Integrated wave-absorbing surface preparation method based on ultrafast laser processing

Abstract

The invention belongs to the technical field of wave-absorbing material coatings, and particularly relates to an integrated wave-absorbing surface preparation method based on ultrafast laser processing, which realizes integrated preparation of a nano wave-absorbing material by introducing an ultrafast laser micro-nano processing technology. According to the method, the metal substrate is processed and modified in the liquid precursor environment by using the space shaping femtosecond laser, so that the surface of the metal substrate is processed and modified while the liquid precursor is reduced by the ultrafast laser, and the surface of the metal substrate can be improved under the condition that the mechanical property of the surface is not lost. According to the invention, a magnetic nano-structure layer which is tightly combined is effectively generated on the metal surface, so that the magnetic loss of the metal surface to microwaves is improved, the wave-absorbing performance is improved, and the problem that the wave-absorbing performance is influenced due to the fact that an existing wave-absorbing coating is not firmly combined with a substrate is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave absorbing material coatings, and particularly relates to a method for preparing an integrated microwave absorbing surface based on ultrafast laser processing. Background Art

[0002] With the rapid development of technology and the electronics industry, electronic devices have become indispensable in daily life. However, while these devices bring great convenience, they also cause serious electromagnetic radiation problems. Electromagnetic radiation not only threatens the use of traditional combat weapons but also has a significant impact on precision instruments, such as causing abnormal operation of the instruments and leakage of confidential information, thus affecting national security. In addition, electromagnetic radiation is also harmful to the human body. Long-term exposure to a high-radiation environment may cause permanent damage to the central nervous system. Therefore, using electromagnetic wave protection materials to absorb and block the propagation of harmful electromagnetic waves has become one of the effective means to suppress and reduce electromagnetic radiation.

[0003] Microwave absorbing materials are a type of materials that can make electromagnetic waves enter the material surface through impedance matching, enter the interior of the material, and attenuate the electromagnetic waves through dielectric loss and magnetic loss inside the material. Currently, generally, a microwave absorbing material is coated on the surface of a substrate to reduce the harm of electromagnetic radiation. However, the absorption layer coated on the substrate surface easily affects the mechanical properties of the substrate surface, and the bonding is not firm enough, easily falling off and failing, thus affecting the microwave absorbing performance of the substrate surface. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a method for preparing an integrated microwave absorbing surface based on ultrafast laser processing to solve the problem that the bonding strength between the microwave absorbing coating and the substrate material is not firm, which affects the microwave absorbing performance.

[0005] A method for preparing an integrated microwave absorbing surface based on ultrafast laser processing includes:

[0006] S1: Removing the oxide layer on the surface of the metal substrate;

[0007] S2: Preparing a precursor solution;

[0008] S3: Placing the metal substrate in the precursor solution and vertically irradiating the interface between the metal substrate and the precursor solution with femtosecond laser after spatial shaping;

[0009] S4: Synchronously moving the precursor solution and the metal substrate, and using the femtosecond laser to reduce the precursor and load it on the surface of the metal substrate;

[0010] Wherein, the precursor solution includes a suspension of metal oxide nanoparticles and a metal salt solution, and the volume ratio of the suspension of metal oxide nanoparticles to the metal salt solution is 3:2;

[0011] The mass fraction of the metal oxide nanoparticles is 0.04 - 0.1%, and the concentration of the metal salt solution is 0.01 - 1 M;

[0012] Among them, the metal oxide is selected from one or two of Fe2O3 and NiO; the metal salt is selected from one or more of FeCl3, CoCl2, NiCl2, and MnCl2.

[0013] Furthermore, the material of the metal substrate is an alloy material, preferably aluminum alloy or titanium alloy.

[0014] Furthermore, the S2 includes:

[0015] S201: Dilute the high-concentration metal oxide nanoparticle suspension with deionized water and perform ultrasonic oscillation for 10 - 20 minutes to make the diluted suspension reach a stable state of uniform dispersion;

[0016] S202: Dissolve the metal salt in deionized water to prepare a uniform metal salt solution;

[0017] S203: Mix the diluted metal oxide nanoparticle suspension and the metal salt solution in proportion, fully stir, and then perform ultrasonic oscillation for about 10 - 20 minutes until the mixed solution reaches a uniform and stable state.

[0018] Furthermore, the mass fraction of the high-concentration metal oxide nanoparticles is 20%, and the mass fraction after dilution is 0.1%.

[0019] Furthermore, the concentration of the metal salt solution is 0.1 M.

