A copper-based laser cladding material, powder, coating and method of manufacture

Abstract

The application belongs to the technical field of copper alloy substrate surface laser cladding technology, and particularly relates to a copper-based laser cladding material, a powder, a coating and a preparation method. The copper-based laser cladding material is composed of the following components by weight percentage: Cu 48-67%, Cr 28-47%, TiO2 3-7% and CeO2 0.4-0.8%. The application can simultaneously have good hardness, wear resistance and electrical conductivity.

Description

Technical Field

[0001] This invention belongs to the technical field of laser cladding technology for copper alloy substrates, specifically relating to a copper-based laser cladding material, powder, coating, and preparation method. Background Technology

[0002] Copper alloys, due to their excellent electrical and thermal conductivity, are widely used in electronics, electrical engineering, and mechanical manufacturing. However, with the continuous development of various industries, the performance of traditional copper alloys can no longer meet the requirements of some special working environments. Therefore, laser cladding, a material surface modification method, is needed to further improve the performance of copper alloys. Coaxial powder-fed laser cladding is a widely used technique for surface modification of metallic materials, which can effectively improve the surface properties of the metal substrate, making it suitable for special working environments.

[0003] Zhang Weiping, Ma Haibo. Research status of laser cladding on copper alloy surface. Mechanical Engineering Materials, 2009(9):4.DOI:CNKI:SUN:GXGC.0.2009-09-003. It is published that: In view of the physicochemical properties of copper alloys, the main materials used for laser cladding on copper alloy surface are nickel-based alloys, cobalt-based alloys, iron-based alloys and cermets. The first three are self-dissolving alloy powders. These materials contain silicon, boron and other elements with strong deoxidation and self-melting effects. During the laser cladding process, silicon and boron have slag-forming function. They preferentially melt with oxygen in the alloy powder and oxides on the workpiece surface to generate low-melting-point borosilicates and other substances that cover the surface of the molten pool, preventing excessive oxidation of the liquid metal, thereby improving the wettability of the melt to the base metal, reducing the inclusions and oxygen content in the cladding layer, and improving the process forming performance of the cladding layer.

[0004] Nickel-based self-fluxing alloy powder, with its good wettability, corrosion resistance, and high-temperature self-lubricating properties, is mainly suitable for parts requiring localized wear resistance, heat corrosion resistance, and fatigue resistance; cobalt-based self-fluxing alloy powder has good high-temperature performance and corrosion and wear resistance; iron-based alloy powder is suitable for parts requiring localized wear resistance and prone to deformation; ceramic powder can obtain high strength at high temperatures, has good thermal stability and high chemical stability, and is suitable for parts requiring wear resistance, corrosion resistance, high temperature resistance, and oxidation resistance.

[0005] Among the above material systems, nickel-based alloy cladding layers are the most widely used. Besides the good wear resistance, corrosion resistance, toughness, and good wetting and lubrication properties of nickel-based alloys, copper and nickel have very similar atomic radii, densities, and heats of combustion. Furthermore, both copper and nickel have face-centered cubic structures, allowing for infinite or finite miscibility in both solid and liquid states, which is beneficial for forming a good metallurgical bond between the substrate and the cladding layer. Liu et al. used a method of thermal spraying followed by laser remelting to add copper powder to nickel-based alloy powder to create a cladding material that was then clad onto the surface of pure copper. This not only increased the bonding force between the cladding layer and the substrate but also reduced the generation of defects such as cracks and porosity.

[0006] CN113388832A discloses a copper-based composite material with a high-hardness conductive surface and its laser additive manufacturing method. The method uses copper as the matrix, with Fe-based and Cr-based coatings sequentially applied to the surface of the copper matrix. It overcomes the significant difference in physical properties between copper and chromium, solves the problem of preparing a highly bonded chromium layer on the surface of copper workpieces, and gives the copper workpiece surface high-hardness conductive properties. While maintaining sufficient electrical properties, it effectively improves the wear resistance of the copper workpiece. Compared to common 304 stainless steel, the conductivity is increased by more than 5 times, reaching a maximum of 16.8% IACS, and the micro-Vickers hardness reaches 420 HV.

