A method and processing device for preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic dual cavitation coupling

Abstract

The present invention provides a method and processing device for preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic dual cavitation coupling, wherein the two ends of the aluminum alloy plate to be processed are installed at the bottom of the cavitation bin so that the upper surface of the aluminum alloy plate to be processed is immersed in the medium in the cavitation bin; a pulsed laser beam is focused in the medium in the cavitation bin to generate a laser cavitation zone; ultrasonic vibration is applied to the lower surface of the aluminum alloy plate to be processed, and an ultrasonic cavitation zone is generated below the laser cavitation zone. The fluid power generated by the collapse of the laser-induced cavitation bubble collapses on the upper surface of the aluminum alloy plate to be processed, and the shock wave and microjet generated by the collapse act on the upper surface of the aluminum alloy plate to be processed to form a micron-level porous structure; the upper surface of the aluminum alloy plate to be processed after cavitation is chemically modified to reduce the surface energy of the material to form a super-hydrophobic surface. The present invention enables the specimen to produce a super-hydrophobic surface while generating a symmetrical stress distribution in the thickness direction, and the performance of the aluminum alloy is enhanced and high flatness is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of surface modification, and in particular to a method and a processing device for preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic dual cavitation coupling. Background Art

[0002] Aviation aluminum alloys, with their high specific strength and low specific gravity, possess excellent mechanical and processing properties, making them widely used in aircraft skins, frames, and other components. However, due to their high surface wettability, they are susceptible to icing under high-temperature, low-humidity conditions. This can increase aircraft weight and flight resistance, severely impacting performance. Therefore, improving the hydrophobic and anti-icing properties of aluminum alloy surfaces is of great significance in the aviation field.

[0003] Currently, the processing methods for achieving superhydrophobic properties on material surfaces include electrochemical method, electric spark micromachining method, chemical etching method, electroplating method, sol-gel method, etc. However, these preparation methods have many inherent defects, such as complex process, low efficiency, harsh preparation environment, and poor mechanical stability of the prepared micron-level porous structure. Therefore, it is particularly important to find a suitable superhydrophobic surface preparation process.

[0004] Cavitation occurs when a liquid rapidly evaporates into gas, forming bubbles, due to a decrease in external pressure or an increase in temperature. Cavitation can be divided into two categories based on how it occurs: energy deposition-induced cavitation and cavitation pressure drop-induced cavitation. Both lasers and ultrasound can induce cavitation. Laser-induced cavitation is a type of energy deposition-induced cavitation. It uses a laser beam focused on water. Once the laser energy reaches the breakdown threshold, a plasma is generated in the water. The plasma then absorbs the laser energy, generating cavitation bubbles. This method offers advantages such as good spherical symmetry and strong controllability. However, laser-induced cavitation has a limited range, produces a small number of cavitation bubbles, and has a long processing cycle, making it difficult to implement on a large-scale industrial scale. Ultrasonic cavitation is a type of pressure drop-induced cavitation. It utilizes ultrasound waves propagating through a liquid. The liquid oscillates under the influence of ultrasound, forming pressure waves. When the local pressure falls below the saturation gas pressure, a cluster of cavitation bubbles forms within the liquid. The bubbles grow and expand in low-pressure areas, then contract and collapse when they reach high-pressure areas. The collapse of the cavitation bubbles generates shock waves and microjets, which alter the surface properties of the material. However, ultrasonic cavitation suffers from low energy efficiency and random cavitation patterns, making dimensional accuracy difficult to guarantee. Furthermore, single-sided cavitation can produce undesirable deformation due to stress gradients, leading to poor shape control capabilities, especially when applied to thin plates. Summary of the Invention

