A clad copper-based composite coating material, a preparation process and application thereof

Abstract

The application relates to the field of wind power bearing lubrication, and discloses a clad copper-based composite coating material, a preparation process and application of the clad copper-based composite coating material, which comprises the following components: 60-80% of aluminum bronze or tin bronze powder and 20-40% of a lubricating phase, wherein the lubricating phase is formed by mixing at least two kinds of powders selected from graphite, polyphenyl fat, bentonite, CaF2 and MoS2. The multiple-component lubricating phase is used to realize synergistic lubrication, the self-lubricating property of the coating is remarkably improved, and the friction coefficient is reduced; the lubricating phase is coated by the copper-based alloy powder, decomposition of the lubricating phase in the process of super-high-speed laser cladding is avoided, the functionality of the lubricating phase is ensured, and the service life of the coating is remarkably improved; and the technical problems of poor self-lubricating property and low bonding strength of existing sliding bearings in the field of wind power are solved.

Description

Technical Field

[0001] This invention relates to the field of wind turbine bearing lubrication technology, specifically to a coated copper-based composite coating material, its preparation process, and its application. Background Technology

[0002] In the field of modern wind power generation, wind turbine bearings, as key components, play a crucial role in the stable operation of the entire wind power system. However, currently, most wind turbine main shaft bearings and gearbox bearings rely on imported rolling bearings, which to some extent restricts the independent and controllable development of my country's wind power industry. Gearbox bearings require high reliability, long operating time (20 to 25 years), smooth operation, low noise, small size, light weight, and non-replaceability during their service life (replacement costs exceed the cost of the entire gearbox).

[0003] Rolling bearings have dominated wind power applications due to their standardized dimensions, convenient selection, stable quality, and good interchangeability. However, they also have drawbacks such as limited service life and large size. In contrast, sliding bearings are gradually emerging due to their low cost and high reliability. In wind turbine gearbox bearing applications, the advantages of sliding bearings are particularly prominent, and their market size is expected to grow rapidly.

[0004] However, wind turbine sliding bearings face extremely unique and complex environments during operation. On the one hand, wind power equipment is typically installed outdoors, whether on land or at sea, and must withstand various harsh weather conditions. On the other hand, the vibrations and impacts generated during wind turbine operation also place higher demands on the lubrication of sliding bearings. Currently, in addition to adding copper bushings to sliding bearings, copper-based alloy coatings are also prepared on the surface of sliding bearings through laser cladding. However, the lubrication effect is generally limited when using copper bushings or copper-based alloys as surface lubrication coatings, often requiring the preparation of a polymer lubricating layer on the surface. However, adding a polymer lubricating layer inevitably increases the coating preparation process, making the production process more complex and correspondingly increasing costs.

[0005] More importantly, it is difficult to precisely control the bonding quality and performance gradient between layers during the preparation of multi-layer coating structures. Uneven bonding force between layers may lead to peeling, delamination and other phenomena during use, thus making it impossible to effectively guarantee the quality of the gradient layer. Once the coating has problems, it will directly affect the lubrication performance of the sliding bearing, leading to increased friction and wear, which in turn shortens the service life of the sliding bearing and reduces the reliability and operating efficiency of wind power equipment.

[0006] These problems have severely restricted the further development of lubrication technology for wind turbine sliding bearings, and there is an urgent need for an innovative solution to improve the lubrication performance of wind turbine sliding bearings and enhance their reliability and service life under complex working conditions. Summary of the Invention

[0007] The present invention aims to provide a coated copper-based composite coating material, its preparation process and its application, in order to solve the technical problems of poor self-lubricating performance and low bonding strength of existing sliding bearings in the wind power field.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A self-lubricating material, by mass fraction, comprises the following components: 60-80% aluminum bronze or tin bronze powder, and 20-40% lubricating phase, wherein the lubricating phase is a mixture of at least two powders selected from graphite, polystyrene, bentonite, CaF2, and MoS2.

[0010] Preferably, it comprises 60% aluminum bronze powder, 40% graphite and CaF2 mixed powder, wherein the graphite content in the mixed powder is 40-60%, and the balance is CaF2.

[0011] Preferably, it comprises 50% tin bronze powder, 50% polystyrene, CaF2 and MoS2 mixed powder, wherein the polystyrene content in the mixed powder is 30-50%, the CaF2 content is 10-20%, and the balance is MoS2.