[0007] Electrical contact materials, such as electrical contacts, need to possess high wear resistance and a certain level of conductivity. Improving wear resistance requires doping and strengthening the Cu-based metal, which enhances electron scattering in the metal matrix and affects conductivity. Generally, a coating with an IACS of 25% or higher is ideal, along with a hardness of 200 HV or higher; higher wear resistance is always better. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a copper-based laser cladding material, powder, coating and preparation method, which can simultaneously have good hardness, wear resistance and conductivity.

[0009] This invention provides a copper-based laser cladding material composed of the following components by weight percentage: Cu 48-67%, Cr 28-47%, TiO 23-7%, and CeO 20.4-0.8%.

[0010] Preferably, the copper-based laser cladding material is composed of the following components in weight percentage: Cu 48~55%, Cr 40~47%, TiO2 4~6% and CeO2 0.4-0.8%.

[0011] As an example, the Cu, Cr, TiO2 and CeO2 are all in powder form with a particle size of 300-500 mesh.

[0012] This invention provides a copper-based laser cladding powder. The preparation method is as follows: the copper-based laser cladding material is mixed, a dispersant and a binder are added, the mixture is mixed evenly, and then granulated by spray drying. The granulated powder is sintered at 300~400℃ (heating rate of 2℃ / min) (holding time of 4h) to obtain laser cladding powder with a diameter of 50-70μm.

[0013] Preferably, the dispersant is water and the binder is polyvinyl alcohol.

[0014] In the mixture of copper-based laser cladding material, dispersant, and binder, the binder content is preferably 0.6-0.8 wt%, the dispersant content is 49.2-49.4 wt%, and the solid content is 50%. Ball milling is preferred to ensure uniform mixing.

[0015] As an example, in the spray drying method, the inlet temperature is 280~320℃, the outlet temperature is 70~90℃, and the atomizer rotation frequency is 35Hz.

[0016] This invention provides a method for preparing a copper-based laser cladding coating, wherein the copper-based laser cladding powder is sprayed onto the surface of a copper alloy substrate (preferably using a coaxial powder feeding laser cladding device with nitrogen as the carrier), and the copper-based laser cladding powder is melted and deposited onto the surface of the copper alloy substrate by laser cladding to obtain a copper-based laser cladding coating with a coating thickness of 1.5~2.8mm.

[0017] As one embodiment, the temperature of the copper alloy substrate is 300~400℃. The copper alloy substrate can be preheated using a heating laser source or an acetylene flame to reach this temperature. The copper alloy substrate is then polished with sandpaper to remove oil and oxides.

[0018] As an example, the working parameters of the laser cladding are: cladding spot diameter 5 mm, laser power 4200 ~ 5200 W, powder feeding rate 8-28 g / min, scanning speed 25~45 mm / s, overlap rate 45-85%, and cladding times 2-4 times.

[0019] This invention provides a copper-based laser cladding coating, which is obtained by the aforementioned method for preparing a copper-based laser cladding coating.

[0020] The beneficial effects of this invention are as follows: the coating uses four raw material powders—Cu powder, Cr powder, TiO2 powder, and CeO2 powder—and prepares a Cu-Cr-TiO2-CeO2 slurry using a planetary ball mill with polyvinyl alcohol (PVA) as a binder. This slurry is then spray-dried to prepare a powder preform, and finally sintered at 300℃-400℃ to remove the binder, yielding Cu-Cr-TiO2-CeO2 spherical laser cladding powder. A coaxial powder-feeding laser cladding device is used with argon, nitrogen, or helium as the carrier gas for laser cladding preparation. Cr has extremely high hardness and its solubility with Cu at room temperature is less than 0.4%, preventing the formation of a solid solution phase and minimizing its impact on the conductivity of the alloy material. This effectively improves the hardness and wear resistance of the coating material. Titanium dioxide is a high-hardness compound with a melting point of 1840℃, which can be used for laser cladding, providing excellent wear resistance and increasing the hardness of the coating material. Cerium oxide can effectively improve the fluidity of titanium dioxide in the matrix, making it easier for titanium dioxide to flow and adhere to the coating surface.

