Terahertz wave-absorbing fabric and preparation method thereof

Abstract

The invention belongs to the field of wave-absorbing materials, and discloses a terahertz wave-absorbing fabric and a preparation method thereof. The terahertz wave-absorbing fabric comprises a conductive fiber porous array layer, a middle dielectric layer and a dense conductive cloth layer, the middle dielectric layer is arranged on one side of the conductive cloth layer; and the conductive fiber porous array layer is arranged on one side, far away from the conductive cloth layer, of the dielectric layer to form a three-layer composite wave-absorbing structure. According to the terahertz wave-absorbing fabric, the middle dielectric layer arranged on one side of the conductive cloth layer and the conductive fiber porous array layer arranged on the side, away from the conductive cloth layer, of the middle dielectric layer form a three-layer composite wave-absorbing structure, so that broadband, efficient and flexible wave absorption of the 0.1-2 THz wave band is achieved; the application requirements of wearing, stealth protection, electromagnetic compatibility and the like are met, and the absorptivity in a 50% frequency band reaches 0.9; and the fabric is distinct in structural hierarchy, easy to prepare, simple in structure and low in cost, and can be realized by utilizing a textile technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wave-absorbing materials, in particular to a terahertz wave-absorbing fabric and a preparation method thereof. BACKGROUND

[0002] With the rapid development of electronic technology and terahertz technology, the application of electromagnetic waves in the fields of wireless communication, safety detection, biological imaging, etc. is becoming increasingly widespread, and the corresponding high-frequency electromagnetic radiation and interference problems are also becoming increasingly prominent, which puts forward higher requirements for life health, normal operation of electronic equipment and stealth protection. Therefore, developing a wave-absorbing material that can achieve efficient broadband absorption in the terahertz frequency band and has the characteristics of flexibility, lightness, tailorability, etc. has become a current research hotspot.

[0003] To overcome the flexibility and bandwidth limitations of metamaterials, researchers combine nanometer / micrometer-sized wave-absorbing agents (such as MXene, graphene, carbon nanotubes, magnetic nanoparticles) with traditional textile fibers to prepare wave-absorbing fabrics through spinning, coating, electrospinning, etc. The wave-absorbing fabric uses a fiber fabric as a matrix and realizes impedance matching and multiple scattering loss through a multi-layer or composite structure. However, most researches focus on the X-band (8-12 GHz) or millimeter wave band (30-100 GHz), and there is limited data on absorption efficiency and bandwidth in the terahertz frequency band; single-layer coatings are prone to peeling off, and multi-layer structures mainly use iron-based or stainless steel fibers, which have poor conductivity and magnetic loss characteristics; it is difficult to achieve continuous broadband and high-depth absorption in the high-frequency terahertz band while considering lightness and flexibility. In summary, the existing metamaterial wave-absorbing devices cannot simultaneously achieve wide bandwidth, flexibility and low-cost preparation, and the performance of wave-absorbing fabrics in the terahertz frequency band is still not perfect. SUMMARY

[0004] The main purpose of the present application is to provide a terahertz wave-absorbing fabric and a preparation method thereof, which aims to solve the problem that the performance of wave-absorbing fabrics in the terahertz frequency band is not perfect.

[0005] To achieve the above-mentioned purpose, the present application provides a terahertz wave-absorbing fabric, which comprises:

[0006] a conductive fiber porous array layer;

[0007] an intermediate medium layer arranged on one side of the conductive fiber porous array layer; and

[0008] a dense conductive cloth layer arranged on the side of the intermediate medium layer away from the conductive fiber porous array layer, forming a three-layer composite wave-absorbing structure.

[0009] In an embodiment, the pore size of the conductive fiber porous array layer is 80-110 µm, and the fiber diameter is 30-50 µm.

[0010] In an embodiment, the intermediate medium layer has a thickness of 100 to 200 µm.

[0011] In an embodiment, the densely conductive cloth layer has a single fiber diameter of 8 to 12 µm, and a twisted fiber width of 120 to 180 µm;

[0012] The densely conductive cloth layer is woven by using a plain weave method.

