A CuZn coating cladding method for copper-zinc alloy surface based on red-blue laser synergistic enhancement, and its application.

Abstract

This invention discloses a CuZn coating cladding method for copper-zinc alloy surfaces based on red-blue laser synergistic enhancement, its preparation method, and its application, belonging to the field of laser surface engineering technology. This invention employs coaxial composite cladding with infrared and blue lasers to prepare a CuZn coating on the surface of a copper-zinc alloy substrate. By controlling the infrared laser power to 100-300 W and the blue laser power to 500-1000 W, and limiting the infrared laser spot diameter to be smaller than the blue laser spot diameter, the scanning speed is set to 300-700 mm / s, and cladding is performed in a protective atmosphere with an oxygen content below 200 ppm. This invention utilizes the synergistic effect of the high energy density of the infrared laser and the short-wavelength absorption enhancement effect of the blue laser on high-reflectivity alloy surfaces to solve the problems of difficult molten pool formation, poor metallurgical bonding, and interpass cracking caused by the high reflectivity, high thermal conductivity, and Zn volatilization of copper-zinc alloys.

Description

Technical Field

[0001] This invention relates to a CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement, its preparation method, and its application. Specifically, it relates to a method for cladding a copper-zinc coating on a copper-zinc alloy surface based on red-blue laser synergistic enhancement, and the cladding layer with special microstructure and excellent mechanical properties prepared by this method. It belongs to the field of laser surface engineering technology. Background Technology

[0002] Currently, brass (Cu-Zn alloy) is commonly used as the core material in copper alloy guide rails, utilizing its excellent electrical and thermal conductivity. However, in actual service, the guide rail surface must withstand the coupling effects of high-speed sliding friction, high temperature, and high pressure, leading to severe surface wear and directly affecting the lifespan and firing accuracy of the copper alloy guide rail. Therefore, improving the wear resistance of the brass surface while ensuring the high electrical and thermal conductivity of the substrate has significant engineering value.

[0003] Surface coating technology is an effective means to improve the surface properties of materials. Currently, the commonly used wear-resistant coating preparation technologies for copper alloy components mainly include electroplating, thermal spraying, and casting infiltration. Although electroplating technology is low in cost, it poses serious environmental pollution problems; the coating prepared by thermal spraying technology is mechanically bonded to the substrate, resulting in low bonding strength and easy peeling under stress conditions; the casting infiltration process is prone to producing porosity defects, limiting its application range.

[0004] Laser cladding technology has become an important technology for surface modification due to its advantages such as high flexibility, small heat-affected zone, high metallurgical bonding strength between coating and substrate, and dense structure. However, laser cladding of copper alloy surfaces faces unique challenges: on the one hand, copper alloys have extremely low absorption rates for infrared lasers with a wavelength of 1064 nm (usually less than 5%), and copper alloys have extremely high thermal conductivity, making it difficult for the molten pool to achieve a stable power density, which easily leads to problems such as poor forming and stress cracking; on the other hand, if a blue laser with a wavelength of 450 nm is used to improve the absorption rate by utilizing the short-wave absorption enhancement effect, the energy density is still insufficient when cladding copper alloys on copper alloy surfaces due to the current power limitations of single-tube semiconductor chips, even though high-power blue lasers have achieved kilowatt-level output. This limits the cladding efficiency, and the uneven energy distribution of the flat-top beam at the edge of the molten pool easily causes warping and incomplete fusion.

[0005] In recent years, infrared-blue laser coaxial composite cladding technology has attracted attention. This technology aims to combine the high energy density of infrared lasers with the high absorption rate of blue lasers for high-reflectivity alloys. However, existing research mainly focuses on cladding copper alloys onto aluminum alloy surfaces or nickel-based alloys onto copper alloy surfaces, and the process parameter window has not yet been optimized. In particular, when cladding copper-zinc coatings of the same or similar composition onto copper-zinc alloy surfaces, the low boiling point and high volatility of Zn cause strong scattering, diffuse reflection, and refraction effects on the laser, further reducing the laser energy utilization rate and leading to problems such as unstable solidification of the molten pool, cracking in the inter-pass overlap zone, and uneven coating microstructure. Currently, no research has reported the ability to obtain a defect-free, high-hardness CuZn coating with excellent electrical and thermal conductivity on high-zinc brass surfaces such as H59 through red-blue laser composite cladding.

