CN115988861A - Broadband wave absorbing material, broadband wave absorbing plate and preparation method - Google Patents
Broadband wave absorbing material, broadband wave absorbing plate and preparation method Download PDFInfo
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Abstract
The application discloses a broadband wave-absorbing material, a broadband wave-absorbing plate and a preparation method. The broadband wave-absorbing material comprises an impedance matching wave-absorbing material, a porous wave-absorbing material and a resistance dielectric loss wave-absorbing material, wherein the aperture of the porous wave-absorbing material is 5-30 mu m, and the porosity is 50-70%. The impedance matching wave-absorbing material can reduce the reflectivity and improve the electromagnetic wave absorption rate; the porous wave-absorbing material can increase the frequency band of the loss electromagnetic wave energy, especially increase the high-frequency loss; the resistance dielectric loss wave-absorbing material can improve the energy loss rate of electromagnetic waves, so that the broadband wave-absorbing material and the broadband wave-absorbing plate containing the broadband wave-absorbing material have the effects of broadband wave absorption and high energy loss rate. The preparation method of the broadband wave absorbing plate comprises the steps of carrying out first mixing treatment on the three groups of materials and then carrying out first film forming treatment, or respectively carrying out second film forming treatment on the three groups of materials and then sequentially carrying out laminating treatment.
Description
Technical Field
The application belongs to the technical field of electromagnetic wave absorbing materials, and particularly relates to a broadband wave absorbing material, a broadband wave absorbing plate and a preparation method.
Background
With the popularization of wireless devices in human life, electromagnetic wave pollution becomes a large pollution source harmful to human health, meanwhile, a large amount of electromagnetic waves cause serious electromagnetic interference problems to the wireless devices, and an electromagnetic wave absorbing material (wave absorbing material) is a material with the effects of absorbing and consuming electromagnetic wave energy, so that the electromagnetic wave pollution and the electromagnetic wave interference can be effectively dealt with. After electromagnetic waves enter the wave-absorbing material, the electromagnetic waves need to be lost in the material, and the wave-absorbing material can be divided into a resistance loss material, a dielectric loss material and a magnetic loss material according to a loss mechanism. Known wave-absorbing materials include carbon-based wave-absorbing materials such as graphite and carbon fiber, iron-based wave-absorbing materials such as ferrite, ceramic-based wave-absorbing materials such as silicon carbide, chiral materials, plasma materials and the like. In engineering application, the wave-absorbing material can be made into a coating or a patch; the patch is convenient to process and transport, convenient to construct, flexible, high in designability and more suitable for being applied to the field of electronic products.
However, the wireless devices radiating electromagnetic waves are various in types and increasingly dense in distribution, the frequency of the radiated electromagnetic waves is increasingly wide, the intensity of the radiated electromagnetic waves is increasingly strong, and the requirements of wide wave-absorbing frequency range (wide wave-absorbing frequency band) and high energy loss rate of the electromagnetic waves are provided for the wave-absorbing material. The electromagnetic wave energy loss rate is generally characterized by 'reflection loss' in the industry, the unit of the reflection loss is decibel (dB), the smaller the reflection loss of the wave-absorbing material is, the better the reflection loss is, and when the reflection loss is respectively less than-10 dB, -20dB and-30 dB, the wave-absorbing material can absorb more than 90%, 99% and 99.9% of the electromagnetic wave energy. The single wave-absorbing material is difficult to meet the requirements of wide wave-absorbing frequency range and high electromagnetic wave energy loss rate, so that multiple wave-absorbing materials are often used in combination in the prior art to enlarge the wave-absorbing frequency range and enhance the wave-absorbing effect, the wave-absorbing strength is better in the L-Ku wave band, namely the low-frequency wave band of 1 GHz-18 GHz, but the problems of narrow wave-absorbing frequency band and low electromagnetic wave energy loss rate still exist in the whole wave-absorbing material.
Disclosure of Invention
The application aims to overcome the defects in the prior art, and provides a broadband wave-absorbing material, a broadband wave-absorbing plate and a preparation method thereof, so as to solve the technical problems of narrow wave-absorbing frequency band and low energy loss rate of electromagnetic waves of the existing wave-absorbing material.
In order to achieve the above object, in a first aspect of the present application, a broadband wave-absorbing material is provided. The broadband wave-absorbing material comprises an impedance matching wave-absorbing material, a porous wave-absorbing material and a resistance dielectric loss wave-absorbing material, wherein the aperture of the porous wave-absorbing material is 5-30 mu m, and the porosity is 50-70%.
The impedance matching wave-absorbing material contained in the broadband wave-absorbing material can reduce the reflectivity of electromagnetic waves when the electromagnetic waves are incident and improve the absorptivity of the electromagnetic waves; the porous wave-absorbing material can increase the frequency band of the loss electromagnetic wave energy, especially increase the high-frequency loss, so that the porous wave-absorbing material has the electromagnetic wave loss effect in the frequency band of 1 GHz-40 GHz (L-Ka waveband) and has wide frequency range; the resistance dielectric loss wave-absorbing material can convert absorbed electromagnetic wave energy into heat energy, and the energy loss rate of the electromagnetic wave is greatly improved. Therefore, the broadband wave-absorbing material has the effects of broadband wave absorption and high energy loss rate.
In some embodiments, the porous absorbing material comprises at least one of porous nickel, porous carbon, hollow glass microspheres.
In some embodiments, the resistive dielectric loss wave absorbing material comprises at least one of graphite, amorphous carbon, lithium titanate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate.
In some embodiments, the attenuation coefficient of the electromagnetic wave of the resistance dielectric loss wave-absorbing material in the frequency band of 1 GHz-40 GHz is 400-800.
