Method for manufacturing arc-shaped water collecting surface by laser peening assisted by pressurized gas environment

Abstract

This invention relates to a method for preparing an arc-shaped water-collecting surface using laser shot peening assisted by a pressurized gas environment. The method includes placing a sealed reaction chamber in a first pressurized gas environment, irradiating the surface of an aluminum plate with a high-energy short-pulse laser under the influence of this environment to prepare a hydrophilic arc-shaped water-collecting region, discharging the gas from the sealed reaction chamber, injecting He gas to maintain this for ten minutes, and then placing the sealed reaction chamber in a second pressurized gas environment. Under the influence of this second pressurized gas environment, irradiating the surface of the aluminum plate with a low-energy short-pulse laser to prepare an arc-shaped superhydrophobic region. This process is repeated alternately. This method facilitates the formation of a denser micro / nano structure on the surface of the aluminum alloy, enabling in-situ generation of carbon / oxygen-based reinforcing phases and further improving the mechanical properties of the aluminum alloy water-collecting surface.

Description

Technical Field

[0001] This invention belongs to the field of laser surface processing technology, specifically a method for preparing an arc-shaped water collection surface by laser shot peening assisted by a pressurized gas environment. Background Technology

[0002] In desert environments, high temperatures, low humidity, and scarce annual precipitation result in chronic water scarcity, severely limiting ecosystem stability and the sustainable development of human activities. Research indicates that, based on biomimetic functional interface design principles, constructing interface structures with synergistic effects of hydrophilic and superhydrophobic regions can effectively induce water vapor condensation, directional transport, and accumulation. Therefore, improving the water-collecting properties of metallic material surfaces has become one of the key issues that need to be addressed in arid and complex environments.

[0003] Currently, various biomimetic techniques are used to construct water-collecting structures, among which laser etching, template replication, and electrospinning are relatively typical. Laser etching utilizes high-energy short-pulse lasers to etch micro- and nano-structures onto material surfaces, controlling regional wettability to achieve hydrophilic / hydrophobic pattern distribution. This method can achieve high-precision pattern control, but the rapid heating and cooling process easily leads to stress concentration, causing a decline in the mechanical properties of the substrate and reducing the service life of the superhydrophobic component. Template replication transfers microstructures to the target material surface using natural or artificial templates, enabling efficient fabrication of simple biomimetic structures. However, it requires high plastic deformation capacity of the target material, has insufficient fabrication capability for nanoscale structures, and has limited ability to control the superhydrophobicity of metal surfaces. Electrospinning can construct large-scale spider silk-like micro / nanofiber networks, relying on capillary attraction and gradient structures on the fiber surface to guide water droplet migration, exhibiting good fog-collecting performance. However, the fiber layer has low mechanical strength, making it difficult to use in complex environments for extended periods.

[0004] Therefore, existing methods for preparing superhydrophobic metal surfaces are limited by their complex manufacturing processes, high costs, damage to the mechanical properties of the substrate material, and lack of durability, making them difficult to apply in arid and complex environments. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment, comprising, Pre-treatment of aluminum alloy fan-shaped plates; Before laser shot peening, the surface area to be treated of the fan-shaped plate is geometrically calibrated. Multiple processing units distributed in an inverted trapezoidal array are calibrated from left to right along the horizontal direction to determine the effective scanning path and range of the laser beam. Each processing unit is divided into energy regions, which are divided into the middle region and the left and right symmetrical regions. The aluminum plate is fixed horizontally inside the sealed reaction chamber; O2 + He are continuously introduced into a sealed reaction chamber to form a first pressurized gas environment, maintaining a high-pressure environment inside the reaction chamber; the first pressurized gas environment is a mixture of inert gas and oxygen-containing active gas; the surface of the aluminum alloy is irradiated by a high-energy short-pulse laser to induce the surface molten material to react with the oxygen-containing active gas to form a hydrophilic structure rich in oxides; Slowly open the pressure relief valve to release the high pressure in the sealed reaction chamber. After the pressure relief is complete, open the active gas outlet and introduce He gas to maintain the pressure for ten minutes. After the first pressurized gas environment is completely emptied, introduce CO to form the second pressurized gas environment. The second pressurized gas environment is a mixture of inert gas and carbon-containing active gas to maintain a high-pressure environment in the sealed reaction chamber. Irradiate the aluminum alloy surface with a low-energy short-pulse laser to induce the surface material to melt and react with the carbon-containing active gas to form a superhydrophobic structure rich in carbides.

[0007] As a preferred technical solution for a method of preparing an arc-shaped water-collecting surface using laser shot peening assisted by a pressurized gas environment, the pretreatment of the aluminum alloy fan-shaped sheet includes, A 1mm thick aluminum plate was produced through multiple cold rolling processes. The aluminum plate was then cut into a fan shape. The surface of the aluminum plate was polished step by step using different numbers of sandpapers to control the surface roughness of the workpiece to 50μm. The aluminum plate was then placed in anhydrous ethanol for ultrasonic cleaning and drying to remove surface impurities.

