Laser shock pretreatment method, system, medium and equipment for improving spraying performance

Abstract

The invention relates to a laser shock pretreatment method, system, medium and equipment for improving spraying performance, in the method, absolute ethyl alcohol is used for cleaning the surface of a metal matrix so as to remove oil stains, oxide skin and impurities on the surface, the surface of the metal matrix is evenly coated with an absorption layer, the absorption layer is covered with a water restraint layer, and the water restraint layer is used for restraining the surface of the metal matrix. Performing laser shock peening treatment on the metal matrix to form a strengthened surface layer with residual compressive stress and microstructure regulation and control; after the laser shock peening treatment is completed, the residual absorbing layer on the surface of the metal matrix is cleaned away, and drying treatment is carried out; and performing metal spraying treatment on the surface of the dried metal matrix to obtain the metal coating.

Description

Technical Field

[0001] This invention relates to the field of metal spraying technology, and in particular to a laser shock pretreatment method, system, medium, and equipment for improving spraying performance. Background Technology

[0002] Metal thermal spraying, as a commonly used surface strengthening method, is widely applied in aerospace, energy, and automotive fields. The thermal spray coating typically bonds to the substrate via mechanical interlocking; therefore, substrate surface pretreatment is crucial to the coating's bonding strength and fatigue performance. Common pretreatment methods include sandblasting, grooving, thread cutting, EDM roughening, chemical cleaning, water jetting, dry ice blasting, and laser pretreatment. While these methods increase surface roughness to facilitate mechanical interlocking, they also have significant drawbacks. For example, the rough surface and stress concentration areas generated by traditional sandblasting can easily become fatigue crack initiation sites, leading to rapid crack initiation and propagation, significantly reducing the fatigue strength of the coating substrate. Furthermore, the thermal expansion differences during thermal spraying often generate residual tensile stress at the interface, accelerating crack propagation and further reducing fatigue life. Especially for thick-layer spraying (coating thickness reaching millimeters), existing pretreatment methods have limited effectiveness, often resulting in poor bonding strength and impact resistance. In addition, chemical pretreatment causes environmental pollution, while mechanical roughening may excessively damage the substrate. Therefore, a new pretreatment technology is needed to improve fatigue performance while maintaining or enhancing bond strength, and to avoid the contamination and complex process problems of traditional methods.

[0003] The information disclosed in the background section is only for enhancing the understanding of the background of this invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] This invention provides a laser shock pretreatment method, system, medium, and equipment for improving spraying performance, which significantly improves coating performance by performing laser shock pretreatment on the substrate before thermal spraying.

[0005] A laser shock pretreatment method for improving coating performance includes: S1: Clean the surface of the metal substrate with anhydrous ethanol to remove surface oil, oxide scale, and impurities. S2: A uniform absorption layer is coated on the surface of the metal substrate, and a water confinement layer is covered on top of the absorption layer. The metal substrate is subjected to laser shock strengthening treatment to form a strengthened surface layer with residual compressive stress and microstructure regulation. S3: After the laser shock hardening treatment is completed, the residual absorption layer on the surface of the metal substrate is cleaned off and then dried. S4: A metal coating is obtained by performing metal spraying on the dried metal substrate surface.

[0006] The laser shock pretreatment method for improving coating performance further includes, S5: After spraying, allow the coating to cool naturally before conducting quality checks and post-treatment.

[0007] In the laser shock pretreatment method for improving coating performance, in step S2, Set laser parameters and scanning path, and use overlap ratio to ensure no blind spots in coverage. The area to be treated is irradiated with a high-energy pulsed laser. Multiple laser scans are performed, gradually scanning the area to be scanned along a set route, to form a continuous and uniform enhanced surface layer.

[0008] In the laser shock pretreatment method for improving spraying performance, the laser shock strengthening uses a high-energy pulsed laser with a laser pulse width in the nanosecond range, an energy density controlled at 2~10 J / cm², a scanning speed of 0.5~2 m / s, and a scanning path overlap rate of 20%~50%.