In some embodiments, the impedance matching wave absorbing material comprises at least one of aluminum oxide, ferric oxide, silicon dioxide, titanium dioxide, and calcium carbonate.
In some embodiments, the impedance matching absorbing material has a resistivity of 10 5 Ω·m～10 6 Ω·m。
In some embodiments, the impedance matching coefficient of the impedance matching wave-absorbing material in the frequency band of 1 GHz-40 GHz is 0.8-1.
In some embodiments, the mass ratio of the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistive dielectric loss wave-absorbing material is (40-70): (30-50): (60-90).
In a second aspect of the present application, a broadband wave absorbing plate is provided. The broadband wave absorbing plate contains the broadband wave absorbing material applied by the upper text.
The broadband wave absorbing plate contains the broadband wave absorbing material applied by the previous text, so that the broadband wave absorbing plate has the effects of broadband wave absorption and high energy loss rate.
In some embodiments, the broadband wave absorbing plate comprises a first layer, a second layer and a third layer which are sequentially stacked to form a sandwich structure, wherein the material of the first layer comprises an impedance matching wave absorbing material contained in the broadband wave absorbing material applied in the above application; the material of the second layer comprises porous wave-absorbing material contained in the broadband wave-absorbing material applied in the above text; the third layer of material comprises the resistance dielectric loss wave-absorbing material contained in the broadband wave-absorbing material applied in the above text.
In some embodiments, the first layer has a thickness of 0.3mm to 0.5mm.
In some embodiments, the second layer has a thickness of 1.0mm to 1.5mm.
In some embodiments, the third layer has a thickness of 0.5mm to 1.0mm.
In some embodiments, the first, second and third layers independently further comprise a substrate.
In some embodiments, the impedance matching wave absorbing material comprises 40wt% to 70wt% of the total mass of the first layer.
In some embodiments, the porous wave-absorbing material accounts for 30wt% to 50wt% of the total mass of the second layer.
In some embodiments, the resistive dielectric loss wave absorbing material comprises 60wt% to 90wt% of the total mass of the third layer.
In some embodiments, the substrate comprises at least one of nitrile rubber, styrene butadiene rubber, polyurethane rubber, ethylene propylene diene monomer rubber.
In a third aspect of the present application, a method for manufacturing a broadband wave absorbing plate is provided. The preparation method of the broadband wave absorbing plate comprises the following steps:
performing first mixing treatment on an impedance matching wave-absorbing material, a porous wave-absorbing material and a resistance dielectric loss wave-absorbing material to obtain a mixture;
carrying out first film forming treatment on the mixture to obtain a broadband wave absorbing plate;
or
Respectively carrying out second film forming treatment on the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material to obtain a first layer, a second layer and a third layer in sequence;
sequentially laminating the first layer, the second layer and the third layer to obtain a broadband wave absorbing plate;
the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material are impedance matching wave-absorbing materials, porous wave-absorbing materials and resistance dielectric loss wave-absorbing materials contained in the broadband wave-absorbing material of the above application.
The broadband wave absorbing plate prepared by the preparation method of the broadband wave absorbing plate has the advantages of wide wave absorbing frequency band, high electromagnetic wave loss rate, stable and reliable quality, controllable process parameters and good consistency.
Drawings
In order to more clearly illustrate the detailed description of the present application or the technical solutions in the prior art, the drawings needed to be used in the detailed description of the present application or the prior art description will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic diagram of a broadband wave-absorbing plate wave-absorbing test result in embodiments 1 to 3 of the present application;
fig. 2 is a schematic structural diagram of a broadband wave-absorbing plate with a three-layer structure according to embodiment 1 of the present application;
FIG. 3 is a schematic flow chart of a method for manufacturing a broadband wave-absorbing plate of the present application;
FIG. 4 is a schematic flow chart of a method for manufacturing a broadband wave-absorbing plate with a three-layer structure according to the present application;
the reference numbers in the detailed description are as follows:
1. a first layer; 2. a second layer; 3. and a third layer.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application more clearly apparent, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In this application, the term "and/or" describes an association relationship of associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
In the present application, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (one) of a, b, or c," or "at least one (one) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, and c may be single or plural, respectively.
It should be understood that, in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The weight of the related components mentioned in the description of the embodiments of the present application may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present application as long as it is scaled up or down according to the description of the embodiments of the present application. Specifically, the mass described in the specification of the embodiments of the present application may be a mass unit known in the chemical industry field such as μ g, mg, g, kg, etc.
In a first aspect, embodiments of the present application provide a broadband wave-absorbing material. The broadband wave-absorbing material comprises an impedance matching wave-absorbing material, a porous wave-absorbing material and a resistance dielectric loss wave-absorbing material, wherein the aperture of the porous wave-absorbing material is 5-30 microns, and the porosity is 50-70%.
The impedance matching wave-absorbing material in the broadband wave-absorbing material in the embodiment of the application refers to the impedance matching of the material and the external space. Specifically, when an electromagnetic wave enters a wave-absorbing material with impedance Z1 from an external space with impedance Z0, one part of the electromagnetic wave is reflected, and the other part of the electromagnetic wave enters the wave-absorbing material, wherein the reflectivity R = (Z0-Z1)/(Z0 + Z1), and the impedance is equal to the square root of the quotient of the magnetic permeability divided by the dielectric constant. Obviously, at the interface between the external space and the wave-absorbing material, the reflectivity of the electromagnetic wave in the frequency to be absorbed cannot be too high, otherwise, the electromagnetic wave is reflected and then returns to the external space to be transmitted, so that the reflectivity is low, the electromagnetic wave can enter the wave-absorbing material to the maximum extent, and the wave-absorbing effect is improved. Ideally, when the electromagnetic wave with a certain frequency range is incident, and when Z1= Z0, the reflectivity is 0, which is the most impedance-matched situation, but it is basically impossible to realize in reality, so the closer Z1 is to Z0, that is, the closer the impedance of the impedance-matched wave-absorbing material is to the impedance of the external space when the electromagnetic wave with a certain frequency band is incident, the more the impedance of the impedance-matched wave-absorbing material is, the electromagnetic wave can enter the wave-absorbing material to the maximum extent, which is the meaning of impedance matching. The external space can be determined according to the use scene, for example, the external space is used in the air under most conditions, and the closer the impedance of the impedance matching wave absorbing material is to the impedance of the air in the broadband range of the electromagnetic waves, the better the wave absorbing effect is. Further, since the impedance matching material has resistance, a part of the absorbed electromagnetic waves is consumed in the impedance matching material due to resistance loss.
