Preparation method and application of pointed-cone-shaped wave-absorbing foam based on M-bit solid solution MXene

Abstract

The invention belongs to the technical field of electromagnetic wave darkrooms and electromagnetic wave shielding materials, and particularly provides a preparation method and application of pointed-cone-shaped wave-absorbing foam based on an M-bit solid solution MXene, which are used for solving the problem of test space compression of a terahertz test box caused by a wave-absorbing material. The wave-absorbing material which is thin in thickness, light in weight and excellent in wave-absorbing performance is prepared by utilizing the excellent electrical conductivity of the M-bit solid solution MXene and the synergistic effect of bimetals and combining the design of a pointed-cone-shaped foam structure; compared with a traditional pointed-cone-shaped wave-absorbing material, the material can efficiently absorb and shield terahertz electromagnetic waves under the condition that the thickness is small, and the available space in a portable terahertz test box can be effectively expanded when the material is applied to the portable terahertz test box; meanwhile, the wave-absorbing foam has the characteristics of strong processability and tight contact, can prevent terahertz waves from leaking from gaps, and realizes accurate control of electromagnetic waves in a complex test environment through optimal design of the structure and components.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic anechoic chambers and electromagnetic shielding materials, and specifically provides a preparation method of a tapered absorbing foam based on M-site solid solution MXene and its application in a portable terahertz test chamber. Background Art

[0002] With the rapid development of technologies such as electronics, telecommunications, and medical devices, the demand for electromagnetic measurements in the terahertz band is increasing day by day, posing higher requirements for the electromagnetic interference (EMI) shielding and absorbing performance of the test environment. As a key device, a terahertz test chamber needs to effectively shield external electromagnetic interference and absorb the electromagnetic wave signals generated inside. In traditional terahertz test chambers or anechoic chambers, polyurethane foam tapered arrays are mostly used as absorbing materials. To achieve a better absorbing effect, a relatively large thickness and a relatively high tapered structure are usually required, which significantly compresses the available space inside the test chamber. At the same time, the equipment layout in traditional anechoic chambers is dense and the internal space is limited, further exacerbating the complexity of the test environment and restricting its application in high-precision terahertz electromagnetic tests.

[0003] To address the above problems, two-dimensional transition metal carbides (nitrides) (MXenes) have become a research hotspot in the field of electromagnetic shielding and absorbing materials due to their excellent metallic conductivity, high specific surface area, rich surface functional groups, and easy solution processing. Therefore, the present invention provides a preparation method of a tapered absorbing foam based on M-site solid solution MXene ((Ti y M 1-y )3C2T x , 0 < y < 1, where the M-site element is Nb, Cr, V, or Mo), and the prepared tapered absorbing foam can be applied to a terahertz test chamber to solve the problem of test space compression caused by the absorbing material in the terahertz test chamber. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a tapered absorbing foam based on M-site solid solution MXene and its application in a portable terahertz test chamber. The present invention utilizes the excellent conductivity and bimetallic synergistic effect of M-site solid solution MXene, combined with the design of the tapered foam structure, to prepare an absorbing material with a thin thickness, light weight, and excellent absorbing performance. Compared with traditional tapered absorbing materials, this material can achieve efficient absorption and shielding of terahertz electromagnetic waves at a relatively thin thickness. Applying it to a portable terahertz test chamber can effectively expand the available space inside the test chamber. At the same time, this absorbing foam has strong processability and close contact, can prevent terahertz waves from leaking through the gaps, and through the optimized design of the structure and composition, can achieve precise control of electromagnetic waves in a complex test environment.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A preparation method of a conical wave-absorbing foam based on M-site solid solution MXene, characterized by comprising the following steps:

[0007] S1. Prepare an M-site solid solution Mxene suspension, taking Ti2NbC2T x as an example;

[0008] S1.1. Mix deionized water, hydrochloric acid (HCl) and hydrofluoric acid (HF) according to a volume ratio of 2:4:1 to obtain an acidic etching solution;

[0009] S1.2. Add MAX phase powder to the acidic etching solution and magnetically stir for 24 h to 48 h to complete etching, obtaining an MXene acidic solution;

