An apparatus and method for preparing an aluminum alloy corrosion-resistant layer based on laser shock peening

Abstract

This invention discloses an apparatus and method for preparing a corrosion-resistant layer on aluminum alloy based on laser shock peening, relating to the field of aluminum alloy anti-corrosion treatment technology. The invention includes: a traveling mechanism that can travel along the length of the aluminum alloy to be strengthened on its surface; a laser strengthening mechanism comprising a first laser strengthening component and a second laser strengthening component; the emitting end of the first laser strengthening component corresponds to the front end of the traveling mechanism along its traveling direction, and the emitting end of the second laser strengthening component corresponds to the rear end of the traveling mechanism along its traveling direction; a coating mechanism rotatably mounted at the rear end of the traveling mechanism, and its conveying surface rolls on the surface of the aluminum alloy to be strengthened below the emitting end of the second laser strengthening component; and an absorption layer roll-up. This invention can sequentially complete laser shock peening with and without an absorption layer through the forward movement of the traveling mechanism, resulting in high production efficiency.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy corrosion protection technology, specifically to an apparatus and method for preparing an aluminum alloy corrosion-resistant layer based on laser shock peening. Background Technology

[0002] Aluminum alloys are widely used in shipbuilding, aerospace, and rail transportation due to their excellent specific strength and good fatigue properties. In recent years, through the control of alloying elements and optimization of production processes, the strength of aluminum alloys has been continuously improved. However, as the strength of aluminum alloys increases, their corrosion resistance decreases, and they become more susceptible to stress corrosion cracking. This is mainly because the strength of aluminum alloys is significantly improved through precipitation strengthening and solid solution strengthening. The precipitates produced by heat treatment usually have a large difference in corrosion potential with the aluminum matrix, forming local galvanic cells; and the elements in solid solution-strengthened aluminum alloys are prone to segregation, resulting in localized preferential selective corrosion. For example, in 2xxx series Al-Cu aluminum alloys, copper-rich precipitates (Al2Cu) ranging from hundreds of micrometers to nanometers are distributed in the matrix. Cu increases the corrosion potential of these precipitates, leading to severe galvanic corrosion as galvanic cells form between the precipitates and the aluminum matrix in humid environments, resulting in corrosion pits and damaging the surface integrity of the aluminum alloy components. In 5xxx series Al-Mg aluminum alloys, strength is primarily enhanced by solid solution strengthening from magnesium (Mg). However, during casting, Mg tends to segregate at grain boundaries. Increased Mg content at grain boundaries lowers their corrosion potential, causing preferential corrosion at these boundaries in corrosive environments. Furthermore, these grain boundaries provide diffusion channels for Cl- and H+ ions, allowing corrosion to propagate from the surface grain boundaries into the material's interior, resulting in severe intergranular corrosion. Therefore, with the development of new high-strength aluminum alloys, corrosion resistance is a key factor determining the application range, service life, and reliability of aluminum alloys.

[0003] For aluminum alloys, reducing grain size and increasing surface dislocation density can increase the stored energy of the exposed surface, allowing the aluminum alloy matrix to form an oxide film more quickly in corrosive environments to protect the matrix. The residual compressive stress field can also reduce grain boundary oxidation and stress corrosion sensitivity. Laser shock peening (LSP), as an advanced laser surface strengthening technology, has attracted widespread attention in recent years. This technology uses a high-energy-density short-pulse laser to induce a plasma explosion on an absorption layer arranged on the material surface. The shock wave generated by the explosion is constrained by the confinement layer and propagates further into the material, resulting in intense plastic deformation at ultra-high strain rates on the material surface. It offers advantages such as non-contact operation, environmental friendliness, high accessibility, and precise controllability. Numerous studies have shown that compared to traditional shot peening and ultrasonic strengthening, LSP can produce more significant strengthening effects, including deeper strengthening regions and higher residual compressive stress amplitudes. Currently, conventional LSP methods have been proven to refine grains and introduce high-density dislocations and residual compressive stress on aluminum alloy surfaces, thus improving corrosion resistance to some extent. Furthermore, a dense Al2O3 oxide film can instantly form on the surface of aluminum alloys in an atmospheric environment, providing a certain degree of protection to the aluminum alloy substrate. However, the thickness of this oxide film is typically only tens of nanometers, making it highly susceptible to cracking under corrosive environments and external forces. Laser shock peening with an absorption layer is merely a purely mechanical process and cannot directly affect the thickness of the Al2O3 oxide film, nor can it improve the uneven surface corrosion potential caused by alloying elements and precipitated phases on the aluminum alloy surface.

[0004] When using laser shock peening without an absorption layer, the laser energy acts directly on the aluminum alloy surface, causing ablation. The aluminum alloy surface oxidizes in a flowing water layer (constraint layer), producing an Al2O3 oxide film several micrometers thick. This oxide film is a highly promising and easily obtainable corrosion-resistant layer. However, due to the lack of an absorption layer, the laser exerts a thermal effect on the aluminum alloy surface. The ablation process promotes the remelting of surface alloying elements and precipitated phases into the aluminum matrix, but the residual compressive stress amplitude decreases significantly, and the Al2O3 oxide film has low density. Therefore, laser shock peening without an absorption layer can be used to directly prepare an Al2O3 oxide film on the aluminum alloy surface. Further, a laser shock peening process with an absorption layer can be used to generate pure mechanical force to increase the residual compressive stress amplitude and compact the Al2O3 oxide film, thereby significantly improving its density and enhancing the corrosion resistance of the aluminum alloy. However, existing technologies lack devices and methods that organically combine laser shock peening methods with and without absorption layers to prepare high-quality corrosion-resistant layers. Summary of the Invention

[0005] In view of this, the present invention aims to provide an apparatus and method for preparing a corrosion-resistant layer of aluminum alloy based on laser shock stabilization, so as to organically combine laser shock stabilization methods with and without absorption layers.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening includes:

[0008] A walking mechanism that can travel along the length of the aluminum alloy to be strengthened on its surface;

[0009] A laser strengthening mechanism, comprising a first laser strengthening component and a second laser strengthening component; the emitting end of the first laser strengthening component corresponds to the front end of the walking mechanism along its traveling direction, and the emitting end of the second laser strengthening component corresponds to the rear end of the walking mechanism along its traveling direction.

