Gradient alloy coating and preparation method thereof

Abstract

The invention relates to the technical field of coating materials, in particular to a gradient alloy coating and a preparation method of the gradient alloy coating. The preparation method of the gradient alloy coating comprises the steps that a cold spraying technology is adopted for conducting first spraying on base coat powder on a sliding bearing to obtain a base coat; copper-based alloy powder is subjected to second spraying on the base layer through the cold spraying technology, and the copper-based alloy surface layer is obtained; wherein the thickness of the bottom layer is 12%-20% of the thickness of the copper-based alloy surface layer. The problems that in the prior art, holes exist in a surface coating interface of a sliding bearing, the bonding strength is poor, the coating is prone to stripping under the heavy load condition, and consequently the sliding bearing is stuck in the running process can be solved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of coating materials, and in particular to a gradient alloy coating and a method for preparing the gradient alloy coating. Background Art

[0002] Compared with traditional rolling bearings, sliding bearings have the advantages of strong load-bearing capacity, small size and simple structure. In the application of wind turbine gearboxes, they can greatly improve the load-bearing capacity of wind turbines and reduce the maintenance cost of wind turbines. Therefore, the trend of "replacing rolling bearings with sliding bearings" has gradually emerged in recent years.

[0003] However, during the service life of the sliding bearing, its working surface will be subjected to severe heavy-load friction and wear, which reduces its service life. The traditional solution is to install a copper sleeve component on the working surface of the sliding bearing, but the production process of the copper sleeve component is complicated, the precision requirements and the cost are high. With the development of surface technology, there is a great potential for preparing a self-lubricating coating on the surface of the sliding bearing to improve its service life.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The purpose of the present disclosure is to provide a gradient alloy coating and a preparation method thereof, aiming to solve the problems in the prior art of the existence of holes in the coating interface of the sliding bearing surface, poor bonding strength, and easy peeling of the coating under heavy load conditions, which leads to the jamming of the sliding bearing during operation.

[0006] Other features and advantages of the present disclosure will become apparent from the following detailed description, or may be learned in part by the practice of the present disclosure.

[0007] According to one aspect of the present disclosure, a method for preparing a gradient alloy coating is provided, wherein the gradient alloy coating comprises a base layer and a copper-based alloy surface layer, and the method comprises: using a cold spraying technique to perform a first spraying of base layer powder on a sliding bearing to obtain the base layer; using a cold spraying technique to perform a second spraying of a copper-based alloy powder on the base layer to obtain the copper-based alloy surface layer; wherein the thickness of the base layer is 12% to 20% of the thickness of the copper-based alloy surface layer.

[0008] Optionally, the base layer is an aluminum alloy or a nickel-based alloy, and the copper-based alloy is a lead-tin-copper alloy, an aluminum-iron-copper alloy, a nickel-tin-copper alloy, or a bismuth-nickel-tin-copper alloy.

[0009] Optionally, after obtaining the copper-based alloy surface layer, the method further comprises: annealing the first gradient alloy coating composed of the base layer and the copper-based alloy surface layer to obtain a second gradient alloy coating; and smoothing the surface of the second gradient alloy coating to obtain a third gradient alloy coating.

[0010] Optionally, the thickness of the first gradient alloy coating is 0.3% to 0.8% of the diameter of the sliding bearing; the thickness of the third gradient alloy coating is 0.2% to 0.9% of the diameter of the sliding bearing.

[0011] Optionally, the process parameters of the annealing treatment are: annealing temperature is 200° C. to 600° C., and annealing time is 2 h to 10 h.

[0012] Optionally, the process parameters of the first spraying are: the spraying gas is nitrogen, argon or helium, the spraying temperature is 200° C. to 850° C., the spraying distance is 10 mm to 40 mm, and the spraying pressure is 3 MPa to 6 MPa.

[0013] Optionally, the process parameters of the second spraying are: the spraying gas is nitrogen or argon, the spraying temperature is 500° C. to 950° C., the spraying distance is 20 mm to 30 mm, and the spraying pressure is 3.5 MPa to 6 MPa.