[0006] Therefore, there is an urgent need to develop a red-blue laser composite cladding method for copper-zinc alloy substrates. Through precise process coordination control, this method can solve the cladding problems caused by high reflectivity, high thermal conductivity, and element volatilization, and obtain a copper-zinc cladding layer with uniform structure and excellent performance. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing laser cladding techniques for copper-zinc alloy surfaces, such as difficulties in molten pool formation, poor metallurgical bonding, interpass cracking, uneven microstructure, and limited coating functionality. This invention provides a method for preparing CuZn cladding coatings on copper-zinc alloy surfaces based on synergistic red-blue laser energy enhancement. By employing a specific power ratio, spot size matching, and synergistic control of scanning speed between low-power infrared lasers and high-power blue lasers, this invention achieves spatial gradient distribution and dynamic balance of molten pool energy, thereby obtaining a CuZn cladding layer free of metallurgical defects, possessing a unique wavy texture, and exhibiting significantly improved nano-hardness.

[0008] Meanwhile, the present invention provides a CuZn coating cladding on the surface of a copper-zinc alloy based on red-blue laser synergistic enhancement.

[0009] Meanwhile, this invention provides an application of CuZn coating cladding on the surface of copper-zinc alloy based on red-blue laser synergistic enhancement.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for laser cladding of a copper-zinc alloy surface with a copper-zinc coating (i.e., a method for preparing a CuZn coating on a copper-zinc alloy surface based on red-blue laser synergistic enhancement) employs coaxial composite cladding of infrared and blue lasers to prepare a CuZn coating on the surface of a copper-zinc alloy substrate; wherein: The infrared laser has a power of 100-300 W, a wavelength of 1000-1100 nm, a spot diameter of 0.3-0.6 mm, and exhibits a Gaussian energy distribution. The blue laser has a power of 500-1000 W, a wavelength of 430-470 nm, a spot diameter of 1.5-2.5 mm, and a flat-top energy distribution. The infrared laser spot diameter is smaller than the blue laser spot diameter, and the focal points of both are aligned with the powder convergence point; The scanning speed is 300-700 mm / s; The powder delivery gas flow rate is 10-20 L / min; The cladding process is carried out in an inert protective atmosphere (such as Ar gas), with the oxygen content strictly controlled below 200 ppm.

[0011] Preferably, the power of the infrared laser is 200-300 W, and the power of the blue laser is 600-800 W.

[0012] Preferably, the infrared laser spot diameter is 0.4 mm, and the blue laser spot diameter is 1.75 mm.

[0013] Preferably, the scanning speed is 500 mm / s.

[0014] Preferably, the copper-zinc alloy matrix is ​​H59 high-zinc brass, and the cladding powder is CuZn40 powder with a particle size distribution of D10 = 40-55 μm, D50 = 70-80 μm, D90 = 100-110 μm, and a loose packing density of 4.2-4.6 g / cm³. 3 The tap density is 5.0-5.3 g / cm³. 3 .

[0015] Preferably, when performing multi-pass cladding, the overlap rate between adjacent passes is 0.7-0.9 mm.

[0016] Preferably, when performing multi-layer, multi-pass cladding, the thickness (layer height) of a single cladding layer is 0.8-1.2 mm.

[0017] The present invention also provides a copper-zinc alloy surface cladding layer prepared by the above method, wherein the cladding layer forms a dense metallurgical bond with the copper-zinc alloy substrate without cracks or pores; the cladding layer has a wavy texture structure parallel to the substrate direction, wherein the wavy edges of the wavy texture are fine equiaxed crystals with an average grain size of 1-2 μm; the interior of the wavy texture is columnar dendrites that grow oriented in the opposite direction of heat flow; the nanohardness of the cladding layer is 140.2-193.4 Hv, which is much higher than the hardness of the substrate (about 118 Hv).