The porous wave-absorbing material in the broadband wave-absorbing material in the embodiment of the application refers to a wave-absorbing material containing a porous structure. The inventor finds in research that besides the intrinsic electromagnetic loss capability, the materials have a porous structure which has multiple scattering and interference effects on absorbed electromagnetic waves, so that the loss of the electromagnetic waves in the porous wave-absorbing material is further enhanced. In addition, the inventor also finds that the effect of absorbing and losing the electromagnetic waves is obviously improved by selecting the wave-absorbing material with proper pore diameter and porosity. The inventor tests in the research that (1) when the aperture of the porous wave-absorbing material is 5-30 microns, the diameter of the holes is in micron level, and the porosity is larger, so that electromagnetic wave waves with the frequency of more than 18GHz can easily consume electromagnetic energy due to interference, and the loss effect of the porous wave-absorbing material in a high-frequency band is expanded. In an illustrative example, the pore size of the porous wave-absorbing material can be typical, but not limiting, pore sizes of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, and the like. (2) The larger the porosity is, the more easily electromagnetic scattering occurs in the porous wave-absorbing material, and the electromagnetic energy is continuously consumed in the broadband wave-absorbing material, so that the energy loss rate of the electromagnetic wave is improved; in addition, the larger the porosity of the material is, the more beneficial to reducing the density of the material in practical application is, so that the porous wave-absorbing material is lighter. In an exemplary embodiment, the porosity of the porous wave-absorbing material may be 50%, 55%, 60%, 65%, 70%, etc. with typical but not limiting porosities. Therefore, when the porous wave-absorbing material has the pore diameter and the porosity, the broadband wave-absorbing material provided by the embodiment of the application has a wider electromagnetic wave energy loss frequency range and a higher electromagnetic wave energy loss rate.
The resistance dielectric loss wave-absorbing material in the broadband wave-absorbing material in the embodiment of the application refers to a wave-absorbing material with resistance loss and/or dielectric loss effects. The materials can gradually attenuate electromagnetic waves in the materials, and the electromagnetic energy is converted into heat energy to be consumed. (1) The resistance loss wave-absorbing material can enable carriers to cause induced current after absorbing electromagnetic waves, and the induced current can be converted into heat energy to be consumed in the internal transmission process of the material, such as the disclosed materials of silicon carbide, graphite and the like; (2) the dielectric constant has a real part and an imaginary part, and the dielectric loss wave-absorbing material has a higher imaginary part, so that polarization hysteresis can be generated when the frequency of the absorbed electromagnetic wave is higher than the polarization of the material, and the repeated polarization of the dielectric generates the effect similar to 'friction' to convert the electromagnetic energy into heat energy for consumption, such as the disclosed materials of barium titanate and the like. Researches show that the resistance dielectric loss wave-absorbing material has very obvious energy loss rate of electromagnetic waves in a low-frequency band of 1 GHz-18 GHz.
Through research, when the broadband wave-absorbing material in the embodiment of the application comprises the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material, the materials can be multiphase combined type, can also be pairwise combined type, and can also be layered type. When the three types of materials are included, the three types of materials have synergistic effects with each other, so that the frequency range of the absorbed electromagnetic waves is widened, the frequency range of the consumable electromagnetic waves is widened, and the energy loss rate of the electromagnetic waves is greatly enhanced. Therefore, the broadband wave-absorbing material in the embodiment of the application has a broadband electromagnetic wave absorption effect compatible with microwave low-frequency and high-frequency multi-spectrum in a frequency band of 1 GHz-40 GHz, and the bandwidth with reflection loss superior to-10 dB is also very high. Therefore, the broadband wave-absorbing material of the embodiment of the application realizes the wave-absorbing effects of broadband wave absorption and high energy loss rate of electromagnetic waves.
In some embodiments, the mass ratio of the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistive dielectric loss wave-absorbing material may be (40-70): (30-50): (60-90). The mass ratio of the materials can ensure that the broadband wave-absorbing material in the embodiment of the application has the advantages of electromagnetic wave absorption rate, wave-absorbing loss frequency range and electromagnetic wave energy loss rate, and achieves the effects of broadband wave absorption and high loss rate. In an exemplary embodiment, the mass ratio may be 40:35: 60. 50:40: 70. 60:30:80, etc., in a typical, but not limiting, ratio.
In some embodiments, the impedance matching wave absorbing material may include at least one of aluminum oxide, ferric oxide, silicon dioxide, titanium dioxide, and calcium carbonate.
The impedance matching wave-absorbing material is tested to have at least one of the following properties:
the resistivity of the impedance matching wave-absorbing material is 10 5 Ω·m～10 6 Ω · m, in the exemplary case, the resistivity may be 1 × 10 5 Ω·m、3×10 5 Ω·m、6×10 5 Ω·m、1×10 6 Ω · m, etc., typically but not limited to.
