Bionic icephobic surface and its laser double-beam coupling microfabrication method

Abstract

The application provides a bionic anti-icing surface and a laser double-beam coupling micro-processing method thereof, and the metal sample polished by sandpaper, ultrasonic cleaned by ethanol and deionized water is fixed on a processing platform with adjustable inclination, the surface of the metal sample placed at an inclination is ablated by a three-dimensional galvanometer, a periodic and size-controllable bionic closed inclined groove micro-nano structure is obtained, and then the surface of the metal sample is chemically treated by a hydrophobizing agent to obtain a bionic anti-icing surface. The application combines the laser double-beam coupling micro-processing method with the surface modification technology, designs and prepares a bionic micro-nano structure surface with superior dynamic anti-icing performance, the energy proportion of the double laser beams with different polarization states is changed, the parameters of the bionic closed inclined groove structure of the ablated material surface by the double laser beams are optimized, the periodic size and the microstructure shape size of the closed inclined groove structure are modulated, and the requirement of enhancing the dynamic anti-icing performance of the surface is better met.

Description

Technical Field

[0001] This application relates to the field of biomimetic anti-icing surface treatment technology, specifically to a biomimetic anti-icing surface and its laser dual-beam coupling micromachining method. Background Technology

[0002] In extremely cold and humid weather, icing and ice accumulation on metal surfaces are widespread in aerospace engineering, marine engineering, and construction, causing significant damage. Currently, active de-icing systems effectively prevent or eliminate ice accumulation. However, these systems often come with high costs and energy consumption, as well as potential environmental pollution. Passive anti-icing, with its advantages of economy, low energy consumption, and practicality, has become a research hotspot in recent years. Among these, superhydrophobic anti-icing surfaces show great potential in dynamic anti-icing performance. Specifically, the micro / nanostructure of superhydrophobic anti-icing surfaces enhances the impact deformation and rebound ability of droplets, thereby reducing the contact area and adhesion force, and significantly improving dynamic anti-icing performance. Compared with open anti-icing surfaces, closed anti-icing surfaces have better wear resistance and longer service life. The closed micro / nanostructure provides stronger support for droplets, thereby increasing the kinetic energy upon impact and achieving enhanced dynamic bounce performance. In recent years, biomimetic has had a significant impact on the fabrication of anti-icing surfaces. Initially, the microstructure of lotus leaf surfaces provided researchers with a prototype for superhydrophobic structures. This inspiration has then extended to various plants and animals, including butterfly wings, moth eye structures, pitcher plants, gecko epidermal tissue, and Arctic poppies. Researchers have continuously deepened their research in biomimetic. To obtain structurally stable and high-performance biomimetic anti-icing surfaces, researchers have conducted extensive studies. Results show that the shape, distribution, size, and processing quality of micro / nanostructures significantly affect droplet bouncing behavior. Processing quality is the decisive factor causing deviations between theoretical design and actual fabrication of anti-icing surfaces, and it has a significant impact on their dynamic anti-icing performance.

[0003] There are many methods for obtaining anti-icing surfaces, mainly including wet chemical etching, oxidation, electrodeposition, and immersion. However, these methods are limited by drawbacks such as durability, contamination, and processing efficiency, and have not yet been widely adopted. Laser ablation shows great potential in the preparation of anti-icing surfaces. It can be used to modify surface morphology and create micro / nanostructures, thereby producing anti-icing surfaces. Compared with traditional manufacturing methods, this method has several advantages, including high precision, high speed, and compatibility with various materials. Chinese patent CN113457954B discloses a system and method for laser processing of superhydrophobic surfaces. It achieves superhydrophobic processing of metal and resin material surfaces through a combination of laser irradiation and Teflon spraying. The process is relatively simple, but it is based on short-pulse single-beam laser direct writing. When processing complex closed micro / nanostructures, the thermal accumulation effect leads to repeated melting and casting during the process, resulting in the deposition of molten metal and metal oxides within the grooves, forming an uneven microstructure. Therefore, the prepared anti-icing surface deviates significantly from its expected dimensional parameters. Summary of the Invention

[0004] The main technical problem to be solved by this invention is to provide a biomimetic anti-icing surface and its laser dual-beam coupling micromachining method, which improves the controllability of micro-morphology caused by thermal accumulation effect during nanosecond laser processing, precisely controls the size and morphology of micro-nano structures, and improves the surface processing quality.

