CN117245758B - Preparation method and component of impedance gradient water-absorbent resin reinforced electromagnetic wave-absorbing concrete - Google Patents
Preparation method and component of impedance gradient water-absorbent resin reinforced electromagnetic wave-absorbing concrete Download PDFInfo
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- CN117245758B CN117245758B CN202310863304.XA CN202310863304A CN117245758B CN 117245758 B CN117245758 B CN 117245758B CN 202310863304 A CN202310863304 A CN 202310863304A CN 117245758 B CN117245758 B CN 117245758B
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- 229920005989 resin Polymers 0.000 title claims abstract description 107
- 239000011347 resin Substances 0.000 title claims abstract description 107
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- 239000002250 absorbent Substances 0.000 title claims abstract description 71
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- 239000010410 layer Substances 0.000 claims abstract description 65
- 239000002002 slurry Substances 0.000 claims abstract description 45
- 238000007639 printing Methods 0.000 claims abstract description 37
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 45
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- 230000008569 process Effects 0.000 claims description 8
- 239000006004 Quartz sand Substances 0.000 claims description 7
- 239000002562 thickening agent Substances 0.000 claims description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 6
- 239000010949 copper Substances 0.000 claims description 6
- 239000002893 slag Substances 0.000 claims description 6
- 239000011398 Portland cement Substances 0.000 claims description 5
- 229910021487 silica fume Inorganic materials 0.000 claims description 5
- 238000001125 extrusion Methods 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- WPJGWJITSIEFRP-UHFFFAOYSA-N 1,3,5-triazine-2,4,6-triamine;hydrate Chemical group O.NC1=NC(N)=NC(N)=N1 WPJGWJITSIEFRP-UHFFFAOYSA-N 0.000 claims description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims description 2
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/001—Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y70/00—Materials specially adapted for additive manufacturing
- B33Y70/10—Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00034—Physico-chemical characteristics of the mixtures
- C04B2111/00181—Mixtures specially adapted for three-dimensional printing (3DP), stereo-lithography or prototyping
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00241—Physical properties of the materials not provided for elsewhere in C04B2111/00
- C04B2111/00258—Electromagnetic wave absorbing or shielding materials
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Mechanical Engineering (AREA)
- Organic Chemistry (AREA)
- Civil Engineering (AREA)
- Composite Materials (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Abstract
The invention relates to a preparation method and a component of impedance gradient water-absorbent resin reinforced electromagnetic wave-absorbing concrete, comprising the following steps of; determining the mass of each layer of electromagnetic wave-absorbing concrete slurry during 3D printing, and determining the mass of the dried water-absorbing resin added with equivalent volume doping amount in each layer according to the mass of each layer of electromagnetic wave-absorbing concrete slurry; the equivalent volume doping amount of each layer is different from bottom to top, and the gradient increment is formed; when printing, after printing a layer of electromagnetic wave-absorbing concrete slurry, arranging an impedance gradient control device right above the electromagnetic wave-absorbing concrete slurry, and then throwing the dried water-absorbing resin with determined mass on the impedance gradient control device, so that the water-absorbing resin is uniformly distributed on the surface layer of the printed electromagnetic wave-absorbing concrete slurry in an array manner. The concrete has the advantages of higher reliability, wider impedance distribution range and the like, can control fixed wavelength and wave-absorbing frequency bands, can realize mass production of consistent components, and improves production efficiency.
Description
Technical Field
The invention relates to the technical field of 3D printing electromagnetic wave-absorbing concrete, in particular to a preparation method and a component of impedance gradient water-absorbing resin reinforced electromagnetic wave-absorbing concrete.
Background
With the rapid development of technology, electronic products are widely applied in the fields of national defense, medical treatment, military, civil use and the like. However, this rapid development also brings about serious problems of electromagnetic interference and radiation pollution. Therefore, prevention of electromagnetic interference and solving of problems such as radiation pollution have been attracting attention, and more scholars have started to put into research on electromagnetic wave absorbing materials.