The impedance matching coefficient of the impedance matching wave-absorbing material in the frequency band of 1 GHz-40 GHz is 0.8-1, and in an example, the impedance matching coefficient may be a typical but non-limiting coefficient such as 0.8, 0.85, 0.9, 0.95, 1, and the like.
The oxides and/or calcium carbonate or the wave-absorbing material with the resistivity and the impedance matching coefficients are used as the impedance matching wave-absorbing material, so that the wave-absorbing material has a better impedance matching effect with air, can reduce the reflectivity of electromagnetic waves when the electromagnetic waves enter from an external space, and improves the proportion of absorbing the electromagnetic waves.
In some embodiments, the porous absorbing material may include at least one of porous nickel, porous carbon, hollow glass microspheres. The inventor finds that the porous wave-absorbing materials have the intrinsic electromagnetic loss capacity, and when the porous structure has the pore diameter and the porosity, the broadband wave-absorbing material provided by the embodiment of the application can be endowed with a wider electromagnetic wave energy loss frequency range and a higher electromagnetic wave energy loss rate.
In some embodiments, the attenuation coefficient of the electromagnetic wave of the resistive dielectric loss wave-absorbing material in the frequency band of 1 GHz-40 GHz can be 400-800.
The resistance dielectric loss wave-absorbing material is endowed with the capacity of corresponding electromagnetic wave loss by the electromagnetic wave attenuation coefficient of the resistance dielectric loss wave-absorbing material, so that the sufficient loss effect on the low-frequency band from L to Ku is ensured, the electromagnetic waves are rapidly lost in the material, and the wave-absorbing effect of the broadband wave-absorbing material in the embodiment of the application is consolidated. In an exemplary embodiment, the attenuation coefficient of the electromagnetic wave of the resistive dielectric loss wave-absorbing material may be a typical, but not limiting, coefficient of 500, 600, 700, 800, etc.
In some embodiments, the resistive dielectric loss wave absorbing material comprises at least one of graphite, amorphous carbon, lithium titanate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate.
The inventor also finds that some positive and negative electrode materials contained in the recycled lithium battery also have resistance and/or dielectric loss effects, and particularly the electromagnetic wave loss effect of the positive electrode material of the lithium battery is not disclosed and described. Through further research, the positive electrode material and/or the negative electrode material of the lithium battery have the effects of resistance loss and/or dielectric loss, electromagnetic waves can be gradually attenuated in the materials, electromagnetic energy is converted into heat energy through the resistance loss and/or the dielectric loss, and the energy loss rate of the electromagnetic waves is improved. Researches show that the materials have good wave absorbing strength in the low-frequency wave band of L-Ku. In addition, in practical application, the materials can be recovered from waste lithium batteries, so that the environment benefit and the economic benefit are both good.
In a second aspect, embodiments of the present application provide a broadband wave-absorbing plate. The broadband wave absorbing plate comprises the broadband wave absorbing material in each application embodiment. The impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material contained in the broadband wave-absorbing plate can be in a multiphase composite layer structure, can also be in a layer structure formed by compounding two wave-absorbing materials or can be in a layer structure formed by singly using a single material. Because the broadband wave-absorbing material in each application embodiment contains, the broadband wave-absorbing plate in the application embodiment has the effects of wide wave-absorbing frequency range and high electromagnetic wave energy loss rate.
In some embodiments, the broadband wave absorbing plate may include a first layer 1, a second layer 2, and a third layer 3 stacked in sequence to form a sandwich structure, and the material of the first layer 1 may include an impedance matching wave absorbing material included in the broadband wave absorbing material in each of the embodiments; the material of the second layer 2 comprises porous wave-absorbing materials contained in the broadband wave-absorbing materials in the above embodiments; the material of the third layer 3 comprises the resistance dielectric loss wave-absorbing material contained in the broadband wave-absorbing material of each embodiment.
Therefore, the broadband wave absorbing plate has the advantages that materials contained in the broadband wave absorbing material are classified to form the broadband wave absorbing plate with the three-layer structure, wave absorbing and loss effects of materials of all layers can be fully exerted, and the broadband wave absorbing plate has wider wave absorbing frequency and higher electromagnetic wave energy loss rate. The first layer 1 contains an impedance matching wave-absorbing material, so that the effect of impedance matching with the external space and high absorption rate of broadband electromagnetic waves is achieved; the second layer 2 contains porous wave-absorbing materials, so that the wave-absorbing material has the effects of wide wave-absorbing frequency range and high electromagnetic wave energy loss rate; the third layer 3 contains a resistance dielectric loss wave-absorbing material, so that the electromagnetic wave-absorbing material has a strong electromagnetic loss effect and a high electromagnetic wave energy loss rate. Therefore, the broadband wave absorbing plate in the embodiment of the application has the effects of broadband wave absorption and high electromagnetic wave energy loss rate. In practical application, the broadband wave absorbing plate prepared by sequential stacking can enable the first layer 1 to face to the external space for transmitting electromagnetic waves so as to obtain the best wave absorbing effect.
In some embodiments, the thickness of the first layer 1 may be 0.3mm to 0.5mm; the thickness of the second layer 2 may be 1.0mm to 1.5mm; the thickness of the third layer 3 may be 0.5mm to 1.0mm. The thickness ensures that the electromagnetic wave entering the wave absorbing plate has enough space to be absorbed and lost, and is beneficial to the wave absorbing plate to obtain the effects of broadband wave absorption and high energy loss rate of the electromagnetic wave.
In some embodiments, the first layer 1, the second layer 2, and the third layer 3 may independently further include a base material, and the impedance matching wave-absorbing material may account for 40wt% to 70wt% of the total mass of the first layer 1; the porous wave-absorbing material can account for 30-50 wt% of the total mass of the second layer 2; the resistance dielectric loss wave-absorbing material can account for 60wt% -90 wt% of the total mass of the third layer 3.