[0010] A coating mechanism is rotatably mounted at the rear end of the walking mechanism, and its conveying surface rolls on the aluminum alloy surface to be strengthened below the emitting end of the second laser strengthening component.

[0011] An absorbent layer roll film, one end of which is mounted on the coating mechanism and the other end is conveyed along the conveying surface of the coating mechanism;

[0012] The first focused pulsed laser beam emitted from the emitting end of the first laser strengthening component can irradiate the aluminum alloy surface to be strengthened to perform laser shock strengthening without absorption layer. As the walking mechanism moves forward, the second focused pulsed laser beam emitted from the emitting end of the second laser strengthening component passes through the absorption layer film and irradiates the aluminum alloy surface that has been strengthened by laser shock without absorption layer to perform laser shock strengthening with absorption layer, so as to form a corrosion-resistant layer of aluminum alloy.

[0013] The beneficial effects of the present invention are as follows: The first focused pulsed laser beam emitted by the first laser strengthening component can irradiate the surface of the aluminum alloy to be strengthened to perform laser shock irradiation without absorption layer. As the walking mechanism moves forward, the coating mechanism simultaneously coats the surface, so that the absorbent layer film is tightly attached to the aluminum alloy surface that has undergone laser shock irradiation without absorption layer. At the same time, the second focused pulsed laser beam emitted by the second laser strengthening component can penetrate the absorbent layer film and irradiate the aluminum alloy surface that has undergone laser shock irradiation without absorption layer to perform laser shock irradiation with absorption layer again. That is, one laser shock irradiation without absorption layer and one laser shock irradiation with absorption layer are completed on the aluminum alloy surface in sequence to form an aluminum alloy corrosion-resistant layer with excellent corrosion resistance.

[0014] Preferably, the walking mechanism includes a top plate, a support member, a connecting back plate, and walking wheels. The top end of the support member is fixed to the bottom of the top plate, the top end of the connecting back plate is fixed to the bottom of the support member, and the walking wheels are rotatably mounted on the bottom of the connecting back plate, with their rolling surfaces able to roll on the aluminum alloy surface to be strengthened.

[0015] Preferably, the first laser strengthening component includes a first pulsed laser, a first reflector, and a first galvanometer laser head. The first reflector is fixed to the front end of the support member, and its incident end corresponds to the emitting end of the first pulsed laser. The first galvanometer laser head is fixed to the connecting back plate below the first reflector, and its receiving end corresponds to the reflecting end of the first reflector. The first focused pulsed laser beam emitted by the first galvanometer laser head can reciprocate along the length direction of the aluminum alloy to be strengthened on its surface.

[0016] Preferably, the second laser strengthening component includes a second pulsed laser, a second reflector, and a second galvanometer laser head. The second pulsed laser is positioned below the first pulsed laser. The second reflector is fixed to the rear end of the support member, and its incident end corresponds to the emitting end of the second pulsed laser. The second galvanometer laser head is fixed to the connecting back plate below the second reflector, and its receiving end corresponds to the reflecting end of the second reflector. The second focused pulsed laser beam emitted by the second galvanometer laser head can pass through the absorption layer film at the corresponding conveying surface and reciprocate along the length direction of the aluminum alloy to be strengthened on its surface.

[0017] Preferably, the energy of the first pulsed laser beam emitted by the first pulsed laser is higher than the energy of the second pulsed laser beam emitted by the second pulsed laser.

[0018] Preferably, the coating mechanism includes an output wheel, a conveying assembly, and a recovery wheel. The output wheel is rotatably mounted on the rear end of the connecting back plate. The conveying assembly is rotatably mounted on the bottom of the connecting back plate corresponding to the second galvanometer laser head. The recovery wheel is rotatably mounted on the connecting back plate above the conveying assembly. One end of the absorbent layer film is wound onto the output wheel, and the other end can extend along the conveying surface of the conveying assembly and be wound onto the recovery wheel.

[0019] The conveying assembly includes a plurality of pressure rollers arranged at intervals along the length of the aluminum alloy to be strengthened and rotatably connected to the bottom rear end of the connecting back plate, with the lower end of each pressure roller being the conveying surface.

[0020] Preferably, a water spraying mechanism is also provided, which includes a water storage tank, a water supply pipe, a first nozzle, and a second nozzle. The water storage tank has a water outlet, and the water inlet end of the water supply pipe is connected to the water outlet. The first nozzle is fixed to the connecting back plate below the first galvanometer laser head, and its water inlet end is connected to the water supply pipe. Its water outlet end corresponds to the aluminum alloy surface below the first galvanometer laser head, so as to form a first constraint layer on the aluminum alloy surface to be strengthened below the first galvanometer laser head. The second nozzle is fixed to the connecting back plate below the second galvanometer laser head, and its water inlet end is connected to the water supply pipe. Its water outlet end corresponds to the upper surface of the absorption layer film below the second galvanometer laser head, so as to form a second constraint layer on the upper surface of the absorption layer film below the second galvanometer laser head.

[0021] Preferably, a plurality of wiper blades are also provided, which are arranged at intervals along the length direction of the aluminum alloy to be strengthened and fixed at the bottom of the connecting back plate between the first galvanometer laser head and the second galvanometer laser head. The scraping end of each wiper blade can abut against the surface of the aluminum alloy to be strengthened.

[0022] A method for preparing a corrosion-resistant layer of aluminum alloy based on laser shock peening, using the laser shock peening strengthening aluminum alloy corrosion-resistant layer preparation apparatus as described above, includes the following steps:

[0023] S1, clean oil stains on the surface of the aluminum alloy to be strengthened;

[0024] S2, Assemble the absorbent layer roll film onto the coating mechanism;

[0025] S3, place the adjusted walking mechanism on the aluminum alloy to be strengthened to ensure that the absorbent layer roll film can be tightly adhered to the aluminum alloy surface along with the conveying surface of the coating mechanism.