[0020] Furthermore, in the S3, place the metal substrate in a petri dish and add the precursor solution so that the height of the liquid surface is 2 - 5 mm higher than the surface of the metal substrate; preferably, the height of the liquid surface of the precursor solution is 3 mm higher than the surface of the metal substrate.

[0021] Furthermore, in the S4, use a displacement stage to move and adjust the position of the petri dish, and the moving speed of the displacement stage is 0.1 - 1 mm / s; preferably, the moving speed of the displacement stage is 0.5 mm / s.

[0022] Furthermore, adjust the path spacing according to the width of the femtosecond laser ablation path so that the overlap rate is 50%.

[0023] Furthermore, the parameters of the femtosecond laser and the optical path transmission system for controlling the femtosecond laser are: the repetition frequency of the femtosecond laser is 1000 Hz; adjust the attenuation sheet in the optical path transmission system to make the output power at the end of the optical path be 800 - 1200 mW; preferably, the output power at the end of the optical path is 900 mW.

[0024] A metal wave-absorbing material, which is prepared by using the integrated wave-absorbing surface preparation method based on ultrafast laser processing described in any one of the above.

[0025] Compared with the prior art, in the present invention, the surface layer part of the metal substrate is subjected to ultrafast laser modification in a liquid phase environment, so that the magnetic nanostructure components are uniformly loaded onto the metal substrate, enhancing the magnetic loss of the metal substrate to microwaves, improving the wave-absorbing performance and the bonding strength between the absorption layer and the metal substrate. Thus, through the irradiation of femtosecond laser, the reduction of the precursor solution and the modification of the microstructure on the surface of the metal substrate are realized synchronously, and the wave-absorbing performance is effectively improved while ensuring the mechanical properties of the original metal substrate. A method for improving the wave-absorbing performance by introducing metals with different components on the surface of the metal substrate is provided.

[0026] In the present invention, by adopting the method of ultrafast laser processing, the preparation of the integrated wave-absorbing surface is realized, and while improving the bonding force, the wave-absorbing ability of the substrate surface is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the processing optical path of an integrated wave-absorbing surface preparation method based on ultrafast laser processing of the present invention;

[0028] Figure 2 is a test result diagram of the reflectivity for the infrared band in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following will specifically describe the preferred embodiments of the present invention in conjunction with the drawings, wherein the drawings form a part of this application and are used together with the embodiments of the present invention to explain the principle of the present invention, and are not used to limit the scope of the present invention. In order to further explain the technical solution of the present invention, the following will be elaborated in detail in conjunction with the embodiments.

[0030] The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels without special instructions;

[0031] The experimental methods in the following embodiments are all conventional methods without special instructions.

[0032] In order to overcome the problem that the absorption layer coated on the surface of the substrate is likely to affect the mechanical properties of the substrate surface, and the bonding is not firm enough, it is easy to fall off and fail, thereby affecting the wave-absorbing performance of the substrate surface, the present invention provides an integrated wave-absorbing surface preparation method based on ultrafast laser processing, and uses femtosecond laser micro-nano processing technology for surface modification when preparing the wave-absorbing coating, realizing the improvement of the wave-absorbing performance and the tight bonding between the absorption layer and the surface of the metal substrate without affecting the surface mechanical properties.

[0033] Specifically, the method includes the steps of:

[0034] S1: Remove the oxide layer on the surface of the metal substrate;

[0035] S2: Prepare a precursor solution;

[0036] S3: Place the metal substrate in the precursor solution, and make the femtosecond laser after spatial shaping vertically irradiate at the interface of the metal substrate and the precursor solution;

[0037] S4: Synchronously move the precursor solution and the metal substrate, and use the femtosecond laser to reduce the precursor and load it on the surface of the metal substrate;

[0038] Among them, the precursor solution includes a suspension of metal oxide nanoparticles and a metal salt solution. Among them, the volume ratio of the suspension of metal oxide nanoparticles to the metal salt solution is 3:2;

[0039] The mass fraction of the metal oxide nanoparticles is 0.04 - 0.1%, and the concentration of the metal salt solution is 0.01 - 1M;

[0040] Among them, the metal oxide is selected from one or two of Fe2O3 and NiO; the metal salt is selected from one or more of FeCl3, CoCl2, NiCl2, and MnCl2.

[0041] Compared with the prior art, the present invention processes and modifies the metal substrate in a liquid precursor environment by using spatially shaped femtosecond laser, so that while the ultrafast laser reduces the liquid precursor, it processes and modifies the surface of the metal substrate, which can ensure that the surface mechanical properties are not lost, and effectively generates a magnetically - containing nanostructure layer with tight bonding on the metal surface, thereby enhancing the magnetic loss of the metal surface to microwaves and improving the wave - absorbing performance.

