Preparation method of super-hydrophobic wave-absorbing material, super-hydrophobic wave-absorbing material prepared by the method and application thereof

Abstract

The application relates to a preparation method of super-hydrophobic wave-absorbing material, super-hydrophobic wave-absorbing material prepared by the method and application of the super-hydrophobic wave-absorbing material, realizes balance of magnetic loss and dielectric loss, plays a synergistic role of a magnetic material and hexagonal boron nitride, greatly improves wave-absorbing performance of the material, and realizes reduction of the density of the whole material; the material is more high-temperature-resistant, chemically stable, resistant to strong acid corrosion and the like, application scenarios of the material are effectively expanded; the operation is simple, the target product is high in purity, and large-batch synthesis can be realized.

Description

Technical Field

[0001] This invention relates to the field of materials, and in particular to a method for preparing a superhydrophobic microwave absorbing material, the superhydrophobic microwave absorbing material prepared by the method, and its applications. Background Technology

[0002] Electromagnetic radiation pollution is the fourth largest source of environmental pollution. It can affect human life and survival, as well as the operation of communication and electronic equipment, leading to information leaks. Therefore, developing materials that effectively shield and absorb electromagnetic waves is extremely urgent. Traditional magnetic absorbing materials, including magnetic metal nanoparticles such as iron, cobalt, and nickel nanoparticles, suffer from problems such as high density, poor corrosion resistance, and imbalance between dielectric and magnetic losses. Carbon materials, on the other hand, have become a candidate material for microwave absorbing materials due to their advantages such as large specific surface area, good stability, and low cost. Therefore, a large number of composite materials of carbon materials and magnetic metals have been studied. The combination of these two materials can overcome the shortcomings of traditional magnetic absorbing materials and improve their performance. However, most carbon materials are not resistant to high temperatures and have poor hydrophobicity, limiting their application scenarios.

[0003] Therefore, there is an urgent need for a method to prepare microwave absorbing materials that achieve a balance between magnetic loss and dielectric loss and have good superhydrophobicity. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing a microwave absorbing material that achieves a balance between magnetic loss and dielectric loss and has good superhydrophobicity.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for preparing a superhydrophobic microwave absorbing material, comprising the following steps:

[0007] S1. Weigh the raw materials according to the ratio of 20-35 mmol of cobalt source and 50-100 ml of deionized water for every 9 g of boron nitrogen source, and mix the boron nitrogen source, cobalt source and deionized water thoroughly to prepare the precursor solution.

[0008] S2. Evaporate the precursor solution at a temperature of 50-80 °C until it becomes viscous to obtain a pyrolytic precursor;

[0009] S3. The pyrolysis precursor is calcined in an ammonia atmosphere and then naturally cooled to obtain a black, fluffy powder;

[0010] S4. Wash the black, fluffy powder with ethanol and dry it to obtain the superhydrophobic microwave absorbing material.

[0011] Furthermore, the cobalt source is cobalt acetate tetrahydrate; the boron-nitrogen source is a mixture of boron trioxide and urea in a mass ratio of 1:2, or a mixture of boric acid and urea in a mass ratio of 1:2.

[0012] Furthermore, in step S3, the calcination temperature is 800-1300℃, the ammonia flow rate is 30-150ml / min, the heating rate is 1-10℃, and the calcination time is 30min-6h.

[0013] Preferably, in step s4, after washing the black, fluffy powder with ethanol, the solid is further subjected to a vacuum drying step of vacuum drying at 60-100°C for 12-24 hours.

[0014] The present invention also provides a superhydrophobic absorbing material prepared by the above method.

[0015] Furthermore, the material has a core-shell microstructure; the core of the core-shell microstructure is a cobalt nanoparticle, and the shell enclosing the cobalt nanoparticle is composed of hexagonal boron nitride; the cobalt nanoparticle has a particle size of 15-80 nm.

[0016] The present invention also provides an application of the above-mentioned superhydrophobic microwave absorbing material in the production of microwave absorbing coatings.

