Laser cladding powder and method for laser cladding on surface of aluminum alloy

Abstract

The invention relates to the technical field of laser cladding, in particular to laser cladding powder and a method for laser cladding on the surface of aluminum alloy, and the laser cladding powder comprises 10-20 wt% of Ni, 2-5 wt% of Al, 2-5 wt% of Ti and the balance Cu; the method for laser cladding on the surface of the aluminum alloy comprises the steps that the laser cladding powder serves as a cladding raw material, and a cladding layer is formed on the surface of an aluminum alloy matrix through a positive out-of-focus cladding method; an intermetallic compound generated by the copper element and the aluminum element has high hardness and high wear resistance, the nickel element is dissolved in a copper alloy matrix to further enhance the hardness of the cladding layer, so that the hardness of the whole strengthened layer is improved, and the titanium element can improve the plasticity of the strengthened layer and prevent the whole coating from cracking and stripping.

Description

Technical Field

[0001] The invention relates to the technical field of laser cladding, and in particular to a laser cladding powder and a method for laser cladding on an aluminum alloy surface. Background Art

[0002] As a lightweight material, aluminum alloy has the characteristics of low density, high strength and high corrosion resistance, and has become a common material in the automotive industry, aerospace, marine engineering, power engineering and other fields. However, aluminum alloy materials usually have disadvantages such as low hardness and poor wear resistance, which limits the scope of application of aluminum alloy materials.

[0003] Laser cladding technology uses a high-energy laser beam to melt metal-based powder and a thin layer on the surface of the substrate, thereby forming a strengthening layer on the surface of the substrate, so that the surface of the substrate obtains excellent properties such as high hardness, high corrosion resistance, high wear resistance, and high conductivity.

[0004] Cladding a copper alloy strengthening layer on the surface of an aluminum alloy substrate can make the workpiece have both the high corrosion resistance of the aluminum alloy and the high hardness of the strengthening layer. During the laser cladding process, copper, nickel, and aluminum elements will produce intermetallic compounds, which can significantly increase the hardness of the cladding layer. However, the copper, nickel, and aluminum system often has the characteristics of high hardness and high brittleness, which can easily cause cracks and peeling of the coating, which has become an urgent problem to be solved in the preparation of a complete and crack-free copper alloy strengthening layer. Summary of the invention

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a laser cladding powder and a method for laser cladding on an aluminum alloy surface.

[0006] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: In one aspect, the present invention provides a laser cladding powder, comprising: 10-20wt% Ni, 2-5wt% Al and 2-5wt% Ti, with the remainder being Cu.

[0007] In some embodiments, the laser cladding powder is obtained by the following method: in an argon atmosphere, Ni, Al, Ti and Cu are ball-milled to obtain laser cladding powder.

[0008] In some embodiments, the ball milling speed is 200-400 r / min, and the ball milling time is 3-5 h.

[0009] In some embodiments, the laser cladding powder has a particle size of 45-150 μm and a purity of 99.99%.

[0010] Another invention, the present invention also provides a method for laser cladding on the surface of an aluminum alloy, the method for laser cladding on the surface of an aluminum alloy comprising: using the above-mentioned laser cladding powder as a cladding raw material, and adopting a positive defocusing cladding method to form a cladding layer on the surface of an aluminum alloy substrate, the laser power of the laser beam of the laser cladding is 7.5~10kW, and the defocus amount is 2~10mm.

[0011] In some embodiments, the cladding raw material is processed by the following method before cladding: Mix nickel powder, aluminum powder, titanium powder and copper powder, dry them and set aside.

[0012] In some embodiments, the drying temperature is 120° C., and the drying time is 2 to 3 hours.

[0013] In some embodiments, the aluminum alloy substrate is pretreated by the following method: grinding and removing impurities from the surface of the aluminum alloy substrate, ultrasonic cleaning, and drying for later use.

