (M metal ions) and carbon elements into the intermediate products with three-dimensional oriented structures can not only enable the aerogels to obtain better impedance matching characteristics, but also allow most electromagnetic waves to enter the aerogels for loss, thereby enhancing the effective absorption bandwidth, and can also enable the aerogels to have multi-interface characteristics, which can effectively enhance the dielectric loss characteristics, so that the aerogels of the present application have multiple loss characteristics such as magnetic loss and dielectric loss. Furthermore, the introduction of carbon elements in S3 can not only increase the number of carbon-based products in the aerogels, improve the conductivity of the aerogels, and help the aerogels to efficiently absorb and attenuate electromagnetic waves, but also the introduction of carbon elements can also generate a continuous three-dimensional network structure in the aerogels, thereby helping to strengthen their lightweight and porous characteristics, which can not only reduce the density of the aerogels (the density of the aerogels prepared by the present invention is approximately 35 mg / cm 3 ), and can further improve the aerogel's microwave absorption and thermal insulation properties.

[0015] Therefore, the aerogel of the present application has the characteristics of achieving low density, broadband electromagnetic wave strong absorption as an absorbing material. In addition, by adjusting the amount of raw materials and the process conditions during the heat treatment process, the composition and conductivity of the aerogel can be effectively changed, thereby effectively regulating the electromagnetic parameters of the aerogel, so that the aerogel can meet the needs of different application scenarios.

[0016] Preferably, in S1, the method for preparing the solution A comprises the following steps: mixing a raw material containing the M metal ions with a weak acid solution to obtain the solution A;

[0017] Wherein, the weak acid solution includes at least one of glacial acetic acid and carbonic acid; the concentration of the weak acid solution is 0.15-0.3 mol / L.

[0018] The weak acid solution in the present invention can dissolve the carbon-nitrogen organic material, allowing it to react with other raw materials, and is helpful for preparing an aerogel with a three-dimensional oriented structure.

[0019] Preferably, in the solution A, the concentration of the M metal ions is 0.015-0.03 mol / L.

[0020] Preferably, the raw material containing the M metal ion includes a metal salt containing the M metal ion and a metal framework organic matter containing the M metal ion.

[0021] By controlling the concentration of M metal ions, the concentration of transition magnetic metal ions doped in the aerogel can be controlled within a reasonable range, which helps the interfaces in the aerogel to cooperate with each other to form a perfect impedance match. Through multiple scattering and strong interface polarization, the aerogel of the present application has excellent electromagnetic wave absorption performance.

[0022] Preferably, in the solution B, the mass ratio of the polyvinyl pyrrolidone, the deionized water, and the two-dimensional material is 4-6:300-500:1-2.

[0023] Preferably, the mass ratio of the carbon-nitrogen organic material to the solution A is 4-8:100-200.

[0024] Preferably, the mass ratio of the solution A to the solution B is 3-5:1-2.

[0025] By controlling the mass ratio of carbon-nitrogen organic material, solution A and solution B, the reaction raw materials are helped to fully react with each other, which not only helps to maintain the porous characteristics and porous orientation consistency of the aerogel, but also helps to form an aerogel with a multi-interface structure, which can effectively improve the impedance matching characteristics and electromagnetic wave loss characteristics of the aerogel.

[0026] Preferably, the mass ratio of the metal element modified composite aerogel to the carbon source is 1:1-2.

[0027] By mixing the composite aerogel modified with metal elements with a carbon source for heat treatment and controlling the amount of carbon source introduced, a sufficient amount of carbon-based products can be generated in the aerogel, and a suitable continuous three-dimensional network structure can be introduced. The combination of the two ensures that the aerogel always maintains its porous properties, which not only helps to improve the conductivity of the aerogel material, but also helps to reduce the density of the aerogel, thereby obtaining an aerogel with light weight and excellent wave-absorbing properties.

[0028] Preferably, during the heat treatment, the temperature is increased to 600-900° C. at a heating rate of 3-7° C. / min and then maintained for 1.5-3 h.

[0029] Preferably, the gas in the inert atmosphere is at least one of nitrogen and helium.