[0010] S1.3. Repeatedly centrifuge and wash the MXene acidic solution with deionized water until the pH value of the supernatant is 5 to 7, obtaining a multi-layer M-site solid solution MXene material;

[0011] S1.4. Disperse the multi-layer M-site solid solution Mxene material into a LiCl solution, stir for 1 h to 4 h to complete intercalation, and then repeatedly centrifuge and wash multiple times, taking the black precipitate;

[0012] S1.5. Disperse the black precipitate in deionized water to obtain a uniformly dispersed M-site solid solution Mxene suspension;

[0013] S2. Immerse the conical polyurethane sponge foam in the M-site solid solution Mxene suspension for 30 min to 60 min, and repeatedly squeeze the polyurethane sponge foam with tweezers no less than 3 times during the immersion process;

[0014] S3. Take out the conical polyurethane sponge foam and let it stand for 3 h to 4 h under normal temperature and pressure;

[0015] S4. Place the conical polyurethane sponge foam after standing in a vacuum drying oven at 60 °C for 12 h to 24 h to obtain a conical wave-absorbing foam based on M-site solid solution MXene.

[0016] Preferably, in step S1.1, the MAX phase powder specifically adopts (Ti y M 1-y )3AlC2T x , 0 < y < 1, where the M-site element is Nb, Cr, V or Mo.

[0017] Preferably, in step S1.2, 0.02 g to 0.08 g of MAX phase powder is added to each 1 mL of the etching solution.

[0018] Preferably, in step S1.4, the concentration of the LiCl solution is 0.000024 mol / mL to 0.0007 mol / mL, and 50 mL to 150 mL of the LiCl solution corresponds to every 1 g of the MAX phase powder.

[0019] Preferably, in step 1.5, the mass concentration of MXene in the M-site solid solution Mxene suspension is 0.1 mg / mL to 15 mg / mL.

[0020] Furthermore, the present invention also provides the application of the above-mentioned conical absorbing foam based on the M-site solid solution MXene, which is characterized in that the conical absorbing foam of MXene is adhered to all inner wall surfaces of the terahertz test chamber as an absorbing layer.

[0021] Preferably, the terahertz test chamber further includes: a housing, a chamber door, an antenna port and an electric rotary displacement stage. The chamber door is connected to the housing through a hinge to jointly form the chamber body of the test chamber; the antenna port is arranged on the side wall of the housing for installing a terahertz transmitting antenna and a receiving antenna; the electric rotary displacement stage is connected to the sample to be tested through a low-scattering thin rod or a thin wire.

[0022] Based on the above technical solutions, the beneficial effects of the present invention are as follows:

[0023] The present invention provides a preparation method and application of a conical absorbing foam based on an M-site solid solution MXene. The M-site solid solution Mxene adopts (Ti y M 1-y )3C2T x, 0 < y < 1, where the M-site element is Nb, Cr, V, or Mo; a tapered absorbing foam is prepared based on the M-site solid solution Mxene. When it is applied to the inner wall of a terahertz test chamber as a terahertz absorbing material, it can provide excellent electromagnetic shielding performance at a relatively thin thickness, thereby solving the problem of the compression of the available test space caused by the absorbing material; moreover, by utilizing the excellent absorbing performance of the tapered absorbing foam, it can absorb and reduce the reflection of terahertz waves, improve the measurement accuracy of the terahertz test chamber, and at the same time reduce the interference of external electromagnetic waves, the formation of standing waves, and the reflection of electromagnetic waves inside the chamber, effectively reducing the data errors generated during the test and enhancing the scientificity and accuracy of the test; furthermore, the tapered absorbing foam material inside the terahertz test chamber has the advantages of excellent shielding / absorbing performance, light weight, thin thickness, strong processability, and tight contact at the contact points, which can effectively prevent the leakage of terahertz waves from the gaps and achieve efficient absorption of terahertz electromagnetic waves; on this basis, through reasonable design and optimization, a portable terahertz test chamber based on MXene tapered absorbing foam has achieved effective shielding of terahertz electromagnetic waves and precise control of the internal electromagnetic environment, providing a reliable and efficient solution for electromagnetic measurement in the terahertz band. Brief Description of the Drawings

