Radiation absorbing material, preparation method and application in three-dimensional configuration

Abstract

The invention relates to the technical field of material processing, in particular to a radiation absorbing material, a preparation method and application in a three-dimensional configuration. The radiation absorption material comprises conductive carbon black ECB powder and thermoplastic polyurethane (TPU) particles which are mixed and then extruded into filaments, the average diameter of the ECB powder ranges from 11 nm to 15 nm, and the mass ratio of the ECB powder to the TPU particles is 2.5-4: 17. The radiation absorption material has good electromagnetic radiation absorption and energy absorption, the formed wires can be conveniently printed into complex shapes, and the radiation absorption material has a good effect on radiation protection of parts on automobiles and has great popularization value.

Description

Technical Field

[0001] The present invention relates to the technical field of material processing, and particularly to a radiation absorption material, a preparation method thereof, and an application in a three-dimensional configuration. Background Art

[0002] With the development of the electrification, intelligence, and networking of automobiles, the high-frequency electromagnetic radiation signals increase, and the electromagnetic compatibility faces a severe test. Generally, electromagnetic waves are mainly converted into heat energy through magnetic loss and dielectric loss to achieve the effect of energy conversion and absorption, and effectively achieve the effects of electromagnetic protection and radar wave stealth. Common wave-absorbing materials include ferrite coatings, dielectric wave-absorbing layers, etc. Among them, dielectric wave absorption mainly realizes the introduction and absorption of electromagnetic waves through matching design. Since the dielectric wave-absorbing layer generally has a multi-layer structure, the manufacturing process is relatively complex.

[0003] To solve the above technical problems, the development of metamaterials with electromagnetic wave absorption functions has attracted more and more attention. Metamaterials refer to artificial composite structures or composite materials with extraordinary properties that natural materials do not possess, providing a brand-new idea for the field of material design. In terms of electromagnetic wave absorption, metamaterials complete the absorption of electromagnetic waves by controlling the key physical dimensions of functional materials, constructing electromagnetic resonance structures, and coupling with the electromagnetic components of incident electromagnetic waves. The electromagnetic wave absorption metamaterials have the advantages of small sample thickness, strong absorption effect, wide selection range of materials, and the absorption frequency band can be freely designed.

[0004] Since the manufacturing difficulty of metamaterials lies in the construction of large-scale microstructures and the control of structural accuracy, and generally needs to be processed by microfabrication technologies such as photolithography and electron beam lithography, the manufacturing method is complex, the manufacturing cycle is long, and the cost is high.

[0005] Therefore, it is necessary to develop a radiation absorption material and a preparation method thereof, and the radiation absorption material can obtain an electromagnetic shielding structure through 3D printing to realize the application in a three-dimensional configuration. Summary of the Invention

[0006] The object of the present invention is to solve the deficiencies of the above background art, and provide a radiation absorption material, a preparation method thereof, and an application in a three-dimensional configuration. The radiation absorption material can obtain an electromagnetic shielding structure through 3D printing, and efficiently absorb various functional electromagnetic radiations on automobiles.

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

[0008] A radiation absorption material, comprising electrically conductive carbon black ECB powder and thermoplastic polyurethane TPU particles that are mixed and extruded into filaments. The average diameter of the ECB powder is 11-15 nm, and the mass ratio of the ECB powder to the TPU particles is 2.5-4:17.

[0009] Preferably, the average diameter of the ECB powder is 13 nm, and the mass ratio of the ECB powder to the TPU particles is 3:17.

[0010] According to a radiation absorption material provided by the present application, the diameter of the wire obtained by extrusion into a wire is 1.75 mm, 2.85 mm or 3.00 mm.

[0011] The present application also relates to a preparation method of a radiation absorption material, including: drying and stirring and mixing the electrically conductive carbon black ECB powder and the thermoplastic polyurethane TPU particles, and then extruding into a wire by a twin-screw extruder to obtain a radiation absorption material wire that can be used for 3D printing.

[0012] According to a preparation method of a radiation absorption material provided by the present application, the drying includes: treating in an oven at 75-80 °C for 11.5-12.5 h.