[0030] By adjusting the appropriate temperature gradient and controlling the reaction temperature, it is helpful to generate a uniform and uniformly oriented porous structure in the aerogel, which helps to obtain aerogel with low density, low filling ratio and strong absorption.

[0031] In a second aspect, the present application provides a metal-carbon element modified composite aerogel, which adopts the following technical solution:

[0032] A metal-carbon element modified composite aerogel is prepared by any of the methods described above.

[0033] In a second aspect, the present application provides an application of a metal-carbon element modified composite aerogel in the field of wave absorption, using the following technical solution:

[0034] The invention discloses an application of a metal-carbon element modified composite aerogel in the field of wave absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a SEM image of the metal-carbon element modified composite aerogel prepared in Example 1, wherein: Figure 1 Figure a is a cross-sectional morphology diagram. Figure 1 Figure b is a longitudinal section morphology image.

[0036] Figure 2 This is a locally enlarged SEM image of the metal-carbon element modified composite aerogel prepared in Example 1.

[0037] Figure 3 This is the XRD pattern of the metal-carbon element modified composite aerogel prepared in Example 1.

[0038] Figure 4 This is the reflection loss spectrum of the metal-carbon element modified composite aerogel prepared in Example 1.

[0039] Figure 5 This is the reflection loss spectrum of the metal-carbon element modified composite aerogel prepared in Example 2. DETAILED DESCRIPTION

[0040] For better understanding and implementation, the technical solution of the present application will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0042] Unless otherwise indicated, all numerical values ​​expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that can vary depending upon the desired properties desired to be obtained.

[0043] As used herein, "and / or" means one or all of the mentioned elements.

[0044] As used herein, “including” and “comprising” encompasses the case where only the stated elements are present as well as the case where there are other elements other than the stated elements.

[0045] All percentages in this application are by weight unless otherwise stated.

[0046] Unless otherwise indicated, "a", "an", "an" and "the" used in this specification are intended to include "at least one" or "one or more". For example, "a component" means one or more components, so more than one component may be considered and may be employed or used in the implementation of the embodiment.

[0047] Example 1

[0048] 1. A method for preparing a metal-carbon element modified composite aerogel, comprising the following steps:

[0049] S1, dissolve 1.5g manganese chloride and 1.9g ferric chloride in 120mL 0.2mol / L glacial acetic acid, recorded as solution A;

[0050] 500 mg of polyvinyl pyrrolidone was dissolved in 40 mL of deionized water, and 200 mg of graphene was added, and ultrasonic treatment was performed for 1 h to form solution B;

[0051] S2, adding 4 g of chitosan (dropping speed of 1 g / 15 min) to the above solution A, and then mixing with the above solution B to obtain a mixed solution, first precooling the above mixed solution at -50°C for 30 min, and then freeze-drying it at -60°C in a vacuum state for 60 h to obtain a composite aerogel modified with metal elements;

[0052] S3, mixing the above-mentioned metal element modified composite aerogel with melamine in a mass ratio of 1:1, heat treating in a nitrogen atmosphere, setting the heating rate to 5°C / min until the temperature rises to 750°C, and keeping the temperature for 2h, thereby obtaining a metal-carbon element modified composite aerogel.

[0053] The SEM image of the metal-carbon element modified composite aerogel prepared in this example is as follows: Figure 1 and Figure 2The XRD test diagram of the metal-carbon element modified composite aerogel prepared in this embodiment is shown in Figure 3 As shown; the reflection loss spectrum of the metal-carbon element modified composite aerogel prepared in this embodiment is as shown Figure 4 shown.

[0054] 2. Preparation of Absorbing Materials

[0055] The silica gel and the curing agent in a mass ratio of 100:1 were uniformly stirred in a beaker, and then the aerogel was immersed in the mixture under vacuum assistance. Subsequently, the fully filled sample was cured in an oven at 60° C. for 4 hours to obtain an absorbing material.