[0026] S4, the first laser strengthening component is activated, and the first focused pulsed laser beam irradiates the aluminum alloy surface to be strengthened to perform laser shock strengthening without absorption layer.

[0027] S5, start the walking mechanism, the first focused pulsed laser beam moves forward along the length of the aluminum alloy to be strengthened to complete the laser shock strengthening of the aluminum alloy surface without absorption layer, and at the same time the coating mechanism presses the absorption layer roll film tightly and adheres it to the aluminum alloy surface that has been laser shock strengthened without absorption layer.

[0028] S6, activate the second pulse laser, and the second focused pulse laser beam irradiates the aluminum alloy surface covered with an absorption layer film to perform laser shock strengthening with an absorption layer.

[0029] S7, the absorbent layer film applied to the aluminum alloy surface is rolled up again by the coating mechanism after being strengthened by laser shock with the absorbent layer, thus obtaining a corrosion-resistant layer that has been strengthened once without the absorbent layer and once with the absorbent layer.

[0030] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a device and method for preparing an aluminum alloy corrosion-resistant layer based on laser shock peening, which has the following beneficial effects:

[0031] 1. This invention overcomes the limitations of single laser shock peening with or without an absorption layer. By using this invention, laser shock peening without an absorption layer and laser shock peening with an absorption layer can be performed sequentially. This not only obtains a micron-thick and dense alumina oxide film to protect the aluminum substrate, but also significantly improves the corrosion resistance of aluminum alloys from multiple aspects by increasing the uniformity of corrosion potential of the aluminum substrate, refining grains, generating high-density dislocations and a large residual compressive stress field.

[0032] 2. The absorbent layer roll film of the present invention can be unwound, coated and rewound synchronously with the movement of the traveling mechanism through the coating mechanism, making the absorbent layer roll film easy to unwound and retract and saving manpower.

[0033] 3. The device designed in this invention has a simple structure and is highly operable. The preparation method provided can prepare a high-quality corrosion-resistant layer without the need for additional chemical reagents, and is low in cost and environmentally friendly.

[0034] 4. This invention is applicable to large plate-shaped aluminum alloy components. During the movement of the walking mechanism, laser shock strengthening with and without an absorption layer can be completed sequentially, resulting in high production efficiency. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0036] Figure 1 This invention provides a schematic diagram of a device for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening.

[0037] Figure 2 This is a schematic diagram of the motion of the first pulse laser spot in this invention.

[0038] Figure 3 This is a schematic diagram of the motion of the second pulse laser spot in this invention.

[0039] Figure 4This is a schematic diagram of laser shock peening without an absorption layer in this invention.

[0040] Figure 5 This is a schematic diagram of laser shock peening with an absorption layer in this invention.

[0041] Figure 6 This is a scanning electron microscope image of an aluminum alloy cross-section after undergoing laser shock peening without an absorption layer, as described in Embodiment 1 of the present invention.

[0042] Figure 7 These are scanning electron microscope images of the surface morphology of the aluminum alloy before and after a single laser shock peening process without an absorption layer, as shown in Embodiment 1 of the present invention.

[0043] Figure 8 The image shows the surface morphology of the dense alumina oxide film prepared on the surface of an aluminum alloy using the apparatus and method provided by the present invention in Embodiment 1 of the present invention.

[0044] Figure 9 This is the distribution of residual stress on the surface of the aluminum alloy in Embodiment 1 of the present invention.

[0045] Figure 10 The polarization curves of aluminum alloys with corrosion-resistant layers prepared using the apparatus and method provided by this invention are compared with those of unreinforced aluminum alloys.

[0046] In the diagram: 1. Walking mechanism, 11. Top plate, 12. Support component, 13. Connecting back plate, 14. Walking wheels.

[0047] 2. First laser enhancement component; 21. First pulsed laser; 22. First reflector; 23. First galvanometer laser head; 231. First focused pulsed laser beam; 2311. First pulsed laser spot;

[0048] 3. Second laser enhancement component; 31. Second pulsed laser; 32. Second reflector; 33. Second galvanometer laser head; 331. Second focused pulsed laser beam; 3311. Second pulsed laser spot;

[0049] 4. Coating mechanism; 41. Output roller; 42. Pressure roller; 43. Recycling roller;

[0050] 5. Absorbent layer roll film;

[0051] 6. Spraying mechanism; 61. Water storage tank; 62. Water supply pipe; 63. First nozzle; 64. Second nozzle; 631. First constraint layer; 641. Second constraint layer;

[0052] 7. Aluminum alloy to be strengthened;

[0053] 8. Wiper blade. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0056] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0057] Please see Figures 1-5 This invention discloses an apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening, comprising:

[0058] Walking mechanism 1, which can travel along the length of the aluminum alloy 7 to be strengthened on its surface. Figure 1 The direction of the middle arrow indicates the direction of travel of the walking mechanism 1 during laser shock peening.

[0059] The laser strengthening mechanism includes a first laser strengthening component 2 and a second laser strengthening component 3; the emitting end of the first laser strengthening component 2 corresponds to the front end of the walking mechanism 1 along its traveling direction, and the emitting end of the second laser strengthening component 3 corresponds to the rear end of the walking mechanism 1 along its traveling direction.

[0060] The coating mechanism 4 is rotatably mounted at the rear end of the walking mechanism 1, and its conveying surface is rolled on the surface of the aluminum alloy 7 to be strengthened below the emitting end of the second laser strengthening component 3.

[0061] Absorbent layer roll film 5, one end of absorbent layer roll film 5 is mounted on the coating mechanism 4, and the other end is conveyed along the conveying surface of the coating mechanism 4.

