A laser cladding powder and a method for laser cladding on an aluminum alloy surface

Abstract

The present application relates to the technical field of laser cladding, and particularly relates to a laser cladding powder and a method for laser cladding on an aluminum alloy surface, the laser cladding powder comprising 10-20 wt% Ni, 2-5 wt% Al and 2-5 wt% Ti, and the balance being Cu; the method for laser cladding on the aluminum alloy surface comprising: taking the 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 base body; the intermetallic compound generated by the copper element and the aluminum element has high hardness and high wear resistance, the solid solution of the nickel element in the copper alloy base body can further enhance the hardness of the cladding layer, the overall strengthened layer hardness is improved, and the titanium element can improve the plasticity of the strengthened layer, thereby preventing the overall coating from cracking and peeling off.

Description

TECHNICAL FIELD

[0001] The present application 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

[0002] Aluminum alloy, as a light material, has the characteristics of low density, high strength, and high corrosion resistance, and has become a commonly used material in the fields of automobile industry, aerospace, marine engineering, and power engineering. However, aluminum alloy materials generally have the disadvantages of low hardness and poor wear resistance, which limits the application range of aluminum alloy materials.

[0003] Laser cladding technology is a technology that uses a high-energy laser beam to melt a metal-based powder and a thin layer on the surface of a substrate, thereby forming a strengthening layer on the surface of the substrate, so that the surface of the substrate has excellent properties such as high hardness, high corrosion resistance, high wear resistance, and high electrical 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 aluminum alloy and the high hardness of the strengthening layer. During the laser cladding process, intermetallic compounds of copper, nickel, and aluminum are produced, which can significantly improve 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 is a problem that needs to be solved for preparing a complete and crack-free copper alloy strengthening layer. SUMMARY

[0005] To solve the above technical problems, embodiments of the present application provide a laser cladding powder and a method for laser cladding on an aluminum alloy surface.

[0006] To achieve the above-mentioned purpose, embodiments of the present application adopt the following technical solutions:

[0007] On the one hand, the present application provides a laser cladding powder, which comprises 10-20wt% Ni, 2-5wt% Al, and 2-5wt% Ti, and the balance of Cu.

[0008] In some embodiments, the laser cladding powder is obtained by ball milling Ni, Al, Ti, and Cu in an argon atmosphere.

[0009] In some embodiments, the rotation speed of the ball milling is 200-400r / min, and the ball milling time is 3-5h.

[0010] In some embodiments, the particle size of the laser cladding powder is 45-150μm, and the purity is 99.99%.

[0011] Another application, the application also provides a method for laser cladding on the surface of an aluminum alloy, the method comprising: using the laser cladding powder as a cladding raw material, and forming a cladding layer on the surface of an aluminum alloy base by a positive defocusing cladding method, wherein the laser power of the laser beam for laser cladding is 7.5-10 kW, and the defocusing amount is 2-10 mm.

[0012] In some embodiments, the cladding raw material is treated by the following method before cladding:

[0013] The nickel powder, aluminum powder, titanium powder and copper powder are mixed and dried for standby use.

[0014] In some embodiments, the drying temperature is 120 DEG C, and the drying time is 2-3 h.

[0015] In some embodiments, the pretreatment of the aluminum alloy base is performed by the following method: the surface of the aluminum alloy base is polished and cleaned, ultrasonic cleaning is performed, and then drying is performed for standby use.

[0016] In some embodiments, the laser beam forms a spot width of 20 mm on the surface of the aluminum alloy base, and the angle between the cladding head and the aluminum alloy base is 86-89 DEG.

[0017] 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.

[0018] The application has the following beneficial effects:

[0019] 1. The intermetallic compound formed by the copper element and the aluminum element has high hardness and high wear resistance, the solid solution of the nickel element in the copper alloy base can further enhance the hardness of the cladding layer, the plasticity of the strengthened layer is improved by the titanium element, and the overall cracking and peeling of the coating are prevented.

[0020] 2. The laser cladding copper alloy powder is used, the thickness of the high-hardness strengthened layer (cladding layer) can reach more than 0.5 mm, and no cracks are generated, the maximum hardness of the strengthened layer is more than 400 HV, and the hardness of the strengthened layer can be 5 times that of the base.