[0056] Example 2

[0057] 1. A method for preparing a metal-carbon element modified composite aerogel, comprising the following steps:

[0058] S1, dissolve 1.5g manganese chloride and 1.9g ferric chloride in 120mL 0.2mol / L glacial acetic acid, recorded as solution A;

[0059] 500 mg of polyvinyl pyrrolidone was dissolved in 40 mL of deionized water, and 200 mg of graphene was added, and ultrasonic treatment was performed for 1 h to form solution B;

[0060] S2, adding 4 g of chitosan (dropping speed of 1 g / 15 min) to the above solution A, and then mixing with the above solution B to obtain a mixed solution, first precooling the above mixed solution at -50°C for 30 min, and then freeze-drying it at -60°C in a vacuum state for 60 h to obtain a composite aerogel modified with metal elements;

[0061] S4, mixing the above-mentioned metal element modified composite aerogel with melamine in a mass ratio of 1:1, heat treating in a nitrogen atmosphere, setting the heating rate to 5°C / min until the temperature rises to 850°C, and keeping the temperature for 2h, thereby obtaining a metal-carbon element modified composite aerogel.

[0062] The reflection loss spectrum of the metal-carbon element modified composite aerogel prepared in this example is as follows: Figure 5 shown.

[0063] 2. Preparation of Absorbing Materials

[0064] The silica gel and the curing agent in a mass ratio of 100:1 were uniformly stirred in a beaker, and then the aerogel was immersed in the mixture under vacuum assistance. Subsequently, the fully filled sample was cured in an oven at 60° C. for 4 hours to obtain an absorbing material.

[0065] Example 3

[0066] 1. A method for preparing a metal-carbon element modified composite aerogel, comprising the following steps:

[0067] S1, dissolve 1.5g manganese chloride and 1.9g nickel chloride in 120mL carbonic acid with a concentration of 0.15mol / L, recorded as solution A;

[0068] 450 mg of polyvinyl pyrrolidone was dissolved in 31 mL of deionized water, and 180 mg of MXene was added and ultrasonicated for 0.8 h to form solution B;

[0069] S2, adding 6 g of chitosan (dropping speed of 1 g / 15 min) to the above solution A, and then mixing with the above solution B to obtain a mixed solution, first precooling the above mixed solution at -50°C for 30 min, and then freeze-drying it at -60°C in a vacuum state for 55 h to obtain a composite aerogel modified with metal elements;

[0070] S4, mixing the above-mentioned metal element modified composite aerogel with melamine in a mass ratio of 1:2, heat treating in a nitrogen atmosphere, setting the heating rate to 3°C / min until the temperature rises to 600°C, and keeping the temperature for 3 hours, thereby obtaining a metal-carbon element modified composite aerogel.

[0071] 2. Preparation of Absorbing Materials

[0072] The silica gel and the curing agent in a mass ratio of 100:1 were uniformly stirred in a beaker, and then the aerogel was immersed in the mixture under vacuum assistance. Subsequently, the fully filled sample was cured in an oven at 60° C. for 4 hours to obtain an absorbing material.

[0073] Example 4

[0074] 1. A method for preparing a metal-carbon element modified composite aerogel, comprising the following steps:

[0075] S1, dissolve 1.5g copper chloride and 1.9g nickel chloride in 120mL carbonic acid with a concentration of 0.3mol / L, recorded as solution A;

[0076] 550 mg of polyvinyl pyrrolidone was dissolved in 50 mL of deionized water, and 220 mg of MXene was added and ultrasonicated for 1.2 h to form solution B;

[0077] S2, adding 5 g of dicyandiamide (dropping speed of 1 g / 15 min) to the above solution A, and then mixing with the above solution B to obtain a mixed solution, first precooling the above mixed solution at -20°C for 30 min, and then freeze-drying it at -70°C in a vacuum state for 40 h to obtain a composite aerogel modified with metal elements;

[0078] S4, mixing the above-mentioned metal element modified composite aerogel with melamine in a mass ratio of 1:1.6, and heat treating it in a helium atmosphere, setting the heating rate to 7°C / min until the temperature rises to 900°C, and keeping it warm for 1.5h, thereby obtaining a metal-carbon element modified composite aerogel.

