Preparation method of multilayer spheroidal composite wave-absorbing material

Abstract

The invention discloses a preparation method of a multilayer sphere-like composite wave-absorbing material, and the preparation method comprises the following steps: (1) adding nickel nitrate hexahydrate, trimesic acid and polyvinylpyrrolidone into a solvent, and mixing to prepare a mixed solution; (2) transferring the mixed solution into a polytetrafluoroethylene lining reaction kettle for reaction to prepare a spherical Ni-MOF material; (3) the spherical Ni-MOF material and the Ti < 3 > C < 2 > T < X > powder are mixed, and Ni-MOF / Ti < 3 > C < 2 > T < X > mixed powder is prepared; and (4) the Ni-MOF / Ti3C2TX mixed powder and melamine are mixed, melamine mixed powder is prepared, the melamine mixed powder is transferred into a tubular furnace to be sintered, and a finished product is prepared. When the thickness of the prepared wave-absorbing composite material is 1.75 mm, RLmin is-65.1 dB, and the effective absorption frequency band is as high as 6.50 GHz.

Description

Technical Field

[0001] The present application belongs to the field of electromagnetic wave absorbing materials, and in particular to a method for preparing a multilayer spherical composite absorbing material. Background Art

[0003] Electromagnetic wave absorbing materials are mainly divided into two categories: metal electromagnetic wave absorbing materials and polymer electromagnetic wave absorbing materials. Metal electromagnetic wave absorbing materials, such as materials made of metals such as iron, nickel, and copper, have good electrical conductivity and magnetic permeability and can effectively absorb electromagnetic waves. Polymer electromagnetic wave absorbing materials are composite materials composed of polymer materials (such as polymers, rubber, etc.) and absorbing fillers (such as carbon black, iron oxide, etc.), and have good flexibility and plasticity.

[0004] The prior art CN112920773A is a hollow core-shell NiCo alloy @C ultra-thin absorber derived from a trimetallic organic framework and a preparation method thereof. Nickel nitrate hexahydrate, cobalt nitrate hexahydrate and zinc nitrate hexahydrate are used as metal salt precursors, trimesic acid is used as an organic ligand, N,N-dimethylformamide, ethanol and deionized water are used as a mixed solvent, and a hollow core-shell NiCo alloy @C nanocomposite material is prepared by a high-temperature pyrolysis method.

[0005] In the present application, the absorbing performance of the electromagnetic wave absorbing material can be further improved by adjusting the raw materials of the electromagnetic wave absorbing material. Summary of the invention

[0006] The present application provides a method for preparing a multi-layer spherical composite absorbing material to solve the above-mentioned problem.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A method for preparing a multilayer spherical composite absorbing material comprises the following steps:

[0009] (1) adding nickel nitrate, trimesic acid and polyvinyl pyrrolidone into a solvent and mixing to prepare a mixed solution;

[0010] (2) transferring the mixed solution to a polytetrafluoroethylene-lined reactor for reaction to obtain a spherical Ni-MOF material;

[0011] (3) Spherical Ni-MOF materials and Ti3C2T X Powder mixing to obtain Ni-MOF / Ti3C2T X Mixing powders;

[0012] (4) Ni-MOF / Ti3C2T X The mixed powder is mixed with melamine to obtain the melamine mixed powder, and the melamine mixed powder is transferred to a tubular furnace for sintering to obtain a finished product.

[0013] Furthermore, in step (1), the mass ratio of nickel nitrate, trimesic acid, polyvinyl pyrrolidone and solvent is 0.2-0.6:0.05-0.15:0.9-1.1:0.015-0.025.

[0014] Furthermore, in step (2), the mixed solution is transferred to a polytetrafluoroethylene-lined reactor and reacted at 130-160° C. for 8-12 hours, the precipitated powder in the reactor is collected, and the precipitated powder is washed with ethanol, and the precipitated powder after ethanol washing is dried at 55-65° C. for 10-14 hours.

[0015] Further, in step (3), the spherical Ni-MOF material and Ti3C2T X The mass ratio of the powder is 0.8-1.2:0.8-1.2.

[0016] Further, in step (4), the Ni-MOF / Ti3C2T X The mass ratio of the mixed powder to melamine is 0.8-1.6:1.

[0017] Furthermore, in step (4), the sintering temperature of the tubular furnace is 800-1000° C., and the sintering time is 2-4 hours.

[0018] Furthermore, the heating rate of the tubular furnace is 4-10°C / min.

[0019] Furthermore, in step (1), the solvent is N,N-dimethylformamide.

[0020] Furthermore, in step (1), the polyvinyl pyrrolidone is polyvinyl pyrrolidone-K30.

