CN103317734B - Method for preparing radar wave-absorbing composite material based on carbon nanometer film - Google Patents

Abstract

A method for preparing a radar wave-absorbing composite material based on a carbon nanofilm is realized through the following steps: mixing carbon nanotubes with an anionic surface dispersant, putting the mixture into a mortar for grinding, pouring the mixture into a beaker, and adding plasma water; Pour the mixed solution into a magnetic stirrer, disperse and defoam; add graphene oxide into plasma water, prepare a solution, and disperse it ultrasonically; mix the carbon nanotube/graphene oxide solution, and then use an ultrasonic cell disruptor to ultrasonically disperse Carry out centrifugation, vacuum filter the supernatant of the carbon nanotube/graphene oxide dispersion, compact and solidify; heat treatment; put the carbon nanofilm into the acetone dilution of the resin, pre-soak and dry; layer The pre-impregnated carbon nano film is laid on the innermost layer of the aluminum alloy mold, and the carbon fiber/resin prepreg is laid in the middle, the mold is closed, and molded. The radar wave reflectivity of the radar wave-absorbing composite material of the carbon nano film prepared by the invention is less than -10dB--20dB in the frequency range of 8-18GHz.

Description

A preparation method of radar absorbing composite material based on carbon nano film

technical field

The invention relates to a method for preparing a wave-absorbing composite material, in particular to a method for preparing a radar wave-absorbing composite material based on a carbon nano-film, and belongs to the field of material science and technology.

Background technique

As an effective means to increase the survival and air defense capabilities of modern weapon systems and improve the overall combat effectiveness, radar absorbing technology has been highly valued by the world's military powers. Radar absorbing materials mainly convert incident radar waves into heat energy through electrical loss and magnetic loss. Radar absorbers are mainly golden powder and fiber represented by ferrite. Such absorbing materials have complex processing technology, high density, and poor environmental adaptability. According to reports, F117 rarely attacks in rainy days, because moisture will degrade the performance of the absorbing material.

Since the discovery of carbon nanotubes in 1991, their unique mechanical, electrical, optical and magnetic properties have attracted widespread attention from scientists around the world. Due to the small size effect, quantum size effect, and macroscopic quantum tunneling effect of carbon nanotubes, the energy level interval after the electron energy level splitting is within the microwave energy range. At the same time, carbon nanotubes have a large specific surface area and a large number of surface dangling bonds, which lead to the introduction of new absorbing mechanisms by interface polarization and multiple scattering, further enhancing their absorbing performance, and the chiral structure of carbon nanotubes is also conducive to improving its absorbing properties. These peculiar properties indicate that it has potential application value in the preparation of stealth materials. The absorbing materials prepared by compounding carbon nanotubes and polymers have become one of the important directions for the development of modern radar absorbing materials.

However, the intermolecular force of carbon nanotubes is strong, and when the amount of dispersion in the polymer matrix is large, they tend to agglomerate. At the same time, the huge specific surface area of carbon nanotubes will also increase the viscosity of the polymer matrix, making it difficult to form composite materials. , thus affecting the overall mechanical properties of the composite material, and also causing an increase in cost. Moreover, the microwave absorption of composite materials is mainly determined by the content and dispersion uniformity of carbon nanotubes. In order to obtain an effective carbon nanotube network structure, methods such as shear force stirring, three-roll stirring and ultrasonic dispersion are usually used, but resin-based The content of carbon nanotubes in the body is limited, and the prepared microwave-absorbing composite materials often cannot meet the requirements of engineering applications.

Carbon nanotube film (carbon nanopaper) is a film-like self-supporting three-dimensional structure composed of carbon nanotubes (single-walled or multi-walled) molecules connected by Van der Waals force, which has High conductivity, electromagnetic properties and mechanical properties, using it as the functional layer of radar absorbing composite materials will not affect the molding and performance of the main composite material structure. Compared with adding carbon nanotubes to the resin, the carbon nanotube film is completely Connected by carbon nanotubes, it has more excellent electrical conductivity and radar wave absorption ability.