The first layer 1, the second layer 2 and the third layer 3 of the broadband wave-absorbing plate in the embodiment of the application can independently comprise a substrate. The base material can be the wave-transparent material, and in practical application, the base material can stably hold broadband wave-absorbing material to provide higher impact modulus, environmental resistance and flexibility, endow the broadband wave-absorbing plate who makes and have more stable broadband wave-absorbing effect and stronger wave-absorbing performance, still more convenient design, industrial production, transportation and use in addition. The substrate may include an organic insulating rubber, such as at least one of nitrile rubber, styrene butadiene rubber, urethane rubber, ethylene propylene diene monomer rubber.
Of course, the substrate is not limited to be used in the broadband wave-absorbing plate with the three-layer structure, and when the material included in the broadband wave-absorbing plate in the embodiments of the present application is in other structures or composite forms, the substrate may also be included.
In a third aspect, an embodiment of the present application provides a method for manufacturing a broadband wave-absorbing plate. The preparation method comprises the following steps:
s01: performing first mixing treatment on an impedance matching wave-absorbing material, a porous wave-absorbing material and a resistance dielectric loss wave-absorbing material to obtain a mixture;
s02: and carrying out first film forming treatment on the mixture to obtain the broadband wave absorbing plate.
Or alternatively
S03: respectively carrying out second film forming treatment on the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material to obtain a first layer 1, a second layer 2 and a third layer 3 in sequence;
s04: and sequentially laminating the first layer 1, the second layer 2 and the third layer 3 to obtain the broadband wave absorbing plate.
The impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material in the steps S01 and S03 can be respectively the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material contained in the broadband wave-absorbing material of each embodiment of the above application.
The preparation method of the broadband wave-absorbing material comprises respective preparation methods of two broadband wave-absorbing plates with different structures. The broadband wave absorbing plate prepared by the two preparation methods has the effects of wide electromagnetic wave absorption frequency range and high energy loss rate.
The broadband wave absorbing plate with the multiphase composite structure can be prepared in the steps S01 and S02.
Step S01:
the first mixing treatment in step S01 may be to fully and uniformly mix the broadband wave-absorbing material in each embodiment of the above application to obtain a mixture. The broadband wave-absorbing material and the base material in the embodiments of the above application can also be melted and uniformly mixed, and then refined to obtain a mixture.
Step S02:
the first film forming treatment in step S02 may be to flatten the mixture into a film layer, so as to obtain the broadband wave absorbing plate. Or the mixture containing the base material is processed by hot pressing to obtain a film layer, so as to obtain the broadband wave absorbing plate. The broadband wave absorbing plate prepared by the method has the advantages of wide wave absorbing frequency band, high energy loss rate, excellent wave absorbing effect, controllable preparation method process and stable finished product property.
The broadband wave absorbing plate with the three-layer structure can be manufactured in the steps S03 and S04.
Step S03:
the second film formation process in step S03 may specifically include the steps of:
s031: the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material can be respectively and independently subjected to second mixing treatment with the base material particles, and then refined to obtain three groups of mixed materials.
S032: the three groups of mixed materials can be subjected to hot pressing treatment to obtain three groups of film layers.
The second mixing process in step S031 may be to melt the raw material particles uniformly by an internal mixer. The temperature of the internal mixer can be 60-80 ℃, and the internal mixing time can be 8-12 h. The thinning treatment can be crushing and sieving treatment, and the mesh number of crushing and sieving can be more than 60 meshes. This allows the raw materials to be thoroughly mixed and dispersed into the substrate.
The hot pressing process in step S032 may be performed by heating and extruding the three groups of mixed materials through a two-roll calender, and controlling the thickness of the film through the distance between the two rolls to obtain three groups of film layers. The operating temperature of the roller of the double-roller calendering equipment can be 70-90 ℃. Therefore, the three groups of mixed materials can be made into appropriate thickness, and each layer has excellent wave absorbing effect under the corresponding thickness of the broadband wave absorbing plate in the embodiment.
Step S04:
the laminating treatment in step S04 may be sequentially performed by sequentially laminating the film surfaces according to the order of the first layer 1, the second layer 2, and the third layer 3, and the broadband wave absorbing plate may be prepared by a hot press molding process, specifically, by heating and pressing in a vulcanizer, the operating temperature of the roller of the vulcanizer may be 120 to 150 ℃, the pressure between the steel strip and the roller may be 5 to 15MPa, and the vulcanization linear velocity may be 0.2 to 0.8m/min. Therefore, the broadband wave absorbing plate with a three-layer structure can be prepared, the wave absorbing effect of each layer is fully exerted, and the broadband wave absorbing plate has excellent wave absorbing effects of broadband wave absorption and high electromagnetic wave loss rate.
The broadband wave absorbing plate and the preparation method thereof according to the embodiments of the present application are illustrated by a plurality of specific examples.
1. The embodiment of the broadband wave absorbing plate and the preparation method thereof comprises the following steps:
example 1
The embodiment provides a broadband wave absorbing plate and a preparation method thereof. The broadband wave absorbing plate in the embodiment is a three-layer structure as shown in fig. 2, and the first layer comprises the following components by mass: 40 parts of butadiene acrylonitrile rubber, 30 parts of aluminum oxide and 30 parts of ferric oxide; the second layer comprises the following components in percentage by mass: 70 parts of nitrile-butadiene rubber, 10 parts of porous carbon and 20 parts of hollow glass beads, wherein the aperture of the porous carbon and the hollow glass beads is 8-20 microns, and the porosity is 60%; the third layer comprises the following components in percentage by mass: 10 parts of butadiene acrylonitrile rubber, 50 parts of lithium titanate and 40 parts of nickel cobalt lithium manganate. The thicknesses of the first, second and third layers were 0.4mm, 1.1mm and 0.5mm, respectively. The butadiene acrylonitrile rubber is used as a base material in the first layer to the third layer.