[0021] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0022] In this application, MXene, N-CNTs and Ni-MOF-derived Ni / C composite materials are combined, wherein the two-dimensional sheet-like MXenes are a two-dimensional metal carbide and nitride with a graphene-like structure, excellent conductivity and special electronic properties. In addition, a large number of functional groups, interfaces and inherent defects on the surface of MXenes contribute to the increase of polarization. In this application, doping N elements in carbon materials can introduce defects as polarization centers, provide defect / dipole polarization for the material, reduce impedance mismatch and achieve excellent wave absorption. The reasonable ratio of raw materials in this application can, on the one hand, introduce more heterogeneous interfaces to increase the polarization effect of the absorbing material; on the other hand, it can simultaneously bring into play the advantages of the three, reduce the filling amount of Ni / C composite materials in the collective, and achieve the optimization of comprehensive wave absorption performance.

[0023] The reasonable pyrolysis process in this application can optimize the microscopic morphology and structure of the finished product and further improve the microwave absorption performance of the finished product. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Example 2 Ni / C / Ti3C2T X Schematic diagram of / N-CNTs composite absorbing material. DETAILED DESCRIPTION

[0025] It should be understood that the present invention is not limited to the specific compositions, methods or schemes described herein. In addition, 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 the present invention belongs. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the scope of the present invention, which is limited only by the claims. The experimental methods used in the examples are conventional methods unless otherwise specified; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial sources.

[0026] Ni(NO3)2·6H2O: nickel nitrate hexahydrate;

[0027] H3BTC: trimesic acid;

[0028] DMF: N,N-dimethylformamide;

[0029] PVP K30: Polyvinylpyrrolidone-K30

[0030] Example 1

[0031] Preparation of Ni-MOF: Weigh 300 mg of Ni(NO3)2·6H2O, 100 mg of H3BTC, and 1 g of PVPK30 and dissolve them in 20 mL of DMF. Stir magnetically for 30 min until the solution is a uniform light green color. Transfer the mixed solution to a polytetrafluoroethylene-lined reactor, seal it, and place it in a drying oven at 150°C for 10 h. Collect the light green precipitate in the reactor, wash it with ethanol several times, and then dry it at 60°C for 12 h to obtain a spherical Ni-MOF material.

[0032] Ni / C / Ti3C2T X Preparation of / N-CNTs composite absorber: First, 100 mg of Ni-MOF powder and 100 mg of Ti3C2T X After the powder was fully ground, 100 mg of Ni-MOF / Ti3C2T X After being fully mixed with 100 mg of melamine, it was calcined in a tube furnace at 850 °C with N2 for 3 h to obtain Ni / C / Ti3C2T X / N-CNTs composite absorbing material, wherein the heating rate of the tube furnace is 5°C / min.

[0033] Example 2

[0034] (1) Preparation of Ni-MOF: Weigh 500 mg of Ni(NO3)2·6H2O, 100 mg of H3BTC, and 1 g of PVPK30 and dissolve them in 20 mL of DMF. Stir magnetically for 30 min until the solution is a uniform light green color. Transfer the mixed solution to a polytetrafluoroethylene-lined reactor, seal it, and place it in a drying oven at 150°C for 10 h. Collect the light green precipitate in the reactor, wash it with ethanol several times, and then dry it at 60°C for 12 h to obtain a spherical Ni-MOF material.

[0035] (2)Ni / C / Ti3C2T X Preparation of / N-CNTs composite absorber: First, 100 mg of Ni-MOF powder and 100 mg of Ti3C2T X After the powder was fully ground, 150 mg of Ni-MOF / Ti3C2T X After being fully mixed with 100 mg of melamine, the mixture was calcined in a tube furnace at 900 °C with N2 for 3 h to obtain Ni / C / Ti3C2T X / N-CNTs composite absorbing material, wherein the heating rate of the tube furnace is 8°C / min.

[0036] Comparative Example 1

[0037] Based on Example 2, Ni-MOF powder and Ti3C2T X The specific ratio of powder is:

[0038] (1) Preparation of Ni-MOF: Weigh 500 mg of Ni(NO3)2·6H2O, 100 mg of H3BTC, and 1 g of PVPK30 and dissolve them in 20 mL of DMF. Stir magnetically for 30 min until the solution is a uniform light green color. Transfer the mixed solution to a polytetrafluoroethylene-lined reactor, seal it, and place it in a drying oven at 150°C for 10 h. Collect the light green precipitate in the reactor, wash it with ethanol several times, and then dry it at 60°C for 12 h to obtain a spherical Ni-MOF material.

