Low reflectance high stress copper alloy coating and method of making and use thereof

Abstract

The application discloses a low-reflection and low-stress copper alloy coating and a preparation method and application thereof. A copper-based powder, a solvent, a binder and a dispersant are mixed to obtain a mixed solution, the mixed solution is atomized, sprayed out through a spraying port of the atomized solution and subjected to hot air treatment, and then porous agglomerated particles are obtained; a copper base is subjected to laser etching to form a texture, and then cleaned to obtain a copper base with the texture; the porous agglomerated particles are loaded on the surface of the copper base with the texture through super-high-speed laser cladding to obtain the low-reflection and low-stress copper alloy coating. The application reduces laser dissipation in the super-high-speed laser cladding process by preparing the porous agglomerated particles and pre-preparing the texture on the copper base, realizes full melting of the coating powder, increases the contact area between the copper base and the coating through the texture, enhances the combination between the coating and the copper base, reduces the internal stress of the coating, and then significantly improves the wear resistance and service life of the coating.

Description

Technical Field

[0001] This invention relates to the technical field of coating preparation, specifically to low-reflection, strong-bonding, and low-stress copper alloy coatings, their preparation methods, and applications. Background Technology

[0002] Copper, as an important metallic material, is widely used in electrical industries, industrial manufacturing and machinery, aerospace and other fields due to its excellent electrical and thermal conductivity, corrosion resistance and ductility. However, due to its low hardness and poor wear resistance, copper has a shortened lifespan and requires frequent replacement, especially in friction scenarios (such as bearings and gears). Therefore, copper is often combined with other metallic elements to form composite coatings. Common coating processes include laser cladding, chemical deposition, and electroplating.

[0003] Laser cladding is a surface modification technology that uses high-energy lasers to melt metal powder and form a high-performance coating. Its core advantages lie in its high precision and strong adhesion. The concentrated laser energy results in a very small heat-affected zone, allowing for precise control of the cladding layer thickness (0.1~2mm), making it suitable for repairing complex parts while minimizing deformation of the substrate.

[0004] Laser cladding is divided into ultra-high-speed laser cladding and conventional laser cladding technology. The core advantages of ultra-high-speed laser cladding compared to conventional laser cladding lie in improved efficiency, precision, and material properties: its processing speed can reach 100~500mm / s (compared to 10~50mm / s for conventional methods), and the cladding layer thickness can be precisely controlled to 0.2~10mm. Although the initial surface roughness (Ra) is 5~10µm, slightly higher than some ranges of conventional processes (3.2~8.2µm), the ultra-high-speed cladding layer surface is more uniform, without obvious protrusions or defects, and can achieve a mirror-like effect after simple polishing, reducing subsequent processing steps by 80%. However, because the cladding speed is too fast during ultra-high-speed laser cladding, the melting and diffusion between the coating and the copper substrate are insufficient, resulting in a significant reduction in the bonding strength between the coating and the copper substrate.

[0005] Furthermore, copper has a reflectivity of over 90% for common lasers (such as 1064nm wavelength), resulting in low laser energy utilization and difficulty in forming a stable molten pool. This problem is particularly pronounced in the initial processing stage, easily leading to defects such as spatter, incomplete fusion, and molten pool fluctuations. Secondly, during the cooling process of the coating produced by ultra-high-speed laser cladding, the large temperature gradient within the material causes uneven shrinkage. The outer layer cools and shrinks faster than the inner layer, generating enormous internal stress. When this internal stress exceeds the material's yield strength, cracks will appear in the cladding coating.

[0006] Therefore, how to prepare a coating with better performance based on ultra-high-speed laser cladding technology is a technical problem that needs to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a low-reflection, high-bonding, low-stress copper alloy coating, its preparation method, and its applications. This invention reduces laser dissipation during ultra-high-speed laser cladding by preparing porous agglomerated particles and pre-texturing the copper substrate, allowing for more efficient utilization of laser energy by the coating powder. This efficient energy absorption causes more powder particles to rapidly heat up under the laser, reaching and exceeding their melting point, thus achieving complete melting of the coating powder and forming a metallurgical bond with the copper substrate. This excellent bonding results in a dense internal structure of the coating prepared by this invention, free from obvious pores, cracks, and other defects, providing a solid microstructural foundation for the coating. The textured surface increases the contact area between the copper substrate and the coating, enhancing the bonding between them, reducing internal stress, eliminating morphological defects, and significantly improving the coating's wear resistance and service life. Therefore, this invention provides a coating with high bonding strength and good wear resistance based on ultra-high-speed laser cladding technology.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] The first aspect of this invention is to provide a method for preparing a low-reflection, strong-bonding, low-stress copper alloy coating, comprising the following steps:

[0010] (1) Mix copper-based powder, solvent, binder and dispersant evenly to obtain a mixture. Atomize the mixture and spray it out through the atomizing nozzle. Then, treat the sprayed atomized droplets with hot air to evaporate the solvent and part of the binder and dispersant to obtain porous agglomerated particles.

[0011] (2) The copper substrate is textured by laser etching, cleaned, and the textured copper substrate is obtained;

[0012] (3) The porous agglomerated particles are loaded onto the textured copper substrate surface by ultra-high speed laser cladding to obtain a copper alloy coating with low reflection, strong bonding and low stress.