[0021] 3. Compared with the traditional copper alloy powder, the laser cladding copper alloy powder used in the application for the surface of an aluminum alloy base is added with Ni elements to be solid-solved in the copper alloy, thereby producing a solid solution strengthening effect on the coating and improving the hardness of the coating; a small amount of intermetallic compound is formed between the Al elements and the Cu elements, thereby realizing second-phase particle strengthening and further improving the hardness of the copper alloy coating; the Ti elements are added to improve the plasticity of the cladding layer, which can effectively prevent the generation of cracks in the cladding layer and the peeling from the aluminum alloy base.

[0022] 4. The process for preparing a laser cladding copper alloy coating on the surface of an aluminum alloy according to the present application, compared with the traditional laser cladding method, realizes the early melting of the copper alloy powder by using the positive defocusing laser cladding process, so that the copper alloy powder is deposited on the surface of the aluminum alloy in the form of metal droplets, thereby reducing the melting depth of the aluminum alloy and the thickness of the transition layer between the copper and aluminum alloys, and realizing the preparation of a crack-free high-hardness copper alloy coating on the surface of the aluminum alloy. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Macro morphology of the cladding layer of Example 1;

[0024] Figure 2 Micro morphology of the cladding layer of Example 1;

[0025] Figure 3 XRD result of the cladding layer of Example 1;

[0026] Figure 4 Micro hardness of the cladding layer of Example 1;

[0027] Figure 5 Macro morphology of the cladding layer of Example 2;

[0028] Figure 6 Micro morphology of the cladding layer of Example 2;

[0029] Figure 7 XRD result of the cladding layer of Example 2;

[0030] Figure 8 Micro hardness of the cladding layer of Example 2;

[0031] Figure 9 Macro morphology of the cladding layer of Example 3;

[0032] Figure 10 Micro morphology of the cladding layer of Example 3;

[0033] Figure 11 XRD result of the cladding layer of Example 3;

[0034] Figure 12 Micro hardness of the cladding layer of Example 3;

[0035] Figure 13 Macro morphology of the cladding layer of Example 4;

[0036] Figure 14 Micro hardness of the cladding layer of Example 4;

[0037] Figure 15 Macro morphology of the cladding layer of Example 5;

[0038] Figure 16Microhardness of the cladding layer of Example 5;

[0039] Figure 17 Macro morphology of the cladding layer of Comparative Example 1;

[0040] Figure 18 Macro morphology of the cladding layer of Comparative Example 2. DETAILED DESCRIPTION

[0041] The technical solutions in some embodiments of the present disclosure will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided in the present disclosure, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present disclosure.

[0042] At present, the copper, nickel and aluminum systems often have the characteristics of high hardness and high brittleness, which can easily cause cracks and peeling of the coating, which becomes a problem to be solved for preparing a complete copper alloy strengthening layer without cracks.

[0043] In one aspect, the present application provides a laser cladding powder, which comprises 10-20wt% Ni, 2-5wt% Al and 2-5wt% Ti, and the balance of Cu.

[0044] Exemplarily, the Ni can be any one of 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, or a range value between any two of them, and the embodiments of the present application do not make specific limitations thereon.

[0045] Exemplarily, the Al can be any one of 2wt%, 3wt%, 4wt%, 5wt%, or a range value between any two of them, and the embodiments of the present application do not make specific limitations thereon.

[0046] Exemplarily, the Ti can be any one of 2wt%, 3wt%, 4wt%, 5wt%, or a range value between any two of them, and the embodiments of the present application do not make specific limitations thereon.

[0047] The laser cladding powder defined above: the total content of the components of Ni, Al, Ti and Cu is 100wt%.

[0048] In some embodiments, the laser cladding powder is obtained by the following method: Ni, Al, Ti and Cu are ball milled to obtain a laser cladding powder in an argon atmosphere, and the argon avoids the oxidation of Ni, Al, Ti and Cu by oxygen in the air.

[0049] In some embodiments, the rotation speed of the ball mill is 200-400 r / min, and the ball milling time is 3-5 h.

