Preparation method of sliding bearing composite coating and sliding bearing composite coating

Abstract

The embodiment of the present disclosure provides a method for preparing a sliding bearing composite coating and a sliding bearing composite coating, which relates to the field of surface engineering technology. The method comprises: drying a nickel-based base layer alloy powder and a copper-based alloy surface layer powder; aligning a cladding head with a to-be-clad area of ​​the sliding bearing, and based on a first process parameter, uniformly feeding a nickel-based base layer alloy powder to the surface of the sliding bearing aligned with the cladding head through a scraper-type pressure powder feeder, melting the nickel-based base layer alloy powder into droplets to form a micro-molten pool with the surface of the sliding bearing, and continuously cladding to form a nickel-based base layer; after the sliding bearing with the nickel-based base layer clad on the surface is cooled, the nickel-based base layer is polished to be smooth, and based on a second process parameter, uniformly feeding a copper-based alloy surface layer powder to the surface of the nickel-based base layer through a scraper-type pressure powder feeder, and continuously cladding the surface of the nickel-based base layer to form a copper-based alloy surface layer, so as to obtain a sliding bearing with a cladding composite coating. The present disclosure can improve quality.

Description

Technical Field

[0001] The disclosed embodiments relate to the field of surface engineering technology, and in particular, to a method for preparing a sliding bearing composite coating and a sliding bearing composite coating. Background Art

[0002] Sliding bearings are mainly used in planetary gears in wind turbine gearboxes, high, medium and low speed rolling mills, etc. The use of ultra-high speed laser cladding technology to prepare anti-friction and wear-resistant coatings on the surface of sliding bearings can effectively solve the problem of bearing wear.

[0003] In the related technology, a high-speed laser cladding method is used to prepare a tin bronze cladding layer on an alloy steel substrate. The results show that the tin bronze forms a metallurgical bond with the substrate, but there are a large number of pores at the interface and middle of the coating, and the structure is unevenly distributed, which directly affects the performance of the coating. Summary of the invention

[0004] The purpose of the present disclosure is to provide a method for preparing a sliding bearing composite coating and a sliding bearing composite coating, thereby overcoming the problem of poor performance of the sliding bearing composite coating caused by the limitations and defects of the relevant technology at least to a certain extent.

[0005] According to one aspect of the present disclosure, a method for preparing a composite coating of a sliding bearing is provided, wherein the composite coating comprises a nickel-based base layer and a copper-based alloy surface layer, and the method comprises: drying a nickel-based base layer alloy powder and a copper-based alloy surface layer powder, and placing the powders into a scraper-type pressure powder feeder; aligning a cladding head with a to-be-clad area of ​​the sliding bearing, and based on a first process parameter, uniformly feeding the nickel-based base layer alloy powder to the surface of the sliding bearing aligned with the cladding head through the scraper-type pressure powder feeder, melting the nickel-based base layer alloy powder into droplets to form a micro-molten pool with the surface of the sliding bearing, and continuously cladding to form a nickel-based base layer; after the sliding bearing with the nickel-based base layer clad on the surface is cooled, polishing the nickel-based base layer to be smooth, and based on a second process parameter, uniformly feeding the copper-based alloy surface layer powder to the surface of the nickel-based base layer through the scraper-type pressure powder feeder, and continuously cladding on the surface of the nickel-based base layer to form a copper-based alloy surface layer, so as to obtain a sliding bearing with a cladding composite coating.

[0006] In an exemplary embodiment of the present disclosure, the cladding head is a coaxial annular cladding head, the spot diameter of the cladding head is 1-4 mm, and the distance from the cladding head to the area to be clad is 10-20 mm.

[0007] In an exemplary embodiment of the present disclosure, the first process parameters include: laser power 1000~3500W, line speed 0.6~2.2 m / min, powder feeding amount 5~30 g / min, single-channel lateral displacement 0.5~1.5 mm, carrier gas flow rate 0.5~1.8 L / min, and shielding gas flow rate 8~14 L / min; the second process parameters include: laser power 3000~5500 W, line speed 1.2~6.2 m / min, powder feeding amount 10~30 g / min, single-channel lateral displacement 1~1.5 mm, carrier gas flow rate 0.5~1.5 L / min, shielding gas flow rate 6~18 L / min, and cladding head inclination angle (30°~60°)±5°.

[0008] In an exemplary embodiment of the present disclosure, the powder particle size of the nickel-based base layer alloy powder and the copper-based alloy surface layer powder is 150-300 mesh, and the fluidity is less than 30s / 50g.

[0009] In an exemplary embodiment of the present disclosure, the thickness of the nickel-based primer layer is 0.2-0.8 mm, and the thickness of the copper-based alloy surface layer is 1.2-1.6 mm.

[0010] In an exemplary embodiment of the present disclosure, the average microhardness of the copper-based alloy surface layer in the sliding bearing composite coating is 110-180 HV 0.2 The average friction coefficient of the copper-based alloy surface layer is 0.1-0.3, and the bonding strength of the sliding bearing composite coating is 350-420 MPa.

[0011] In an exemplary embodiment of the present disclosure, the drying temperature is 90-120° C., and the drying time is 2 hours.