An electromagnetic wave absorbing material is a material that dissipates electromagnetic wave energy into the interior of the material in the form of thermal energy or other forms. The conventional wave-absorbing material has some disadvantages in terms of absorption band and absorption performance, such as narrow absorption band, weak absorption performance, and the like. In practical engineering application, "thin, light, wide and strong" becomes a difficulty in technological breakthrough. In order to solve the problems, researchers optimize impedance matching of the wave absorbing material and realize efficient attenuation of electromagnetic waves through reasonable structural design and component regulation. Therefore, how to combine the impedance matching and attenuation capability of the material becomes the key of the current research of the wave-absorbing material.
The invention utilizes a 3D printing technology to apply the water-absorbent resin in the electromagnetic wave-absorbing concrete, provides a brand-new preparation method of the water-absorbent resin reinforced electromagnetic wave-absorbing concrete, sets the water-absorbent resin between adjacent printing layers, realizes the precise control of the shape, pore structure and distribution of the water-absorbent resin through a control device of the impedance gradient, realizes the design and optimization of the impedance gradient, can realize the uniform distribution of the water-absorbent resin in the concrete and the formation of ideal forms, and is favorable for obtaining a concrete material with good consistency and strong wave-absorbing specificity for specific electromagnetic wave bands.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a preparation method and a component of impedance gradient water-absorbent resin reinforced electromagnetic wave-absorbing concrete, which are used for creatively preparing the water-absorbent resins with different equivalent volume doping amounts and impedance gradients into the 3D printing electromagnetic wave-absorbing concrete. The impedance gradient water-absorbent resin reinforced electromagnetic wave-absorbing concrete has the advantages of higher reliability, wider impedance distribution range and the like besides the electromagnetic wave-absorbing performance of the traditional uniform concrete, can control fixed wavelength and wave-absorbing frequency bands, can realize mass production of uniform components, and improves the production efficiency, so that the invention is beneficial to promoting the application of 3D printing concrete in practical engineering.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
a preparation method of impedance gradient water-absorbent resin reinforced electromagnetic wave-absorbing concrete, which comprises the following steps of;
acquiring electromagnetic wave-absorbing concrete slurry capable of 3D printing;
determining the mass of each layer of electromagnetic wave-absorbing concrete slurry during 3D printing, and determining the mass of the dried water-absorbing resin added with equivalent volume doping amount in each layer according to the mass of each layer of electromagnetic wave-absorbing concrete slurry;
the equivalent volume doping amount of each layer is different from bottom to top, and the gradient increment is formed;
when printing, after printing a layer of electromagnetic wave-absorbing concrete slurry, arranging an impedance gradient control device right above the electromagnetic wave-absorbing concrete slurry, and then throwing the dried water-absorbing resin with determined mass on the impedance gradient control device, so that the water-absorbing resin is uniformly distributed on the surface layer of the printed electromagnetic wave-absorbing concrete slurry in an array manner;
printing the next layer of electromagnetic wave-absorbing concrete slurry, and uniformly paving dry water-absorbing resin by using a control device of impedance gradient; repeating the above process until the last layer of electromagnetic wave-absorbing concrete slurry is obtained and dry water-absorbing resin is paved, wherein the dry water-absorbing resin absorbs water in the electromagnetic wave-absorbing concrete slurry continuously and greatly in the printing process;
and then maintaining and watering at regular time, drying, and taking out the water-absorbent resin on the surface layer to obtain the spherical water-absorbent resin electromagnetic wave-absorbing concrete with the impedance gradient matching layer.
The control device of the impedance gradient is of a structure with circular through holes distributed in an array, and the diameter of each circular through hole is slightly larger than that of the dried water absorbent resin and smaller than that of the water absorbent resin after the water absorbent resin is completely saturated by water absorption.
The control device of the impedance gradient has various specifications, and the control devices of the impedance gradients of different specifications have different circular through hole densities.
The equivalent volume doping amount of the dry water absorbing resin is in the range of 20-60%.