[0062] The first focused pulsed laser beam emitted from the emitting end of the first laser strengthening component 2 can irradiate the surface of the aluminum alloy 7 to be strengthened to perform laser shock strengthening without absorption layer. As the walking mechanism 1 moves forward, the second focused pulsed laser beam emitted from the emitting end of the second laser strengthening component 3 passes through the absorption layer film 5 and irradiates the surface of the aluminum alloy that has been strengthened by laser shock without absorption layer to perform laser shock strengthening with absorption layer, so as to form a corrosion-resistant layer of aluminum alloy.

[0063] In one specific embodiment, the walking mechanism 1 includes a top plate 11, a support member 12, a connecting back plate 13, and walking wheels 14. The top end of the support member 12 is fixed to the bottom of the top plate 11, and the top end of the connecting back plate 13 is fixed to the bottom of the support member 12. The walking wheels 14 are rotatably mounted on the bottom of the connecting back plate 13, and their rolling surfaces can roll on the surface of the aluminum alloy 7 to be strengthened. The walking wheels 14 can be made of rubber to prevent wear on the aluminum alloy surface.

[0064] In one specific embodiment, a drive mechanism (not shown in the figure) is also provided to drive the walking mechanism 1 to move. The drive mechanism is a robot arm, and the top plate 11 can be clamped at the clamping end of the robot arm. The direction and speed of travel of the walking mechanism 1 are controlled by controlling the movement direction and speed of the robot arm. At the same time, when the robot arm acts on the top plate 11, it can provide downward pressure to ensure that the walking mechanism 1 can roll tightly on the aluminum alloy surface and prevent the walking mechanism 1 from detaching from the aluminum alloy surface, which would affect the adhesion between the absorbent layer roll film 5 and the aluminum alloy surface. In some other embodiments, any other known type of drive mechanism can also be used to drive the walking mechanism 1 to move.

[0065] In one specific embodiment, the first laser enhancement component 2 includes a first pulsed laser 21, a first reflector 22, and a first galvanometer laser head 23. The first reflector 22 is fixed to the front end of the support member 12, and its incident end corresponds to the emitting end of the first pulsed laser 21. The first galvanometer laser head 23 is fixed to the connecting back plate 13 below the first reflector 22, and its receiving end corresponds to the reflecting end of the first reflector 22. See also Figure 1 , Figure 2 and Figure 4 The first pulsed laser beam emitted by the first pulsed laser 21 irradiates the first reflector 22 and is reflected by the first reflector 22 before entering the first galvanometer laser head 23. The first focused pulsed laser beam 231 generated by the first galvanometer laser head 23 irradiates the surface of the aluminum alloy 7 to be strengthened. The first pulsed laser spot 2311 formed by the first focused pulsed laser beam 231 on the surface of the aluminum alloy can be scanned back and forth along the width direction of the aluminum alloy 7 to be strengthened, thereby performing laser shock strengthening of the aluminum alloy surface without absorption layer.

[0066] In one specific embodiment, the second laser enhancement component 3 includes a second pulsed laser 31, a second reflector 32, and a second galvanometer laser head 33. The second pulsed laser 31 is located below the first pulsed laser 21. The second reflector 32, corresponding to the emitting end of the second pulsed laser 31, is fixed to the rear end of the support member 12. The second galvanometer laser head 33, corresponding to the reflecting end of the second reflector 32, is fixed to the connecting back plate 13 below the second reflector 32. See also... Figure 1 , Figure 3 and Figure 5 The second pulsed laser beam emitted by the second pulsed laser 31 irradiates the second reflector 32 and is reflected by the second reflector 32 before entering the second galvanometer laser head 33. The second focused pulsed laser beam 331 generated by the second galvanometer laser head 33 passes through the absorption layer film 5 at the corresponding conveying surface and irradiates the aluminum alloy surface that has been laser-strengthened without an absorption layer. The second pulsed laser spot 3311 formed by the second focused pulsed laser beam 331 on the aluminum alloy surface can scan back and forth along the width direction of the aluminum alloy 7 to be strengthened, and perform laser-strengthened with an absorption layer on the aluminum alloy surface that has been laser-strengthened without an absorption layer.

[0067] In one specific embodiment, both the first reflector 22 and the second reflector 32 are laser total reflection mirrors.

[0068] In one specific embodiment, the energy of the first pulsed laser beam emitted by the first pulsed laser 21 is greater than the energy of the second pulsed laser beam emitted by the second pulsed laser 31.

[0069] In one specific embodiment, the coating mechanism 4 includes an output wheel 41, a conveying assembly, and a take-up wheel 43. The output wheel 41 is rotatably mounted in the middle of the connecting back plate 13 and has a built-in driver for driving its rotation. The conveying assembly is rotatably mounted on the bottom of the connecting back plate 13 corresponding to the laser head of the second galvanometer. The take-up wheel 43 is rotatably mounted on the connecting back plate 13 above the conveying assembly and also has a built-in driver for driving its rotation. One end of the absorbent layer roll film 5 is wound onto the output wheel 41, and the other end can extend along the conveying surface of the conveying assembly and be wound onto the take-up wheel 43. The coating mechanism 4 realizes the synchronous unwinding, coating, and take-up of the absorbent layer roll film 5 during the movement of the traveling mechanism 1, which is convenient, fast, and efficient.

[0070] The conveying assembly includes multiple pressure rollers 42 arranged at intervals along the length of the aluminum alloy 7 to be strengthened and rotatably connected to the bottom rear end of the connecting back plate 13. The lower end of each pressure roller 42 is a conveying surface. The multiple pressure rollers 42 expand and press the absorbent layer roll film 5 to ensure that it can be tightly adhered to the aluminum alloy surface.

[0071] In one specific embodiment, two pressure rollers 42 are provided and installed at the rear end of the connecting back plate 13. They can be used to transport the absorbent layer roll film 5 and also for movement, making the overall structure of the device compact and easy to operate.

[0072] In one specific embodiment, the pressure roller 42 may be a rubber roller to prevent damage to the absorbent layer roll film 5.