[0008] In a preferred embodiment of a method for preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment, the oxygen-containing active gas in the first pressurized gas environment is O2 gas, and the volume percentage of the O2 gas in the first pressurized gas environment is 20%~30%; the carbon-containing active gas in the second pressurized gas environment is CO gas, and the volume percentage of the CO gas in the second pressurized gas environment is 10%~20%.

[0009] In a preferred embodiment of a method for preparing an arc-shaped water-collecting surface using laser shot peening assisted by a pressurized gas environment, the pressure of the high-pressure environment generated by the first pressurized gas environment is P1, the pressure of the high-pressure environment generated by the second pressurized gas environment is P2, and P1 < P2.

[0010] In a preferred embodiment of a method for preparing an arc-shaped water-collecting surface by laser shot peening with a pressurized gas environment, the pressure P1 of the high-pressure environment generated by the first pressurized gas environment is 1.0~2.0MPa; and the pressure P2 of the high-pressure environment generated by the second pressurized gas environment is 3.0~5.0MPa.

[0011] As a preferred technical solution for a method of laser shot peening to prepare an arc-shaped water collecting surface in a pressurized gas environment, the flow rate of the mixed gas is 30~50L / min.

[0012] As a preferred technical solution for a method of preparing an arc-shaped water-collecting surface by laser shot peening under pressurized gas environment, the high-energy short-pulse laser parameters for preparing the water-collecting structure are as follows: wavelength 1064nm, pulse energy range 200-300mJ, flat-top distribution, circular spot diameter 500-1000μm, repetition frequency 5-15Hz, and pulse width 10ns-20ns.

[0013] As a preferred technical solution for a method of preparing an arc-shaped water-collecting surface by laser shot peening under pressurized gas environment, the low-energy short-pulse laser parameters for preparing the superhydrophobic structure are as follows: wavelength 1064nm, pulse energy 50-150mJ, flat-top distribution, circular spot diameter 500-1000μm, repetition frequency 5-15Hz, and pulse width 10ns-20ns.

[0014] As a preferred technical solution for a method of preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment, the effective scanning path is specifically as follows: the laser spot scans in a zigzag path in the transverse direction, and the scanning process is carried out layer by layer from the upper layer to the lower layer of the processing unit, with the spot size decreasing layer by layer; During the scanning process, the laser energy parameters are adjusted so that the middle area of ​​the scanning path uses a higher laser energy distribution, while the side areas use a lower laser energy distribution than the middle area.

[0015] As a preferred technical solution for preparing an arc-shaped water-collecting surface by laser shot peening in a pressurized gas environment, the oxygen content in the water-collecting area of ​​the treated aluminum alloy workpiece is 16.56~18.49wt%, and the carbon content in the superhydrophobic area is 26.45~30.58wt%.

[0016] The beneficial effects of this invention are as follows: Under the action of a first pressurized gas environment, a high-energy short-pulse laser irradiates the surface of an aluminum plate. Active oxygen atoms and the surface of the aluminum alloy absorb energy to form a high-temperature and high-pressure plasma. Oxygen atoms further dissociate into oxygen ions. Under the synergistic effect of the high-temperature and high-pressure environment and the plasma expansion shock wave, the molten material on the aluminum alloy surface is fully stirred with oxygen ions, effectively preparing a hydrophilic arc-shaped water-collecting region. Under the action of a second pressurized gas environment, a low-energy short-pulse laser irradiates the surface of an aluminum plate. CO and the surface of the aluminum alloy absorb energy to form a high-temperature and high-pressure plasma, which further decomposes into carbon ions and oxygen ions. Among them, the solubility of active carbon ions in high-temperature liquid metal is significantly higher than that of oxygen atoms. Under the action of the high-temperature and high-pressure environment and the expansion shock wave of the plasma itself, the remelted material generated by the high temperature on the aluminum alloy surface reacts fully with carbon ions to form carbides, increasing the carbon content in the near-surface layer of the aluminum alloy, effectively preparing an arc-shaped superhydrophobic region and improving the hardness and wear resistance of the surface micro-nano structure. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the arc-shaped water-collecting surface prepared by laser shot peening according to the present invention; Figure 2 SEM image of the superhydrophobic porous micro / nano hierarchical structure of the arc-shaped water-collecting surface prepared by laser shot peening as described in Example 1 of this invention; Figure 3 SEM image of the arc-shaped water-collecting surface hydrophilic structure prepared by laser shot peening according to Embodiment 1 of the present invention; Figure 4 A comparison diagram of the contact angles of droplets in the superhydrophobic regions prepared in various embodiments of the present invention; Figure 5 A comparison diagram of near-surface carbon content in the superhydrophobic regions prepared in various embodiments of the present invention; Figure 6 This is a comparison diagram of the contact angles of droplets in the hydrophilic regions prepared in various embodiments of the present invention; Figure 7 A comparison diagram of near-surface oxygen content in the hydrophilic regions prepared in various embodiments of the present invention; Figure 8 The diagram shows the maximum amplitude of near-surface residual compressive stress prepared in various embodiments of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0020] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0021] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth. Example 1