The electromagnetic wave-absorbing concrete slurry capable of being printed in 3D comprises the following components in parts by weight: 42.5# Portland cement: 4-6 parts of silica fume: 0.4 to 0.6 part of quartz sand: 4.8-5.2 parts of copper slag: 1.4 to 1.6 portions of thickener: 0.002-0.006 part of water reducing agent: 0.009-0.011 parts of water: 1.7 to 1.9 portions.
The thickener is carboxymethyl cellulose, and the specification is 20 ten thousand viscosity; the particle size of the quartz sand is 90-110 meshes, and the water reducer is a melamine water reducer, and the model is F10; the water-absorbing resin is spherical polyvinyl alcohol water-absorbing resin, and the density of the non-water-absorbing resin is 1.141g/cm 3 The average diameter of the particles of the water-absorbent resin which does not absorb water is 0.5-1 mm; the average diameter of the particles after water absorption and saturation is 2-3 mm.
The preparation process of the electromagnetic wave-absorbing concrete slurry capable of being printed in 3D is as follows: mixing and stirring the ordinary Portland cement, the silica fume, the quartz sand and the copper slag uniformly; then adding a thickening agent into the mixture, and uniformly mixing and stirring the mixture; adding the water reducer and water, mixing and stirring uniformly, and stopping stirring when the water reducer and the water are stirred uniformly to obtain slurry; finally, the slurry is sent into a printing nozzle of a 3D printer, and the outlet cross section area of the printing nozzle is set to be 140mm 2 The horizontal printing speed is 80-120 cm/min, the vertical printing speed is 0.2-0.4 m/h, and the extrusion speed is 0.03-0.05 m 3 And/h then 3D printing.
The concrete obtained by the preparation method can realize control on fixed wavelength and wave absorption frequency bands, and can realize mass production of components with electromagnetic wave absorption consistency.
The invention also protects an impedance gradient water-absorbent resin reinforced electromagnetic wave-absorbing concrete member, which comprises a plurality of layers of 3D printing structures, wherein a cavity structure formed by expanding and drying water-absorbent resins distributed in a uniform array is arranged between two adjacent layers of 3D printing structures; the surface layer of the component is provided with a super-surface array formed by swelling and drying the water-absorbent resin.
The member has a three-layer structure, the equivalent volume doping amount of each layer added with the water absorbent resin along the thickness direction is increased, the surface layer is the matching layer filled with the water absorbent resin most, the bottom layer is a strong absorption layer, and the middle is a transition-loss layer.
Compared with the prior art, the invention has the beneficial effects that:
1. improving electromagnetic wave absorption performance: the impedance gradient water-absorbent resin is prepared into the 3D printing electromagnetic wave-absorbing concrete, spherical water-absorbent resin is filled in the electromagnetic wave-absorbing concrete slurry of the adjacent layer, and the process steps of timing maintenance, watering, shrinkage drying and the like are carried out, so that a regular air cavity is finally formed, the air cavity can be equivalently a closed cell honeycomb structure, and then the electromagnetic wave-absorbing concrete slurry and the water-absorbent resin are combined to form an air-concrete-conductive material multiphase composite regular structure, so that the matching performance of the impedance of the concrete composite material and the impedance of the electromagnetic wave in space can be effectively improved, and the direct reflection effect caused by the electromagnetic wave material is reduced; the impedance matching difference between the material and the free space is reduced, the gradual reduction of the impedance of the material along the incident direction of the electromagnetic wave is optimized, so that the electromagnetic wave completely enters the material to generate loss, the electromagnetic protection effect of wide frequency band and high absorption can be achieved, and the design difficulty that the single-layer wave-absorbing structure simultaneously meets the optimal impedance matching and absorption efficiency in the wide frequency band is solved. The wave absorbing layer can absorb electromagnetic waves for multiple times, so that consumption of the electromagnetic waves after entering the material is increased, and secondary propagation of the electromagnetic waves is reduced. Based on the principle, the absorption bandwidth of electromagnetic waves is further improved.
