Preparation method of flaky FeSiAl-coated MXene composite wave-absorbing material

Abstract

The invention discloses a preparation method of a flaky FeSiAl-coated MXene composite wave-absorbing material, and belongs to the technical field of electromagnetic wave absorbing materials. The preparation method comprises the following steps: firstly, preparing flaky FeSiAl metal powder and accordion-shaped MXene powder, then carrying out ultrasonic treatment and centrifugal treatment to obtain a single-few-layer MXene suspension, and finally, combining the single-few-layer MXene with the modified flaky FeSiAl with positive electricity by utilizing electrostatic self-assembly to form the FeSiAl-coated MXene composite wave-absorbing material. The characteristic that the surface of MXene is negatively charged is utilized, hexadecyl trimethyl ammonium bromide is adopted to modify the surface of flaky FeSiAl to enable the flaky FeSiAl to be positively charged, combination of the flaky FeSiAl and single-layer and few-layer MXene is achieved through the electrostatic self-assembly technology, the synergistic effect of electrical loss and magnetic loss is utilized, the composite structure increases more ways for conduction loss of electromagnetic waves, and the composite structure is used for preparing the composite material. And low-frequency broadband electromagnetic absorption is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic wave absorbing materials, and in particular relates to a method for preparing a flaky FeSiAl@MXene composite absorbing material. Background Art

[0002] The research on microwave absorbing materials began in the 1940s and was initially mainly used in the military field, such as radar stealth and electromagnetic protection. With the continuous development of high frequency and integration of electronic equipment systems, the problem of electromagnetic pollution has increasingly attracted public attention, and the application scope of microwave absorbing materials has gradually expanded to the civilian field, including wireless communication, electromagnetic compatibility and environmental protection. At present, microwave absorbing materials have become the core technology in many fields such as the electronic information industry, aerospace and biomedicine, and have important strategic significance. FeSiAl materials have high magnetic permeability due to their low hysteresis expansion coefficient and low magnetocrystalline anisotropy constant, which can meet the strict requirements of low-frequency electromagnetic absorbing materials in the civilian field. Flake FeSiAl materials have broken through the Snoke limit and further broadened the low-frequency absorption bandwidth. However, it is often difficult for a single absorber to achieve good impedance matching, resulting in limited absorption efficiency. Therefore, the introduction of a composite structure and the consideration of electromagnetic synergy can effectively improve the impedance matching problem, overcome the limitations of traditional materials such as single loss, improve their overall absorption performance, and meet higher requirements for application scenarios.

[0003] For FeSiAl absorbing materials, Harbin Institute of Technology (Mater. Today Commun., 2024, 111344) optimized the ball milling process and used zirconium oxide balls for ball milling in a polytetrafluoroethylene ball mill to obtain complete flaky FeSiAl particles with smooth surface and rounded edges. At a filling rate of 70wt%, the reflection loss (RL) of the material at a frequency of 3.48GHz reached -65.0dB. After annealing at 800℃, the effective absorption bandwidth (EAB) of the sample reached 3.35GHz (0.43-3.78GHz) at a thickness of 5mm. The University of Electronic Science and Technology of China (J.Alloys Compd., 2021, 888:161574) adopted the classic The method realizes the complete encapsulation of SiO2 on flaky FeSiAl. When the matching thickness of this material is 3.5 mm, the maximum RL at 1.0 GHz is -12.4 dB, and the EAB is 1.44 GHz, achieving efficient absorption of L-band electromagnetic waves, but the reflection loss is relatively low. Patent CN116093633A discloses a multi-layer coated FeSiAl composite magnetic wave absorbing material and its preparation method, which uses flaky FeSiAl magnetic wave absorbing powder with surface oxidation as the core and MOFs derivatives as the coating layer to form a composite structure. The RL of this material is about -41.6 dB at around 3.5 GHz, however, the matching thickness and effective absorption bandwidth (EAB) data are not reported. Patent CN114654823A discloses a Mn-Zn ferrite-FeSiAl composite wave absorbing material and its preparation method. By alternately stacking the Mn-Zn ferrite matching layer and the FeSiAl wave absorbing layer and then performing hot pressing, the Mn-Zn ferrite-FeSiAl composite wave absorbing material is prepared. When the thickness of this material is 2.5 mm, in the frequency range of 2 - 18 GHz, the RL reaches -19.35 dB (at 15.9 GHz), and the EAB is 6.3 GHz (11.7 - 18 GHz). Nanjing University (Mater. Sci Eng B, 2013, 178(16): 1005 - 1011) prepared flaky FeSiAl powder by mechanical ball milling and oxidized its surface with a mixed solution of absolute ethanol and hydrogen peroxide to regulate the electromagnetic parameters of the material. At a filling load of 35 vol%, the oxidized flaky powder has an RL of -39.67 dB at a thickness of 4 mm and a frequency of 1.40 GHz, but no relevant report on the EAB is made.

