CN112191852A - Preparation method of weather-resistant electromagnetic wave absorption layer/plate - Google Patents
Preparation method of weather-resistant electromagnetic wave absorption layer/plate Download PDFInfo
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- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/14—Both compacting and sintering simultaneously
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- B22F1/102—Metallic powder coated with organic material
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- B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
- B22F7/02—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers
- B22F7/04—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers with one or more layers not made from powder, e.g. made from solid metal
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- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
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- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
- B22F7/02—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers
- B22F7/04—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers with one or more layers not made from powder, e.g. made from solid metal
- B22F2007/042—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers with one or more layers not made from powder, e.g. made from solid metal characterised by the layer forming method
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
- B22F2009/043—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by ball milling
Abstract
The invention discloses a preparation method of a weather-resistant electromagnetic wave absorption layer/plate, which comprises the following steps; dissolving a surfactant in an organic solvent, performing ultrasonic dispersion, putting magnetic electromagnetic wave absorbent powder and a dispersed surfactant solution into a ball milling tank for vacuum low-speed ball milling, and performing surface modification treatment on the absorbent; separating the ball-milled mixture from a grinding ball, centrifuging, washing, drying and grinding to obtain a modified absorbent; step three, preparing polytetrafluoroethylene suspension, coating the polytetrafluoroethylene suspension on the surface of modified absorbent powder moving in an alternating magnetic field through ultrasonic spraying to form a core-shell structure of the polytetrafluoroethylene-coated absorbent, and then drying and grinding; and step four, uniformly paving the core-shell structure powder on the surface of a workpiece to be treated or in a mold, and carrying out hot pressing on a vulcanizing machine to obtain the electromagnetic wave absorption layer/plate. The invention has the advantages of controllable thickness, strong weather resistance and the like.
Description
Technical Field
The invention belongs to the field of materials, relates to a weather-resistant anti-corrosion wave-absorbing material, and particularly relates to a preparation method of a weather-resistant electromagnetic wave absorbing layer/plate.
Background
With the coming of the 5G era and the more rigorous requirements on the application environment of materials with electromagnetic wave absorption function, the preparation of the weather-resistant and corrosion-resistant electromagnetic wave absorption hot pressing plate by coating the electromagnetic wave absorbent with magnetism with polytetrafluoroethylene is an effective way for realizing the long-term excellent electromagnetic wave absorption function in the severe working environment. At present, the requirements of protection and electromagnetic wave absorption design on workpieces or plates made by hot pressing under the environmental conditions of plateau, severe cold, strong acid and alkali corrosion, marine corrosion and the like are increasing.
In the traditional process, the electromagnetic wave absorbent powder is directly added into the matrix and then mechanically mixed to manufacture the coating and the plate, and the method has the problems of absorbent sedimentation, poor compatibility, poor wettability, poor dispersibility and the like in the matrix.
Disclosure of Invention
The invention provides a preparation method of a weather-resistant electromagnetic wave absorption layer/plate, which overcomes the defects of the prior art.
To achieve the above object, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, having the following features: comprises the following steps;
dissolving a surfactant in an organic solvent, performing ultrasonic dispersion, putting magnetic electromagnetic wave absorbent powder and the dispersed surfactant solution into a ball milling tank, performing vacuum low-speed ball milling, and performing surface modification treatment on the absorbent.
And step two, separating the ball-milled mixture from the grinding balls, centrifuging, washing, drying and grinding to obtain the modified absorbent.
And step three, preparing polytetrafluoroethylene suspension, coating the polytetrafluoroethylene suspension on the surface of the modified absorbent powder moving in the alternating magnetic field through ultrasonic spraying to form a core-shell structure of the polytetrafluoroethylene-coated absorbent, and then drying and grinding. Specifically, the magnetic surface-modified electromagnetic wave absorbent powder becomes charged particles on a power-on flat plate, the particles move in a space under the action of an alternating magnetic field, ultrasonic spraying is matched, and a spray head sprays and coats polytetrafluoroethylene suspension on the surface of the absorbent powder moving in the space, so that the polytetrafluoroethylene is uniformly coated on the surface of the absorbent.
And step four, uniformly paving the core-shell structure powder on the surface of a workpiece to be treated or in a mold, and carrying out hot pressing on a vulcanizing machine to finally obtain the electromagnetic wave absorption layer/plate.