[0013] As a preferred embodiment, the method for preparing a low-reflection, high-bondage, low-stress copper alloy coating includes the following steps:

[0014] (1) The copper-based powder is pulverized in a QYF-260 air classifier using air jet milling. The pulverized powder is thoroughly mixed with deionized water, binder and dispersant, and then fed into a pressure pump through a pipeline. The mixture is atomized through a nozzle and then passed through a hot air blower to make the atomized droplets evaporate the solvent quickly in the hot air to form porous agglomerated particles. Finally, the dried powder is recovered through a funnel.

[0015] (2) First, grind the surface of the copper substrate using a grinding machine, and then clean the surface of the copper substrate with anhydrous ethanol. Place the prepared copper substrate on the worktable of the laser etching machine for laser etching texture treatment. Finally, clean the debris on the surface of the copper substrate again with anhydrous ethanol.

[0016] (3) Place the textured copper substrate on the worktable, then pour the prepared porous agglomerated particles into the powder feeder and perform ultra-high speed laser cladding to prepare a coating with a smooth surface and no obvious cracks or other defects.

[0017] As a preferred implementation, step (1)

[0018] The copper-based powder has a particle size of 1~5µm, and the copper-based powder can be prepared by air jet milling to obtain copper-based powder with a particle size of 1~5µm; and / or,

[0019] The copper-based powder is selected from CuZrAlCo alloy powder and CuSn. 12 Ni2 alloy powder, CuCrZr alloy powder, CuZrNiAl alloy powder or CuAl 10 At least one of the alloy powders; and / or,

[0020] The solvent is water; and / or,

[0021] The adhesive is at least one of polyethylene wax or terpene resin; and / or,

[0022] The dispersant is at least one of ethyl acetate or isopropanol.

[0023] The porosity of porous agglomerated particles is 0.2%~0.5%.

[0024] As a preferred implementation, step (1)

[0025] The amount of copper-based powder added is 100-200 grams; and / or,

[0026] The amount of solvent added is 200-400 grams; and / or,

[0027] The amount of adhesive added is 1-2 grams; and / or,

[0028] The amount of the dispersant added is 1-2 grams; and / or,

[0029] The size of the atomized droplets is 10~200µm; and / or,

[0030] The hot air temperature for hot air treatment is 150~300°C.

[0031] As a preferred implementation, step (2)

[0032] The texture is a hollow truncated quadrangular groove, wherein the smaller bottom surface of the hollow truncated quadrangular groove is located inside the copper substrate and is referred to as the bottom surface. The bottom surface is square and all corners of the bottom surface are rounded. The initial width of the bottom surface before rounding is 25~50µm, and the radius of the rounded corners after rounding is 5~10µm.

[0033] The larger bottom surface in the hollow truncated quadrangular groove is located on the surface of the copper substrate and is referred to as the upper bottom surface. The upper bottom surface is square and all corners of the upper bottom surface are rounded. The initial width of the upper bottom surface before rounding is 50~80µm, and the radius of the rounded corners after rounding is 10~20µm.

[0034] The depth of the hollow truncated quadrangular groove is 50~80µm; the spacing between the hollow truncated quadrangular grooves is 50~80µm.

[0035] As a preferred implementation, step (2)

[0036] The texture is a hollow triangular prism-shaped groove, wherein the upper and lower bases of the hollow triangular prism-shaped groove are corresponding identical equilateral triangles, and the corners of the upper and lower bases of the equilateral triangles are rounded; the initial side length of the equilateral triangles before rounding is 50~80µm, and the rounded corner radius is 10~15µm; the depth of the hollow triangular prism-shaped groove is 50~80µm; the groove spacing between the hollow triangular prism-shaped grooves is 50~80µm; and / or,

[0037] The texture is in the shape of hollow cylindrical holes and grooves; the diameter of the upper and lower bottom surfaces of the hollow cylindrical holes and grooves is 50~80µm; the depth of the hollow cylindrical holes and grooves is 50~80µm; and the spacing between the hollow cylindrical holes and grooves is 50~80µm.

[0038] As a preferred implementation, step (2)

[0039] In the laser etching process

[0040] The distance between the laser head nozzle and the copper substrate is 13~20mm; and / or,

[0041] The laser head speed is 2~5mm / s; and / or,

[0042] The laser head has a frequency of 60~80Hz; and / or,

[0043] Laser power of 1000~2000W, pulse duration of 10~15 microseconds; and / or,

[0044] The laser wavelength is 354~356nm.

[0045] As a preferred implementation, step (3)

[0046] The ultra-high-speed laser cladding uses a laser wavelength of 600-750 nm and a power of 1500-3000 W; and / or,

[0047] The ultra-high-speed laser cladding uses a coaxial powder feeding method, where the powder consists of porous agglomerated particles; the powder feeding rate is set to 1~2 g / min; and / or,

[0048] The distance between the nozzle of the ultra-high-speed laser cladding and the surface of the untextured copper substrate in the textured copper substrate is 10-15 mm; and / or,

[0049] The laser focus of the ultra-high-speed laser cladding adopts a bow-shaped reciprocating pattern; and / or,

[0050] The laser scanning speed of the ultra-high-speed laser cladding is 200mm~350mm / s; and / or,

[0051] The angle between the laser head of the ultra-high-speed laser cladding and the horizontal plane of the copper substrate is 60°~85°.