[0014] Optionally, before adopting the cold spraying process, the method further includes: drying the base layer powder and the copper-based alloy powder; the process parameters of the drying process are: drying temperature of 80° C. to 100° C., and drying time of 2 h to 4 h.

[0015] Optionally, before adopting the cold spraying process, the method also includes: sandblasting the surface of the sliding bearing substrate; the process parameters of the sandblasting are: the sandblasting grit is brown corundum, the mesh size is 20 mesh to 60 mesh, the sandblasting pressure is 0.6 MPa to 0.8 MPa, and the sandblasting distance is 50 mm to 100 mm.

[0016] According to a second aspect of the present disclosure, a gradient alloy coating is provided. The gradient alloy coating is obtained by using the preparation method of the gradient alloy coating as described above.

[0017] The exemplary embodiments of the present disclosure may have some or all of the following beneficial effects:

[0018] In the technical solutions provided in some embodiments of the present disclosure, on the one hand, the thickness of the base layer and the thickness of the copper-based alloy coating are set within a certain proportional range, which effectively improves the bonding strength of the cold-sprayed copper-based alloy coating and greatly reduces the preparation cost of the cold-sprayed copper-based alloy; on the other hand, the cold spraying technology is used to prepare the coating for wind power sliding bearings, which not only avoids the holes that appear at the interface between the laser cladding coating and the substrate, but also effectively prevents the diamond-like gradient thin coating from peeling off and causing the sliding bearing to get stuck during operation.

[0019] 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

[0020] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0021] Figure 1 A schematic diagram schematically shows a process flow diagram of a method for preparing a gradient alloy coating in an exemplary embodiment of the present disclosure;

[0022] Figure 2 A schematic diagram schematically shows the macroscopic morphology of a gradient alloy coating prepared by exemplary embodiment 1 of the present disclosure;

[0023] Figure 3 A schematic diagram schematically shows the microscopic morphology of the base layer and the copper-based alloy surface layer prepared in exemplary embodiment 1 of the present disclosure;

[0024] Figure 4 A schematic diagram schematically shows the microhardness of the gradient alloy coating prepared by exemplary embodiment 1 of the present disclosure;

[0025] Figure 5 The friction coefficient curve of the gradient alloy coating prepared according to exemplary embodiment 1 of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0026] 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 limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more comprehensive and complete and will fully convey the concept of the example embodiments to those skilled in the art.

[0027] In addition, 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 without one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the present disclosure.

[0028] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0029] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0030] Compared with traditional rolling bearings, sliding bearings have the following two advantages in the application of wind turbine gearboxes due to their strong load-bearing capacity, small size, and simple structure. First, the load-bearing capacity of wind turbines using sliding bearings can be greatly improved. Traditional rolling bearings are point contact or line contact, and their unit weight or size load-bearing capacity is limited. Sliding bearings are surface contact, so their load-bearing capacity is greatly increased. Second, wind turbines using sliding bearings have low maintenance costs. The structure of sliding bearings can be designed as a block type, which is suitable for wind turbines with higher capacity. The flexible installation structure can effectively realize the on-site installation and maintenance of bearings. Therefore, the trend of "replacing rolling with sliding" has gradually emerged in recent years.

[0031] However, during the service life of the sliding bearing, its working surface will be subjected to severe heavy-load friction and wear, which reduces its service life. The traditional solution is to install a copper sleeve component on the working surface of the sliding bearing, but the production process of the copper sleeve component is complicated, the precision requirements and the cost are high. With the development of surface technology, there is a great potential for preparing a self-lubricating coating on the surface of the sliding bearing to improve its service life.

[0032] Some solutions are provided in the prior art, such as using laser cladding technology to prepare a copper-based alloy base layer, and using a coating method to prepare a gradient self-lubricating coating on the surface layer. However, when using laser cladding technology to prepare a copper-based alloy coating, hole defects will inevitably appear on the interface, causing the coating to easily initiate cracks along the holes at the interface during service. Alternatively, physical vapor deposition technology is used to prepare a diamond-like carbon base layer, and a coating method is used to prepare a gradient self-lubricating coating on the surface layer. However, during the assessment of actual wind farms, the diamond-like gradient self-lubricating coating is relatively thin and is very easy to peel off under heavy load conditions, causing the sliding bearing to get stuck during service. Alternatively, after cold spraying is used to prepare a copper-based alloy coating, laser remelting is used for post-processing. However, laser remelting inevitably causes hole defects in the coating, reducing the quality of the coating.