[0014] In some embodiments, the spot width formed by the laser beam on the surface of the aluminum alloy substrate is 20 mm, and the angle between the cladding head and the aluminum alloy substrate is 86-89°.

[0015] In some embodiments, the scanning speed of the positive defocusing cladding is 5-12 mm / s, the carrier gas pressure is 0.3-1 MPa, and the powder feeding amount is 45-90 g / min.

[0016] The beneficial effects of the present invention are: 1. The intermetallic compound formed by copper and aluminum has high hardness and high wear resistance. The nickel element dissolved in the copper alloy matrix will further enhance the hardness of the cladding layer and improve the hardness of the overall strengthening layer. The titanium element will improve the plasticity of the strengthening layer and prevent the overall cracking and peeling of the coating.

[0017] 2. By using laser cladding copper alloy powder, the thickness of the high-hardness strengthening layer (cladding layer) can reach more than 0.5mm without cracks. The maximum hardness of the strengthening layer exceeds 400HV, and the hardness of the strengthening layer can reach 5 times that of the substrate.

[0018] 3. Compared with traditional copper alloy powder, the copper alloy powder used for laser cladding on the surface of aluminum alloy substrate in the present invention has the effect of solid solution strengthening on the coating and improves the hardness of the coating by adding Ni element to make it solid-dissolve in the copper alloy; by adding a small amount of intermetallic compound between Al element and Cu element, second phase particle strengthening is achieved, and the hardness of the copper alloy coating is further improved; by adding Ti element to improve the plasticity of the cladding layer, the cladding layer can be effectively prevented from cracking and peeling off from the aluminum alloy substrate.

[0019] 4. Compared with the traditional laser cladding method, the process method for preparing copper alloy coating by laser cladding on the surface of aluminum alloy in the present invention adopts a positive defocus laser cladding process to achieve early melting of copper alloy powder, so that it is deposited on the surface of aluminum alloy in the form of metal droplets, thereby reducing the melting depth of aluminum alloy and the thickness of the transition layer between copper and aluminum alloy, thereby achieving the preparation of crack-free and high-hardness copper alloy coating on the surface of aluminum alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the macroscopic morphology of the cladding layer of Example 1; Figure 2 The microstructure of the cladding layer of Example 1; Figure 3 The XRD result of the cladding layer of Example 1; Figure 4 is the microhardness of the cladding layer of Example 1; Figure 5 This is the macroscopic morphology of the cladding layer of Example 2; Figure 6 This is the microscopic morphology of the cladding layer of Example 2; Figure 7 The XRD result of the cladding layer of Example 2; Figure 8 is the microhardness of the cladding layer of Example 2; Fig. 9 This is the macroscopic morphology of the cladding layer of Example 3; Fig.10 The microstructure of the cladding layer of Example 3; Fig.11 XRD result of the cladding layer of Example 3; Fig.12 is the microhardness of the cladding layer of Example 3; Fig.13 This is the macroscopic morphology of the cladding layer of Example 4; Fig.14 is the microhardness of the cladding layer of Example 4; Fig.15 This is the macroscopic morphology of the cladding layer of Example 5; Fig.16 is the microhardness of the cladding layer of Example 5; Fig.17 This is the macroscopic morphology of the cladding layer of Comparative Example 1; Fig.18 This is the macroscopic morphology of the cladding layer of Comparative Example 2. DETAILED DESCRIPTION

[0021] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

[0022] At present, copper, nickel and aluminum systems often have the characteristics of high hardness and high brittleness, which easily cause cracks and peeling of the coating. This has become an urgent problem to be solved in the preparation of a complete and crack-free copper alloy strengthening layer.

[0023] In one aspect, the present invention provides a laser cladding powder, comprising: 10-20wt% Ni, 2-5wt% Al and 2-5wt% Ti, with the remainder being Cu.

[0024] Exemplarily, Ni can be any one of 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, and 20wt%, or a range value between any two of them, which is not specifically limited in the embodiments of the present application.