[0004] Although the above materials modify the surface of FeSiAl, to a certain extent, they optimize the impedance matching of the materials and improve the wave absorption performance. However, as a single absorber, FeSiAl only relies on magnetic loss to dissipate electromagnetic waves, resulting in a narrow absorption band and limited absorption intensity, and it is always difficult to obtain a wave absorbing material with excellent performance. Summary of the Invention

[0005] The object of the present invention is to propose a preparation method of a flaky FeSiAl@MXene composite wave absorbing material for the problems existing in the background technology. By utilizing the negatively charged characteristic of the surface of MXene, cetyltrimethylammonium bromide (CTAB) is used to modify the surface of flaky FeSiAl to make it positively charged, and the combination of flaky FeSiAl and single / multi-layer MXene is realized through electrostatic self-assembly technology. By utilizing the synergistic effect of electrical loss and magnetic loss, more paths for the conduction loss of electromagnetic waves are added to the composite structure, realizing low-frequency broadband electromagnetic absorption.

[0006] The core idea of ​​the present invention is to flaky FeSiAl spherical powder to give the alloy powder easy-to-surface characteristics. The shape anisotropy caused by the difference between the demagnetization field inside and outside the plane is conducive to breaking the snooker limit, so that the flaky alloy powder has a higher magnetic permeability. The thickness of the FeSiAl flakes after flaking is significantly reduced, which reduces the eddy current loss of the material, which is not good for the material's wave absorption performance. The two-dimensional structure of the single few-layer MXene gives it excellent electrical conductivity. The large specific surface area of ​​the flaky powder provides a place for the single few-layer MXene to be carried. The single few-layer MXene is evenly distributed on the surface of the flaky FeSiAl to form a complete current loop. In addition, the overlap between the single few-layer MXene in the entire composite material forms a large current loop between the FeSiAl sheets, resulting in a significant increase in the conductivity inside the composite material. In the alternating magnetic field, the increase in conductivity will increase the eddy current loss, thereby compensating for the eddy current loss of the material. In addition, there are a large number of polar groups (such as -OH, -F, -O, etc.) on the surface of single-layer MXene. The high dielectric properties enhance the polarization effect of the composite material. The composite of flaky FeSiAl and single-layer MXene provides a large number of interfaces inside the material. Under the action of the electric field, the polar groups on the MXene interface will undergo orientation polarization, which enhances the interaction between the interfaces inside the material, produces additional polarization, and then increases the loss of electromagnetic waves. By adjusting the amount of single-layer MXene to control the interlayer thickness, the layered structure can cause electromagnetic waves to reflect and lose multiple times between different layers, increasing energy absorption. The composite material formed by this multilayer structure can provide multiple absorption mechanisms at different wavelengths, effectively improving the absorption capacity.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a flaky FeSiAl@MXene composite absorbing material comprises the following steps:

[0009] Step 1. Preparation of FeSiAl flakes:

[0010] Commercially available FeSiAl powder was ball-milled to obtain flaky FeSiAl;

[0011] Step 2. Accordion-shaped MXene powder preparation:

[0012] The MAX phase precursor powder is added to the etching solution, stirred continuously to complete the etching reaction of the MAX phase, and the suspension is obtained by repeated centrifugation and washing until the pH value is neutral, and freeze-dried to obtain accordion-shaped MXene powder;

[0013] Step 3. Surface modification of FeSiAl flakes:

[0014] Add the flaky FeSiAl obtained in Step 1 to a CTAB (cetyltrimethylammonium bromide) solution, stir evenly to obtain a mixed solution, where 200 - 400 mL of the CTAB solution is added to every 1 g of the flaky FeSiAl; continuously wash to remove the excess CTAB, and dry to obtain the modified flaky FeSiAl;

[0015] Step 4. Preparation of few-layer MXene:

[0016] Ultrasonically treat the accordion-shaped MXene powder obtained in Step 2 in ethanol, then transfer it to a centrifuge for centrifugation, and collect the upper suspension to obtain a few-layer MXene suspension;

[0017] Step 5. Preparation of flaky FeSiAl@MXene composite:

[0018] Add the modified flaky FeSiAl obtained in Step 3 to deionized water for dispersion. After stirring and dispersing, add it to the few-layer MXene suspension obtained in Step 4. 30 - 110 mL of the few-layer MXene suspension is added to every 1 g of the modified flaky FeSiAl, and continuously stir for 10 - 18 h. After the reaction is completed, dry to obtain the flaky FeSiAl@MXene composite microwave absorption material.

