Preparation method of wave-absorbing agent capable of being coated at room temperature

Abstract

The invention discloses a preparation method of a wave-absorbing agent capable of being coated at room temperature, and belongs to the field of electromagnetic wave absorbing materials.The preparation method comprises the steps that a ceramic glass-carbon-based material is subjected to protective atmosphere heat treatment and then subjected to air atmosphere treatment, and a ceramic glass system coated carbon composite wave-absorbing material is obtained; uniformly mixing magnesium silicate, a sodium silicate solution, silicon dioxide and magnesium oxide to prepare a composite binder; and uniformly stirring the ceramic glass system coated carbon composite wave-absorbing material and a composite binder to obtain the wave-absorbing agent capable of being coated at room temperature. The wave-absorbing agent capable of being coated at the room temperature can solve the problem of limitation existing when an existing wave-absorbing material is used in multiple application scenes.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic wave absorbing materials, and particularly to a preparation method of a wave-absorbing agent that can be coated at room temperature. Background Art

[0002] With the rapid development of aerospace technology, the stealth performance of aircraft has become an important indicator of modern military equipment. In the design of hypersonic aircraft, the materials on the body surface must have excellent electromagnetic wave absorption ability to reduce the probability of being detected by the enemy's detection system. However, the materials on the aircraft surface need to withstand extreme aerodynamic heating during high-speed flight, and at the same time, they also need to resist the performance degradation caused by high temperature and oxidation. Therefore, it is particularly important to develop electromagnetic wave absorbing coatings for high-temperature applications.

[0003] Traditional electromagnetic wave absorbing materials, such as ferrites, carbon-based composites (such as graphene, carbon nanotubes), and metal powder composites, usually need to be coated or cured at high temperatures. This high-temperature treatment process is to ensure that the materials form a stable microstructure, so as to obtain ideal electromagnetic and mechanical properties. For example, ferrite materials usually need to be sintered at temperatures above 800 °C to optimize their magnetic permeability and impedance matching; carbon-based composites require high-temperature annealing or heat treatment to improve their conductivity and interfacial bonding strength.

[0004] However, this high-temperature treatment process not only significantly increases production costs and energy consumption, but also limits the application of materials in temperature-sensitive substrates (such as polymers, plastics, flexible electronic devices) or special environments. In addition, high-temperature treatment may cause substrate deformation, oxidation or performance degradation, further limiting the scope of application of traditional electromagnetic wave absorbing materials. Therefore, developing a new material that can be directly coated at room temperature and has excellent electromagnetic wave absorption performance has become an important research direction. Such a material can not only reduce production costs and process complexity, but also expand the application potential of electromagnetic wave absorbing materials in emerging fields such as flexible electronics, wearable devices, and intelligent coatings. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of a wave-absorbing agent that can be coated at room temperature to solve the limitations of existing wave-absorbing materials in multiple application scenarios.