2. The multi-layer structure design improves the absorption bandwidth: the multilayer structure is usually at the cost of the reduction of mechanical properties, so that the cement-based wave absorbing material is not suitable for a too complex structure, and is generally only designed into a double-layer or three-layer flat plate structure. Since electromagnetic waves are reflected and refracted once at each interface of the multilayer structure, not only the loss probability of the electromagnetic waves in the medium is increased, but also part of reflected waves and incident waves disappear due to interference, which is very advantageous for widening the absorption frequency band. Meanwhile, the impedance matching performance can be improved by adjusting the equivalent volume doping amount of the water-absorbent resin, and the uniformity of distribution can be adjusted by the porosity of the control device of impedance gradient, so that electromagnetic waves can generate multiple reflections and interference in the material to achieve the purpose of loss. A strong absorption over a broad frequency range is achieved. The electric loss and the magnetic loss mechanism in the wave absorbing material are further enhanced, so that electromagnetic wave energy is effectively converted into other forms, and the wave absorbing performance is improved.
3. Impedance gradient enhancement: while the traditional wave-absorbing material has the problems of narrow absorption band, weak absorption performance and the like, the invention realizes the control of impedance gradient by utilizing the 3D printing technology and the water-absorbing resin material, and can accurately control the shape, pore structure and distribution of the water-absorbing resin. Compared with the traditional wave-absorbing material, the invention can more effectively match the impedance of electromagnetic waves and improve the absorption effect. And a functionally gradient electromagnetic wave-absorbing composite material system with gradually changed impedance is established, so that the design requirements of optimal impedance matching and absorption efficiency in a wide frequency range are met.
4. Accurate personalized design and improved production efficiency: the invention can precisely control the form and distribution of the water-absorbent resin by using the control device of the impedance gradient, realize the manufacture of complex structures, and realize the uniform distribution of the water-absorbent resin in the concrete and the formation of ideal forms by adjusting printing parameters, the layer structure of the components and the particle size of the water-absorbent resin. Compared with the traditional preparation method, such as an impregnation method or a coating method, the method can realize personalized customization more flexibly, and meet the requirements of different application fields. The 3D printing technology has higher production efficiency and can rapidly prepare the water-absorbent resin material. Through automatic printing process, can batch production have the water-absorbent resin component of uniformity, improve production efficiency and guarantee product quality's stability.
5. The application fields are wide: the water-absorbent resin reinforced electromagnetic wave-absorbing concrete has various applications in engineering, including the fields of electromagnetic wave absorption, structural vibration reduction, noise control, sustainable construction and the like. The water-absorbent resin reinforced electromagnetic wave-absorbing concrete can effectively absorb electromagnetic wave energy and convert the electromagnetic wave energy into other forms of energy, thereby eliminating, weakening or isolating electromagnetic waves. And the three-dimensional space structure with air cavities inside and the regular inner shell skeleton structure make the structure excellent in vibration reduction and buffering. The shock absorber can absorb and disperse impact energy, reduce vibration transmission and improve shock resistance and vibration reduction effect of the structure. And can also be used in the noise control field. It can reduce the propagation and reflection of sound wave, reduce noise level and improve the comfort of indoor and outdoor environment. And has better sustainability. Its special properties and controllability make it a potential material that can provide innovative solutions for various projects.
6. The environmental protection benefit is high, clings to the double carbon policy: the invention adopts a large amount of copper slag as industrial waste, thereby greatly reducing the damage to the environment and ecology caused by using natural sand stone, reducing the price of 3D printing concrete materials, achieving the effect of green environmental protection and being beneficial to promoting the actual engineering application of 3D printing concrete. Meanwhile, the water-absorbent resin is an environment-friendly material, does not contain harmful substances and does not pollute the environment. Therefore, by combining the 3D printing technology and the application of the water-absorbent resin material, an effective background technology can be provided for electromagnetic wave-absorbing concrete so as to solve the problems of electromagnetic wave interference, radiation pollution and the like, and a more reliable solution is provided for the application in various fields. By increasing the outlet cross section area of the spray head and reducing the horizontal and vertical printing speeds and extrusion speeds, the printer is effectively combined with the control device of the impedance gradient, and the aim is to ensure that the control device of the impedance gradient can uniformly distribute the water-absorbent resin with the same particle size and a given volume doping amount so as to realize mass production of consistent components and improve the production efficiency.