[0042] Specifically, in S1, the material of the metal substrate is an alloy material, such as alloy materials like aluminum alloy and titanium alloy. Exemplarily, the material of the metal substrate is aluminum alloy.

[0043] Among them, the surface of the metal substrate is sand - blasted, polished and other treatments to remove the pollutants and oxide film on the surface of the metal substrate, so that the surface of the metal substrate remains smooth and flat, reducing the influence on subsequent processing.

[0044] Specifically, in S2, the precursor solution is a solution containing wave - absorbing metal components. Exemplarily, the metal oxide particles are selected from Fe2O3; Exemplarily, the metal salt is selected from nickel chloride hexahydrate.

[0045] Specifically, S2 includes:

[0046] S201: Dilute the high-concentration metal oxide nanoparticle suspension with deionized water and perform ultrasonic oscillation for 10 - 20 minutes to make the diluted suspension reach a stable state of uniform dispersion;

[0047] Among them, the mass fraction of the high-concentration metal oxide nanoparticles is 20%, and the mass fraction after dilution is 0.04 - 0.1%, preferably 0.1%, so as to facilitate the nucleation of the nanostructures.

[0048] S202: Dissolve the metal salt in deionized water to prepare a uniform metal salt solution;

[0049] Among them, the concentration of the metal salt solution is 0.01 - 1 M, preferably 0.1 M.

[0050] S203: Mix the diluted metal oxide nanoparticle suspension and the metal salt solution in proportion, fully stir and then perform ultrasonic oscillation for about 10 - 20 minutes until the mixed solution reaches a uniform and stable state;

[0051] Among them, the volume ratio of the metal oxide nanoparticle suspension to the metal salt solution is 3:2.

[0052] Specifically, in S3, place the metal substrate in a petri dish and add the precursor solution so that the liquid level is 2 - 5 mm higher than the surface of the metal substrate. Exemplarily, the liquid level of the precursor solution is 3 mm higher than the surface of the metal substrate.

[0053] Among them, the femtosecond laser processing method includes spatial shaping, which means using optical devices such as cylindrical lenses and objective lenses to shape the beam shape and energy distribution of the femtosecond laser, so that the energy reaches above the ablation threshold of the material, and can effectively synchronously process the precursor solution and the surface of the metal substrate to achieve the modification of the metal substrate.

[0054] Specifically, in S4, use the displacement stage to move and adjust the position of the petri dish, thereby adjusting the positions of the precursor solution and the metal substrate; among them, the moving speed of the displacement stage is 0.1 - 1 mm / s. Exemplarily, the moving speed is 0.5 mm / s.

[0055] Among them, adjust the path spacing according to the width of the femtosecond laser ablation path so that the overlap rate is 50%.

[0056] Among them, the parameters of the femtosecond laser and the optical path transmission system for controlling the femtosecond laser are: the repetition frequency of the femtosecond laser is 1000 Hz; adjust the attenuation sheet in the optical path transmission system to make the output power at the end of the optical path be 800 - 1200 mW. Exemplarily, the output power at the end of the optical path is 900 mW.

[0057] Further, after the metal substrate processing is completed, perform ultrasonic cleaning to remove the precursor solution on the surface.

[0058] Compared with the prior art, in the present invention, the surface part of the metal substrate is subjected to ultrafast laser modification in a liquid phase environment, so that the magnetic nanostructure components are uniformly loaded onto the metal substrate, enhancing the magnetic loss of the metal substrate to microwaves, improving the wave absorption performance and the bonding strength between the absorption layer and the metal substrate. Thus, through the irradiation of femtosecond laser, the reduction of the precursor solution and the modification of the microstructure on the surface of the metal substrate are realized synchronously, and the wave absorption performance is effectively improved while ensuring the mechanical properties of the original metal substrate. A method for improving the wave absorption performance by introducing metals with different components on the surface of the metal substrate is provided.

[0059] In the femtosecond laser liquid phase ablation process, it mainly includes two parts: the interaction between the femtosecond laser and the solution, and the interaction between the femtosecond laser and the metal substrate. In the stage of the interaction between the femtosecond laser and the solution, the interaction between the laser and water will induce the generation of plasma. In this plasma, a high concentration of solvated electrons will be generated, and these electrons can reduce metal ions, oxides, etc. in the solution, thereby generating nanoparticles. The presence of larger particle oxides will promote the occurrence of nucleation and growth more easily. Due to the influence of gravity, some nanoparticles will deposit on the surface of the metal substrate. When the femtosecond laser interacts with the metal substrate, based on the nanoparticles deposited on the substrate surface before, a micro-nano structure with a strong bonding force with the substrate will be formed.