[0009] In the laser shock pretreatment method for improving spraying performance, the absorption layer is one of black paint, graphite or silicon carbide coating, with a thickness of 10~100 μm; the water confinement layer is a deionized water layer with a thickness of 1~3 mm.

[0010] In the laser shock pretreatment method for improving spraying performance, the laser shock strengthening introduces a residual compressive stress depth of 50~300 μm on the substrate surface, increases the surface hardness by 10%~30%, and refines the grain size to the nanoscale.

[0011] In the laser shock pretreatment method for improving spraying performance, the metal spraying treatment adopts plasma spraying, high-speed flame spraying or supersonic spraying, the spraying material is metal or metal-ceramic composite powder, and the spraying thickness is 0.2~3 mm.

[0012] A system for implementing the method includes: The laser shock peening module includes a high-energy pulsed laser, an absorption layer coating device, a water confinement layer supply device, and a scanning galvanometer. Surface treatment module, used for substrate cleaning, drying and absorption layer removal; The thermal spraying module includes a spray gun, a powder feeding system, and a gas control system. The central control module is used to set laser parameters, spraying parameters, scanning path, and coordinate the collaborative work of various modules. The quality inspection module includes a coating adhesion strength testing device, a residual stress testing device, and a surface morphology analysis device.

[0013] A computer storage medium including computer instructions that, when run on a computer, cause the computer to perform the method.

[0014] An electronic device, the electronic device comprising: Memory, processor, and computer programs stored in memory and executable on the processor, wherein, The processor implements the method when executing the program.

[0015] Compared with existing technologies, this invention has the following advantages: This method can introduce deeper residual compressive stress on the substrate surface, and the uniformly distributed compressive stress firmly presses the coating onto the substrate; at the same time, the surface microstructure generated by laser shock blasting increases the mechanical interlocking area of ​​the coating particles, making the coating difficult to pull off. Compared with traditional sandblasting roughening, the microstructure after laser shock blasting is more conducive to the formation of a stable bond when coating particles impact; in addition, the refined nanocrystalline structure under laser shock blasting improves surface hardness and strength, which is beneficial to the formation of good adhesion between the coating material and the substrate. Attached Figure Description

[0016] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0017] In the attached diagram: Figure 1 This is a flowchart of the laser shock pretreatment method for improving spraying performance in this invention; Figure 2 This is a schematic diagram of the specific process of step 2 in this invention; Figure 3 This is a schematic diagram of the specific process of step 4 in this invention.

[0018] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0019] Specific embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0020] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0021] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0022] like Figures 1 to 3 As shown, the laser shock pretreatment method for improving coating performance includes the following steps: S1: Clean the surface of the metal substrate with anhydrous ethanol to remove surface oil, oxide scale, and impurities. S2: A uniform absorption layer is coated on the surface of the metal substrate, and a water confinement layer is covered on top of the absorption layer. The metal substrate is subjected to laser shock strengthening treatment to form a strengthened surface layer with residual compressive stress and microstructure regulation. S3: After the laser shock hardening treatment is completed, the residual absorption layer on the surface of the metal substrate is cleaned off and then dried. S4: A metal coating is obtained by performing metal spraying on the dried metal substrate surface.

[0023] In a preferred embodiment of the laser shock pretreatment method for improving coating performance, the method further includes: S5: After spraying, allow the coating to cool naturally before conducting quality checks and post-treatment.

[0024] In a preferred embodiment of the laser shock pretreatment method for improving coating performance, in S2, Set laser parameters and scanning path, and use overlap ratio to ensure no blind spots in coverage. The area to be treated is irradiated with a high-energy pulsed laser. Multiple laser scans are performed, gradually scanning the area to be scanned along a set route, to form a continuous and uniform enhanced surface layer.

[0025] In a preferred embodiment of the laser shock pretreatment method for improving spraying performance, the laser shock strengthening uses a high-energy pulsed laser with a laser pulse width in the nanosecond range, an energy density controlled at 2~10 J / cm², a scanning speed of 0.5~2 m / s, and a scanning path overlap rate of 20%~50%.

[0026] In a preferred embodiment of the laser shock pretreatment method for improving spraying performance, the absorption layer is one of black paint, graphite or silicon carbide coating, with a thickness of 10~100 μm; the water confinement layer is a deionized water layer with a thickness of 1~3 mm.