[0019] Further, during the ball milling in Step 1, the mass ratio of the commercially available FeSiAl powder: balls: ethanol is (7 - 10):1:(1 - 2).

[0020] Further, the balls used in the ball milling in Step 1 are steel balls with a diameter of 3 - 7 mm, and the ball milling speed is 220 - 350 r / min.

[0021] Further, the MAX phase precursor powder in Step 2 is one of Ti3AlC2 and Ti2AlC; the etching solution is one of HF and the LiF + HCl mixed solution; the ratio of the MAX phase precursor powder to the etching solution is 1 g:(5 - 20) mL, that is, 5 - 20 mL of the etching solution is added to 1 g of the MAX phase precursor powder.

[0022] Further, in Step 3, the concentration of the CTAB solution is 1 - 4 mg / mL, and the stirring time is 1 - 4 h.

[0023] Further, in Step 4, the time for ultrasonic and centrifugation treatment is 1 - 4 h.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. A preparation method of a flaky FeSiAl@MXene composite microwave absorbing material provided by the present invention realizes the combination of flaky FeSiAl and monolayer or few-layer MXene through an electrostatic self-assembly technique, and utilizes the synergistic effect of electrical loss and magnetic loss, so that the composite structure provides more paths for the conduction loss of electromagnetic waves, realizes electromagnetic absorption in a low-frequency broadband, and simultaneously improves the impedance matching characteristics.

[0026] 2. The flaky FeSiAl@MXene composite microwave absorbing material prepared by the present invention has good low-frequency electromagnetic absorption characteristics: when the matching thickness is 5.0 mm and the frequency is 4.0 GHz, the minimum RL value of -58.66 dB is obtained; when the matching thickness is 4.0 mm, the effective absorption bandwidth reaches 3.24 GHz (4.00 - 7.24 GHz).

[0027] 3. The preparation method of a flaky FeSiAl@MXene composite microwave absorbing material provided by the present invention is simple in operation, low in cost and high in safety factor, which is beneficial to realizing large-scale batch production. Description of the Drawings

[0028] Figure 1 It is the SEM image of the flaky FeSiAl@MXene composite microwave absorbing material prepared in Example 1;

[0029] Figure 2 It is the reflection loss diagram of the flaky FeSiAl@MXene composite microwave absorbing material prepared in Example 1;

[0030] Figure 3 It is the SEM image of the flaky FeSiAl@MXene composite microwave absorbing material prepared in Example 2;

[0031] Figure 4 It is the reflection loss diagram of the flaky FeSiAl@MXene composite microwave absorbing material prepared in Example 2;

[0032] Figure 5 It is the SEM image of the flaky FeSiAl microwave absorbing material prepared in the comparative example;

[0033] Figure 6 It is the reflection loss diagram of the flaky FeSiAl microwave absorbing material prepared in the comparative example. Detailed Embodiments

[0034] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and the drawings.

[0035] Example 1

[0036] A preparation method of a flaky FeSiAl@MXene composite microwave absorbing material includes the following steps:

[0037] Step 1. Preparation of flaky FeSiAl:

[0038] Put 100 g of commercially available FeSiAl powder, 1000 g of bearing steel balls and 1500 mL of ethanol into a ball mill jar, and ball mill at a speed of 241 r / min for 2 h to obtain flaky FeSiAl;

[0039] Step 2. Preparation of accordion-shaped MXene powder:

[0040] Add 1.0 g of Ti3AlC2 powder (400 mesh, purity ≥ 99.9%) to 20 mL of hydrofluoric acid solution with a concentration of 40%, and continuously stir at 25 °C for 48 h to etch the Al layer; Centrifuge and wash the product with deionized water, use a speed of 4500 rpm, centrifuge and wash for 5 min each time, and continue washing until the pH value is neutral, then freeze-dry for 48 h to obtain accordion-shaped MXene powder;

[0041] Step 3. Surface modification of flaky FeSiAl:

[0042] Add 300 mg of the flaky FeSiAl obtained in Step 1 to 100 mL of CTAB (cetyltrimethylammonium bromide) solution with a concentration of 2 mg / mL, and ultrasonicate for 90 min to obtain a mixture; After pouring off the supernatant, wash repeatedly with deionized water to remove the excess CTAB, and dry for 6 h to obtain the modified flaky FeSiAl;

[0043] Step 4. Preparation of single- and few-layer MXene:

[0044] Ultrasonicate 1.0 g of the accordion-shaped MXene powder obtained in Step 3 in 50 mL of ethanol for 90 min, then transfer it to a centrifuge and centrifuge at a speed of 3000 rpm for 1 h, collect the upper suspension to obtain a single- and few-layer MXene suspension;

[0045] Step 5. Preparation of flaky FeSiAl@MXene composite:

[0046] Add 300 mg of the modified flaky FeSiAl obtained in Step 3 to deionized water for dispersion. After stirring and dispersing, add it to 15 mL of the single- and few-layer MXene suspension obtained in Step 4, continuously stir for 15 h. After the reaction is completed, dry it to obtain the flaky FeSiAl@MXene composite microwave absorbing material.

[0047] Mix the flaky FeSiAl@MXene composite microwave absorbing material obtained in Step 5 with paraffin in a mass ratio of 4:1, press it into a ring with an outer diameter of 7 mm, an inner diameter of 3 mm, and a thickness of 3 mm, and perform microwave absorption performance testing.

[0048] Figure 1 SEM image of the flaky FeSiAl@MXene composite microwave absorbing material prepared in Example 1. It can be seen that few-layer MXene is adsorbed on the flaky FeSiAl to obtain a composite structure.

[0049] Figure 2 Reflection loss diagram of the flaky FeSiAl@MXene composite microwave absorbing material prepared in Example 1. As can be seen from the figure, the best performance of the sample is as follows: when the matching thickness is 4.0 mm, the effective absorption bandwidth reaches 1.09 GHz (6.21 - 7.30); when the matching thickness is 5.0 mm, the minimum RL value of -13.85 dB is obtained at a frequency of 5.45 GHz, indicating that the absorption rate of electromagnetic waves exceeds 99%, and the material meets the broadband absorption requirements.

[0050] Example 2

[0051] A preparation method of a flaky FeSiAl@MXene composite microwave absorbing material, comprising the following steps:

[0052] Step 1. Preparation of flaky FeSiAl:

[0053] Put 100 g of commercially available FeSiAl powder, 1000 g of bearing steel balls and 1500 mL of ethanol into a ball milling tank, and ball mill at a speed of 241 r / min for 2 h to obtain flaky FeSiAl.

[0054] Step 2. Preparation of accordion-like MXene powder:

[0055] Add 1.0 g of Ti3AlC2 powder (400 mesh, purity ≥ 99.9%) to 20 mL of hydrofluoric acid solution with a concentration of 40%, and continuously stir at 25 °C for 48 h to etch the Al layer; centrifuge and wash the product with deionized water at a speed of 4500 rpm for 5 min each time, and continue washing until the pH value is neutral, and freeze-dry for 48 h to obtain accordion-like MXene powder.

[0056] Step 3. Surface modification of flaky FeSiAl:

[0057] Add 300 mg of the flaky FeSiAl obtained in Step 1 to 100 mL of CTAB (cetyltrimethylammonium bromide) solution with a concentration of 2 mg / mL, and ultrasonicate for 90 min to obtain a mixed solution; after pouring off the supernatant, repeatedly wash with deionized water to remove the excess CTAB, and dry for 6 h to obtain the modified flaky FeSiAl.

[0058] Step 4. Preparation of few-layer MXene:

[0059] Ultrasonically disperse 1.0 g of the accordion-shaped MXene powder obtained in step 3 in 50 mL of ethanol for 90 min, then transfer it to a centrifuge and centrifuge at 3000 rpm for 1 h. Collect the upper suspension to obtain a single- and few-layer MXene suspension;

[0060] Step 5. Preparation of flaky FeSiAl@MXene composite material:

[0061] Disperse 300 mg of the modified flaky FeSiAl obtained in step 3 in deionized water. After stirring and dispersing, add it to 25 mL of the single- and few-layer MXene suspension obtained in step 4, and continuously stir for 18 h. After the reaction is completed, dry it to obtain the flaky FeSiAl@MXene composite absorbing material.

[0062] Mix the flaky FeSiAl@MXene composite absorbing material obtained in step 5 with paraffin in a mass ratio of 4:1, and press it into a ring with an outer diameter of 7 mm, an inner diameter of 3 mm, and a thickness of 3 mm for microwave absorption performance testing.