Graphene is a new type of two-dimensional nano-carbon material composed of a layer of carbon atoms, and is currently the thinnest two-dimensional material in the world. The strength of graphene materials is the highest among known materials, and its electrical conductivity and current-carrying density are both higher than the best single-walled carbon nanotubes at present, and its excellent quantum Hall effect has also been proved. After mixing the solution of graphene oxide with carbon nanotubes, there will be a strong π-π interaction between the sidewalls of carbon nanotubes and the sheets of graphene oxide, because graphene sheets have a large number of hydrophilic functions The group will increase the dispersion effect of the graphene oxide-carbon nanotube composite in water, which is beneficial to the formation of carbon nanopaper, and will also increase the strength, electrical conductivity and electromagnetic properties of carbon nanopaper.

In addition, nickel-coated carbon nanotubes are used to prepare carbon nanotube films, and the dielectric constant and electromagnetic constant of carbon nanotube films are changed to adjust the absorption peak and frequency range of radar absorbing composite materials.

Contents of the invention

A method for preparing a radar absorbing composite material based on a carbon nanofilm is realized through the following steps:

(1) Mix carbon nanotubes and anionic surface dispersants in a ratio of 1:1-1:20, wherein commercially available multi-walled/single-walled nickel-plated carbon nanotubes are selected, with a diameter of 6-30nm and a length of 10-50 μm , the nickel content is 20-70%. Anionic surface dispersants can be selected from Triton-X100, sodium dodecylsulfonate, sodium dodecylbenzenesulfonate or a mixture of two;

(2) Put the mixture of carbon nanotubes and anionic surface dispersant into a mortar and grind for 1-60min, pour it into a beaker, add plasma water until the concentration of carbon nanotubes is 0.01-1.0wt%, and the concentration of surface dispersant is 0.01-2wt %;

(3) Pour the mixed liquid in step (2) into a magnetic stirrer, control the temperature below 60°C, disperse for 15-60min; defoam for 10-100min;

(4) Add carbon nanotubes:graphene oxide with a mass ratio of 10:1-10:3 to the plasma water, prepare a solution with a concentration of 0.1-1mg/ml, and ultrasonically disperse it for 30-60min;

(5) Mix the carbon nanotube/graphene oxide solution, and then use an ultrasonic cell disruptor to ultrasonically disperse for 10-100 minutes under the condition of 100-800w, and control the dispersion temperature within the range of 10-60°C;

(6) The carbon nanotube/graphene oxide dispersion liquid is divided into test tubes, put into the centrifuge, under the condition of rotating speed 1000-10000rpm, centrifuge for 10-80min, select the supernatant of the carbon nanotube/graphene oxide solution in the test tube liquid;

(7) select vacuum suction filtration device to prepare carbon nanofilm, permeable membrane selects the permeable membrane of millipore company, wherein this permeable membrane can be selected nylon membrane, mixed fiber membrane, thin film, aperture selects 0.22um or 0.45 μ m for use, carbon nanotube/ The supernatant of the graphene oxide dispersion is vacuum filtered, and the vacuum pump pressure is controlled within the range of 40-500Kpa, that is, the carbon nano film is prepared by vacuum filtration;

(8) After the suction filtration is completed, clean the carbon nanofilm with 1-5 times the volume of plasma water until no foam is produced;

(9) Remove the filter membrane together with the prepared carbon nano-film, put it between two stainless steel plates, compact it, put it in an oven, and cure it at 60-150°C for 2-10 hours, peel it off after curing to obtain Carbon nano film structure;

(10) Put the carbon nanofilm structure into a vacuum oven for heat treatment at 300-350°C for 30-60min, and the conductivity of the carbon nanofilm reaches 100-2000S/m;

