Carbon-titanium-based wave-absorbing phase-change composite material and preparation method thereof

Abstract

The preparation method comprises the following steps: mixing titanium powder or TiO2 and carbon powder in a molar ratio of (0.8-2.0): 1 to obtain a mixture, mixing the mixture with V2O5 powder, reacting the mixture in a molten salt medium, calcining the reactant in a hydrogen atmosphere for 1-5 hours, cleaning and drying the calcined product, and drying to obtain the carbon-titanium-based wave-absorbing phase-change composite material. Grinding with an organic mixed reagent and a surfactant to form carbon-titanium-based wave-absorbing phase-change material slurry; and compounding the carbon-titanium-based wave-absorbing phase-change material slurry with a base material to obtain the carbon-titanium-based wave-absorbing phase-change composite material. The composite material has unique wave-absorbing and phase-change performance, electromagnetic parameters of composite particles can be effectively adjusted to realize impedance matching, and meanwhile, the composite structure has dielectric loss, conductive loss and multiple interface polarization loss mechanisms, so that the composite material has excellent wave-absorbing performance; meanwhile, the composite particles are endowed with a phase change heat absorption cooling function, the impedance mismatch phenomenon does not exist, and the interface polarization effect is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic protection, and particularly relates to a carbon-titanium-based wave-absorbing phase change composite material and a preparation method thereof. Background Art

[0002] With the rapid development of modern technology, the problem of electromagnetic radiation has gradually become the focus of public attention. In daily life, the widespread use of various electronic devices and electrical appliances inevitably generates electromagnetic radiation. These radiations can not only interfere with electronic devices but also potentially have negative impacts on human health. For example, in hospitals, electromagnetic radiation may interfere with the normal operation of electronic diagnostic equipment, thus affecting the accuracy of medical diagnosis. In addition, electromagnetic radiation may also affect the human nervous system, immune system, reproductive system, and cardiovascular system, etc., and even increase the risk of certain cancers. In the community environment, the electromagnetic energy leaked from electronic devices will spread into the indoor and outdoor air, and its intensity and frequency exceed the natural background value, which may cause discomfort to some residents and even have negative impacts on health and quality of life. Therefore, it has become an urgent task to develop high-performance electromagnetic wave absorbing materials to effectively solve the problems of electromagnetic interference and electromagnetic radiation pollution.

[0003] Electromagnetic wave absorbing materials can convert the electromagnetic wave energy entering the material into heat energy or other forms of energy, thereby reducing the harm of electromagnetic radiation to the environment and human health. However, the existing electromagnetic wave absorbing materials still have many deficiencies, such as poor impedance matching, narrow absorption bandwidth, single function, etc., and it is difficult to meet the actual application requirements. For example, traditional single-component carbon materials (such as carbon nanotubes, carbon black, etc.) cannot achieve ideal electromagnetic absorption performance due to lack of good impedance matching. An ideal electromagnetic wave absorbing material should have close complex permittivity and complex permeability to achieve efficient electromagnetic wave absorption.

[0004] Among many potential microwave absorbing materials, titanium carbide (TiC)-based composites are considered as a highly promising dielectric loss type of microwave absorbing material due to their excellent corrosion resistance, high melting point, high hardness and mechanical strength. However, the relative complex permittivity of pristine titanium carbide is low at room temperature, resulting in unsatisfactory dielectric loss and electromagnetic absorption performance. With the development of nanotechnology, the electromagnetic properties of carbides can be adjusted by means of size control, phase transformation, morphology design, doping, etc. Theoretically, strong leakage current is beneficial to efficient electromagnetic absorption, but the performance of electromagnetic wave absorbing materials does not only depend on the strength of leakage current. If the medium does not have good impedance matching, electromagnetic waves will be reflected at the transmission interface. Therefore, most single-component carbon materials (such as carbon nanotubes, carbon black, carbon fibers and graphite) cannot produce ideal electromagnetic absorption performance. The most ideal situation is that the electromagnetic wave absorbing material can have very close complex permittivity and complex permeability. Therefore, it is of great significance to develop a high-performance electromagnetic wave absorbing material with high absorption intensity, wide absorption bandwidth and diverse functions. Summary of the Invention