[0025] For example, Al may be any one of 2wt%, 3wt%, 4wt%, and 5wt%, or a range value between any two of them, which is not specifically limited in the embodiments of the present application.

[0026] For example, Ti may be any one of 2wt%, 3wt%, 4wt%, and 5wt%, or a range of values ​​between any two of them, which is not specifically limited in the embodiments of the present application.

[0027] The total content of the components of the laser cladding powder defined above: Ni, Al, Ti and Cu is 100wt%.

[0028] In some embodiments, the laser cladding powder is obtained by the following method: in an argon atmosphere, Ni, Al, Ti and Cu are ball-milled to obtain laser cladding powder, and argon is used to prevent oxygen in the air from oxidizing Ni, Al, Ti and Cu.

[0029] In some embodiments, the ball milling speed is 200-400 r / min, and the ball milling time is 3-5 h.

[0030] In some embodiments, the laser cladding powder has a particle size of 45-150 μm and a purity of 99.99%.

[0031] Another invention, the present invention also provides a method for laser cladding on the surface of an aluminum alloy, the method for laser cladding on the surface of an aluminum alloy comprising: using the above-mentioned laser cladding powder as a cladding raw material, and adopting a positive defocusing cladding method to form a cladding layer on the surface of an aluminum alloy substrate, the laser power of the laser beam of the laser cladding is 7.5~10kW, and the defocus amount is 2~10mm.

[0032] Exemplarily, the laser power may be any point value of 7.5 kW, 8 kW, 8.5 kW, 9 kW, 9.5 kW, and 10 kW, or a range value between any two of them, which is not specifically limited in the embodiments of the present application.

[0033] Exemplarily, the defocus amount can be any point value of 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, and 10mm, or a range value between any two of them, which is not specifically limited in the embodiments of the present application.

[0034] In some embodiments, the cladding raw material is processed by the following method before cladding: Mix nickel powder, aluminum powder, titanium powder and copper powder, dry them and set aside.

[0035] In some embodiments, the drying temperature is 120° C., and the drying time is 2 to 3 hours.

[0036] In some embodiments, the aluminum alloy substrate is pretreated by the following method: grinding and removing impurities from the surface of the aluminum alloy substrate, ultrasonic cleaning, and drying for later use.

[0037] In some embodiments, the spot width formed by the laser beam on the surface of the aluminum alloy substrate is 20 mm, and the angle between the cladding head and the aluminum alloy substrate is 86-89°.

[0038] Exemplarily, the angle may be any point value of 86°, 87°, 88°, 89°, or a range value between any two of them, which is not specifically limited in the embodiments of the present application.

[0039] In some embodiments, the scanning speed of the positive defocusing cladding is 5-12 mm / s, the carrier gas pressure is 0.3-1 MPa, and the powder feeding amount is 45-90 g / min.

[0040] Exemplarily, the scanning speed can be any point value of 5mm / s, 6mm / s, 7mm / s, 8mm / s, 9mm / s, 10mm / s, 11mm / s, and 12mm / s, or a range value between any two of them, which is not specifically limited in the embodiments of the present application.

[0041] For example, the carrier gas pressure may be any point value of 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, or a range value between any two of them, which is not specifically limited in the embodiments of the present application.

[0042] Exemplarily, the powder feeding amount can be any one of 45g / min, 46g / min, 47g / min, 49g / min, 50g / min, 52g / min, 56g / min, 58g / min, 60g / min, 65g / min, 70g / min, 75g / min, 80g / min, 82g / min, 86g / min, 88g / min, and 90g / min, or a range value between any two of them, which is not specifically limited in the embodiments of the present application.

[0043] The intermetallic compound generated by copper and aluminum elements has high hardness and high wear resistance. The nickel element dissolved in the copper alloy matrix will further enhance the hardness of the cladding layer and improve the hardness of the overall strengthening layer. The titanium element will increase the plasticity of the strengthening layer and prevent the overall cracking and peeling of the coating.