[0012] In an exemplary embodiment of the present disclosure, the method further comprises: sanding and polishing the copper-based alloy surface layer of the sliding bearing with the cladding composite coating to remove protrusions of the copper-based alloy surface layer.

[0013] In an exemplary embodiment of the present disclosure, the nickel-based base layer is one or more of nickel-chromium alloy, nickel-copper alloy, nickel-aluminum alloy and nickel-cobalt alloy; the copper-based alloy surface layer is one or more of tin bronze, aluminum bronze, beryllium bronze and lead bronze.

[0014] According to one aspect of the present disclosure, a sliding bearing composite coating is provided, wherein the sliding bearing composite coating comprises a nickel-based base layer and a copper-based alloy surface layer; the sliding bearing composite coating is prepared according to any one of the above-mentioned methods for preparing the sliding bearing composite coating.

[0015] In the technical solution provided in the embodiment of the present disclosure, on the one hand, the composite coating is composed of a nickel-based primer layer and a copper-based alloy surface layer, and the composite coating is formed on the surface of the sliding bearing by rapid heating and rapid cooling using ultra-high-speed laser cladding technology. Through the gradient transition of the primer layer, the hardness difference between the cladding layers is ensured to be moderate, the coating defects caused by the large hardness difference are avoided, and the strong bonding between the interfaces is ensured. On the other hand, the heat input is stable, the splash is small, and the dilution rate is low during the preparation of the sliding bearing composite coating. When preparing the copper-based alloy surface layer, the gas in the molten pool can be overflowed by adjusting the second process parameter, reducing the formation of pores during the metal solidification process, and by preparing the nickel-based primer layer, the problem of high porosity and low bonding strength caused by only cladding the copper-based alloy surface layer is solved, the quality of the copper-based alloy surface layer is improved, and then the quality of the coating is improved. On the other hand, the process of ultra-high-speed laser cladding technology is adopted to achieve the purpose of surface modification of the sliding bearing, and the formed composite coating has a low friction coefficient, high wear resistance, and uniform tissue distribution, which improves the performance of the composite coating. In addition, it can adapt to the complex situation of on-site construction, and the later maintenance cost is low, which improves the comprehensive performance.

[0016] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0018] Figure 1 A flow chart schematically illustrates a method for preparing a composite coating for a sliding bearing in an embodiment of the present disclosure.

[0019] Figure 2 Schematic diagram showing a metallographic image of the preparation of only the tin bronze coating.

[0020] Figure 3 Schematic diagram of the cross-sectional morphology of the sliding bearing composite coating prepared according to Example 1.

[0021] Figure 4 Schematic diagram of the interface between the copper-based alloy surface layer and the nickel-based primer layer in the sliding bearing composite coating prepared according to Example 1.

[0022] Figure 5 Schematic diagram of the interface between the nickel-based primer layer and the base layer in the sliding bearing composite coating prepared according to Example 1.

[0023] Figure 6 Schematic diagram of the microhardness of the friction-reducing and wear-resistant composite coating prepared according to Examples 1 to 4, from the copper-based alloy surface layer-nickel-based primer layer-substrate.

[0024] Figure 7 Schematic diagram of the average friction coefficient of the copper-based alloy surface layer and the average friction coefficient of the substrate in the friction-reducing and wear-resistant composite coating prepared according to Examples 1 to 4. DETAILED DESCRIPTION

[0025] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0026] The terms "a", "an", "the" and "said" used in this specification are used to indicate the presence of one or more elements / components, etc.; the terms "including" and "having" are used to express an open-ended inclusion and mean that there may be additional elements / components, etc. in addition to the listed elements / components, etc.; the terms "first" and "second" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0027] Sliding bearings have the advantages of small radial size, strong load-bearing capacity and low cost, which can significantly improve the torque density of wind power gearboxes and reduce the unit torque cost. They are mainly used in planetary gears, high, medium and low speed rolling mills in wind power gearboxes. However, due to excessive thrust or radial force, sliding bearings will have high temperature and small oil film thickness, which can easily cause serious wear and even ablation of the bearing shell.

[0028] At present, sliding bearings are usually cast by copper alloy as a whole or by centrifugal casting. The centrifugal casting injects the copper alloy into a high-speed rotating mold, causing the molten metal to perform centrifugal motion to cast a layer of copper alloy on the substrate. This method has poor bonding strength of the copper alloy and coarse grains in the casting process, which cannot meet the wear resistance and corrosion resistance requirements of the sliding bearing. The above two methods have problems such as large amount of copper alloy, large processing allowance and high manufacturing cost.

[0029] Ultra-high-speed laser cladding is a surface modification technology that combines rapid heating and rapid cooling. The powder melts when it intersects with the laser in flight space, and then forms a micro-molten pool with the surface of the substrate. It has the advantages of low dilution rate, high bonding strength, and low surface roughness. The application of ultra-high-speed laser cladding technology to prepare anti-friction and wear-resistant coatings on the surface of sliding bearings can effectively solve the problem of bearing wear.