[0005] In order to overcome the defects existing in the above-mentioned prior art, the purpose of the present invention is to provide a carbon-titanium-based microwave absorbing phase change composite material with high absorption intensity, wide absorption bandwidth and functionality, and a preparation method thereof. By optimizing its structure and performance, the deficiencies of existing materials are solved. The novel composite material provided by the present invention has the characteristics of high absorption intensity, wide absorption bandwidth and multifunctionality, can effectively improve the electromagnetic wave absorption effect, and at the same time provides an innovative solution for solving the problems of electromagnetic interference and electromagnetic radiation pollution. The research and development of this material not only has important scientific significance, but also will show broad application prospects in the fields of electronic devices, military equipment, medical instruments, etc.

[0006] To achieve the above-mentioned invention purpose, the present invention provides a preparation method of a carbon-titanium-based microwave absorbing phase change composite material. The carbon-titanium-based microwave absorbing phase change composite material is composed of a substrate and a carbon-titanium-based microwave absorbing phase change material. When the substrate is foam, the carbon-titanium-based microwave absorbing phase change material is directly loaded on the foam by an immersion method. When the substrate is rubber, the carbon-titanium-based microwave absorbing phase change material is added during the rubber molding process. When preparing a microwave absorbing film, the carbon-titanium-based microwave absorbing phase change material is mixed evenly in a film-forming agent. Due to different application scenarios, the substrates required for the carbon-titanium-based microwave absorbing phase change material are also different. For example, if the substrate is foam, because of its many voids, this kind of microwave absorbing phase change composite material can be directly loaded on the foam by immersion. If the substrate is a product with few voids such as rubber, it needs to be added during the rubber molding process.

[0007] The preparation method of the carbon-titanium-based microwave absorbing phase change composite material includes the following steps:

[0008] ①Mix titanium powder or titanium dioxide powder and carbon powder evenly in a molar ratio of 0.8 - 2.0:1 to obtain mixture A; then mix mixture A with vanadium pentoxide powder evenly in a mass ratio of 5 - 15:1 to obtain mixture B.

[0009] ②React mixture B with a molten salt medium, where the mass of the molten salt medium is 8 - 20 times that of mixture B, to obtain reactant C.

[0010] ③Calcine reactant C in a hydrogen atmosphere for 1 - 5 h at a calcination temperature of 800 °C - 1100 °C; then wash the calcined product in water at 70 °C - 100 °C and vacuum dry it at 30 °C - 50 °C to obtain substance D.

[0011] ④Mix substance D with an organic mixed reagent and grind it to control the particle size to 30 - 150 nm to form slurry E; then add a surfactant with a mass fraction of 5% - 10% and mix for 10 - 15 min to obtain a carbon-titanium-based wave-absorbing phase change material slurry.

[0012] ⑤Compound the carbon-titanium-based wave-absorbing phase change material slurry with a substrate to obtain a carbon-titanium-based wave-absorbing phase change composite material.

[0013] In the above technical solution, further, the Ti mass content of the titanium powder in step ① is above 95%, and the particle size is 20 nm - 100 μm; the TiO₂ mass content of the titanium dioxide powder is above 95%, and the particle size is 20 nm - 10 μm; the C mass content of the carbon powder is above 95%, and the particle size is 10 nm - 10 μm; the V₂O₅ mass content of the vanadium pentoxide powder is above 99%, and the particle size is 0.5 - 10 μm.

[0014] Further, the molten salt medium in step ② is a mixture of chlorides, which is composed of one or more of sodium chloride, potassium chloride, calcium chloride, and magnesium chloride; when two chlorides are mixed, the mixing mass ratio is (1 - 3):1; when three chlorides are mixed, the mixing mass ratio is (1 - 3):(1 - 2):1; the mixing ratio of various chlorides plays a key role in controlling the eutectic point of the molten salt.

[0015] Further, the main component of substance D in step ③ is Ti x C y and VO₂.