[0060] In the present invention, the material is processed by femtosecond laser in a liquid phase environment, so that a micro-nano structure is formed on the surface of the material. This special structure can make the incident electromagnetic wave reflect multiple times inside it, and the reflected waves interfere with each other and cancel each other out, thereby enhancing the absorption ability of the material to the electromagnetic wave. In addition, the present invention selects magnetic metals such as Fe, Co, Ni, Mn, etc. as the precursors for liquid phase processing. A magnetic micro-nano structure is generated on the surface of the original non-magnetic metal, which greatly improves the magnetic loss ability to electromagnetic waves and further enhances the wave absorption performance on the surface of the material.

[0061] Example 1

[0062] A method for preparing an integrated wave-absorbing surface based on ultrafast laser processing includes:

[0063] S1: Perform pretreatment such as sandblasting and polishing on the surface of the aluminum alloy substrate to remove surface contaminants and oxide films, and keep the surface as smooth and flat as possible to reduce the influence on subsequent processing;

[0064] S2: Prepare a precursor solution, including:

[0065] S201: Take 50 μL of an iron oxide nanoparticle suspension with a mass fraction of 20%, add 6 ml of deionized water, and perform ultrasonic oscillation for 15 minutes to make the suspension reach a uniformly dispersed state;

[0066] S202: Weigh 0.238 g of nickel chloride hexahydrate powder and 0.238 g of cobalt chloride hexahydrate powder, pour them into a volumetric flask and dissolve them in deionized water. The final volume of the solution is 4 ml, and stir well to completely dissolve the powder;

[0067] S203: Mix the above-prepared suspension with the salt solution, stir well, and then perform ultrasonic oscillation for about 20 minutes to make the precursor solution reach a uniformly stable state.

[0068] S3: Place the metal substrate in the precursor solution, and make the femtosecond laser after spatial shaping perpendicularly irradiate at the interface between the metal substrate and the precursor solution;

[0069] Among them, place the metal substrate in a petri dish, add the precursor solution, and make the liquid level 3 mm higher than the surface of the aluminum alloy substrate.

[0070] Among them, spatial shaping includes using optical devices such as cylindrical lenses and objective lenses to shape the beam shape and energy distribution of the femtosecond laser, so that the energy reaches above the ablation threshold of the material, and can effectively synchronously process the precursor solution and the surface of the aluminum alloy substrate to achieve the modification of the aluminum alloy substrate.

[0071] S4: Synchronously move the precursor solution and the metal substrate, and use the femtosecond laser to reduce the precursor and deposit it on the surface of the metal substrate;

[0072] Among them, place the prepared petri dish in the femtosecond laser processing system. The optical path system in the processing system can make the femtosecond laser perpendicularly irradiate the surface to be processed. After shaping the laser beam, processing is carried out on the surface of the metal substrate;

[0073] Among them, the femtosecond laser processing system includes a femtosecond laser, an optical path transmission system, a spatial shaping system, a displacement stage, etc.;

[0074] Among them, the parameters of the femtosecond laser and the optical path transmission system for controlling the femtosecond laser are: the repetition frequency of the femtosecond laser is 1000 Hz; adjust the attenuation sheet in the optical path transmission system to make the output power at the end of the optical path 900 mW;

[0075] Among them, the spatial shaping system is used to shape the beam shape and energy distribution of the femtosecond laser;

[0076] Among them, use the displacement stage to move and adjust the position of the petri dish. The moving speed of the displacement stage is 0.5 mm / s, and adjust the path spacing according to the width of the femtosecond laser ablation path to make the overlap rate 50%;

[0077] Further, the processed aluminum alloy is taken out and ultrasonically cleaned for 5 - 10 minutes to remove the precursor solution on the surface.

[0078] The preparation methods of the following examples are similar to that of Example 1:

[0079]

[0080]

[0081] The wave - absorbing materials obtained in Examples 1 - 8 and Comparative Examples 1 - 3 are detected:

[0082] 1. As Figure 2 shown, the wave - absorbing ability test of the integrated wave - absorbing surface after ultrafast laser processing in the infrared band is carried out using an infrared microscope. It can be seen that the nanostructures generated by femtosecond laser liquid - phase ablation are uniformly formed and coated on the metal substrate surface, improving the wave - absorbing performance.

[0083] Among them, Comparative Example 2 is the surface of the aluminum alloy after only polishing pretreatment.