[0018] Specifically, a CuZn coating is clad on the surface of a copper-zinc alloy based on red-blue laser synergistic enhancement. The CuZn coating forms a metallurgical bond with the copper-zinc alloy substrate, and the coating has a wave texture distributed along the direction parallel to the substrate. The wave texture contains equiaxed crystals, and the wave texture contains columnar crystals.

[0019] The size of equiaxed crystals is smaller than that of columnar crystals, and the size of both equiaxed crystals and columnar crystals is much smaller than the grain size of the copper-zinc alloy matrix.

[0020] The nanoindentation hardness of the fine-grained and coarse-grained regions is significantly higher than that of the matrix.

[0021] The cladding channels form a dense metallurgical bond with the substrate and between channels, without obvious metallurgical defects such as cracks and pores.

[0022] The cladding layer has no warping or incomplete fusion defects in the multiple overlapping areas and interlayer bonding areas.

[0023] An application of a red-blue laser composite cladding device in the preparation of a wear-resistant conductive coating on the surface of a copper-zinc alloy, the device being equipped with an infrared laser with a power of 100-300 W and a blue laser with a power of 500-1000 W, for cladding CuZn40 powder on the surface of an H59 brass substrate to form the cladding layer of the present invention.

[0024] Application of CuZn coating cladding on high-zinc brass surfaces based on red-blue laser synergistic enhancement.

[0025] Application of CuZn coating cladding on copper-zinc alloy surface based on red-blue laser synergistic enhancement in copper alloy guide rails.

[0026] A high-zinc brass, the surface of which is coated with a CuZn coating based on red-blue laser synergistic enhancement of copper-zinc alloy surface according to the present invention.

[0027] A copper alloy guide rail includes a CuZn coating clad on the surface of a copper-zinc alloy based on red-blue laser synergistic enhancement, according to the present invention.

[0028] Compared with the prior art, the present invention has the following significant advantages: (1) Synergistic Energy Enhancement Mechanism Breaks Through High Reflectivity Bottleneck: This invention innovatively adopts a composite mode of "low-power Gaussian infrared laser + high-power flat-top blue laser". The infrared laser has a small spot size and high energy density, acting on the central region of the molten pool, providing sufficient energy to penetrate the highly reflective surface and form a deep-melting micropore effect, ensuring full metallurgical bonding between the powder and the matrix; the blue laser has a large spot size and a flat-top distribution, covering the edge of the molten pool and the heat-affected zone, utilizing the short-wave absorption enhancement effect to improve the overall absorption rate of the copper-zinc alloy to the laser. The synergistic effect of the two overcomes the insufficient energy caused by the high reflectivity of the single infrared laser, and also makes up for the edge warping and incomplete fusion defects of the molten pool caused by the insufficient energy density of the single blue laser.

[0029] (2) Active control of Zn volatilization: By limiting the infrared laser power to no more than 300 W, the violent boiling of the molten pool and the large-scale volatilization of Zn caused by excessively high energy density were avoided. At the same time, the flat-top distribution of the blue laser provided a relatively mild and uniform preheating and heat preservation effect, reducing the temperature gradient of the molten pool and suppressing the violent generation of Zn vapor. Combined with a low oxygen environment of less than 200 ppm, oxidation loss was further reduced, ensuring the stability of the coating composition.

[0030] (3) Unique wave texture structure and excellent mechanical properties: Under the optimized coupling effect of energy and temperature fields, wave textures parallel to the substrate direction are formed inside the molten pool. This texture is not a simple solidification defect, but a self-organized phenomenon formed by the interaction of energy fluctuations and solidification front. The texture consists of fine equiaxed crystals (average grain size of 1-2 μm) on the surface and directional columnar dendrites within the texture. This dual-mode structure combines the advantages of fine grain strengthening and directional solidification strengthening, resulting in a nanohardness of 160-193.4 Hv in the fine grain region and 140.2-150.4 Hv in the coarse grain region, which is about 30%-70% higher than that of the H59 matrix, significantly improving the wear resistance of the coating.

[0031] (4) Multi-pass, multi-layer defect-free forming: By precisely controlling the overlap rate (0.7-0.9 mm), the Gaussian energy field of the infrared laser provides sufficient remelting depth in the overlap area, and the flat-top distribution of the blue laser ensures that the edges are fully melted, completely eliminating inter-pass warping and inter-layer non-fusion, and realizing the preparation of a large-area, crack-free, and pore-free dense coating.