[0044] By using laser cladding copper alloy powder, the thickness of the high-hardness strengthening layer can reach more than 0.5mm without any cracks. The maximum hardness of the strengthening layer exceeds 400HV, and the hardness of the strengthening layer can reach 5 times that of the substrate.

[0045] Compared with traditional copper alloy powder, the copper alloy powder for laser cladding on the surface of an aluminum alloy substrate in the present invention has a solid solution strengthening effect on the coating by adding Ni element to make it solid-dissolved in the copper alloy, thereby improving the hardness of the coating; a small amount of intermetallic compound is formed between the Al element and the Cu element, thereby realizing second phase particle strengthening and further improving the hardness of the copper alloy coating; and the plasticity of the cladding layer is improved by adding Ti element, which can effectively prevent the cladding layer from cracking and peeling off from the aluminum alloy substrate.

[0046] Compared with the traditional laser cladding method, the process method for preparing a copper alloy coating by laser cladding on the surface of an aluminum alloy in the present invention adopts a positive defocus laser cladding process to achieve early melting of the copper alloy powder, so that it is deposited on the surface of the aluminum alloy in the form of molten metal droplets, thereby reducing the melting depth of the aluminum alloy and the thickness of the transition layer between the copper and aluminum alloys, thereby achieving the preparation of a crack-free and high-hardness copper alloy coating on the surface of the aluminum alloy.

[0047] In order to objectively evaluate the technical effects of the embodiments of the present disclosure, the technical solutions provided by the present disclosure will be described in detail and exemplarily through experimental examples below.

[0048] In order to make the present application easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are only for illustration and are not intended to limit the scope of application of the present invention.

[0049] Unless otherwise specified, the operations and processing methods involved in this application are conventional methods in the art.

[0050] Unless otherwise specified, the instruments used in this application are conventional instruments in the art.

[0051] Example 1 Example 1 of the present application provides a laser cladding powder including a Cu content of 79wt%, a Ni content of 15wt%, an Al content of 3wt%, and a Ti content of 3wt%. The laser cladding powder is obtained by ball milling, wherein the ball milling speed is 250r / min, the ball milling time is 4h, and the ball milling atmosphere is argon.

[0052] Embodiment 1 of the present application also provides a method for laser cladding on the surface of an aluminum alloy, comprising the following steps: 1) Before laser cladding, the mixed laser cladding powder was kept at 120°C for 3 hours in a vacuum drying oven to remove moisture; 2) Pretreatment of aluminum alloy substrate: Use an angle grinder to grind the surface of the aluminum alloy substrate to make it smooth and remove the oxide layer, then perform ultrasonic cleaning to remove oil stains, and blow dry for later use; 3) A high hardness cladding layer was prepared on the surface of the aluminum alloy substrate by coaxial powder feeding using a 20000W wide spot laser processing system (i.e., a wide spot laser was formed on the surface of the aluminum alloy substrate by a positive defocus cladding method, and laser cladding powder was coaxially provided to the surface of the aluminum alloy substrate, and the laser cladding powder was melted by the wide spot laser to prepare a high hardness strengthening layer on the surface of the aluminum alloy substrate), wherein the spot width was 20mm, the defocus amount was 5mm, the angle between the cladding head and the aluminum alloy substrate was 87°, the laser power of the laser beam for laser cladding was 8000W, the laser cladding scanning speed was 10mm / s, the carrier gas pressure was 0.3MPa, and the powder feeding amount was 60g / min.