[0022] Reference Figures 1-8 To address the shortcomings of existing technologies, this invention provides a method for preparing arc-shaped water-collecting surfaces using pressurized gas environment-assisted laser peening. The method employs a pressurized gas environment to regulate the expansion of laser-induced plasma, and then performs laser peening on a pre-treated aluminum alloy surface without an absorption layer. During the preparation of the hydrophilic surface, the active gas O2 and the aluminum plate surface absorb laser energy to form a high-temperature, high-pressure plasma, generating a high-pressure shock wave. Under this high-temperature, high-pressure environment, oxygen ions react with the remelted material on the aluminum alloy surface to form a hydrophilic structure with a high oxide content. During the preparation of the superhydrophobic surface, CO in the active gas and the aluminum alloy surface rapidly absorb energy under laser irradiation to form plasma and continuously decompose into active carbon ions. Under this high-temperature, high-pressure environment, carbon ions react with the remelted material on the aluminum alloy surface to form carbides, constructing a superhydrophobic micro / nano hierarchical structure with a high carbon content. Under the action of the shock wave, the aluminum alloy plate undergoes different plastic deformations; the water-collecting area exhibits an inwardly concave arc-shaped deformation, while the superhydrophobic area exhibits an outwardly convex arc-shaped deformation.

[0023] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0024] A method for preparing an arc-shaped water-collecting surface by laser shot peening under pressurized gas environment includes the following steps: Pre-treatment of aluminum alloy fan-shaped plates; The surface area to be treated of the fan-shaped plate is geometrically calibrated, and a set of processing units distributed in an inverted trapezoidal array is calibrated from left to right along the horizontal direction to accurately scan the laser beam and determine the processing range. Next, the energy regions of each processing unit are divided into a central region and left and right symmetrical regions for the purpose of implementing zoned energy control.

[0025] The pretreated aluminum plate workpiece is placed on an impact platform located inside a pressurized gas environment reaction chamber; the aluminum plate is fixed in a horizontal position by a four-corner hydraulic constant force clamping chuck. O2+He is continuously introduced into a sealed reaction chamber to form a first pressurized gas environment, maintaining a high-pressure environment inside the reaction chamber; the first pressurized gas environment is a mixture of inert gas and oxygen-containing active gas; a high-energy short-pulse laser is controlled by a laser driving system to irradiate the surface of the aluminum alloy, inducing the surface molten material to react with the oxygen-containing active gas to form a hydrophilic structure rich in oxides.

[0026] Slowly open the pressure relief valve to release the high pressure in the reaction chamber. After the pressure relief is complete, open the active gas outlet and introduce He gas to maintain it for ten minutes. After the first gas environment is completely emptied, introduce CO to form the second pressurized gas environment. The second pressurized gas environment is a mixture of inert gas and carbon-containing active gas to maintain a high-pressure environment in the reaction chamber. The surface of the aluminum alloy is irradiated by a low-energy short-pulse laser controlled by the laser driving system to induce the surface material to melt and react with the carbon-containing active gas to form a superhydrophobic structure rich in carbides. Furthermore, the aluminum alloy fan-shaped thin plate was pre-treated by grinding with sandpaper of 400#, 800#, 1000#, and 1500# grit, and then polished on a polishing machine to achieve a surface roughness of 50μm. The surface of the workpiece was then ultrasonically cleaned in anhydrous ethanol for 5 minutes and dried for later use. Furthermore, during the forming process, the flow rate of the mixed gas is 30-50 L / min, in order to control the active concentration of the atmosphere in the molten reaction zone within the target range; Furthermore, the oxygen-containing active gas in the first pressurized gas environment is O2 gas, which accounts for 20% to 30% of the total gas volume. The carbon-containing active gas in the second pressurized gas environment is CO gas, which accounts for 10% to 20% of the total gas volume.

[0027] Furthermore, the pressure of the high-pressure environment generated by the first pressurized gas environment is P1, and the pressure of the high-pressure environment generated by the second pressurized gas environment is P2, where P1 < P2.

[0028] Furthermore, the pressure P1 of the high-pressure environment generated by the first pressurized gas environment is 1.0~2.0MPa; the pressure P2 of the high-pressure environment generated by the second pressurized gas environment is 3.0~5.0MPa.

[0029] Furthermore, the laser drive system employs a computer numerical control (CNC) system to control the laser peening process. The scanning path, scanning sequence, and laser process parameters are all automatically invoked by a pre-programmed sequence. The laser spot scans along a zigzag path laterally, with the scanning process proceeding layer by layer from the upper to the lower processing unit, gradually reducing the spot size and adjusting the laser energy parameters layer by layer. Furthermore, the processing sequence is to perform laser processing on the hydrophilic area and the superhydrophobic area sequentially from the left to the right of the plate. That is, after the hydrophilic area is processed, the high-pressure atmosphere environment is changed and the laser processing parameters are adjusted to prepare the superhydrophobic area. The two areas are processed alternately until the process is completed. Furthermore, during the manufacturing process of the hydrophilic structure, the laser energy is pulsed laser. In the first pressurized gas environment, the parameters of the pulsed laser beam are: wavelength 1064nm, pulse energy range 200–300mJ, flat-top distribution, circular spot diameter 500–1000μm, repetition frequency 5–15Hz, and pulse width 10ns–20ns. Specifically, a zoned energy processing method is used for the inverted trapezoidal processing unit: the central area is set with a higher laser energy of approximately 300mJ, while the energy in the left and right side areas is controlled at approximately 200mJ. The high-energy processing in the central area induces surface plastic deformation and remelting of the surface material, while the energy in the side areas is appropriately reduced to avoid excessive deformation of the sheet material and maintain the integrity of the arc-shaped structure.