[0073] In one specific embodiment, a water spraying mechanism 6 is also provided. The water spraying mechanism 6 includes a water storage tank 61, a water supply pipe 62, a first nozzle 63, and a second nozzle 64. The water storage tank 61 is provided with a water outlet. The water inlet end of the water supply pipe 62 is connected to the water outlet. The first nozzle 63 is fixed on the connecting back plate 13 below the first galvanometer laser head 23. Its water inlet end is connected to the water supply pipe 62, and its water outlet end corresponds to the aluminum alloy surface below the first galvanometer laser head 23, so as to form a first constraint layer 631 on the surface of the aluminum alloy 7 to be strengthened below the first galvanometer laser head 23. The second nozzle 64 is fixed on the connecting back plate 13 below the second galvanometer laser head 33. Its water inlet end is connected to the water supply pipe 62, and its water outlet end corresponds to the upper surface of the absorption layer roll film 5 below the second galvanometer laser head 33, so as to form a second constraint layer 641 on the upper surface of the absorption layer roll film 5 below the second galvanometer laser head 33. Both the first nozzle 63 and the second nozzle 64 can be adjustable-angle nozzles of any known type. The nozzle angles are adjusted to create a stable, flowing water layer on the aluminum alloy surface with and without the absorption layer, serving as a corresponding constraint layer.

[0074] In one specific embodiment, a plurality of squeegees 8 are also provided. These squeegees 8 are spaced apart along the length of the aluminum alloy 7 to be strengthened and installed at the bottom of the connecting back plate 13 between the first galvanometer laser head 23 and the second galvanometer laser head 33. The scraping end of each squeegee 8 can abut against the surface of the aluminum alloy 7 to be strengthened, used to clean the water layer on the aluminum alloy surface after laser shock strengthening without an absorption layer, facilitating the laying of the absorption layer roll film 5. The squeegees 8 are rubber squeegees to prevent damage to the aluminum alloy surface after laser shock strengthening without an absorption layer.

[0075] In one specific embodiment, the absorbent layer roll film 5 is made of black tape, which is low in cost and easy to lay and recycle.

[0076] A method for preparing a corrosion-resistant layer on aluminum alloy based on laser shock peening includes the following steps:

[0077] S1, cleans oil stains on the surface of aluminum alloy to be strengthened.

[0078] Specifically, use organic solvents such as acetone and alcohol to remove oil stains from the surface of the aluminum alloy to be strengthened.

[0079] S2, assemble the absorbent layer roll film onto the coating mechanism.

[0080] Specifically, the black tape roll is installed on the conveyor wheel, and the conveyor wheel is started to send the black tape to the two pressure rollers 42. The black tape is tightened by the two pressure rollers 42 and further guided to the recycling wheel 43 for fixing.

[0081] The black tape has a thickness of 0.2–0.8 mm and a width 4–6 mm greater than the scanning width of the first galvanometer laser head 23 and the second galvanometer laser head 33. The pressure roller 42 is 5–10 mm wider than the black tape.

[0082] S3. Place the adjusted walking mechanism on the aluminum alloy to be strengthened to ensure that the absorbent layer roll film can be tightly adhered to the aluminum alloy surface by the conveying surface of the coating mechanism.

[0083] Specifically, the adjusted walking mechanism is placed on the cleaned aluminum alloy to be strengthened, so that the walking wheel 14 and the pressure roller 42 are in close contact with the aluminum alloy surface, ensuring that the black tape can be tightly adhered to the aluminum alloy surface as the pressure roller 42 rotates.

[0084] S4, the first laser strengthening component is activated, and the first pulsed laser beam irradiates the surface of the aluminum alloy to be strengthened to perform laser shock strengthening without absorption layer.

[0085] Specifically, the water spray mechanism 6 is first activated, allowing a stable water flow to be delivered through the water supply pipe 62 to the first nozzle 63 and the second nozzle 64. The nozzle angle is adjusted to form a stable, flowing water layer of 1-2 mm thickness on the aluminum alloy surface, serving as the first constraint layer 631 and the second constraint layer 641 required for laser shock peening. Then, the first pulse laser 21 is activated, generating a high-energy first pulse laser beam with an energy of 30-50 J arranged along the direction of travel at a frequency of 10-25 Hz. After the first reflector 22 changes the propagation direction, the beam enters the first galvanometer laser head 23, forming a first focused pulse laser beam 231. This beam irradiates the aluminum alloy surface covered only by the first constraint layer 631, forming a circular high-energy first pulse laser spot 2311 with a diameter of 5-10 mm. The first galvanometer laser head 23 is then activated, causing the first pulse laser spot 2311 to scan the aluminum alloy surface along its width direction at a speed of 10-50 mm / s, with a scanning width of 10-50 mm.

[0086] S5, start the walking mechanism 1, the first focused pulsed laser beam 231 moves forward along the length direction of the aluminum alloy to be strengthened to complete the laser shock strengthening of the aluminum alloy surface without absorption layer, and at the same time the coating mechanism presses the absorption layer roll film tightly and adheres it to the aluminum alloy surface that has been laser shock strengthened without absorption layer.

[0087] Specifically, the walking mechanism 1 is activated and moves in steps according to the scanning speed and diameter of the first pulse laser spot 2311. After the first pulse laser spot 2311 completes one scan, the walking mechanism 1 moves forward 1-2 mm at a speed of 20-40 mm / s. The first pulse laser spot 2311 moves back and forth along the scanning path in the width direction of the aluminum alloy to be strengthened, and moves forward with the walking mechanism 1 along its traveling direction to complete the 80% overlap rate of the aluminum alloy surface without absorption layer laser shock strengthening. The first pulse laser spot 2311 produces an ablation effect on the surface of the aluminum alloy to be strengthened, forming an alumina oxide film with a thickness of micron. Through surface micro-melting, the segregated alloy elements and precipitated phases are melted into the aluminum matrix, improving the uniformity of the corrosion potential of the aluminum matrix. At the same time, the squeegee 8 scrapes away the surface moisture of the area that has been laser-strengthened without absorption layer along the traveling direction of the walking mechanism 1. Then, the pressure roller 42 presses the black tape tightly against the area that has been laser-strengthened without absorption layer.