[0013] In an embodiment, the densely conductive cloth layer and the intermediate medium layer are connected by sewing; and / or,

[0014] The intermediate medium layer and the conductive fiber porous array layer are connected by sewing.

[0015] In an embodiment, the conductive fiber porous array layer is made of any one of copper, nickel, aluminum, silver, carbon, and alloys thereof; and / or,

[0016] The intermediate medium layer is made of any one of silk, acetate, or polyester; and / or,

[0017] The densely conductive cloth layer is made of any one of copper, nickel, aluminum, silver, carbon, and alloys thereof.

[0018] The application also provides a preparation method of a terahertz wave absorbing fabric, for preparing the terahertz wave absorbing fabric described in any one of the above embodiments, comprising the following steps:

[0019] Obtaining a conductive cloth, an intermediate medium layer, and a conductive fiber porous array, respectively;

[0020] Fixing the intermediate medium layer to the conductive cloth, and fixing the conductive fiber porous array to the intermediate medium layer, to form a densely conductive cloth layer, an intermediate medium layer, and a conductive fiber porous array layer.

[0021] In an embodiment, the conductive fiber porous array is made of copper-nickel alloy conductive fiber.

[0022] The step of obtaining the conductive fiber porous array comprises:

[0023] High-purity oxygen-free copper wire is packaged into a bundle after acid washing by using a bundle drawing method, and the woven copper wire is drawn.

[0024] The woven copper wire is woven by using a plain weave method to obtain a copper cloth.

[0025] The copper cloth is soaked in sodium hydroxide, and the copper cloth is washed to neutral.

[0026] The copper cloth is electroplated by using an electroplating solution containing nickel sulfate to obtain a plated fiber cloth.

[0027] The post-plating fiber cloth is cleaned by deionized water, and chromium passivation is performed to obtain the copper-nickel fiber cloth, which forms the conductive fiber porous array.

[0028] In an embodiment, after the step of cleaning the post-plating fiber cloth by deionized water, and chromium passivation is performed to obtain the copper-nickel fiber cloth, which forms the conductive fiber porous array, the method further comprises: sequentially performing hydrogen removal heat treatment, crystallization optimization heat treatment and surface dip coating treatment on the conductive fiber porous array layer.

[0029] The present application provides a terahertz wave absorbing fabric, which comprises a conductive cloth layer, an intermediate medium layer arranged on one side of the dense conductive cloth layer, and a conductive fiber porous array layer arranged on the side of the intermediate medium layer away from the dense conductive cloth layer, forming a three-layer composite wave absorbing structure. Terahertz waves pass through the conductive conductive fiber porous array layer, the non-conductive intermediate medium layer and the dense conductive cloth layer in sequence to achieve wideband, high-efficiency and flexible wave absorption in the 0.1-2 THz wave band, meeting the application requirements of wearable, stealth protection and electromagnetic compatibility, etc. The absorption rate reaches 0.9 in 50% of the frequency band. The structure is clear and easy to prepare, and can be realized by using textile technology. The structure is simple and low in cost, and is suitable for mass production. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a structural image of the conductive fiber porous array layer provided by the embodiment scheme of the present application;

[0031] Figure 2 is a physical image of the terahertz wave absorbing fabric provided by the embodiment scheme of the present application;

[0032] Figure 3 is a microscopic image of the conductive cloth provided by the embodiment scheme of the present application;

[0033] Figure 4 is a structure simulation image of the terahertz wave absorbing fabric provided by the embodiment scheme of the present application;

[0034] Figure 5 is a wave absorbing test image of each part of the structure of the terahertz wave absorbing fabric provided by the embodiment scheme of the present application.

[0035] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0036] With reference to the drawings and the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0037] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, motion condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0038] In addition, if the embodiments of the present application involve descriptions of “first”, “second”, etc., the descriptions of “first”, “second”, etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first”, “second” can explicitly or implicitly include at least one of the features. In addition, the meaning of “and / or” appearing throughout the text includes three parallel solutions. Taking “A and / or B” as an example, it includes A solution, or B solution, or A and B solutions. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of a person of ordinary skill in the art, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope of the present application.