[0052] A second aspect of the present invention is to provide a low-reflection, strong-bonding, low-stress copper alloy coating prepared by the method described in the first aspect of the present invention.

[0053] In a preferred embodiment, the bonding strength of the low-reflection, high-bond, low-stress copper alloy coating is 300~400MPa;

[0054] The residual stress of the low-reflection, strong-bonded, low-stress copper alloy coating is 50~150MPa.

[0055] The volumetric wear rate of the low-reflectivity, high-bondage, low-stress copper alloy coating is 1.8 × 10⁻⁶. -5 ~ 2.2×10 - 5 mm 3 ·N -1 ·m -1 .

[0056] A third aspect of the present invention is to provide an application of a low-reflection, high-bond, low-stress copper alloy coating prepared by the method described in the first aspect of the present invention in heat dissipation coatings for electronic components, surface treatment of precision aerospace parts, anti-wear coatings for high-end molds, and conductive and wear-resistant components.

[0057] The low-reflection, strong-bonding, and low-stress copper alloy coating prepared by this invention can be used in heat dissipation coatings for electronic components, surface treatment of precision aerospace parts, anti-wear coatings for high-end molds, and conductive wear-resistant components. It can reduce optical signal interference due to its low reflection characteristics, ensure coating stability in complex environments due to its strong bonding force, and avoid substrate deformation due to its low stress advantage, thus meeting the stringent requirements of various fields for coating functionality and reliability.

[0058] This invention reduces laser dissipation during ultra-high-speed laser cladding by preparing porous agglomerated particles and pre-texturing the copper substrate, allowing for more efficient utilization of laser energy by the coating powder. Most of the energy in ultra-high-speed laser cladding acts directly on the powder, thus avoiding damage to the pre-textured substrate surface. This efficient energy absorption causes more powder particles to rapidly heat up under the laser, reaching and exceeding their melting point, thereby achieving complete melting of the coating powder and forming a metallurgical bond with the copper substrate. This excellent bonding results in a dense internal structure of the coating prepared by this invention, free from obvious pores, cracks, and other defects. Furthermore, the presence of texture in the copper substrate increases the contact area between the copper substrate and the coating, enhancing the bonding between them, reducing internal stress, and helping to eliminate morphological defects. This significantly improves the coating's wear resistance and service life. Specifically:

[0059] During ultra-high-speed laser cladding, as porous agglomerated particles are airborne or sprayed onto the textured copper substrate surface, the irregular pits and voids on the particle surface cause some laser light to be reflected when irradiated, while the remaining portion penetrates the porous agglomerated particles through their pores. This allows the particles to absorb more laser energy, thus improving powder melting efficiency and ensuring thorough melting of the coating powder to form a metallurgical bond with the copper substrate. Furthermore, during ultra-high-speed laser cladding, some incident laser light enters pre-prepared textured grooves within the copper substrate. Due to the reflection effect between the copper substrate and the textured grooves, the laser's contact time with the substrate is prolonged after multiple reflections, retaining more energy within the textured grooves. This reduces laser dissipation during ultra-high-speed laser cladding, allowing the copper substrate to absorb more energy and further facilitating the melting of the sprayed powder.

[0060] The method of pre-fabricating a texture on the copper substrate in this invention also enhances the bonding force between the coating and the copper substrate, compensating for the problem of low bonding strength between the coating and the copper substrate caused by the excessively fast melting speed in ultra-high-speed laser cladding. The presence of texture increases the contact area between the copper substrate and the coating. The molten coating material in the texture fills these microstructures, and after solidification, it forms a metallurgical bond with the copper substrate.

[0061] During the cooling process of ultra-high-speed laser cladding, the large temperature gradient within the material leads to uneven shrinkage. The outer layer cools and shrinks faster than the inner layer, generating significant internal stress. When this internal stress exceeds the material's yield strength, cracking of the cladding coating occurs. This invention significantly reduces the internal stress of the coating by pre-fabricating a texture on the copper substrate, such as... Figure 3 As shown, the stress of the textured coating diffuses into the grooves, effectively dispersing the stress and reducing the occurrence of cracks. At the same time, rounding the corners of the texture can further avoid coating defects caused by stress concentration. In contrast, the stress of the untextured coating is too concentrated, which can easily cause cracks in the coating. Attached Figure Description

[0062] Figure 1 A schematic diagram of the equipment for hot air treatment of the porous agglomerated particles formed in this invention;

[0063] Figure 2 This is a reflection path diagram of the laser in the porous aggregated particles formed in this invention;

[0064] Figure 3 This is a schematic diagram of stress diffusion during coating preparation after prefabrication of texture on the substrate according to the present invention;

[0065] Figure 4 This is a diagram showing the reflection path of laser light in the copper substrate after the texture of this invention.