[0050] In some embodiments, the particle size of the laser cladding powder is 45-150 pm, and the purity is 99.99%.

[0051] Another application, the application also provides a method for laser cladding on an aluminum alloy surface, which comprises: using the above laser cladding powder as a cladding raw material, and using a positive defocusing cladding method to form a cladding layer on the surface of an aluminum alloy substrate, wherein the laser power of the laser beam for laser cladding is 7.5-10 kW, and the defocusing amount is 2-10 mm.

[0052] Illustratively, the laser power can be a point value of any one of 7.5 kW, 8 kW, 8.5 kW, 9 kW, 9.5 kW, 10 kW or a range value between any two of them, for which the embodiments of the present application are not specifically limited.

[0053] Illustratively, the defocusing amount can be a point value of any one of 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or a range value between any two of them, for which the embodiments of the present application are not specifically limited.

[0054] In some embodiments, the cladding raw material is treated before cladding using the following method:

[0055] The nickel powder, aluminum powder, titanium powder and copper powder are mixed and dried for standby use.

[0056] In some embodiments, the drying temperature is 120°C, and the drying time is 2-3 h.

[0057] In some embodiments, the pretreatment of the aluminum alloy substrate uses the following method: the surface of the aluminum alloy substrate is polished and cleaned, ultrasonic cleaned, dried and standby used.

[0058] In some embodiments, the laser beam forms a spot width of 20 mm on the surface of the aluminum alloy substrate, and the included angle between the cladding head and the aluminum alloy substrate is 86-89°.

[0059] Illustratively, the included angle can be a point value of any one of 86°, 87°, 88°, 89° or a range value between any two of them, for which the embodiments of the present application are not specifically limited.

[0060] 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.

[0061] Exemplarily, the scanning speed can be a point value of any one of 5 mm / s, 6 mm / s, 7 mm / s, 8 mm / s, 9 mm / s, 10 mm / s, 11 mm / s, 12 mm / s or a range value between any two of them, and the embodiments of the present application are not limited specifically.

[0062] Exemplarily, the carrier gas pressure can be a point value of any one 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, and the embodiments of the present application are not limited specifically.

[0063] Exemplarily, the powder feeding amount can be a point value of any one of 45 g / min, 46 g / min, 47 g / min, 49 g / min, 50 g / min, 52 g / min, 56 g / min, 58 g / min, 60 g / min, 65 g / min, 70 g / min, 75 g / min, 80 g / min, 82 g / min, 86 g / min, 88 g / min, 90 g / min or a range value between any two of them, and the embodiments of the present application are not limited specifically.

[0064] The intermetallic compound generated by the copper element and the aluminum element has high hardness and high wear resistance, the solid solution of the nickel element in the copper alloy matrix can further enhance the hardness of the cladding layer, so that the overall strengthened layer hardness is improved, and the titanium element can improve the plasticity of the strengthened layer to prevent the overall coating from cracking and peeling off.

[0065] The high-hardness strengthened layer has a thickness of more than 0.5 mm and no cracks are generated, and the maximum hardness of the strengthened layer is more than 400 HV, and the hardness of the strengthened layer can be 5 times that of the substrate.

[0066] Compared with the traditional copper alloy powder, the copper alloy powder for laser cladding on the surface of the aluminum alloy substrate in the application is added with the Ni element to be solid-solved in the copper alloy, so as to produce the solid solution strengthening effect on the coating and improve the hardness of the coating; a small amount of intermetallic compound is formed between the Al element and the Cu element, so as to realize the second phase particle strengthening and further improve the hardness of the copper alloy coating; and the Ti element is added to improve the plasticity of the cladding layer, so as to effectively prevent the generation of cracks in the cladding layer and the peeling off from the aluminum alloy substrate.

[0067] Compared with the traditional laser cladding method, the preparation process method of the copper alloy coating for laser cladding on the surface of the aluminum alloy in the application adopts the positive defocusing laser cladding process, realizes the early melting of the copper alloy powder, makes the copper alloy powder in the form of metal droplets deposited on the surface of the aluminum alloy, thereby reducing the melting depth of the aluminum alloy and the thickness of the transition layer between the copper and aluminum alloys, and realizing the preparation of the crack-free high-hardness copper alloy coating on the surface of the aluminum alloy.