[0024] Figure 1 XRD characterization diagram of the two-dimensional material Ti2NbC2T prepared in the present invention; x

[0025] Figure 2 SEM characterization diagrams of the monolayer and multilayer of the two-dimensional material Ti2NbC2T prepared in the present invention; x

[0026] Figure 3 Physical diagram of the terahertz test chamber involved in the present invention;

[0027] Figure 4 Front view schematic diagram of the terahertz test chamber involved in the present invention;

[0028] Figure 5 Right view schematic diagram of the terahertz test chamber involved in the present invention;

[0029] Figure 6 Left view schematic diagram of the terahertz test chamber involved in the present invention;

[0030] Figure 7 Top view schematic diagram of the terahertz test chamber involved in the present invention;

[0031] Figure 8 Test result diagram of the reflection performance of the terahertz test chamber involved in the present invention for electromagnetic waves in the terahertz band;

[0032] Figures 3 to 7 Middle: 1 is the outer shell, 2 is the box door, 3 is the antenna port, 4 is the electric rotation stage, and 5 is the pointed cone-shaped absorbing foam. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0034] Example 1

[0035] This embodiment provides a method for preparing a pointed cone-shaped wave-absorbing foam based on an M-site solid solution MXene, wherein the M-site solid solution MXene is specifically: (Ti y M 1-y )3C2T x , 0<y<1, wherein the M-site element is Nb, Cr, V or Mo, and in this embodiment is specifically Ti2NbAlC2; the M-site solid solution MXene two-dimensional nano suspension is combined with polyurethane foam to prepare a terahertz absorbing material based on a three-dimensional MXene composite structure; the specific steps are as follows:

[0036] S1. Preparation (Ti y M 1-y )3C2T x Nanosuspension, based on Ti2NbC2T x For example;

[0037] S1.1, mixing deionized water, hydrochloric acid (HCl) and hydrofluoric acid (HF) in a volume ratio of 2:4:1 to obtain an acidic etching solution;

[0038] S1.2, slowly add MAX((Ti y M 1-y )3AlC2) phase powder was added to prevent high temperature caused by adding powder too quickly. The Al layer in the MAX phase was etched away by acid through magnetic stirring for 24 hours to obtain MXene ((Ti y M 1-y )3C2T x ) acidic solution, wherein 0.02 g of MAX((Ti y M 1-y )3AlC2) phase powder;

[0039] S1.3, the MXene acid solution was repeatedly centrifuged and washed with deionized water until the pH value of the supernatant was 5, and a multilayer M-site solid solution MXene ((Ti y M 1-y )3C2T x )Material;

[0040] S1.4. Disperse the black precipitate in the multilayer M - layer solid - solution MXene ((Ti y M 1-y )3C2T x ) into the LiCl solution, stir for 1 h, and then centrifuge and wash repeatedly for multiple times until the supernatant becomes turbid and black. Among them, the concentration of the LiCl solution is 0.000024 mol / mL, and for every 1 g of the (Ti y M 1-y )3AlC2 powder, it corresponds to 50 mL of the LiCl solution;

[0041] S1.5. Disperse the black precipitate obtained in step S4 in deionized water to obtain a uniformly dispersed (Ti y M 1-y )3C2T x nano - suspension. Among them, the mass concentration of (Ti y M 1-y )3C2T x in the (Ti y M 1-y )3C2T x nano - suspension is 0.1 mg / mL;

[0042] S2. Immerse the tapered polyurethane sponge foam in the (Ti y M 1-y )3C2T x nano - suspension for 30 minutes, and repeatedly squeeze the polyurethane sponge foam with tweezers no less than 3 times during the immersion process;

[0043] S3. Take out the tapered polyurethane sponge foam and let it stand at normal temperature and pressure for 3 h until no MXene nano - black solution drips from the surface;

[0044] S4. Place the tapered polyurethane sponge foam after standing in a vacuum drying oven at 60 °C for 12 h to obtain a tapered wave - absorbing foam based on M - layer solid - solution MXene.