[0033] Therefore, in view of the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing a gradient alloy coating to solve the problems in the prior art of the presence of holes in the coating interface on the surface of the sliding bearing, poor bonding strength, easy peeling of the coating under heavy load conditions, and resulting in the sliding bearing getting stuck during operation.

[0034] The implementation details of the technical solution of the embodiment of the present disclosure are elaborated in detail below.

[0035] Figure 1 The following is a schematic diagram of a method for preparing a gradient alloy coating in an exemplary embodiment of the present disclosure. Figure 1 As shown, the gradient alloy coating includes a base layer and a copper-based alloy surface layer, and the preparation method of the gradient alloy coating includes steps S101 and S103:

[0036] Step S101, using cold spraying technology to spray the primer powder on the sliding bearing for the first time to obtain the primer;

[0037] Step S103, using cold spraying technology to perform a second spraying of copper-based alloy powder on the base layer to obtain the copper-based alloy surface layer; wherein the thickness of the base layer is 12% to 20% of the thickness of the copper-based alloy surface layer.

[0038] In the technical solutions provided in some embodiments of the present disclosure, on the one hand, the thickness of the base layer and the thickness of the copper-based alloy coating are set within a certain proportional range, which effectively improves the bonding strength of the cold-sprayed copper-based alloy coating and greatly reduces the preparation cost of the cold-sprayed copper-based alloy; on the other hand, the cold spraying technology is used to prepare the coating for wind power sliding bearings, which not only avoids the holes that appear at the interface between the laser cladding coating and the substrate, but also effectively prevents the diamond-like gradient thin coating from peeling off and causing the sliding bearing to get stuck during operation.

[0039] Below, each step of the method for preparing the gradient alloy coating in this exemplary embodiment will be described in more detail with reference to the accompanying drawings and examples.

[0040] First, a base layer powder is first sprayed on a sliding bearing using a cold spraying technique to obtain the base layer; then, a copper-based alloy powder is secondly sprayed on the base layer using a cold spraying technique to obtain the copper-based alloy surface layer.

[0041] In one embodiment of the present disclosure, the process parameters of the first spraying are: the spraying gas is nitrogen, argon or helium, the spraying temperature is 200°C to 850°C, the spraying distance is 10mm to 40mm, and the spraying pressure is 3MPa to 6MPa.

[0042] Specifically, before spraying, the powder and the sliding bearing substrate may be pre-treated.

[0043] In one embodiment of the present disclosure, before the cold spraying process is adopted, the method further comprises: drying the primer powder and the copper-based alloy powder.

[0044] Specifically, the base layer powder and the copper-based alloy powder are placed in a tray and placed in a vacuum oven for drying. The temperature of the vacuum oven is 80° C. to 100° C., and the drying time is 2 h to 4 h.

[0045] In one embodiment of the present disclosure, before the cold spraying process is adopted, the method further comprises: performing sandblasting on the surface of the sliding bearing substrate.

[0046] Specifically, the surface of the sliding bearing is sandblasted, and the area outside the sandblasting is protected by iron sheet, and then the sand embedded in the surface is scraped off with a steel brush. The sandblasting sand is brown corundum, the mesh number is 20 mesh to 60 mesh, the sandblasting pressure is 0.6 MPa to 0.8 MPa, and the sandblasting distance is 50 mm to 100 mm.

[0047] In one embodiment of the present disclosure, a cold spraying process is adopted to sequentially prepare a base layer and a copper-based alloy surface layer on the surface of a sliding bearing by means of a high-pressure cold spraying device.

[0048] The base layer is aluminum alloy or nickel-based alloy, and the copper-based alloy is lead-tin-copper alloy, aluminum-iron-copper alloy, nickel-tin-copper alloy or bismuth-nickel-tin-copper alloy. It should be noted that the thickness of the base layer is 12% to 20% of the thickness of the copper-based alloy surface layer.