[0006] To achieve the above purpose, the present invention provides the following solution: A preparation method of a wave-absorbing agent that can be coated at room temperature is as follows: Step 1: Mix graphene and carbon nanotubes, stir evenly, add them into a crushing device, stir and crush, then add a mixture of a first portion of sodium silicate solution and aluminum dihydrogen phosphate solution, stir and crush, and then shear and pulverize into a primary small particle mixture. Then add kaolin, a mixture of a second portion of sodium silicate solution and aluminum dihydrogen phosphate solution to the primary small particles, disperse, stir and crush to obtain a small particle mixture, and then dry it to obtain a ceramic glass-carbon-based material; In Step 1, the particle size of the graphene is 1 - 5 μm; The diameter of the carbon nanotubes is 3 - 15 nm and the tube length is 15 - 30 μm; In the mixture of the first portion of sodium silicate solution and aluminum dihydrogen phosphate solution and the mixture of the second portion of sodium silicate solution and aluminum dihydrogen phosphate solution, the mass fraction of the sodium silicate solution is 35 - 37% and the mass fraction of the aluminum dihydrogen phosphate solution is 48 - 52%; In the mixture of the first portion of sodium silicate solution and aluminum dihydrogen phosphate solution and the mixture of the second portion of sodium silicate solution and aluminum dihydrogen phosphate solution, the mass ratio of the sodium silicate solution to the aluminum dihydrogen phosphate solution is 5:1.8 - 2.2; The particle size of the kaolin is 1000 - 1500 mesh; The particle sizes of the primary small particle mixture and the small particle mixture are both 100 - 400 μm; The mass ratio of graphene to carbon nanotubes is 10:2.8 - 3.2; The mass ratio of graphene, the mixture of the first portion of sodium silicate solution and aluminum dihydrogen phosphate solution, and the mixture of the second portion of sodium silicate solution and aluminum dihydrogen phosphate solution is 10:38 - 42:38 - 42; The mass fraction of kaolin in the ceramic glass-carbon-based material is 65 - 75%; The drying temperature is 60 - 80 °C and the time is 1.5 - 3 h; Step 2: Perform heat treatment on the ceramic glass-carbon-based material in a protective atmosphere, and then perform air atmosphere treatment to obtain a ceramic glass system-coated carbonaceous composite absorbing material; In Step 2, the protective atmosphere in the protective atmosphere heat treatment is argon, the temperature is 1100 - 1300 °C, and the time is 2 - 2.5 h; The temperature in the air atmosphere treatment is 700 - 800 °C and the time is 2 - 2.5 h; Step 3: Mix magnesium silicate, sodium silicate solution, silicon dioxide, and magnesium oxide evenly to obtain a composite binder; In Step 3, the mass ratio of magnesium silicate, sodium silicate solution, silicon dioxide, and magnesium oxide is 6:2 - 4:0.8 - 1.2:0.8 - 1.2; The concentration of sodium silicate in the sodium silicate solution is 33 - 35%; Step 4: Stir the ceramic glass system-coated carbonaceous composite microwave absorbing material and the composite binder evenly to obtain a microwave absorbing agent that can be coated at room temperature; In Step 4, the mass ratio of the ceramic glass system-coated carbonaceous composite microwave absorbing material to the composite binder is 8-12:1.

[0007] The present invention discloses the following technical effects: (1) The microwave absorbing agent that can be coated at room temperature prepared by the present invention is composed of a carbonaceous composite microwave absorbing material coated with a ceramic glass system and a composite binder with a specific composition. It combines the high-temperature resistance and oxidation resistance of the ceramic glass and the excellent microwave absorbing performance of the carbonaceous material, realizing stable microwave absorption in a high-temperature environment. At the same time, the composite binder is used to evenly disperse the powder, and the obtained microwave absorbing agent can be applied in various environments and has a wide application range; (2) The preparation method of the microwave absorbing agent that can be coated at room temperature of the present invention adopts a combination of shear granulation, vacuum drying and heat treatment during the preparation process, and successfully prepares a powder material with stable structure, low cost and environmental friendliness. At the same time, the composite binder is composed of magnesium silicate, sodium silicate, silicon dioxide and magnesium oxide, and has good high-temperature resistance, ensuring the high-temperature stability of the material and the close combination between components. The present invention further optimizes the microwave absorbing performance of the composite material at high temperature, making it not only have excellent high-temperature resistance, but also adapt to the application requirements of different scenarios. Therefore, this microwave absorbing agent has broad application prospects in fields such as aerospace, military equipment, and industrial manufacturing that require high-temperature environments, and its preparation process is simple and the cost is low, providing the possibility for its application in a wider range of fields; (3) When the thickness of the microwave absorbing agent that can be coated at room temperature prepared by the present invention is 2.0-3.0 mm, the reflection loss RL value is -24.70 dB to -21.14 dB, and the effective microwave absorbing bandwidth is 2.69-3.22 GHz; (4) The preparation method of the microwave absorbing agent that can be coated at room temperature of the present invention uses a high-temperature resistant composite binder. The composite binder contains magnesium silicate, sodium silicate, silicon dioxide and magnesium oxide, and is evenly mixed with the ceramic glass system-coated carbon-based composite microwave absorbing material. The ceramic glass system acts as a shell structure, which can isolate the contact between the internal carbonaceous material and oxygen, making the powder have good high-temperature resistance and oxidation resistance. The composite binder can promote the uniform dispersion of the ceramic glass system-coated carbon-based composite microwave absorbing material, so that a stable microwave absorbing coating can be formed at room temperature. The composite binder has excellent adhesion performance and high-temperature resistance characteristics, and can form a uniform and stable microwave absorbing coating at room temperature. By adjusting the composition of the composite binder, the microwave absorbing performance of the coating can be effectively improved and its stability in a high-temperature environment can be enhanced; (5) The wave-absorbing agent prepared by the present invention that can be coated at room temperature can not only effectively absorb and attenuate electromagnetic waves, reducing the electromagnetic radiation signal of the aircraft, but also has excellent stability and durability, ensuring that the coating maintains its performance in complex environments for a long time. The introduction of the composite binder enables the entire coating system to have good tolerance under high-temperature conditions, meeting the strict requirements for materials in the aerospace field. The application of this technology can not only effectively reduce the electromagnetic radiation signal of the aircraft, improve its stealth ability, but also enhance its survival ability in complex battlefield environments. The research and application of this technology have important theoretical significance and practical application value, providing a solid material foundation for the development of modern stealth technology and offering new ideas and solutions for the development of modern stealth technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0009] Figure 1 SEM photograph of the ceramic glass system-coated carbonaceous composite wave-absorbing material prepared in the second step of Example 1; Figure 2 Photograph of the wave-absorbing agent prepared in Example 1 after being coated on an 180mm×180mm test board; Figure 3 Schematic diagram of the wave-absorbing performance of the wave-absorbing agent prepared in Example 1 measured by the bow method in the frequency range of 2 - 18 GHz after coating. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0011] 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. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0012] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0013] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0014] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0015] The raw materials used in the examples and comparative examples of the present invention can all be purchased from the market, and the instruments and equipment used are all commonly used instruments and equipment in the art.