[0030] In some embodiments, a high-speed laser cladding method can be used to prepare a CuSn12Ni2 tin bronze cladding layer on a 42CrMo alloy steel substrate. The results show that the tin bronze forms a metallurgical bond with the substrate, but there are a large number of pores at the interface and middle of the coating, and the uneven distribution of the structure directly affects the tribological properties of the coating.

[0031] In order to solve the above technical problems, the present disclosure provides a method for preparing a sliding bearing composite coating, which is used to prepare a composite coating applied to the surface of a sliding bearing. Figure 1 As shown in , it mainly includes the following steps:

[0032] In step S110, the nickel-based base alloy powder and the copper-based alloy surface layer powder are dried and placed in a scraper-type pressure powder feeder;

[0033] In step S120, the cladding head is aligned with the to-be-clad area of ​​the sliding bearing, and based on the first process parameter, the nickel-based base layer alloy powder is evenly fed to the surface of the sliding bearing aligned with the cladding head through the scraper-type pressure powder feeder, the nickel-based base layer alloy powder is melted into droplets to form a micro-molten pool with the surface of the sliding bearing, and continuous cladding is performed to form a nickel-based base layer;

[0034] In step S130, after the sliding bearing with the nickel-based base layer clad on the surface is cooled, the nickel-based base layer is polished to be smooth, and based on the second process parameter, the copper-based alloy surface layer powder is evenly fed to the surface of the nickel-based base layer through the scraper-type pressure powder feeder, and the copper-based alloy surface layer is continuously clad on the surface of the nickel-based base layer to form a copper-based alloy surface layer, so as to obtain a sliding bearing with a clad composite coating.

[0035] Next, the preparation method of the sliding bearing composite coating in the embodiment of the present disclosure is described in detail.

[0036] In step S110, the nickel-based base alloy powder and the copper-based alloy surface layer powder are dried and placed in a scraper-type pressure powder feeder.

[0037] In the disclosed embodiment, the sliding bearing composite coating may be made by mixing a nickel-based primer layer and a copper-based alloy surface layer.

[0038] First, the surface of the sliding bearing may be pretreated, and the pretreatment may include one or more of removing rust, removing oil stains, removing oxide layers, and cleaning. For example, the surface of the sliding bearing is turned to remove rust, oil stains, oxide layers, etc., and the surface is cleaned with a cleaning agent to obtain a sliding bearing workpiece before cladding, and the workpiece is fixed to a workbench.

[0039] Furthermore, the nickel-based base alloy powder and the copper-based alloy surface layer powder can be placed in a vacuum drying oven for drying, and then placed in a scraper-type pressure powder feeder after drying. The drying temperature is 90-120°C, and the drying time can be 2 hours, which can also be determined according to actual needs. The scraper-type pressure powder feeder is used to realize powder transmission, for example, the powder can be transmitted to the area to be clad on the surface of the sliding bearing or to the surface of the nickel-based base layer.

[0040] The particle size of the nickel-based base alloy powder and the copper-based alloy surface layer powder in the scraper pressure powder feeder is 150-300 mesh, and the fluidity is less than 30s / 50g. Alloy powders within this particle size range are conducive to complete melting of the powder to reduce the porosity of the coating.

[0041] In step S120, the cladding head is aligned with the area to be clad of the sliding bearing, and based on the first process parameters, the nickel-based base layer alloy powder is evenly fed to the surface of the sliding bearing aligned with the cladding head through the scraper pressure powder feeder, the nickel-based base layer alloy powder is melted into droplets to form a micro-molten pool with the surface of the sliding bearing, and continuous cladding is performed to form a nickel-based base layer.

[0042] In the disclosed embodiment, the cladding head may be a coaxial annular cladding head, the spot diameter of the coaxial annular cladding head is 1 to 4 mm, and the distance from the cladding head to the area to be clad of the sliding bearing is 10 to 20 mm. The area to be clad may be any suitable position on the surface of the sliding bearing. The first process parameter refers to the process parameter for forming a nickel-based base layer by ultra-high-speed laser cladding, which may include one or more of laser power, line speed, powder feed rate, single-channel lateral displacement, carrier gas flow rate, and shielding gas flow rate. Exemplarily, the first process parameters may include: laser power 1000 to 3500 W, line speed 0.6 to 2.2 m / min, powder feed rate 5 to 30 g / min, single-channel lateral displacement 0.5 to 1.5 mm, carrier gas flow rate 0.5 to 1.8 L / min, and shielding gas flow rate 8 to 14 L / min.

[0043] After determining the first process parameters, based on the first process parameters, nickel-based base alloy powder can be evenly fed to the surface of the sliding bearing aligned with the cladding head through a scraper pressure powder feeder to melt the nickel-based base alloy powder into droplets and form a micro molten pool with the surface of the sliding bearing.

[0044] While determining the first process parameter, a cladding trajectory program can also be determined to determine a predetermined cladding trajectory for cladding to form a nickel-based base layer according to the cladding trajectory program. Furthermore, the nickel-based base layer alloy powder can be evenly fed into the area to be clad of the sliding bearing, and continuous cladding is performed according to the predetermined cladding trajectory to form a nickel-based base layer. Among them, the thickness of the nickel-based base layer is 0.2~0.8 mm, and a gradient hardness layer is effectively formed through the gradient transition of the base layer, thereby reducing the generation of coating defects caused by hardness differences.