[0030] Furthermore, during the fabrication of the superhydrophobic structure, the laser energy was pulsed. In the second pressurized gas environment, the parameters of the pulsed laser beam were: wavelength 1064 nm, pulse energy range 50–150 mJ, flat-top distribution, circular spot diameter 500–1000 μm, repetition frequency 5–15 Hz, and pulse width 10–20 ns. The inverted trapezoidal region was also divided into three energy regions, but the overall energy level was significantly reduced. Specifically, the laser energy in the middle region was set to approximately 150 mJ, while the energy in the left and right regions was controlled at approximately 50 mJ. Through hierarchical control at lower energy densities, the arc-shaped, continuously controllable fabrication of aluminum alloy sheets with superhydrophobic micro / nano structures was achieved.

[0031] Furthermore, the oxygen content in the water-collecting area of ​​the treated aluminum alloy workpiece is 16.56-18.49 wt%, and the carbon content in the superhydrophobic area is 26.45-30.58 wt%.

[0032] like Figure 1 As shown, the method for preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment according to the present invention includes the following steps: S01: Grind the aluminum alloy sheet with sandpaper of 400#, 800#, 1000#, and 1500# grit, and polish it on a polishing machine to achieve a surface roughness of 100μm; ultrasonically clean the surface of the workpiece in anhydrous ethanol for 5 minutes and then dry it for later use. S02: Before laser shot peening, the surface area to be treated of the fan-shaped plate is geometrically calibrated, and a set of processing units distributed in an inverted trapezoidal array is calibrated from left to right along the horizontal direction; then, the energy regions of each processing unit are divided into a central region and left and right symmetrical regions for the purpose of implementing zoned energy control.

[0033] S03: Place the processed aluminum plate workpiece on the impact platform, which is located in the pressurized gas environment reaction chamber; fix the aluminum plate with the four-corner hydraulic constant force clamping chuck to make the aluminum plate horizontal. S04: O2 + He are continuously introduced into the sealed reaction chamber to form the first pressurized gas environment, maintaining a high-pressure environment in the reaction chamber; the volume percentage of oxygen is 20% to 30%; the flow rate of all active gases during the LPWC process is maintained at 30 L / min to 50 L / min by gas flow meters at the inlet and outlet; a pressurization pump is used to maintain the high-pressure environment in the reaction chamber, and a pressure gauge is installed in the reaction chamber to ensure that the pressure is in the range of 1.0 to 2.0 MPa; S05: The scribing area (hydrophilic area) on the sample surface is subjected to laser shot peening without absorption layer. The laser shot peening process is controlled by a computer numerical control system (CNC). The scanning path, scanning sequence, and laser process parameters are all automatically called by a pre-programmed program. A circular spot flat-top nanosecond pulse laser is used. The laser spot scans in a zigzag path in the transverse direction. The scanning process is carried out layer by layer from the upper layer to the lower layer of the processing unit, and the spot size is reduced and the laser energy parameters are adjusted layer by layer. The inverted trapezoidal unit adopts a partitioned energy processing method. The laser single pulse energy in the middle area is about 300mJ, and the laser single pulse energy in the left and right side areas is about 200mJ. The processing sequence is to perform laser processing on the hydrophilic area and the superhydrophobic area from the left side of the plate to the right side. That is, after the hydrophilic area is processed, the high-pressure atmosphere environment is changed and the laser processing parameters are adjusted to prepare the superhydrophobic area. The two areas are processed alternately until the process is completed. S06: Slowly open the pressure relief valve to release the high pressure in the reaction chamber. After the pressure is released, open the active gas outlet and introduce He gas to maintain it for ten minutes. After the first gas environment is completely emptied, introduce CO to form the second pressurized gas environment. The volume percentage of CO gas is 10% to 20%. Use a pressurization pump to maintain the high pressure environment in the reaction chamber. Install a pressure gauge in the reaction chamber to detect and ensure that the pressure is in the range of 3.0 to 5.0 MPa. S07: The additional scribing area (superhydrophobic area) on the sample surface is subjected to laser peening without absorption layer. The laser peening process is controlled by a computer numerical control system (CNC). The scanning path, scanning sequence and laser process parameters are automatically called by a pre-programmed program. A circular spot flat-top nanosecond pulse laser is used. The laser spot scans in a zigzag path in the transverse direction. The scanning process is carried out layer by layer from the upper layer to the lower layer of the processing unit, and the spot size and laser energy parameters are adjusted layer by layer. The inverted trapezoidal unit adopts a partitioned energy processing method, and the overall energy level is relatively reduced. The laser single pulse energy in the middle area is about 150mJ, and the laser single pulse energy in the left and right side areas is about 100mJ.