[0049] Based on the above method, an aluminum alloy or nickel-based alloy coating is used as the base layer of the copper-based alloy coating, and the thickness of the base layer and the thickness of the copper-based alloy coating are set within a certain proportional range, which effectively improves the bonding strength of the cold-sprayed copper-based alloy coating and greatly reduces the preparation cost of the cold-sprayed copper-based alloy.

[0050] In one embodiment of the present disclosure, the process parameters of the second spraying are: the spraying gas is nitrogen or argon, the spraying temperature is 500° C. to 950° C., the spraying distance is 20 mm to 30 mm, and the spraying pressure is 3.5 MPa to 6 MPa.

[0051] Based on the above method, cold spraying technology is used to prepare coatings for wind power sliding bearings, which not only avoids the appearance of holes at the interface between the laser cladding coating and the substrate, but also effectively prevents the diamond-like gradient thin coating from peeling off and causing the sliding bearing to get stuck during operation.

[0052] In one embodiment of the present disclosure, after obtaining the copper-based alloy surface layer, the method further includes: annealing the first gradient alloy coating composed of the base layer and the copper-based alloy surface layer to obtain a second gradient alloy coating; and smoothing the surface of the second gradient alloy coating to obtain a third gradient alloy coating.

[0053] In one embodiment of the present disclosure, the process parameters of the annealing treatment are: annealing temperature is 200° C. to 600° C., and annealing time is 2 h to 10 h.

[0054] After two sprayings, the initial first gradient alloy coating is obtained, and the thickness of the coating is 0.3% to 0.8% of the diameter of the sliding bearing. After annealing, the surface of the gradient alloy coating is processed flat, and the final total thickness of the coating is 0.2% to 0.9% of the diameter of the sliding bearing.

[0055] Based on the above method, the cold sprayed gradient alloy coating is annealed, which further improves the bonding strength of the coating while improving the hardness and friction and wear properties of the coating, thereby increasing the service life of the wind power sliding bearing.

[0056] Example 1

[0057] In the gradient alloy coating for sliding bearings and the preparation method thereof of the present embodiment, the gradient alloy coating is composed of two layers, and the coatings in contact with the sliding bearing substrate are: the first layer is an aluminum alloy base layer, and the second layer is a nickel-tin-copper alloy surface layer;

[0058] The specific steps include:

[0059] Step 1, powder pretreatment: placing the aluminum alloy base layer powder and the nickel-tin-copper alloy powder in a tray and placing them in a vacuum oven for drying, the oven temperature is 80° C., and the drying time is 2 h;

[0060] Step 2: Surface treatment of the substrate: sandblast the surface of the wind turbine sliding bearing, and use iron sheet to protect the area outside the sandblasting. Then use a steel brush to scrape off the gravel embedded in the surface. The sandblasting gravel is brown corundum with a mesh size of 20. The sandblasting pressure is 0.6MPa and the sandblasting distance is 50mm.

[0061] Step three, preparation of cold spray coating: Use high-pressure cold spray equipment to prepare aluminum alloy base layer and nickel-tin-copper alloy surface layer on the surface of wind power sliding bearing in sequence. When preparing the aluminum alloy base layer, the spraying gas is nitrogen, the spraying temperature is 200°C, the spraying distance is 10mm, and the spraying pressure is 3.5MPa. When preparing the nickel-tin-copper alloy surface layer, the spraying gas is nitrogen, the spraying temperature is 500°C, the spraying distance is 20mm, and the spraying pressure is 3MPa. The thickness of the prepared aluminum alloy base layer is 12% of the thickness of the nickel-tin-copper alloy surface layer, and the total thickness of the gradient alloy coating is 0.3% of the diameter of the sliding bearing;

[0062] Step 4: Post-treatment of the gradient alloy coating: annealing the cold sprayed gradient alloy coating at a temperature of 200° C. for 10 h;

[0063] Step 5: Surface processing of the gradient alloy coating: The surface of the gradient alloy coating is processed to be smooth, and the final total thickness of the coating is 0.2% of the diameter of the sliding bearing.