[0016] Further, the mass ratio of each component of the organic mixed reagent in step ④ is ethyl acetate:dimethylformamide (DMF) or N-methylpyrrolidone (NMP):xylene (or toluene or acetone):terpineol (or polyethylene glycol 400 / 1000 / 2000):dispersant BYK (multiple models are available) = 9 - 12:3 - 4:6 - 8:1.

[0017] Furthermore, the surfactant described in step ④ is at least one of ethyl cellulose, polyvinylpyrrolidone, cetyltrimethylammonium chloride, and cetylpyridine.

[0018] Furthermore, when the carbon-titanium-based wave-absorbing phase change composite material prepared in step ⑤ is a wave-absorbing foam material, the carbon-titanium-based wave-absorbing phase change material slurry obtained in step ④ is added to a gelling agent at a mass concentration of 2% - 8% to form a solution, and then the foam is soaked in the solution for 30 - 60 minutes, taken out and dried to obtain a wave-absorbing phase change foam.

[0019] Furthermore, when the carbon-titanium-based wave-absorbing phase change composite material prepared in step ⑤ is a wave-absorbing phase change film, the carbon-titanium-based wave-absorbing phase change material slurry obtained in step ④ is added to a film-forming agent at a mass concentration of 5% - 20%, and a wave-absorbing phase change film is formed by magnetron sputtering or a coater.

[0020] Furthermore, when the carbon-titanium-based wave-absorbing phase change composite material prepared in step ⑤ is a wave-absorbing phase change rubber, the carbon-titanium-based wave-absorbing phase change material slurry obtained in step ④ is dispersed in a rubber molding agent at a mass concentration of 5% - 15%, and the rubber is cured to obtain a wave-absorbing phase change rubber.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] ① The carbon-titanium-based wave-absorbing phase change composite material obtained by this technical solution has unique wave-absorbing and phase change properties, can effectively adjust the electromagnetic parameters of the composite particles to achieve impedance matching, and at the same time, the composite structure has dielectric loss, conductive loss, and multiple interface polarization loss mechanisms, making the composite material have excellent wave-absorbing performance.

[0023] ② This composite material endows the composite particles with the function of phase change heat absorption and temperature reduction, can achieve good heat conduction and heat dissipation effects, and the contained vanadium dioxide has good dielectric and electrical properties, without impedance mismatch phenomenon, enhancing the interface polarization effect.

[0024] ③ This composite material is an in-situ generated composite material, and its performance is more compatible and has stronger firmness than the material directly constructed by simple mixing.

[0025] ④ The preparation method of the carbon-titanium-based wave-absorbing phase change composite material obtained by this technical solution is simple, has a wide range of application scenarios, does not limit the substrate, is green and environmentally friendly throughout the process, and is suitable for large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the carbon-titanium-based wave-absorbing phase change composite material of the present invention;

[0027] In the figure: 1 - carbon-titanium-based particle; 2 - vanadium dioxide phase change particle; 3 - substrate structure. Detailed implementation mode

[0028] The present invention will be further described below in conjunction with specific embodiments, but it is not limited to the present invention in any way. To avoid repetition, in the following embodiments, raw materials are commercially available products unless otherwise specified, and methods used are conventional methods unless otherwise specified.

[0029] A preparation method of a carbon-titanium-based wave-absorbing phase-change composite material, wherein the carbon-titanium-based wave-absorbing phase-change composite material is composed of a substrate and a carbon-titanium-based wave-absorbing phase-change material;

[0030] The preparation method of the carbon-titanium-based wave-absorbing phase-change composite material includes the following steps:

[0031] ① Mix titanium powder or titanium dioxide powder and carbon powder evenly at a molar ratio of 0.8-2.0:1 to obtain mixture A; then mix mixture A and vanadium pentoxide powder evenly at a mass ratio of 5-15:1 to obtain mixture B; the Ti mass content of the titanium powder is 98.5%, and the particle size is 6 μm; the TiO2 mass content of the titanium dioxide powder is 98.0%, and the particle size is 8 μm; the C mass content of the carbon powder is 97.6%, and the particle size is 200 nm; the V2O5 mass content of the vanadium pentoxide powder is 99.6%, and the particle size is 1.5 μm.