[0045] In step S130, after the sliding bearing with the nickel-based base layer clad on the surface is cooled, the nickel-based base layer is polished to be smooth, and based on the second process parameter, the copper-based alloy surface layer powder is evenly fed to the surface of the nickel-based base layer through the scraper-type pressure powder feeder, and the copper-based alloy surface layer is continuously clad on the surface of the nickel-based base layer to form a copper-based alloy surface layer, so as to obtain a sliding bearing with a clad composite coating.

[0046] In the embodiment of the present disclosure, after the surface of the sliding bearing is clad with a nickel-based primer layer, the nickel-based primer layer can be polished to be smooth after the sliding bearing with the nickel-based primer layer clad on the surface is cooled, and a copper-based alloy surface layer is continuously clad on the polished surface of the nickel-based primer layer according to the re-set cladding trajectory program and the second process parameters. The re-set cladding trajectory program is used to determine the cladding trajectory for cladding to form the copper-based alloy surface layer.

[0047] The second process parameters refer to the process parameters for forming a copper-based alloy surface layer by ultra-high-speed laser cladding. The second process parameters may include one or more of laser power, line speed, powder feed rate, single-pass traverse, carrier gas flow rate, shielding gas flow rate, and cladding head inclination angle. Exemplarily, the second process parameters may include: laser power 3000~5500W, line speed 1.2~6.2 m / min, powder feed rate 10~30 g / min, single-pass traverse 1~1.5 mm, carrier gas flow rate 0.5~1.5 L / min, shielding gas flow rate 6~18 L / min, cladding head inclination angle (30°~60°)±5°.

[0048] At the same time, the cladding trajectory program can be set again to determine the predetermined cladding trajectory for cladding to form the copper-based alloy surface layer. Further, continuous cladding can be performed according to the predetermined cladding trajectory to form the copper-based alloy surface layer. The thickness of the copper-based alloy surface layer is 1.2-1.6 mm.

[0049] After the nickel-based base layer and the copper-based alloy surface layer are generated, a sliding bearing composite coating can be generated. The sliding bearing composite coating can be a sliding bearing friction-reducing and wear-resistant composite coating. The average microhardness of the copper-based alloy surface layer is 110-180 HV 0.2, the average friction coefficient of the copper-based alloy surface layer is 0.1~0.3, and the bonding strength of the sliding bearing composite coating is 350~420 MPa.

[0050] After the sliding bearing composite coating is formed, the copper-based alloy surface layer in the sliding bearing composite coating can be post-processed. For example, the sliding bearing with the ultra-high-speed laser cladding anti-friction and wear-resistant composite coating is placed in a sand grinder, and the sliding bearing composite coating is sanded and polished to remove the fine protrusions of the copper-based alloy surface layer, thereby obtaining a finished sliding bearing with the ultra-high-speed laser cladding anti-friction and wear-resistant composite coating on the surface.

[0051] It should be noted that the quality of the copper-based alloy surface layer formed by cladding with the second process parameters is closely related to the material properties and process parameters. Mismatched process parameters may cause cracks, holes, oxidation and burning, high roughness, high dilution rate and other problems in the cladding layer.

[0052] In the disclosed embodiment, if the laser power exceeds the above-set range, the power is too small, which will lead to incomplete melting of the powder, pitting, and insufficient bonding force; if the laser power is too large, heat will accumulate, the dilution rate will increase, and the substrate will deform. If the line speed is lower than the above-set minimum value of 1.2 m / min, the dilution rate is low, and metallurgical bonding cannot be formed, resulting in shedding; if the line speed is higher than the above-set maximum value of 6.2 m / min, the gas is not easy to overflow and form pores. If the powder feeding amount exceeds the above-set range, after the powder flow meets the laser, the larger the powder feeding amount, the more laser energy is absorbed; when the powder amount is too large, it will lead to insufficient laser energy, and problems such as incomplete melting of the coating and pitting after grinding and polishing will occur, and the coating will also fall off; when the powder amount is too small, the thickness of the formed cladding is not enough, and the laser beam is easy to dry burn the substrate. Single-pass lateral displacement refers to the distance that the laser beam is offset in each pass. If the lateral displacement is too large, a continuous cladding layer cannot be formed, and the lower the surface roughness of the cladding layer, the more uniformity is difficult to ensure; if the lateral displacement is too small, the powder will accumulate, the thickness of the cladding layer will be large, and the pores will not overflow easily.

[0053] On this basis, when the copper-based alloy surface layer is continuously clad on the surface of the nickel-based base layer, the protective gas can be an inert gas. The inert gas protects the molten pool, which can reduce oxidation and reduce pores. Furthermore, the cladding head inclination angle in the second process parameter can be adjusted to (30°~60°)±5°, so that the pores float on the surface during the solidification of the molten metal copper-based alloy surface layer formed by the laser beam, thereby achieving gas overflow in the molten pool and reducing the formation of pores during the metal solidification process.