[0034] S08: After laser shot peening, ultrasonic cleaning is used to remove residual deposits on the surface of the micro-nano structure, thereby achieving the preparation of an arc-shaped water collection surface.

[0035] The present invention discloses a method for preparing an arc-shaped water-collecting surface by pressurized gas environment-assisted laser shot peening. A flat-top nanosecond pulsed laser is used to continuously inject carbon- and oxygen-containing active gases into a reaction chamber while maintaining a high-pressure environment. A high-energy short-pulse laser is used as the irradiation heat source to perform laser shot peening on an aluminum alloy sheet without an absorption layer. During the shot peening process, the molten material on the aluminum alloy surface reacts fully with the carbon- and oxygen-containing active ions to form a functionally reinforced phase. The prepared arc-shaped superhydrophobic region exhibits high hardness and high wear resistance, while the arc-shaped water-collecting region exhibits excellent hydrophilicity and water-collecting capacity. When the laser energy is 200-300 mJ, the peak pressure of the laser-induced shock wave is significantly increased. Under the constraint of the pressurized gas environment, a GPa-level impact load is formed and propagates from the surface to the depth of the material. At this point, the shock wave depth significantly increases and penetrates the material, causing the material to undergo overall plastic flow under ultra-high strain rate conditions. The impact area gains inward inertial displacement, resulting in an inward concave deformation of the processed area. When the laser energy is 50-150 mJ, the impact pressure and depth are relatively low, and the shock wave attenuates rapidly in the thickness direction. Plastic deformation is mainly limited to the surface area of ​​the material. At this time, the surface material undergoes significant plastic flow under impact, while the internal material deforms weakly, forming an uneven residual stress distribution along the thickness direction. That is, the surface is dominated by compressive stress, while the internal stress is relatively small, with a significant stress gradient. During the stress release process, a negative bending moment is formed, causing the processed area to exhibit convex deformation. At the same time, the near-surface structure grains are refined, surface dislocations multiply, and high-amplitude residual stress is generated inside the material, thereby improving the mechanical properties of the aluminum alloy matrix material. Using oxygen-containing active gas as the atmosphere dopant in the preparation process of the arc-shaped water collection structure, it dissociates under laser irradiation. The release of active oxygen atoms and their full reaction with the molten material on the surface enhances the performance of the water collection area. Using a carbon-containing active gas as the process atmosphere doping agent for the arc-shaped superhydrophobic structure allows for the dissociation of active carbon atoms under laser irradiation, forming plasma. Under high temperature, high pressure, and the expansion impact of the plasma, the carbon atoms react with the molten material on the workpiece surface, significantly increasing the carbon content of the aluminum alloy surface layer and further enhancing the hardness and wear resistance of the arc-shaped superhydrophobic micro / nano structure. High-pressure laser peening without an absorption layer further increases the reaction concentration of the molten metal with carbon and oxygen elements on the workpiece surface, promoting the formation of carbides and oxides on the aluminum alloy surface. This improves the material forming quality while also further enhancing the mechanical properties of the matrix material.

[0036] The beneficial effects of this invention are as follows: The present invention relates to a method for preparing an arc-shaped water-collecting surface by pressurized gas environment-assisted laser shot peening. Under the action of a first pressurized gas environment, a high-energy short-pulse laser irradiates the surface of an aluminum plate. Active oxygen atoms and the surface of the aluminum alloy plate absorb energy to form a high-temperature and high-pressure plasma. The oxygen atoms further dissociate into oxygen ions. Under the synergistic effect of the high-temperature and high-pressure environment and the plasma expansion shock wave, the molten material on the aluminum alloy surface is fully stirred with oxygen ions, effectively preparing a hydrophilic arc-shaped water-collecting region.

[0037] The present invention discloses a method for preparing an arc-shaped water-collecting surface by laser shot peening under a pressurized gas environment. Under the action of a second pressurized gas environment, a low-energy short-pulse laser irradiates the surface of an aluminum plate. CO and the surface of the aluminum alloy plate absorb energy to form a high-temperature and high-pressure plasma, which further decomposes into carbon ions and oxygen ions. Among them, the solubility of active carbon ions in high-temperature liquid metal is significantly higher than that of oxygen atoms. Under the action of high-temperature and high-pressure environment and the expansion shock wave of the plasma itself, the remelted material generated by the high temperature on the aluminum alloy surface reacts fully with the carbon ions to form carbides, thereby increasing the carbon content of the near-surface layer of the aluminum alloy. This effectively prepares an arc-shaped superhydrophobic region and improves the hardness and wear resistance of the surface micro-nano structure.

[0038] The method for preparing an arc-shaped water collection surface by pressurized gas environment-assisted laser peening of the present invention adopts a zoned energy-controlled laser peening scanning method, applying different energies to different regions within the processing unit to form a stable energy gradient distribution, so that the arc-shaped water collection surface has curvature continuity, thereby realizing zoned energy control.