[0039] (2)Ni / C / Ti3C2T X Preparation of / N-CNTs composite absorber: First, 100 mg of Ni-MOF powder and 150 mg of Ti3C2T X After the powder was fully ground, 150 mg of Ni-MOF / Ti3C2T XAfter being fully mixed with 100 mg of melamine, the mixture was calcined in a tube furnace at 900 °C with N2 for 3 h to obtain Ni / C / Ti3C2T X / N-CNTs composite absorbing material, wherein the heating rate of the tube furnace is 8°C / min.

[0040] Comparative Example 2

[0041] The sintering temperature of the tubular furnace in step (2) is adjusted based on Example 2, specifically:

[0042] (1) Preparation of Ni-MOF: Weigh 500 mg of Ni(NO3)2·6H2O, 100 mg of H3BTC, and 1 g of PVPK30 and dissolve them in 20 mL of DMF. Stir magnetically for 30 min until the solution is a uniform light green color. Transfer the mixed solution to a polytetrafluoroethylene-lined reactor, seal it, and place it in a drying oven at 150°C for 10 h. Collect the light green precipitate in the reactor, wash it with ethanol several times, and then dry it at 60°C for 12 h to obtain a spherical Ni-MOF material.

[0043] (2)Ni / C / Ti3C2T X Preparation of / N-CNTs composite absorber: First, 100 mg of Ni-MOF powder and 100 mg of Ti3C2T X After the powder was fully ground, 150 mg of Ni-MOF / Ti3C2T X After being fully mixed with 100 mg of melamine, the mixture was calcined in a tube furnace at 900 °C with N2 for 4 h to obtain Ni / C / Ti3C2T X / N-CNTs composite absorbing material, wherein the heating rate of the tube furnace is 8°C / min.

[0044] Test Example 1:

[0045] The composite absorbing materials prepared in Example 1-2 and Comparative Example 1-2 were tested for S parameters using a vector network analyzer, and the reflection loss (RL) was calculated.

[0046] name Thickness(mm) RLmin(dB) Effective absorption band (GHz) Example 1 2.52 58.2 4.5 Example 2 1.75 65.1 6.5 Comparative Example 1 2.34 56.2 3.9 Comparative Example 2 2.60 50.4 4.2

[0047] The experimental results show that the composite absorbing material prepared in the present application has better absorbing performance.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a multi-layer spherical composite absorbing material, characterized in that: The following steps are involved: (1) adding nickel nitrate, trimesic acid and polyvinyl pyrrolidone into a solvent and mixing to prepare a mixed solution; (2) transferring the mixed solution to a polytetrafluoroethylene-lined reactor for reaction to obtain a spherical Ni-MOF material; (3) Spherical Ni-MOF materials and Ti3C2T X Powder mixing to obtain Ni-MOF / Ti3C2T X Mixing powders; (4) Ni-MOF / Ti3C2T X The mixed powder is mixed with melamine to obtain the melamine mixed powder, and the melamine mixed powder is transferred to a tubular furnace for sintering to obtain a finished product.

2. The method for preparing a multilayer spherical composite absorbing material according to claim 1, characterized in that: In step (1), the mass ratio of nickel nitrate, trimesic acid, polyvinyl pyrrolidone and solvent is 0.2-0.6:0.05-0.15:0.9-1.1:0.015-0.

025.

3. The method for preparing the multi-layer spherical composite absorbing material according to claim 1, characterized in that: In step (2), the mixed solution is transferred to a polytetrafluoroethylene-lined reactor and reacted at 130-160° C. for 8-12 hours, the precipitated powder in the reactor is collected, and the precipitated powder is washed with ethanol. The precipitated powder after ethanol washing is dried at 55-65° C. for 10-14 hours.

4. The method for preparing the multi-layer spherical composite absorbing material according to claim 1, characterized in that: In step (3), the spherical Ni-MOF material and Ti3C2T X The mass ratio of the powder is 1:0.8-1.

3.

5. The method for preparing the multi-layer spherical composite absorbing material according to claim 1, characterized in that: In step (4), the Ni-MOF / Ti3C2T X The mass ratio of the mixed powder to melamine is 0.8-1.6:

1.

6. The method for preparing the multi-layer spherical composite absorbing material according to claim 1, characterized in that: In step (4), the sintering temperature in the tubular furnace is 800-1000° C., and the sintering time is 2-4 hours.

7. The method for preparing the multi-layer spherical composite absorbing material according to claim 6, characterized in that: The heating rate of the tubular furnace is 5-10°C / min.

8. The method for preparing the multi-layer spherical composite absorbing material according to claim 1, characterized in that: In step (1), the solvent is N,N-dimethylformamide.

9. The method for preparing the multi-layer spherical composite absorbing material according to claim 1, characterized in that: In step (1), the polyvinyl pyrrolidone is polyvinyl pyrrolidone-K30.

10. A multi-layer spherical composite absorbing material, characterized in that: The method is prepared according to any one of claims 1 to 9.

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