[0054] The composite coating in the disclosed embodiment is composed of a nickel-based base layer and a copper-based alloy surface layer, and is formed on the surface of the sliding bearing by ultra-high-speed laser cladding technology through rapid heating and rapid cooling. The gradient transition of the base layer ensures that the hardness difference between the cladding layers is moderate, avoids the occurrence of coating defects due to large hardness differences, and ensures a strong bond between interfaces.

[0055] On this basis, the preparation method of the sliding bearing composite coating disclosed in the present invention can be specifically described in combination with the embodiments.

[0056] In some embodiments, a tin bronze coating can be directly prepared on the surface of a sliding bearing, specifically comprising the following steps:

[0057] Step 1: Turn the surface of the sliding bearing to remove rust, oil stains and oxide layer, and clean the surface with a cleaning agent to obtain the workpiece before cladding, and fix it on the workbench;

[0058] Step 2: Dry the tin bronze powder in a vacuum drying oven (110°C, 2 hours) and place it in a scraper-type pressure powder feeder;

[0059] Step 3: Prepare tin bronze coating by ultra-high-speed laser cladding: Align the coaxial annular cladding head with the area to be clad of the sliding bearing, set the cladding trajectory program and process parameters, and use a scraper-type pressure powder feeder to evenly feed tin bronze alloy powder to the surface of the sliding bearing that the cladding head is aimed at. The high-energy-density laser beam melts the alloy powder into molten droplets to form a micro-molten pool on the surface of the sliding bearing workpiece, and continuously clads along a predetermined trajectory to form a tin bronze coating.

[0060] Among them, the spot diameter of the coaxial annular cladding head for ultra-high-speed laser cladding to prepare tin bronze coating is 3mm, and the distance from the coaxial annular cladding head to the area to be clad is 10mm. Its process parameters may include: laser power 1500W, line speed 0.8m / min, powder feed rate 10g / min, single-channel traverse 1mm, carrier gas flow rate 1.0L / min, and shielding gas flow rate 8L / min.

[0061] Figure 2 The metallographic image of the tin bronze coating alone is schematically shown in FIG. Figure 2 It can be seen that the porosity of the tin bronze coating is high.

[0062] In order to solve the above technical problems, an embodiment of the present disclosure provides a method for preparing a composite coating of a sliding bearing based on an ultra-high-speed laser cladding method, which is used to prepare a composite coating on the surface of a sliding bearing.

[0063] The preparation method of the sliding bearing composite coating is described in detail below in conjunction with the embodiments.

[0064] It should be noted that during the preparation process of the entire sliding bearing composite coating, the drying temperature and drying time of the nickel-based base alloy powder and the copper-based alloy surface layer powder in the vacuum drying oven, the first process parameter, the second process parameter, the spot diameter of the cladding head, and the distance from the cladding head to the area to be clad can be adjusted. Among them, for the first process parameter, one or more of them can be adjusted; for the second process parameter, one or more of them can also be adjusted.

[0065] Example 1

[0066] In this embodiment, nickel-chromium alloy is selected as the nickel-based base layer, and tin bronze is selected as the copper-based alloy surface layer.

[0067] The preparation method of the sliding bearing composite coating specifically comprises the following steps:

[0068] Step 1: Turn the surface of the sliding bearing to remove rust, oil stains and oxide layer, and clean the surface with a cleaning agent to obtain the sliding bearing before cladding, and fix it on the workbench.

[0069] Step 2: Dry the nickel-chromium alloy powder and the tin-bronze powder in a vacuum drying oven and place them in a scraper-type pressure powder feeder at a drying temperature of 90° C. for 2 hours.

[0070] Step 3: Prepare nickel-chromium base layer by ultra-high-speed laser cladding: Align the coaxial annular cladding head with the area to be clad of the sliding bearing, set the cladding trajectory program and the first process parameters, and evenly feed the nickel-chromium base layer alloy powder to the surface of the sliding bearing aimed at by the scraper-type pressure powder feeder. The high-energy-density laser beam melts the alloy powder into molten droplets to form a micro-molten pool on the surface of the sliding bearing workpiece, and continuously clads to form a nickel-chromium base layer according to the cladding trajectory determined by the cladding trajectory program.

[0071] Step 4: Prepare a tin bronze surface layer by ultra-high-speed laser cladding: After the sliding bearing with the nickel-chromium base coating clad on the surface is cooled, the nickel-chromium base coating is polished to be smooth, the cladding trajectory program and the second process parameters are set again, and continuous cladding is performed on the surface of the nickel-chromium base coating according to the predetermined trajectory corresponding to the re-set cladding trajectory program to form a tin bronze surface layer.

[0072] Among them, the spot diameter of the coaxial annular cladding head used to prepare the nickel-chromium base layer and the tin-bronze surface layer by ultra-high-speed laser cladding is 3 mm, and the distance from the coaxial annular cladding head to the area to be clad is 10 mm. The first process parameters for preparing the nickel-chromium base layer include: laser power 1500 W, line speed 0.8 m / min, powder feed 10 g / min, single-pass traverse 1 mm, carrier gas flow 1.0 L / min, and shielding gas flow 8 L / min.