[0088] S6, the second pulse laser 31 is activated, and the second focused pulse laser beam irradiates the aluminum alloy surface covered with an absorption layer film to perform laser shock irradiation strengthening with an absorption layer.

[0089] Specifically, the second pulse laser 31 is activated to generate a low-energy second pulse laser beam with an energy of 10-15 J, arranged along the length direction of the aluminum alloy to be strengthened at a frequency of 10-25 Hz. The beam's propagation direction is changed by the second reflector 32 and it enters the second galvanometer laser head 33, forming a second focused pulse laser beam 331 that irradiates the aluminum alloy surface covered by the first constraint layer 631 and black tape, forming a second pulse laser spot 3311 with a diameter of 2-4 mm. The second galvanometer laser head 33 is then activated, controlling the second pulse laser spot 3311 to scan along the width direction of the aluminum alloy to be strengthened at a speed of 10-50 mm / s, ensuring that the second pulse laser spot 3331 is aligned with the first... The first pulse laser spot 2331 can simultaneously complete one line scan, and the scanning width of the second pulse laser spot is 10-50mm. After the second pulse laser spot 3331 completes one line scan, it moves forward 1-2mm at a speed of 20-40mm / s with the walking mechanism 1. The second pulse laser spot 3331 completes the 50% overlap rate absorption layer laser shock strengthening of the aluminum alloy surface by reciprocating along the width direction of the aluminum alloy to be strengthened and moving forward along the length direction of the aluminum alloy to be strengthened. This produces significant plastic deformation on the aluminum alloy surface, compacts the alumina oxide film, increases its density, promotes grain refinement in the near-surface area, increases dislocation density, and forms a large value residual compressive stress layer.

[0090] S7, the absorbent layer film applied to the aluminum alloy surface is rolled up again by the coating mechanism after being strengthened by laser shock with the absorbent layer, thus obtaining a corrosion-resistant layer that has been strengthened once without the absorbent layer and once with the absorbent layer.

[0091] Specifically, the black tape applied to the aluminum alloy surface is guided by the pressure roller 42 after being strengthened by laser shock with an absorption layer. The recycling roller 43 rotates to roll up the used black tape, thus obtaining a corrosion-resistant layer that has undergone one strengthening without an absorption layer and one strengthening with an absorption layer.

[0092] The principle of the corrosion-resistant layer prepared by this invention is as follows: the presence of precipitates and element segregation on the surface of aluminum alloys leads to uneven corrosion potential. The naturally formed Al2O3 oxide film is too thin, and in a corrosive environment, after the Al2O3 oxide film ruptures, the element segregation areas or precipitates will form galvanic cells with the aluminum matrix, resulting in severe corrosion. In this invention, the first galvanometer laser head 23 and the second galvanometer laser head 33 fixed on the traveling mechanism 1 can move forward simultaneously, sequentially performing non-absorbent layer laser shock blasting and absorbent layer laser shock blasting on the surface of the aluminum alloy to be strengthened. As the traveling mechanism 1 moves, at its forward position in the traveling direction, the first focused pulsed laser beam 231 performs high-overlap rate non-absorbent layer laser shock blasting on the aluminum alloy surface. The high-energy first focused pulsed laser beam's thermal effect ablates the surface of the aluminum alloy to be strengthened, forming an Al2O3 oxide film of a certain thickness and generating surface micro-melting, promoting the melting of segregated alloying elements and precipitates into the aluminum matrix. The water layer on the surface of the area where non-absorbent layer laser shock blasting has been completed is removed by the scraper 8 and further pressed by the pressure roller 42. A layer of black tape is tightly covered as an absorption layer. At a position slightly behind the travel direction of the traveling mechanism 1, a low-energy second-focused pulsed laser beam 3311 is used to perform laser shock strengthening on the aluminum alloy surface with an absorption layer. Due to the protection of the black tape, the thermal effect of the laser is negligible. The plasma explosion shock wave generated by the second-focused pulsed laser beam further induces plastic deformation in the area that has been laser-strengthened without an absorption layer, compacting the Al2O3 oxide film to increase its density and inducing violent dislocation movement, thereby generating grain refinement, high-density dislocations, and a high-amplitude residual compressive stress field. The near-surface of the strengthened aluminum alloy forms a corrosion-resistant layer composed of Al2O3 oxide film + grain refinement layer + high-density dislocation layer + high-amplitude residual stress field, which significantly improves the corrosion resistance of the aluminum alloy.

[0093] Example 1:

[0094] In this embodiment, an 8mm thick 2219 aluminum alloy surface is prepared with an etched layer. First, alcohol is used to remove oil stains from the surface of the aluminum alloy to be strengthened. A 0.5mm thick and 55mm wide black tape is assembled onto the conveyor wheel 41. The conveyor wheel 41 is started to send the black tape to two 65mm wide pressure rollers 42 for tensioning. The tape is then guided to the recycling wheel 43 and fixed.

[0095] Place the adjusted walking mechanism 1 on the aluminum alloy to be strengthened, so that the walking wheel 14 and the pressure roller 42 are in close contact with the aluminum alloy surface, ensuring that the black tape can be tightly adhered to the aluminum alloy surface as the pressure roller 42 rotates.

[0096] Start the water storage tank 61, and a stable water flow is delivered to the first nozzle 63 and the second nozzle 64 through the water supply pipe 62. Adjust the nozzle angle to form a stable 1mm thick water layer on the aluminum alloy surface, which serves as the first constraint layer 631 and the second constraint layer 641.

[0097] The first pulse laser 21 is activated to generate a high-energy first pulse laser beam with an energy of 40J at a frequency of 25Hz. The beam is then redirected by the first reflector and enters the first galvanometer laser head 23, forming a first focused pulse laser beam 231 that irradiates the aluminum alloy surface covered only by a water layer, forming a circular first pulse laser spot 2331 with a diameter of 10mm. The first galvanometer laser head 23 is then activated to control the first pulse laser spot 2331 to reciprocate along the width direction of the aluminum alloy to be strengthened at a speed of 50mm / s. The scanning path width of the first pulse laser spot 2331 is 50mm.