[0027] In a preferred embodiment of the laser shock pretreatment method for improving coating performance, the laser shock strengthening introduces a residual compressive stress depth of 50~300 μm on the substrate surface, increases the surface hardness by 10%~30%, and refines the grain size to the nanoscale.

[0028] In a preferred embodiment of the laser shock pretreatment method for improving spraying performance, the metal spraying treatment adopts plasma spraying, high-speed flame spraying or supersonic spraying, the spraying material is metal or metal-ceramic composite powder, and the spraying thickness is 0.2~3 mm.

[0029] A system for implementing the method includes: The laser shock peening module includes a high-energy pulsed laser, an absorption layer coating device, a water confinement layer supply device, and a scanning galvanometer. Surface treatment module, used for substrate cleaning, drying and absorption layer removal; The thermal spraying module includes a spray gun, a powder feeding system, and a gas control system. The central control module is used to set laser parameters, spraying parameters, scanning path, and coordinate the collaborative work of various modules. The quality inspection module includes a coating adhesion strength testing device, a residual stress testing device, and a surface morphology analysis device.

[0030] A computer storage medium including computer instructions that, when run on a computer, cause the computer to perform the method.

[0031] An electronic device, the electronic device comprising: Memory, processor, and computer programs stored in memory and executable on the processor, wherein, The processor implements the method when executing the program.

[0032] In one embodiment, the method includes, S1: Clean the surface of the sample with anhydrous ethanol to remove surface oil, oxide scale, dust and other contaminants, and ensure that the surface of the laser impact area is uniform and free of impurities.

[0033] S2: Laser shock peening treatment is applied to the surface of the metal substrate; S2.1 A layer of absorbent material is uniformly coated onto a clean and dry metal substrate surface; S2.2 Cover the absorber layer with a water-binding layer; S2.3 Set the laser parameters and scanning path, and use a certain overlap rate to ensure no blind spots in coverage.

[0034] S2.4 Irradiate the area to be treated with a high-energy pulsed laser; S2.5 Multiple laser scans are performed, gradually scanning the area to be scanned along a set route to form a continuous and uniform enhanced surface structure.

[0035] S3: After laser treatment, clean off the absorption layer on the substrate surface, check the surface condition of the substrate, and dry it. S4: Apply metal spraying treatment to the surface that has been laser-strengthened and dried; S4.1 Set appropriate spraying parameters; S4.2 Select a spraying material that is compatible with the substrate and operating conditions, and perform pretreatment such as particle size screening, drying and dehumidification on the powder particles; S4.3 Control the spray gun to perform spraying operations according to the set path and parameters, achieve the required thickness through multiple layers, and monitor the temperature and deposition rate at the same time. S4.4 After spraying, allow the coating to cool naturally or with auxiliary cooling. After cooling, conduct a preliminary quality inspection of the coating.

[0036] S5: After the spraying is completed, conduct quality inspection and post-treatment.

[0037] In conclusion, this is understandable. This method introduces deeper residual compressive stress on the substrate surface, and the uniformly distributed compressive stress firmly presses the coating onto the substrate. Simultaneously, the surface microstructure generated by laser shock blasting increases the mechanical interlocking area of ​​the coating particles, making the coating difficult to pull off. Compared to traditional sandblasting roughening, the microstructure after laser shock blasting is more conducive to the formation of a stable bond when coating particles impact. Furthermore, the refined nanocrystalline structure under laser shock blasting improves surface hardness and strength, which is beneficial for good adhesion between the coating material and the substrate. The introduced residual compressive stress field can effectively close the microcrack initiation on the substrate surface and at the interface, and counteract the residual tensile stress that may be generated during thermal spraying. The compressive stress layer makes it necessary for cracks to open with higher external force, thereby inhibiting crack initiation and early propagation. Traditional sandblasting pretreatment creates a rough, high-stress interface, which easily leads to fatigue cracks, while the lower surface roughness and uniform stress distribution in this method significantly reduce stress concentration. At the microscopic level, due to the increased crack propagation resistance of the grain-refined material, the fracture toughness and fatigue limit of the substrate are improved. The synergistic effect of deep residual compressive stress and refined microstructure can significantly improve the fatigue life of coated parts. The compressive stress layer generated by high strain rate plastic deformation has been proven to significantly extend the fatigue life of materials; specifically, studies have shown that the fatigue life of laser-strengthened titanium alloys can be increased by 3 to 5 times. Furthermore, laser shock treatment has minimal impact on surface roughness, avoiding the large, sharp protrusions and stress concentrations caused by traditional pretreatment, thereby delaying the formation and propagation of fatigue cracks and further improving fatigue strength. This method is entirely physical, requiring no acid pickling or chemical coating, and does not generate toxic waste liquids or polluting gases, meeting green manufacturing requirements. Unlike pre-coated chemical layers that require subsequent cleaning or curing, laser shock can be used directly for spraying without additional heat treatment. The overall process is simple, and the equipment can be integrated online into the spraying production line, achieving integrated pretreatment before spraying, reducing processes while ensuring coating quality.