[0066] Figure 5 This is a schematic diagram showing the bonding between the copper alloy coating and the textured copper substrate of the present invention;

[0067] Figure 6 This is a schematic diagram of the hollow quadrangular frustum groove texture of the present invention;

[0068] Figure 7 This is a schematic diagram of the hollow cylindrical groove texture of the present invention;

[0069] Figure 8 This is a schematic diagram of the hollow triangular prism groove texture of the present invention;

[0070] Figure 9 This is a temperature analysis diagram of the cladding temperature field of the copper alloy coating in Embodiment 1 of the present invention;

[0071] Figure 10 This is a temperature analysis diagram of the cladding temperature field of the copper alloy coating in Comparative Example 2 of this invention.

[0072] Explanation of reference numerals in the attached figures:

[0073] 1-Mixed liquid, 2-Pressure water pump, 3-Atomized liquid spray outlet, 4-Hot air blower, 5-Sealed drying oven, 6-Filter screen, 7-Powder collector, 8-Coating, 9-Textured copper substrate, 10-Textured groove, 11-Incident laser, 12-Porosity of porous aggregated particles. Detailed Implementation

[0074] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0075] Example 1

[0076] (1) Because copper-based powder has a low melting point, it is easier to break down and agglomerate it compared to those powder materials with higher melting points. 150 grams of CuZrAlCo alloy powder with a particle size of 30µm was processed in a QYF-260 air jet mill and graded by air jet milling for 2 hours. The grinding gas pressure was 0.7MPa, and the powder was ground to a particle size of 3µm. The pulverized powder is thoroughly mixed with 300g of deionized water, 2g of polyethylene wax binder, and 1g of ethyl acetate dispersant to form a mixture 1. Mixture 1 is piped into a pressure water pump 2, with the pump pressure set to 30 MPa. The mixture is atomized through a nozzle and sprayed out through an atomized liquid outlet 3. Simultaneously, hot air is blown into a sealed drying chamber 5 by a hot air blower 4 for heat treatment. The hot air temperature is set to 200°C, causing the atomized droplets (approximately 100 µm) to rapidly evaporate the solvent in the hot air, forming porous agglomerated particles. Finally, the dried powder is recovered in a powder collector 7 through a funnel and filter screen 6. Specifically, a schematic diagram of the equipment for hot air treatment of the porous agglomerated particles formed in the present invention is shown below. Figure 1 As shown.

[0077] (2) First, grind the surface of the copper substrate using a grinding machine, and then clean the surface of the copper substrate using anhydrous ethanol. Place the prepared copper substrate (CuCrZr) on the worktable of the laser etching machine, set the distance between the laser head nozzle and the copper substrate to 15mm, the speed to 3mm / s, the frequency to 70Hz, the laser power to 1500W, the pulse to 12 microseconds, and the laser wavelength to 355nm; prepare the following on the copper substrate: Figure 6The hollow frustum-shaped groove texture shown has the following configuration: the smaller bottom surface of the frustum-shaped groove is located inside the copper substrate and is denoted as the lower bottom surface. The lower bottom surface is square and all corners are rounded. The larger bottom surface of the frustum-shaped groove is located on the surface of the copper substrate and is denoted as the upper bottom surface. The upper bottom surface is square and all corners are rounded. The initial width of the upper bottom surface before rounding is 50µm, and the rounded radius of the upper bottom surface after rounding is 10µm. The initial width of the lower bottom surface before rounding is 25µm, and the rounded radius of the lower bottom surface after rounding is 5µm. The depth of the hollow frustum-shaped groove is 50µm, and the spacing between the hollow frustum-shaped grooves is 50µm. Finally, the copper substrate surface is cleaned again with anhydrous ethanol to remove debris.

[0078] (3) An ultra-high-speed laser cladding system was used. The pre-textured copper substrate was placed on the worktable, and the prepared porous agglomerated particles were poured into the powder feeder. The distance between the laser head nozzle and the untextured part of the copper substrate surface was set to 15 mm. Coaxial powder feeding was used in a bow-shaped reciprocating motion. The scanning speed was 250 mm / s, and the powder feeding rate was set to 2 g / min. The angle between the laser head and the horizontal plane of the copper substrate was preset to 85°. Laser cladding was performed under a 700 nm wavelength laser with a power of 1900 W and a cladding length of 30 mm. The prepared coating surface was smooth and free of obvious defects and cracks.

[0079] This invention, through the preparation of porous agglomerated particles and the pre-fabrication of texture on the copper substrate, reduces laser dissipation during ultra-high-speed laser cladding, allowing for more efficient utilization of laser energy by the coating powder. This efficient energy absorption causes more powder particles to rapidly heat up under the laser, reaching and exceeding their melting point, thereby achieving complete melting of the coating powder and forming a metallurgical bond with the copper substrate. This excellent bonding method results in a dense internal structure of the coating prepared by this invention, free from obvious defects such as pores and cracks. Furthermore, the texture of this invention increases the contact area between the copper substrate and the coating, enhancing the bonding between them, reducing internal stress, eliminating morphological defects, and significantly improving the wear resistance and service life of the coating. Specifically:

[0080] In ultra-high-speed laser cladding, as porous agglomerated particles are injected into the textured copper substrate surface, the irregular pits and voids on the surface of the porous agglomerated particles cause them to scatter when irradiated by the laser. Figure 2 As shown, part of the incident laser 11 is reflected (i.e. Figure 2 (Illustrative diagram using a zigzag laser) Another portion of the incident laser 11 passes through the pores 12 of the porous agglomerate particles and enters the interior of the porous agglomerate particles (i.e., Figure 2(Illustration using a linear laser) Porous agglomerated particles can absorb more laser energy, thereby improving their melting efficiency and achieving complete melting of the coating powder, forming a metallurgical bond with the copper substrate. Furthermore, during the ultra-high-speed laser cladding process, such as... Figure 4 As shown, part of the incident laser 11 is injected into the textured groove 10 pre-prepared in the copper substrate. Due to the reflection effect of the copper substrate and the textured groove, the laser is reflected multiple times, which prolongs the time the laser acts on the copper substrate. More energy is retained in the textured groove, and the copper substrate can absorb more energy, which is beneficial to the melting of the powder injected into it.

[0081] The method of pre-fabricating the texture on the copper substrate in this invention also enhances the adhesion between the coating and the copper substrate, compensating for the problem of low adhesion strength between the coating and the copper substrate caused by the excessively fast cladding speed in ultra-high-speed laser cladding. For example... Figure 5 As shown, the upper region is the coating 8, and the lower region is the textured copper substrate 9. The presence of texture increases the contact area between the copper substrate and the coating. In the texture, the molten coating material fills these microstructures, and after solidification, it forms a mechanical interlock, similar to the "anchoring" effect.

[0082] During the cooling process of ultra-high-speed laser cladding, the large temperature gradient within the material leads to uneven shrinkage. The outer layer cools and shrinks faster than the inner layer, generating significant internal stress. When this internal stress exceeds the material's yield strength, cracks appear in the cladding coating. This invention significantly reduces the internal stress of the coating by pre-fabricating a texture on the copper substrate, such as... Figure 3 As shown, the upper region is coating 8, and the lower region is the textured copper substrate 9. The stress of the textured coating on the surface diffuses into the trench, which effectively disperses the stress and reduces the generation of cracks. At the same time, the rounded corners of the texture can further avoid coating defects caused by stress concentration. In contrast, the stress of the untextured coating is too concentrated, which can easily cause cracks in the coating.

[0083] Example 2

[0084] Step (1) is the same as step (1) in Example 1.

[0085] (2) First, grind the surface of the copper substrate (CuCrZr) using a grinding machine, and clean the surface of the copper substrate with anhydrous ethanol. Place the prepared copper substrate on the worktable of the laser etching machine, set the distance between the laser head nozzle and the copper substrate to 15mm, the speed to 4mm / s, the frequency to 80Hz, the laser power to 1700W, the pulse to 12 microseconds, and the laser wavelength to 355nm; prepare the following on the copper substrate: Figure 7The hollow cylindrical slots shown are characterized by having a diameter of 50µm on both the upper and lower bottom surfaces and a depth of 50µm. The spacing between the hollow cylindrical slots is 50µm. Finally, the copper substrate surface was cleaned again with anhydrous ethanol to remove debris.

[0086] (3) An ultra-high-speed laser cladding system was used. The pre-textured copper substrate was placed on the worktable, and the prepared porous agglomerated particles were poured into the powder feeder. The distance between the laser head nozzle and the untextured part of the copper substrate surface was set to 15 mm. Coaxial powder feeding was used in a bow-shaped reciprocating motion. The scanning speed was 250 mm / s, and the powder feeding rate was set to 2 g / min. The angle between the laser head and the horizontal plane of the copper substrate was preset to 85°. Laser cladding was performed under a 700 nm wavelength laser with a power of 1900 W and a cladding length of 30 mm. The prepared coating surface was smooth and free of obvious defects and cracks.

[0087] Example 3

[0088] Step (1) is the same as step (1) in Example 1.

[0089] (2) First, grind the surface of the copper substrate (CuCrZr) using a grinding machine, and clean the surface of the copper substrate with anhydrous ethanol. Place the prepared copper substrate on the worktable of the laser etching machine, set the distance between the laser head nozzle and the copper substrate to 15mm, the speed to 2mm / s, the frequency to 80Hz, the laser power to 1600W, the pulse to 12µs, and the laser wavelength to 355nm; prepare the following on the copper substrate: Figure 8 The hollow triangular prism-shaped groove shown has an upper and lower base surface that are correspondingly identical equilateral triangles, and the corners of the upper and lower base surfaces of the equilateral triangles are all rounded. The initial side length of the equilateral triangles before rounding is 50µm, and the radius of the rounded corners is 10µm. The depth of the hollow triangular prism-shaped groove is 50µm. The groove spacing between the hollow triangular prism-shaped grooves is 50µm. Finally, the copper substrate surface is cleaned again with anhydrous ethanol to remove debris.