[0016] The following examples are used to further illustrate the technical solution of the present invention.

[0017] Example 1 A method for preparing a wave absorbing agent that can be coated at room temperature is as follows: 1. 10 parts by mass of graphene with a particle size of 1-5 μm and 3 parts by mass of carbon nanotubes with a diameter of 3-15 nm and a tube length of 15-30 μm are mixed, stirred evenly, placed in a crusher, and 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 are added while stirring, and stirred and crushed to obtain large block particles, and then sheared and crushed to a particle size of 100 μm, followed by adding kaolin with a particle size of 1250 mesh and 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 for dispersion, and stirred and crushed again to a particle size of 100 μm, and dried at a temperature of 60° C. for 2 h to obtain a ceramic glass-carbon-based material; Kaolin accounts for 70% by mass of the ceramic glass-carbon-based material; The kaolin is used as the ceramic phase, and the sodium silicate and aluminum dihydrogen phosphate are used as the glass phase. Through a reasonable proportion of the two, the ceramic glass system can have good performance.

[0018] 2. The ceramic glass-carbon-based material is heat-treated in a protective atmosphere. The atmosphere used is argon, and it is held at 1200 °C for 2 h; subsequently, it is treated in an air atmosphere and held at 700 °C for 2 h to obtain a ceramic glass system-coated carbonaceous composite microwave absorbing material; The functions of the protective atmosphere heat treatment and the air atmosphere treatment are to solidify the entire ceramic glass system.

[0019] The prepared ceramic glass system-coated carbonaceous composite microwave absorbing material is analyzed by scanning electron microscopy, and the obtained scanning electron micrograph is shown in Figure 1 , from Figure 1 it can be seen that in the ceramic glass system-coated carbonaceous composite microwave absorbing material, the outer layer is the ceramic glass system, the inner layer is the carbonaceous material, and the ceramic glass system coats the carbonaceous material.

[0020] 3. Magnesium silicate, sodium silicate solution, silicon dioxide, and magnesium oxide are mixed evenly according to a mass ratio of 6:3:1:1 to prepare a composite binder; The concentration of sodium silicate in the sodium silicate solution is 34%; In the composite binder, the main binder is the sodium silicate solution.

[0021] 4. The ceramic glass system-coated carbonaceous composite microwave absorbing material and the composite binder are stirred evenly according to a mass ratio of 10:1 to obtain a microwave absorbing agent that can be coated at room temperature.

[0022] The microwave absorbing agent prepared in this example is evenly coated on a test plate of 180 mm × 180 mm. The photograph of the coated microwave absorbing agent is shown in Figure 2 as shown; then, using the bow-tie method, the microwave absorption performance of the coated microwave absorbing agent in the frequency range of 2 - 18 GHz is tested, and the obtained microwave absorption performance schematic diagram is shown in Figure 3 as shown; from Figure 3 it can be seen that the microwave absorbing agent prepared in this example has the best microwave absorption in the X band. The specific reflection loss RL value is -24.70 dB (10.13 GHz), the effective absorption bandwidth is 3.22 GHz, and the thickness is 2.5 mm.