[0032] (5) Maintaining the functional properties of the substrate: Since the cladding layer is a CuZn alloy with a composition similar to that of the substrate, and the heat-affected zone of laser cladding is small, the high electrical and thermal conductivity of the substrate is retained, which solves the problem that traditional nickel-based cladding layers are wear-resistant but have extremely poor electrical and thermal conductivity.

[0033] This invention discloses a method and cladding layer for cladding CuZn coatings on copper-zinc alloy surfaces based on synergistic red-blue laser enhancement. The method employs coaxial composite cladding with infrared and blue lasers to prepare a CuZn coating on the surface of a copper-zinc alloy substrate. By controlling the infrared laser power to 100-300 W and the blue laser power to 500-1000 W, and limiting the infrared laser spot diameter to be smaller than the blue laser spot diameter, the scanning speed is set to 300-700 mm / s, and cladding is performed in a protective atmosphere with an oxygen content below 200 ppm. This invention utilizes the synergistic effect of the high energy density of infrared lasers and the short-wavelength absorption enhancement effect of blue lasers on high-reflectivity alloy surfaces to solve the problems of difficult molten pool formation, poor metallurgical bonding, and interpass cracking caused by the high reflectivity, high thermal conductivity, and Zn volatilization of copper-zinc alloys. The resulting cladding layer forms a unique wave-like texture structure, with equiaxed crystals and columnar crystals alternating on the texture. The nano-indentation hardness of the fine-grained and coarse-grained regions is significantly higher than that of the substrate. Furthermore, a dense metallurgical bond is formed between the coating and the substrate, as well as between the layers, without obvious metallurgical defects such as cracks or pores. Attached Figure Description

[0034] Figure 1 Comparison of macroscopic surface morphology of CuZn40 coating fused onto H59 brass surface using different laser sources; Figure 2 Comparison of cross-sectional morphology of coatings clad with different laser sources; Figure 3 Comparison of microstructures of cladding coatings from different laser sources; Figure 4 This is a diagram showing the nanohardness distribution under the red-blue laser composite cladding process. Figure 5 The microstructure of a multi-channel sample clad with red-blue laser composite cladding. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0036] Example 1: Red-Blue Composite Cladding Process CuZn40 powder, prepared by plasma rotating electrode method, was used as the cladding material. The powder particle size was D10=47.75μm, D50=75.50μm, D90=104.00μm, with a loose density of 4.38 g / cm3 and a tap density of 5.13 g / cm3. The substrate was an H59 brass plate conforming to GB / T5231-2012 standard.

[0037] Before cladding, the substrate surface is sanded to remove the oxide layer and cleaned with anhydrous ethanol. The substrate is placed in the molding cavity, evacuated, and then filled with high-purity Ar gas to reduce the oxygen content in the cavity to below 200 ppm.

[0038] The experiment was conducted using a red-blue laser composite cladding device. This device was equipped with a 3000 W infrared laser (wavelength 1064 nm, spot diameter 0.4 mm, Gaussian distribution) and a 2000 W blue laser (wavelength 450 nm, spot diameter 1.75 mm, flat-top distribution). The optical path was adjusted to make the infrared and blue lasers coaxial, and their focal points aligned with the powder convergence point of the powder feeding nozzle. Ar gas was used for powder feeding at a flow rate of 15 L / min, and the powder tray rotation speed was 1.0 rpm.

[0039] The infrared laser power was set to 200 W, the blue laser power to 700 W, and the scanning speed to 500 mm / s, and a single-pass cladding was performed on the surface of the H59 substrate.

[0040] After cladding, metallographic samples were cut using wire cutting, cold-mounted with epoxy resin, and then wet-polished sequentially using 240# to 2000# wet sandpaper, rotating 90° at each pass and cooling with running water. Subsequently, rough polishing was performed using 2.5 μm diamond spray with a silk polishing cloth, followed by fine polishing with a 0.05 μm silica gel / alumina suspension using a short-pile polishing cloth. After cleaning with deionized water and anhydrous ethanol, the polished surfaces were immersed in an etchant prepared from 5 g ferric chloride, 10 mL concentrated hydrochloric acid, and 100 mL anhydrous ethanol at room temperature for 8-15 seconds. Once the grain boundaries were visible, the surfaces were immediately removed, rinsed, and dried.