[0079] 2. Preparation of Absorbing Materials

[0080] The silica gel and the curing agent in a mass ratio of 100:1 were uniformly stirred in a beaker, and then the aerogel was immersed in the mixture under vacuum assistance. Subsequently, the fully filled sample was cured in an oven at 60° C. for 4 hours to obtain an absorbing material.

[0081] Example 5

[0082] 1. A method for preparing a metal-carbon element modified composite aerogel, comprising the following steps:

[0083] S1, dissolve 1.5g zinc chloride and 1.9g nickel chloride in 120mL carbonic acid with a concentration of 0.25mol / L, recorded as solution A;

[0084] 520 mg of polyvinyl pyrrolidone was dissolved in 35 mL of deionized water, and 210 mg of MXene was added and ultrasonicated for 1 h to form solution B;

[0085] S2, adding 4 g polypyrrole (dropping speed of 1 g / 15 min) to the above solution A, and then mixing with the above solution B to obtain a mixed solution, first precooling the above mixed solution at -196°C for 30 min, and then freeze-drying it at -50°C in a vacuum state for 72 h to obtain a composite aerogel modified with metal elements;

[0086] S3, mixing the above-mentioned metal element modified composite aerogel with melamine in a mass ratio of 1:1.2, heat treating in a helium atmosphere, setting the heating rate to 7°C / min until the temperature rises to 700°C, and keeping the temperature for 2h, thereby obtaining a metal-carbon element modified composite aerogel.

[0087] 2. Preparation of Absorbing Materials

[0088] The silica gel and the curing agent in a mass ratio of 100:1 were uniformly stirred in a beaker, and then the aerogel was immersed in the mixture under vacuum assistance. Subsequently, the fully filled sample was cured in an oven at 60° C. for 4 hours to obtain an absorbing material.

[0089] Example 6

[0090] The difference between this embodiment and embodiment 1 is that the heating rate during the heat treatment process is 10°C / min, and the temperature is heated to 1000°C and then kept warm for 1 hour; other steps and parameter settings are consistent with embodiment 1.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 1 is that FeSiAl@C of equal weight is used to replace the metal-carbon element modified composite aerogel in the absorbing material in Example 1.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 1 is that solution A does not contain Fe 3+ , Mn 2+ ; Other steps and parameter settings are consistent with Example 1.

[0095] Comparative Example 3

[0096] The difference between this comparative example and Example 1 is that the graphene in solution B is replaced by carbon nanotubes of equal weight; the other steps and parameter settings are consistent with those in Example 1.

[0097] Comparative Example 4

[0098] The difference between this comparative example and Example 1 is that no carbon source is used in the heat treatment process of S4; other steps and parameter settings are consistent with Example 1.

[0099] Test Method

[0100] 1. SEM morphology test

[0101] The morphology and microstructure of the aerogels prepared in the above examples and comparative examples were measured using a Sigma 300 scanning electron microscope (SEM) at an accelerating voltage of 5 kV.

[0102] 2. XRD test

[0103] The aerogels prepared in the above examples and comparative examples were tested using an Ultima IV X-ray diffractometer (XRD).

[0104] 3. Wave absorption performance test

[0105] The aerogels prepared in the above embodiments and comparative examples were immersed in molten paraffin, and vacuum was drawn to make them completely wetted. The aerogels were then taken out, and the paraffin was completely solidified. A coaxial ring sample with an outer diameter of 7.00 mm and an inner diameter of 3.04 mm was made into a mold, and then its electromagnetic parameters were tested with a vector network analyzer (model ZNA43, Rohde & Schwarz, Germany). According to the transmission line theory, the wave absorbing performance of the aerogel was obtained.

[0106] 4. Density test

[0107] The density of the aerogels in Examples 1-3 was tested by the conventional water displacement method; first, the weight was measured, then the corresponding volume was measured by the water displacement method, and the corresponding bulk density was calculated.