[0012] Preferably, it comprises 70% aluminum bronze powder, 30% graphite, polystyrene, bentonite and CaF2 mixed powder, wherein the graphite content in the mixed powder is 30-50%, the polystyrene content is 20-30%, the bentonite content is 10-15%, and the balance is MoS2.

[0013] This invention also provides a method for preparing coated copper-based composite powder, using a self-lubricating material as the substrate, comprising the following steps:

[0014] S1. Copper-based composite powder is prepared by ball milling, wherein the mass percentage of copper-based powder to lubricating phase ball material is 10:1-15:1.

[0015] S2. Preparation of copper-based composite spherical powder: The composite powder from step 1 is made into a slurry, and then ground to obtain a uniformly dispersed suspension slurry; the suspension slurry is sent to a spray drying tower for spray drying, and the inlet temperature of the drying tower is 100-200℃ to obtain agglomerated spherical powder; the agglomerated powder is then dried and kept at the temperature for 5-10 hours, and 100-150μm powder is sieved to obtain copper-based composite spherical powder;

[0016] S3. Preparation of nickel-coated copper-based composite spherical powder: The composite powder of copper-based alloy and lubricating phase is coated by chemical plating to obtain nickel-coated copper-based composite spherical powder.

[0017] Preferably, the copper-based composite powder obtained in step 1 is spherical with a particle size of 90-120 μm. When the particle size is controlled within this range, the powder's flowability and melting properties are optimal, which facilitates improving the quality of subsequent laser cladding.

[0018] Preferably, the nickel-coated copper-based composite spherical powder obtained in step 3 has a coating layer thickness of 2-5 μm.

[0019] A coated copper-based composite coating material is obtained by the above preparation method.

[0020] This invention also provides a preparation process for a coated copper-based composite coating material, which uses ultra-high-speed laser cladding to clad the composite coating material onto the substrate surface to form a composite coating, including the following steps.

[0021] S1. The area of ​​the substrate to be clad is subjected to coarse grinding and fine grinding in one step to obtain a pretreated substrate;

[0022] S2. The pretreated substrate from step one is subjected to ultra-high-speed laser cladding using nickel-coated copper-based composite spherical powder to form a nickel-based wear-resistant self-lubricating coating. The process parameters for ultra-high-speed laser cladding are as follows: nitrogen or argon is used as the powder feeding gas and protective gas, coaxial powder feeding is used, laser power is 1-5kW, spot diameter is 1.5-4.5mm, cladding linear speed is 10-40m / min, powder feeding rate is 20-50g / min, and powder feeding gas flow rate is 10-15L / min.

[0023] S3. The cladding layer is machined to achieve a surface roughness Ra of 0.8-1.6.

[0024] Preferably, the thickness of the nickel-based wear-resistant self-lubricating coating obtained in step 2 is 1.5mm-1.8mm. When the coating thickness exceeds 1.8mm, on the one hand, the preparation cost will increase, and on the other hand, the coating is prone to cracking and peeling.

[0025] This invention also provides an application of a coated copper-based composite coating material in the wind power field, which is clad onto the surface of a sliding bearing to form a wear-resistant and self-lubricating coating.

[0026] Inventive concept:

[0027] In the wind power field, sliding bearings have advantages over rolling bearings in terms of lower cost and higher reliability. However, their high reliability is closely related to their self-lubricating properties. To ensure the self-lubricating properties of sliding bearings, copper-based alloy coatings or polymer lubricating layers are commonly used on the surface of the sliding bearing. The polymer lubricating layer mainly utilizes the good lubrication properties of the polymer material itself to reduce the coefficient of friction. The molecular chain structure of the polymer material allows it to form a transfer film on the surface of the friction pair during friction. This transfer film can effectively separate the two friction surfaces, reduce direct contact between metals, and thus reduce friction and wear. The lubrication effect of the polymer lubricating layer is relatively stable. However, the physical and chemical properties of the polymer material and the metal bearing surface are very different, resulting in limited bonding force. Furthermore, under harsh conditions such as high temperature and high load, the polymer lubricating layer is prone to aging, wear, and peeling, which leads to a decrease in bonding force.