[0039] The present invention discloses a method for preparing an arc-shaped water-collecting surface using pressurized gas environment-assisted laser peening. High-energy short-pulse lasers directly irradiate the aluminum alloy surface. The active gas and the aluminum alloy surface continuously absorb laser energy to generate plasma. Under the confinement of the high-pressure atmosphere, a shock wave of GPa magnitude propagates into the matrix material, causing the plate to exhibit ultra-high strain rate plastic deformation. When using 50–150 mJ laser peening, the plate exhibits an outwardly convex arc shape; while when using 200–300 mJ laser peening, the plate deforms into an inwardly concave arc shape. Using two different laser energies refines the near-surface grain structure of the material, increases surface dislocations, and generates high-amplitude residual stress within the material, thereby improving the mechanical properties of the aluminum alloy matrix material.

[0040] The method for preparing arc-shaped water collection surfaces by laser shot peening under pressurized gas environment of the present invention significantly improves the nucleation rate of the sample surface under high pressure, prompting more atomic groups to participate in crystal nucleation, making the grains more refined and the microstructure more uniform; at the same time, the high pressure constraint significantly improves the density of active atoms, realizing the in-situ formation of carbon-based / oxygen-based strengthening phases, and further improving the mechanical properties of aluminum alloy water collection surfaces.

[0041] The method for preparing arc-shaped water-collecting surfaces using pressurized gas environment-assisted laser peening of the present invention employs a four-corner hydraulic constant-force clamping chuck to simultaneously apply constant and equal-pressure clamping force at four positions on the workpiece, preventing displacement, warping, and clamping deformation of the fan-shaped plate under laser peening. The hydraulic constant-force mechanism of this chuck can compensate in real time for clamping force attenuation caused by impact loads, maintaining continuous stability of the clamping state.

[0042] The method for preparing arc-shaped water-collecting surfaces by pressurized gas environment-assisted laser shot peening of the present invention includes a method where all process parameters, including pulse parameters, laser parameters, high pressure, and atmosphere parameters, can be controlled by algorithms. It has the advantages of simple operation, low cost, and high efficiency. Since the present invention can continuously construct functional regions with convex superhydrophobic structures and concave water-collecting structures on the same aluminum alloy thin plate, it is suitable for desert water intake device applications and has significant engineering application value and industrial promotion prospects.

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, aluminum alloy is selected as the research object below, and the invention will be described in detail with reference to specific embodiments.

[0044] Example 1: The method for preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment in Example 1 includes the following steps: The aluminum alloy sheet was sanded with sandpaper of 400#, 800#, 1000# and 1500# grit, and then polished on a polishing machine to achieve a surface roughness of 50μm. The surface of the workpiece was then ultrasonically cleaned in anhydrous ethanol for 5 minutes and dried for later use. Before laser shot peening, the surface area to be treated of the fan-shaped plate is geometrically calibrated, and a set of processing units distributed in an inverted trapezoidal array is calibrated from left to right along the horizontal direction. Then, the energy regions of each processing unit are divided into a central region and left and right symmetrical regions for the purpose of implementing zoned energy control.

[0045] Before laser shot peening, the reaction chamber is cleaned, and the treated aluminum plate workpiece is placed on the impact platform, which is located in the pressurized gas environment reaction chamber. The aluminum plate is fixed by the four-corner hydraulic constant force clamping chuck to keep the aluminum plate in a horizontal position. O2 + He are continuously introduced into a closed reaction chamber to form a first pressurized gas environment, maintaining a high-pressure environment in the reaction chamber; the volume ratio of oxygen is 20%; the flow rate of all active gases is maintained at 50 L / min during the LPWC process by gas flow meters at the inlet and outlet; a pressurized pump is used to maintain the high-pressure environment in the reaction chamber, and a pressure gauge is installed in the reaction chamber to ensure that the pressure is 2.0 MPa; The scribing area (hydrophilic area) on the sample surface was subjected to laser peening without absorption layer. The laser peening process was controlled by a computer numerical control system (CNC). The scanning path, scanning sequence, and laser process parameters were all automatically called by a pre-programmed program. A circular spot flat-top nanosecond pulse laser was used. The laser spot scanned in a zigzag path in the transverse direction. The scanning process was carried out layer by layer from the upper layer to the lower layer of the processing unit, and the spot size and laser energy parameters were adjusted layer by layer. A high-frequency Nd:YAG nanosecond laser was selected, and a circular spot flat-top pulse nanosecond laser was used. The specific parameters of the laser peening were: wavelength 1064nm, flat-top distribution, circular spot diameter gradually decreasing from 1000μm to 500μm, repetition frequency 5Hz, pulse width 10ns, and a multi-point overlapping large-area impact method with a row and column spot overlap rate of 60%. The laser energy in the middle area was set to about 300mJ, and the energy in the left and right side areas was controlled to about 200mJ. Slowly open the pressure relief valve to release the high pressure in the reaction chamber. After the pressure is released, open the active gas outlet and introduce He gas for 15 minutes. After the first gas environment is completely emptied, introduce CO to form the second pressurized gas environment. The volume percentage of CO gas is 10%. The flow rate of all active gases is maintained at 50 L / min during the LPWC process, as detected by the gas flow meters at the inlet and outlet. A pressurization pump is used to maintain the high pressure environment in the reaction chamber. A pressure gauge is installed in the reaction chamber to detect and ensure that the pressure is within the range of 3.0 MPa. The superhydrophobic region (an additional scribing area) on the sample surface was subjected to laser peening without an absorption layer. The laser peening process was also controlled by a computer numerical control system (CNC). The scanning path and scanning sequence were controlled by a circular spot flat-top nanosecond pulse laser. The laser spot scanned in a zigzag path in the transverse direction. The scanning process was carried out layer by layer from the upper layer to the lower layer of the processing unit, and the spot size and laser energy parameters were adjusted layer by layer. The specific parameters of the laser peening were: wavelength 1064nm, flat-top distribution, circular spot diameter gradually decreasing from 1000μm to 500μm, repetition frequency 5Hz, pulse width 10ns, and a multi-point overlapping large-area impact method with a 60% overlap rate between row and column spots. The laser energy in the middle area was set to about 150mJ, and the laser energy in the left and right side areas was controlled to about 100mJ. After laser peening, ultrasonic cleaning is used to remove residual deposits on the surface of the micro-nano structure, thus achieving the preparation of an arc-shaped water collection surface.