[0090] (3) An ultra-high-speed laser cladding system was used. The pre-textured copper substrate was placed on the worktable, and the prepared porous agglomerated particles were poured into the powder feeder. The distance between the laser head nozzle and the untextured part of the copper substrate surface was set to 15 mm. Coaxial powder feeding was used in a bow-shaped reciprocating motion. The scanning speed was 250 mm / s, and the powder feeding rate was set to 2 g / min. The angle between the laser head and the horizontal plane of the copper substrate was preset to 85°. Laser cladding was performed under a 700 nm wavelength laser with a power of 1900 W and a cladding length of 30 mm. The prepared coating surface was smooth and free of obvious defects and cracks.

[0091] Example 4

[0092] (1) 150 g of CuSn with a particle size of 30 µm 12 Ni2 alloy powder was processed in a QYF-260 air classifier using air jet milling for 2 hours at a gas pressure of 0.8 MPa, resulting in powder with a particle size of 3 µm. The powder was then thoroughly mixed with 300 g of deionized water, 1 g of terpene resin binder, and 2 g of isopropanol dispersant. The mixture was then piped into a pressure pump at a pressure of 30 MPa. The mixture was atomized through a nozzle and then heat-treated with a hot air blower at a temperature of 200°C. This allowed the atomized droplets to rapidly evaporate the solvent in the hot air, forming porous agglomerated particles. Finally, the dried powder was collected through a funnel.

[0093] Steps (2) and (3) are the same as steps (2) and (3) in Example 1.

[0094] Example 5

[0095] Step (1) is the same as step (1) in Example 4.

[0096] (2) First, grind the surface of the copper substrate (CuCrZr) using a grinding machine, and clean the surface of the copper substrate with anhydrous ethanol. Place the prepared copper substrate on the worktable of the laser etching machine, set the distance between the laser head nozzle and the copper substrate to 15mm, the speed to 4mm / s, the frequency to 80Hz, the laser power to 1700W, the pulse to 12µs, and the laser wavelength to 356nm, and prepare the following on the copper substrate: Figure 7 The hollow cylindrical slots shown are characterized by having a diameter of 50µm on both the upper and lower bottom surfaces and a depth of 50µm. The spacing between the hollow cylindrical slots is 50µm. Finally, the copper substrate surface was cleaned again with anhydrous ethanol to remove debris.

[0097] (3) An ultra-high-speed laser cladding system was used. The pre-textured copper substrate was placed on the worktable, and the prepared porous agglomerated particles were poured into the powder feeder. The distance between the laser head nozzle and the untextured part of the copper substrate surface was set to 15 mm. Coaxial powder feeding was used in a bow-shaped reciprocating motion with a scanning speed of 260 mm / s and a powder feeding rate of 2 g / min. The angle between the laser head and the horizontal plane of the copper substrate was preset to 85°. Laser cladding was performed under a 700 nm wavelength laser with a power of 2000 W and a cladding length of 30 mm. The prepared coating surface was smooth and free of obvious defects and cracks.

[0098] Example 6

[0099] Step (1) is the same as step (1) in Example 4.

[0100] (2) First, grind the surface of the copper substrate using a grinding machine, and then clean the surface of the copper substrate using anhydrous ethanol. Place the prepared copper substrate on the worktable of the laser etching machine, set the distance between the laser head nozzle and the copper substrate (CuCrZr) to 15mm, the speed to 2mm / s, the frequency to 80Hz, the laser power to 1600W, the pulse to 12µs, and the laser wavelength to 356nm, and prepare the following on the copper substrate: Figure 8 The hollow triangular prism-shaped groove shown has an upper and lower base surface that are correspondingly identical equilateral triangles, and the corners of the upper and lower base surfaces of the equilateral triangles are all rounded. The initial side length of the equilateral triangles before rounding is 50µm, and the radius of the rounded corners is 10µm. The depth of the hollow triangular prism-shaped groove is 50µm. The groove spacing between the hollow triangular prism-shaped grooves is 50µm. Finally, the copper substrate surface is cleaned again with anhydrous ethanol to remove debris.

[0101] (3) An ultra-high-speed laser cladding system was used. The pre-textured copper substrate was placed on the worktable, and the prepared porous agglomerated particles were poured into the powder feeder. The distance between the laser head nozzle and the untextured part of the copper substrate surface was set to 15 mm. Coaxial powder feeding was used in a bow-shaped reciprocating motion. The scanning speed was 250 mm / s, and the powder feeding rate was set to 2 g / min. The angle between the laser head and the horizontal plane of the copper substrate was preset to 85°. Laser cladding was performed under a 700 nm wavelength laser with a power of 1900 W and a cladding length of 30 mm. The prepared coating surface was smooth and free of obvious defects and cracks.

[0102] Comparative Example 1

[0103] It adopts the same preparation method as Example 1, except that, according to the conditions in Example 1, CuZrAlCo alloy powder is pulverized by airflow to copper-based powder with a particle size of 3µm, and then it is used directly as coating powder instead of being prepared into porous agglomerated particles.

[0104] Comparative Example 2

[0105] It adopts the same preparation method as Example 1, except that step (2) is not performed, that is, the copper substrate is not laser etched and the texture is not prepared on the copper substrate.