[0028] Therefore, a relatively innovative solution is to add a lubricating phase to copper-based composite powder. Copper-based alloy coatings themselves have certain metallic properties, which allows the heat generated during friction to be dissipated more easily, avoiding local overheating. At the same time, copper-based alloy coatings have good mechanical properties and high bonding strength, and can withstand high loads. The lubricating phase can still play a friction-reducing role under high loads. Compared with copper-based alloy coatings or polymer lubricating layers, adding a lubricating phase to copper-based composite powder has multiple advantages such as high bonding strength and good lubrication performance.

[0029] CN116752076A discloses a method for improving the self-lubricating properties and wear-resistant performance of metal parts by adding lubricating and wear-resistant phases to copper-based powder. It provides a wear-resistant self-lubricating material, a wear-resistant self-lubricating composite coating, its preparation method, and mechanical metal parts. The material comprises the following components: 10%–20% nickel-coated graphite powder; 10%–20% spherical alumina powder; and the balance being copper-aluminum alloy powder. This invention enables the formation of a metal-based wear-resistant self-lubricating composite coating with good self-lubricating properties, wear-resistant performance, and a relatively large thickness on the surface of mechanical assembly / equipment metal parts.

[0030] However, the following technical problems still exist when applying the above technology to the sliding bearings in the wind power field of this invention:

[0031] 1. Low bonding strength: This technology uses plasma spraying process, and its bonding strength is only about 35MPa at most. The minimum bonding strength required in the wind power field is 100MPa. Therefore, the existing technology cannot be used to prepare self-lubricating coatings on the surface of wind turbine sliding bearings.

[0032] 2. Wear of sliding bearings by wear-resistant spherical alumina: The low-speed, heavy-load service conditions in the wind power field cause wear on the surface coating of sliding bearings, resulting in the shedding of the hard wear-resistant alumina phase. Once the hard wear-resistant phase falls off, it will cause secondary scratches on the surface of the sliding bearing, making the sliding bearing risk of seizing.

[0033] 3. Poor lubrication effect: There is only graphite as the lubricating phase. In the service environment of wind power, when the operating temperature rises, the graphite lubricating phase is prone to decomposition, which reduces the service life.

[0034] In summary, the inventors have conducted extensive research on the formulations, preparation methods, and coating techniques of existing copper-based composite coating materials, and have developed a coating-type copper-based composite coating with high lubricity, high bonding strength, and long service life. The coefficient of friction can be as low as 0.15, and the bonding strength can reach as high as 250 MPa. Through use and experimental verification, the service life has been doubled, and no problems such as coating peeling have occurred during service.

[0035] Technical principles and beneficial effects:

[0036] 1. Synergistic lubrication of multi-component lubricants:

[0037] In the preparation of copper-based composite powders, various lubricating phases are selected, such as two of graphite, polystyrene grease, bentonite, CaF2, or MoS2, which can achieve complementary properties of different lubricating phases. Graphite has a layered structure with weak interlayer forces, making it easy to slide during friction, thus playing a role in reducing friction; polystyrene grease has good high-temperature resistance and a low coefficient of friction, maintaining stable lubrication performance under high-temperature conditions; bentonite has adsorption and expansion properties, which can form an adsorption film on the friction surface, enhancing the lubrication effect; CaF2 and MoS2 have excellent solid lubrication properties, effectively reducing the coefficient of friction under harsh conditions such as high load and high temperature. The characteristics of these different lubricating phases complement each other. When they coexist in the coating, they can exert their respective advantages under different operating conditions (such as temperature changes, load changes, etc.), forming a synergistic lubrication effect.

[0038] Furthermore, the various lubricating phases in the coating are not simply mixed, but uniformly dispersed through processes such as ball milling, forming a composite lubrication system. During friction, as the friction surfaces wear and temperature changes, different lubricating phases can play their roles sequentially or simultaneously. For example, in the initial stage, the layered structure of graphite can initially provide friction reduction. As the temperature rises, the high-temperature lubrication properties of polystyrene begin to play a dominant role, while CaF2 and MoS2 undertake the main load-bearing and lubrication tasks in high-load areas. The adsorption film of bentonite helps maintain the stability of the entire lubrication system, thereby achieving synergistic lubrication and significantly improving the self-lubricating properties of the coating.