[0046] The arc-shaped water-accumulating surface prepared in Example 1 is as follows: Figure 2 As shown, the superhydrophobic region exhibits a high-density micro-nano porous structure with a high carbon content. Upon contact with droplets, it can trap a large amount of air, forming an air cushion that significantly reduces the contact area between the droplet and the aluminum alloy surface, thus giving the aluminum alloy workpiece processing unit superhydrophobic properties. Figure 3As shown, the hydrophilic region has a low micro-nano pore density, allowing for sufficient wetting of the liquid upon contact with the droplet. The liquid easily spreads on the surface, forming a stable solid-liquid interface, significantly increasing the actual contact area between the droplet and the aluminum alloy surface. This results in the aluminum alloy fan-shaped sheet processing unit exhibiting excellent hydrophilic properties. Figure 4 As shown, the water contact angle, measured by an angular contact meter, is 158°; Figure 5 As shown, the carbon content of the micro-nano structure on the surface of the superhydrophobic region of the aluminum alloy is 16.56 wt%, which significantly increases the carbon content on the material surface, greatly improving the wear resistance and hardness of the aluminum alloy sheet; for example... Figure 6 As shown, the water contact angle, measured by an angular contact meter, is 9°; Figure 7 As shown, the oxygen content of the micro-nano structure on the surface of the water collection area of ​​the aluminum alloy is 26.45 wt%, which significantly increases the oxygen content on the material surface and greatly improves the water collection performance of the aluminum alloy sheet; Figure 8 As shown, the maximum amplitude of residual compressive stress near the surface reaches 156.4 MPa.

[0047] Example 2 Based on Example 1, in Example 2, the flow rate of all active gases was maintained at 40 L / min, the first gas environment was He + 25% O2, and the pressure was maintained at 1.5 MPa; the second mixed active gas was He + 15% CO, and the pressure was maintained at 4.0 MPa. Compared to the material prepared in Example 1, the sample material obtained in Example 2 has a finer overall microstructure, such as... Figure 4 As shown, the water contact angle, measured by an angular contact meter, is 162°; Figure 5 As shown, the carbon content of the micro-nano structure on the surface of the superhydrophobic region of the aluminum alloy is 17.63 wt%; Figure 6 As shown, the water contact angle, measured by an angular contact meter, is 7°; Figure 7 As shown, the oxygen content of the micro-nano structure on the surface of the aluminum alloy water collection area is 28.93 wt%; Figure 8 As shown, the maximum amplitude of residual compressive stress near the surface reaches 170.1 MPa.

[0048] Example 3 Based on Example 1, in Example 2, the flow rate of all active gases is maintained at 30 L / min, the first mixed active gas is He + 30% O2, and the pressure is maintained at 1.0 MPa; the second mixed active gas is He + 20% CO, and the pressure is maintained at 5.0 MPa. Compared to the material prepared in Example 1, such as Figure 4 As shown, in Example 3, the water contact angle of the sample surface, measured by an angular contact measuring instrument, was 164°; Figure 5 As shown, the carbon content of the micro-nano structure on the surface of the superhydrophobic region of the aluminum alloy is 18.49 wt%; Figure 6 As shown, the water contact angle, measured by an angular contact meter, is 5°; Figure 7 As shown, the oxygen content of the micro-nano structure on the surface of the aluminum alloy water collection area is 30.58 wt%; Figure 8 As shown, the maximum amplitude of residual compressive stress near the surface reaches 190.4 MPa.