[0064] Figure 2 The macroscopic morphology of the gradient alloy coating prepared by the exemplary embodiment 1 of the present disclosure is schematically shown. Figure 2 As shown in the figure, the magnification is 200 times. The gradient alloy coating includes an aluminum alloy base layer and a nickel-tin-copper alloy surface layer. There are no defects such as macro cracks and holes inside the coating and at the interface.

[0065] Figure 3 The microscopic morphology diagram of the base layer and the copper-based alloy surface layer prepared in exemplary embodiment 1 of the present disclosure is schematically shown. Figure 3 for Figure 2 Schematic diagram of the morphology after further enlargement, the magnification is 2000 times, refer to Figure 3 (a) and Figure 3 (b) The base layer and the copper-based alloy surface layer are dense and free of pores.

[0066] Figure 4 The microhardness diagram of the gradient alloy coating prepared according to exemplary embodiment 1 of the present disclosure is schematically shown. Figure 4 The average microhardness of the base layer is 130HV. 0.1The average microhardness of the copper-based alloy surface layer (i.e. the outer surface of the gradient alloy coating) is 180HV 0.1 , basically meeting the usage requirements.

[0067] Figure 5 The friction coefficient curve of the gradient alloy coating prepared according to exemplary embodiment 1 of the present disclosure is schematically shown. Figure 5 It shows that the average friction coefficient of the copper-based alloy coating is 0.25, which meets the usage requirements.

[0068] Example 2

[0069] In the gradient alloy coating for sliding bearings and the preparation method thereof of the present embodiment, the gradient alloy coating is composed of two layers, and the coatings in contact with the sliding bearing substrate are: the first layer is a nickel-based alloy base layer, and the second layer is an aluminum-iron-copper alloy surface layer;

[0070] The specific steps include:

[0071] Step 1, powder pretreatment: placing the aluminum alloy base layer powder and the nickel-tin-copper alloy powder in a tray and placing them in a vacuum oven for drying, the oven temperature is 100° C., and the drying time is 4 hours;

[0072] Step 2: Surface treatment of the substrate: sandblast the surface of the wind turbine sliding bearing, and use iron sheet to protect the area outside the sandblasting. Then use a steel brush to scrape off the gravel embedded in the surface. The sandblasting gravel is brown corundum with a mesh size of 60. The sandblasting pressure is 0.8 MPa and the sandblasting distance is 100 mm.

[0073] Step three, preparation of cold spray coating: Use high-pressure cold spray equipment to prepare nickel-based alloy base layer and aluminum-iron-copper alloy surface layer on the surface of wind power sliding bearing in sequence. Wherein, when preparing the nickel-based alloy base layer, the spraying gas is helium, the spraying temperature is 850°C, the spraying distance is 40mm, and the spraying pressure is 6MPa. When preparing the aluminum-iron-copper alloy surface layer, the spraying gas is argon, the spraying temperature is 950°C, the spraying distance is 30mm, and the spraying pressure is 6MPa. The thickness of the prepared nickel-based alloy base layer is 20% of the thickness of the aluminum-iron-copper alloy surface layer, and the total thickness of the gradient alloy coating is 0.8% of the diameter of the sliding bearing;

[0074] Step 4: Post-treatment of the gradient alloy coating: annealing the cold sprayed gradient alloy coating at a temperature of 600° C. for 2 h;

[0075] Step 5: Surface processing of the gradient alloy coating: The surface of the gradient alloy coating is processed to be smooth, and the final total thickness of the coating is 0.9% of the diameter of the sliding bearing.

[0076] In this embodiment, there are no macro cracks and holes in the interior and interface of the cold sprayed gradient alloy coating, the base layer and the copper-based alloy surface layer are dense and free of pores, and the microhardness of the copper-based alloy surface layer is 190HV 0.1 The average friction coefficient is 0.21, which meets the service requirements.