[0005] In response to the shortcomings of the prior art, the present invention provides a method and processing device for preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic dual cavitation coupling. Ultrasonic cavitation is introduced on the basis of the laser-induced cavitation process. Ultrasonic waves are transmitted into water by directly applying ultrasonic vibrations to the lower surface of the aluminum alloy, so that ultrasonic cavitation occurs near the upper surface of the aluminum alloy, generating a cavitation group to improve the disadvantage of the small number of cavitation bubbles in laser-induced cavitation. More importantly, the thermal effect generated during the collapse of the laser-induced cavitation is utilized to guide the ultrasonic cavitation bubbles to collapse toward the surface of the aluminum alloy, so that the shock waves and microjets generated by the collapse act on the upper surface of the aluminum alloy, forming a micron-level porous structure on the surface of the aluminum alloy and generating an impact pressure that continues to propagate into the interior of the material. The ultrasonic vibration applied at the corresponding position of the lower surface forms a plastic strain of the same magnitude, so that a symmetrical stress distribution is generated in the thickness direction of the specimen, the performance of the aluminum alloy is enhanced and high flatness is maintained, and bending deformation is not easily generated.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] A method for preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic dual cavitation coupling comprises the following steps:

[0008] Install the two ends of the aluminum alloy plate to be processed at the bottom of the cavitation chamber so that the upper surface of the aluminum alloy plate to be processed is immersed in the medium in the cavitation chamber;

[0009] The pulsed laser beam is focused in the medium in the cavitation chamber to generate a laser cavitation zone, and laser-induced cavitation bubbles are generated in the laser cavitation zone; ultrasonic vibration is applied to the lower surface of the aluminum alloy plate to be processed, and an ultrasonic cavitation zone is generated below the laser cavitation zone, and ultrasonic cavitation bubbles are generated in the ultrasonic cavitation zone;

[0010] The fluid dynamics generated by the laser-induced cavitation collapse pushes the ultrasonic cavitation toward the upper surface of the aluminum alloy plate to be processed, and collapses on the upper surface of the aluminum alloy plate to be processed. The shock wave and micro jet generated by the collapse act on the upper surface of the aluminum alloy plate to be processed to form a micron-level porous structure;

[0011] The upper surface of the aluminum alloy plate to be processed after cavitation is chemically modified to reduce the surface energy of the material and form a super-hydrophobic surface.

[0012] Furthermore, the laser-induced cavitation is located 20 to 80 microns above the ultrasonic cavitation zone.

[0013] Furthermore, the pulsed laser beam and the ultrasonic vibration move synchronously along the processing path, so that the entire upper surface of the aluminum alloy plate to be processed forms a micron-level porous structure.

[0014] Furthermore, the pulse energy of the pulse laser beam is 200mJ to 1000mJ, and the defocusing amount is 1mm.

[0015] Furthermore, ultrasonic vibration is generated by an ultrasonic generator, the frequency of the ultrasonic generator is 20kHz to 40kHz, and the amplitude is 30μm to 50μm.

[0016] Furthermore, a circulating heat exchange system is provided outside the cavitation chamber to maintain the temperature of the medium in the cavitation chamber between 30 and 50°C.

[0017] Furthermore, the specific method of reducing the surface energy of the material by chemically modifying the upper surface of the cavitated aluminum alloy plate to be processed is: placing the cavitated aluminum alloy plate to be processed in a 1-3% perfluorooctanoic acid solution for 4 hours, and then drying it in a constant temperature oven at 95°C for 5 minutes.

[0018] A processing device for a method of preparing an aluminum alloy super-hydrophobic surface by laser-ultrasonic dual cavitation coupling comprises a laser, an ultrasonic generator and a cavitation chamber; the laser is used to generate a pulsed laser beam, and the laser is movably mounted above the cavitation chamber. The pulsed laser beam is focused in a liquid medium in the cavitation chamber to generate laser-induced cavitation; an aluminum alloy plate to be processed is mounted at the bottom of the cavitation chamber, and the upper surface of the aluminum alloy plate to be processed is immersed in the medium in the cavitation chamber; the ultrasonic generator is movably mounted below the lower surface of the aluminum alloy plate to be processed, and is used to generate ultrasonic cavitation in the cavitation chamber above the upper surface of the aluminum alloy plate to be processed; the ultrasonic cavitation generated by the ultrasonic generator is located directly below the laser-induced cavitation.