[0013] According to a preparation method of a radiation absorption material provided by the present application, the stirring and mixing includes: uniformly dispersing in a planetary mixer at a rotation speed of 25-30 r / min for 60-65 min.

[0014] The present application also relates to an application of a radiation absorption material in a three-dimensional configuration, including: designing electromagnetic units CS1 and CS2 based on the radiation absorption material, and the design method includes: both electromagnetic units CS1 and CS2 are array-like block structures composed of n×n sub-blocks, and the length and width of each sub-block in each electromagnetic unit are the same, but the thicknesses are different. The thicknesses of each sub-block in electromagnetic units CS1 and CS2 and the usage ratio of CS1 and CS2 are determined with the optimization of the reflectivity of the electromagnetic shielding structure as the goal, and the arrangement positions of CS1 and CS2 in the electromagnetic shielding structure are designed according to the usage ratio;

[0015] Taking the filamentous radiation absorption material as the raw material for 3D printing, the electromagnetic shielding structure is printed according to the corresponding sub-block thicknesses and arrangement positions of the determined electromagnetic units CS1 and CS2.

[0016] According to an application of a radiation absorption material in a three-dimensional configuration provided by the present application, in each electromagnetic unit, the bottom surfaces of all sub-blocks are flush and are fused together along the width direction and the length direction.

[0017] According to an application of a radiation absorption material in a three-dimensional configuration provided by the present application, 3D printing is carried out by using a dual-nozzle 3D printer. One nozzle is used to print electromagnetic units CS1 and CS2, and the other nozzle is used to print a support material on the top in the sub-block thickness direction; the support material is a material that can be dissolved after the electromagnetic shielding structure is printed.

[0018] According to an application of a radiation absorption material in a three-dimensional configuration provided by the present application, the support material is a polyvinyl alcohol wire.

[0019] Application of a radiation absorption material in a three-dimensional configuration according to the present application. In the design method: both the electromagnetic units CS1 and CS2 are arranged in a 2×2 array to form their respective supercells. The thickness of each sub-block in the electromagnetic units CS1 and CS2 and the proportion of the amount used between the supercells of the electromagnetic units CS1 and CS2 are determined with the goal of optimizing the reflectivity of the electromagnetic shielding structure. The arrangement positions of the supercells of the electromagnetic units CS1 and CS2 in the electromagnetic shielding structure are designed according to the proportion of the amount of the supercells.

[0020] The advantages of the present application are as follows: 1. The radiation absorption material of the present application is very simple to prepare. Conductive carbon black can effectively absorb electromagnetic radiation, and thermoplastic polyurethane can quickly bond the conductive carbon black to form the required filamentous material, which is convenient for subsequent rapid printing based on a 3D printer to form a component shell with a complex thickness.

[0021] 2. The size of the filament in the present application is optimized. The filament of this diameter can be well used for 3D printing, meeting the requirements of mainstream 3D printing on the market currently, and is extremely convenient to apply, and the formed structure is also more delicate.

[0022] 3. The present application also relates to a preparation method. The method for preparing the radiation absorption material filament in the present application is very simple, and very few equipment tools are used, which is suitable for large-scale production, and the manufacturing cost is also extremely low.

[0023] 4. The treatment method for the filament in the present application is very convenient. It can be processed in an oven at 75 - 80 °C for 11.5 - 12.5 h, and the operation is simple.

[0024] 5. The stirring treatment method for the filament in the present application is simple. It can be evenly dispersed in a planetary stirrer at a set rotation speed.

[0025] 6. The present application also relates to the preparation of an electromagnetic shielding structure. The preparation method in the present application is realized by 3D printing. The constructed electromagnetic unit is formed by multiple sub-blocks, with a fine structure, excellent electromagnetic radiation absorption effect, and simple preparation.

[0026] 7. The electromagnetic unit in the present application is a plate-like structure with an uneven surface arranged in a matrix array of multiple sub-blocks, with a delicate structure and excellent electromagnetic radiation absorption effect.

[0027] 8. By using a dual-nozzle printer for printing in the present application, the uneven surface structure required in the present application can be constructed through support materials that can be eliminated. The support materials effectively support the sub-blocks during the printing process and can be eliminated by dissolution after printing, forming a precise surface. The constructed structure has a good anti-electromagnetic radiation effect.