[0039] 2. Reduce coating hardness:

[0040] Most of the aforementioned lubricating phases have relatively low hardness. For example, graphite is soft and when it is evenly distributed in the coating as fine particles, it can reduce the overall hardness of the coating to a certain extent. When the coating is subjected to external force, these soft lubricating phases can deform and flow to a certain extent, absorb some energy, and prevent the coating from brittle fracture or severe wear due to excessive hardness.

[0041] Compared with traditional high-hardness coatings, the multi-component lubricating phase coating in this technology has a lower hardness when bonded to the substrate, thus having less impact on the substrate hardness. During friction, the hardness difference between the coating and the substrate is relatively small, which helps to reduce coating peeling or substrate wear caused by hardness mismatch, thereby improving the overall synergistic performance of the coating and the substrate and further ensuring the durability of the lubrication effect.

[0042] 3. Copper-based alloy powder coating of the lubricating phase prevents its decomposition:

[0043] In the preparation of nickel-coated copper-based composite spherical powder, the copper-based composite spherical powder first encapsulates the lubricating phase inside. This encapsulation structure acts as a physical barrier for the lubricating phase, reducing its direct contact with the external high-temperature environment during the subsequent ultra-high-speed laser cladding process. The high temperature and energy generated during laser cladding mainly act on the copper-based alloy powder and the outer nickel layer, while the internal lubricating phase experiences relatively less thermal shock. This effectively prevents the lubricating phase from decomposing due to high temperature, which helps to ensure the performance of the lubricating phase.

[0044] In addition, copper-based alloy powder and nickel layer have certain thermal conductivity, but their thermal conductivity is relatively slow compared to direct exposure to laser beam. When laser energy is transferred to the coated structure, copper-based alloy powder and nickel layer will absorb and disperse some of the heat, slowing down the heat transfer rate to the internal lubricating phase, so that the lubricating phase exists in a relatively low temperature environment, reducing the possibility of the lubricating phase reaching the decomposition temperature.

[0045] Finally, the outer nickel layer not only possesses excellent wear resistance but also exhibits a certain degree of chemical stability. During laser cladding, the nickel layer prevents oxidizing substances such as oxygen in the air from contacting the internal lubricating phase, thus avoiding chemical reactions such as oxidation and decomposition of the lubricating phase. Simultaneously, the presence of the nickel layer alters the internal chemical environment of the cladding structure, allowing the lubricating phase to be preserved in a relatively stable chemical atmosphere, further enhancing its stability during high-temperature cladding.

[0046] 4. Ultra-high-speed laser cladding technology helps reduce the thermal impact on the substrate:

[0047] On the one hand, the cladding linear speed of ultra-high-speed laser cladding technology reaches 10-40 m / min, which is significantly higher than that of traditional laser cladding, thus improving cladding efficiency. During the cladding process, the laser acts on the substrate surface and powder for an extremely short time, and the energy input per unit area is completed in a short time. This means that the substrate absorbs limited heat in a short time, and there is not enough time to conduct a large amount of heat to the interior of the substrate, thereby reducing heat accumulation and reducing the thermal impact on the substrate.

[0048] On the other hand, due to the fast cladding speed, the cladding coating quickly leaves the laser-affected area and enters the surrounding environment for rapid cooling. This rapid cooling process allows the substrate to quickly recover to a lower temperature after being heated, reducing changes in the substrate structure caused by prolonged high temperatures (such as grain growth, phase transformation, etc.), which is beneficial to maintaining the original properties of the substrate, such as strength and hardness. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the bonding strength of the copper-based composite coating of the present invention.

[0050] Figure 2 This is a cross-sectional morphology diagram of the copper-based composite coating in Experimental Example 1# of the present invention;

[0051] Figure 3 The friction coefficient curve of Experimental Example 1# of this invention after dry friction grinding with a Ф3mm GCr15 steel ball. Detailed Implementation

[0052] This invention provides a coated copper-based composite coating material and its preparation process. Compared with existing technologies, by employing a multi-component lubricating phase, a synergistic lubrication effect is achieved, significantly improving the self-lubricating properties of the coating and reducing its hardness. Furthermore, by coating the lubricating phase with copper-based alloy powder, the decomposition of the lubricating phase during ultra-high-speed laser cladding is avoided. In other words, by optimizing the coating material formulation, preparation method, and ultra-high-speed laser cladding, the bonding strength can be guaranteed to meet or even far exceed the standard requirements, while also preventing the decomposition of the lubricating phase during cladding, ensuring the functionality of the lubricating phase and significantly improving the coating's service life.