[0021] Using spray drying technology for laser cladding powder preparation can produce cladding powder with high sphericity and strong flowability, effectively avoiding clogging of the powder conveying pipe, and at the same time helping the powder to melt uniformly, forming a uniform molten pool and forming a metallurgical bond with the matrix.

[0022] This invention uses Cu, Cr, TiO2, and CeO2 powders as the raw materials for a copper alloy wear-resistant coating. The Cu powder matrix ensures good electrical conductivity of the coating and forms a good metallurgical bond with the copper alloy matrix. Cr and TiO2 powders provide the coating with high hardness and good friction and wear resistance. The coating's hardness, tested with a Vickers hardness tester, is in the range of 160-220 HV. Using a dry sliding friction and wear testing device (referring to GB / T 12444-2006), under a loading pressure of 20 N, and with a GCr15 steel ring with a surface roughness of 0.8 and an outer diameter of 40 mm as the friction pair, the average friction coefficient was measured to be 0.19-0.43, and the mass wear rate was 9-17 mg / km.

[0023] This invention employs spray drying combined with laser cladding technology, which can effectively improve powder flowability, optimize the coating melting effect, achieve fast production speed, and ensure high product quality stability, making it suitable for mass industrial manufacturing. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a spray drying equipment.

[0025] Figure 2 This is a schematic diagram of the laser cladding principle.

[0026] Figure 3The images show the macroscopic morphology of the laser-clad Cu-Cr-TiO2-CeO2 coatings in Examples 1 (left), 2 (middle), and 3 (right).

[0027] Figure 4 The image shows the microscopic cross-sectional morphology of the laser-clad Cu-Cr-TiO2-CeO2 coating in Example 1.

[0028] Figure 5 This is a microscopic cross-sectional elemental distribution diagram of the laser cladding Cu-Cr-TiO2-CeO2 coating in Example 1.

[0029] Figure 6 The image shows the X-ray diffraction pattern of the laser-clad Cu-Cr-TiO2-CeO2 coating in Example 1.

[0030] Figure 7 The Vickers hardness of the laser-clad Cu-Cr-TiO2-CeO2 coatings in Examples 1, 2, 3 and Comparative Example 1 is given.

[0031] Figure 8 The mass wear rate of the laser cladding Cu-Cr-TiO2-CeO2 coatings in Examples 1, 2, 3 and Comparative Example 1 is given. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the specific embodiments are only a detailed description of the present invention and should not be regarded as a limitation of the present invention.

[0033] The steps of this invention to prepare a Cu-Cr-TiO2-CeO2 wear-resistant coating on a copper alloy substrate by coaxial powder feeding and laser cladding are as follows:

[0034] (1) Weigh the corresponding masses of Cu powder, Cr powder, TiO2 powder and CeO2 powder using a test balance, and mix them. The powder mass ratio is 48-67% Cu powder, 28-47% Cr powder, 3-7% TiO2 powder and 0.4-0.8% CeO2 powder;

[0035] (2) Using deionized water as a dispersant, add the weighed powder and use polyvinyl alcohol (PVA) as a binder to prepare Cu-Cr-TiO2-CeO2 slurry. The binder content is 0.6-0.8 wt%, the dispersant content is 49.2-49.4 wt%, and the solid content is 50%. The slurry is mixed in a planetary ball mill at a ball-to-powder ratio of 1:1 for 4 hours.

[0036] (3) Cu-Cr-TiO2-CeO2 spherical powder material suitable for laser cladding was prepared by spray drying. The inlet temperature was 280℃~320℃, the outlet temperature was 70℃~90℃, and the atomizer rotation frequency was 35Hz. The granulated powder was sintered at 300℃-400℃ for 4 hours to remove the binder and obtain laser cladding powder.