The preparation method of the broadband wave absorbing plate comprises the following steps:
s1, mixing treatment:
putting each layer of raw material particles into an internal mixer respectively and independently according to the mass ratio of each layer of material of the broadband wave absorbing plate in the embodiment, setting the temperature of the internal mixer to be 80 ℃, setting the internal mixing time to be 8h, uniformly smelting, crushing, and sieving by using a 80-mesh screen to obtain three groups of mixed materials;
s2, film forming treatment:
putting the three groups of mixed materials obtained in the step S1 into a double-roller calender with the diameter phi of 150mm and the working width of 500mm respectively, adjusting the distances among rollers to be 0.4mm, 1.1mm and 0.5mm respectively, setting the working temperature of the rollers to be 70 ℃ and the rotation linear speed to be 0.8m/min, and forming continuous films by heating and extruding through double rollers to obtain three groups of film layers;
s3, hot-press forming:
and (3) sequentially laminating the three groups of film layers obtained in the step (S2) according to the sequence of the first layer, the second layer and the third layer, placing the film layers on a winding drum of a vulcanizing machine, setting the working temperature of a roller of the vulcanizing machine to be 120 ℃, setting the pressure facility between a steel belt and the roller to be 10MPa, setting the vulcanizing linear speed to be 0.5m/min, and heating and pressurizing the film layers by the vulcanizing machine for molding to obtain the broadband wave absorbing plate.
Example 2
The embodiment provides a broadband wave absorbing plate and a preparation method thereof. The broadband wave absorbing plate of the embodiment is of a three-layer structure, and the mass proportion of the first layer of components is as follows: 30 parts of polyurethane rubber, 20 parts of alumina, 10 parts of silica and 30 parts of ferric oxide; the second layer comprises the following components in percentage by mass: 50 parts of polyurethane rubber, 40 parts of porous nickel and 10 parts of hollow glass beads, wherein the pore diameter of the porous nickel and the hollow glass beads is 10-20 micrometers, and the porosity is 65%; the third layer comprises the following components in percentage by mass: 10 parts of polyurethane rubber, 50 parts of lithium titanate and 40 parts of nickel cobalt lithium manganate. The thicknesses of the first, second and third layers were 0.4mm, 1.0mm and 0.6mm, respectively. The urethane rubber serves as a base material in the first to third layers.
The preparation method of the broadband wave-absorbing plate comprises the following steps:
s1, mixing treatment:
respectively and independently putting raw material particles of each layer into an internal mixer according to the mass ratio of the materials of each layer of the broadband wave absorbing plate in the embodiment, setting the temperature of the internal mixer to be 70 ℃ and the internal mixing time to be 10h, uniformly smelting, crushing and sieving by a 60-mesh sieve to obtain three groups of mixed materials;
s2, film forming treatment:
putting the three groups of mixed materials obtained in the step S1 into a double-roller calender with the diameter phi of 150mm and the working width of 500mm respectively, adjusting the distances among rollers to be 0.4mm, 1.0mm and 0.6mm respectively, setting the working temperature of the rollers to be 90 ℃ and the rotation linear speed to be 0.8m/min, and forming continuous films by heating and extruding through double rollers to obtain three groups of film layers;
s3, hot press forming:
and (3) sequentially laminating the three groups of film layers obtained in the step (S2) according to the sequence of the first layer, the second layer and the third layer, placing the film layers on a winding drum of a vulcanizing machine, setting the working temperature of the roller of the vulcanizing machine to be 150 ℃, setting the pressure facility between the steel belt and the roller to be 10MPa, setting the vulcanizing linear speed to be 0.6m/min, and heating and pressurizing the film layers by the vulcanizing machine for molding to obtain the broadband wave absorbing plate.
Example 3
The embodiment provides a broadband wave absorbing plate and a preparation method thereof. The broadband wave absorbing plate of the embodiment is of a three-layer structure, and the mass proportion of the first layer of components is as follows: 50 parts of ethylene propylene diene monomer, 10 parts of alumina, 10 parts of silica and 30 parts of ferric oxide; the second layer comprises the following components in percentage by mass: the ethylene propylene diene monomer comprises 50 parts of ethylene propylene diene monomer, 30 parts of porous nickel, 5 parts of porous carbon, 15 parts of hollow glass microspheres, 20-30 mu m of pore diameter of the porous nickel and the porous carbon and 70% of porosity; the third layer comprises the following components in percentage by mass: 10 parts of ethylene propylene diene monomer, 40 parts of lithium titanate, 40 parts of nickel cobalt lithium manganate and 10 parts of amorphous carbon. The thicknesses of the first, second and third layers were 0.3mm, 1.0mm and 0.7mm, respectively. Ethylene propylene diene monomer is used as a base material in the first layer to the third layer.