[0053] A self-lubricating material, by mass fraction, comprises the following components: 60-80% aluminum bronze or tin bronze powder, and 20-40% lubricating phase, wherein the lubricating phase is a mixture of at least two powders selected from graphite, polystyrene, bentonite, CaF2, and MoS2.

[0054] Specifically, the combination of the components of the self-lubricating material in this invention is detailed in Table 1.

[0055] Table 1: Composition of Self-Lubricating Materials (wt.%)

[0056]

[0057]

[0058] A method for preparing a coated copper-based composite powder includes the following preparation steps:

[0059] Step 1: Preparation of copper-based composite powder:

[0060] Weigh 60-80% by mass of aluminum bronze (copper (Cu), aluminum (Al), iron (Fe), nickel (Ni)) or tin bronze powder (CuSn4), and 20-40% by mass of two of the following mixed powders: graphite, polystyrene, bentonite, CaF2, or MoS2. Place them in a ball mill jar for ball milling and mixing at a ball-to-powder ratio of 10:1-15:1. Add 2-4% by mass of stearic acid as a process control agent during mixing. The ball milling speed is 200-800 rpm, and the ball milling time is 24-96 h, finally forming a copper-based composite powder. The copper-based composite powder obtained in this invention is spherical with a particle size of 90-120 μm.

[0061] Step 2: Preparation of copper-based composite spherical powder:

[0062] Add 1-5% by weight of binder and 30-70% by weight of deionized water to the copper-based composite powder prepared in step one, mix and stir to form a slurry, and grind to obtain a uniformly dispersed suspension slurry. Specifically, the binder used in this invention is polyethylene glycol. Send the suspension slurry to a spray drying tower for spray drying. The inlet temperature of the drying tower is 100-200℃ to form agglomerated powder. Dry the prepared agglomerated powder in a drying oven at 100-150℃ for 5-10 hours, and sieve 100-150μm powder to obtain spherical copper-based composite spherical powder.

[0063] Step 3: Preparation of nickel-coated copper-based composite spherical powder:

[0064] The spherical copper-based composite spherical powder obtained in step two is soaked in a KOH solution with a pH of 8-10 for 2-10 minutes. In this invention, it is preferred to soak in a KOH solution with a pH of 8 for 2 minutes. After filtering the powder, it is added to a zinc sulfate solution and soaked for 10-60 minutes, and then filtered again, preferably soaked for 10 minutes. In this case, 2-20 wt% tartaric acid is added to the zinc sulfate solution, preferably 2 wt%.

[0065] Add a nickel sulfate solution to a reactor vessel, wherein the nickel ion concentration in the solution is 20-100 g / L, preferably 20 g / L. Add spherical copper-based powder while heating and stirring the solution. When the solution is heated to 50-90°C, add sodium hypophosphite at a rate of 1-2 L / min to adjust the pH of the solution to 5-7. Preferably, when the solution is heated to 50°C, add sodium hypophosphite at a rate of 1 L / min to adjust the pH of the solution to 7.

[0066] Once the solution becomes colorless and transparent, stop adding sodium hypophosphite and continue the reaction at 300-600℃ for 30-60 minutes. During the reaction, stir thoroughly at a rotor speed of 50-80 rpm to promote the reaction. When the speed is below 50 rpm, the reaction is incomplete, and when the speed is above 80 rpm, the reaction solution is prone to overflow. After the above reaction time, nickel-coated copper-based composite spherical powder is obtained, wherein the coating thickness is 2-5 μm. The powder is then filtered dry and reduced by passing hydrogen gas through it.

[0067] Using the above preparation method, copper-based alloys and lubricating phases under each combination in Table 1 are prepared into coated copper-based composite powders. The preparation steps and process parameters are detailed in Table 2.

[0068] Table 2: Preparation process parameters for various lubricant material combinations

[0069]

[0070]

[0071] The present invention also provides a coated copper-based composite coating material, which is obtained by the preparation method described in steps 1-3 above.