Further, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, which may further have the following characteristics: in the first step, the magnetic electromagnetic wave absorbent is carbonyl iron, ferroferric oxide, ferrite, nickel powder or metal-organic framework Materials (MOFs).
Further, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, which may further have the following characteristics: wherein, in the step one, the size of the electromagnetic wave absorbent powder with magnetism is 1-20 μm.
Further, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, which may further have the following characteristics: in the first step, the surfactant is silane coupling agent or polyvinylpyrrolidone, and the surfactant solution is prepared by dissolving 3-10mL of silane coupling agent or 0.1-1g of polyvinylpyrrolidone in each 60mL of organic solvent; the organic solvent comprises methanol, ethanol, ethyl propanol, acetone, benzene, toluene, xylene, etc.; the adding ratio of the absorbent to the surfactant solution is 40 g: 60 mL.
Further, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, which may further have the following characteristics: wherein, in the first step, the ball milling time is 1h, the rotating speed of the low-speed ball milling is 100-150r/min, and the ball-material ratio is 15: 1; the ball milling tank is made of stainless steel, agate or polytetrafluoroethylene and can be vacuumized; the grinding balls are made of stainless steel, agate or zirconia.
Further, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, which may further have the following characteristics: in the third step, the mass fraction of the polytetrafluoroethylene suspension is 20-80%; the mass ratio of the modified absorbent to the polytetrafluoroethylene suspension is 1: 2-10: 1.
Further, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, which may further have the following characteristics: wherein, in the third step, the obtained core-shell structure is ground after being dried for 8-24h at 60 ℃.
Further, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, which may further have the following characteristics: and in the fourth step, powder is paved according to the thickness of the electromagnetic wave absorption layer/plate to be obtained, and the powder paving and hot pressing are repeated once when the thickness exceeds 10 mm.
Further, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, which may further have the following characteristics: wherein, in the fourth step, the temperature is set to 250 ℃ and 330 ℃ in the hot pressing process, and the temperature is kept for 1-6 h.
Further, the present invention provides a method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet, which may further have the following characteristics: and in the fourth step, the workpiece is made of aluminum alloy, titanium alloy, copper alloy, steel or composite material, and the surface of the workpiece is polished to be rough before powder spreading and hot pressing.
The invention has the beneficial effects that: the invention provides a preparation method of a weather-resistant electromagnetic wave absorption layer/plate, which is characterized in that electromagnetic wave absorbent powder with magnetic surface modification moves in space through an alternating magnetic field, and polytetrafluoroethylene suspension is sprayed and coated on the surface of the electromagnetic wave absorbent powder with magnetic surface modification through an ultrasonic spraying method. After preparing the polytetrafluoroethylene-coated electromagnetic wave absorbent powder, directly hot-pressing and molding on a vulcanizing machine by controlling the thickness of the paved powder to obtain the weather-resistant electromagnetic wave absorbing plate with controllable thickness, or hot-pressing after polishing the surface of a workpiece to be rough and regulating the thickness of the paved powder to form a weather-resistant electromagnetic wave absorbing layer on the surface of the workpiece.
The problems of sedimentation caused by high density of the absorbent, poor compatibility, wettability, dispersibility and the like in the liquid matrix, and the problems of poor compatibility, wettability, dispersibility and the like in the liquid matrix in the traditional process (the coating and the plate are prepared by directly adding electromagnetic wave absorbent powder into the liquid matrix and then mechanically mixing and curing the absorbent powder) are solved and avoided, the electromagnetic wave absorbing layer/plate with certain mechanical property and excellent weather resistance is obtained, the service of the plate/workpiece under the environmental conditions of plateau, high cold, strong acid and alkali corrosion, marine corrosion and the like can be greatly improved, and the long-acting electromagnetic wave absorbing function is realized. Specifically, the electromagnetic wave absorption layer/plate is formed by directly hot-pressing solid powder, so that the problem of sedimentation cannot occur; meanwhile, the absorbent and the polytetrafluoroethylene are firstly coated into an integral core-shell structure and then are uniformly laid, so that the absorbent and the polytetrafluoroethylene (matrix) have good compatibility and dispersibility; in addition, the polytetrafluoroethylene with stable performance is wrapped outside the adsorbent, so that the weather resistance of the adsorbent can be directly improved.