[0038] Furthermore, this invention performs laser shock peening treatment on the surface of the metal substrate before thermal spraying; a high-energy pulsed laser is used, in conjunction with an absorption layer and a water confinement layer, with the laser energy density, scanning path, and overlap rate set; a strengthened surface layer with residual compressive stress and microstructure regulation is formed. The laser shock generates a high-pressure shock wave on the substrate surface, inducing plastic deformation and forming a high-density dislocation structure, thereby introducing deep residual compressive stress on the surface and subsurface; the high strain rate plastic deformation generated by the laser shock refines the surface grains to the nanoscale, improving surface hardness and strength; without significantly increasing surface roughness, a microstructure conducive to the spreading and embedding of sprayed particles is formed; the surface lattice distortion and dislocation density increase after laser shock treatment enhance the interfacial atomic diffusion ability, which is beneficial to the physical metallurgical bonding between the coating and the substrate. An absorption layer (such as black paint, graphite, or silicon carbide coating) is coated on the substrate surface; a water confinement layer (such as deionized water) is covered above the absorption layer; the laser irradiates the absorption layer through the water confinement layer, generating a plasma shock wave. The absorption layer rapidly vaporizes after absorbing laser energy, generating a plasma explosion and forming a high-intensity shock wave. The water confinement layer restricts the plasma expansion direction, enhancing the shock wave pressure while simultaneously cooling the substrate surface to prevent thermal damage. The water confinement layer reflects some of the laser energy, creating a secondary impact effect and enhancing the shock wave's depth. During processing, the water confinement layer washes away surface debris, keeping the surface clean. The depth and distribution of residual compressive stress are controlled by setting the laser energy density, scanning path, and number of impacts; the residual compressive stress depth is controlled within the range of 50–300 μm. The residual compressive stress closes the microcrack initiation points on the substrate surface, requiring higher external forces to open the cracks. During the thermal spraying cooling process, tensile stress is generated between the coating and the substrate due to the difference in thermal expansion; the compressive stress can partially offset this tensile stress. The compressive stress layer can significantly delay fatigue crack propagation, improving the material's durability under alternating loads. The compressive stress also makes the coating adhere more tightly to the substrate, reducing the tendency for interfacial delamination. Laser shock induced high strain rate plastic deformation leads to grain refinement; the surface grain size is refined from 5~10 μm to 0.5~1.0 μm (nanometer scale). Grain refinement brings about the Hall-Petch effect, increasing surface hardness by 10%~30%; the fine-grained structure has higher yield strength, reducing the rebound of sprayed particles during impact; the fine-grained structure has greater resistance to crack propagation, delaying crack propagation; surface lattice distortion and dislocation density increase, enhancing the interfacial atomic diffusion ability and improving bonding strength. By optimizing laser shock parameters, the surface roughness is controlled within the Ra range of 0.5~3 μm; compared with traditional sandblasting (Ra 5~8 μm), the surface protrusion height is significantly reduced. The sharp protrusions formed by traditional sandblasting are prone to becoming crack initiation sources, while the surface after laser shock treatment is more uniform; the reduction of surface protrusions reduces the probability of fatigue crack initiation; the surface is smoother, the distribution of sprayed particles is more uniform, reducing local accumulation or voids; the coating is smoother, reducing the amount of post-processing work such as grinding and polishing.It does not use polluting processes such as pickling, electroplating, and chemical coating; it can be directly thermally sprayed after laser shock treatment without additional heat treatment; it can be integrated with the spraying equipment on the same production line, and does not use harmful chemicals such as strong acids and alkalis, meeting the requirements of green manufacturing; it eliminates multiple steps such as cleaning, curing, and drying in traditional pretreatment; laser shock and spraying can be integrated online, reducing process changeover time; the treated surface is free of oxidation and pollution, and the spraying bonding is more reliable.