[0019] Furthermore, it also includes a temperature control circulation system, which is located outside the cavitation chamber and is used to regulate the temperature of the liquid medium in the cavitation chamber.

[0020] Furthermore, the temperature control circulation system includes a water tank, a water reservoir, a water pump, a temperature sensor and an industrial computer; the cavitation chamber is located in the water tank, and the water tank forms a closed-loop pipeline with the water pump and the water reservoir; the temperature sensor is used to detect the temperature in the cavitation chamber; the industrial computer controls the operation of the water pump according to the temperature in the cavitation chamber.

[0021] The beneficial effects of the present invention are:

[0022] 1. The method for preparing a super-hydrophobic surface on an aluminum alloy by laser-ultrasonic dual cavitation coupling according to the present invention comprises applying ultrasonic vibrations directly to the lower surface of the aluminum alloy, transmitting ultrasonic waves into water through the aluminum alloy, and forming a group of ultrasonic bubbles near the upper surface. A pulsed laser is focused above the ultrasonic bubble group in water. The fluid flow generated when the generated laser cavitation collapses guides the ultrasonic cavitation to collapse toward the aluminum alloy surface. The shock waves and microjets generated by the collapse act on the upper surface of the aluminum alloy, causing severe plastic deformation on the upper surface and forming impact pits. Under the action of multiple dense cavitations, a micron-sized porous structure is formed on the surface of the aluminum plate. After chemical modification, the prepared micron-sized porous structure and low surface energy work together to achieve a good super-hydrophobic effect on the surface of the aluminum alloy material.

[0023] 2. The method of preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic double cavitation coupling described in the present invention uses laser and ultrasonic double cavitation to generate cavitation bubbles at specific positions and stimulate the collapse of cavitation bubbles. The shock waves and microjets generated by the collapse impact the upper surface of the aluminum alloy multiple times and form an impact pressure that propagates into the interior of the material. At the same time, ultrasonic vibration is applied to the corresponding position of the lower surface, so that both sides are processed simultaneously to produce plastic strains of approximately the same magnitude, so that a symmetrical stress distribution is generated in the thickness direction of the specimen, and the aluminum alloy plate maintains a high degree of flatness.

[0024] 3. The method of preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic double cavitation coupling described in the present invention generates cavitations on the upper surface through laser-ultrasonic double cavitation. When the cavitations collapse, they impact the upper surface of the aluminum alloy. At the same time, ultrasonic vibrations are applied to the corresponding positions on the lower surface. The grain refinement and surface residual compressive stress induced near the surface of the upper and lower surfaces of the workpiece can enhance the fatigue resistance of the matrix, thereby improving the service life of the workpiece under complex working conditions.

[0025] 4. The method of preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic dual cavitation coupling described in the present invention effectively superimposes the two processes, and the process parameters are easy to control. It has the advantages of simple operation and low cost. The prepared micron-level structure has high reliability and stability. It is not only for increasing the number of cavitation bubbles, but more importantly, it couples the two processes, overcomes the disadvantages of a single cavitation process, is better suitable for the complex and harsh environment in the aerospace field, and has a relatively broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. The drawings described below are some embodiments of the present invention. For ordinary technicians in this field, it is obvious that other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 Schematic diagram of the laser-ultrasonic dual cavitation coupling device for preparing super-hydrophobic surface of aluminum alloy described in the present invention.

[0028] Figure 2 This is a morphology diagram of Example 1 of the present invention.

[0029] Figure 3 This is a comparison chart of the droplet contact angles of the super-hydrophobic surfaces prepared in various embodiments of the present invention.

[0030] Figure 4 4 is a comparison diagram of residual stress of various embodiments of the present invention.

[0031] Figure 5 2 is a comparison chart of the microhardness of various embodiments of the present invention.

[0032] Figure 6 This is the residual stress distribution diagram in the thickness direction of Example 2 of the present invention.