[0106] Test example:

[0107] Temperature analysis of the cladding temperature field was performed using Abqaus software on the textured coating (the coating of Example 1) and the non-textured coating (the coating of Comparative Example 2). The results are as follows: Figure 9 and Figure 10As shown in the figure, through temperature field simulation, it can be seen that the temperature of the coating in Example 1 is significantly lower than that of the untextured coating in Comparative Example 2. This is because the grooves of the texture in Example 1 delay heat transfer, making the temperature distribution more uniform, thereby reducing thermal stress.

[0108] The coating samples prepared in the examples and comparative examples were placed in a tooling fixture, and the fixture was placed on a tensile and compressive testing bench to test their bonding strength. The specific results are shown in Table 1:

[0109] Bond strength formula:

[0110] In the formula: For bonding strength, F is the maximum shear stress, and S represents the bonding area between the coating and the copper substrate.

[0111] Table 1

[0112] As can be seen from the results in Table 1, the coating prepared based on the texture structure of the present invention can significantly improve the bonding strength of the coating compared with traditional coatings (such as the coating of Comparative Example 2) by increasing the interfacial contact area and forming a mechanical interlocking structure.

[0113] The residual stress of the coating was detected by X-ray stress analyzer. By measuring the diffraction angle change of a specific crystal plane in the crystalline material, the elastic deformation of the interplanar spacing was calculated, and the magnitude of the residual stress was derived. The results are shown in Table 2.

[0114] Using a UV-Vis-IR absorption spectrometer, light sources of different wavelengths were emitted and directly incident on the prepared textured copper substrate and the porous aggregated particles loaded on the surface of the textured copper substrate. The reflected light was measured to obtain the common reflectivity of the prepared textured copper substrate and the porous aggregated particles (referred to as the maximum reflectivity in Table 2). The specific results are shown in Table 2.

[0115] Table 2

[0116]

[0117] As can be seen from the results in Table 2, by comparing Examples 1-6 with Comparative Example 2, it can be seen that the textured coating prepared in the embodiments of the present invention has a better residual stress performance than the coating without texture. The pre-fabricated texture of the present invention greatly reduces the residual stress of the coating and effectively reduces the probability of crack defects caused by stress.

[0118] By comparing Examples 1-6 with Comparative Example 2, it can be seen that the presence of texture increases the contact area between the copper substrate and the coating. The molten coating material fills these microstructures in the texture, and after solidification, it forms a mechanical interlock, similar to an "anchoring" effect, thereby greatly increasing the bonding strength between the coating and the copper substrate.

[0119] When the incident laser enters the textured grooves, due to the reflection effect of the textured grooves within the copper substrate, the laser undergoes multiple reflections, increasing the time the laser spends on the copper substrate. More energy is retained within the grooves, allowing the copper substrate to absorb more energy. Test results show that the coating with the pre-textured structure of this invention has a significantly lower laser reflectivity compared to the coating without pre-textured structure in Comparative Example 2.

[0120] By comparing Examples 1-6 with Comparative Example 1, it can be seen that the porous agglomerates prepared in the embodiments of the present invention have irregular pits and pores on their surface. After laser irradiation, part of the laser is reflected away, and the other part of the laser passes through the pores of the porous agglomerates and enters the interior of the porous agglomerates, so that the porous agglomerates absorb more energy, thereby improving the melting efficiency of the powder, thereby achieving full melting of the coating powder, and thus better contacting the copper substrate surface and undergoing metallurgical bonding.

[0121] Therefore, this invention, through the preparation of porous agglomerated particles and the pre-fabrication of texture on the copper substrate, reduces laser dissipation during ultra-high-speed laser cladding, allowing the laser energy to be utilized more efficiently by the coating powder. This efficient energy absorption causes more powder particles to rapidly heat up under the laser, reaching and exceeding their melting point, thereby achieving full melting of the coating powder and better contact with the copper substrate surface for metallurgical bonding. This excellent bonding method results in a dense internal structure of the coating prepared by this invention, free from obvious pores, cracks, and other defects, providing a solid microstructural foundation for the coating.

[0122] Furthermore, improving the residual stress state of the coating is also a key factor in enhancing coating performance. During laser cladding, rapid heating and cooling generate significant residual stress within the coating. By pre-texturing the copper substrate, the residual stress is effectively reduced. A lower residual stress level results in a more uniform stress distribution within the coating, preventing stress concentration and thus reducing the likelihood of cracking due to stress concentration. This significantly improves the coating's wear resistance and service life. Therefore, regarding wear resistance, as demonstrated in Examples 1-6 and Comparative Examples 1 and 2, the coatings with pre-textured copper substrates and porous agglomerated powder treatment exhibit a significantly lower wear rate compared to coatings without such treatment, thus significantly improving the coating's wear resistance.

[0123] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a low-reflection, strong-bonding, low-stress copper alloy coating, characterized in that, The process includes the following steps: (1) mixing copper-based powder, solvent, binder and dispersant evenly to obtain a mixture, atomizing the mixture and spraying it out through the atomizing nozzle, and then treating the sprayed atomized droplets with hot air to obtain porous agglomerated particles; (2) using laser etching to create a texture on the copper substrate, cleaning it, and obtaining a textured copper substrate; (3) loading the porous agglomerated particles onto the textured copper substrate surface by ultra-high speed laser cladding to obtain a low-reflection, strong-bonding, low-stress copper alloy coating.