[0037] (4) Use sandpaper to polish the surface of the copper alloy substrate to remove oil and oxides, and add the laser cladding powder into the barrel of the coaxial powder feeding laser cladding equipment;

[0038] (5) The copper alloy substrate is preheated with a heating laser source or acetylene flame to reach a temperature of 300°C. The powder in the cylinder is sprayed onto the substrate with nitrogen as the carrier gas using a coaxial powder feeding laser cladding device. The cladding laser melts the powder and coats it onto the surface of the copper alloy substrate. The parameters are: cladding spot diameter 5 mm, laser power 4200 W~5200 W, powder feeding rate 8-28 g / min, scanning speed 25 mm / s~45 mm / s, overlap rate 45%-85%, cladding times 2-4 times, and finally a wear-resistant Cu-Cr-TiO2-CeO2 coating sample with a coating thickness of 1.5 mm~2.8 mm is obtained.

[0039] Example 1

[0040] (1) Weigh the corresponding masses of Cu powder, Cr powder, TiO2 powder and CeO2 powder using a test balance, and mix them. The powder mass ratio is 64.6% Cu powder, 32% Cr powder, 3% TiO2 powder and 0.4% CeO2 powder;

[0041] (2) Using deionized water as a dispersant, add the weighed powder and use polyvinyl alcohol (PVA) as a binder to prepare Cu-Cr-TiO2-CeO2 slurry. The binder content is 0.6 wt%, the dispersant content is 49.4 wt%, and the solid content is 50%. The slurry is mixed in a planetary ball mill at a ball-to-powder ratio of 1:1 for 4 hours.

[0042] (3) Cu-Cr-TiO2-CeO2 spherical powder material suitable for laser cladding was prepared by spray drying. The inlet temperature was 280℃, the outlet temperature was 70℃, and the atomizer rotation frequency was 35Hz. The granulated powder was sintered at 300℃ for 4 hours to remove the binder and obtain laser cladding powder.

[0043] (4) Use sandpaper to polish the surface of the copper alloy substrate to remove oil and oxides, and add the laser cladding powder into the barrel of the coaxial powder feeding laser cladding equipment;

[0044] (5) The copper alloy substrate was preheated by a heating laser source and the substrate temperature was raised to 300℃. The powder in the cylinder was sprayed onto the substrate with nitrogen as the carrier gas using a coaxial powder feeding laser cladding equipment. The cladding laser melted the powder and coated it onto the surface of the copper alloy substrate. The parameters were: cladding spot diameter 5 mm, laser power 4200 W, powder feeding rate 12 g / min, scanning speed 25 mm / s, overlap rate 50%, cladding times 2 times, and finally a wear-resistant Cu-Cr-TiO2-CeO2 coated sample with a coating thickness of 1.7 mm was obtained.

[0045] (6) The performance of the obtained cladding layer was tested. The hardness was 158.3HV using a Vickers hardness tester. The friction coefficient was 0.38, the mass wear rate was 18mg / km, and the electrical conductivity was 28.2 IACS under a loading pressure of 20N using a dry sliding friction and wear test equipment (refer to GB / T 12444-2006).

[0046] Example 2

[0047] (1) Weigh the corresponding masses of Cu powder, Cr powder, TiO2 powder and CeO2 powder using a test balance, and mix them. The powder mass ratio is 49.4% Cu powder, 45% Cr powder, 5% TiO2 powder and 0.6% CeO2 powder;

[0048] (2) Using deionized water as a dispersant, add the weighed powder and use polyvinyl alcohol (PVA) as a binder to prepare Cu-Cr-TiO2-CeO2 slurry. The binder content is 0.6 wt%, the dispersant content is 49.4 wt%, and the solid content is 50%. The slurry is mixed in a planetary ball mill at a ball-to-powder ratio of 1:1 for 4 hours.

[0049] (3) Cu-Cr-TiO2-CeO2 spherical powder material suitable for laser cladding was prepared by spray drying. The inlet temperature was 300℃, the outlet temperature was 75℃, and the atomizer rotation frequency was 35Hz. The granulated powder was sintered at 350℃ for 4 hours to remove the binder and obtain laser cladding powder.