Drawings
FIG. 1 is a schematic diagram showing the structure of an embodiment of a control device for impedance gradient, in which the hole density is gradually increased from (a) - (c) on the control device.
FIG. 2 is a schematic structural diagram of printed components with different impedance matching layers, wherein the hole density of the impedance gradient control device used in each layer in (a) is different, the hole density is gradually increased from bottom to top, the water absorbent resin with different equivalent volume doping amounts is paved in each layer, and the equivalent volume doping amounts are uniformly distributed by using the high-density impedance gradient control device; (b) The pore density of the control device of the impedance gradient used in each layer is the same, the impedance gradient change is controlled by the water-absorbent resin with different volume doping amounts, and the average value of the three equivalent volume doping amounts in the components (a) and (b) is equal.
Fig. 3 is a graph of a 3D printed electromagnetic wave absorbing concrete sample at different equivalent volume doping amounts.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
When the preparation method is used for printing, the quality of the electromagnetic wave-absorbing concrete slurry which is not added is needed to be obtained, then the water-absorbing resin with equivalent volume doping amount is determined according to the obtained result, the water-absorbing resin material which is not absorbed by water is uniformly distributed on each layer of the printed concrete slurry, the water-absorbing resin with uniform distribution, same particle size and given volume doping amount is paved through the impedance gradient control device, the protection is carried out by using the protection film, watering and shrinking drying are carried out at fixed time, and then the spherical water-absorbing resin electromagnetic wave-absorbing concrete with the impedance gradient matching layer is obtained through 3D printing. The control device of impedance gradient has multiple specifications, the aperture of different specifications is the same but the hole density is different (see fig. 1, the frequency band can be flexibly controlled through unifying the aperture), the impedance is adjusted through the difference of the hole density, the water-absorbent resin can be uniformly distributed at each hole position through the control device of impedance gradient, the accurate laying and uniform distribution of the water-absorbent resin are realized, after the water-absorbent resin enters the surface of the slurry, the water-absorbent resin forms a whole with the slurry after passing through the control device of impedance gradient due to the certain adhesive property of the slurry itself, and is fixed at the falling position, when the doping amount of the water-absorbent resin is more, the local accumulation state is presented at the falling position, and the whole of all local accumulation state areas also presents the characteristic of uniform array distribution.
The control device for the impedance gradient is a thin plate, the size of the thin plate is consistent with that of the single-layer printing structure, the open area can cover the inside of the single-layer printing structure, the thickness of the thin plate is 0.5 cm to 2.5cm, the thin plate is at a certain distance from the printing layer and is not tightly attached to the printing layer, and the water-absorbent resin can be in a free falling state when coming out of the circular through holes.
The invention utilizes the particle size input of the spherical water-absorbent resin with the same size to control specific wavelength and wave-absorbing frequency range, so that the electromagnetic wave-absorbing frequency range has controllability and flexibility, can realize batch production and improves the production efficiency and the stability of products.
Examples
The invention relates to impedance gradient water-absorbing resin reinforced electromagnetic wave-absorbing concrete, which is prepared by the following steps:
s1, mixing 4-6 parts by weight of ordinary Portland cement, 0.4-0.6 part by weight of silica fume, 4.8-5.2 parts by weight of quartz sand and 1.4-1.6 parts by weight of copper slag uniformly;
s2, adding 0.002-0.006 parts of thickener into the step S1, and uniformly mixing and stirring;
s3, adding 0.009-0.011 part of water reducer and 1.7-1.9 parts of water into the step S2, uniformly mixing, stopping stirring when the water reducer and the water reducer are uniformly mixed, controlling the stirring time to be about 450 seconds, fully stirring the water reducer, simultaneously preventing the water loss caused by overlong stirring time, and enabling the concrete to harden prematurely, thereby weakening the interference cancellation capability and reducing the electromagnetic wave absorbing performance.
S4, conveying the concrete obtained in the step S3 into a printing nozzle of a 3D printer, and setting the outlet cross section of the printing nozzle to be 140mm 2 The horizontal printing speed is 80-120 cm/min,the vertical printing speed is 0.2-0.4 m/h, the extrusion speed is 0.03-0.05 m 3 And/h then printing.