[0077] Example 3

[0078] In the gradient alloy coating for sliding bearings and the preparation method thereof of the present embodiment, the gradient alloy coating is composed of two layers, and the coatings in contact with the sliding bearing substrate are: the first layer is an aluminum alloy base layer, and the second layer is a lead-tin-copper alloy surface layer;

[0079] The specific steps include:

[0080] Step 1, powder pretreatment: placing the aluminum alloy base layer powder and the lead-tin-copper alloy powder in a tray and placing them in a vacuum oven for drying, the oven temperature is 85° C., and the drying time is 2.5 h;

[0081] Step 2: Surface treatment of the substrate: sandblast the surface of the wind turbine sliding bearing, and use iron sheet to protect the area outside the sandblasting. Then use a steel brush to scrape off the gravel embedded in the surface. The sandblasting gravel is brown corundum with a mesh size of 30. The sandblasting pressure is 0.7 MPa and the sandblasting distance is 60 mm.

[0082] Step three, preparation of cold spray coating: Use high-pressure cold spray equipment to prepare aluminum alloy base layer and lead-tin-copper alloy surface layer on the surface of wind power sliding bearing in sequence. When preparing the aluminum alloy base layer, the spraying gas is argon, the spraying temperature is 300°C, the spraying distance is 20mm, and the spraying pressure is 4MPa. When preparing the lead-tin-copper alloy surface layer, the spraying gas is argon, the spraying temperature is 600°C, the spraying distance is 25mm, and the spraying pressure is 4MPa. The thickness of the prepared aluminum alloy base layer is 15% of the thickness of the lead-tin-copper alloy surface layer, and the total thickness of the gradient alloy coating is 0.5% of the diameter of the sliding bearing;

[0083] Step 4: Post-treatment of the gradient alloy coating: annealing the cold sprayed gradient alloy coating at a temperature of 400° C. for 3 h;

[0084] Step 5: Surface processing of the gradient alloy coating: The surface of the gradient alloy coating is processed to be smooth, and the final total thickness of the coating is 0.6% of the diameter of the sliding bearing.

[0085] In this embodiment, there are no macro cracks and holes in the cold sprayed gradient alloy coating and its interface, the base layer and the copper-based alloy surface layer are dense and free of pores, and the average microhardness of the copper-based alloy surface layer is 182HV 0.1 The average friction coefficient is 0.23, which meets the service requirements.

[0086] Example 4

[0087] In the gradient alloy coating for sliding bearings and the preparation method thereof of the present embodiment, the gradient alloy coating is composed of two layers, and the coatings in contact with the sliding bearing substrate are: the first layer is a nickel-based alloy base layer, and the second layer is a bismuth-nickel-tin-copper alloy surface layer;

[0088] The specific steps include:

[0089] Step 1, powder pretreatment: placing the aluminum alloy base layer powder and the lead-tin-copper alloy powder in a tray and placing them in a vacuum oven for drying, the oven temperature is 90° C., and the drying time is 3 hours;

[0090] Step 2: Surface treatment of the substrate: sandblast the surface of the wind turbine sliding bearing, and use iron sheet to protect the area outside the sandblasting. Then use a steel brush to scrape off the gravel embedded in the surface. The sandblasting gravel is brown corundum with a mesh size of 40. The sandblasting pressure is 0.75 MPa and the sandblasting distance is 70 mm.

[0091] Step three, preparation of cold spray coating: Use high-pressure cold spray equipment to prepare nickel-based alloy base layer and bismuth-nickel-tin-copper alloy surface layer on the surface of wind power sliding bearing in sequence. Wherein, when preparing the nickel-based alloy base layer, the spraying gas is nitrogen, the spraying temperature is 400°C, the spraying distance is 30mm, and the spraying pressure is 3.7MPa. When preparing the bismuth-nickel-tin-copper alloy surface layer, the spraying gas is nitrogen, the spraying temperature is 700°C, the spraying distance is 28mm, and the spraying pressure is 4.5MPa. The thickness of the prepared nickel-based alloy base layer is 18% of the thickness of the bismuth-nickel-tin-copper alloy surface layer, and the total thickness of the gradient alloy coating is 0.7% of the diameter of the sliding bearing;

[0092] Step 4: Post-treatment of the gradient alloy coating: annealing the cold sprayed gradient alloy coating at a temperature of 500° C. for 4 h;

[0093] Step 5: Surface processing of the gradient alloy coating: The surface of the gradient alloy coating is processed to be smooth, and the final total thickness of the coating is 0.8% of the diameter of the sliding bearing.