[0063] Figure 3 Figure [ID number] is the SEM image of the flaky FeSiAl@MXene composite absorbing material prepared in Example 2. It can be seen that single- and few-layer MXene is adsorbed on flaky FeSiAl to obtain a composite structure.

[0064] Figure 4 Figure [ID number] is the reflection loss diagram of the flaky FeSiAl@MXene composite absorbing material prepared in Example 2. As can be seen from the figure, the best performance of the sample is as follows: when the matching thickness is 4.0 mm, the effective absorption bandwidth reaches 3.24 GHz (4.00 - 7.24 GHz); when the matching thickness is 5.0 mm, the minimum RL value of -58.66 dB is obtained at a frequency of 4.0 GHz, indicating that the absorption rate of electromagnetic waves exceeds 99%, and the material meets broadband absorption.

[0065] Comparative example

[0066] Set a comparative experiment for the above examples. Without considering the composite with MXene, mix the dried flaky FeSiAl material with paraffin in a ratio of 4:1, press it into a ring with an outer diameter of 7 mm, an inner diameter of 3 mm, and a thickness of 3 mm, and conduct microwave absorption performance testing.

[0067] Figure 5 Figure [ID number] is the SEM image of the flaky FeSiAl absorbing material prepared in the comparative example.

[0068] Figure 6The reflection loss diagram of the flaky FeSiAl microwave absorbing material prepared as a comparative example. As can be seen from the figure, the optimal performance is as follows: when the matching thickness is 2.5 mm, the effective absorption bandwidth reaches 3.12 GHz (4.74 - 7.86 GHz); when the matching thickness is 5.0 mm, the minimum RL value of -21.56 dB is obtained at a frequency of 2.38 GHz.

[0069] The above-described embodiments merely represent specific embodiments of the present invention, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A method for preparing a flaky FeSiAl@MXene composite absorbing material, characterized in that: The following steps are involved: Step 1. Preparation of FeSiAl flakes: The FeSiAl powder is ball-milled to obtain flaky FeSiAl; Step 2. Accordion-shaped MXene powder preparation: Add the MAX phase precursor powder into the etching solution, continue stirring to complete the etching reaction of the MAX phase, centrifuge to obtain a suspension, and dry to obtain an accordion-shaped MXene powder; Step 3. Surface modification of FeSiAl flakes: The flaky FeSiAl obtained in step 1 is added to the CTAB solution, and stirred evenly to obtain a mixed solution, wherein 200 to 400 mL of the CTAB solution is added to every 1 g of the flaky FeSiAl; washed and dried to obtain the modified flaky FeSiAl; Step 4. Preparation of single few-layer MXene: The accordion-shaped MXene powder obtained in step 2 is ultrasonically treated in ethanol, centrifuged, and the upper suspension is collected to obtain a single few-layer MXene suspension; Step 5. Preparation of FeSiAl@MXene composite material: The flaky FeSiAl modified in step 3 is added into deionized water, stirred and dispersed, and then added into the single few-layer MXene suspension obtained in step 4. 30 to 110 mL of the single few-layer MXene suspension is added into every 1 g of the modified flaky FeSiAl, stirred, and dried after the reaction is completed to obtain the flaky FeSiAl@MXene composite absorbing material.

2. The method for preparing a flaky FeSiAl@MXene composite absorbing material according to claim 1, characterized in that: During ball milling in step 1, the mass ratio of FeSiAl powder: ball: ethanol is (7-10):1:(1-2).

3. The method for preparing a flaky FeSiAl@MXene composite absorbing material according to claim 1, characterized in that: The balls used in the ball milling in step 1 are steel balls with a diameter of 3 to 7 mm, and the ball milling speed is 220 to 350 r / min.

4. The method for preparing a flaky FeSiAl@MXene composite absorbing material according to claim 1, characterized in that: In step 2, the MAX phase precursor powder is one of Ti3AlC2 and Ti2AlC; the etching solution is one of HF and LiF+HCl mixed solution; the ratio of MAX phase precursor powder to etching solution is 1g: (5-20)mL.

5. The method for preparing a flaky FeSiAl@MXene composite absorbing material according to claim 1, characterized in that: In step 3, the concentration of the CTAB solution is 1 to 4 mg / mL, and the stirring time is 1 to 4 h.

6. The method for preparing a flaky FeSiAl@MXene composite absorbing material according to claim 1, characterized in that: In step 4, the time of ultrasonic and centrifugal treatment is 1 to 4 hours.

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