[0039] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of the present invention, and all of these are within the scope of protection of the present invention.

Claims

1. A laser shock pretreatment method for improving coating performance, characterized in that, Includes the following steps: S1: Clean the surface of the metal substrate with anhydrous ethanol to remove surface oil, oxide scale, and impurities. S2: A uniform absorption layer is coated on the surface of the metal substrate, and a water confinement layer is covered on top of the absorption layer. The metal substrate is subjected to laser shock strengthening treatment to form a strengthened surface layer with residual compressive stress and microstructure regulation. S3: After the laser shock hardening treatment is completed, the residual absorption layer on the surface of the metal substrate is cleaned off and then dried. S4: A metal coating is obtained by performing metal spraying on the dried metal substrate surface.

2. The laser shock pretreatment method for improving spraying performance according to claim 1, characterized in that, Preferred options also include, S5: After spraying, allow the coating to cool naturally before conducting quality checks and post-treatment.

3. The laser shock pretreatment method for improving spraying performance according to claim 1, characterized in that, In S2, Set laser parameters and scanning path, and use overlap ratio to ensure no blind spots in coverage. The area to be treated is irradiated with a high-energy pulsed laser. Multiple laser scans are performed, gradually scanning the area to be scanned along a set route, to form a continuous and uniform enhanced surface layer.

4. The laser shock pretreatment method for improving spraying performance according to claim 3, characterized in that, The laser shock enhancement uses a high-energy pulsed laser with a laser pulse width in the nanosecond range, an energy density controlled at 2~10 J / cm², a scanning speed of 0.5~2 m / s, and a scanning path overlap rate of 20%~50%.

5. The laser shock pretreatment method for improving spraying performance according to claim 1, characterized in that, The absorbent layer is one of black paint, graphite, or silicon carbide coating, with a thickness of 10~100 μm; the water-binding layer is a deionized water layer with a thickness of 1~3 mm.

6. The laser shock pretreatment method for improving spraying performance according to claim 1, characterized in that, The laser shock strengthening introduces a residual compressive stress depth of 50~300 μm on the substrate surface, increases the surface hardness by 10%~30%, and refines the grain size to the nanoscale.

7. The laser shock pretreatment method for improving spraying performance according to claim 1, characterized in that, The metal spraying process employs plasma spraying, high-speed flame spraying, or supersonic spraying methods. The spraying material is metal or metal-ceramic composite powder, and the spraying thickness is 0.2~3 mm.

8. A system for implementing the method of any one of claims 1-7, characterized in that, It includes: The laser shock peening module includes a high-energy pulsed laser, an absorption layer coating device, a water confinement layer supply device, and a scanning galvanometer. Surface treatment module, used for substrate cleaning, drying and absorption layer removal; The thermal spraying module includes a spray gun, a powder feeding system, and a gas control system. The central control module is used to set laser parameters, spraying parameters, scanning path, and coordinate the collaborative work of various modules. The quality inspection module includes a coating adhesion strength testing device, a residual stress testing device, and a surface morphology analysis device.

9. A computer storage medium, characterized in that, The storage medium includes computer instructions that, when executed on a computer, cause the computer to perform the method as described in any one of claims 1-7.

10. An electronic device, characterized in that, The electronic device includes: Memory, processor, and computer programs stored in memory and executable on the processor, wherein, When the processor executes the program, it implements the method as described in any one of claims 1-7.

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