S5, when printing is carried out, after a layer of electromagnetic wave-absorbing concrete slurry is printed, setting an impedance gradient control device right above the electromagnetic wave-absorbing concrete slurry, and then throwing the dried water-absorbing resin with determined mass on the impedance gradient control device, so that the water-absorbing resin is uniformly distributed on the surface layer of the printed electromagnetic wave-absorbing concrete slurry in an array manner;
printing the next layer of electromagnetic wave-absorbing concrete slurry, and uniformly paving dry water-absorbing resin by using a control device of impedance gradient; repeating the above process until the last layer of electromagnetic wave-absorbing concrete slurry is obtained and dry water-absorbing resin is paved, wherein the dry water-absorbing resin absorbs water in the electromagnetic wave-absorbing concrete slurry continuously and greatly in the printing process;
and then maintaining and watering at regular time, drying, and taking out the water-absorbent resin on the surface layer to obtain the spherical water-absorbent resin electromagnetic wave-absorbing concrete with the impedance gradient matching layer.
According to the invention, the concrete slurry is printed, and the printed structure is subjected to relevant performance tests, namely electromagnetic wave absorption performance evaluation and 3D printing performance test, so that the concrete slurry can realize 3D printing according to the test, and the 3D printing requirement is met. Experiments show that the component prepared according to the preparation method can ensure the smooth printing process on the premise of meeting the proposed printing requirement, and the printed structure is stable and firm and has better wave absorbing performance on a specific frequency band.
The electromagnetic wave absorption reflectivity test adopts an arched frame reflection method, and uses a vector network analyzer (Agilent N5232A) to emit electromagnetic waves, and the electromagnetic wave absorption reflectivity of the material is tested through the transmission of a transmitting head and a receiving head. The electromagnetic wave absorbing performance test of the invention refers to the national military standard method for testing the reflectivity of radar absorbing materials (GJB 2038-1994). The concrete involved in the electromagnetic wave-absorbing reflectivity test must undergo standard curing (relative humidity 95.+ -. 5% and curing temperature 20.+ -. 1 ℃) for at least 28 days. After curing, the concrete test block is dried at a low temperature of 60 ℃ to reduce the influence of the moisture content on the electromagnetic wave reflectivity. A 180mm smooth aluminum plate was then placed under the test block and tested in the 1-18GHz band.
Seven groups of experiments are set according to the equivalent volume mixing amount of the water-absorbent resin (the volume after water absorption of the water-absorbent resin/the volume of the concrete without the water-absorbent resin), the thickness of the wave-absorbing layer (the layer of the wave-absorbing layer is formed by the concrete and the water-absorbent resin) is 21mm, the impedance gradient difference is determined by the equivalent volume mixing amount of the water-absorbent resin, the equivalent volume mixing amount of the water-absorbent resin of each layer is set to be distributed in equal difference, the experiment groups are set according to the table 1, the electromagnetic protection test is carried out on the materials obtained by each group, the experiment groups 3, 5 and 7 sequentially reduce from near to far according to the distance near a concrete matrix, the increasing trend is presented until the outermost matching layer is matched with the free space impedance, the impedance matching capability of the air-concrete-conductive material can be increased, the electromagnetic wave absorption efficiency of the material is improved, and the component obtained by the preparation method can have better absorption effect (bandwidth) and peak value on a frequency band and is more uniform, and is favorable for processing the electromagnetic wave-absorbing material in a special frequency band. The test results are shown below:
table 1 experimental group impedance gradient water-absorbing resin enhanced electromagnetic wave-absorbing concrete electromagnetic shield electromagnetic parameters
Note that: the electromagnetic frequency range of the electromagnetic parameter test is 2-18 GHz; the frequency bandwidth is the frequency bandwidth when the electromagnetic wave reflectivity is higher than-10 dB.