[0053] The macroscopic morphology of the obtained cladding layer was observed. Figure 1 As shown in the figure, the cladding layer is complete without cracks or peeling, and the coating thickness can reach more than 0.5 mm. Figure 2 As shown, the coating mainly has a dendritic morphology, and there are a small amount of gray needle-shaped and irregular bright white precipitates. According to the EDS results, point 1 (gray needle-shaped phase) mainly contains aluminum and titanium elements, point 2 (bright white phase) mainly contains aluminum, copper, and nickel elements, point 3 (black phase) mainly contains aluminum and a small amount of copper elements, and point 4 (dendritic phase) mainly contains aluminum and a small amount of copper elements, as shown in Table 1 below.

[0054] Table 1 according to Figure 3 The XRD results show that the gray needle-like phase contains Al and Ti, and the bright white precipitate phase is Al7Cu4Ni. The hardness test results are as follows Figure 4 As shown, its maximum hardness exceeds 400HV, which is 5 times that of the matrix.

[0055] Example 2 Example 2 of the present application provides a laser cladding powder including a Cu content of 86wt%, a Ni content of 10wt%, an Al content of 2wt%, and a Ti content of 2wt%. The laser cladding powder is obtained by ball milling, wherein the ball milling speed is 250r / min, the ball milling time is 4h, and the ball milling atmosphere is argon.

[0056] Example 2 of the present application also provides a method for laser cladding on the surface of an aluminum alloy, which is the same as Example 1.

[0057] The macroscopic morphology of the obtained cladding layer was observed. Figure 5 As shown in the figure, the cladding layer is complete without cracks or peeling, and the coating thickness can reach more than 0.5 mm. Figure 6 As shown, the coating mainly has a dendritic morphology, and there are a small amount of gray needle-shaped and irregular bright white precipitates. According to the EDS results, point 5 (gray needle-shaped phase) mainly contains aluminum and titanium elements, point 6 (black phase) mainly contains aluminum and a small amount of copper elements, point 7 (bright white phase) mainly contains aluminum, copper, and nickel elements, and point 8 (dendritic phase) mainly contains aluminum and a small amount of copper elements, as shown in Table 2 below.

[0058] Table 2 according to Figure 7 The XRD results show that the gray needle-like phase contains Al and Ti, and the bright white precipitate phase is Al7Cu4Ni. The hardness test results are as follows Figure 8 As shown, its maximum hardness exceeds 400HV, which is 5 times that of the matrix.

[0059] Example 3 Example 3 of the present application provides a laser cladding powder including a Cu content of 70wt%, a Ni content of 20wt%, an Al content of 5wt%, and a Ti content of 5wt%. The laser cladding powder is obtained by ball milling, wherein the ball milling speed is 250r / min, the ball milling time is 4h, and the ball milling atmosphere is argon.

[0060] Example 3 of the present application also provides a method for laser cladding on the surface of an aluminum alloy, which is the same as Example 1.

[0061] The macroscopic morphology of the obtained cladding layer was observed. Fig. 9 As shown in the figure, the cladding layer is complete without cracks or peeling, and the coating thickness can reach more than 0.5 mm. Fig.10 As shown, the coating mainly has a dendritic morphology, and there are a small amount of gray needle-shaped and irregular bright white precipitates. According to the EDS results, point 9 (gray needle-shaped phase) mainly contains aluminum and titanium elements, point 10 (black phase) mainly contains aluminum and a small amount of copper elements, point 11 (bright white phase) mainly contains aluminum, copper, and nickel elements, and point 12 (dendritic phase) mainly contains aluminum and a small amount of copper elements, as shown in Table 3.

[0062] Table 3 according to Fig.11 The XRD results show that the gray needle-like phase contains Al and Ti, and the bright white precipitate phase is Al7Cu4Ni. The hardness test results are as follows Fig.12 As shown, its maximum hardness exceeds 400HV, which is 5 times that of the matrix.

[0063] Example 4 Example 4 of the present application is the same as Example 1, except that the defocus amount is 10 mm, the angle between the cladding head and the aluminum alloy substrate is 86°, the laser power of the laser beam for laser cladding is 7500 W, and the laser cladding scanning speed is 5 mm / s.