The preparation method of the broadband wave-absorbing plate comprises the following steps:
s1, mixing treatment:
respectively and independently putting raw material particles of each layer into an internal mixer according to the mass ratio of the materials of each layer of the broadband wave absorbing plate in the embodiment, setting the temperature of the internal mixer to be 70 ℃ and the internal mixing time to be 12 hours, uniformly smelting, crushing and sieving by a 100-mesh sieve to obtain three groups of mixed materials;
s2, film forming treatment:
putting the three groups of mixed materials obtained in the step S1 into a double-roller calender with the diameter phi of 150mm and the working width of 500mm respectively, adjusting the distances among rollers to be 0.3mm, 1.0mm and 0.7mm respectively, setting the working temperature of the rollers to be 80 ℃ and the rotation linear speed to be 0.8m/min, and forming continuous films by heating and extruding through double rollers to obtain three groups of film layers;
s3, hot press forming:
and (3) sequentially laminating the three groups of film layers obtained in the step (S2) according to the sequence of the first layer, the second layer and the third layer, placing the film layers on a winding drum of a vulcanizing machine, setting the working temperature of the roller of the vulcanizing machine to be 150 ℃, setting the pressure facility between the steel belt and the roller to be 10MPa, setting the vulcanizing linear speed to be 0.6m/min, and heating and pressurizing the film layers by the vulcanizing machine for molding to obtain the broadband wave absorbing plate.
Example 4
The embodiment provides a broadband wave absorbing plate and a preparation method thereof. The broadband wave absorbing plate in the embodiment is different from the broadband wave absorbing plate in the embodiment 1 only in that "porous carbon accounts for 10 parts, hollow glass beads account for 20 parts", and "porous carbon accounts for 30 parts", the aperture of the porous carbon is 8-20 μm, and the porosity is 60%;
the preparation method of the broadband wave absorbing plate is also adjusted correspondingly.
Example 5
The embodiment provides a broadband wave absorbing plate and a preparation method thereof. The wide-band wave-absorbing plate of this embodiment has the same material types and components as those of embodiment 1, except that the wide-band wave-absorbing plate of this embodiment has a single-layer structure of multi-phase composite. The broadband wave absorbing plate of the embodiment comprises the following components in percentage by mass: 120 parts of butadiene acrylonitrile rubber, 30 parts of aluminum oxide, 30 parts of ferric oxide, 10 parts of porous carbon, 20 parts of hollow glass beads, 10 parts of butadiene acrylonitrile rubber, 50 parts of lithium titanate and 40 parts of nickel cobalt lithium manganate, wherein the pore diameter of the porous carbon and the hollow glass beads is 8-20 microns, and the porosity is 60%. The thickness of the broadband wave absorbing plate is 2.0mm. The butadiene-acrylonitrile rubber is used as a base material in the broadband wave absorbing plate.
The preparation method of the broadband wave-absorbing plate comprises the following steps:
s4, mixing treatment:
according to the mass ratio of the raw materials in the embodiment of the application, the raw materials are put into an internal mixer, the temperature of the internal mixer is set to be 80 ℃, the internal mixing time is set to be 8 hours, and after the raw materials are uniformly smelted, the raw materials are crushed and sieved by a 80-mesh screen to obtain a mixture;
s5, film forming treatment:
and (4) respectively putting the three groups of mixed materials obtained in the step (S4) into a double-roller calender with the diameter of phi 150mm and the working width of 500mm, adjusting the distance between rollers to be 2.0mm, setting the working temperature of the rollers to be 70 ℃ and the rotation linear speed to be 0.8m/min, and heating and extruding by using double rollers to form a continuous film so as to obtain the broadband wave absorbing plate.
Comparative example 1
The comparison example provides a wave absorbing plate and a preparation method, and the wave absorbing plate of the comparison example is only different from the wave absorbing plate of the example 1 in that the aperture of the porous carbon and the hollow glass bead is 2-5 μm, and the porosity is 30%.
Comparative example 2
The comparison example provides a wave absorbing plate and a preparation method, and the wave absorbing plate of the comparison example is only different from the wave absorbing plate of the example 1 in that the aperture of the contained porous carbon and hollow glass beads is 1-3 mu m, and the porosity is 20%.
Comparative example 3
The comparative example provides a wave absorbing plate and a preparation method thereof, and the wave absorbing plate of the comparative example is only different from the wave absorbing plate of the example 1 in that the pore diameter of the contained porous carbon and hollow glass beads is 30-40 mu m, and the porosity is 20%.
2. Testing the electromagnetic wave absorption effect of the broadband wave absorption plate:
the wave absorbing plates prepared in examples 1 to 5 and comparative examples 1 to 3 were tested by an arch test system built based on a vector network analyzer to obtain the reflection loss value of the wave absorbing plate at the frequency band of 1GHz to 40GHz and the corresponding frequency band, which is specifically shown in table 1 and fig. 1.
TABLE 1
It can be seen from table 1 and fig. 1 that the broadband wave-absorbing plate in example 1 has an electromagnetic wave absorption effect in the full frequency band of 1GHz to 40GHz (L to Ka band), wherein the reflection loss value is lower than-10 dB, that is, the frequency band capable of absorbing and consuming more than 90% of electromagnetic wave energy is 13.28GHz to 40GHz.
The broadband wave absorbing plate in the embodiment 2 has an electromagnetic wave absorbing effect in a frequency band of 1 GHz-40 GHz (L-Ka band) in a full frequency band, wherein a reflection loss value is lower than-10 dB, namely, the frequency band capable of absorbing and losing more than 90% of electromagnetic wave energy is 11.6 GHz-40 GHz.
In the embodiment 3, the broadband wave absorbing plate has an electromagnetic wave absorbing effect in the full frequency band of 1 GHz-40 GHz (L-Ka band), wherein the reflection loss value is lower than-10 dB, that is, the frequency band capable of absorbing and losing more than 90% of electromagnetic wave energy is 16.21 GHz-36.68 GHz.
In example 4, the second layer of the broadband wave-absorbing plate only includes porous carbon, and the broadband wave-absorbing plate has an electromagnetic wave absorption effect in the full frequency band of 1GHz to 40GHz (L to Ka band), wherein the reflection loss value is lower than-10 dB, that is, the frequency band capable of absorbing and consuming more than 90% of electromagnetic wave energy is 12.36GHz to 38.76GHz.