[0023] Example 2 A preparation method of a microwave absorbing agent that can be coated at room temperature is as follows: 1. Mix 10 parts by mass of graphene with a particle size of 1-5 μm and 3 parts by mass of carbon nanotubes with a diameter of 3-15 nm and a tube length of 15-30 μm, stir evenly, place in a crusher, add 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 while stirring, and stir and crush to obtain large block particles. The large block particles are sheared and crushed to a particle size of 100 μm, and then kaolin with a particle size of 1250 mesh and 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 are added for dispersion, and then stirred and crushed again to a particle size of 100 μm, and dried at a temperature of 60°C for 2 hours to obtain a ceramic glass-carbon-based material; The mass fraction of kaolin in the ceramic glass-carbon-based material is 70%.

[0024] 2. The ceramic glass-carbon-based material is subjected to a protective atmosphere heat treatment using argon gas and kept at 1200°C for 2 hours; it is then treated in an air atmosphere and kept at 700°C for 2 hours to obtain a ceramic glass system-coated carbon composite absorbing material.

[0025] 3. Mix magnesium silicate, sodium silicate solution, silicon dioxide and magnesium oxide in a mass ratio of 6:2:1:1 to prepare a composite binder; The concentration of sodium silicate in the sodium silicate solution is 34%.

[0026] 4. The carbon composite absorbing material powder coated with the ceramic glass system and the composite binder are uniformly mixed in a mass ratio of 10:1 to obtain an absorbing agent that can be coated at room temperature.

[0027] The absorber was evenly coated on a test plate of 180 mm×180 mm, and the best microwave absorption in the X-band was measured using the bow method. The specific reflection loss RL value was -22.86 dB (10.75 GHz), the effective absorbing bandwidth was 2.97 GHz, and the thickness was 2.0 mm.

[0028] Example 3 A method for preparing a wave absorbing agent that can be coated at room temperature is as follows: 1. Mix 10 parts by mass of graphene with a particle size of 1-5 μm and 3 parts by mass of carbon nanotubes with a diameter of 3-15 nm and a tube length of 15-30 μm, stir evenly, place in a crusher, add 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 while stirring, and stir and crush to obtain large block particles. The large block particles are sheared and crushed to a particle size of 100 μm, and then kaolin with a particle size of 1250 mesh and 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 are added for dispersion, and then stirred and crushed again to a particle size of 100 um, and dried at a temperature of 60 ° C for 2 hours to obtain a ceramic glass-carbon-based material; The mass fraction of kaolin in the ceramic glass-carbon-based material is 70%.

[0029] 2. The ceramic glass-carbon-based material is subjected to a protective atmosphere heat treatment using argon gas and kept at 1200°C for 2 hours; it is then treated in an air atmosphere and kept at 700°C for 2 hours to obtain a ceramic glass system-coated carbon composite absorbing material.

[0030] 3. Mix magnesium silicate, sodium silicate solution, silicon dioxide and magnesium oxide in a mass ratio of 6:4:1:1 to prepare a composite binder; The concentration of sodium silicate in the sodium silicate solution is 34%.

[0031] 4. The carbon composite absorbing material powder coated with the ceramic glass system and the composite binder are uniformly mixed in a mass ratio of 10:1 to obtain an absorbing agent that can be coated at room temperature.

[0032] The absorbent was evenly coated on a test plate of 180 mm×180 mm, and the best microwave absorption in the X-band was measured using the bow method. The specific reflection loss RL value was -21.14 dB (10.23 GHz), the effective absorbing bandwidth was 2.86 GHz, and the thickness was 3.0 mm.

[0033] Experimental Example 4 A method for preparing a wave absorbing agent that can be coated at room temperature is as follows: 1. Mix 10 parts by mass of graphene with a particle size of 1-5 μm and 3 parts by mass of carbon nanotubes with a diameter of 3-15 nm and a tube length of 15-30 μm, stir evenly, place in a crusher, add 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 while stirring, and stir and crush to obtain large block particles. The large block particles are sheared and crushed to a particle size of 100 μm, and then kaolin with a particle size of 1250 mesh and 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 are added for dispersion, and stirred and crushed again to a particle size of 100 μm, and dried at a temperature of 60°C for 2 hours to obtain a ceramic glass-carbon-based material; The mass fraction of kaolin in the ceramic glass-carbon-based material is 70%.

[0034] 2. The ceramic glass-carbon-based material is subjected to a protective atmosphere heat treatment using argon gas and kept at 1200°C for 2 hours; it is then treated in an air atmosphere and kept at 700°C for 2 hours to obtain a ceramic glass system-coated carbon composite absorbing material.

[0035] 3. Mix magnesium silicate, sodium silicate solution, silicon dioxide and magnesium oxide in a mass ratio of 6:3:1:1 to prepare a composite binder; The concentration of sodium silicate in the sodium silicate solution is 34%.