[0084] As Figure 2 shown in, from top to bottom at the right end of the figure are the detection results of the wave - absorbing materials prepared by using Comparative Example 2, Comparative Example 1, Comparative Example 3, Example 7, Example 8, Example 4, Example 5, Example 6, Example 2, Example 3, and Example 1.

[0085] 2. Test the suction force of the wave - absorbing materials obtained in Examples 1 - 8 and Comparative Examples 1 - 3:

[0086] Method for measuring the suction force: The permanent magnetic material is magnetized unidirectionally and multipolarly with a magnetic moment of 1.0 mm by a magnetizer to magnetize the rubber magnetic sheet. After magnetization, the surface magnetic field of the rubber magnet is 100 Gs. The magnetized rubber magnet is adsorbed on the products obtained in Examples 1 - 8 and Comparative Examples 1 - 3, and a tensiometer is used to detect its vertical pulling force to obtain the vertical pulling force data.

[0087] The detection results are shown in Table 1:

[0088] Test Items Examples 1 - 8 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Suction force g / cm 2 > >10 >10 \ 4.7

[0089] It can be seen that the bonding strength between the absorption layer of the wave - absorbing materials obtained in Examples 1 - 8 and the metal substrate is significantly improved, ensuring the mechanical properties of the original metal substrate.

[0090] The above are the preferred embodiments of the present invention, which are used to explain the present invention rather than limit the present invention. Any changes made according to the technical solution of the present invention, when the functional effects produced do not exceed the scope of the technical solution of the present invention, all belong to the protection scope of the present invention.

Claims

1. An integrated preparation method of an electromagnetic wave absorbing surface based on ultrafast laser processing, characterized in that, Including: S1: Remove the oxide layer on the surface of the metal substrate; S2: Prepare the precursor solution; S3: Place the metal substrate in the precursor solution, and make the femtosecond laser after spatial shaping vertically irradiate at the interface of the metal substrate and the precursor solution; S4: Synchronously move the precursor solution and the metal substrate, and use the femtosecond laser to reduce the precursor and load it on the surface of the metal substrate; Wherein, the precursor solution includes a metal oxide nanoparticle suspension and a metal salt solution, and the volume ratio of the metal oxide nanoparticle suspension to the metal salt solution is 3:2; The mass fraction of the metal oxide nanoparticles is 0.04 - 0.1%, and the concentration of the metal salt solution is 0.01 - 1M; Wherein, the metal oxide is selected from one or two of Fe2O3 and NiO; the metal salt is selected from one or more of FeCl3, CoCl2, NiCl2, and MnCl2.

2. The method according to claim 1, wherein: The material of the metal substrate is an alloy material, preferably aluminum alloy or titanium alloy.

3. The method according to claim 1, wherein: The S2 includes: S201: Dilute the high-concentration metal oxide nanoparticle suspension with deionized water, and perform ultrasonic oscillation for 10 - 20 minutes to make the diluted suspension reach a stable state of uniform dispersion; S202: Dissolve the metal salt in deionized water to prepare a uniform metal salt solution; S203: Mix the diluted metal oxide nanoparticle suspension and the metal salt solution in proportion, fully stir, and then perform ultrasonic oscillation for about 10 - 20 minutes until the mixed solution reaches a uniform and stable state.

4. The method according to claim 3, wherein: The mass fraction of the high-concentration metal oxide nanoparticles is 20%, and the mass fraction after dilution is 0.1%.

5. The method according to claim 3, characterized in that: The concentration of the metal salt solution is 0.1M.

6. The method according to claim 1, characterized in that: In the S3, place the metal substrate in a petri dish, add the precursor solution, so that the liquid level is 2 - 5 mm higher than the surface of the metal substrate; preferably, the liquid level of the precursor solution is 3 mm higher than the surface of the metal substrate.

7. The method according to claim 6, wherein: In the S4, use a displacement stage to move and adjust the position of the petri dish, and the moving speed of the displacement stage is 0.1 - 1 mm / s; preferably, the moving speed of the displacement stage is 0.5 mm / s.

8. The method according to claim 7, characterized in that: Adjust the path spacing according to the width of the femtosecond laser ablation path so that the overlap rate is 50%.

9. The method according to claim 8, wherein: The parameters of the femtosecond laser and the optical path transmission system for controlling the femtosecond laser are: the repetition frequency of the femtosecond laser is 1000 Hz; adjust the attenuation sheet in the optical path transmission system to make the output power at the end of the optical path be 800 - 1200 mW; preferably, the output power at the end of the optical path is 900 mW.

10. A metal wave-absorbing material, characterized in that, The metal absorbing material is prepared by the integrated absorbing surface preparation method based on ultrafast laser processing described in any one of claims 1 - 9.

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