[0050] (4) Use sandpaper to polish the surface of the copper alloy substrate to remove oil and oxides, and add the laser cladding powder into the barrel of the coaxial powder feeding laser cladding equipment;

[0051] (5) The copper alloy substrate was preheated with a heating laser source and the substrate temperature was raised to 350°C. The powder in the cylinder was sprayed onto the substrate with nitrogen as the carrier gas using a coaxial powder feeding laser cladding equipment. The cladding laser melted the powder and coated it onto the surface of the copper alloy substrate. The parameters were: cladding spot diameter 5 mm, laser power 4800 W, powder feeding rate 18 g / min, scanning speed 30 mm / s, overlap rate 70%, cladding times 4 times, and finally a wear-resistant Cu-Cr-TiO2-CeO2 coated sample with a coating thickness of 2.6 mm was obtained.

[0052] (6) The performance of the obtained cladding layer was tested. The hardness was 182.2 HV using a Vickers hardness tester. The friction coefficient was 0.23, the mass wear rate was 15 mg / km, and the electrical conductivity was 27.3 IACS.

[0053] Example 3

[0054] (1) Weigh the corresponding masses of Cu powder, Cr powder, TiO2 powder and CeO2 powder using a test balance, and mix them. The powder mass ratio is 49.2% Cu powder, 45% Cr powder, 5% TiO2 powder and 0.8% CeO2 powder;

[0055] (2) Using deionized water as a dispersant, add the weighed powder and use polyvinyl alcohol (PVA) as a binder to prepare Cu-Cr-TiO2-CeO2 slurry. The binder content is 0.6 wt%, the dispersant content is 49.4 wt%, and the solid content is 50%. The slurry is mixed in a planetary ball mill at a ball-to-powder ratio of 1:1 for 4 hours.

[0056] (3) Cu-Cr-TiO2-CeO2 spherical powder material suitable for laser cladding was prepared by spray drying. The inlet temperature was 320℃, the outlet temperature was 80℃, and the atomizer rotation frequency was 35Hz. The granulated powder was sintered at 380℃ for 4 hours to remove the binder and obtain laser cladding powder.

[0057] (4) Use sandpaper to polish the surface of the copper alloy substrate to remove oil and oxides, and add the laser cladding powder into the barrel of the coaxial powder feeding laser cladding equipment;

[0058] (5) The copper alloy substrate was preheated by a heating laser source and the substrate temperature was raised to 350°C. The powder in the cylinder was sprayed onto the substrate with nitrogen as the carrier gas using a coaxial powder feeding laser cladding equipment. The cladding laser melted the powder and coated it onto the surface of the copper alloy substrate. The parameters were: cladding spot diameter 5 mm, laser power 5000 W, powder feeding rate 20 g / min, scanning speed 35 mm / s, overlap rate 80%, cladding times 4 times, and finally a wear-resistant Cu-Cr-TiO2-CeO2 coated sample with a coating thickness of 2.8 mm was obtained.

[0059] (6) The performance of the obtained cladding layer was tested. The hardness was 196.7 HV using a Vickers hardness tester. The friction coefficient was 0.21, the mass wear rate was 14 mg / km, and the electrical conductivity was 26.8 IACS.

[0060] Comparative Example 1

[0061] (1) Weigh the corresponding mass of Cu powder, Cr powder, TiO2 powder and CeO2 powder using a test balance, and mix them. The powder mass ratio is 64.6% Cu powder, 32% Cr powder, 3% TiO2 powder and 0.4% CeO2 powder. Place the mixed powder into a powder mixer and mix for 8 hours to obtain a uniform powder.

[0062] (2) Wipe the surface of the copper alloy substrate with sandpaper in the same direction to remove oil and oxides;

[0063] (3) Add the powder that has been mixed evenly by the powder mixer into the cylinder of the coaxial powder feeding laser cladding equipment, fix the copper alloy substrate that has been cleaned with sandpaper on the worktable of the coaxial powder feeding laser cladding equipment, turn on the laser cladding equipment and complete the inspection of each system before cladding.