[0033] In the picture:

[0034] 1- Pulsed laser beam; 2- Cavitation chamber; 3- Water tank; 4- Temperature sensor; 5- Fixture; 6- Workbench; 8- Aluminum alloy plate to be processed; 9- Ultrasonic vibration device; 10- Water reservoir; 11- Water pump; 12- Industrial computer. DETAILED DESCRIPTION

[0035] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "axial", "radial", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0037] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0038] like Figure 1 As shown, the processing device for preparing super-hydrophobic surfaces of aluminum alloys by laser-ultrasonic dual cavitation coupling described in the present invention includes a laser, an ultrasonic vibration device 9, and a cavitation chamber 2; the laser is used to generate a pulsed laser beam 1, and the laser is movably mounted above the cavitation chamber 2, which contains a liquid medium, generally water. The pulsed laser beam 1 is focused in the liquid medium in the cavitation chamber 2 to generate laser-induced cavitation; a gap is provided in the bottom wall of the cavitation chamber 2, and an aluminum alloy plate 8 to be processed is mounted on the bottom of the cavitation chamber 2 by a fixture 5, and the upper surface of the aluminum alloy plate 8 to be processed is immersed in the medium in the cavitation chamber 2, that is, the upper surface of the aluminum alloy plate 8 to be processed can see the bottom surface of the cavitation chamber 2; the cavitation chamber 2 is mounted on a workbench 6. The ultrasonic vibration device 9 can be movably installed below the lower surface of the aluminum alloy plate to be processed 8, and is used to generate ultrasonic cavitation in the cavitation chamber 2 above the upper surface of the aluminum alloy plate to be processed 8; the ultrasonic generator generates ultrasonic cavitation directly below the laser-induced cavitation, which facilitates the collapse of the laser-induced cavitation and pushes the ultrasonic cavitation to the upper surface of the aluminum alloy plate to be processed 8.

[0039] The system also includes a temperature control circulation system located outside the cavitation chamber 2 and used to regulate the temperature of the liquid medium within the cavitation chamber 2. The system includes a water tank 3, a water reservoir 10, a water pump 11, a temperature sensor 4, and an industrial computer 12. The cavitation chamber 2 is located within the water tank 3, which forms a closed-loop pipeline with the water reservoir 10 via the water pump 11. The temperature sensor 4 is used to detect the temperature within the cavitation chamber 2. The industrial computer 12 controls the water pump 11 based on the temperature within the cavitation chamber 2, directing the liquid within the water reservoir 10 into the water tank 3 to maintain the temperature within the cavitation chamber 2. The medium temperature within the cavitation chamber 2 is generally maintained between 30°C and 50°C.

[0040] The method for preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic dual cavitation coupling of the present invention comprises the following steps:

[0041] Pre-treating the upper and lower surfaces of the aluminum alloy plate 8 to be processed;

[0042] Install both ends of the aluminum alloy plate 8 to be processed at the bottom of the cavitation chamber 2 so that the upper surface of the aluminum alloy plate 8 to be processed is immersed in the medium in the cavitation chamber 2;

[0043] A pulsed laser beam 1 is focused in the medium in the cavitation chamber 2 to generate a laser cavitation zone, and laser-induced cavitation is generated in the laser cavitation zone; ultrasonic vibration is applied to the lower surface of the aluminum alloy plate 8 to be processed, and an ultrasonic cavitation zone is generated below the laser cavitation zone, and ultrasonic cavitation is generated in the ultrasonic cavitation zone; the laser-induced cavitation is 20 to 80 microns directly above the ultrasonic cavitation zone.

[0044] The fluid dynamics generated by the laser-induced cavitation collapse pushes the ultrasonic cavitation toward the upper surface of the aluminum alloy plate 8 to be processed, and collapses on the upper surface of the aluminum alloy plate 8 to be processed. The shock wave and microjet generated by the collapse act on the upper surface of the aluminum alloy plate 8 to be processed. The pulsed laser beam 1 and the ultrasonic vibration move synchronously along the processing path, so that the entire upper surface of the aluminum alloy plate 8 to be processed is formed into a micron-level porous structure;

[0045] The upper surface of the cavitated aluminum alloy plate to be processed 8 is chemically modified to reduce the surface energy of the material and form a super-hydrophobic surface.