The polytetrafluoroethylene suspension is coated on the surface of the magnetic electromagnetic wave absorbent by a magnetic suspension ultrasonic spraying method, so that the weather resistance of the absorbent is directly improved, the method is high in yield, the step treatment is not complicated, the process is simple, and the yield is high. After the electromagnetic wave absorbing agent with weather resistance is prepared, the powder is directly paved on the surface of a workpiece or a plate for hot pressing, so that the problems of poor compatibility, non-wetting, uneven distribution and the like of polytetrafluoroethylene in a matrix can be solved, the problem of sedimentation of the absorbing agent in the matrix can be solved, and meanwhile, the plate prepared by the preparation method of the weather-resistant electromagnetic wave absorbing layer/plate also has certain mechanical property and wide application prospect.
Drawings
FIG. 1 is a scanning electron microscope image of carbonyl iron powder, which is an electromagnetic wave absorbent having magnetism and is obtained by modifying the surfactant obtained in the second step of example 1;
FIG. 2 is a scanning electron microscope image of a core-shell structure formed of a polytetrafluoroethylene-coated carbonyl iron powder obtained in step three of example 1;
FIG. 3 is a surface elemental analysis chart of a core-shell structure formed of a polytetrafluoroethylene-coated carbonyl iron powder obtained in step three of example 1;
fig. 4 is a wave-absorbing performance diagram of the electromagnetic wave absorbing sheet obtained in example 2.
Detailed Description
The present invention is further illustrated by the following specific examples.
Example 1
The embodiment provides a method for preparing a weather-resistant electromagnetic wave absorption layer, which comprises the following steps;
step one, dissolving 5mL of a surfactant silane coupling agent in 60mL of ethyl alcohol for ultrasonic dispersion, putting 40g (the particle size of carbonyl iron powder is 5 microns) of magnetic electromagnetic wave absorbent powder carbonyl iron powder and a dispersed surfactant solution into a 500mL stainless steel ball milling tank, grinding balls made of stainless steel in a ball-material ratio of 15: 1, ball milling for 1 hour at a vacuum rotation speed of 100r/min, and carrying out surface modification treatment on an absorbent.
And step two, separating the ball-milled mixture from the milling balls, centrifuging, washing, drying and grinding to obtain about 30g of modified absorbent. The appearance of the magnetic electromagnetic wave absorbent carbonyl iron powder modified by the surfactant under a scanning electron microscope is shown in figure 1.
And step three, preparing polytetrafluoroethylene suspension with the mass fraction of 40%. The electromagnetic wave absorbent powder with magnetic surface modification becomes charged particles on a power-on flat plate, moves in a space with the action of an alternating magnetic field, and is matched with ultrasonic spraying, and a spray head sprays and coats polytetrafluoroethylene suspension on the surface of the modified absorbent powder moving in the space to form a core-shell structure of polytetrafluoroethylene-coated modified absorbent, so that the polytetrafluoroethylene is uniformly coated on the surface of the absorbent. Wherein the mass ratio of the modified absorbent to the polytetrafluoroethylene suspension is 1: 2.
Drying the core-shell structure at 60 ℃ for 8h, grinding, and obtaining powder particles with the morphology shown in figure 2 under a scanning electron microscope, wherein the surface element analysis is shown in figure 3, and the elemental analysis shows that the main element on the surface is C, F, Fe, which indicates that the polytetrafluoroethylene forms the core-shell structure on the surface of the carbonyl iron powder.
And step four, uniformly paving the core-shell structure powder on the surface of a polished titanium alloy workpiece to be treated, paving the powder at a height of 3mm, carrying out hot pressing on the surface of the polished titanium alloy workpiece on a vulcanizing machine, setting the temperature at 300 ℃, and carrying out heat preservation for 1h to finally obtain an electromagnetic wave absorption layer with excellent weather resistance and thickness of 2mm, wherein the effective absorption bandwidth (reflection loss < -10dB) of electromagnetic waves reaches 7.47 GHz.
Example 2
The embodiment provides a method for preparing a weather-resistant electromagnetic wave absorption plate, comprising the following steps;
step one, dissolving 0.8g of polyvinylpyrrolidone serving as a surfactant in 60mL of ethanol for ultrasonic dispersion, putting 40g (the grain diameter of carbonyl iron powder is 15 microns) of carbonyl iron powder serving as magnetic electromagnetic wave absorbent powder and the dispersed surfactant solution into a 500mL agate ball milling tank, grinding the materials of agates to obtain balls, wherein the ball-material ratio is 15: 1, and carrying out ball milling for 1 hour at the vacuum rotation speed of 100r/min to carry out surface modification treatment on the absorbent.