Experimental results show that the effect is best when the volume mixing amount of the water absorbent resin from the bottom layer to the middle layer to the surface layer is 10% -20% -30%. The absorption rate of the water-absorbent resin is up to more than 90% in the range of 14.48GHz, and the highest electromagnetic wave reflectivity is 22.572dB, which is only 2.64dB lower than that of the water-absorbent resin with uniform 60% volume mixing amount. In addition, the absorption bandwidth was greater in the impedance gradients of experimental groups 3, 5, 7 compared to experimental groups 2, 4, 6. Experiment group 6, although the highest reflectance of electromagnetic waves was lower, was relatively narrow in its bandwidth and compared with consumables.
From the experimental results, it can be seen that in the case where the impedance becomes gradually smaller in the incident direction of the electromagnetic wave, the electromagnetic wave enters the inside of the material while being lost, and the maximum absorption effect is achieved at the strong absorption layer. Because the electromagnetic wave can be reflected and refracted at each interface of the multilayer structure, the loss probability of the electromagnetic wave in the medium is increased, and meanwhile, partial reflected wave and incident wave can be mutually counteracted by interference, so that the expansion of the absorption frequency band is facilitated. In addition, the water-absorbent resin with reasonable selection of particle size and volume doping amount can also improve impedance matching performance, so that electromagnetic waves are reflected and interfered for multiple times in the material, thereby increasing loss effect and realizing strong absorption in a wider frequency range. By reducing the impedance matching difference between the material and the free space and optimizing the gradual reduction of the material impedance along the incidence direction of electromagnetic waves, the electromagnetic waves can completely enter the material and generate loss, and the design difficulty that the single-layer wave-absorbing structure simultaneously meets the optimal impedance matching and absorption efficiency in a wide frequency band is solved. The wave absorbing layer can absorb electromagnetic waves for multiple times, so that consumption of the electromagnetic waves after entering the material is increased, secondary propagation of the electromagnetic waves is reduced, and further the absorption bandwidth of the electromagnetic waves is improved.
The invention is applicable to the prior art where it is not described.
Claims (9)
1. The preparation method of the impedance gradient water-absorbent resin reinforced electromagnetic wave-absorbing concrete is characterized by comprising the following steps of;
acquiring electromagnetic wave-absorbing concrete slurry capable of 3D printing;
determining the mass of each layer of electromagnetic wave-absorbing concrete slurry during 3D printing, and determining the mass of the dried water-absorbing resin added with equivalent volume doping amount in each layer according to the mass of each layer of electromagnetic wave-absorbing concrete slurry;
the equivalent volume doping amount of each layer is different from bottom to top, and the gradient increment is formed;
when printing, after printing a layer of electromagnetic wave-absorbing concrete slurry, arranging an impedance gradient control device right above the electromagnetic wave-absorbing concrete slurry, and then throwing the dried water-absorbing resin with determined mass on the impedance gradient control device, so that the water-absorbing resin is uniformly distributed on the surface layer of the printed electromagnetic wave-absorbing concrete slurry in an array manner;
printing the next layer of electromagnetic wave-absorbing concrete slurry, and uniformly paving dry water-absorbing resin by using a control device of impedance gradient; repeating the above process until the last layer of electromagnetic wave-absorbing concrete slurry is obtained and dry water-absorbing resin is paved, wherein the dry water-absorbing resin absorbs water in the electromagnetic wave-absorbing concrete slurry continuously and greatly in the printing process;
then maintaining and watering at regular time, drying, and taking out the water-absorbent resin on the surface layer to obtain spherical water-absorbent resin electromagnetic wave-absorbing concrete with the impedance gradient matching layer;
the control device of the impedance gradient is of a structure with circular through holes distributed in an array, and the diameter of each circular through hole is slightly larger than that of the dried water absorbent resin and smaller than that of the water absorbent resin after the water absorbent resin is completely saturated by water absorption.
2. The method of claim 1, wherein the control means for impedance gradients has a plurality of specifications, and the control means for impedance gradients of different specifications has different circular via densities.
3. The method according to claim 1, wherein the equivalent volume doping amount of the dried water absorbent resin is in the range of 20 to 60%.