[0045] Test the prepared M - layer solid - solution MXene two - dimensional material Ti2NbC2T x . The XRD characterization diagram is as Figure 1 shown, and the SEM characterization diagrams of single - layer and multi - layer are as Figure 2 shown. It can be seen from the figure that the (002) peak of the tested sample in the XRD characterization diagram is significant, indicating that the used nano - material has a layered structure. At the same time, the SEM characterization diagram also proves its layered structure.

[0046] Example 2

[0047] This embodiment provides a method for preparing a pointed cone-shaped wave-absorbing foam based on M-site solid solution MXene, and the specific steps are as follows:

[0048] S1. Preparation (Ti y M 1-y )3C2T x Nanosuspension, based on Ti2NbC2T x For example;

[0049] S1.1, mixing deionized water, hydrochloric acid (HCl) and hydrofluoric acid (HF) in a volume ratio of 2:4:1 to obtain an acidic etching solution;

[0050] S1.2, slowly add MAX((Ti y M 1-y )3AlC2) phase powder was added to prevent high temperature caused by adding powder too quickly. The Al layer in the MAX phase was etched away by acid by magnetic stirring for 36 hours to obtain MXene ((Ti y M 1-y )3C2T x ) acidic solution, wherein 0.06 g of MAX((Ti y M 1-y )3AlC2) phase powder;

[0051] S1.3, the MXene acid solution was repeatedly centrifuged and washed with deionized water until the pH value of the supernatant was 6.4, and a multilayer M-site solid solution MXene ((Ti y M 1-y )3C2T x )Material;

[0052] S1.4. Multilayer M-site solid solution MXene ((Ti y M 1-y )3C2T x ) was dispersed into LiCl solution, stirred for 3.5 h, and then centrifuged and washed several times until the supernatant became turbid and black. The concentration of LiCl solution was 0.000525 mol / mL. y M 1-y )3AlC2 powder corresponds to 110mL of LiCl solution;

[0053] S1.5, dispersing the black precipitate obtained in step S4 in deionized water to obtain a uniformly dispersed (Ti y M 1-y )3C2T x Nanosuspension, wherein (Ti y M 1-y )3C2Tx Nano-suspension (Ti y M 1-y )3C2T x The mass concentration is 7.85 mg / mL;

[0054] S2, soak the pointed cone polyurethane sponge foam in (Ti y M 1-y )3C2T x The immersion time in the nano suspension was 30 minutes, and the polyurethane sponge foam was repeatedly squeezed by tweezers for no less than 3 times during the immersion process;

[0055] S3, take out the pointed cone-shaped polyurethane sponge foam, and let it stand for 3.5 hours at normal temperature and pressure until no MXene nano black solution drips on the surface;

[0056] S4. Place the tapered polyurethane sponge foam in a vacuum drying oven at 60° C. for 16 hours to obtain a tapered absorbing foam based on the M-site solid solution MXene.

[0057] Example 3

[0058] This embodiment provides a method for preparing a pointed cone-shaped wave-absorbing foam based on M-site solid solution MXene, and the specific steps are as follows:

[0059] S1. Preparation (Ti y M 1-y )3C2T x Nanosuspension, based on Ti2NbC2T x For example;

[0060] S1.1, mixing deionized water, hydrochloric acid (HCl) and hydrofluoric acid (HF) in a volume ratio of 2:4:1 to obtain an acidic etching solution;

[0061] S1.2, slowly add MAX((Ti y M 1-y )3AlC2) phase powder was added to prevent high temperature caused by adding powder too quickly. The Al layer in the MAX phase was etched away by acid through magnetic stirring for 48 hours to obtain MXene ((Ti y M 1-y )3C2T x ) acidic solution, wherein 0.08 g of MAX((Ti y M 1-y )3AlC2) phase powder;

[0062] S1.3, the MXene acid solution was repeatedly centrifuged and washed with deionized water until the pH value of the supernatant was 7, and a multilayer M-site solid solution MXene ((Tiy M 1-y )3C2T x ) Material;