[0017] The present invention also provides an application of the above-mentioned superhydrophobic microwave absorbing material in the production of a superhydrophobic and microwave absorbing coating.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) Hexagonal boron nitride has a structure similar to graphite carbon. Nitrogen and boron atoms are covalently bonded to form hexagonal network layers that overlap to form crystals with similar crystal parameters. This invention combines hexagonal boron nitride with magnetic cobalt nanoparticles to obtain a core-shell structured superhydrophobic microwave absorbing material that meets the current development requirements of microwave absorbing materials, such as thin absorption thickness, light weight, and strong absorption intensity. In this composite microwave absorbing material, the interaction between the magnetic cobalt core and the shell hexagonal boron nitride can effectively control the agglomeration of magnetic cobalt and reduce some magnetic loss. By adjusting the synthesis conditions, a balance between magnetic loss and dielectric loss is achieved, giving full play to the synergistic effect of magnetic materials and hexagonal boron nitride, greatly improving the microwave absorption performance of the material, and reducing the overall density of the material.

[0020] (2) The layered structure of hexagonal boron nitride in the microscopic state (thickness less than 10 nm) has the advantages of high temperature resistance, chemical stability and strong acid corrosion resistance, which effectively expands the application scenarios of the material.

[0021] (3) The present invention uses a composite of hexagonal boron nitride and magnetic cobalt nanoparticles, which has better hydrophobic properties than the carbon material composites of the prior art.

[0022] (4) The present invention uses a simple synthesis method to obtain the pyrolysis precursor, which is simple to operate, has high purity of target product, and can realize large-scale synthesis. Attached Figure Description

[0023] Figure 1 The XRD patterns of the materials prepared in Examples 1, 2, and 3 of this invention are shown.

[0024] Figure 2 The TEM spectra of the materials prepared in Examples 1, 2, and 3 of this invention are shown.

[0025] Figure 3 shows the electromagnetic parameters of the materials made in Embodiments 1, 2, and 3 of the present invention: (a) real part of dielectric constant (ε′); (b) imaginary part of dielectric constant (ε″); (c) real part of magnetic permeability (μ′); (d) imaginary part of magnetic permeability (μ″); (e) dielectric loss tangent (tanδε); (f) magnetic loss tangent (tanδµ).

[0026] Figure 4 The diagram shows the wave absorption and reflection loss of the materials prepared in Embodiments 1, 2, and 3 of the present invention.

[0027] Figure 5 These are photographs showing the superhydrophobic properties of the materials prepared in Examples 1, 2, and 3 of this invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to specific embodiments. Example 1

[0029] This embodiment provides a method for preparing a core-shell structured hexagonal boron nitride-coated cobalt nanoparticle composite material: Boron trioxide and urea (total mass 9 g) in a mass ratio of 1:2 are simultaneously dissolved in 70 mL of deionized water and stirred thoroughly to obtain solution A; solution A is then rotary evaporated at 80 °C until it becomes viscous to obtain a pyrolysis precursor; the obtained pyrolysis precursor is then transferred to a corundum ceramic boat, placed in a tube furnace, and calcined for 5 h under an ammonia atmosphere at a temperature of 900 °C, an ammonia flow rate of 100 mL / min, and a heating rate controlled at 5 °C / min; after natural cooling, a black, fluffy powder is obtained. Finally, the obtained black powder is washed three times with ethanol and then dried under vacuum at 80 °C for 12 h to obtain the hexagonal boron nitride-coated cobalt nanoparticle composite material. XRD analysis revealed distinct characteristic peaks in hexagonal boron nitride at 2θ values ​​of 26.7º, 41.6º, and 50.0º, indicating successful synthesis of hexagonal boron nitride. Furthermore, the absence of characteristic diffraction peaks of metals (such as...) without the addition of a cobalt source was confirmed. Figure 1 As shown in Example 1). Example 2

[0030] This embodiment provides a method for preparing a core-shell structured hexagonal boron nitride-coated cobalt nanoparticle composite material: 8.5 mmol of cobalt acetate tetrahydrate and boron trioxide and urea (total mass 9 g) in a 1:2 mass ratio were simultaneously dissolved in 70 mL of deionized water and stirred thoroughly to obtain solution A. Solution A was then rotary evaporated at 80 °C until it reached a viscous state, yielding a pyrolysis precursor. The obtained pyrolysis precursor was then transferred to a corundum ceramic boat and placed in a tube furnace, where it was calcined for 5 h under an ammonia atmosphere at 900 °C, an ammonia flow rate of 100 mL / min, and a heating rate of 5 °C / min. Natural cooling yielded a black, fluffy powder. Finally, the black powder was washed three times with ethanol and then dried under vacuum at 80 °C for 12 h to obtain the hexagonal boron nitride-coated cobalt nanoparticle composite material. XRD analysis revealed distinct characteristic peaks in hexagonal boron nitride at 2θ values ​​of 26.7º, 41.6º, and 50.0º, indicating successful synthesis. Upon addition of cobalt, distinct diffraction characteristic peaks appeared at 2θ values ​​of 44.2º, 51.5º, and 75.8º, indicating the formation of cobalt (e.g., ...). Figure 1 As shown in Example 2). Simultaneously, TEM further confirmed the presence of metallic cobalt and hexagonal boron nitride, and it was clearly observable that the sample structure was a core-shell structure with hexagonal boron nitride as the shell and metallic cobalt (Co) as the core (as shown in Example 2). Figure 2 (As shown).