(11) Cut the carbon nano paper according to the size of the mold, put it into the acetone diluent of the resin, pre-soak it for 24-48 hours, put it in an oven and dry it at 40 degrees for 2-4 hours, and the resin can be epoxy resin or Shuangma to imide;

(12) Lay 1-4 layers of pre-soaked carbon nano film on the innermost layer of the aluminum alloy mold, lay 8-24 layers of carbon fiber/resin prepreg in the middle, close the mold, and prepare carbon by compression molding and autoclave molding. Radar absorbing composite material of nano film, among which carbon fiber/resin prepreg can be epoxy resin/carbon fiber, bismaleimide resin/carbon fiber prepreg.

The radar wave reflectivity of the radar wave-absorbing composite material of the carbon nano film prepared by the invention is less than -10dB--20dB in the frequency range of 8-18GHz.

Description of drawings

Figure 1 Schematic diagram of the structure of radar absorbing composite materials

Detailed ways

As shown in FIG. 1 : the carbon nanofilm absorbing function layer 1 is covered on the composite material structure layer 2 .

Example 1

(1) get carbon nanotube and triton-X100 and mix by 1: 10 ratio, wherein select commercially available nickel-plated multi-wall nickel-plated carbon nanotube for use, its diameter is 8-15nm, length is 50 μ m, nickel content is 60% ;

(2) Put the mixture of carbon nanotubes and anionic surface dispersant into a mortar and grind for 40min, pour into a beaker, add plasma water until the concentration of carbon nanotubes is 0.03wt%, and the concentration of surface dispersant is 0.3wt%;

(3) Pour the mixed solution into a magnetic stirrer, control the temperature below 60°C, disperse for 60 minutes, and defoam for 40 minutes;

(4) Add graphene oxide (the mass ratio of carbon nanotubes: graphene oxide is 10:1) into plasma water, prepare a solution with a concentration of 1 mg/ml, and disperse it ultrasonically for 60 minutes;

(5) The carbon nanotube/graphene oxide dispersion liquid is divided into test tubes, and then ultrasonically disperses for 45 minutes under the condition of 540w using an ultrasonic cell disruptor, and the dispersion temperature is controlled within the range of 20-30°C;

(6) The carbon nanotube/graphene oxide dispersion liquid is divided into test tubes, put into a centrifuge, and under the condition of rotating speed 4000rpm, centrifuge for 40min, and select the supernatant of the carbon nanotube/graphene oxide solution in the test tube;

(7) Select a vacuum suction filtration device to prepare a carbon nanofilm. The permeable membrane is a mixed fiber membrane from millipore company. The pressure is controlled within the range of 300Kpa, that is, the carbon nano-film is prepared by vacuum filtration;

(8) After the suction filtration is completed, clean the carbon nanopaper with 3 times the volume of plasma water until no foam is generated;

(9) Remove the filter membrane together with the prepared carbon nanofilm, put it between two stainless steel plates, compact it, put it in an oven, and cure it at 120°C for 4 hours, peel off after curing to obtain the carbon nanofilm structure ;

(10) Put the carbon nanofilm structure into a vacuum oven for heat treatment at 300°C for 60 minutes, and the conductivity of the carbon nanofilm reaches 500S/m;

(11) Cut the carbon nano paper according to the size of the mold, put it into the acetone diluent of the resin, pre-soak it for 24 hours, put it in an oven and dry it at 40 degrees for 2 hours, and the resin can be epoxy resin or bismaleimide ;

(12) Lay 2 layers of pre-soaked carbon nano film on the innermost layer of the aluminum alloy mold, lay 16 layers of carbon fiber/epoxy prepreg in the middle, close the mold, and use autoclave molding to prepare the radar absorbing carbon nano film Composite material; the radar wave reflectivity of carbon nano film radar absorbing composite material in the frequency range of 8-18GHz is less than -8dB.

