A method for preparing an integrated wave-absorbing surface based on ultrafast laser processing
An integrated microwave absorbing surface was prepared on a metal substrate by using ultrafast laser processing technology. A magnetic nanostructure was formed in a liquid environment using a femtosecond laser, which solved the problem of weak bonding of the microwave absorbing coating and improved the microwave absorption performance and bonding strength.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING INST OF TECH
- Filing Date
- 2025-03-07
- Publication Date
- 2026-06-26
AI Technical Summary
The existing absorbing coating has weak bonding strength with the substrate material, which affects the absorbing performance.
Using ultrafast laser processing technology, an integrated microwave absorbing surface is prepared on the surface of a metal substrate. The precursor solution and the metal substrate are simultaneously modified by femtosecond laser in a liquid environment to form a magnetic nanostructure, which enhances the bonding strength and microwave absorption performance.
While ensuring the mechanical properties of the substrate, the bonding strength and absorption performance of the absorbing material are significantly improved, and the magnetic loss resistance to electromagnetic waves is enhanced.
Smart Images
Figure CN120249950B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microwave absorbing material coating technology, specifically relating to an integrated microwave absorbing surface preparation method based on ultrafast laser processing. Background Technology
[0002] With the rapid development of science and 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 weapons but also has a significant impact on precision instruments, such as causing malfunctions and leaks of classified information, thus affecting national security. Furthermore, electromagnetic radiation is also harmful to the human body; long-term exposure to high-radiation environments can 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 of suppressing and reducing electromagnetic radiation.
[0003] Electromagnetic absorbing materials are materials that allow electromagnetic waves to be incident on the material surface through impedance matching, causing them to penetrate into the material's interior. The electromagnetic waves are then attenuated by the material's dielectric and magnetic losses. Currently, the common practice is to coat a substrate surface with absorbing materials to reduce the harmful effects of electromagnetic radiation. However, the absorbing layer coated on the substrate surface can easily affect the mechanical properties of the substrate surface, and the adhesion is not strong enough, making it prone to detachment and failure, thus affecting the substrate surface's absorbing performance. Summary of the Invention
[0004] Based on the above analysis, the present invention aims to provide an integrated microwave absorbing surface preparation method based on ultrafast laser processing, in order to solve the problem that the bonding strength between the microwave absorbing coating and the substrate material is not strong enough, thus affecting the microwave absorbing performance.
[0005] A method for preparing an integrated microwave absorbing surface based on ultrafast laser processing includes:
[0006] S1: Remove the oxide layer from the surface of the metal substrate;
[0007] S2: Preparation of precursor solution;
[0008] S3: Place the metal substrate in the precursor solution and irradiate the interface between the metal substrate and the precursor solution with a spatially shaped femtosecond laser perpendicularly.
[0009] S4: Synchronously move the precursor solution and the metal substrate, and use a femtosecond laser to reduce the precursor and load it onto the surface of the metal substrate;
[0010] The precursor solution comprises a suspension of metal oxide nanoparticles and a metal salt solution, wherein 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 0.01-1M;
[0012] 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 metal substrate is made of an alloy material, preferably an aluminum alloy or a titanium alloy.
[0014] Furthermore, S2 includes:
[0015] S201: Dilute the high-concentration metal oxide nanoparticle suspension with deionized water and sonicate 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 homogeneous metal salt solution;
[0017] S203: Mix the diluted metal oxide nanoparticle suspension with the metal salt solution in a certain proportion, stir thoroughly, and then sonicate for about 10-20 minutes until the mixed solution reaches a uniform and stable state.
[0018] Furthermore, the high-concentration metal oxide nanoparticles have a mass fraction of 20%, and the diluted mass fraction is 0.1%.
[0019] Furthermore, the concentration of the metal salt solution is 0.1M.
[0020] Furthermore, in step S3, the metal substrate is placed in a culture dish, and a precursor solution is added 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.