And step two, separating the ball-milled mixture from the milling balls, centrifuging, washing, drying and grinding to obtain about 30g of modified absorbent.
And step three, preparing polytetrafluoroethylene suspension with the mass fraction of 60%. The electromagnetic wave absorbent powder with magnetic surface modification becomes charged particles on a power-on flat plate, moves in a space with the action of an alternating magnetic field, and is matched with ultrasonic spraying, and a spray head sprays and coats polytetrafluoroethylene suspension on the surface of the modified absorbent powder moving in the space to form a core-shell structure of polytetrafluoroethylene-coated modified absorbent, so that the polytetrafluoroethylene is uniformly coated on the surface of the absorbent. Wherein the mass ratio of the modified absorbent to the polytetrafluoroethylene suspension is 5: 1.
Drying the core-shell structure at 60 ℃ for 8h, and grinding to obtain core-shell structure powder of the polytetrafluoroethylene-coated modified absorbent.
And step four, uniformly paving the core-shell structure powder in a mold, paving the powder with the height of 1.5mm, carrying out hot pressing on a vulcanizing machine, setting the temperature at 280 ℃, and carrying out heat preservation for 1.5 hours to finally obtain the electromagnetic wave absorbing plate with the thickness of 1.3mm, excellent weather resistance and certain mechanical property, and carrying out wave absorbing performance test on the electromagnetic wave absorbing plate, wherein the result is shown in figure 4, the effective bandwidth reaches 8.12GHz, and the requirements of the electromagnetic wave absorbing material on thinness, strength, lightness and width are met.
Example 3
The embodiment provides a method for preparing a weather-resistant electromagnetic wave absorption plate, comprising the following steps;
step one, dissolving 1g of polyvinylpyrrolidone serving as a surfactant in 60mL of methanol for ultrasonic dispersion, putting 40g (the particle size of carbonyl iron powder is 10 microns) of magnetic electromagnetic wave absorbent powder carbonyl iron powder and a dispersed surfactant solution into a 500mL stainless steel ball milling tank, grinding balls made of stainless steel in a ball-material ratio of 15: 1, ball milling for 1 hour at a vacuum rotation speed of 100r/min, and carrying out surface modification treatment on the absorbent.
And step two, separating the ball-milled mixture from the milling balls, centrifuging, washing, drying and grinding to obtain about 30g of modified absorbent.
And step three, preparing polytetrafluoroethylene suspension with the mass fraction of 60%. The electromagnetic wave absorbent powder with magnetic surface modification becomes charged particles on a power-on flat plate, moves in a space with the action of an alternating magnetic field, and is matched with ultrasonic spraying, and a spray head sprays and coats polytetrafluoroethylene suspension on the surface of the modified absorbent powder moving in the space to form a core-shell structure of polytetrafluoroethylene-coated modified absorbent, so that the polytetrafluoroethylene is uniformly coated on the surface of the absorbent. Wherein the mass ratio of the modified absorbent to the polytetrafluoroethylene suspension is 10: 1.
Drying the core-shell structure at 60 ℃ for 8h, and grinding to obtain core-shell structure powder of the polytetrafluoroethylene-coated modified absorbent.
And step four, uniformly paving the core-shell structure powder in a mold, uniformly paving the powder according to the required thickness, wherein the thickness of the electromagnetic wave absorption plate to be obtained is about 15mm, uniformly paving the powder according to the required thickness, the powder is 10mm high for the first time, the temperature is set to be 300 ℃ on a vulcanizing machine, the heat is preserved for 2h, the thickness of the electromagnetic wave absorption plate obtained after hot pressing is 9.5mm, the powder is uniformly paved on the electromagnetic wave absorption plate for 6mm high, then hot pressing is carried out on the vulcanizing machine, the temperature is set to be 300 ℃, the heat is preserved for 3h, and finally the electromagnetic wave absorption plate with the excellent weather resistance and certain mechanical property is obtained, wherein the effective absorption bandwidth (reflection loss < -10dB) of the electromagnetic wave reaches 11.12.
Example 4
The embodiment provides a method for preparing a weather-resistant electromagnetic wave absorption layer, which comprises the following steps;
step one, dissolving 5mL of a surfactant silane coupling agent in 60mL of toluene for ultrasonic dispersion, putting 40g of magnetic electromagnetic wave absorbent powder ferroferric oxide (the particle size of the ferroferric oxide is 3 mu m) and dispersed surfactant solution into a 500mL stainless steel ball milling tank, grinding balls made of stainless steel, the ball-material ratio of the balls is 15: 1, and carrying out ball milling for 1 hour at the vacuum rotation speed of 120r/min, and carrying out surface modification treatment on an absorbent.