[0032] ② React mixture B with a molten salt medium, and the mass of the molten salt medium is 8-20 times the mass of mixture B to obtain reactant C;

[0033] ③ Calcinate reactant C in a hydrogen atmosphere for 1-5 h, and the calcination temperature is 800 °C-1100 °C; then wash the calcined product in water at 70 °C-100 °C and vacuum dry it at 30 °C-50 °C to obtain substance D;

[0034] ④ Mix and grind substance D with an organic mixed reagent, control the particle size to be 30-150 nm to form slurry E; then add a surfactant with a mass fraction of 5%-10% and mix for 10-15 min to obtain a carbon-titanium-based wave-absorbing phase-change material slurry;

[0035] ⑤ Composite the carbon-titanium-based wave-absorbing phase-change material slurry with the substrate to obtain a carbon-titanium-based wave-absorbing phase-change composite material.

[0036] For the parts not described in the following embodiments, they are the same as the description content of the above specific implementation mode.

[0037] Example 1

[0038] A preparation method of a carbon-titanium-based wave-absorbing phase-change composite material includes the following steps:

[0039] ①Mix titanium powder and carbon powder evenly in a molar ratio of 1:1 to obtain mixture A; then mix mixture A with vanadium pentoxide powder evenly in a mass ratio of 5:1 to obtain mixture B;

[0040] ②React mixture B with a molten salt medium, where the mass of the molten salt medium is 12 times that of mixture B, to obtain reactant C; the molten salt medium is composed of sodium chloride and potassium chloride mixed in a molar ratio of 1:1.

[0041] ③Calcine reactant C in a hydrogen atmosphere for 2 h at a calcination temperature of 950 °C; then wash the product obtained by calcination in water at 70 °C and vacuum dry it at 30 °C to obtain substance D; substance D is mainly a mixture of titanium carbide (Ti x C y ) and VO2, where the titanium carbide has wave-absorbing function and VO2 endows this material with the function of phase change endothermic cooling.

[0042] ④Mix and grind substance D with an organic mixed reagent in a sand mill, control the particle size to 50 nm, to form a uniform and stable slurry E; then add 5% by mass of the surfactant ethyl cellulose and mix for 10 min to obtain a carbon-titanium-based wave-absorbing phase change material slurry; the formula of the organic mixed reagent is ethyl acetate: dimethylformamide (DMF): toluene: polyethylene glycol 400: BYK = 9:3:6:1 (mass ratio).

[0043] ⑤Compound the carbon-titanium-based wave-absorbing phase change material slurry with a substrate: add the carbon-titanium-based wave-absorbing phase change material slurry obtained in step ④ into a curable gelling agent at a mass concentration of 6% and mix to form a solution, then soak the foam in the solution for 40 min, take it out and dry it to obtain a wave-absorbing phase change foam, which is the carbon-titanium-based wave-absorbing phase change composite material.

[0044] Perform relevant performance tests on the product prepared in Example 1. The phase change temperature of the mixture of titanium carbide (Ti x C y ) and VO2 in substance D is 35 °C (lower than the common phase change temperature of 68 °C of original vanadium dioxide). The wave-absorbing foam surface has good self-cleaning performance, and its contact angle and rolling angle reach 145.2° and 6.9° respectively, without affecting the performance of the foam itself, and still maintains an ultra-high absorption rate of 99.2% in the frequency range of 0.3 - 1.2 THz.

[0045] Example 2

[0046] A preparation method of a carbon-titanium-based wave-absorbing phase change composite material, comprising the following steps:

[0047] ① Mix titanium dioxide powder and carbon powder evenly in a molar ratio of 0.8:1 to obtain mixture A; then mix mixture A with vanadium pentoxide powder evenly in a mass ratio of 8:1 to obtain mixture B;

[0048] ② React mixture B with a molten salt medium, where the mass of the molten salt medium is 15 times the mass of mixture B, to obtain reactant C; the molten salt medium is composed of sodium chloride, potassium chloride, and calcium chloride mixed in a molar ratio of 1:1:1.