[0028] 9. The support material of the present application is simple and easy to obtain, with low cost and convenient for printing, reducing the cost of constructing complex and precise surface structures;

[0029] 10. The three-dimensional configuration of the present application has a simple structure, which is a regular structure and is convenient for design, calculation and printing.

[0030] The electromagnetic radiation absorption material of the present application has good electromagnetic radiation absorption and energy absorption. The formed wire can conveniently print complex shapes and has a good effect on preventing radiation of components on automobiles, with great popularization value. Description of the Drawings

[0031] Figure 1 are the microscopic morphology diagrams of pure TPU material and ECB / TPU composite material;

[0032] Figure 2 is the dielectric loss characteristic diagram of ECB / TPU composite material;

[0033] Figure 3 is the reflectivity diagram of flat ECB / TPU composite material with different thicknesses;

[0034] Figure 4 are the sub-block thickness data of CS1 and CS2 block units in Example 2;

[0035] Figure 5 is the schematic diagram of electromagnetic unit formed by 4 block units in Example 2 (plan view);

[0036] Figure 6 is the schematic diagram of electromagnetic unit formed by multiple sub-blocks in Example 2 (side view);

[0037] Figure 7 is the schematic diagram of the arrangement mode of electromagnetic units CS1 and CS2 in Example 2 (plan view);

[0038] Figure 8 is the phase of electromagnetic units CS1 and CS2 in the electromagnetic shielding structure of Example 2;

[0039] Figure 9 is the physical sample of the electromagnetic shielding structure in Example 2;

[0040] Figure 10 is the reflectivity of the superstructure of the electromagnetic shielding structure in Example 2 under the incidence of TE polarization and TM polarization waves from 1 GHz to 4 GHz;

[0041] Figure 11 is the reflectivity of the superstructure of the electromagnetic shielding structure in Example 2 under the incidence of TE polarization and TM polarization waves from 4 GHz to 18 GHz. Detailed Embodiments

[0042] Embodiments of the present application will be described in detail below, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, but should not be construed as limiting the present application.

[0043] In the description of the present application, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present application.

[0044] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0045] The following specific embodiments further illustrate the present invention in detail.

[0046] Embodiment 1

[0047] The present application relates to a radiation-absorbing material, a preparation method of the radiation-absorbing material, and an application of the radiation-absorbing material. The application of the radiation-absorbing material in the present application is to form the prepared radiation-absorbing material into filaments, and then use a 3D printer to print it into a required complex structure to adapt to the complex outer shape of automotive parts. The formed structure not only has good electromagnetic radiation absorption performance but also can perfectly fit the structural surface of complex parts.

[0048] Currently, commonly used 3D polymer materials such as ABS, PLA, PC, PVA, nylon, etc. are wave-transparent materials and have good electromagnetic wave permeability. By adding conductive materials such as ultrafine carbon powder, nano-metal powder, carbon nanotubes, and graphene, the electrical properties of polymer materials can be changed to make them have dielectric wave absorption and magnetic wave absorption properties. In terms of the structural design of metamaterials, by constructing various three-dimensional microstructures that meet the electromagnetic wave absorption requirements, the metamaterials can achieve the best impedance matching in the working frequency band. Through the dielectric loss or / and Ohmic loss in the wave-absorbing metamaterials, the electromagnetic waves incident on the material interior are converted into heat energy or other energies to achieve the absorption of electromagnetic waves. Since 3D printing can realize the manufacturing of structures from the nanoscale to the meter scale, 3D printing technology can provide a new way for the low-cost processing and manufacturing of broadband wave-absorbing metamaterials.

[0049] In this application, the prepared radiation absorption material is formed into the required parts housing by 3D printing. The radiation absorption material of this application includes electrically conductive carbon black (ECB) powder and thermoplastic polyurethane (TPU) particles that are mixed and extruded into filaments. The average diameter range of the ECB powder is 11 - 15 nm, and the mass ratio of the ECB powder to the TPU particles is 2.5 - 4:17. Among them, the diameter specifications of the filaments obtained by extrusion are one of 1.75 mm, 2.85 mm, and 3.00 mm, and the above three diameters are the commonly used 3D printing filament diameters.