[0064] The macroscopic morphology of the obtained cladding layer was observed. Fig.13 As shown, the cladding layer is complete without cracks or peeling, and the coating thickness can reach more than 0.5mm. The hardness test results are as follows Fig.14 As shown, its maximum hardness exceeds 370HV, which is more than 4 times that of the matrix.

[0065] Example 5 Example 5 of the present application is the same as Example 1, except that the defocus amount is 2 mm, the angle between the cladding head and the aluminum alloy substrate is 86°, the laser power of the laser beam for laser cladding is 10000 W, and the laser cladding scanning speed is 5 mm / s.

[0066] The macroscopic morphology of the obtained cladding layer was observed. Fig.15 As shown, the cladding layer is complete without cracks or peeling, and the coating thickness can reach more than 0.5mm. The hardness test results are as follows Fig.16 As shown, its maximum hardness exceeds 400HV, which is 5 times that of the matrix.

[0067] Comparative Example 1 Comparative Example 1 provides a laser cladding powder including a Cu content of 100 wt %, and the laser cladding powder is obtained by ball milling, wherein the ball milling speed is 250 r / min, the ball milling time is 4 h, and the ball milling atmosphere is argon.

[0068] Comparative Example 1 also provides a method for laser cladding on the surface of an aluminum alloy, which is the same as Example 1. The macroscopic morphology of the obtained cladding layer is observed, such as Fig.17 As shown, cracks appeared in the cladding layer.

[0069] Comparative Example 2 This comparative example is the same as Example 1, except that the defocus amount is 0 mm, the angle between the cladding head and the aluminum alloy substrate is 85°, the laser power of the laser beam for laser cladding is 12000 W, and the laser cladding scanning speed is 15 mm / s.

[0070] The macroscopic morphology of the obtained coating was observed. Fig.18 As shown, cracks appeared in the cladding layer.

[0071] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0072] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A laser cladding powder, characterized in that: The laser cladding powder comprises: 10-20wt% Ni, 2-5wt% Al and 2-5wt% Ti, and the balance is Cu.

2. The laser cladding powder according to claim 1, characterized in that: The laser cladding powder is obtained by the following method: in an argon atmosphere, Ni, Al, Ti and Cu are ball-milled to obtain the laser cladding powder.

3. The laser cladding powder according to claim 2, characterized in that: The ball mill has a rotation speed of 200-400 r / min and a ball milling time of 3-5 h.

4. The laser cladding powder according to claim 2, characterized in that: The particle size of the laser cladding powder is 45-150 μm, and the purity is 99.99%.

5. A method for laser cladding on an aluminum alloy surface, characterized in that: The method for laser cladding on the surface of an aluminum alloy comprises: using the laser cladding powder described in any one of claims 1 to 4 as a cladding raw material, and adopting a positive defocusing cladding method to form a cladding layer on the surface of an aluminum alloy substrate, the laser power of the laser beam of the laser cladding is 7.5 to 10 kW, and the defocus amount is 2 to 10 mm.

6. The method according to claim 5, characterized in that The cladding raw material is processed by the following method before cladding: Mix nickel powder, aluminum powder, titanium powder and copper powder, dry them and set aside.

7. The method according to claim 6, characterized in that The drying temperature is 120° C., and the drying time is 2 to 3 hours.

8. The method according to claim 5, characterized in that The aluminum alloy substrate is pretreated by the following method: grinding and removing impurities from the surface of the aluminum alloy substrate, ultrasonic cleaning, and drying for later use.

9. The method according to claim 5, characterized in that The spot width formed by the laser beam on the surface of the aluminum alloy substrate is 20 mm, and the angle between the cladding head and the aluminum alloy substrate is 86-89°.

10. The method according to claim 5, characterized in that The scanning speed of the positive defocusing cladding is 5-12 mm / s, the carrier gas pressure is 0.3-1 MPa, and the powder feeding amount is 45-90 g / min.

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