[0073] According to the preparation method described above, the second process parameters for preparing the tin bronze surface layer include: laser power 3500 W, line speed 2 m / min, powder feeding amount 10 g / min, single-pass lateral displacement 1 mm, carrier gas flow rate 0.5 L / min, protective gas flow rate 10 L / min, and cladding head inclination angle 30°.

[0074] Figure 3 Schematically shows a schematic diagram of the cross-sectional morphology of the sliding bearing composite coating prepared in Example 1. For example, the cross-sectional morphology of the friction-reducing and wear-resistant composite coating can be observed using a scanning electron microscope at a magnification of 60 times. Figure 3 As shown in , the composite coating prepared according to Example 1 has a dense internal structure and no obvious pores.

[0075] The interfaces between the copper-based alloy surface layer (tin-bronze surface layer) and the nickel-chromium base layer (nickel-based base layer), and the nickel-chromium base layer and the substrate were observed by SEM at a magnification of 1000 times. Figure 4 As shown in the figure, the copper-based alloy surface layer and the nickel-based base layer form a metallurgical bond, and the structure is dense. Figure 5 As shown in the figure, a metallurgical bond is formed between the nickel-based primer and the substrate, and the structure is dense.

[0076] Example 2

[0077] In this embodiment, nickel-copper alloy is selected as the nickel-based base layer, and aluminum bronze is selected as the copper-based alloy surface layer.

[0078] The preparation method of the sliding bearing composite coating specifically comprises the following steps:

[0079] Step 1: Turn the surface of the sliding bearing to remove rust, oil stains and oxide layer, and clean the surface with a cleaning agent to obtain the sliding bearing workpiece before cladding, and fix it on the workbench.

[0080] Step 2: Dry the nickel-copper alloy powder and the aluminum-bronze powder in a vacuum drying oven and place them in a scraper-type pressure powder feeder at a drying temperature of 100° C. for 2 hours.

[0081] Step 3: Prepare nickel-copper base layer by ultra-high-speed laser cladding: Align the coaxial annular cladding head with the area to be clad of the sliding bearing, set the cladding trajectory program and the first process parameters, and evenly feed the nickel-copper base layer alloy powder to the surface of the sliding bearing aligned with the cladding head by a scraper-type pressure powder feeder. The high-energy-density laser beam melts the alloy powder into molten droplets to form a micro-molten pool with the surface of the sliding bearing workpiece, and continuously clads to form a nickel-copper base layer according to a predetermined trajectory determined by the cladding trajectory program.

[0082] Among them, the spot diameter of the coaxial annular cladding head for ultra-high-speed laser cladding to prepare nickel-copper base layer and aluminum-bronze surface layer is 2.5 mm, and the distance from the coaxial annular cladding head to the area to be clad is 18 mm. The first process parameters for preparing nickel-copper base layer include: laser power 2300W, line speed 1.2 m / min, powder feed 20 g / min, single-pass traverse 1.5 mm, carrier gas flow 1.0 L / min, and shielding gas flow 14 L / min.

[0083] Step 4: Prepare aluminum bronze surface layer by ultra-high-speed laser cladding: After the sliding bearing with nickel-copper primer coating clad on the surface is cooled, the nickel-copper primer layer is polished to be smooth, the cladding trajectory program and the second process parameters are set again, and the aluminum bronze surface layer is continuously clad on the surface of the nickel-copper primer layer according to the predetermined trajectory determined by the re-set cladding trajectory program.

[0084] The second process parameters for preparing the aluminum bronze surface layer include: laser power 5000 W, line speed 4.2 m / min, powder feed rate 30 g / min, single-pass traverse 1.5 mm, carrier gas flow rate 1.5 L / min, shielding gas flow rate 18 L / min, and cladding head inclination angle 60°.

[0085] Example 3

[0086] In this embodiment, nickel-aluminum alloy is selected as the nickel-based base layer, and beryllium bronze is selected as the copper-based alloy surface layer.

[0087] The specific preparation method of the sliding bearing composite coating comprises the following steps:

[0088] Step 1: Turn the surface of the sliding bearing to remove rust, oil stains and oxide layer, and clean the surface with a cleaning agent to obtain the sliding bearing before cladding, and fix it on the workbench.

[0089] Step 2: Dry the nickel-aluminum base layer powder and the beryllium bronze surface layer powder in a vacuum drying oven and place them in a scraper-type pressure powder feeder; wherein the drying temperature is 120° C. and the drying time is 2 hours.

[0090] Step 3: Prepare nickel-aluminum base layer by ultra-high-speed laser cladding: Align the coaxial annular cladding head with the area to be clad of the sliding bearing, set the cladding trajectory program and the first process parameters, and use a scraper-type pressure powder feeder to evenly feed the nickel-aluminum base layer alloy powder to the surface of the sliding bearing that the cladding head is aimed at. The high-energy-density laser beam melts the alloy powder into molten droplets to form a micro-molten pool with the surface of the sliding bearing, and continuously clads to form a nickel-aluminum base layer according to a predetermined trajectory determined by the cladding trajectory program.