[0005] To solve the above-mentioned technical problems, the present invention provides a biomimetic anti-icing surface, comprising: a metal surface, and a biomimetic closed inclined groove structure uniformly distributed on the metal surface;

[0006] The surface of the biomimetic closed inclined groove structure is chemically treated with a hydrophobic agent; the biomimetic closed inclined groove structure includes a grid-like distribution of biomimetic closed inclined groove microstructures, and micron- or nano-sized particle structures distributed on the surface of the biomimetic closed inclined groove microstructures.

[0007] The closed inclined groove microstructure has equal length and width, the bottom depth of the inclined groove is 80-120μm, and the inclined groove inclination angle is between 15° and 60°.

[0008] On a metal surface with a closed inclined groove structure, a deionized water droplet with a volume in the μL range has a static contact angle greater than 150° and a roll-off angle less than 10°.

[0009] In a preferred embodiment: the size of the micron- or nano-sized particulate structure is 100 nm-10 μm.

[0010] This invention also provides a laser dual-beam coupling micromachining method for biomimetic anti-icing surfaces as described above, comprising the following steps:

[0011] (1) Polish the surface of the metal sample to be processed; then clean it with ethanol solution using ultrasound, then clean it with deionized water, and finally dry it with compressed air to obtain a clean metal sample.

[0012] (2) Fix the clean metal sample on the processing platform, combine two laser beams to perform three-dimensional processing on the surface of the metal sample, adjust the energy of the two laser beams by rotating the half-wave plate angle, and use the modulated and redistributed laser energy to ablate the surface of the material to be processed. By setting the laser processing parameters and laser scanning mode, a biomimetic anti-icing surface with a closed inclined groove microstructure is obtained.

[0013] (3) The metal sample with the biomimetic closed inclined groove microstructure is immersed in a hydrophobic agent for surface chemical modification, and then placed on a heating platform to dry, thus obtaining a biomimetic anti-icing surface.

[0014] In a preferred embodiment: the ultrasonic cleaning temperature in step (1) is 25-40°C and the cleaning time is 10-20 mins.

[0015] In a preferred embodiment: the two laser beams mentioned in step (2) are adjusted by a half-wave plate, an aperture and a polarizing beam splitter to obtain two laser beams, P and S, which have different polarization states and energies, and then pass through three mirrors to obtain two polarized beams, P and S, which are spatially superimposed on the corresponding positions on the surface of the metal sample by the action of the fourth mirror, the fifth mirror and the sixth mirror.

[0016] In a preferred embodiment: the laser scanning method in step (2) involves superimposing two beams on the sample surface and then using an array-style gridded cross-scanning method to ablate the surface of the sample placed on a processing platform with an adjustable tilt angle, thereby preparing a biomimetic closed-loop groove microstructure.

[0017] In a preferred embodiment: the angle of the closed inclined groove microstructure is changed by altering the tilt angle of the processing platform, thereby changing the angle of the inclined groove from 15° to 60°.

[0018] In a preferred embodiment: the intensity modulation of the two laser beams by adjusting the energy distribution of the two laser beams by the half-wave plate in step (2) is to adjust the rotation angle of the half-wave plate from 0° to 90°, and to ablate the surface of the specimen by the two laser beams, observe the surface morphology, obtain the optimal energy ratio of the two laser beams, and determine the optimal rotation angle of the half-wave plate.

[0019] In a preferred embodiment: the inter-scanning method of array-type gridding has a spacing of 20-40 μm between adjacent sidewalls of the slant slots and a scanning spacing of 10-30 μm inside the slant slots.

[0020] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0021] (1) The biomimetic closed-type inclined groove micro-nano structure prepared on the metal surface by laser dual-beam coupling micromachining method is formed on the substrate itself and then subjected to low surface energy chemical treatment, which has a better stability anti-icing structure surface compared with coating method.

[0022] (2) The laser dual-beam coupling micromachining method used in this invention to prepare biomimetic closed inclined groove structure further improves the anti-icing performance of the material surface. Compared with chemical methods and single-laser preparation methods, the processing parameters of the dual-beam laser can be changed to optimize the parameters of the biomimetic closed inclined groove micro-nano structure on the material surface ablated by the dual-beam laser, and modulate the periodic size and microstructure shape size of the closed inclined groove structure to better meet the requirements of superhydrophobicity and anti-icing performance.

[0023] (3) The laser dual-beam coupling micromachining method used in this invention to prepare closed inclined groove micro-nano structures further improves the anti-icing performance of the material surface. Compared with the use of multi-beam laser, the preparation process is simple and the method is simple to operate and low in cost to prepare a biomimetic anti-icing surface with stable surface performance.