[0063] S1.4. Disperse the black precipitate in the multilayer M-site solid solution MXene ((Ti y M 1-y )3C2T x ) into the LiCl solution, stir for 4 h, and then repeatedly centrifuge and wash several times until the supernatant becomes turbid and black. Among them, the concentration of the LiCl solution is 0.000525 mol / mL, and for every 1 g of (Ti y M 1-y )3AlC2 powder, it corresponds to 150 mL of the LiCl solution;

[0064] S1.5. Disperse the black precipitate obtained in step S4 in deionized water to obtain a uniformly dispersed (Ti y M 1-y )3C2T x nano-suspension. Among them, the mass concentration of (Ti y M 1-y )3C2T x in the nano-suspension is 15 mg / mL; y M 1-y )3C2T x x

[0065] S2. Immerse the tapered polyurethane sponge foam in the (Ti y M 1-y )3C2T x nano-suspension for 30 minutes, and repeatedly squeeze the polyurethane sponge foam with tweezers no less than 3 times during the immersion process;

[0066] S3. Take out the tapered polyurethane sponge foam and let it stand at normal temperature and pressure for 3.7 h until no MXene nano-black solution drips from the surface;

[0067] S4. Place the tapered polyurethane sponge foam after standing in a vacuum drying oven at 60 °C for 24 h to obtain a tapered wave-absorbing foam based on the M-site solid solution MXene.

[0068] Example 4

[0069] Based on the MXene tapered wave-absorbing foam prepared in Examples 1 to 3, this example provides an application of the MXene tapered wave-absorbing foam in a terahertz test chamber. The MXene tapered wave-absorbing foam 5 adheres to all the inner wall surfaces of the portable terahertz test chamber, which is used to absorb and reduce the reflection of terahertz waves, improve the measurement accuracy, and at the same time reduce the interference of external electromagnetic waves, the formation of standing waves, and the reflection of electromagnetic waves inside the chamber, thereby effectively reducing the data error generated during the test and enhancing the scientificity and accuracy of the test. As Figures 3 to 7 shown, the terahertz test chamber further includes: a housing 1, a chamber door 2, an antenna port 3, and an electric rotary displacement stage 4; the chamber door 2 is connected to the housing 1 through a hinge for easy opening and closing operations, and the housing 1 is made of a high-conductivity metal material; the antenna port 3 is used to place a terahertz transmitting antenna and a receiving antenna for measuring the reflection and transmission performance of the sample; the electric rotary displacement stage 4 is connected to the sample to be measured through a low-scattering thin rod or thin wire; the chamber door 2 and the housing 1 form the main structure of the chamber. Among them, the unused antenna ports are filled with the MXene tapered wave-absorbing foam 5 to maintain the integrity of the chamber and prevent external electromagnetic waves from interfering with the internal measurement environment through the antenna ports.

[0070] The performance of the chamber and the tapered wave-absorbing material was tested through experiments. In the W band of 75 - 110 GHz, with a vector network analyzer of model AV3672, a millimeter-wave frequency extension module of model AV3640A, two S-parameter test modules of model AV3645A, and a Hengda microwave standard gain horn antenna, the electromagnetic waves were incident from one antenna port 3 on the same side of the chamber and received by the other antenna port 3 to observe the return loss level of the chamber. The test process is as follows: During the test, the electromagnetic waves in the terahertz frequency band are emitted from the transmitting antenna at one end, pass through the sample to be measured and are reflected, and then received by the receiving antenna at the other end. The electromagnetic characteristics of the sample to be measured, such as reflectivity and transmittance, can be obtained by calculating the intensity relationship between the emitted signal and the received signal.

[0071] As Figure 8 shown, the figure shows the test results of the reflection performance of the terahertz test chamber for electromagnetic waves in the terahertz frequency band. It can be seen from the figure that by comparing the two test curves of the tapered foam and the original chamber, fixing the tapered foam attached with the solid solution MXene nanomaterial inside the chamber can significantly improve the shielding performance of the terahertz test chamber; and by comparing the test curves of the front and back of the taper, it can be known that the taper structure designed in the present invention is conducive to the absorption of electromagnetic waves, thereby improving the shielding performance of the terahertz test chamber.