[0041] Observed under an Olympus BX53 optical microscope and a ZEISS Sigma 300 field emission scanning electron microscope equipped with an EBSD probe.

[0042] like Figure 1 (c) Figure 2 (c) Figure 3 (b) Figure 5 The results showed that the red-blue composite cladding channel was continuous, smooth, and had a dark metallic color, with no obvious spatter, particle adhesion, or unevenness defects. The cross-section revealed a clear and smooth metallurgical interface between the molten pool and the substrate, free from warping, incomplete fusion, and cracks. The internal microstructure of the molten pool exhibited a typical wavy texture, distributed parallel to the substrate direction. The texture consisted of fine equiaxed crystals with an average grain size of approximately 1.2 μm; within the texture were columnar dendrites growing towards the center of the molten pool in the opposite direction of the heat flow.

[0043] like Figure 4As shown, the nanoindentation equipment was used to test different regions inside the molten pool. The nanohardness of the fine-grained region was 193.4 Hv, and the nanohardness of the coarse-grained region was 150.4 Hv, both of which were significantly higher than the 118.6 Hv of the H59 matrix.

[0044] This embodiment describes the application of a CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement on a high-zinc brass surface, wherein the high-zinc brass is H59 brass.

[0045] This embodiment describes the application of a CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement in a copper alloy guide rail.

[0046] A copper alloy guide rail includes a CuZn coating clad on the surface of a copper-zinc alloy based on red-blue laser synergistic enhancement, as described in this embodiment.

[0047] Comparative Example 1: Single Infrared Laser Cladding Infrared lasers were used only, with powers of 300 W, 700 W, 1000 W, and 1500 W, and a scanning speed of 500 mm / s. Figure 1 (a), Figure 2 (a) The results show that at 300 W, there is a clear boundary between the coating and the substrate, and no metallurgical bond is formed; at 700 W and above, the substrate forms a pinhole pattern, the recoil force blows away the powder, the cladding layer is almost non-existent, and keyhole defects appear at the end. The surface is uneven, with particle adhesion and depressions.

[0048] Comparative Example 2: Single Blue Laser Cladding Using only blue laser, with a power of 700 W, the scanning speeds were 200, 300, 700, and 1000 mm / s respectively. Figure 1 (b) Figure 2 (b) Figure 3 (a) Results show that all melt channels are black with unburnt soot powder. Cross-sections show that although there is a metallurgical bond between the bottom and the matrix, there is obvious warping on both sides, and the warping is more severe at lower scan speeds. Unmelted metal droplets adhere to the surface of the molten pool, and the interface between the molten pool and the matrix is ​​undulating. EBSD shows that the grain size within the molten pool is extremely uneven, with coarse grains (3.4-4.2 μm) in the warped edge areas, and there are also obvious size differences within the molten pool, indicating an unstable solidification state.

[0049] Example 2: Multi-pass cladding The optimized process parameters from Example 1 (200 W infrared laser + 700 W blue laser, scanning speed 500 mm / s) were used for multi-pass cladding. The overlap rate was set to 0.79 mm.

[0050] The results showed that a tight metallurgical bond was formed between the passes and between the pass and the substrate, without defects such as cracks or pores. The right end of the previous melt pool and the left end of the next melt pool achieved good remelting overlap, eliminating the warping characteristics of the single-pass edge. The microstructure of the overlap area was consistent with that of the pass center, both exhibiting wavy texture and alternating distribution of equiaxed and columnar crystals.

[0051] This embodiment describes the application of a CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement on a high-zinc brass surface, wherein the high-zinc brass is H59 brass.

[0052] This embodiment describes the application of a CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement in a copper alloy guide rail.

[0053] A copper alloy guide rail includes a CuZn coating clad on the surface of a copper-zinc alloy based on red-blue laser synergistic enhancement, as described in this embodiment.