[0039] Please refer to Figure 1 , Figure 2 and Figure 3 , the present application provides a terahertz wave-absorbing fabric, comprising a dense conductive cloth layer, an intermediate medium layer and a conductive fiber porous array layer; the intermediate medium layer is arranged on one side of the conductive fiber porous array layer; the dense conductive cloth layer is arranged on the side of the intermediate medium layer away from the conductive fiber porous array layer, forming a three-layer composite wave-absorbing structure.

[0040] Please refer to Figures 4-5The application provides a terahertz wave absorbing fabric, which comprises a dense conductive cloth layer, an intermediate medium layer arranged on one side of the dense conductive cloth layer, and a conductive fiber porous array layer arranged on the side of the intermediate medium layer away from the dense conductive cloth layer, so as to form a three-layer composite wave absorbing structure. Terahertz waves pass through the conductive conductive fiber porous array layer, the non-conductive intermediate medium layer and the dense conductive cloth layer in sequence, so as to realize broadband, efficient and flexible wave absorption in the 0.1-2 THz wave band, meet the application requirements of wearable, stealth protection and electromagnetic compatibility, and the absorption rate reaches 0.9 in 50% of the frequency band. The structure is clear in hierarchy, easy to prepare, can be realized by using textile technology, simple in structure, low in cost and suitable for mass production.

[0041] In the embodiment provided by the application, the pore diameter of the conductive fiber porous array layer is 80-110 µm, and the fiber diameter is 30-50 µm.

[0042] The thickness of the intermediate medium layer is 100-120 µm.

[0043] The diameter of the single fiber of the dense conductive cloth layer is 8-12 µm, and the width of a cluster of fibers after twisting is 120-180 µm; the dense conductive cloth layer is woven by using plain weave method, so as to adapt to the wavelength of terahertz.

[0044] The fixing mode between the conductive cloth layer, the intermediate medium layer and the conductive fiber porous array layer is various, for example, adhesive fixing, and in the embodiment, the conductive cloth layer and the intermediate medium layer are connected by sewing.

[0045] Similarly, the intermediate medium layer and the conductive fiber porous array layer are connected by sewing.

[0046] The conductive fiber porous array layer is made of conductive material and has various implementation modes, and the material of the conductive fiber porous array layer comprises any one of copper, nickel, aluminum, silver, carbon and alloys thereof.

[0047] Specifically, in the embodiment, the conductive fiber porous array layer is a copper-nickel alloy conductive fiber.

[0048] In addition, the intermediate medium layer is made of non-conductive material and also has various implementation modes, and the intermediate medium layer comprises any one of silk, acetic acid or polyester high molecular fiber material, which is not limited here.

[0049] Similarly, the dense conductive cloth layer is made of conductive metal fiber, as long as it can conduct electricity, and the material of the dense conductive cloth layer comprises any one of copper, nickel, aluminum, silver, carbon and alloys thereof, which is not limited here.

[0050] Based on the above-mentioned terahertz wave absorbing fabric, the application further provides a preparation method of the terahertz wave absorbing fabric, which is used to prepare the terahertz wave absorbing fabric according to the above-mentioned method, and comprises the following steps:

[0051] S10, respectively acquiring the conductive cloth, the intermediate medium and the conductive fiber porous array;

[0052] S20, fixing the intermediate medium to the conductive cloth and fixing the conductive fiber porous array to the intermediate medium to form the conductive cloth layer, the intermediate medium layer and the conductive fiber porous array layer.