[0049] ③ Calcinate reactant C in a hydrogen atmosphere for 4 h at a calcination temperature of 900 °C; then wash the product obtained by calcination in water at 90 °C and vacuum dry it at 40 °C to obtain substance D; substance D is mainly a mixture of titanium carbide (Ti x C y ) and VO2, where the titanium carbide has wave-absorbing function and VO2 endows this material with the function of phase change endothermic cooling.

[0050] ④ Mix and grind substance D with an organic mixed reagent in a sand mill, control the particle size to 100 nm, to form a uniform and stable slurry E; then add 8% by mass of the surfactant polyvinylpyrrolidone and mix for 15 min to obtain a carbon-titanium-based wave-absorbing phase change material slurry; the formula of the organic mixed reagent is ethyl acetate:N-methylpyrrolidone (NMP):xylene:terpineol:BYK (multiple models are available)=12:4:8:1 (mass ratio).

[0051] ⑤ Compound the carbon-titanium-based wave-absorbing phase change material slurry with a substrate: add the carbon-titanium-based wave-absorbing phase change material slurry obtained in step ④ to a film-forming agent at a mass concentration of 10%, and use magnetron sputtering to form a uniform thin film, which is a wave-absorbing phase change thin film, thereby obtaining a carbon-titanium-based wave-absorbing phase change composite material.

[0052] Perform relevant performance tests on the product prepared in Example 2. The wave-absorbing thin film also has a phase change function at 45 °C, an infrared barrier rate of 67%, a UV barrier rate of 100%, can be used for intelligent temperature control wave-absorbing thin films, and still maintains an ultra-high absorption rate of 99.5% in the frequency range of 0.3 - 1.2 THz.

[0053] Example 3

[0054] A preparation method of a carbon-titanium-based wave-absorbing phase change composite material, comprising the following steps:

[0055] ① Mix titanium powder and carbon powder evenly in a molar ratio of 1.5:1 to obtain mixture A; then mix mixture A with vanadium pentoxide powder evenly in a mass ratio of 15:1 to obtain mixture B;

[0056] ② React mixture B with a molten salt medium, where the mass of the molten salt medium is 15 times the mass of mixture B, to obtain reactant C;

[0057] ③ Calcinate reactant C in a hydrogen atmosphere for 4 h at a calcination temperature of 800 °C; then wash the product obtained by calcination in water at 100 °C and vacuum dry it at 50 °C to obtain substance D; substance D is mainly a mixture of titanium carbide (Ti x C y ) and VO2, where the titanium carbide has wave-absorbing function and VO2 imparts the function of phase change endothermic cooling to this material.

[0058] ④ Mix and grind substance D with an organic mixed reagent in a sand mill, control the particle size to 80 nm to form a uniform and stable slurry E; then add 6% by mass of the surfactant cetylpyridine and mix for 12 min to obtain a carbon-titanium-based wave-absorbing phase change material slurry; among them, the formula of the organic mixed reagent is N,N-dimethylformamide (DMF): acetone: polyethylene glycol 2000: BYK = 12:4:8:1 (mass ratio).

[0059] ⑤ Compound the carbon-titanium-based wave-absorbing phase change material slurry with a substrate: Disperse the carbon-titanium-based wave-absorbing phase change material slurry obtained in step ④ in a rubber molding agent at a mass concentration of 10%, and make a rubber sheet through electrospinning technology. After the rubber is cured, a wave-absorbing phase change rubber is obtained, thereby obtaining a carbon-titanium-based wave-absorbing phase change composite material.

[0060] Perform relevant performance tests on the product prepared in Example 3, and still maintain an ultra-high absorption rate of 99.4% in the frequency range of 0.3 - 1.2 THz.