[0021] Furthermore, in step S4, the position of the culture dish is adjusted by moving a displacement stage, and the displacement stage moves at a speed of 0.1-1 mm / s; preferably, the displacement stage moves at a speed of 0.5 mm / s.
[0022] Furthermore, the path spacing is adjusted according to the width of the femtosecond laser ablation path to achieve an overlap rate of 50%.
[0023] Furthermore, the parameters of the femtosecond laser and the optical path transmission system used to control the femtosecond laser are as follows: the repetition frequency of the femtosecond laser is 1000Hz; the attenuator in the optical path transmission system is adjusted so that the output power at the end of the optical path is 800-1200mW; preferably, the output power at the end of the optical path is 900mW.
[0024] A metallic microwave absorbing material, wherein the metallic microwave absorbing material is prepared by any one of the above-described integrated microwave absorbing surface preparation methods based on ultrafast laser processing.
[0025] Compared with existing technologies, this invention modifies the surface layer of a metal substrate using ultrafast lasers in a liquid-phase environment, uniformly loading magnetic nanostructure components onto the metal substrate. This enhances the magnetic loss of the metal substrate to microwaves, improves its absorption performance, and strengthens the bond between the absorption layer and the metal substrate. Thus, through femtosecond laser irradiation, the reduction of the precursor solution and the modification of the microstructure on the metal substrate surface are simultaneously achieved, effectively improving the absorption performance while maintaining the original mechanical properties of the metal substrate. This provides a method for improving microwave absorption performance by introducing metals of different compositions onto the surface of a metal substrate.
[0026] This invention achieves the fabrication of an integrated microwave absorbing surface by employing an ultrafast laser processing method, which greatly enhances the microwave absorption capability of the substrate surface while improving the bonding strength. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the processing optical path of an integrated microwave absorbing surface preparation method based on ultrafast laser processing according to the present invention;
[0028] Figure 2 This is a graph showing the reflectivity test results for the infrared band in an embodiment of the present invention. Detailed Implementation
[0029] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and, together with the embodiments of the present invention, serve to illustrate the principles of the invention, but are not intended to limit the scope of the invention. To further explain the technical solutions of the present invention, detailed descriptions will be provided below with reference to the embodiments.
[0030] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.
[0031] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.
[0032] To overcome the problems that the absorption layer coated on the substrate surface can easily affect the mechanical properties of the substrate surface and is not firmly bonded, making it prone to peeling and failure, thus affecting the microwave absorption performance of the substrate surface, this invention provides an integrated microwave absorption surface preparation method based on ultrafast laser processing. When preparing the microwave absorption coating, femtosecond laser micro-nano processing technology is used to modify the surface, thereby improving the microwave absorption performance and achieving a tight bond between the absorption layer and the metal substrate surface without affecting the surface mechanical properties.
[0033] Specifically, the method includes the following steps:
[0034] S1: Remove the oxide layer from the surface of the metal substrate;
[0035] S2: Preparation of precursor solution;
[0036] S3: Place the metal substrate in the precursor solution and irradiate the interface between the metal substrate and the precursor solution with a spatially shaped femtosecond laser perpendicularly.
[0037] S4: Synchronously move the precursor solution and the metal substrate, and use a femtosecond laser to reduce the precursor and load it onto the surface of the metal substrate;
[0038] The precursor solution includes a suspension of metal oxide nanoparticles and a metal salt solution, wherein 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] 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 existing technologies, this invention uses a spatially shaped femtosecond laser to process and modify a metal substrate in a liquid precursor environment. This allows the ultrafast laser to modify the surface of the metal substrate while simultaneously reducing the liquid precursor. This ensures that the surface mechanical properties are not compromised, and effectively creates a tightly bonded magnetic nanostructure layer on the metal surface. This improves the magnetic loss of the metal surface to microwaves and enhances its microwave absorption performance.
[0042] Specifically, in S1, the metal substrate is made of an alloy material, such as aluminum alloy, titanium alloy, etc. For example, the metal substrate is made of aluminum alloy.