[0053] In the embodiment, the conductive fiber porous array comprises copper-nickel alloy conductive fiber;

[0054] The step of acquiring the conductive fiber porous array comprises:

[0055] S01, using the bundle drawing method to package high-purity oxygen-free copper wires into a bundle after acid washing, and drawing to obtain braided copper wires;

[0056] S02, using the plain weave method to weave the braided copper wires to obtain copper cloth;

[0057] S03, soaking the copper cloth in sodium hydroxide and washing the copper cloth to neutral;

[0058] S04, electroplating the copper cloth through an electroplating solution containing nickel sulfate to obtain plated fiber cloth;

[0059] S05, cleaning the plated fiber cloth through deionized water and performing chromium passivation to obtain the copper-nickel fiber cloth, and the copper-nickel fiber cloth forms the conductive fiber porous array.

[0060] Further, after step S05, it further comprises: sequentially performing hydrogen removal heat treatment, crystallization optimization heat treatment and surface immersion coating treatment on the conductive fiber porous array.

[0061] In the application, a specific embodiment is provided:

[0062] Using the bundle drawing method, 500-3000 high-purity oxygen-free copper wires (≥99.95%) with a diameter of 0.1-0.3 mm are packaged into a bundle after acid washing, and are drawn in multiple passes to finally obtain braided copper wires with a single wire diameter of 40-50 μm;

[0063] Using the plain weave method, the braided copper wires are woven to obtain copper cloth with a density of 300-400 roots / cm (fabric aperture 95-110 μm);

[0064] The copper cloth is soaked in 5% NaOH (containing 0.1% thiourea) at 50-60°C for 40 minutes;

[0065] The copper cloth is washed to neutral, pre-dried at 80°C for 1 hour, and then vacuum dried at 130°C for 1 hour, with a water content of ≤0.3%.

[0066] Pulse plating in a plating solution mainly containing NiSO4: current density 2-4 A / dm2, duty cycle 50%, temperature 50-60°C, pH 4-5 (adjusted by H2SO4), time 15-25 minutes; coating thickness 100-200 nm, porosity <5%;

[0067] After plating, the coating is cleaned with three-stage deionized water to remove residual liquid; 0.1% chromium acid passivation (60°C, 1 min)

[0068] Segmented heat treatment: hydrogen removal stage: 120°C, 10 minutes (N2 protection, flow ≥5 L / min); crystallization optimization: 250°C, 5 minutes (N2 protection), stress elimination and improvement of coating adhesion.

[0069] Surface protection: 0.5 μm water-based acrylic resin by dip coating.

[0070] In another aspect, the step of obtaining the conductive cloth comprises:

[0071] S001, soaking the carbon fiber precursor in an alkaline solution, and washing the carbon fiber precursor to neutral and drying;

[0072] S002, pre-oxidizing the carbon fiber precursor in an air atmosphere using a stepwise heating process while controlling the tension;

[0073] S003, sequentially performing low-temperature carbonization, high-temperature carbonization, and graphitization on the carbon fiber precursor to obtain a carbonized carbon fiber precursor;

[0074] S004, anodizing the carbonized carbon fiber precursor and coating an epoxy emulsion;

[0075] S005, weaving the carbonized carbon fiber precursor using a plain weave method to obtain the conductive cloth.

[0076] Wherein, the diameter of the single fiber in the conductive cloth is 8-12 µm, the conductive cloth is woven by a plain weave method, and the cluster width of the conductive cloth is 150-200 µm.

[0077] It should be noted that step S004 further comprises:

[0078] The PAN precursor is soaked in an alkaline solution (5% NaOH) at 80°C for 30 minutes, then washed to neutral, and dried at 110°C under vacuum conditions for 2 hours, with a water content controlled to be below 0.5%.

[0079] The pre-oxidation treatment is performed in an air atmosphere by a stepwise heating process (220℃ / 40min→240℃ / 40min→260℃ / 40min) with tension control (firstly stretched to 1.05 times of the original length, and then released to 0.98 times of the original length), so as to promote the cyclization and cross-linking reaction of PAN molecular chains, form a ladder structure, and increase the oxygen content to 8-10%.

[0080] The low-temperature carbonization is completed by heating to 800℃ at a rate of 5℃ / min and maintaining for 20 minutes under nitrogen protection; then the high-temperature carbonization is performed by heating to 1500℃ at a rate of 10℃ / min and maintaining for 10 minutes under argon atmosphere; finally, the graphitization treatment is performed at 2800℃ under argon protection for 3 minutes, so as to improve the crystallinity and conductivity.