[0072] This invention also provides a preparation process for a coated copper-based composite coating material, which uses ultra-high-speed laser cladding to clad the coated copper-based composite coating material onto the substrate surface to form a composite coating, including the following steps:

[0073] Step 1: Perform coarse grinding and fine grinding on the area of ​​the substrate to be clad in one pass to obtain a pretreated substrate;

[0074] Step 2: The pretreated substrate from Step 1 is subjected to ultra-high-speed laser cladding using nickel-coated copper-based composite spherical powder to form a nickel-based wear-resistant self-lubricating coating. The process parameters for ultra-high-speed laser cladding are as follows: nitrogen or argon is used as the powder feeding gas and protective gas; coaxial powder feeding is employed; laser power is 1-5 kW; spot diameter is 1.5-4.5 mm; cladding linear velocity is 10-40 m / min; powder feeding rate is 20-50 g / min; and powder feeding gas flow rate is 10-15 L / min.

[0075] Specifically, in actual use, the laser power can be selected as 5kW, the spot diameter as 1.5mm, the cladding linear speed as 10m / min, the powder feeding rate as 20g / min, and the powder feeding gas flow rate as 10L / min; or the laser power can be selected as 1kW, the spot diameter as 4.5mm, the cladding linear speed as 40m / min, the powder feeding rate as 50g / min, and the powder feeding gas flow rate as 15L / min; the present invention prefers the former process parameters for cladding.

[0076] Step 3: Machining the cladding layer to achieve a surface roughness Ra of 0.8-1.6. Specifically, in this invention, Ra can be 0.8 or 1.6, with Ra preferably being 0.8.

[0077] The present invention also provides an application of a coated copper-based composite coating material in the wind power field, which is clad onto the surface of a sliding bearing to form a wear-resistant and self-lubricating coating with a thickness of 1.5mm-1.8mm. This composite coating significantly improves the self-lubricating performance, reliability and service life of the sliding bearing.

[0078] Using the above cladding process, the coated copper-based composite material obtained in Table 2 was clad onto the substrate surface to form a lubricating coating (coating thickness of 1.5mm-1.8mm). The various properties of the coating were tested, and the experimental results are shown in Table 3.

[0079] Table 3: Performance Indicators of Coated Copper-Based Composite Coatings under Various Combination Methods and Processing Conditions

[0080]

[0081]

[0082] Specifically, the testing methods for each indicator in Table 3 are as follows:

[0083] (1) Test method for average friction coefficient: The friction test is a reciprocating dry friction test with a reciprocating amplitude of 5 mm, a reciprocating speed of 15 mm / min, a test time of 60 min, and a load of 1000 g.

[0084] (2) Test method for bond strength: Non-standard plate-shaped tensile specimens are processed by wire cutting, and their specific dimensions are as follows: Figure 1 As shown. Then, the surface of the plate-shaped tensile specimen was polished sequentially using 400#, 800#, and 1200# metallographic wet sandpaper, paying particular attention to the arc transition section. The final surface roughness of the specimen was ~0.5 μm. Finally, the specimen was fixed using a special fixture, and its strength was tested on a universal testing machine at a tensile speed of 0.5 mm·min. -1At least five specimens should be tested, and their average value should be taken as the strength of the specimen.

[0085] (3) Test method of wear rate: After the wear test, the wear marks are obtained by laser confocal microscope. The wear area S of the wear marks is calculated by integration using Origin software. Then, the wear rate of the material is estimated according to Formula 1.

[0086]

[0087] In Formula 1, Δv is the wear volume of the material, F is the pressure during the wear process, and L is the friction distance. Δv is obtained by solving for the cross-sectional area S of the wear track and the wear radius R.

[0088] In the wind power field where this invention is applied, the basic technical indicators for the application of lubricating coatings for sliding bearings are as follows: bonding strength of 100MPa, average friction coefficient of 0.15, and hardness of 150HV.

[0089] Based on Table 1-3, the following conclusions can be drawn:

[0090] 1. When the self-lubricating material uses Combination 1, according to Examples 1#-2#, the bonding strength of the lubricating coating is greater than 200 MPa, the average coefficient of friction is less than 0.21, and the wear rate and hardness of the coating are in a relatively ideal state. Furthermore, the lubricating phase is uniformly distributed and does not decompose after cladding, resulting in a long service life for the coating. This is mainly due to the synergistic effect of the lubricating phase, and the formation of spherical powder with a particle size of 90-120 μm during the preparation process. The spherical powder is then electrolessly nickel-plated, controlling the coating thickness to be 2-5 μm. This coating structure not only protects the lubricating phase from high-temperature decomposition but also makes the bond between the coating and the substrate tighter, thereby improving the bonding strength.