[0050] In this embodiment, the raw material uses electrically conductive carbon black (ECB) with an average diameter of 13 nm as the absorber of the composite material, and uses 95A thermoplastic polyurethane (TPU) as the matrix of the composite material.

[0051] The specific steps for preparing the ECB / TPU composite material filaments are as follows:

[0052] First, dry the ECB powder and TPU particles in an oven at 80 °C for 12 h; then, mix the ECB powder and TPU particles in a planetary mixer at a mass ratio of 3:17 and stir evenly at a speed of 30 r / min for 1 h;

[0053] Finally, under the action of heat melting and screw friction shearing, inject the uniform mixture into a twin-screw extruder (Nanjing Giant Machinery Co., Ltd., Shj-20) to extrude composite material filaments with a diameter specification of 2.85 mm.

[0054] This composite material has good plasticity and can be applied to the 3D printing process to prepare a more refined material structure. Use a scanning electron microscope (Tescan Co., Ltd., VEGA3SBU) to observe the microstructure of the ECB / TPU composite material. As Figure 1As shown, the surface of the pure TPU matrix without ECB in the left figure is smooth (comparative material), and the ECB particles in the ECB / TPU composite material in the right figure are evenly dispersed in the matrix with less agglomeration, indicating that the prepared composite material has good uniformity.

[0055] Using a vector network analyzer (Agilent Technologies Co., Ltd., Ceyear AV3672D), the dielectric constant and magnetic permeability of the material in the frequency band of 1 - 18 GHz were measured by the coaxial transmission line method. As Figure 2 shown, the test results show that the composite material has dielectric loss characteristics. On this basis, the reflectivity of the flat ECB / TPU composite material with different thicknesses was simulated, as Figure 3 shown. When the thickness is 5 mm, the reflectivity has a minimum value of -7.8 dB, and when the thickness is 10 - 30 mm, the reflectivity basically remains unchanged. It can be seen that the reflectivity of the flat composite material with a thickness of 5 - 30 mm and a frequency band of 2 - 18 GHz is greater than -10 dB. The results show that there are limitations in the design of the flat materials with the above thickness, and their narrow-band and low-efficiency absorption characteristics are caused by the impedance mismatch of the flat materials with the same thickness, and further structural optimization design should be carried out.

[0056] Example 2

[0057] In some embodiments of the present application, this embodiment provides an application of a radiation absorption material in a three-dimensional configuration. Specifically, in this embodiment, the required superstructure is printed by a 3D printer (Weibao Technology Co., Ltd., Ultimaker S3) through the fused deposition modeling (FDM) technology to form the required electromagnetic shielding structure. The printer has a dual nozzle, one nozzle is used to print the radiation absorption material, and the other nozzle is used to print the support material.

[0058] By preparing the above-mentioned radiation absorption material into filaments and then using a 3D printer for printing, the 3D printer prints out sub-blocks, and the sub-blocks are combined to form electromagnetic units CS1 and CS2. The electromagnetic units CS1 and CS2 are combined according to a set ratio and arrangement method to form the required structural form. The sub-block is a cuboid structure, and the sub-blocks are arranged in an array pattern to form electromagnetic units.

[0059] The design method of the electromagnetic units CS1 and CS2 includes: both the electromagnetic units CS1 and CS2 are array-like block structures composed of n×n sub-blocks. The length and width of each sub-block in each electromagnetic unit are the same, but the thickness is different. The thickness of each sub-block in the electromagnetic units CS1 and CS2 and the proportion of the usage of CS1 and CS2 are determined with the goal of optimizing the reflectivity of the electromagnetic shielding structure, and the arrangement positions of CS1 and CS2 in the electromagnetic shielding structure are designed according to the proportion of the usage.