[0036] 4. The carbon composite absorbing material powder coated with the ceramic glass system and the composite binder are uniformly mixed in a mass ratio of 8:1 to obtain an absorbing agent that can be coated at room temperature.

[0037] The absorbent was evenly coated on a test plate of 180 mm×180 mm, and the best microwave absorption in the X-band was measured using the bow method. The specific reflection loss RL value was -21.31 dB (9.77 GHz), the effective absorbing bandwidth was 2.69 GHz, and the thickness was 2.0 mm.

[0038] Experimental Example 5 A method for preparing a wave absorbing agent that can be coated at room temperature is as follows: 1. Mix 10 parts by mass of graphene with a particle size of 1-5 μm and 3 parts by mass of carbon nanotubes with a diameter of 3-15 nm and a tube length of 15-30 μm, stir evenly, place in a crusher, add 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 while stirring, and stir and crush to obtain large block particles. The large block particles are sheared and crushed to a particle size of 100 μm, and then kaolin with a particle size of 1250 mesh and 40 parts by mass of a mixture of a 36% sodium silicate solution and a 50% aluminum dihydrogen phosphate solution with a mass ratio of 5:2 are added for dispersion, and then stirred and crushed again to a particle size of 100 μm, and dried at a temperature of 60°C for 2 hours to obtain a ceramic glass-carbon-based material; The mass fraction of kaolin in the ceramic glass-carbon-based material is 70%.

[0039] 2. The ceramic glass-carbon-based material is subjected to a protective atmosphere heat treatment using argon gas and kept at 1200°C for 2 hours; it is then subjected to an air atmosphere treatment and kept at 700°C for 2 hours to solidify the system and obtain a ceramic glass system-coated carbonaceous composite absorbing material.

[0040] 3. Mix magnesium silicate, sodium silicate solution, silicon dioxide and magnesium oxide in a mass ratio of 6:3:1:1 to prepare a composite binder; The concentration of sodium silicate in the sodium silicate solution is 34%.

[0041] 4. The carbon composite absorbing material powder coated with the ceramic glass system is evenly mixed with the composite binder in a mass ratio of 12:1 to obtain an absorbing agent that can be coated at room temperature.

[0042] The absorbent was evenly coated on a test plate of 180 mm × 180 mm, and the best microwave absorption in the X-band was measured using the bow method. The specific reflection loss RL value was -23.47 dB (10.31 GHz), the effective absorbing bandwidth was 3.12 GHz, and the thickness was 2.5 mm.

[0043] Comparative Example 1 The same as Example 1, except that the mass ratio of magnesium silicate, sodium silicate, silicon dioxide and magnesium oxide in the preparation of the composite binder in step 3 is changed to 6:6:1:1.

[0044] The absorbent that can be coated at room temperature with this ratio configuration is measured to have the best microwave absorption in the X-band, with a specific reflection loss RL value of -15.68dB (9.42GHz), an effective absorbing bandwidth of 1.43GHz, and a thickness of 2.5mm.

[0045] Comparative Example 2 Same as Example 1, except that in the preparation of the composite binder in Step 3, the mass ratio of magnesium silicate, sodium silicate solution, silicon dioxide, and magnesium oxide is changed to 6:1:1:1; The concentration of sodium silicate in the sodium silicate solution is 34%.

[0046] Measure the microwave absorber that can be coated at room temperature configured in this ratio. There is an optimal microwave absorption in the X-band. The specific reflection loss RL value is -13.69 dB (9.76 GHz), the effective absorption bandwidth is 0.97 GHz, and the thickness is 2.0 mm.

[0047] Comparative Example 3 Same as Example 1, except that in Step 4, the mass ratio of the ceramic glass system-coated carbonaceous composite absorber to the composite binder is changed to 5:1.

[0048] Measure the microwave absorber that can be coated at room temperature configured in this ratio. There is an optimal microwave absorption in the X-band. The specific reflection loss RL value is -12.56 dB (9.87 GHz), the effective absorption bandwidth is 0.63 GHz, and the thickness is 3.0 mm.

[0049] Comparative Example 4 Same as Example 1, except that in Step 4, the mass ratio of the ceramic glass system-coated carbonaceous composite absorber to the composite binder is changed to 15:1.