[0043] Among these processes, the surface of the metal substrate is treated with sandblasting and polishing to remove contaminants and oxide films, keeping the surface of the metal substrate smooth and flat, and reducing the impact on subsequent processing.
[0044] Specifically, in S2, the precursor solution is a solution containing microwave-absorbing metal components. For example, the metal oxide particles are selected from Fe2O3; for example, 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 sonicate for 10-20 minutes to make the diluted suspension reach a stable state of uniform dispersion.
[0047] The high concentration of metal oxide nanoparticles has a mass fraction of 20%, and the mass fraction after dilution is 0.04-0.1%, preferably 0.1%, so that the nanostructure can easily nucleate.
[0048] S202: Dissolve the metal salt in deionized water to prepare a homogeneous metal salt solution;
[0049] The concentration of the metal salt solution is 0.01-1M, preferably 0.1M.
[0050] S203: Mix the diluted metal oxide nanoparticle suspension with the metal salt solution in a certain proportion, stir thoroughly, and then sonicate for about 10-20 minutes until the mixed solution reaches a uniform and stable state.
[0051] The volume ratio of the metal oxide nanoparticle suspension to the metal salt solution is 3:2.
[0052] Specifically, in S3, the metal substrate is placed in a petri dish, and a precursor solution is added so that the liquid level is 2-5 mm higher than the surface of the metal substrate. For example, the liquid level of the precursor solution is 3 mm higher than the surface of the metal substrate.
[0053] Among them, femtosecond laser processing methods include spatial shaping, which refers to using optical devices such as cylindrical mirrors and objective lenses to shape the shape and energy distribution of the femtosecond laser beam so that the energy reaches above the ablation threshold of the material. This can effectively process the precursor solution and the surface of the metal substrate simultaneously, thereby modifying the metal substrate.
[0054] Specifically, in S4, the position of the culture dish is adjusted by moving the stage, thereby adjusting the position of the precursor solution and the metal substrate; wherein, the moving speed of the stage is 0.1-1 mm / s, for example, the moving speed is 0.5 mm / s.
[0055] The path spacing is adjusted according to the width of the femtosecond laser ablation path to achieve an overlap rate of 50%.
[0056] The parameters of the femtosecond laser and the optical path transmission system used to control the femtosecond laser are as follows: the repetition frequency of the femtosecond laser is 1000Hz; the attenuator in the optical path transmission system is adjusted so that the output power at the end of the optical path is 800-1200mW, for example, the output power at the end of the optical path is 900mW.
[0057] Furthermore, after the metal substrate is processed, ultrasonic cleaning is performed to remove the precursor solution from the surface.
[0058] Compared with existing technologies, this invention modifies the surface layer of a metal substrate using ultrafast lasers in a liquid-phase environment, uniformly loading magnetic nanostructure components onto the metal substrate. This enhances the magnetic loss of the metal substrate to microwaves, improving its absorption performance and the bonding strength between the absorption layer and the metal substrate. Thus, through femtosecond laser irradiation, the reduction of the precursor solution and the modification of the microstructure on the metal substrate surface are simultaneously achieved, effectively improving the microwave absorption performance while maintaining the original mechanical properties of the metal substrate. This provides a method for improving microwave absorption performance by introducing metals of different compositions onto the surface of a metal substrate.
[0059] The femtosecond laser liquid phase ablation process mainly involves two parts: the interaction between the femtosecond laser and the solution, and the interaction between the femtosecond laser and the metal substrate. In the femtosecond laser-solution interaction stage, the interaction between the laser and water induces plasma generation. Within this plasma, a high concentration of solvated electrons is generated. These electrons can reduce metal ions and oxides in the solution, thereby producing nanoparticles. The presence of larger oxide particles facilitates nucleation and growth. Due to gravity, some nanoparticles deposit on the surface of the metal substrate. When the femtosecond laser interacts with the metal substrate, micro / nano structures with strong adhesion to the substrate are formed based on the previously deposited nanoparticles.