And step two, separating the ball-milled mixture from the milling balls, centrifuging, washing, drying and grinding to obtain about 30g of modified absorbent.
And step three, preparing polytetrafluoroethylene suspension with the mass fraction of 80%. The electromagnetic wave absorbent powder with magnetic surface modification becomes charged particles on a power-on flat plate, moves in a space with the action of an alternating magnetic field, and is matched with ultrasonic spraying, and a spray head sprays and coats polytetrafluoroethylene suspension on the surface of the modified absorbent powder moving in the space to form a core-shell structure of polytetrafluoroethylene-coated modified absorbent, so that the polytetrafluoroethylene is uniformly coated on the surface of the absorbent. Wherein the mass ratio of the modified absorbent to the polytetrafluoroethylene suspension is 1: 2.
Drying the core-shell structure at 60 ℃ for 8h, and grinding to obtain core-shell structure powder of the polytetrafluoroethylene-coated modified absorbent.
And step four, uniformly paving the core-shell structure powder on the surface of a polished steel workpiece to be treated, uniformly paving the powder according to the required thickness, wherein the powder paving height is 6mm, carrying out hot pressing on a vulcanizing machine, setting the temperature at 310 ℃, and carrying out heat preservation for 2.5h to finally obtain the electromagnetic wave absorption layer with the thickness of 5mm and excellent weather resistance, wherein the effective absorption bandwidth (reflection loss < -10dB) of the electromagnetic wave reaches 6.33 GHz.
Example 5
The embodiment provides a method for preparing a weather-resistant electromagnetic wave absorption layer, which comprises the following steps;
step one, dissolving 0.5g of polyvinylpyrrolidone serving as a surfactant in 60mL of ethanol for ultrasonic dispersion, putting 40g of ferroferric oxide (with the particle size of 5 microns) serving as magnetic electromagnetic wave absorbent powder and the dispersed surfactant solution into a 500mL agate ball milling tank, grinding the materials of the agate into agate, wherein the ball-material ratio is 15: 1, and carrying out ball milling for 1 hour at the vacuum rotation speed of 120r/min, thereby carrying out surface modification treatment on the absorbent.
And step two, separating the ball-milled mixture from the milling balls, centrifuging, washing, drying and grinding to obtain about 30g of modified absorbent.
And step three, preparing polytetrafluoroethylene suspension with the mass fraction of 50%. The electromagnetic wave absorbent powder with magnetic surface modification becomes charged particles on a power-on flat plate, moves in a space with the action of an alternating magnetic field, and is matched with ultrasonic spraying, and a spray head sprays and coats polytetrafluoroethylene suspension on the surface of the modified absorbent powder moving in the space to form a core-shell structure of polytetrafluoroethylene-coated modified absorbent, so that the polytetrafluoroethylene is uniformly coated on the surface of the absorbent. Wherein the mass ratio of the modified absorbent to the polytetrafluoroethylene suspension is 3: 1.
Drying the core-shell structure at 60 ℃ for 8h, and grinding to obtain core-shell structure powder of the polytetrafluoroethylene-coated modified absorbent.
And step four, uniformly paving the core-shell structure powder on the surface of a polished copper alloy workpiece to be treated, uniformly paving the powder according to the required thickness, wherein the powder paving height is 2mm, carrying out hot pressing on a vulcanizing machine, setting the temperature at 260 ℃, and carrying out heat preservation for 1h to finally obtain the electromagnetic wave absorption layer with the thickness of 1.3mm and excellent weather resistance, wherein the effective absorption bandwidth (reflection loss < -10dB) of the electromagnetic wave reaches 6.56 GHz.
Example 6
This example provides a method for preparing a weather-resistant electromagnetic wave absorbing layer, which comprises the following steps: in the first step, the magnetic electromagnetic wave absorbent powder is ferrite, in the fourth step, the workpiece is a carbon fiber composite plate, the temperature is set to be 260 ℃, and the effective absorption bandwidth (reflection loss < -10dB) of electromagnetic waves reaches 6.17 GHz.