[0050] Measure the microwave absorber that can be coated at room temperature configured in this ratio. There is an optimal microwave absorption in the X-band. The specific reflection loss RL value is -17.32 dB (10.57 GHz), the effective absorption bandwidth is 1.80 GHz, and the thickness is 2.0 mm.

[0051] It can be seen from the results of the examples and comparative examples that the present invention realizes the ability to be coated at room temperature and improves the microwave absorption performance by using a composite binder, controlling the dosage of the composite components in the composite binder, and controlling the mass ratio of the ceramic glass system-coated carbonaceous composite absorber to the composite binder.

[0052] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of a microwave absorbing agent that can be coated at room temperature, characterized in that, The preparation method is as follows: Step 1: Mix graphene and carbon nanotubes, stir evenly, add them into a crushing device, stir and crush, then add a mixture of the first portion of sodium silicate solution and aluminum dihydrogen phosphate solution, stir and crush, and then shear and pulverize into a primary small particle mixture. Then, add kaolin, and a mixture of the second portion of sodium silicate solution and aluminum dihydrogen phosphate solution to the primary small particles, disperse, stir and crush to obtain a small particle mixture, and then dry it to obtain a ceramic glass-carbon based material; Step 2: Heat-treat the ceramic glass-carbon based material in a protective atmosphere, and then perform air atmosphere treatment to obtain a ceramic glass system-coated carbonaceous composite absorbing material; Step 3: Mix magnesium silicate, sodium silicate solution, silicon dioxide, and magnesium oxide evenly to obtain a composite binder; Step 4: Stir the ceramic glass system-coated carbonaceous composite absorbing material and the composite binder evenly to obtain an absorbing agent that can be coated at room temperature.

2. The preparation method of the microwave absorbing agent capable of being coated at room temperature according to claim 1, characterized in that In Step 1, the particle size of the graphene is 1 - 5 μm; The diameter of the carbon nanotubes is 3 - 15 nm, and the tube length is 15 - 30 μm.

3. The preparation method of the microwave absorbing agent capable of being coated at room temperature according to claim 1, wherein In Step 1, the mass fraction of the sodium silicate solution in both the mixture of the first portion of sodium silicate solution and aluminum dihydrogen phosphate solution and the mixture of the second portion of sodium silicate solution and aluminum dihydrogen phosphate solution is 35 - 37%, and the mass fraction of the aluminum dihydrogen phosphate solution is 48 - 52%; The particle size of the kaolin is 1000 - 1500 mesh; The particle sizes of both the primary small particle mixture and the small particle mixture are 100 - 400 μm; The drying temperature is 60 - 80 °C, and the time is 1.5 - 3 h.

4. The preparation method of the microwave absorbing agent capable of being coated at room temperature according to claim 1, characterized in that, In Step 1, the mass ratio of the sodium silicate solution to the aluminum dihydrogen phosphate solution in both the mixture of the first portion of sodium silicate solution and aluminum dihydrogen phosphate solution and the mixture of the second portion of sodium silicate solution and aluminum dihydrogen phosphate solution is 5:1.8 - 2.2; The mass ratio of graphene to carbon nanotubes is 10:2.8 - 3.2; The mass ratio of graphene, the mixture of the first portion of sodium silicate solution and aluminum dihydrogen phosphate solution, and the mixture of the second portion of sodium silicate solution and aluminum dihydrogen phosphate solution is 10:38 - 42:38 - 42; The mass fraction of kaolin in the ceramic glass-carbon based material is 65 - 75%.

5. The preparation method of the microwave absorbing agent capable of being coated at room temperature according to claim 1, characterized in that, In Step 2, the protective atmosphere for the heat treatment in the protective atmosphere is argon, the temperature is 1100 - 1300 °C, and the time is 2 - 2.5 h; The temperature for the air atmosphere treatment is 700 - 800 °C, and the time is 2 - 2.5 h.

6. The preparation method of the microwave absorbing agent capable of being coated at room temperature according to claim 1, characterized in that, In Step 3, the mass ratio of magnesium silicate, sodium silicate solution, silicon dioxide, and magnesium oxide is 6:2 - 4:0.8 - 1.2:0.8 - 1.

2.

7. The preparation method of the microwave absorbing agent capable of being coated at room temperature according to claim 1, characterized in that, In Step 3, the concentration of sodium silicate in the sodium silicate solution is 33 - 35%.

8. The preparation method of the microwave absorbing agent capable of being coated at room temperature according to claim 1, characterized in that, In Step 4, the mass ratio of the ceramic glass system-coated carbonaceous composite absorbing material to the composite binder is 8 - 12:1.

Images