[0046] The method for preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic dual cavitation coupling described in the present invention introduces ultrasonic cavitation technology on the basis of laser-induced cavitation. A pulsed laser is continuously focused in water to induce cavitation. At the same time, ultrasonic vibration is directly applied to the lower surface of the substrate to transmit ultrasonic waves into the water and generate a cavitation group below the focused area, thereby improving the disadvantage of a small number of cavitation bubbles in laser-induced cavitation. More importantly, the laser-induced cavitation expands and contracts under the action of ultrasonic vibration and laser energy until it collapses. The fluid flow generated in the liquid guides the ultrasonic cavitation to collapse on the aluminum alloy surface. The shock waves and microjets generated by the collapse repeatedly and densely impact the upper surface of the aluminum alloy, forming a micron-scale porous structure on the upper surface and continuing to propagate the impact pressure into the material. At the same time, ultrasonic vibration is applied to the corresponding position of the lower surface, so that the upper and lower surfaces of the aluminum alloy produce plastic strains of approximately the same size, presenting a symmetrical stress distribution in the thickness direction, which can ensure that the performance of the aluminum alloy is enhanced and maintains good flatness, the overall deformation of the plate is small, and the mechanical stability of the hydrophobic structure is strong.

[0047] Example 1:

[0048] The method for preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic dual cavitation coupling described in Example 1 includes the following specific steps:

[0049] S01: Using sandpaper of different particle sizes, the surface of a 20 mm × 20 mm × 2 mm 2024 aviation aluminum alloy sheet 8 to be processed is polished step by step to a surface roughness of ≤ 50 μm. The surface is ultrasonically cleaned and dried using anhydrous ethanol. The two ends of the aluminum alloy sheet 8 to be processed are mounted at the bottom opening of the cavitation chamber 2.

[0050] S02: Water is injected into the cavitation chamber. The temperature of the water is controlled by the temperature control circulation system. The water inlet and outlet of the water tank are equipped with temperature sensors, and the water in the cavitation chamber is maintained at 30°C through the water circulation system.

[0051] S03: The laser is turned on and focused in water. The pulsed laser beam 1 generates a laser cavitation zone in the medium within the cavitation chamber 2, and laser-induced cavitation bubbles are generated within the laser cavitation zone. The pulse energy of the pulsed laser beam 1 is 200 mJ, and the defocus distance is 1 mm. Simultaneously, the ultrasonic vibration device 9 at the bottom of the cavitation chamber is turned on, with a frequency of 20 kHz and an ultrasonic amplitude of 30 μm. Ultrasonic vibrations are applied to the lower surface of the aluminum alloy sheet 8 to be processed, generating an ultrasonic cavitation zone below the laser cavitation zone and ultrasonic cavitation bubbles within the ultrasonic cavitation zone. The laser-induced cavitation bubbles are located 20 microns directly above the ultrasonic cavitation zone.

[0052] S04: The ultrasonic cavitation is pushed toward the upper surface of the aluminum alloy plate 8 to be processed by the fluid dynamics generated by the laser-induced cavitation collapse, and collapses on the upper surface of the aluminum alloy plate 8 to be processed. The shock wave and microjet generated by the collapse act on the upper surface of the aluminum alloy plate 8 to be processed. The pulsed laser beam 1 and the ultrasonic vibration move synchronously along the processing path, so that the entire upper surface of the aluminum alloy plate 8 to be processed is formed into a micron-level porous structure;

[0053] S05: The cavitated aluminum alloy plate was immersed in a 1% perfluorooctanoic acid solution for 4 hours, and then dried in a constant temperature oven at 95°C for 5 minutes.