[0064] (4) The copper alloy substrate was preheated by a heating laser source and the substrate temperature was raised to 300°C. The powder in the cylinder was sprayed onto the substrate with nitrogen as the carrier gas using a coaxial powder feeding laser cladding equipment. The cladding laser melted the powder and coated it onto the surface of the copper alloy substrate. The parameters were: cladding spot diameter 5 mm, laser power 4200 W, powder feeding rate 12 g / min, scanning speed 25 mm / s, overlap rate 50%, cladding times 2 times, and finally a wear-resistant Cu-Cr-TiO2-CeO2 coated sample with a coating thickness of 1.7 mm was obtained.

[0065] (5) The performance of the obtained cladding layer was tested. The hardness was 137.8 HV using a Vickers hardness tester. Using a dry sliding friction and wear tester (refer to GB / T 12444-2006), under a loading pressure of 20 N, a GCr15 steel ring with a surface roughness of 0.8 and an outer diameter of 40 mm was used as the friction pair. The friction coefficient was measured to be 0.37 and the mass wear rate was 19 mg / km. Due to the need for spray granulation, the laser cladding powder had poor flowability and low cladding efficiency. The powder feeding pipe was blocked multiple times during the cladding process. The electrical conductivity was 17.2 IACS.

[0066] Comparative Example 2

[0067] Compared with Example 3, Comparative Example 2 differs in the powder ratio. The ratio of Comparative Example 2 is: Cu powder 49.2%, Cr powder 45%, ZrO2 powder 5%, Y2O3 powder 0.8%, with other components the same as in Example 3. The same testing method as in Example 3 was used, and the hardness was 109.3, the mass wear rate was 34 mg / km, and the electrical conductivity was 29.3 IACS.

[0068] Comparative Example 3

[0069] The difference between Comparative Example 3 and Example 3 lies in the powder composition. Comparative Example 3 has the following composition: Cu powder 45%, Cr powder 39%, TiO2 powder 4%, CeO2 powder 0.6%, Fe 5.4%, and Ni 6%. All other components are the same as in Example 3. The same testing methods as in Example 3 were used, and the hardness was 142.4, the wear rate was 21.3 mg / km, and the conductivity was 11.2 IACS.

[0070] Comparative Example 4

[0071] Compared with Example 3, Comparative Example 4 differs in that the granulated powder was sintered at 600°C for 4 hours to obtain laser cladding powder. Everything else is the same as in Example 3. Tests were conducted using the same methods as in Example 3, and the hardness was 137.3, the mass abrasion rate was 29 mg / km, and the electrical conductivity was 22.3 IACS.

[0072] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0073] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A copper-based laser cladding powder, characterized in that, The preparation method is as follows: copper-based laser cladding material is mixed, dispersant and binder are added, the mixture is mixed evenly, and then granulated by spray drying. The granulated powder is sintered at 300~400℃ to obtain laser cladding powder. The copper-based laser cladding material is composed of the following components by weight percentage: Cu 48-55%, Cr 40-47%, TiO2 4-6%, and CeO2 0.4-0.8%. Cu, Cr, TiO2 and CeO2 are all in powder form with a particle size of 300-500 mesh.

2. The copper-based laser cladding powder as described in claim 1, characterized in that, The dispersant is water, and the binder is polyvinyl alcohol.

3. The copper-based laser cladding powder as described in claim 1, characterized in that, In the spray drying method, the inlet temperature is 280~320℃ and the outlet temperature is 70~90℃.

4. A method for preparing a copper-based laser cladding coating, characterized in that, The copper-based laser cladding powder as described in any one of claims 1-3 is sprayed onto the surface of a copper alloy substrate, and the copper-based laser cladding powder is melted and coated onto the surface of the copper alloy substrate by laser cladding to obtain a copper-based laser cladding coating.

5. The preparation method according to claim 4, characterized in that, The temperature of the copper alloy matrix is ​​300~400℃.

6. The preparation method according to claim 4, characterized in that, The working parameters of the laser cladding are as follows: cladding spot diameter 5 mm, laser power 4200 ~ 5200 W, powder feeding rate 8-28 g / min, scanning speed 25~45 mm / s, overlap rate 45-85%, and cladding times 2-4 times.

7. A copper-based laser cladding coating, characterized in that, It is obtained by the preparation method described in any one of claims 4-6.

Images