2. The method for preparing a low-reflection, strong-bonding, low-stress copper alloy coating according to claim 1, characterized in that: Step (1), The copper-based powder has a particle size of 1~5µm; and / or, The copper-based powder is selected from CuZrAlCo alloy powder and CuSn. 12 Ni2 alloy powder, CuCrZr alloy powder, CuZrNiAl alloy powder or CuAl 10 At least one of the alloy powders; and / or, The solvent is water; and / or, The adhesive is at least one of polyethylene wax or terpene resin; and / or, The dispersant is at least one of ethyl acetate or isopropanol.

3. The method for preparing a low-reflection, strong-bonding, low-stress copper alloy coating according to claim 1, characterized in that: Step (1), The amount of copper-based powder added is 100-200 grams; and / or, The amount of solvent added is 200-400 grams; and / or, The amount of adhesive added is 1-2 grams; and / or, The amount of the dispersant added is 1-2 grams; and / or, The size of the atomized droplets is 10~200µm; and / or, The hot air temperature for hot air treatment is 150~300°C.

4. The method for preparing a low-reflection, strong-bonding, low-stress copper alloy coating according to claim 1, characterized in that: Step (2), The texture is a hollow truncated quadrangular groove, wherein the smaller bottom surface of the hollow truncated quadrangular groove is located inside the copper substrate and is referred to as the bottom surface. The bottom surface is square and all corners of the bottom surface are rounded. The initial width of the bottom surface before rounding is 25~50µm, and the radius of the rounded corners after rounding is 5~10µm. The larger bottom surface in the hollow truncated quadrangular groove is located on the surface of the copper substrate and is referred to as the upper bottom surface. The upper bottom surface is square and all corners of the upper bottom surface are rounded. The initial width of the upper bottom surface before rounding is 50~80µm, and the radius of the rounded corners after rounding is 10~20µm. The depth of the hollow truncated quadrangular groove is 50~80µm; the spacing between the hollow truncated quadrangular grooves is 50~80µm.

5. The method for preparing a low-reflection, strong-bonding, low-stress copper alloy coating according to claim 1, characterized in that: Step (2), The texture is a hollow triangular prism-shaped groove, wherein the upper and lower bases of the hollow triangular prism-shaped groove are corresponding identical equilateral triangles, and the corners of the upper and lower bases of the equilateral triangles are rounded; the initial side length of the equilateral triangles before rounding is 50~80µm, and the rounded corner radius is 10~15µm; the depth of the hollow triangular prism-shaped groove is 50~80µm; the groove spacing between the hollow triangular prism-shaped grooves is 50~80µm; and / or, The texture is in the shape of hollow cylindrical holes and grooves; the diameter of the upper and lower bottom surfaces of the hollow cylindrical holes and grooves is 50~80µm; the depth of the hollow cylindrical holes and grooves is 50~80µm; and the spacing between the hollow cylindrical holes and grooves is 50~80µm.

6. The method for preparing a low-reflection, strong-bonding, low-stress copper alloy coating according to claim 1, characterized in that: Step (2), In the laser etching process The distance between the laser head nozzle and the copper substrate is 13~20mm; and / or, The laser head speed is 2~5mm / s; and / or, The laser head has a frequency of 60~80Hz; and / or, Laser power of 1000~2000W, pulse duration of 10~15 microseconds; and / or, The laser wavelength is 354~356nm.

7. The method for preparing a low-reflection, strong-bonding, low-stress copper alloy coating according to claim 1, characterized in that: Step (3), The ultra-high-speed laser cladding uses a laser wavelength of 600-750 nm and a power of 1500-3000 W; and / or, The ultra-high-speed laser cladding uses a coaxial powder feeding method, where the powder consists of porous agglomerated particles; the powder feeding rate is set to 1~2 g / min; and / or, The distance between the nozzle of the ultra-high-speed laser cladding and the surface of the untextured copper substrate in the textured copper substrate is 10-15 mm; and / or, The laser focus of the ultra-high-speed laser cladding adopts a bow-shaped reciprocating pattern; and / or, The laser scanning speed of the ultra-high-speed laser cladding is 200mm~350mm / s; and / or, The angle between the laser head of the ultra-high-speed laser cladding and the horizontal plane of the copper substrate is 60°~85°.

8. A low-reflection, strong-bond, low-stress copper alloy coating prepared by the method of any one of claims 1-7.

9. The low-reflection, strong-bonding, low-stress copper alloy coating according to claim 8, characterized in that, The bonding strength of the low-reflection, high-bond, low-stress copper alloy coating is 300~400MPa. The residual stress of the low-reflection, strong-bonded, low-stress copper alloy coating is 50~150MPa. The volumetric wear rate of the low-reflectivity, high-bondage, low-stress copper alloy coating is 1.8 × 10⁻⁶. -5 ~ 2.2×10 -5 mm 3 ·N -1 ·m -1 .

10. The application of a low-reflection, strong-bond, low-stress copper alloy coating prepared by the method of any one of claims 1-7 in heat dissipation coatings for electronic components, surface treatment of precision aerospace parts, anti-wear coatings for high-end molds, and conductive and wear-resistant components.

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