[0054] Example 3: Multi-layer, multi-pass cladding Based on Example 2, multi-layer, multi-pass cladding was performed, with a single layer thickness (layer height) set to 1.0 mm. During the layer-by-layer cladding process, the oxygen content was kept below 200 ppm, and the scanning direction was alternately changed to reduce residual stress.

[0055] The results showed that the total thickness of the prepared coating reached several millimeters, the coating bonded well with the substrate, and there were no defects such as cracks or pores inside the coating. The multilayer overlap area had a dense structure, the interlayer interface disappeared, and the overall structure showed a uniform wavy texture.

[0056] This embodiment describes the application of a CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement on a high-zinc brass surface, wherein the high-zinc brass is H59 brass.

[0057] This embodiment describes the application of a CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement in a copper alloy guide rail.

[0058] A copper alloy guide rail includes a CuZn coating clad on the surface of a copper-zinc alloy based on red-blue laser synergistic enhancement, as described in this embodiment.

[0059] Example 4: Process Parameter Boundary Verification The only difference between this embodiment and Embodiment 1 is that: The infrared laser power was adjusted to 100 W, wavelength to 1000 nm, and spot diameter to 0.3 mm. The blue laser power was adjusted to 500 W, wavelength to 430 nm, and spot diameter to 1.5 mm. The scanning speed was adjusted to 300 mm / s, and the powder feeding gas flow rate was adjusted to 10 L / min.

[0060] The particle size distribution of CuZn40 powder is D10=40μm, D50=70μm, D90=100μm, and the loose bulk density is 4.2g / cm³. 3 The tap density is 5.0 g / cm³. 3 .

[0061] When performing multi-pass cladding, the overlap rate between adjacent passes is 0.7 mm.

[0062] When performing multi-layer, multi-pass cladding, the thickness (layer height) of a single cladding layer is 0.8 mm.

[0063] The results showed that the molten pool boundary was clear and the metallurgical bonding was good.

[0064] In this embodiment, a copper-zinc alloy surface cladding layer prepared by the above method forms a dense metallurgical bond with the copper-zinc alloy substrate without cracks or pores. The cladding layer has a wavy texture structure parallel to the substrate direction. The peak regions of the wavy texture are fine equiaxed crystals (i.e., fine-grained regions) with an average grain size of about 1 μm. The trough regions of the wavy texture are columnar dendrites (i.e., coarse-grained regions) that grow directionally in the opposite direction of heat flow. The nanohardness of the fine-grained region of the cladding layer is 185 Hv, and the nanohardness of the coarse-grained region is 141.5 Hv, which is much higher than the hardness of the substrate (about 118 Hv).

[0065] Example 5: Process Parameter Boundary Verification The only difference between this embodiment and Embodiment 1 is that: The infrared laser power was adjusted to 300 W, wavelength to 1100 nm, and spot diameter to 0.6 mm. The blue laser power was adjusted to 1000 W, wavelength to 470 nm, and spot diameter to 2.5 mm. The scanning speed was adjusted to 700 mm / s, and the powder feeding gas flow rate was adjusted to 20 L / min.

[0066] The CuZn40 powder has a particle size distribution of D10=55μm, D50=80μm, D90=110μm, and a loose packing density of 4.6g / cm³. 3 The tap density is 5.3 g / cm³. 3 .

[0067] When performing multi-pass cladding, the overlap rate between adjacent passes is 0.9 mm.

[0068] When performing multi-layer, multi-pass cladding, the thickness (layer height) of a single cladding layer is 1.2 mm.

[0069] The results showed that the molten pool boundary was clear and the metallurgical bonding was good.

[0070] In this embodiment, a copper-zinc alloy surface cladding layer is prepared by the above method. The cladding layer forms a dense metallurgical bond with the copper-zinc alloy substrate without cracks or pores. The cladding layer has a wavy texture structure parallel to the substrate direction. The peak region of the wavy texture is composed of fine equiaxed crystals (i.e., fine-grained region), and the trough region of the wavy texture is composed of columnar dendrites (i.e., coarse-grained region), which grow directionally in the opposite direction of heat flow.