[0098] The walking mechanism 1 is activated, and it moves in steps according to the scanning speed and spot diameter of the first galvanometer laser head 23. After the first pulse laser spot 2331 completes one scan, the walking mechanism 1 moves forward 2mm at a speed of 40mm / s. The first pulse laser spot 2331 completes 80% overlap laser shock strengthening of the aluminum alloy surface without absorption layer by reciprocating along the scanning path of the first pulse laser spot along the width direction of the aluminum alloy to be strengthened and moving forward with the walking mechanism 1. The high-energy laser produces an ablation effect on the surface of the aluminum alloy to be strengthened, forming an Al2O3 oxide film with a thickness of micrometers. Through surface micro-melting, the segregated alloy elements and precipitated phases are fused into the aluminum matrix, improving the uniformity of the corrosion potential of the aluminum matrix. The squeegee 8 scrapes away the surface moisture of the area laser shock strengthened without absorption layer along the traveling direction, and then the two pressure rollers 42 press the black tape tightly against the area laser shock strengthened without absorption layer.

[0099] The second pulse laser 31 is activated to generate a low-energy second pulse laser beam with an energy of 10J at a frequency of 25Hz. The beam's propagation direction is changed by the second laser reflector and it enters the second galvanometer laser head 33, forming a second focused pulse laser beam 331 that irradiates the aluminum alloy surface covered by the second constraint layer 641 and black tape, forming a second pulse laser spot 3311 with a diameter of 4mm. The second galvanometer laser head 33 is then activated, controlling the second pulse laser spot 3311 to reciprocate along its scanning path at a speed of 50mm / s, ensuring that the second pulse laser spot 3311 and the first pulse laser spot 2331 can complete a single scan synchronously. The scanning path of the second pulse laser spot 3311 reciprocates along the width direction of the aluminum alloy to be strengthened. The second pulse laser spot 3311, with a width of 50 mm, completes one scan. After the second pulse laser spot 3311 completes one scan, it moves forward 2 mm at a speed of 40 mm / s with the walking mechanism 1. The second pulse laser spot 3311 completes the 50% overlap of the aluminum alloy surface with the absorption layer laser shock strengthening by reciprocating along the scanning path of the second pulse laser spot and moving forward with the walking mechanism 1. This produces significant plastic deformation on the aluminum alloy surface, compacts the Al2O3 oxide film, improves its density, promotes grain refinement in the near-surface area, increases dislocation density, and forms a large residual compressive stress field. The black tape attached to the aluminum alloy surface is wound up by the recycling wheel 43 after the absorption layer laser shock strengthening, thus obtaining a corrosion-resistant layer that has undergone one non-absorption layer laser shock strengthening and one absorption layer laser shock strengthening.

[0100] Figure 6 The image shows a scanning electron microscope image of the near-surface section of an aluminum alloy after a single laser shock peening process without an absorption layer. It can be seen that a complete micron-sized Al2O3 oxide film has been formed on the surface of the aluminum alloy to protect the aluminum alloy substrate.

[0101] Figure 7 The results show that the unevenly distributed Cu-rich precipitates on the surface of the aluminum alloy before strengthening completely disappeared after a single laser shock strengthening without an absorption layer, and the surface of the aluminum alloy was covered by a poorly dense Al2O3 oxide film.

[0102] Figure 8 The results show that after a poorly dense Al2O3 oxide film is first subjected to laser shock peening without an absorption layer, the porosity is reduced and the density is increased after a second laser shock peening with an absorption layer.

[0103] Figure 9The results show that the unstrengthened aluminum alloy surface has a residual tensile stress of +47MPa. After one laser shock strengthening without an absorption layer in the corrosion-resistant layer preparation method provided by the present invention, only a residual compressive stress of -61MPa is generated due to the laser thermal effect. After another laser shock strengthening with an absorption layer, a large residual compressive stress of -216MPa can be obtained.

[0104] Figure 10 The polarization curves of unstrengthened 2219 aluminum alloy and 2219 aluminum alloy with a corrosion-resistant layer prepared by the apparatus and method provided by the present invention in 3.5% NaCl aqueous solution are shown. It can be seen that the corrosion potential of the aluminum alloy is significantly increased and the corrosion current is significantly decreased after the corrosion-resistant layer is prepared, indicating that the corrosion resistance of the aluminum alloy is significantly improved.

[0105] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0106] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening, characterized in that, include: The walking mechanism (1) can travel along the length of the aluminum alloy (7) to be strengthened on its surface; The laser strengthening mechanism includes a first laser strengthening component (2) and a second laser strengthening component (3); the emitting end of the first laser strengthening component (2) corresponds to the front end of the walking mechanism (1) along its traveling direction, and the emitting end of the second laser strengthening component (3) corresponds to the rear end of the walking mechanism (1) along its traveling direction. A coating mechanism (4) is rotatably mounted on the rear end of the walking mechanism (1), and its conveying surface rolls on the surface of the aluminum alloy (7) to be strengthened below the emitting end of the second laser strengthening component (3). Absorbent layer roll film (5), one end of which is mounted on the coating mechanism (4) and the other end is conveyed along the conveying surface of the coating mechanism (4); The first focused pulsed laser beam emitted from the emitting end of the first laser strengthening component (2) can irradiate the surface of the aluminum alloy (7) to be strengthened to perform laser shock strengthening without absorption layer. As the walking mechanism (1) moves forward, the second focused pulsed laser beam emitted from the emitting end of the second laser strengthening component (3) passes through the absorption layer film (5) and irradiates the surface of the aluminum alloy that has been strengthened by laser shock without absorption layer to perform laser shock strengthening with absorption layer, so as to form a corrosion resistant layer of aluminum alloy.