[0072] The above are only specific embodiments of the present invention. Any feature disclosed in this specification, unless specifically described, can be replaced by other equivalent or alternative features with similar purposes; all the disclosed features, or all the steps in any method or process, except for mutually exclusive features and / or steps, can be combined in any manner.

Claims

1. A method for preparing a pointed cone-shaped wave-absorbing foam based on M-site solid solution MXene, characterized in that: The following steps are involved: S1. Preparation of M-site solid solution Mxene suspension with Ti2NbC2T x For example; S1.1, mixing deionized water, hydrochloric acid (HCl) and hydrofluoric acid (HF) in a volume ratio of 2:4:1 to obtain an acidic etching solution; S1.2, adding MAX phase powder to the acidic etching solution, magnetically stirring for 24h to 48h to complete the etching, and obtaining a MXene acidic solution; S1.3, repeatedly centrifugally washing the MXene acid solution with deionized water until the pH value of the supernatant is 5-7, and obtaining a multilayer M-site solid solution MXene material; S1.4, disperse the multilayer M-site solid solution Mxene material into the LiCl solution, stir for 1h to 4h to complete the intercalation, then centrifuge and wash repeatedly for multiple times to obtain a black precipitate; S1.5, dispersing the black precipitate in deionized water to obtain a uniformly dispersed M-site solid solution Mxene suspension; S2, immersing the pointed cone-shaped polyurethane sponge foam in the M-site solid solution Mxene suspension for 30 min to 60 min, and repeatedly squeezing the polyurethane sponge foam with tweezers for at least 3 times during the immersion process; S3, take out the pointed cone-shaped polyurethane sponge foam, and let it stand for 3h to 4h under normal temperature and pressure; S4. Place the tapered polyurethane sponge foam in a vacuum drying oven at 60° C. for 12 to 24 hours to obtain a tapered absorbing foam based on the M-site solid solution MXene.

2. The method for preparing the pointed cone-shaped microwave-absorbing foam based on the M-site solid solution MXene according to claim 1, characterized in that: In step S1.1, the MAX phase powder is specifically (Ti y M 1-y )3C2T x , 0<y<1, where the M-bit element is Nb, Cr, V or Mo.

3. The method for preparing the pointed cone-shaped wave-absorbing foam based on the M-site solid solution MXene according to claim 1, characterized in that: In step S1.2, 0.02 g to 0.08 g of MAX phase powder is added to every 1 mL of etching solution.

4. The method for preparing a pointed cone-shaped wave-absorbing foam based on M-site solid solution MXene according to claim 1, characterized in that: In step S1.4, the concentration of the LiCl solution is 0.000024 mol / mL to 0.0007 mol / mL, and every 1 g of MAX phase powder corresponds to 50 mL to 150 mL of LiCl solution.

5. The method for preparing the pointed cone-shaped microwave-absorbing foam based on the M-site solid solution MXene according to claim 1, characterized in that: In step 1.5, the mass concentration of MXene in the M-site solid solution MXene suspension is 0.1 mg / mL to 15 mg / mL.

6. An application of a pointed cone-shaped wave-absorbing foam based on M-site solid solution MXene, characterized in that: The pointed cone-shaped absorbing foam based on the M-site solid solution MXene described in claim 1 is adhered to all inner wall surfaces of the terahertz test box as an absorbing layer.

7. The use of the pointed cone-shaped wave-absorbing foam based on the M-site solid solution MXene according to claim 6, characterized in that: The terahertz test box also includes: an outer shell, a box door, an antenna port and an electric rotary displacement stage. The box door is connected to the outer shell by a hinge to form a box body of the test box together; the antenna port is arranged on the side wall of the outer shell for installing a terahertz transmitting antenna and a receiving antenna; the electric rotary displacement stage is connected to the sample to be tested by a low-scattering thin rod or thin wire.

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