[0094] In this embodiment, there are no macro cracks and holes in the interior and interface of the cold sprayed gradient alloy coating, the base layer and the copper-based alloy surface layer are dense and free of pores, and the average microhardness of the copper-based alloy surface layer is 173HV 0.1 The average friction coefficient is 0.19, which meets the usage requirements.

[0095] Example 5

[0096] In the gradient alloy coating for sliding bearings and the preparation method thereof of the present embodiment, the gradient alloy coating is composed of two layers, and the coatings in contact with the sliding bearing substrate are: the first layer is an aluminum alloy base layer, and the second layer is a lead-tin-copper alloy surface layer;

[0097] The specific steps include:

[0098] Step 1, powder pretreatment: placing the aluminum alloy base layer powder and the lead-tin-copper alloy powder in a tray and placing them in a vacuum oven for drying, the oven temperature is 95° C., and the drying time is 3.5 hours;

[0099] Step 2: Surface treatment of the substrate: sandblast the surface of the wind turbine sliding bearing, and use iron sheet to protect the area outside the sandblasting. Then use a steel brush to scrape off the gravel embedded in the surface. The sandblasting gravel is brown corundum with a mesh size of 50. The sandblasting pressure is 0.65 MPa and the sandblasting distance is 80 mm.

[0100] Step three, preparation of cold spray coating: Use high-pressure cold spray equipment to prepare aluminum alloy base layer and lead-tin-copper alloy surface layer on the surface of wind power sliding bearing in sequence. Wherein, when preparing the aluminum alloy base layer, the spraying gas is argon, the spraying temperature is 500°C, the spraying distance is 35mm, and the spraying pressure is 4.2MPa. When preparing the lead-tin-copper alloy surface layer, the spraying gas is argon, the spraying temperature is 800°C, the spraying distance is 23mm, and the spraying pressure is 4.8MPa. The thickness of the prepared aluminum alloy base layer is 15% of the thickness of the lead-tin-copper alloy surface layer, and the total thickness of the gradient alloy coating is 0.6% of the diameter of the sliding bearing;

[0101] Step 4: Post-treatment of the gradient alloy coating: annealing the cold sprayed gradient alloy coating at a temperature of 550° C. for 6 h;

[0102] Step 5: Surface processing of the gradient alloy coating: The surface of the gradient alloy coating is processed to be smooth, and the final total thickness of the coating is 0.4% of the diameter of the sliding bearing.

[0103] In this embodiment, there are no macro cracks and holes in the cold sprayed gradient alloy coating and its interface, the base layer and the copper-based alloy surface layer are dense and free of pores, and the average microhardness of the copper-based alloy surface layer is 184HV 0.1 The average friction coefficient is 0.22, which meets the usage requirements.

[0104] Example 6

[0105] In the gradient alloy coating for sliding bearings and the preparation method thereof of the present embodiment, the gradient alloy coating is composed of two layers, and the coatings in contact with the sliding bearing substrate are: the first layer is a nickel-based alloy base layer, and the second layer is an aluminum-iron-copper alloy surface layer;

[0106] The specific steps include:

[0107] Step 1, powder pretreatment: placing the nickel-based alloy base layer powder and the aluminum-iron-copper alloy powder in a tray and placing them in a vacuum oven for drying, the oven temperature is 85° C., and the drying time is 2.8 hours;

[0108] Step 2: Surface treatment of the substrate: sandblast the surface of the wind turbine sliding bearing, and use iron sheet to protect the area outside the sandblasting. Then use a steel brush to scrape off the gravel embedded in the surface. The sandblasting gravel is brown corundum with a mesh size of 55. The sandblasting pressure is 0.68 MPa and the sandblasting distance is 90 mm.