[0108] Table 1

[0109]

[0110] Combined with Examples 1-5, Comparative Examples 1-4, Table 1 and Figure 1-Figure 5 It can be seen that in the present application, by using metal elements and carbon elements to modify the aerogel with a three-dimensional directional porous structure formed by two-dimensional materials and carbon-nitrogen organic materials, multi-interface characteristics can be formed in the aerogel, which helps the aerogel to obtain excellent impedance matching characteristics, enhance its dielectric loss characteristics and increase the effective absorption band width. Furthermore, the introduction of carbon elements can also help increase the number of carbon-based products in the aerogel structure and increase the number of its porous structures, which can not only reduce the density of the aerogel, but also further enhance its absorbing performance.

[0111] Combining Examples 1 and 6 with Table 1, it can be seen that when the temperature is too high, the porous structure of the aerogel is easily destroyed, and at the same time, its conductivity is too high, which will be detrimental to improving the overall impedance matching characteristics of the material, and ultimately lead to a decrease in the performance of the aerogel. By controlling the heat treatment temperature rise rate and the heat treatment temperature in S3 within a suitable range, it is helpful for the carbon source to generate a sufficient amount of carbon-based products in the aerogel and ensure the orientation consistency of the porous structure generated in the aerogel, which helps to reduce the density of the aerogel and enhance the electromagnetic loss characteristics of the aerogel.

[0112] The above embodiments are only used to illustrate the technical solution of the present application rather than to limit the protection scope of the present application. Although the present application is described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the technical solution of the present application can be modified or equivalently replaced, but these modifications or replacements are all within the protection scope of the present application.

Claims

1. A method for preparing a metal-carbon element modified composite aerogel, characterized in that: The steps include: S1, preparing an acid solution containing M metal ions, denoted as solution A; mixing polyvinyl pyrrolidone with deionized water and two-dimensional material, and subjecting to ultrasonic treatment to obtain solution B; S2, mixing the carbon-nitrogen organic material, the solution A, and the solution B to obtain a mixed solution, and freezing the mixed solution to obtain a composite aerogel modified with a metal element; S3, mixing the metal element modified composite aerogel with a carbon source, and performing heat treatment in an inert atmosphere to obtain the metal-carbon element modified composite aerogel; In S1, the M metal ions include Fe 3+ , Mn 2+ 、Ni 2+ , Cu 2+ 、Zn 2+ The two-dimensional material comprises at least one of graphene and MXene; In S2, the carbon-nitrogen organic material includes at least one of chitosan, polypyrrole, and dicyandiamide; In S3, the carbon source includes at least one of melamine and dicyandiamide; and the mass ratio of the metal element modified composite aerogel to the carbon source is 1:(1-2).

2. The method for preparing the metal-carbon element modified composite aerogel according to claim 1, characterized in that: In S1, the method for preparing the solution A comprises the following steps: mixing a raw material containing the M metal ions with a weak acid solution to obtain the solution A; Wherein, the weak acid solution includes at least one of glacial acetic acid and carbonic acid; the concentration of the weak acid solution is 0.15-0.3 mol / L.

3. The method for preparing the metal-carbon element modified composite aerogel according to claim 1, characterized in that: In the solution A, the concentration of the M metal ions is 0.015-0.03 mol / L.

4. The method for preparing the metal-carbon element modified composite aerogel according to claim 1, characterized in that: In the solution B, the mass ratio of the polyvinyl pyrrolidone, the deionized water, and the two-dimensional material is (4-6): (300-500): (1-2).

5. The method for preparing the metal-carbon element modified composite aerogel according to claim 1, characterized in that: The mass ratio of the carbon-nitrogen organic material to the solution A is (4-8): (100-200).

6. The method for preparing the metal-carbon element modified composite aerogel according to claim 5, characterized in that: The mass ratio of the solution A to the solution B is (3-5):(1-2).

7. The method for preparing the metal-carbon element modified composite aerogel according to any one of claims 1 to 6, characterized in that: During the heat treatment process, the temperature is raised to 600-900°C at a rate of 3-7°C / min and then kept at this temperature for 1.5-3h.

8. A metal-carbon element modified composite aerogel, characterized in that: Prepared according to any one of claims 1 to 7.

9. Application of the metal-carbon element modified composite aerogel as claimed in claim 8 in the field of microwave absorption.

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