[0054] The cavitation surface morphology of the aluminum alloy sample prepared in Example 1 is as follows: Figure 2 As shown in the figure, under the action of "laser-ultrasonic" double cavitation, the generated shock waves and microjets repeatedly and intensively impact the substrate surface, preparing a micron-level porous structure on the surface, achieving surface grain refinement of the substrate and improving the hardness of the material. Figure 3 As shown in the figure, the contact angle of the droplet in the cavitation area was tested by an angular contact meter and was 153°, achieving super-hydrophobicity. The presence of the surface microstructure forms a large number of air pockets on the surface, storing air, effectively reducing the contact area between the droplet and the material surface, thereby reducing the heat transfer between the droplet and the material surface. Figure 4 As shown in FIG1 , the residual stress on the surface of the super-hydrophobic aluminum alloy prepared in Example 1 is -37±3 MPa, achieving the tensile-compressive conversion of the residual stress on the surface of the sample. Figure 5As shown, the microhardness of the aluminum alloy plate prepared in Example 1 is 172 HV.

[0055] Example 2:

[0056] On the basis of Example 1, the pulse energy of the laser beam in Example 2 is 500 mJ, and the ultrasonic vibration device at the bottom of the cavitation chamber is turned on at the same time. The frequency of the ultrasonic generator is 25 kHz, the ultrasonic amplitude is 40 μm, and the temperature in the cavitation chamber is controlled to 40°C. The laser-induced cavitation is 50 microns directly above the ultrasonic cavitation zone.

[0057] The preparation process of the super-hydrophobic surface of the aluminum alloy material in Example 2 is consistent with that in Example 1, but the pulse energy of the laser beam and the ultrasonic vibration parameters are adjusted. The contact angle of the droplet in the cavitation area is tested by an angular contact meter and is 157°, which has good hydrophobicity. The residual stress of the super-hydrophobic aluminum alloy surface prepared in Example 2 is as follows: Figure 4 As shown, the residual compressive stress is -84±4MPa, and the residual stress distribution in the thickness direction of the aluminum alloy plate is measured as follows Figure 6 As shown, the shock waves and microjets generated by the collapse of cavitation impact the upper surface of the aluminum alloy multiple times and densely, while ultrasonic vibrations are applied to the corresponding positions of the lower surface, generating plastic strains of approximately the same magnitude in the thickness direction, which manifests as a symmetrical stress distribution, so that the aluminum alloy plate maintains a high degree of flatness after processing. The microhardness of the aluminum alloy plate prepared in Example 2 is 196HV. On the basis of Example 1, Example 2 uses a larger laser pulse energy and ultrasonic amplitude to increase the cavitation intensity, make the cavitation reaction more intense, and change the contact angle of the material. At the same time, the ultrasonic vibration frequency is increased, the excitation effect on the cavitation bubble is increased, and the cavitation bubble collapse is more intense. Therefore, the sample prepared in Example 2 has better hydrophobic properties and stronger matrix mechanical properties, and the plate has better flatness.

[0058] Example 3:

[0059] On the basis of Example 1, the pulse energy of the laser beam in Example 3 is 800mJ, and the ultrasonic vibration device at the bottom of the cavitation chamber is turned on at the same time. The frequency of the ultrasonic generator is 40kHz, the ultrasonic amplitude is 50μm, and the temperature in the cavitation chamber is controlled to be maintained at 50℃. The laser-induced cavitation is 80 microns above the ultrasonic cavitation zone.

[0060] The preparation process of the super-hydrophobic surface of the aluminum alloy material in Example 3 is consistent with that in Example 1, but the pulse energy of the laser beam and the ultrasonic vibration parameters are further adjusted. The contact angle of the droplet in the cavitation area is tested by an angular contact angle meter and is 162°. The residual compressive stress is -110±4MPa, and the microhardness of the aluminum alloy plate prepared in Example 3 is 211HV.