[0109] Step three, preparation of cold spray coating: Use high-pressure cold spray equipment to prepare nickel-based alloy base layer and aluminum-iron-copper alloy surface layer on the surface of wind power sliding bearing in sequence. Wherein, when preparing the nickel-based alloy base layer, the spraying gas is nitrogen, the spraying temperature is 700°C, the spraying distance is 38mm, and the spraying pressure is 4.3MPa. When preparing the aluminum-iron-copper alloy surface layer, the spraying gas is nitrogen, the spraying temperature is 850°C, the spraying distance is 27mm, and the spraying pressure is 4.7MPa. The thickness of the prepared nickel-based alloy base layer is 17% of the thickness of the aluminum-iron-copper alloy surface layer, and the total thickness of the gradient alloy coating is 0.75% of the diameter of the sliding bearing;

[0110] Step 4: Post-treatment of the gradient alloy coating: annealing the cold sprayed gradient alloy coating at a temperature of 580° C. for 8 h;

[0111] Step 5: Surface processing of the gradient alloy coating: The surface of the gradient alloy coating is processed to be smooth, and the final total thickness of the coating is 0.65% of the diameter of the sliding bearing.

[0112] The above are only preferred embodiments of the present invention. It should be pointed out that any simple modification, change and equivalent changes made to the above embodiments according to the technical essence of the invention are still within the protection scope of the technical solution of the present invention.

[0113] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. The present disclosure is intended to cover any variations, uses or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary technical means in the art that are not disclosed in the present disclosure.

[0114] 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 gradient alloy coating, characterized in that: The gradient alloy coating comprises a base layer and a copper-based alloy surface layer, and the method comprises: The primer layer is first sprayed on the sliding bearing by using cold spraying technology to obtain the primer layer; A second spraying of copper-based alloy powder on the base layer is performed by cold spraying technology to obtain the copper-based alloy surface layer; Wherein, the thickness of the base layer is 12% to 20% of the thickness of the copper-based alloy surface layer.

2. The method for preparing a gradient alloy coating according to claim 1, characterized in that: The base layer is an aluminum alloy or a nickel-based alloy, and the copper-based alloy is a lead-tin-copper alloy, an aluminum-iron-copper alloy, a nickel-tin-copper alloy, or a bismuth-nickel-tin-copper alloy.

3. The method for preparing a gradient alloy coating according to claim 1, characterized in that: After obtaining the copper-based alloy surface layer, the method further comprises: Annealing the first gradient alloy coating composed of the base layer and the copper-based alloy surface layer to obtain a second gradient alloy coating; The surface of the second gradient alloy coating is processed and smoothed to obtain a third gradient alloy coating.

4. The method for preparing the gradient alloy coating according to claim 3, characterized in that: The thickness of the first gradient alloy coating is 0.3% to 0.8% of the diameter of the sliding bearing; the thickness of the third gradient alloy coating is 0.2% to 0.9% of the diameter of the sliding bearing.

5. The method for preparing the gradient alloy coating according to claim 3, characterized in that: The process parameters of the annealing treatment are: annealing temperature is 200° C. to 600° C., and annealing time is 2 h to 10 h.

6. The method for preparing a gradient alloy coating according to claim 1, characterized in that: The process parameters of the first spraying are: the spraying gas is nitrogen, argon or helium, the spraying temperature is 200° C. to 850° C., the spraying distance is 10 mm to 40 mm, and the spraying pressure is 3 MPa to 6 MPa.

7. The method for preparing a gradient alloy coating according to claim 1, characterized in that: The process parameters of the second spraying are: the spraying gas is nitrogen or argon, the spraying temperature is 500° C. to 950° C., the spraying distance is 20 mm to 30 mm, and the spraying pressure is 3.5 MPa to 6 MPa.

8. The method for preparing a gradient alloy coating according to claim 1, characterized in that: Before adopting the cold spraying process, the method further comprises: The base layer powder and the copper-based alloy powder are dried; the process parameters of the drying process are: a drying temperature of 80° C. to 100° C. and a drying time of 2 h to 4 h.

9. The method for preparing a gradient alloy coating according to claim 1, characterized in that: Before adopting the cold spraying process, the method further comprises: The surface of the sliding bearing substrate is sandblasted; the process parameters of the sandblasting are: the sandblasting grit is brown corundum, the mesh size is 20-60 mesh, the sandblasting pressure is 0.6MPa-0.8MPa, and the sandblasting distance is 50mm-100mm.

10. A gradient alloy coating, characterized in that: The gradient alloy coating is obtained by using the preparation method of the gradient alloy coating as described in claims 1 to 9 above.

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