[0091] Among them, the spot diameter of the coaxial annular cladding head used to prepare the nickel-aluminum base layer and the beryllium bronze surface layer by ultra-high-speed laser cladding is 1 mm, and the distance from the coaxial annular cladding head to the area to be clad is 15 mm. The first process parameters for preparing the nickel-aluminum base layer include: laser power 2000 W, linear speed 1 m / min, powder feed rate 10 g / min, single-pass traverse 1.2 mm, carrier gas flow rate 0.8 L / min, and shielding gas flow rate 9 L / min.

[0092] Step 4: Prepare aluminum bronze surface layer by ultra-high-speed laser cladding: After the sliding bearing with nickel-aluminum primer coating clad on the surface is cooled, the nickel-aluminum primer layer is polished to be smooth, the cladding trajectory program and the second process parameters are set again, and the beryllium bronze surface layer is continuously clad on the surface of the nickel-aluminum primer layer according to the predetermined trajectory determined by the re-set cladding trajectory program.

[0093] The second process parameters for preparing the beryllium bronze surface layer include: laser power 4500 W, line speed 3 m / min, powder feed rate 20 g / min, single-pass traverse 1.3 mm, carrier gas flow rate 1 L / min, shielding gas flow rate 12 L / min, and cladding head inclination angle 45°.

[0094] Example 4

[0095] In this embodiment, nickel-cobalt alloy is selected as the nickel-based base layer, and lead bronze is selected as the copper-based alloy surface layer.

[0096] The specific preparation method of the sliding bearing composite coating comprises the following steps:

[0097] Step 1: Turn the surface of the sliding bearing to remove rust, oil stains and oxide layer, and clean the surface with a cleaning agent to obtain the sliding bearing before cladding, and fix it on the workbench.

[0098] Step 2: Dry the nickel-cobalt base layer powder and the lead-bronze surface layer powder in a vacuum drying oven and place them in a scraper-type pressure powder feeder, wherein the drying temperature is 110° C. and the drying time is 2 hours.

[0099] Step 3: Prepare nickel-cobalt base layer by ultra-high-speed laser cladding: Align the coaxial annular cladding head with the area to be clad of the sliding bearing, set the cladding trajectory program and the first process parameters, and use a scraper-type pressure powder feeder to evenly feed the nickel-cobalt base layer alloy powder to the surface of the sliding bearing at which the cladding head is aimed. The high-energy-density laser beam melts the alloy powder into molten droplets to form a micro-molten pool with the surface of the sliding bearing, and continuously clads to form a nickel-cobalt base layer according to a predetermined trajectory determined by the cladding trajectory program.

[0100] Among them, the spot diameter of the coaxial annular cladding head for preparing the nickel-cobalt base layer and the lead-bronze surface layer by ultra-high-speed laser cladding is 4 mm, and the distance from the coaxial annular cladding head to the area to be clad is 20 mm. The first process parameters for preparing the nickel-cobalt base layer include: laser power 1000 W, line speed 0.6 m / min, powder feed 5 g / min, single-pass traverse 1.5 mm, carrier gas flow 0.5 L / min, and shielding gas flow 8 L / min.

[0101] Step 4: Prepare aluminum bronze surface layer by ultra-high-speed laser cladding: After the sliding bearing with nickel-cobalt primer coating clad on the surface is cooled, the nickel-cobalt primer layer is polished to be smooth, the cladding trajectory program and the second process parameters are set again, and the lead bronze surface layer is formed by continuous cladding on the surface of the nickel-cobalt primer layer according to the predetermined trajectory determined by the re-set cladding trajectory program.

[0102] The second process parameters for preparing the lead bronze surface layer include: laser power 5500 W, line speed 6.2 m / min, powder feed rate 30 g / min, single-pass traverse 1.3 mm, carrier gas flow rate 1.8 L / min, shielding gas flow rate 14 L / min, and cladding head inclination angle 50°.

[0103] Figure 6 The microhardness of the friction-reducing and wear-resistant composite coating prepared in Examples 1 to 4 from the copper-based alloy surface layer-nickel-based primer layer-substrate is shown in FIG. 1 , wherein the substrate refers to a sliding bearing. Figure 6 It can be seen that the average microhardness of the copper-based alloy surface layer is 151.1 HV 0.2 、149.4 HV 0.2 、154.1 HV 0.2 and 164.2 HV 0.2 , the bonding strengths of the composite coatings for sliding bearings are 384.2 MPa, 368.2 MPa, 396.5 MPa and 358.6 MPa, respectively.

[0104] refer to Figure 7 As shown in , in the friction-reducing and wear-resistant composite coatings prepared according to Examples 1 to 4, the average friction coefficients of the copper-based alloy surface layers are 0.127, 0.285, 0.167 and 0.214, respectively. The average friction coefficient of the substrate is 0.536.

[0105] The anti-friction and wear-resistant composite coating of the sliding bearing in the embodiment of the present disclosure is formed on the surface of the sliding bearing by rapid heating and rapid cooling using ultra-high-speed laser cladding technology. The gradient transition of the base layer ensures that the hardness difference between the cladding layers is moderate, avoids the occurrence of coating defects due to large hardness differences, and ensures a strong bond between interfaces. During the preparation process, the heat input is stable, the splash is small, and the dilution rate is low. When preparing the copper-based alloy surface layer, the gas in the molten pool can be overflowed by adjusting the inclination angle of the cladding head in the second process parameter. At the same time, by preparing a nickel-based base layer, the formation of pores during metal solidification is reduced. The preparation process using ultra-high-speed laser cladding technology can adapt to the complex conditions of on-site construction, and has low later maintenance costs, improves comprehensive performance, and increases the scope of application and application prospects.