[0081] The obtained carbon cloth is arranged in an ammonium nitrate (1mol / L) electrolyte for anodic oxidation treatment, the current density is 0.5A / dm², and the treatment time is 90 seconds, so as to improve the surface activity; then the surface is uniformly coated with 1.0wt% of an epoxy emulsion (particle size <200nm), and dried at 110℃, so as to enhance the interfacial bonding force with the resin matrix.

[0082] The plain weave method is performed by using a high-precision loom, and the cluster width is controlled to be 150-200µm.

[0083] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation according to the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A terahertz wave absorbing fabric, characterized by, The application relates to a three-layer composite wave-absorbing structure, which comprises the following parts: a conductive fiber porous array layer; an intermediate medium layer arranged on one side of the conductive fiber porous array layer; and a dense conductive cloth layer arranged on the side of the intermediate medium layer away from the conductive fiber porous array layer. The conductive fiber porous array layer is woven by using a plain weave method. The dense conductive cloth layer is woven by using a plain weave method. The pore diameter of the conductive fiber porous array layer is 80-110 mu m, and the fiber diameter is 30-50 mu m. The thickness of the intermediate medium layer is 100-200 mu m. The diameter of the single fiber of the dense conductive cloth layer is 8-12 mu m, and the width of the fiber cluster after twisting is 120-180 mu m. The dense conductive cloth layer and the intermediate medium layer are connected by sewing; and / or 2. The terahertz wave absorbing fabric according to claim 1, wherein, The intermediate medium layer and the conductive fiber porous array layer are connected by sewing.

3. The terahertz wave absorbing fabric according to claim 1, wherein, The material of the conductive fiber porous array layer comprises any one of copper, nickel, aluminum, silver, carbon and alloys thereof; and / or 4. The terahertz wave absorbing fabric according to claim 1, wherein, The intermediate medium layer comprises any one of silk, acetic acid or polyester; and / or 5. The terahertz wave absorbing fabric according to claim 1, wherein, The material of the dense conductive cloth layer comprises any one of copper, nickel, aluminum, silver, carbon and alloys thereof. The application further relates to a method for manufacturing the three-layer composite wave-absorbing structure, which comprises the following steps: obtaining a conductive cloth, an intermediate medium and a conductive fiber porous array respectively; fixing the intermediate medium on the conductive cloth and fixing the conductive fiber porous array on the intermediate medium to form a dense conductive cloth layer, an intermediate medium layer and a conductive fiber porous array layer.

6. The terahertz wave absorbing fabric according to claim 1, wherein, The conductive fiber porous array comprises copper-nickel alloy conductive fibers. The step of obtaining the conductive fiber porous array comprises the following steps: packaging high-purity oxygen-free copper wires into a bundle after acid washing by using a bundle drawing method to draw and obtain woven copper wires; weaving the woven copper wires by using a plain weave method to obtain a copper cloth; soaking the copper cloth in sodium hydroxide and washing the copper cloth to be neutral; electroplating the copper cloth by using an electroplating solution containing nickel sulfate to obtain plated fiber cloth; cleaning the plated fiber cloth by using deionized water and performing chromic acid passivation to obtain copper-nickel fiber cloth, which forms the conductive fiber porous array. After the step of cleaning the plated fiber cloth by using deionized water and performing chromic acid passivation to obtain the copper-nickel fiber cloth, which forms the conductive fiber porous array, the method further comprises the following steps: sequentially performing hydrogen removal heat treatment, crystallization optimization heat treatment and surface immersion coating treatment on the conductive fiber porous array.

7. A method for preparing a terahertz wave absorbing fabric according to any one of claims 1 to 6, characterized in that, ​ ​ ​ 8. The method for preparing terahertz absorbing fabric according to claim 7, characterized in that, ​ ​ ​ ​ ​ ​ ​ 9. The method of claim 8, wherein the fabric is a woven fabric. ​

Images