[0031] The superhydrophobic absorbing material prepared in this embodiment has a core-shell microstructure as described above; the core of the core-shell microstructure is a cobalt nanoparticle, and the shell enclosing the cobalt nanoparticle is composed of hexagonal boron nitride; the cobalt nanoparticle has a particle size of 15-80 nm. Example 3

[0032] This embodiment provides a method for preparing a core-shell structured hexagonal boron nitride-coated cobalt nanoparticle composite material: 16 mmol of cobalt acetate tetrahydrate and boron trioxide and urea (total mass 9 g) in a 1:2 mass ratio were simultaneously dissolved in 70 mL of deionized water and stirred thoroughly to obtain solution A. Solution A was then rotary evaporated at 80 °C until it reached a viscous state to obtain a pyrolysis precursor. The obtained pyrolysis precursor was then transferred to a corundum ceramic boat and placed in a tube furnace, where it was calcined for 5 h under an ammonia atmosphere at a temperature of 900 °C, an ammonia flow rate of 100 mL / min, and a heating rate of 5 °C / min. After natural cooling, a black, fluffy powder was obtained. Finally, the obtained black powder was washed three times with ethanol and then dried under vacuum at 80 °C for 12 h to obtain the hexagonal boron nitride-coated cobalt nanoparticle composite material. XRD analysis revealed distinct characteristic peaks of hexagonal boron nitride at 2θ values ​​of 26.7º, 41.6º, and 50.0º, indicating successful synthesis. With the addition of more cobalt, distinct diffraction characteristic peaks appeared at 2θ values ​​of 44.2º, 51.5º, and 75.8º, with stronger peak intensities than in Example 2, indicating the formation of cobalt (e.g., ...). Figure 1 (As shown in Example 3). Example 4

[0033] This embodiment provides an application of the superhydrophobic microwave absorbing material prepared by any of the methods in Examples 1-3 in coating preparation: the superhydrophobic microwave absorbing material is mixed with polyamide adhesive, photoinitiator, etc., to prepare a UV-curable coating, which is then applied to the surface of a pre-formed workpiece. Ultraviolet light is used to irradiate the coating until it is completely cured, resulting in a superhydrophobic microwave-absorbing coating. Alternatively, the material can be added to thermosetting coatings or latex paints to prepare a superhydrophobic and microwave-absorbing coating, which can then be further used to form a coating. Figure 5 As can be seen, the material forms clustered droplets on the glass slide with smooth, raised edges, rather than spreading out on the slide, indicating that the material has a certain degree of hydrophobicity. In optional embodiments, even if only a coating with microwave absorption properties is needed, the superhydrophobic microwave absorbing material prepared by any of the methods in Examples 1-3 can be used.

Claims

1. A method for preparing a superhydrophobic microwave absorbing material, wherein the superhydrophobic microwave absorbing material is a core-shell structured hexagonal boron nitride-coated cobalt nanoparticle composite material, characterized in that: The specific steps of this method are as follows: Take 16 mmol of cobalt acetate tetrahydrate and boron trioxide and urea in a mass ratio of 1:2, dissolve them in 70 mL of deionized water, and stir thoroughly to obtain solution A; Solution A was then rotary evaporated at 80 °C until it became viscous to obtain a pyrolysis precursor. The obtained pyrolysis precursor was transferred to a corundum ceramic boat and placed in a tube furnace. It was then calcined for 5 h under an ammonia atmosphere at a temperature of 900 °C, an ammonia flow rate of 100 mL / min, and a heating rate of 5 °C / min. After natural cooling, a black, fluffy powder was obtained. The black powder was washed three times with ethanol and then dried under vacuum at 80 °C for 12 h to obtain a hexagonal boron nitride-coated cobalt nanoparticle composite material.

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