[0071] Specifically, in this embodiment, the copper-zinc alloy surface cladding layer prepared by the above method forms a dense metallurgical bond with the copper-zinc alloy substrate without cracks or pores. The cladding layer has a wavy texture structure parallel to the substrate direction. The peak region of the wavy texture is composed of fine equiaxed crystals (i.e., fine-grained region) with an average grain size of about 2 μm. The trough region of the wavy texture is composed of columnar dendrites (i.e., coarse-grained region) that grow directionally in the opposite direction of heat flow. The nanohardness of the fine-grained region of the cladding layer is 160 Hv, and the nanohardness of the coarse-grained region is 140.2 Hv, which is much higher than the hardness of the substrate (about 118 Hv).

[0072] Example 6: Process Parameter Boundary Verification The only difference between this embodiment and Embodiment 1 is that the power of the blue laser is 600W.

[0073] Example 7: Process Parameter Boundary Verification The only difference between this embodiment and Embodiment 1 is that the power of the blue laser is 800W.

[0074] It should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the invention. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all the features of the foregoingly disclosed embodiments. Therefore, the claims, following the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0075] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and instructional purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement, characterized in that, include: The cladding CuZn coating forms a metallurgical bond with the copper-zinc alloy substrate; The clad CuZn coating has a wavy texture structure parallel to the direction of the copper-zinc alloy substrate. The wavy edges of the wavy texture are fine-grained regions; The interior of the wave-like texture is a coarse-grained region. The hardness of both the fine-grained region and the coarse-grained region is higher than that of the copper-zinc alloy matrix.

2. The CuZn coating cladding on the surface of a copper-zinc alloy based on red-blue laser synergistic enhancement as described in claim 1, characterized in that, The fine-grained region consists of small equiaxed crystals with an average grain size of 1-2 μm; the coarse-grained region consists of columnar crystals distributed within the wavy texture structure, which grow directionally in the opposite direction of heat flow.

3. The CuZn coating cladding on the surface of a copper-zinc alloy based on red-blue laser synergistic enhancement as described in claim 1, characterized in that, The nanohardness of the fine-grained region is 160-193.4 Hv; the nanohardness of the coarse-grained region is 140.2-150.4 Hv.

4. A method for preparing a CuZn coating clad on a copper-zinc alloy surface based on red-blue laser synergistic enhancement, according to any one of claims 1-3, characterized in that, Includes the following steps: CuZn40 powder was fused onto a CuZn substrate using a coaxial composite infrared laser and a blue laser. The infrared laser has a power of 100-300 W, a wavelength of 1000-1100 nm, and a spot diameter of 0.3-0.6 mm. The blue laser has a power of 500-1000 W, a wavelength of 430-470 nm, and a spot diameter of 1.5-2.5 mm. The diameter of the infrared laser spot is smaller than the diameter of the blue laser spot. The scanning speed is 300-700 mm / s; The powder delivery gas flow rate is 10-20 L / min; The cladding process is carried out in an inert protective atmosphere, with the oxygen content controlled below 200 ppm; When performing multi-pass cladding, the overlap rate between adjacent passes is 0.7-0.9 mm; When performing multi-layer, multi-pass cladding, the thickness of a single cladding layer is 0.8-1.2 mm.

5. The preparation method according to claim 4, characterized in that, The particle size distribution of CuZn40 powder is D10=40-55μm, D50=70-80 μm, and D90=100-110 μm.

6. The preparation method according to claim 4, characterized in that, The focal points of the infrared and blue lasers are aligned with the convergence point of the CuZn40 powder.

7. The preparation method according to claim 4, characterized in that, The infrared laser has a power of 200-300 W, and the blue laser has a power of 600-800 W; the infrared laser spot diameter is 0.4 mm, and the blue laser spot diameter is 1.75 mm; the scanning speed is 500 mm / s.

8. The application of a CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement, as described in any one of claims 1-3, on a high-zinc brass surface, characterized in that, High-zinc brass is H59 brass.

9. The application of a CuZn coating cladding on a copper-zinc alloy surface based on red-blue laser synergistic enhancement, as described in any one of claims 1-3, in copper alloy guide rails.

10. A copper alloy guide rail comprising a CuZn coating clad on the surface of a copper-zinc alloy based on red-blue laser synergistic enhancement, as described in any one of claims 1-3.

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