Example 7
This example provides a method for preparing a weather-resistant electromagnetic wave absorbing sheet, which comprises the following steps: in the first step, the magnetic electromagnetic wave absorbent powder is ferrite, and the effective absorption bandwidth (reflection loss < -10dB) of the electromagnetic wave reaches 6.65 GHz.
Example 8
This example provides a method for preparing a weather-resistant electromagnetic wave absorbing layer, which comprises the following steps: in the first step, the magnetic electromagnetic wave absorbent powder is MoF, the grain diameter is 8 mu m, the ball milling tank is made of polyvinyl chloride, and the effective absorption bandwidth (reflection loss < -10dB) of the electromagnetic wave reaches 4.62 GHz.
Example 9
This example provides a method for preparing a weather-resistant electromagnetic wave absorbing sheet, which comprises the following steps: in the first step, the magnetic electromagnetic wave absorbent powder is MoF, the particle size is 1 mu m, the ball milling pot is made of agate, and the effective absorption bandwidth (reflection loss < -10dB) of electromagnetic waves reaches 5.33 GHz.
Claims (10)
1. A method for preparing a weather-resistant electromagnetic wave absorption layer/plate is characterized by comprising the following steps:
comprises the following steps;
dissolving a surfactant in an organic solvent, performing ultrasonic dispersion, putting magnetic electromagnetic wave absorbent powder and a dispersed surfactant solution into a ball milling tank for vacuum low-speed ball milling, and performing surface modification treatment on the absorbent;
separating the ball-milled mixture from a grinding ball, centrifuging, washing, drying and grinding to obtain a modified absorbent;
step three, preparing polytetrafluoroethylene suspension, coating the polytetrafluoroethylene suspension on the surface of modified absorbent powder moving in an alternating magnetic field through ultrasonic spraying to form a core-shell structure of the polytetrafluoroethylene-coated absorbent, and then drying and grinding;
and step four, uniformly paving the core-shell structure powder on the surface of a workpiece to be treated or in a mold, and carrying out hot pressing on a vulcanizing machine to finally obtain the electromagnetic wave absorption layer/plate.
2. The method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet as claimed in claim 1, wherein:
in the first step, the magnetic electromagnetic wave absorbent is carbonyl iron, ferroferric oxide, ferrite, nickel powder or a metal-organic framework material.
3. The method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet as claimed in claim 1, wherein:
wherein, in the step one, the size of the electromagnetic wave absorbent powder with magnetism is 1-20 μm.
4. The method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet as claimed in claim 1, wherein:
in the first step, the surfactant is silane coupling agent or polyvinylpyrrolidone, and the surfactant solution is prepared by dissolving 3-10mL of silane coupling agent or 0.1-1g of polyvinylpyrrolidone in each 60mL of organic solvent;
the adding ratio of the absorbent to the surfactant solution is 40 g: 60 mL.
5. The method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet as claimed in claim 1, wherein:
wherein, in the first step, the ball milling time is 1h, the rotating speed of the low-speed ball milling is 100-150r/min, and the ball-material ratio is 15: 1;
the ball milling tank is made of stainless steel, agate or polytetrafluoroethylene and can be vacuumized;
the grinding balls are made of stainless steel, agate or zirconia.
6. The method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet as claimed in claim 1, wherein:
in the third step, the mass fraction of the polytetrafluoroethylene suspension is 20-80%;
the mass ratio of the modified absorbent to the polytetrafluoroethylene suspension is 1: 2-10: 1.
7. The method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet as claimed in claim 1, wherein:
wherein, in the third step, the obtained core-shell structure is ground after being dried for 8-24h at 60 ℃.
8. The method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet as claimed in claim 1, wherein:
and in the fourth step, powder is paved according to the thickness of the electromagnetic wave absorption layer/plate to be obtained, and the powder paving and hot pressing are repeated once when the thickness exceeds 10 mm.
9. The method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet as claimed in claim 1, wherein:
wherein, in the fourth step, the temperature is set to 250 ℃ and 330 ℃ in the hot pressing process, and the temperature is kept for 1-6 h.
10. The method for preparing a weather-resistant electromagnetic wave absorbing layer/sheet as claimed in claim 1, wherein:
and in the fourth step, the workpiece is made of aluminum alloy, titanium alloy, copper alloy, steel or composite material, and the surface of the workpiece is polished to be rough before powder spreading and hot pressing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010958365.0A CN112191852B (en) | 2020-09-14 | 2020-09-14 | Preparation method of weather-resistant electromagnetic wave absorption layer/plate |
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