[0049] It should be noted that surface wettability is usually characterized by the droplet contact angle: θ < 10° is superhydrophilic, 10° ≤ θ < 90° is hydrophilic, 90° ≤ θ < 150° is hydrophobic, and θ ≥ 150° is superhydrophobic. This theory is well known to those skilled in the art, so the effects corresponding to the data shown in the examples will not be elaborated further.

[0050] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those of ordinary skill in the art who benefit from this disclosure, the development effort will be a routine task in design, manufacturing, and production without requiring extensive experimentation.

[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing an arc-shaped water-collecting surface using laser shot peening assisted by a pressurized gas environment, characterized in that: include, Pre-treatment of aluminum alloy fan-shaped plates; Before laser shot peening, the surface area to be treated of the fan-shaped plate is geometrically calibrated. Multiple processing units distributed in an inverted trapezoidal array are calibrated from left to right along the horizontal direction to determine the effective scanning path and range of the laser beam. Each processing unit is divided into energy regions, which are divided into the middle region and the left and right symmetrical regions. The aluminum plate is fixed horizontally inside the sealed reaction chamber; O2 + He are continuously introduced into a sealed reaction chamber to form a first pressurized gas environment, maintaining a high-pressure environment inside the reaction chamber; the first pressurized gas environment is a mixture of inert gas and oxygen-containing active gas; the surface of the aluminum alloy is irradiated by a high-energy short-pulse laser to induce the surface molten material to react with the oxygen-containing active gas to form a hydrophilic structure rich in oxides; Release the high pressure in the sealed reaction chamber, and after the pressure is released, open the active gas outlet and introduce He gas to completely vent the first pressurized gas environment. Then introduce CO to form the second pressurized gas environment. The second pressurized gas environment is a mixture of inert gas and carbon-containing active gas to maintain a high-pressure environment in the sealed reaction chamber. Irradiate the aluminum alloy surface with a low-energy short-pulse laser to induce the surface material to melt and react with the carbon-containing active gas to form a superhydrophobic structure rich in carbides.

2. The method for preparing an arc-shaped water-collecting surface using laser shot peening assisted by a pressurized gas environment according to claim 1, characterized in that: The pretreatment of the aluminum alloy fan-shaped sheet includes... Cut the aluminum plate into a fan shape; use different numbers of sandpaper to polish the surface of the aluminum plate step by step to control the surface roughness of the workpiece to 50μm; The aluminum plate was ultrasonically cleaned in anhydrous ethanol and then dried to remove surface impurities.

3. The method for preparing an arc-shaped water-collecting surface using laser shot peening assisted by a pressurized gas environment according to claim 1, characterized in that: The oxygen-containing active gas in the first pressurized gas environment is O2 gas, and the volume percentage of O2 gas in the first pressurized gas environment is 20%~30%; the carbon-containing active gas in the second pressurized gas environment is CO gas, and the volume percentage of CO gas in the second pressurized gas environment is 10%~20%.

4. The method for preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment according to claim 1, characterized in that: The pressure of the high-pressure environment generated by the first pressurized gas environment is P1, and the pressure of the high-pressure environment generated by the second pressurized gas environment is P2, and P1 < P2.

5. The method for preparing an arc-shaped water-collecting surface using laser shot peening assisted by a pressurized gas environment according to claim 4, characterized in that: The pressure P1 of the high-pressure environment generated by the first pressurized gas environment is 1.0~2.0MPa; the pressure P2 of the high-pressure environment generated by the second pressurized gas environment is 3.0~5.0MPa.

6. The method for preparing an arc-shaped water-collecting surface using laser shot peening assisted by a pressurized gas environment according to claim 1, characterized in that: The flow rate of the mixed gas is 30~50L / min.

7. The method for preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment according to claim 1, characterized in that: The specific parameters of the high-energy short-pulse laser used to prepare the water collection structure are as follows: wavelength 1064nm, pulse energy range 200-300mJ, flat-top distribution, circular spot diameter 500-1000μm, repetition frequency 5-15Hz, and pulse width 10ns-20ns.

8. The method for preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment according to claim 7, characterized in that: The specific parameters of the low-energy short-pulse laser used to prepare the superhydrophobic structure are as follows: wavelength 1064 nm, pulse energy 50-150 mJ, flat-top distribution, circular spot diameter 500-1000 μm, repetition frequency 5-15 Hz, and pulse width 10 ns-20 ns.

9. The method for preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment according to claim 1, characterized in that: The effective scanning path is as follows: the laser spot scans in a zigzag pattern along the horizontal direction. The scanning process is carried out layer by layer from the upper layer to the lower layer of the processing unit, and the spot size is reduced layer by layer. During the scanning process, the laser energy parameters are adjusted so that the middle area of ​​the scanning path uses a higher laser energy distribution, while the side areas use a lower laser energy distribution than the middle area.

10. The method for preparing an arc-shaped water-collecting surface by laser shot peening assisted by a pressurized gas environment according to claim 1, characterized in that: After treatment, the oxygen content in the water-collecting area of ​​the aluminum alloy workpiece surface is 16.56–18.49 wt%, and the carbon content in the superhydrophobic area is 26.45–30.58 wt%.

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