[0060] This invention utilizes femtosecond lasers to process materials in a liquid-phase environment, creating micro / nano structures on the material surface. This unique structure allows incident electromagnetic waves to undergo multiple reflections within the material, with the reflected waves interfering and canceling each other out, thereby enhancing the material's absorption capacity for electromagnetic waves. Furthermore, this invention selects magnetic metals such as Fe, Co, Ni, and Mn as precursors for liquid-phase processing. This transforms the originally non-magnetic metal surface into a magnetic micro / nano structure, significantly improving its magnetic loss resistance to electromagnetic waves and further enhancing the material's wave absorption performance.
[0061] Example 1
[0062] A method for preparing an integrated microwave absorbing surface based on ultrafast laser processing includes:
[0063] S1: Pre-treatment such as sandblasting and polishing is performed on the surface of the aluminum alloy substrate to remove surface contaminants and oxide film, so that the surface is as smooth and flat as possible, and to reduce the impact on subsequent processing.
[0064] S2: Preparation of precursor solution, including:
[0065] S201: Take 50 μL of a 20% iron oxide nanoparticle suspension, add 6 ml of deionized water, and sonicate for 15 minutes to achieve uniform dispersion of the suspension.
[0066] S202: Weigh 0.238g of nickel chloride hexahydrate powder and 0.238g of cobalt chloride hexahydrate powder, pour them into a volumetric flask and dissolve them in deionized water. The final solution volume is 4ml. Stir thoroughly to completely dissolve the powder.
[0067] S203: Mix the prepared suspension with the salt solution, stir thoroughly, and then sonicate for about 20 minutes to make the precursor solution reach a uniform and stable state.
[0068] S3: Place the metal substrate in the precursor solution and irradiate the interface between the metal substrate and the precursor solution with a spatially shaped femtosecond laser perpendicularly.
[0069] In this process, the metal substrate is placed in a petri dish, and a precursor solution is added so that the liquid level is 3 mm above the surface of the aluminum alloy substrate.
[0070] Among them, spatial shaping involves using optical devices such as cylindrical mirrors and objective lenses to shape the shape and energy distribution of the femtosecond laser beam, so that the energy reaches above the ablation threshold of the material. This can effectively process the precursor solution and the surface of the aluminum alloy substrate simultaneously, thereby modifying the aluminum alloy substrate.
[0071] S4: Synchronously move the precursor solution and the metal substrate, and use a femtosecond laser to reduce the precursor and load it onto the surface of the metal substrate;
[0072] In this process, the prepared surface dish is placed in a femtosecond laser processing system. The optical path system in the processing system allows the femtosecond laser to be perpendicularly irradiated onto the surface to be processed. After the laser beam is shaped, the processing is performed on the surface of the metal substrate.
[0073] The femtosecond laser processing system includes a femtosecond laser, an optical path transmission system, a spatial shaping system, a displacement stage, etc.
[0074] The parameters of the femtosecond laser and the optical path transmission system used to control the femtosecond laser are as follows: the repetition frequency of the femtosecond laser is 1000Hz; the attenuator in the optical path transmission system is adjusted so that the output power at the end of the optical path is 900mW.
[0075] Among them, the spatial shaping system is used to shape the shape and energy distribution of femtosecond laser beams;
[0076] The position of the culture dish was adjusted by moving a displacement stage at a speed of 0.5 mm / s. The path spacing was adjusted according to the width of the femtosecond laser ablation path to achieve an overlap rate of 50%.
[0077] Furthermore, the processed aluminum alloy is removed and subjected to ultrasonic cleaning for 5-10 minutes to remove the precursor solution from the surface.
[0078] The following examples are prepared using methods similar to those in Example 1:
[0079]
[0080]
[0081] The microwave absorbing materials obtained in Examples 1-8 and Comparative Examples 1-3 were tested:
[0082] 1. For example Figure 2 As shown, the infrared absorption capability of the integrated absorbing surface after ultrafast laser processing was tested and compared using an infrared microscope. It can be seen that the nanostructure generated by femtosecond laser liquid phase ablation is uniformly formed and coated on the surface of the metal substrate, which improves the absorption performance.