4. The preparation method of claim 1, wherein the electromagnetic wave-absorbing concrete slurry capable of 3D printing comprises the following components in parts by weight: 42.5# Portland cement: 4-6 parts of silica fume: 0.4 to 0.6 part of quartz sand: 4.8-5.2 parts of copper slag: 1.4 to 1.6 portions of thickener: 0.002-0.006 part of water reducing agent: 0.009-0.011 parts of water: 1.7 to 1.9 portions.
5. The preparation method according to claim 4The thickener is carboxymethyl cellulose, and the specification is 20 ten thousand viscosity; the particle size of the quartz sand is 90-110 meshes, and the water reducer is a melamine water reducer, and the model is F10; the water-absorbing resin is spherical polyvinyl alcohol water-absorbing resin, and the density of the non-water-absorbing resin is 1.141g/cm 3 The average diameter of the particles of the water-absorbent resin which does not absorb water is 0.5-1 mm; the average diameter of the particles after water absorption and saturation is 2-3 mm.
6. The preparation method of claim 4, wherein the preparation process of the electromagnetic wave-absorbing concrete paste capable of 3D printing is as follows: mixing and stirring the ordinary Portland cement, the silica fume, the quartz sand and the copper slag uniformly; then adding a thickening agent into the mixture, and uniformly mixing and stirring the mixture; adding the water reducer and water, mixing and stirring uniformly, and stopping stirring when the water reducer and the water are stirred uniformly to obtain slurry; finally, the slurry is sent into a printing nozzle of a 3D printer, and the outlet cross section area of the printing nozzle is set to be 140mm 2 The horizontal printing speed is 80-120 cm/min, the vertical printing speed is 0.2-0.4 m/h, and the extrusion speed is 0.03-0.05 m 3 And/h then 3D printing.
7. The preparation method according to claim 1, wherein the concrete obtained by the preparation method can realize control of fixed wavelength and wave absorption frequency band, and can mass-produce members with electromagnetic wave absorption consistency.
8. An impedance gradient water-absorbent resin reinforced electromagnetic wave-absorbing concrete member obtained by the preparation method according to any one of claims 1 to 7, which is characterized in that the member comprises a plurality of layers of 3D printing structures, and a cavity structure formed by expanding and drying water-absorbent resins distributed in a uniform array is arranged between two adjacent layers of 3D printing structures; the surface layer of the component is provided with a super-surface array formed by swelling and drying the water-absorbent resin.
9. The member according to claim 8, wherein the member has a three-layer structure in which the equivalent volume doping amount of each layer added with the water absorbent resin in the thickness direction becomes large, the surface layer is the most water absorbent resin filled matching layer, the bottom layer is the strong absorption layer, and the middle is the transition-loss layer.
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| CN104961411A (en) * | 2015-07-01 | 2015-10-07 | 黄贺明 | High-performance powder concrete for 3D (three-dimensional) printing |
| CN109516744A (en) * | 2019-01-21 | 2019-03-26 | 河北工业大学 | A kind of waveform electromagnetic wave absorption concrete structure based on 3D printing |
| CN110395967A (en) * | 2019-07-18 | 2019-11-01 | 河北工业大学 | Spray 3D printing functionally gradient microwave defense material and preparation method thereof |
| CN116161907A (en) * | 2022-12-08 | 2023-05-26 | 中国人民解放军陆军勤务学院 | Functionally gradient concrete buffering energy dissipation material, preparation method and application |
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| CN104961411A (en) * | 2015-07-01 | 2015-10-07 | 黄贺明 | High-performance powder concrete for 3D (three-dimensional) printing |
| CN109516744A (en) * | 2019-01-21 | 2019-03-26 | 河北工业大学 | A kind of waveform electromagnetic wave absorption concrete structure based on 3D printing |
| CN110395967A (en) * | 2019-07-18 | 2019-11-01 | 河北工业大学 | Spray 3D printing functionally gradient microwave defense material and preparation method thereof |
| CN116161907A (en) * | 2022-12-08 | 2023-05-26 | 中国人民解放军陆军勤务学院 | Functionally gradient concrete buffering energy dissipation material, preparation method and application |
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