[0061] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0062] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic dual cavitation coupling, characterized in that: The steps include: Mounting both ends of the aluminum alloy plate (8) to be processed at the bottom of the cavitation chamber (2) so that the upper surface of the aluminum alloy plate (8) to be processed is immersed in the medium in the cavitation chamber (2); A pulsed laser beam (1) is focused in a medium in a cavitation chamber (2) to generate a laser cavitation zone, and laser-induced cavitation bubbles are generated in the laser cavitation zone; ultrasonic vibration is applied to the lower surface of an aluminum alloy plate (8) to be processed, and an ultrasonic cavitation zone is generated below the laser cavitation zone, and ultrasonic cavitation bubbles are generated in the ultrasonic cavitation zone; The fluid dynamics generated by the laser-induced cavitation collapse is used to push the ultrasonic cavitation toward the upper surface of the aluminum alloy plate (8) to be processed, and collapse on the upper surface of the aluminum alloy plate (8) to be processed. The shock wave and micro jet generated by the collapse act on the upper surface of the aluminum alloy plate (8) to form a micron-level porous structure; The upper surface of the aluminum alloy plate (8) to be processed after cavitation is chemically modified to reduce the surface energy of the material and form a super-hydrophobic surface.

2. The method for preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic dual cavitation coupling according to claim 1, characterized in that: The laser-induced cavitation is located 20 to 80 microns above the ultrasonic cavitation zone.

3. The method for preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic double cavitation coupling according to claim 1, characterized in that: The pulsed laser beam (1) and the ultrasonic vibration move synchronously along the processing path, so that the entire upper surface of the aluminum alloy plate (8) to be processed forms a micron-level porous structure.

4. The method for preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic dual cavitation coupling according to claim 1, characterized in that: The pulse energy of the pulse laser beam (1) is 200mJ to 1000mJ, and the defocusing amount is 1mm.

5. The method for preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic dual cavitation coupling according to claim 1, characterized in that: Ultrasonic vibration is generated by an ultrasonic generator with a frequency of 20kHz to 40kHz and an amplitude of 30μm to 50μm.

6. The method for preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic dual cavitation coupling according to claim 1, characterized in that: A circulating heat exchange system is provided outside the cavitation bin (2) to maintain the temperature of the medium in the cavitation bin (2) between 30°C and 50°C.

7. The method for preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic dual cavitation coupling according to claim 1, characterized in that: The specific method for reducing the surface energy of the material by chemically modifying the upper surface of the cavitated aluminum alloy plate (8) to be processed is as follows: the cavitated aluminum alloy plate (8) to be processed is immersed in a 1-3% perfluorooctanoic acid solution for 4 hours, and then dried in a constant temperature oven at 95°C for 5 minutes.

8. A processing device for the method for preparing a super-hydrophobic surface of an aluminum alloy by laser-ultrasonic dual cavitation coupling according to any one of claims 1 to 7, characterized in that: The invention comprises a laser, an ultrasonic generator and a cavitation chamber (2); the laser is used to generate a pulsed laser beam (1), the laser is movably mounted above the cavitation chamber (2), the pulsed laser beam (1) is focused in a liquid medium in the cavitation chamber (2), and is used to generate laser-induced cavitation; an aluminum alloy plate (8) to be processed is mounted at the bottom of the cavitation chamber (2), and the upper surface of the aluminum alloy plate (8) to be processed is immersed in the medium in the cavitation chamber (2); the ultrasonic generator is movably mounted below the lower surface of the aluminum alloy plate (8) to be processed, and is used to generate ultrasonic cavitation in the cavitation chamber (2) above the upper surface of the aluminum alloy plate (8) to be processed; the ultrasonic cavitation generated by the ultrasonic generator is located directly below the laser-induced cavitation.

9. The processing device of the method for preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic dual cavitation coupling according to claim 8, characterized in that: It also includes a temperature control circulation system, which is located outside the cavitation chamber (2) and is used to control the temperature of the liquid medium in the cavitation chamber (2).

10. The processing device of the method for preparing super-hydrophobic surface of aluminum alloy by laser-ultrasonic dual cavitation coupling according to claim 9, characterized in that: The temperature control circulation system comprises a water tank (3), a water reservoir (10), a water pump (11), a temperature sensor (4) and an industrial control computer (12); the cavitation chamber (2) is located in the water tank (3), and the water tank (3) and the water reservoir (10) form a closed-loop pipeline through the water pump (11); the temperature sensor (4) is used to detect the temperature in the cavitation chamber (2); and the industrial control computer (12) controls the operation of the water pump (11) according to the temperature in the cavitation chamber (2).

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