[0068] 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 by experimental examples.

[0069] In order to make the present application easier to understand, the present application will be described in detail below in conjunction with embodiments, which are only illustrative and do not limit the scope of application of the present application.

[0070] Unless otherwise specified, the operation and processing method involved in the present application belongs to the conventional method in the art.

[0071] Unless otherwise specified, the instruments used in the present application are conventional instruments in the art.

[0072] Embodiment 1

[0073] The embodiment 1 of the present application provides a laser cladding powder, which comprises Cu content of 79wt%, Ni content of 15wt%, Al content of 3wt%, and Ti content of 3wt%, and is obtained by a ball milling method, wherein the ball milling speed is 250r / min, the ball milling time is 4h, and the ball milling atmosphere is argon.

[0074] The embodiment 1 of the present application also provides a method for laser cladding on the surface of an aluminum alloy, comprising the following steps:

[0075] 1) Before laser cladding, the mixed laser cladding powder is placed in a vacuum drying box and kept at 120℃ for 3h to remove moisture;

[0076] 2) Pretreatment of the aluminum alloy substrate: the surface of the aluminum alloy substrate is polished smooth using an angle grinder to remove the oxide layer, and then ultrasonic cleaning is performed to remove oil stains, and the aluminum alloy substrate is blown dry for standby;

[0077] 3) A high-hardness cladding layer is prepared on the surface of the aluminum alloy substrate using a 20000W wide-beam laser processing system coaxial powder feeding method (i.e. a wide-beam laser is formed on the surface of the aluminum alloy substrate by the method of positive defocusing cladding, and at the same time, laser cladding powder is provided coaxially to the surface of the aluminum alloy substrate, and the wide-beam laser melts the laser cladding powder to prepare a high-hardness strengthening layer on the surface of the aluminum alloy substrate), wherein the spot width is 20mm, the defocusing amount is 5mm, the angle between the cladding head and the aluminum alloy substrate is 87°, the laser power of the laser beam for laser cladding is 8000W, the laser cladding scanning speed is 10mm / s, the carrier gas pressure is 0.3MPa, and the powder feeding amount is 60g / min.

[0078] The obtained cladding layer is observed for macroscopic morphology, as shown in Figure 1 , the cladding layer is complete without cracks and peeling, and the coating thickness can reach more than 0.5mm. Microstructure observation is performed thereon, as shown in Figure 2As shown in FIG. 2, the coating mainly has dendritic morphology, and a small amount of gray needle-like and irregular bright white precipitates. According to the EDS results, point 1 (gray needle-like 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.

[0079] Table 1

[0080]

[0081] According to the XRD results of Figure 3 , the gray needle-like phase contains Al and Ti, and the bright white precipitate phase is Al7Cu4Ni. The hardness test results are shown in Figure 4 , and the highest hardness is more than 400 HV, which is 5 times that of the substrate.

[0082] Example 2

[0083] The embodiment 2 of the present application provides a laser cladding powder, which comprises Cu content of 86wt%, Ni content of 10wt%, Al content of 2wt%, and Ti content of 2wt%. The laser cladding powder is obtained by a ball milling method, wherein the ball milling speed is 250r / min, the ball milling time is 4h, and the ball milling atmosphere is argon.

[0084] The embodiment 2 of the present application also provides a method for laser cladding on the surface of an aluminum alloy, which is the same as that of the embodiment 1.

[0085] The obtained cladding layer is subjected to macroscopic morphology observation, as shown in Figure 5 , the cladding layer is complete without cracks and peeling, and the coating thickness can reach more than 0.5mm. The microstructure observation is carried out, as shown in Figure 6 , the coating mainly has dendritic morphology, and a small amount of gray needle-like and irregular bright white precipitates. According to the EDS results, point 5 (gray needle-like 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.

[0086] Table 2

[0087]

[0088] According to the XRD results of Figure 7 , the gray needle-like phase contains Al and Ti, and the bright white precipitate phase is Al7Cu4Ni. The hardness test results are shown in Figure 8 , and the highest hardness is more than 400 HV, which is 5 times that of the substrate.