Claims (6)

1. A method for preparing a radar absorbing composite material based on carbon nanofilm is realized through the following steps: (1) Mix carbon nanotubes and anionic surface dispersant in a mass ratio of 1:1-1:20; (2) Put the mixture of carbon nanotubes and anionic surface dispersant into a mortar and grind for 1-60min, pour into a beaker, add plasma water until the concentration of carbon nanotubes is 0.01-1.0wt%, and the concentration of surface dispersant is 0.01- 2wt%; (3) Pour the mixed solution in step (2) into a magnetic stirrer, control the temperature at 20-60°C, disperse for 15-60min; defoam for 10-100min; (4) Take carbon nanotubes: graphene oxide with a mass ratio of 10:1-10:3 and add graphene oxide into plasma water, prepare a solution with a concentration of 0.1-1mg/ml, and ultrasonically disperse for 30-60min; (5) Mix the carbon nanotube/graphene oxide solution, and then use an ultrasonic cell disruptor to ultrasonically disperse for 10-100 minutes under the condition of 100-800w, and control the dispersion temperature within the range of 10-60°C; (6) The carbon nanotube/graphene oxide dispersion liquid is divided into test tubes, put into the centrifuge, under the condition of rotating speed 1000-10000rpm, centrifuge for 10-80min, select the supernatant of the carbon nanotube/graphene oxide solution in the test tube liquid; (7) Select a vacuum filtration device to prepare a carbon nanofilm, vacuum filter the supernatant of the carbon nanotube/graphene oxide dispersion, and control the vacuum pump pressure within the range of 40-500Kpa, which is prepared by vacuum filtration Carbon nano film; (8) After the suction filtration is completed, clean the carbon nanofilm with 1-5 times the volume of plasma water until no foam is produced; (9) Remove the filter membrane together with the prepared carbon nano-film, put it between two stainless steel plates, compact it, put it in an oven, and cure it at 60-150°C for 2-10 hours, peel it off after curing to obtain Carbon nano film structure; (10) Put the carbon nanofilm structure into a vacuum oven for heat treatment at 300-350°C for 30-60min, and the conductivity of the carbon nanofilm reaches 100-2000S/m; (11) Cut the carbon nano film according to the size of the mold, put it into the acetone diluent of the resin, pre-soak it for 24-48 hours, put it into an oven and dry it at 40 degrees for 2-4 hours; (12) Lay 1-4 layers of pre-soaked carbon nano film on the innermost layer of the aluminum alloy mold, lay 8-24 layers of carbon fiber/resin prepreg in the middle, close the mold, and prepare carbon by compression molding and autoclave molding. Radar absorbing composite materials of nano film. 2. a kind of radar absorbing composite material preparation method based on carbon nanofilm as claimed in claim 1, is characterized in that: described carbon nanotube is commercially available multi-wall/single-wall nickel-plated carbon nanotube, and its diameter It is 6-30nm, the length is 10-50μm, and the nickel content is 20-70%. 3. a kind of radar absorbing composite material preparation method based on carbon nano film as claimed in claim 1, is characterized in that: described anionic surface dispersant selects Triton-X100, sodium dodecylsulfonate, One or two kinds of sodium dodecylbenzenesulfonate mixed. 4. a kind of radar absorbing composite material preparation method based on carbon nano film as claimed in claim 1, is characterized in that: in step (7), when vacuum suction filter prepares carbon nano film, permeable film selects millipore company's Permeable membrane, wherein the permeable membrane is selected from nylon membrane and mixed fiber membrane, and the pore size is selected from 0.22um or 0.45μm. 5. A method for preparing a radar absorbing composite material based on a carbon nanofilm as claimed in claim 1, wherein the resin in step (11) is epoxy resin or bismaleimide. 6. a kind of radar absorbing composite material preparation method based on carbon nano film as claimed in claim 1 is characterized in that: in step (12), carbon fiber/resin prepreg is selected epoxy resin/carbon fiber or bismaleyl Imine resin/carbon fiber prepreg.