[0024] (4) The method of the present invention is safe and reliable, does not have pollution problems, saves materials, and has high flexibility, high controllability and high precision. It can achieve anti-icing function, can be used for large-area microstructure preparation, and can also be applied to places where high-precision micro-nano structure preparation is required. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the process for preparing the biomimetic anti-icing surface with stable surface properties according to the present invention.

[0026] Figure 2 This is a schematic diagram of the laser dual-beam coupling micromachining method used in this invention;

[0027] Figure 3 This is a schematic diagram of the contact angle of the micro / nano structure surface obtained by the laser dual-beam coupling micromachining method of the present invention;

[0028] Figure 4 This is a schematic diagram of the sliding angle of the micro / nano structure surface obtained by the laser dual-beam coupling micromachining method of the present invention;

[0029] Figure 5 This is a schematic diagram of the micro-nano composite structure of the biomimetic closed inclined groove structure surface obtained by the laser dual-beam coupling micromachining method of the present invention;

[0030] Figure 6 This is a schematic diagram of the surface plan of the biomimetic closed inclined groove micro / nano structure obtained by the laser dual-beam coupling micromachining method of the present invention.

[0031] Figure 7 This is a schematic diagram illustrating the anti-icing function of the biomimetic closed-loop groove micro / nano structure surface obtained by the laser dual-beam coupling micromachining method in this invention on a low-temperature surface.

[0032] Figure 8 This is a microscopic schematic diagram of the cuticle structure of springtail and the oblique arrangement structure of pigeon feathers in this invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0036] Example 1

[0037] This embodiment provides a biomimetic anti-icing surface, characterized by comprising: a metal surface, and a biomimetic closed-loop groove structure uniformly distributed on the metal surface; the biomimetic closed-loop groove structure is obtained by combining two biological characteristics: the cuticle structure of a springtail and the oblique arrangement structure of pigeon feathers. Figure 8 ;

[0038] The surface of the biomimetic closed inclined groove structure is chemically modified with a hydrophobic agent; the biomimetic closed inclined groove structure includes a grid-like distribution of biomimetic closed inclined groove microstructures, and micron- or nano-sized particle structures distributed on the surface of the biomimetic closed inclined groove microstructures, wherein the size of the micron- or nano-sized particle structures is 100nm-10μm.

[0039] The biomimetic closed inclined groove microstructure has equal length and width, the depth of the bottom of the inclined groove is 80-120μm, and the inclination angle of the inclined groove is between 15° and 60°.

[0040] On a metal surface with a biomimetic closed-loop groove structure, a deionized water droplet with a volume in the μL range has a static contact angle greater than 150° and a roll-off angle less than 10°.

[0041] Example 2

[0042] This embodiment provides a processing method for the biomimetic anti-icing surface in Embodiment 1, using titanium alloy (TC4) material. The preparation process is as follows: Figure 1 As shown, it includes the following steps:

[0043] (1) Polish the surface of the metal sample to be treated with 600#, 1200# and 1500# SiC sandpaper respectively; then clean it with ethanol solution using ultrasonic cleaning, then clean it with deionized water, and finally dry it with compressed air to obtain a clean metal sample. It should be noted that other grit sandpaper can also be used for polishing, which is a simple substitution in this embodiment.

[0044] (2) Fix the clean metal sample on the processing platform, combine two nanosecond laser beams to perform three-dimensional processing on the metal surface, adjust the energy of the two laser beams by a half-wave plate, and use the modulated and redistributed laser energy to ablate the surface of the processed material. By setting the laser processing parameters and laser scanning mode, a biomimetic anti-icing surface with a biomimetic closed inclined groove microstructure is obtained. The laser processing parameters are: total laser power 4.36W, optimal power of the two laser beams 4.12W and 0.24W respectively, center distance of the two laser beams 40μm, wavelength 355nm, beam diameter 50μm, processing pulse frequency 50kHz, pulse duration 20ns, and scanning speed 10mm / s.

[0045] (3) A metal sample with a biomimetic closed-loop groove microstructure was immersed in a 0.1 mol / L perfluorododecyltriethoxysilane solution for surface chemical modification. The reaction temperature was 26°C and the reaction time was 6 h. After the reaction, the sample was removed and dried on a heating platform at 80°C for 20 mins to obtain a biomimetic anti-icing surface. It should be noted that this embodiment uses a perfluorododecyltriethoxysilane solution as an example. As a simple alternative, other hydrophobic agents, such as stearic acid or isopropanol solution, can also be used.