[0089] Example 3

[0090] The example 3 of the present application provides a laser cladding powder comprising Cu content of 70wt%, Ni content of 20wt%, Al content of 5wt%, and Ti content of 5wt%, wherein the laser cladding powder is obtained by a ball milling method, wherein the ball milling rotation speed is 250r / min, the ball milling time is 4h, and the ball milling atmosphere is argon.

[0091] The 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 the example 1.

[0092] The obtained cladding layer is observed in macro morphology, as shown in Figure 9 , the cladding layer is complete without cracks and peeling, and the coating thickness can reach more than 0.5mm. The microstructure observation is carried out, as shown in Figure 10 , the coating mainly has dendritic morphology, and 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.

[0093] Table 3

[0094]

[0095] According to the XRD results of Figure 11 , the gray needle-shaped phase contains Al and Ti, and the bright white precipitate phase is Al7Cu4Ni. The hardness test is carried out, and the results are shown in Figure 12 , and the highest hardness is more than 400HV, which is 5 times of the substrate.

[0096] Example 4

[0097] The example 4 of the present application is the same as the example 1, except that the defocusing amount is 10mm, the angle between the cladding head and the aluminum alloy substrate is 86°, the laser power of the laser beam for laser cladding is 7500W, and the laser cladding scanning speed is 5mm / s.

[0098] The obtained cladding layer is observed in macro morphology, as shown in Figure 13 , the cladding layer is complete without cracks and peeling, and the coating thickness can reach more than 0.5mm. The hardness test is carried out, and the results are shown in Figure 14 , and the highest hardness is more than 370HV, which is more than 4 times of the substrate.

[0099] Example 5

[0100] Embodiment 5 of the present application is the same as Embodiment 1, except that the defocusing 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.

[0101] The obtained cladding layer was observed for macro-morphology, as shown in FIG. 1, the cladding layer was complete without cracks or peeling, and the coating thickness could be more than 0.5 mm. Figure 15 The hardness of the cladding layer was tested, and the results are shown in FIG. 2. Figure 16 The highest hardness was more than 400 HV, which was 5 times of the substrate.

[0102] Comparative Example 1

[0103] Comparative Example 1 provides a laser cladding powder comprising Cu content of 100 wt%, and the laser cladding powder is obtained by a ball milling method, wherein the ball milling rotation speed is 250 r / min, the ball milling time is 4 h, and the ball milling atmosphere is argon.

[0104] Comparative Example 1 also provides a method for laser cladding on the surface of an aluminum alloy, which is the same as Embodiment 1. The obtained cladding layer was observed for macro-morphology, as shown in FIG. 1, cracks appeared in the cladding layer. Figure 17

[0105] Comparative Example 2

[0106] The present comparative example is the same as Embodiment 1, except that the defocusing 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.

[0107] The obtained coating was observed for macro-morphology, as shown in FIG. 1, cracks appeared in the cladding layer. Figure 18

[0108] In the description of the present specification, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0109] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.​​

Claims

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

2. The laser cladding powder of claim 1, wherein, The laser cladding powder is obtained by ball milling Ni, Al, Ti and Cu in an argon atmosphere.

3. The laser cladding powder of claim 2, wherein, The rotation speed of the ball milling is 200-400 r / min, and the ball milling time is 3-5 h.

4. The laser cladding powder of claim 2, wherein, The particle size of the laser cladding powder is 45-150 µm, and the purity is 99.99%.

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

6. The method of claim 5, wherein, The cladding raw material is treated before cladding by the following method: The nickel powder, aluminum powder, titanium powder and copper powder are mixed and dried, and are ready for use.

7. The method of claim 6, wherein, The drying temperature is 120°C, and the drying time is 2-3 h.

8. The method of claim 5, wherein, The pretreatment of the aluminum alloy substrate is carried out by the following method: the surface of the aluminum alloy substrate is polished and cleaned, is ultrasonically cleaned, and is dried and ready for use.

9. The method of claim 5, wherein, The laser beam forms a spot width of 20 mm on the surface of the aluminum alloy substrate, and the angle between the cladding head and the aluminum alloy substrate is 86-89°.

10. The method of claim 5, wherein, 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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