[0060] In the design method of some preferred examples, the electromagnetic units CS1 and CS2 can be arranged in a 2×2 array to form their respective supercells. With the goal of optimizing (minimizing) the reflectivity of the electromagnetic shielding structure, the thickness of each sub-block in the electromagnetic units CS1 and CS2 and the proportion of the amount used between the supercells of the electromagnetic units CS1 and CS2 are determined. According to the proportion of the amount used in the supercells, the arrangement positions of the supercells of the electromagnetic units CS1 and CS2 in the electromagnetic shielding structure are designed. Setting the electromagnetic units as supercells can reduce the in-plane coupling and meet the periodic boundary conditions of the simulation.

[0061] In this embodiment, both the electromagnetic units CS1 and CS2 are matrix-like block structures composed of 10×10 (n = 10) sub-blocks. The value of n can be set by itself, but when n is too large, the length and width of the sub-blocks are small. Therefore, the reasonable setting of n can be referred to the existing printing accuracy. The electromagnetic unit is a block structure formed by symmetrically arranging four block units of m×m sub-blocks. As Figure 4 shown, the block units of CS1 and CS2 are 5×5 (m = 5) sub-blocks, and the numbers on each sub-block represent the thickness. The sub-blocks without marked numbers indicate that their thicknesses are symmetrically arranged along the diagonal of the block unit. The four block units are arranged in a symmetric manner according to the thickness of the sub-blocks, that is, the thickness of all sub-blocks of the electromagnetic unit is obtained. Specifically, as Figure 5 shown, the x-direction represents the length direction of the sub-block, and the y-direction represents the width direction of the sub-block. Taking Figure 5 the upper-right block unit as a reference (that is, the block unit shown in Figure 4 ), first obtain the whole on the right by symmetry along the x-axis, and then by symmetry along the y-axis, to obtain the complete CS1 and CS2.

[0062] In this embodiment, the length and width of the sub-blocks in each electromagnetic unit are equal. As Figure 6 shown, the length direction described in this embodiment is the direction perpendicular to the paper surface in Figure 6 , the width direction described in this embodiment is the left-right direction in Figure 6 , and the thickness direction described in this embodiment is the up-down direction in Figure 6 . The thicknesses of the sub-blocks in the same electromagnetic unit are not consistent, that is, they include sub-blocks of multiple thicknesses. These sub-blocks are arranged in an array according to a set manner, and finally the required electromagnetic unit is formed. The two electromagnetic units are combined in a set manner to form the required electromagnetic shielding structure. Of course, it can also be a combination of multiple electromagnetic units, but because there are more complex phases, only the electromagnetic shielding structure formed by the combination of two electromagnetic units is discussed in this embodiment.

[0063] The 3D-printed electromagnetic shielding structure in this embodiment is composed of two electromagnetic units CS1 and CS2 combined, as Figure 7 shown. Figure 7The medium blue block represents the super unit of electromagnetic unit CS1, and the gray block represents the super unit of CS2. The difference between electromagnetic units CS1 and CS2 is that the thickness of their internal sub-blocks is different. The thickness of the sub-blocks of each electromagnetic unit and the proportion of each electromagnetic unit are calculated. Electromagnetic units CS1 and CS2 are prepared based on radiation absorbing materials. The thickness of each sub-block in the CS1 and CS2 matrices and the proportion of CS1 super units and CS2 super units in the electromagnetic shielding structure are determined with the goal of optimizing the reflectivity of the electromagnetic shielding structure. The arrangement positions of CS1 super units and CS2 super units in the electromagnetic shielding structure are designed according to the proportion of super units. Figure 7 The ratio of CS1 super unit: CS2 super unit is 3:7. When designing the arrangement position, it is only necessary to first determine the position of one electromagnetic unit (CS1 or CS2) according to the usage ratio, and the remaining position is the position of the other electromagnetic unit (CS2 or CS1).

[0064] The thickness range of the sub-blocks is obtained through data analysis. Figure 3 It can be seen that the flat plate structure has structural limitations, so it is necessary to construct its three-dimensional structure for electromagnetic radiation absorption. However, the above test proves that when the radiation absorption material is at a thickness of 10 to 30 mm, the reflectivity remains basically unchanged, so the thickness benchmark of the sub-block can be set to 30 mm. The thickness of other sub-blocks in the electromagnetic unit is determined based on the 30 mm sub-block thickness.