[0046] To achieve the three-dimensional machining of metal surfaces using the combination of the two nanosecond laser beams described above, this embodiment provides the following... Figure 2 The processing structure shown involves two laser beams being split into two beams by a half-wave plate (HWP), an aperture, and a polarizing beam splitter (PBS). One of these beams is then further split by a first reflecting mirror 4, a second reflecting mirror 5, and a third reflecting mirror 6. This splits the laser beam into two polarized beams, P and S, with different polarization states and energies. These two beams are then combined by a fourth reflecting mirror 7, a fifth reflecting mirror 8, and a sixth reflecting mirror 9, and then by a three-dimensional galvanometer 10, resulting in spatial superposition at corresponding positions on the specimen. The resulting dual-beam laser performs three-dimensional cross-scanning ablation on the tilted specimen surface, creating a biomimetic anti-icing surface 11. Specifically, the energy distribution of the two laser beams is modulated by rotating the half-wave plate angle. Taking vertical processing as an example, the half-wave plate angle is adjusted from 0° to 90° in 15° increments. By ablating the specimen surface with the dual laser beams and observing the surface morphology, the optimal energy ratio of the two laser beams is obtained, and the optimal rotation angle of the half-wave plate is determined. The relationship between the half-wave plate rotation angle and the delayed icing time in this embodiment is shown in the table below:

[0047] Half-wave plate rotation angle 0° 15° 30° 45° 60° 75° 90° Delayed freezing time 136s 146s 110s 106s 264s 297s 182s

[0048] It can be seen that under the experimental conditions of ambient temperature 24℃, humidity 45%, and cooling platform temperature -15℃, the best delayed icing time can be obtained when the half-wave plate is rotated 75°.

[0049] Therefore, when processing the biomimetic closed inclined groove, the half-wave plate is rotated 75°. At this time, an inclined processing method is used, and the sample is rotated step by step from an inclined angle of 15° to an inclined angle of 60° to find the optimal processing angle, as shown in the table below:

[0050] Inclination angle of the sample being processed 15° 30° 45° 60° Delayed freezing time 115s 169s 258s 171s

[0051] It can be seen that the optimal placement angle of the sample is 45°, thus obtaining the biomimetic anti-icing surface 11, including: a metal surface, and a closed inclined groove microstructure uniformly distributed on the metal surface;

[0052] The surface of the biomimetic closed inclined groove structure is chemically treated with a perfluorododecyltriethoxysilane solution; the biomimetic closed inclined groove structure includes a neatly arranged, regularly distributed grid-like closed inclined groove microstructure, and micron- or nano-sized particulate structures 12 distributed on the surface of the closed inclined groove microstructure.

[0053] The biomimetic closed inclined groove structure has a length and width equal to 200μm, a bottom depth of 90-100μm, and an inclination angle of 45°; the micron- or nano-sized particle structure 12 has a size of 100nm-10μm.

[0054] The biomimetic anti-icing surface prepared through the above steps is as follows: Figure 3 As shown, the static contact angle of 5 μL of deionized water on the surface of the closed-loop slant microstructure was measured to be 154° using a contact angle measuring instrument. Furthermore, the roll-off angle of the biomimetic closed-loop slant microstructure was measured to be 1.9°. Figure 4 As shown.

[0055] like Figure 5 As shown, the biomimetic closed-loop groove structure includes a regularly arranged grid-like distribution of biomimetic closed-loop groove microstructures, and micron- or nano-sized particle structures 12 distributed on the surface of the biomimetic closed-loop groove microstructures; on the TC4 sample substrate 14, the regularly arranged grid-like distribution of biomimetic closed-loop groove structure 13 has equal length and width, both equal to 200 μm, the depth of the bottom of the groove is 90-100 μm, the inclination angle of the groove is adjustable in the range of 15° to 60°, and the micron- or nano-sized particle structures 12 distributed on the surface of the biomimetic closed-loop groove structure have a size of 100 nm-10 μm.

[0056] like Figure 6 As shown, the TC4 biomimetic closed-loop groove microstructure surface, obtained using laser dual-beam coupling micromachining, was subjected to an array-style gridded cross-scanning method. The scanning spacing 15 inside the groove was 30 μm, and the spacing 16 between adjacent sidewalls of the grooves was 20 μm. The groove microstructure 17 had equal length and width. The first scan direction 18 was vertically downward. The second scan direction 19 was from right to left. The groove microstructure 20 had dimensions of 200 μm × 200 μm.