2. The apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening as described in claim 1, characterized in that, The walking mechanism (1) includes a top plate (11), a support member (12), a connecting back plate (13), and a walking wheel (14). The top of the support member (12) is fixed to the bottom of the top plate (11), the top of the connecting back plate (13) is fixed to the bottom of the support member (12), and the walking wheel (14) is rotatably mounted on the bottom of the connecting back plate (13) and its rolling surface can roll on the surface of the aluminum alloy (7) to be strengthened.

3. The apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening as described in claim 2, characterized in that, The first laser strengthening component (2) includes a first pulse laser (21), a first reflector (22) and a first galvanometer laser head (23). The first reflector (22) is fixed to the front end of the support (12), and its incident end corresponds to the emitting end of the first pulse laser (21). The first galvanometer laser head (23) is fixed on the connecting back plate (13) below the first reflector (22), and its receiving end corresponds to the reflecting end of the first reflector (22). The first focused pulse laser beam (231) emitted by the first galvanometer laser head (23) can reciprocate along the length direction of the aluminum alloy (7) to be strengthened on its surface.

4. The apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening as described in claim 3, characterized in that, The second laser strengthening component (3) includes a second pulse laser (31), a second reflector (32), and a second galvanometer laser head (33). The second pulse laser (31) is placed below the first pulse laser (21). The second reflector (32) is fixed to the rear end of the support member (12), and its incident end corresponds to the emitting end of the second pulse laser (31). The second galvanometer laser head (33) is fixed on the connecting back plate (13) below the second reflector (32), and its receiving end corresponds to the reflecting end of the second reflector (32). The second focused pulse laser beam (331) emitted by the second galvanometer laser head (33) can pass through the absorption layer film (5) at the corresponding conveying surface and scan back and forth on the surface of the aluminum alloy (7) to be strengthened along the width direction.

5. The apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening as described in claim 4, characterized in that, The energy of the first pulsed laser beam emitted by the first pulsed laser (21) is greater than the energy of the second pulsed laser beam emitted by the second pulsed laser (31).

6. The apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening as described in claim 5, characterized in that, The coating mechanism (4) includes an output wheel (41), a conveying assembly, and a recovery wheel (43). The output wheel (41) is rotatably mounted on the rear end of the connecting back plate (13). The conveying assembly is rotatably mounted on the bottom of the connecting back plate (13) below the second galvanometer laser head (33). The recovery wheel (43) is rotatably mounted on the connecting back plate (13) above the conveying assembly. One end of the absorption layer roll film (5) is wound on the output wheel (41), and the other end can extend along the conveying surface of the conveying assembly and be wound on the recovery wheel (43).

7. The apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening as described in claim 6, characterized in that, The conveying assembly includes a plurality of pressure rollers (42) spaced apart along the length of the aluminum alloy (7) to be strengthened and rotatably connected to the bottom rear end of the connecting back plate (13), with the lower end of each pressure roller (42) being the conveying surface.

8. The apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening as described in claim 7, characterized in that, It also includes a water spraying mechanism (6), which comprises a water storage tank (61), a water supply pipe (62), a first nozzle (63), and a second nozzle (64). The water storage tank (61) has an outlet, and the inlet end of the water supply pipe (62) is connected to the outlet. The first nozzle (63) is fixed on the connecting back plate (13) below the first galvanometer laser head (23), and its inlet end is connected to the water supply pipe (62). Its outlet end corresponds to the aluminum alloy surface below the first galvanometer laser head (23). A first constraint layer (631) is formed on the surface of the aluminum alloy (7) to be strengthened below the first galvanometer laser head (23); the second nozzle (64) is fixed on the connecting back plate (13) below the second galvanometer laser head (33), its water inlet end is connected to the water supply pipe (62), and its water outlet end corresponds to the upper surface of the absorption layer roll film (5) below the second galvanometer laser head (33), so as to form a second constraint layer (641) on the upper surface of the absorption layer roll film (5) below the second galvanometer laser head (33).

9. The apparatus for preparing a corrosion-resistant aluminum alloy layer based on laser shock peening as described in claim 8, characterized in that, It is also provided with multiple wiper blades (8), which are arranged at intervals along the length direction of the aluminum alloy (7) to be strengthened and connected to the bottom of the connecting back plate (13) between the first galvanometer laser head (23) and the second galvanometer laser head (33). The scraping end of each wiper blade (8) can abut against the surface of the aluminum alloy (7) to be strengthened.

10. A method for preparing a corrosion-resistant layer of aluminum alloy based on laser shock peening, characterized in that, Using the laser shock peening strengthening aluminum alloy corrosion-resistant layer preparation apparatus according to any one of claims 1 to 9, Includes the following steps: S1, clean oil stains on the surface of the aluminum alloy to be strengthened; S2, Assemble the absorbent layer roll film onto the coating mechanism; S3, place the adjusted walking mechanism on the aluminum alloy to be strengthened to ensure that the absorbent layer roll film can be tightly adhered to the aluminum alloy surface along with the conveying surface of the coating mechanism. S4, the first laser strengthening component is activated, and the first focused pulsed laser beam irradiates the aluminum alloy surface to be strengthened to perform laser shock strengthening without absorption layer. S5, start the walking mechanism, the first focused pulsed laser beam moves forward along the length of the aluminum alloy to be strengthened to complete the laser shock strengthening of the aluminum alloy surface without absorption layer, and at the same time the coating mechanism presses the absorption layer roll film tightly and adheres it to the aluminum alloy surface that has been laser shock strengthened without absorption layer. S6, activate the second pulse laser, and the second focused pulse laser beam irradiates the aluminum alloy surface covered with an absorption layer film to perform laser shock strengthening with an absorption layer. S7, the absorbent layer film applied to the aluminum alloy surface is rolled up again by the coating mechanism after being strengthened by laser shock with the absorbent layer, thus obtaining a corrosion-resistant layer that has been strengthened once without the absorbent layer and once with the absorbent layer.

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