[0065] This step can be determined by combining genetic algorithm with simulation analysis. At this point, the thickness and arrangement of each sub-block in the electromagnetic unit can be obtained. The required electromagnetic unit is formed. Figure 4 The electromagnetic unit shown has a thickness of 30mm in the middle sub-block, and the thickness of other surrounding sub-blocks is obtained by genetic algorithm combined with simulation analysis. The electromagnetic unit obtained by the above arrangement mode is a 10×10 structure, the length and width of the sub-block are both 1.5mm, the plane size of the electromagnetic unit is 15mm×15mm, and four electromagnetic units are arranged in a 2×2 matrix to form a super unit, and the array area of ​​the super unit is 30×30mm 2 Each sub-block occupies a space of 1.5mm×1.5mm. The bottom surface of each electromagnetic unit sub-block is flush in the thickness direction. Adjacent sub-blocks are welded together in the length and width directions. Finally, all electromagnetic units together form a plate-like structure (electromagnetic shielding structure) with a flat bottom surface and an uneven upper surface.

[0066] The electromagnetic units CS1 and CS2 of the above structure are simulated and analyzed, and it is found that the reflection phases of the electromagnetic units CS1 and CS2 have a stable phase difference in a wide frequency range, such as Figure 8As shown, effective electromagnetic deflection can be achieved. This design method avoids the problem of the complexity of the vehicle's electromagnetic environment caused by the oscillation of multi-directional signals during transmission in space through the concentrated deflection of electromagnetic radiation. At the same time, compared with flat materials of the same thickness, the electromagnetic shielding performance is further improved.

[0067] Using filamentous radiation-absorbing material as the raw material for 3D printing, print the electromagnetic shielding structure according to the corresponding sub-block thicknesses and arrangement positions of the determined electromagnetic units CS1 and CS2.

[0068] In order to form such an electromagnetic shielding structure with an uneven surface, during the 3D printer printing process, a dual-nozzle structure is adopted. One nozzle prints the electromagnetic unit, that is, the filamentous material of the above-mentioned radiation-absorbing structure is connected to print the electromagnetic unit, and the other nozzle prints the support material. During the process of printing the sub-blocks, the thickness of some sub-blocks is relatively large. If directly printed all at once, the sub-block may collapse. To avoid such situations, during the process of printing the sub-blocks, support material will be printed on the top of adjacent sub-blocks with a smaller thickness. For example, when the 3D printer prints a row of sub-blocks in the width direction, the sub-block with the smallest thickness in this row is 4.2 mm. The 3D printer can first use the radiation-absorbing structure nozzle to print a 4.2-mm bottom layer, and this bottom layer contains the lowest layer parts of all the sub-blocks in this row. Then, the second layer on the bottom is printed. Since the part corresponding to the 4.2-mm sub-block has been printed, when printing to this sub-block, a layer of support material is printed at the bottom of this sub-block through the support material nozzle, and radiation-absorbing material is printed at other positions, finally forming a second layer with the same height; and so on, until the sub-block with the largest thickness is also printed. After all the sub-blocks and the support material are printed, the upper surface of the formed structure is flat at this time, and then the support structure is removed, finally forming an electromagnetic shielding structure with an uneven surface.

[0069] In this embodiment, polyvinyl alcohol (PVA) filaments are selected as the support material. Since PVA has good water solubility, soak the sample in water for 6 h to dissolve the support material; then put it in an oven and dry it at 65 °C for 12 h to obtain a superstructure sample with an area of 300×300 mm 2 and an overall thickness of 30 mm (the overall thickness is calculated according to the maximum thickness). This process plan is integrally formed and is suitable for complex shape processes, and can be applied to the preparation of electromagnetic shielding structures.

[0070] After printing to form a stable structure according to the above method, then dissolve and eliminate the support structure on the top of the sub-blocks. Finally, the required electromagnetic shielding structure with a complex outer shape is formed, as Figure 9 shown.