[0057] like Figure 7As shown, the anti-icing function of the biomimetic anti-icing TC4 surface was tested by continuously dropping water droplets from the air onto it. First, the TC4 anti-icing sample was placed on a low-temperature platform to achieve a surface temperature of -20°C. Then, a 1 mL water droplet was drawn using a syringe pump at an injection rate of 10 μL / s, resulting in a droplet volume of 9-11 μL. At a vertical height of 5 cm above the sample surface, the water droplets were continuously dropped onto the sample surface. During the droplet's fall and rebound, it deflected to the left, accelerating its detachment from the sample surface. Throughout the entire process, no ice formed on the sample surface, demonstrating that the biomimetic anti-icing TC4 surface exhibits excellent dynamic anti-icing performance.

[0058] The above description is merely a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention by those skilled in the art within the scope of the technology disclosed in the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A laser dual-beam coupling micromachining method for biomimetic anti-icing surfaces, characterized in that... The biomimetic anti-icing surface includes: a metal surface, and a biomimetic closed inclined groove structure uniformly distributed on the metal surface; The surface of the biomimetic closed inclined groove structure is chemically modified with a hydrophobic agent; the biomimetic closed inclined groove structure includes a grid-like distribution of biomimetic closed inclined groove microstructures, and micron- or nano-sized particle structures distributed on the surface of the biomimetic closed inclined groove microstructures. The biomimetic closed inclined groove microstructure has equal length and width, the depth of the bottom of the inclined groove is 80-120μm, and the inclination angle of the inclined groove is between 15° and 60°. On a metal surface with a biomimetic closed inclined groove structure, a deionized water droplet with a volume in the μL range has a static contact angle greater than 150° and a roll-off angle less than 10°. The processing method includes the following steps: (1) Polish the surface of the metal sample to be processed; then clean it with ethanol solution by ultrasonic cleaning, then clean it with deionized water, and finally dry it with compressed air to obtain a clean metal sample. (2) Fix the clean metal sample on the processing platform, combine two laser beams to perform three-dimensional processing on the surface of the metal sample, adjust the energy of the two laser beams by rotating the half-wave plate angle, and use the modulated and redistributed laser energy to ablate the metal surface to be processed. By setting the laser processing parameters and laser scanning mode, a biomimetic anti-icing surface with a biomimetic closed inclined groove microstructure is obtained. (3) The metal sample with the biomimetic closed-loop groove microstructure is immersed in a hydrophobic agent for surface chemical modification, and then dried on a heating platform to obtain a biomimetic anti-icing surface; The two laser beams mentioned in step (2) are adjusted by a half-wave plate, an aperture and a polarizing beam splitter to obtain two laser beams, P and S with different energies, and then pass through three mirrors to obtain two polarized beams with different energies. These two laser beams are spatially superimposed at corresponding positions on the surface of the metal sample by the action of the fourth mirror, the fifth mirror and the sixth mirror. A biomimetic closed-loop groove microstructure surface was obtained using a laser dual-beam coupling micromachining method. Specifically, the surface was obtained by an array-type gridded cross-scanning method. The scanning spacing inside the groove was 30 μm, and the spacing between adjacent sidewalls of the grooves was 20 μm. The biomimetic closed-loop groove microstructure had equal length and width. The first scan direction was vertically downward, and the second scan direction was from right to left. The biomimetic closed-loop groove structure had a size of 200 μm × 200 μm.

2. The laser dual-beam coupling micromachining method for biomimetic anti-icing surfaces according to claim 1, characterized in that: The micron- or nano-sized particulate structure has a size of 100 nm to 10 μm.

3. The laser dual-beam coupling micromachining method for biomimetic anti-icing surfaces according to claim 1, characterized in that, The ultrasonic cleaning temperature in step (1) is 25-40℃, and the cleaning time is 10-20 min.

4. The laser dual-beam coupling micromachining method for biomimetic anti-icing surfaces according to claim 1, characterized in that, The laser scanning method described in step (2) involves superimposing two beams on the sample surface and then using an array-type gridded cross-scanning method to ablate the surface of the sample placed on a processing platform with an adjustable tilt angle, thereby preparing a biomimetic closed-type inclined groove microstructure.

5. The laser dual-beam coupling micromachining method according to claim 4, characterized in that, The angle of the biomimetic closed inclined groove microstructure is changed by altering the tilt angle of the processing platform, thus changing the angle of the inclined groove from 15° to 60°.

6. The laser dual-beam coupling micromachining method for biomimetic anti-icing surfaces according to claim 1, characterized in that, The method described in step (2) is to adjust the energy distribution of the two laser beams by rotating the half-wave plate to modulate the intensity. This involves adjusting the rotation angle of the half-wave plate from 0° to 90°, using the two laser beams to ablate the metal surface to be processed, observing the surface morphology, obtaining the optimal energy ratio of the two laser beams, and determining the optimal rotation angle of the half-wave plate.

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