[0106] In an embodiment of the present disclosure, a sliding bearing composite coating is also provided. The sliding bearing composite coating includes a nickel-based base layer and a copper-based alloy surface layer. The sliding bearing composite coating can be prepared according to the method of steps S110 to S130.

[0107] In the disclosed embodiment, the anti-friction and wear-resistant composite coating of the sliding bearing is formed on the surface of the sliding bearing by ultra-high-speed laser cladding technology through rapid heating and rapid cooling. By making a gradient transition of the bottom layer, it is ensured that the hardness difference between the cladding layers is moderate, and the coating defects caused by the large hardness difference are avoided, and the strong bonding between the interfaces is ensured.

[0108] In this exemplary embodiment, a sliding bearing is further provided. The sliding bearing is coated with the sliding bearing composite coating prepared by the above steps S110 to S130, which is not particularly limited in the embodiment of the present disclosure.

[0109] In addition, the above-mentioned figures are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present disclosure, and are not intended to be limiting. It is easy to understand that the processes shown in the above-mentioned figures do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these processes can be performed synchronously or asynchronously, for example, in multiple modules.

[0110] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

[0111] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for preparing a sliding bearing composite coating, characterized in that: The composite coating comprises a nickel-based primer layer and a copper-based alloy surface layer, and the method comprises: The nickel-based base alloy powder and the copper-based alloy surface layer powder are dried and placed into a scraper-type pressure powder feeder; The cladding head is aligned with the area to be clad of the sliding bearing. Based on the first process parameter, the nickel-based base layer alloy powder is evenly fed to the surface of the sliding bearing to which the cladding head is aligned by the scraper-type pressure powder feeder. The nickel-based base layer alloy powder is melted into molten droplets to form a micro-molten pool on the surface of the sliding bearing. A cladding trajectory program is determined. A predetermined cladding trajectory for cladding to form a nickel-based base layer is determined according to the cladding trajectory program. Continuous cladding is performed according to the predetermined cladding trajectory to form the nickel-based base layer. The cladding head is a coaxial annular cladding head. The spot diameter of the cladding head is 1-4 mm. The distance between the cladding head and the area to be clad is 10-20 mm. The thickness of the nickel-based base layer is 0.2-0.8 mm. After the sliding bearing with a nickel-based base layer clad on its surface is cooled, the nickel-based base layer is polished to a smooth surface, and based on a second process parameter, a copper-based alloy surface layer powder is evenly fed to the surface of the nickel-based base layer by the scraper-type pressure powder feeder, and a copper-based alloy surface layer is continuously clad on the surface of the nickel-based base layer based on a pre-set predetermined cladding trajectory, and the gas in the molten pool is allowed to overflow by adjusting the cladding head inclination angle in the second process parameter to obtain a sliding bearing with a cladding composite coating; the powder particle size of the nickel-based base layer alloy powder and the copper-based alloy surface layer powder is 150-300 mesh, and the fluidity is less than 30s / 50g; the thickness of the copper-based alloy surface layer is 1.2-1.6mm; The first process parameters include: laser power 1000~3500W, linear speed 0.6~2.2 m / min, powder feeding rate 5~30 g / min, single-pass traverse 0.5~1.5 mm, carrier gas flow rate 0.5~1.8 L / min, shielding gas flow rate 8~14 L / min; the second process parameters include: laser power 3000~5500 W, linear speed 1.2~6.2 m / min, powder feeding rate 10~30 g / min, single-pass traverse 1~1.5 mm, carrier gas flow rate 0.5~1.5 L / min, shielding gas flow rate 6~18 L / min, and cladding head inclination angle of 30°~60°; The average microhardness of the copper-based alloy surface layer is 110-180 HV 0.2 The average friction coefficient of the copper-based alloy surface layer is 0.1-0.3, and the bonding strength of the sliding bearing composite coating is 350-420 MPa.

2. The method for preparing a sliding bearing composite coating according to claim 1, characterized in that: The drying temperature is 90-120° C., and the drying time is 2 hours.

3. The method for preparing a sliding bearing composite coating according to claim 1, characterized in that: The method further comprises: The sliding bearing composite coating is sanded and polished to remove protrusions on the copper-based alloy surface layer.

4. The method for preparing a sliding bearing composite coating according to claim 1, characterized in that: The nickel-based primer layer is one or more of nickel-chromium alloy, nickel-copper alloy, nickel-aluminum alloy and nickel-cobalt alloy; the copper-based alloy surface layer is one or more of tin bronze, aluminum bronze, beryllium bronze and lead bronze.

5. A sliding bearing composite coating, characterized in that: The sliding bearing composite coating comprises a nickel-based base layer and a copper-based alloy surface layer; the sliding bearing composite coating is prepared according to the preparation method of the sliding bearing composite coating according to any one of claims 1-4.

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