[0091] As shown in Experiments 3-5, the bonding strength and average coefficient of friction of the lubricating coating were significantly reduced, resulting in greater wear and higher hardness. Specifically, the bonding strength of Experiments 3 and 5 was lower than the minimum requirement of 100 MPa for wind power applications. This is mainly because the powder prepared in Experiment 3 was flat. Compared to spherical powder, flat powder has poorer flowability and filling properties, and cannot be evenly distributed on the substrate surface during the cladding process. This leads to an uneven coating structure, affecting the bonding strength between the coating and the substrate (only 75 MPa). The uneven coating structure also results in uneven local stress during friction, exacerbating wear and increasing the wear rate. Furthermore, the hardness distribution is uneven, resulting in a higher overall hardness.

[0092] 2. When the self-lubricating material uses combination 2-5, according to experimental examples 6#-9#, the bonding strength of the lubricating coating is about twice that of the basic index of 100MPa. The increased bonding strength makes it less likely to fall off during use, thus improving the service life of the coating. Furthermore, due to the synergistic effect of multiple lubricating phases, the coefficient of friction is effectively reduced, wear is reduced, and the wear rate is kept at a low level. At the same time, the presence of multiple lubricating phases makes the coating hardness moderate, which ensures the wear resistance of the coating without causing brittle fracture or substrate wear due to excessive hardness.

[0093] 2. When the self-lubricating material is used as control 1-4, according to experimental examples 10#-13#, the lubricating phase distribution of the lubricating coating after cladding is poor and partial decomposition occurs; the bonding strength of the coating is greatly reduced and lower than the application requirements; the coefficient of friction, wear rate and hardness are increased and all exceed the application requirements, so it cannot be directly used in the wind power field.

[0094] The main reason is:

[0095] (1) In its combination, the lubricating phase is singular and the proportion is inappropriate: Control 1 contains only 20% graphite as the lubricating phase. Under the complex operating conditions in the wind power field, a single lubricating phase cannot meet multiple needs. When the operating temperature rises, the graphite lubricating phase is prone to decomposition, resulting in a decrease in lubrication effect, an increase in the friction coefficient (0.38), and aggravated wear. Control 3 contains 30% bentonite as the lubricating phase. Although bentonite has adsorption and expansion properties, when used alone in the coating, it cannot provide sufficient lubrication and load-bearing capacity, affecting the overall performance of the coating.

[0096] (2) Issues with powder preparation and processing technology: In controls 1 and 3, the ball milling process resulted in insufficient powder mixing, and the high temperature at the air inlet of the drying tower and the long holding time led to a flat powder shape, affecting the density and uniformity of the coating and reducing the bonding strength. In controls 2 and 4, the high temperature and long time of the electroless nickel plating reaction resulted in an excessively thick coating (10 μm for control 2 and 15 μm for control 4), causing stress concentration and affecting the stress transfer between the coating and the substrate, thus significantly reducing the bonding strength. In addition, the lubricating phase in the control combinations had poor uniformity of distribution and was prone to partial decomposition during the cladding process, further deteriorating the coating performance and making it unable to meet the coating requirements of the wind power field.

[0097] In summary, the composition of the lubricating phase is crucial to coating performance. A diverse and appropriately proportioned combination of lubricating phases can achieve synergistic lubrication, reduce the coefficient of friction and wear rate, optimize hardness, and improve coating stability, thereby extending service life. The ball milling process (ball-to-powder ratio, rotation speed, and time), powder shape control, and electroless nickel plating process (coating thickness and related parameters) in the preparation process have a significant impact on coating performance. In particular, when the powder coating thickness is too high, the coating performance is significantly reduced. Reasonable process parameters can ensure uniform distribution of the lubricating phase, form a good coating structure, improve the bonding strength between the coating and the substrate, and ensure the reliability of the coating during use.