Example 5 the broadband wave absorbing plate is a composite multi-phase single-layer structure, and the broadband wave absorbing plate has an electromagnetic wave absorbing effect in a frequency band of 1GHz to 40GHz (L to Ka band) and a full frequency band, wherein a reflection loss value is lower than-10 dB, that is, a frequency band capable of absorbing and consuming more than 90% of electromagnetic wave energy is 10.44GHz to 30.54GHz.
Comparing the broadband wave absorbing plates in the embodiments 1 to 5 with the wave absorbing plates in the comparative examples 1 to 3, it can be seen that the broadband absorption effect of the electromagnetic waves can be realized by compounding the impedance matching wave absorbing material, the porous wave absorbing material and the resistance dielectric loss wave absorbing material, and a certain loss effect is achieved; meanwhile, the porous wave-absorbing material selects reasonable particle size and porosity, can improve the loss rate of electromagnetic wave energy, increases the frequency range of the electromagnetic wave energy with the loss of more than 90 percent, and realizes the effects of broadband absorption and strong loss of the electromagnetic wave.
Comparing the example 1 with the example 5, it can be seen that the three groups of materials contained in the broadband wave-absorbing plate are made into a three-layer structure, compared with the three groups of materials made into a multi-phase composite single-layer structure, the broadband wave-absorbing plate has higher electromagnetic wave loss rate, and the frequency range of the electromagnetic wave energy with the loss of more than 90% is larger, so that the broadband wave-absorbing and strong loss effects are more obvious.
Therefore, the broadband wave absorbing plate provided by the embodiment of the application has the effects of wide wave absorbing frequency band and high electromagnetic wave energy loss rate.
The above examples only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, and these are all within the scope of protection of the present application. Therefore, the protection scope of the present patent application shall be subject to the appended claims.
Claims (10)
1. A broadband wave-absorbing material is characterized in that: the wave-absorbing material comprises an impedance matching wave-absorbing material, a porous wave-absorbing material and a resistance dielectric loss wave-absorbing material, wherein the aperture of the porous wave-absorbing material is 5-30 mu m, and the porosity is 50-70%.
2. The broadband absorbing material of claim 1, wherein: the porous wave-absorbing material comprises at least one of porous nickel, porous carbon and hollow glass beads.
3. The broadband absorbing material of claim 1 or 2, wherein: the resistance dielectric loss wave-absorbing material comprises at least one of graphite, amorphous carbon, lithium titanate, lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminate; and/or
The attenuation coefficient of the electromagnetic wave of the resistance dielectric loss wave-absorbing material in the frequency band of 1 GHz-40 GHz is 400-800; and/or
The impedance matching wave-absorbing material comprises at least one of aluminum oxide, ferric oxide, silicon dioxide, titanium dioxide and calcium carbonate; and/or
The resistivity of the impedance matching wave-absorbing material is 10 5 Ω·m～10 6 Omega.m; and/or
The impedance matching wave-absorbing material has an impedance matching coefficient of 0.8-1 in a frequency band of 1 GHz-40 GHz.
4. The broadband absorbing material of claim 1 or 2, wherein: the mass ratio of the impedance matching wave-absorbing material to the porous wave-absorbing material to the resistance dielectric loss wave-absorbing material is (40-70): (30-50): (60-90).
5. A broadband wave absorbing plate is characterized in that: the broadband wave absorbing plate contains the broadband wave absorbing material of any one of claims 1 to 4.
6. The broadband wave absorbing plate of claim 5, wherein: the broadband wave-absorbing material comprises a first layer, a second layer and a third layer which are sequentially stacked to form a sandwich structure, wherein the material of the first layer comprises the impedance matching wave-absorbing material contained in the broadband wave-absorbing material in any one of claims 1 to 4; the material of the second layer comprises the porous wave-absorbing material contained in the broadband wave-absorbing material of any one of claims 1 to 4; the material of the third layer comprises the resistance dielectric loss wave-absorbing material contained in the broadband wave-absorbing material of any one of claims 1 to 4.
7. The broadband absorbing wave plate of claim 6, wherein: the thickness of the first layer is 0.3 mm-0.5 mm; and/or
The thickness of the second layer is 1.0 mm-1.5 mm; and/or
The thickness of the third layer is 0.5 mm-1.0 mm.
8. The broadband wave absorbing plate of claim 6 or 7, wherein: the first layer, the second layer and the third layer independently contain a base material, and
the impedance matching wave-absorbing material accounts for 40-70 wt% of the total mass of the first layer; and/or
The porous wave-absorbing material accounts for 30-50 wt% of the total mass of the second layer; and/or
The resistance dielectric loss wave-absorbing material accounts for 60-90 wt% of the total mass of the third layer.
9. The broadband wave absorbing plate of claim 8, wherein: the base material comprises at least one of nitrile rubber, styrene butadiene rubber, polyurethane rubber and ethylene propylene diene monomer rubber.
10. A preparation method of a broadband wave absorbing plate is characterized by comprising the following steps:
performing first mixing treatment on an impedance matching wave-absorbing material, a porous wave-absorbing material and a resistance dielectric loss wave-absorbing material to obtain a mixture;
carrying out first film forming treatment on the mixture to obtain a broadband wave absorbing plate;
or
Respectively carrying out second film forming treatment on the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material to obtain a first layer, a second layer and a third layer in sequence;
sequentially laminating the first layer, the second layer and the third layer to obtain a broadband wave absorbing plate;
the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material are the impedance matching wave-absorbing material, the porous wave-absorbing material and the resistance dielectric loss wave-absorbing material which are contained in the broadband wave-absorbing material of any one of claims 1 to 4.
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