[0061] For any person skilled in the art, without departing from the scope of the technical solution of the present invention, many possible changes and modifications can be made to the technical solution of the present invention by using the technical content disclosed above, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A preparation method of a carbon-titanium-based wave-absorbing phase-change composite material, characterized in that The carbon-titanium-based microwave absorbing phase change composite material is composed of a substrate and a carbon-titanium-based microwave absorbing phase change material; The preparation method of the carbon-titanium-based microwave absorbing phase change composite material includes the following steps: ① Mix titanium powder or titanium dioxide powder and carbon powder evenly at a molar ratio of 0.8-2.0:1 to obtain mixture A; then mix mixture A and vanadium pentoxide powder evenly at a mass ratio of 5-15:1 to obtain mixture B; ② React mixture B with a molten salt medium, and the mass of the molten salt medium is 8-20 times the mass of mixture B to obtain reactant C; ③ Calcinate reactant C in a hydrogen atmosphere for 1-5 h, and the calcination temperature is 800 °C - 1100 °C; then wash the calcined product in water at 70 °C - 100 °C and vacuum dry it at 30 °C - 50 °C to obtain substance D; ④ Mix and grind substance D with an organic mixed reagent, control the particle size to be 30-150 nm to form slurry E; then add a surfactant with a mass fraction of 5%-10% and mix for 10-15 min to obtain a carbon-titanium-based microwave absorbing phase change material slurry; ⑤ Compound the carbon-titanium-based microwave absorbing phase change material slurry with the substrate to obtain a carbon-titanium-based microwave absorbing phase change composite material.

2. The preparation method according to claim 1, characterized in that, When the substrate is foam, directly load the carbon-titanium-based microwave absorbing phase change material on the foam by soaking; when the substrate is rubber, add the carbon-titanium-based microwave absorbing phase change material during the rubber molding process; when preparing a microwave absorbing film, mix the carbon-titanium-based microwave absorbing phase change material evenly in a film-forming agent.

3. The preparation method according to claim 1, wherein, In step ①, the Ti mass content of the titanium powder is more than 95%, and the particle size is 20 nm - 100 μm; the TiO2 mass content of the titanium dioxide powder is more than 95%, and the particle size is 20 nm - 10 μm; the C mass content of the carbon powder is more than 95%, and the particle size is 10 nm - 10 μm; the V2O5 mass content of the vanadium pentoxide powder is more than 99%, and the particle size is 0.5 - 10 μm.

4. The preparation method according to claim 1, characterized in that, In step ②, the molten salt medium is a mixture of chlorides, which is composed of one or more of sodium chloride, potassium chloride, calcium chloride, and magnesium chloride; when two chlorides are mixed, the mixing mass ratio is 1-3:1; when three chlorides are mixed, the mixing mass ratio is (1-3):(1-2):

1.

5. The preparation method according to claim 1, wherein The main component of the substance D described in step ③ is Ti x C y and VO2 6. The preparation method according to claim 1, characterized in that In step ④, the mass ratio of each component of the organic mixed reagent is ethyl acetate: dimethylformamide (DMF) or N-methylpyrrolidone (NMP): xylene, toluene or acetone: terpineol or polyethylene glycol: dispersant BYK = 9-12:3-4:6-8:

1.

7. The preparation method according to claim 1, characterized in that, The surfactant in step ④ is at least one of ethyl cellulose, polyvinylpyrrolidone, cetyltrimethylammonium chloride, and cetylpyridine.

8. The preparation method according to claim 1, characterized in that, When the carbon-titanium-based microwave absorbing phase change composite material prepared in step ⑤ is a microwave absorbing foam material, add the carbon-titanium-based microwave absorbing phase change material slurry obtained in step ④ to a gelling agent at a mass concentration of 2%-8% to form a solution, then soak the foam in the solution for 30-60 min, take it out and dry it to obtain a microwave absorbing phase change foam.

9. The preparation method according to claim 1, characterized in that, When the carbon-titanium-based microwave-absorbing phase change composite material prepared in step ⑤ is a microwave-absorbing phase change thin film, the carbon-titanium-based microwave-absorbing phase change material slurry obtained in step ④ is added to the film-forming agent at a mass concentration of 5% to 20%, and a microwave-absorbing phase change thin film is formed by magnetron sputtering or a coater.

10. The preparation method according to claim 1, characterized in that, When the carbon-titanium-based microwave-absorbing phase change composite material prepared in step ⑤ is a microwave-absorbing phase change rubber, the carbon-titanium-based microwave-absorbing phase change material slurry obtained in step ④ is dispersed in the rubber molding agent at a mass concentration of 5% to 15%, and the microwave-absorbing phase change rubber is obtained after the rubber is cured.

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