[0071] Finally, a physical analysis of the electromagnetic shielding structure was carried out. The prepared sample was placed flat on the bracket for testing. The reflectance under the incidence of TE-polarized wave and TM-polarized wave is as follows Figures 10 - 11 shown. This electromagnetic shielding structure has polarization insensitivity and excellent low-reflection characteristics: the reflectance is less than -5 dB in the frequency band of 1 GHz to 2.4 GHz, less than -10 dB in the frequency band of 2.4 GHz to 5.8 GHz, less than -20 dB in the frequency band of 5.8 GHz to 7.8 GHz, and less than -30 dB in the frequency band of 7.8 GHz to 18 GHz. The test results show that this electromagnetic shielding structure exhibits high-efficiency radiation absorption characteristics in a wide frequency range. This technology verifies the refined material preparation and structural process scheme, and is expected to be applied in the field of electromagnetic shielding technology.

[0072] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present application. Without departing from the spirit and scope of the present application, the present application will have various changes and improvements, and these changes and improvements all fall within the scope of the present application claimed. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A radiation absorption material, characterized in that, It includes electrically conductive carbon black ECB powder and thermoplastic polyurethane TPU particles that are extruded into filaments after mixing. The average diameter range of the ECB powder is 11-15 nm, and the mass ratio of the ECB powder to the TPU particles is 2.5-4:

17.

2. The radiation absorption material according to claim 1, wherein The diameter specifications of the filaments obtained by extrusion are 1.75 mm, 2.85 mm, or 3.00 mm.

3. A method for preparing the radiation absorbing material as described in claim 1 or 2, characterized in that, It includes: The electrically conductive carbon black ECB powder and thermoplastic polyurethane TPU particles are dried and then stirred and mixed, and then extruded into filaments by a twin-screw extruder to obtain a radiation-absorbing material filament for 3D printing.

4. The preparation method of the radiation absorption material according to claim 3, characterized in that, The drying includes: treating in an oven at 75-80 °C for 11.5-12.5 h.

5. The preparation method of the radiation absorption material according to claim 3, characterized in that, The stirring and mixing includes: evenly dispersing in a planetary mixer at a rotation speed of 25-30 r / min for 60-65 min.

6. Use of a radiation absorbing material as described in claim 1 or 2 in a three-dimensional configuration, characterized in that, It includes: Based on the radiation-absorbing material, electromagnetic units CS1 and CS2 are designed. The design method includes: both electromagnetic units CS1 and CS2 are array-like block structures composed of n×n sub-blocks. The length and width of each sub-block in each electromagnetic unit are the same, but the thickness is different. The thickness of each sub-block in electromagnetic units CS1 and CS2 and the usage ratio of CS1 and CS2 are determined with the goal of optimizing the reflectivity of the electromagnetic shielding structure. The arrangement positions of CS1 and CS2 in the electromagnetic shielding structure are designed according to the usage ratio. Using the filamentous radiation-absorbing material as the raw material for 3D printing, an electromagnetic shielding structure is printed according to the corresponding sub-block thickness and arrangement position of the determined electromagnetic units CS1 and CS2.

7. Use of the radiation absorbing material according to claim 6 in a three-dimensional configuration, characterized in that, In each electromagnetic unit, the bottom surfaces of all sub-blocks are flush and are welded together along the width direction and the length direction.

8. Use of the radiation-absorbing material according to claim 7 in a three-dimensional configuration, characterized in that, A dual-nozzle 3D printer is used for 3D printing. One nozzle is used to print electromagnetic units CS1 and CS2, and the other nozzle is used to print a support material on the top in the thickness direction of the sub-blocks; the support material is a material that can be dissolved after the electromagnetic shielding structure is printed.

9. Use of the radiation absorbing material according to claim 8 in a three-dimensional configuration, characterized in that, The support material is a polyvinyl alcohol filament.

10. The application of the radiation absorbing material according to claim 6 in a three-dimensional configuration, characterized in that, In the design method: both electromagnetic units CS1 and CS2 are arranged in a 2×2 array to form their respective super-units. The thickness of each sub-block in electromagnetic units CS1 and CS2 and the usage ratio between the super-units of electromagnetic units CS1 and CS2 are determined with the goal of optimizing the reflectivity of the electromagnetic shielding structure. The arrangement positions of the super-units of electromagnetic units CS1 and CS2 in the electromagnetic shielding structure are designed according to the super-unit usage ratio.

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