[0083] Comparative Example 2 shows the aluminum alloy surface after only polishing pretreatment.
[0084] like Figure 2 As shown in the figure, from top to bottom on the right side, the test results of the absorbing materials prepared 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 are presented.
[0085] 2. Test the absorption force of the absorbing materials obtained in Examples 1-8 and Comparative Examples 1-3:
[0086] Method for measuring attraction force: The permanent magnet material is magnetized by a magnetizer with a magnetic moment of 1.0 mm on one side and multi-pole magnetization. The rubber magnetic sheet is magnetized and the surface magnetic field of the rubber magnet after magnetization is 100 Gs. The magnetized rubber magnet is adsorbed onto the products obtained in Examples 1-8 and Comparative Examples 1-3. The vertical tensile force is measured by a tensile gauge and the vertical tensile force data is obtained.
[0087] The test results are shown in Table 1:
[0088] Testing items Examples 1-8 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Suction force g / cm 2 > >10 >10 \ 4.7
[0089] As can be seen, the bonding strength between the absorbing layer of the absorbing material 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 preferred embodiments of the present invention, used to explain the present invention, but not to limit the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.
Claims
1. A method for preparing an integrated microwave absorbing surface based on ultrafast laser processing, characterized in that, include: S1: Remove the oxide layer from the surface of the metal substrate; S2: Preparation of precursor solution; S3: Place the metal substrate in the precursor solution and irradiate the interface between the metal substrate and the precursor solution with a spatially shaped femtosecond laser perpendicularly. S4: Synchronously move the precursor solution and the metal substrate, and use a femtosecond laser to reduce the precursor and load it onto the surface of the metal substrate; The precursor solution comprises a suspension of metal oxide nanoparticles and a metal salt solution, wherein the volume ratio of the suspension of metal oxide nanoparticles 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; 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. The metal substrate is made of aluminum alloy or titanium alloy; The parameters of the femtosecond laser and optical transmission system used to control the femtosecond laser are as follows: the repetition frequency of the femtosecond laser is 1000Hz; the attenuator in the optical transmission system is adjusted so that the output power at the end of the optical path is 800-1200 mW.
2. The method according to claim 1, characterized in that: S2 includes: S201: Dilute the high-concentration metal oxide nanoparticle suspension with deionized water and sonicate 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 homogeneous metal salt solution; S203: Mix the diluted metal oxide nanoparticle suspension with the metal salt solution in a certain proportion, stir thoroughly, and then sonicate for 10-20 minutes until the mixed solution reaches a uniform and stable state.
3. The method according to claim 2, characterized in that: The high-concentration metal oxide nanoparticles have a mass fraction of 20%, and the diluted mass fraction is 0.1%.
4. The method according to claim 2, characterized in that: The concentration of the metal salt solution is 0.1 M.
5. The method according to claim 1, characterized in that: In step S3, the metal substrate is placed in a culture dish, and a precursor solution is added so that the liquid level is 2-5 mm above the surface of the metal substrate.
6. The method according to claim 5, characterized in that: In S3, 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, characterized in that: In step S4, the position of the culture dish is adjusted by moving a displacement stage, with the displacement stage moving at a speed of 0.1-1 mm / s.
8. The method according to claim 7, characterized in that: In S4, the displacement stage moves at a speed of 0.5 mm / s.
9. The method according to claim 8, characterized in that: The path spacing is adjusted according to the width of the femtosecond laser ablation path to achieve an overlap rate of 50%.
10. The method according to claim 9, characterized in that: The output power at the end of the optical path is 900mW.
11. A metallic microwave absorbing material, characterized in that, The metal absorbing material is prepared using the integrated absorbing surface preparation method based on ultrafast laser processing as described in any one of claims 1-10.