[0098] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for producing a coated copper-based composite powder, characterized by: The self-lubricating material is used as a base material, and nickel is used as a cladding layer; the method comprises the following steps: S1, the self-lubricating material is prepared into copper-based composite powder by a ball milling process, wherein the mass percentage of copper-based powder to lubricating phase is 10:1-15:1; the self-lubricating material comprises the following components in terms of mass fraction: 60-80% of aluminum bronze or tin bronze powder, and 20-40% of lubricating phase, wherein the lubricating phase is formed by mixing at least two powders selected from graphite, polyphenyl fat, bentonite, CaF2 and MoS2; S2, the copper-based composite spherical powder is prepared: the copper-based composite powder in S1 is made into slurry, and a uniformly dispersed suspension slurry is prepared by grinding; the suspension slurry is sent to a spray drying tower for spray drying, the temperature of the air inlet of the drying tower is 100-200℃, and agglomerated spherical powder is obtained; the agglomerated powder is dried, the holding time is 5-10h, the 100-150µm powder is screened, and the copper-based composite spherical powder is obtained; S3, the nickel-coated copper-based composite spherical powder is prepared: the composite powder of copper-based alloy and lubricating phase is coated with nickel by chemical plating, and the nickel-coated copper-based composite spherical powder is obtained.

2. The method of claim 1, wherein the coated copper-based composite powder is prepared by the steps of: The self-lubricating material comprises 60% of aluminum bronze powder and 40% of mixed powder of graphite and CaF2, and the content of graphite in the mixed powder is 40-60%, and the balance is CaF2. ​ 3. The method of claim 1, wherein the coated copper-based composite powder is prepared by the steps of: (a) preparing a copper-based composite powder; (b) preparing a coating solution; (c) coating the copper-based composite powder with the coating solution; and (d) drying the coated copper-based composite powder. The self-lubricating material comprises 50% of tin bronze powder and 50% of mixed powder of polyphenyl fat, CaF2 and MoS2, the content of polyphenyl fat in the mixed powder is 30-50%, the content of CaF2 is 10-20%, and the balance is MoS2.

4. The method of claim 1, wherein the coated copper-based composite powder is prepared by the steps of: (a) preparing a copper-based composite powder; (b) preparing a coating solution; (c) coating the copper-based composite powder with the coating solution; and (d) drying the coated copper-based composite powder. The self-lubricating material comprises 70% of aluminum bronze powder and 30% of mixed powder of graphite, polyphenyl fat, bentonite and CaF2, the content of graphite in the mixed powder is 30-50%, the content of polyphenyl fat is 20-30%, the content of bentonite is 10-15%, and the balance is MoS2.

5. The method for preparing a coated copper-based composite powder according to claim 1, characterized in that: The copper-based composite powder prepared in S1 is spherical, and the particle size of the powder is 90-120µm.

6. The method for preparing a coated copper-based composite powder according to claim 5, characterized in that: The thickness of the nickel cladding layer in the nickel-coated copper-based composite spherical powder prepared in S3 is 2-5µm.

7. A coated copper-based composite powder, characterized by: The method is obtained by any one of claims 1-6.

8. A process for preparing a cladded copper-based composite coating material, wherein the nickel-coated copper-based composite spherical powder of claim 7 is used to form a composite coating on the surface of a substrate by ultra-high-speed laser cladding, characterized in that: The method comprises the following steps, Step one, the to-be-cladded area of the base body is sequentially subjected to rough grinding and fine grinding to obtain a pretreated base body; Step two, the pretreated base body in step one is subjected to ultra-high-speed laser cladding by using the nickel-coated copper-based composite spherical powder to form a nickel-based wear-resistant and self-lubricating coating; wherein the process parameters of the ultra-high-speed laser cladding are as follows: nitrogen or argon is used as the powder feeding gas and the protective gas, the coaxial powder feeding mode is used, the laser power is 1-5kW, the spot diameter is 1.5-4.5mm, the cladding line speed is 10-40m / min, the powder feeding rate is 20-50g / min, and the powder feeding gas flow is 10-15L / min; Step three, the cladded layer is subjected to machining treatment, and the surface roughness Ra of the coating is 0.8-1.

6.

9. The process for preparing a cladded copper-based composite coating material as claimed in claim 8, wherein: The thickness of the nickel-based wear-resistant and self-lubricating coating obtained in step two is 1.5-1.8mm.

10. Use of a clad copper-based composite coating material, characterized in that: The prepared coated copper-based composite coating material of the process of claim 8 or 9 is applied in the field of wind power, and is cladded on the surface of a sliding bearing to form a wear-resistant self-lubricating coating, and the coating thickness is 1.5-1.8 mm.

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