A method for preparing a wear-resistant coating on an outer housing of a speed reducer

Abstract

The application discloses a kind of preparation methods of wear-resistant coating of speed reducer outer shell, belong to surface engineering and mechanical manufacturing technical field, to solve the weak coating adhesion of existing speed reducer outer shell, wear and lubrication performance imbalance, high temperature preparation easily leads to shell deformation and poor adaptability of extreme working condition technical problem, core scheme includes: ternary composite coating material configuration;Bionic porous structure construction;Low-temperature composite process: using "sand blasting pretreatment+low temperature plasma spraying+vacuum low-temperature curing" composite process, the whole preparation temperature is controlled at 120-180 DEG C;Multi-scene adaptation: by adjusting material component realizes remanufacturing repair and customization application of extreme working condition, the coating of the application is combined high, wear resistance is improved, and shell deformation can be avoided, suitable for strengthening and repair of new and old speed reducer outer shell, with significant economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of surface engineering and mechanical manufacturing technology, and specifically relates to a method for preparing a wear-resistant coating for a speed reducer housing, which is particularly suitable for strengthening, repairing and adapting to extreme working conditions of speed reducer housings. Background Technology

[0002] As a core component of mechanical transmission systems, speed reducers are widely used in industrial production, engineering machinery, transportation, and other fields. The speed reducer housing, as the core structure protecting internal gears, bearings, and other critical components, must not only withstand assembly stress and working loads but also resist dust, corrosive media, and frictional wear from surrounding parts. Therefore, the wear resistance and corrosion resistance of the housing surface directly determine the overall service life and operational reliability of the speed reducer.

[0003] To improve the surface properties of the gearbox housing, existing technologies often employ surface coating techniques for strengthening, including surface spraying, laser cladding, electroplating / chemical plating, and composite coatings. However, these existing technologies have many shortcomings in practical applications: First, the coating has weak adhesion to the substrate and is prone to peeling off after long-term use. For example, the bonding strength of existing organic coatings such as epoxy resin and fluorocarbon resin is mostly below 40MPa, which is difficult to meet the long-term wear resistance requirements. Second, there is an imbalance between wear resistance and lubrication performance. The friction coefficient of purely wear-resistant coatings is high, which can easily lead to increased wear of mating parts, while self-lubricating coatings have insufficient wear resistance. Third, the preparation process is mostly a high-temperature process. For example, the temperature of processes such as laser cladding and conventional thermal spraying exceeds 500℃, which can easily cause defects such as deformation and cracks in the gearbox housing made of cast iron and cast steel, affecting the assembly accuracy. Fourth, the process is complex and costly. For example, laser cladding equipment requires large investment and has low processing efficiency, making it difficult to achieve mass production. Fifth, the adaptability to working conditions is poor. Existing coatings are mostly designed for conventional environments, and their performance degrades quickly under extreme working conditions. Furthermore, there is a lack of special coating technology for the remanufacturing and repair of used gearbox housings.

[0004] Furthermore, existing research on wear-resistant coatings for speed reducers largely focuses on internal components such as gears and bearings, with limited dedicated coating technologies specifically for the outer casing. The complex structure of the speed reducer casing, including curved surfaces and irregular shapes like holes, places higher demands on the uniformity and formability of the coating. Simultaneously, the uneven wear on the casings of used speed reducers necessitates a dual approach of repair and reinforcement, which existing coating technologies struggle to meet.

[0005] Biomimetic porous structures are widely found in nature. For example, the surface structures of organisms like desert beetles possess excellent wear resistance, cushioning, and self-lubricating properties. Applying these structures to surface design can effectively improve the overall performance of coatings. Simultaneously, low-temperature fabrication processes can avoid thermal deformation of the substrate, and ternary composite material systems can achieve synergistic optimization of wear resistance, lubrication, and corrosion resistance. Therefore, developing a method for preparing gearbox housing coatings that integrates ternary composite coating materials, biomimetic porous structures, and low-temperature fabrication processes, and is adaptable to remanufacturing and extreme operating conditions, has significant practical implications and application value. Summary of the Invention

[0006] To address the technical problems of existing gearbox housing coatings, such as weak adhesion, imbalance between wear resistance and lubrication performance, easy deformation of the housing due to high-temperature preparation, poor adaptability to extreme working conditions, and lack of remanufacturing adaptability, this invention provides a method for preparing a wear-resistant coating for gearbox housings. Through synergistic innovation in material system, structural design, and preparation process, the coating performance is comprehensively improved and adapted to multiple scenarios.

[0007] To achieve the above objectives, this invention provides a method for preparing a wear-resistant coating for a gearbox housing. The core technical solution is a "ternary composite coating material + surface biomimetic papillary wear-resistant structure + low-temperature composite process." Furthermore, by adjusting the material composition, remanufacturing and customized applications for extreme working conditions are achieved. The method specifically includes the following steps: Substrate pretreatment: The substrate of the reducer housing is cleaned and roughened by sandblasting. Ternary composite coating material preparation: Weigh out 65-75% metal matrix, 18-25% ceramic reinforcement phase, and 3-7% solid lubricating phase according to the mass ratio, and mix them evenly to obtain ternary composite powder; wherein, the metal matrix is ​​Ni60 alloy or NiCrBSi alloy powder, the ceramic reinforcement phase is nano Al2O3 or tungsten carbide with silane coupling agent surface modification treatment, and the solid lubricating phase is graphene or MoS2. Preparation of biomimetic papillary wear-resistant structure: A mushroom-shaped biomimetic papillary wear-resistant structure is formed on the surface of a pre-treated substrate or the surface of a pre-formed coating layer by laser cladding process; Low-temperature composite spraying: The ternary composite powder is sprayed onto the surface of a substrate with the biomimetic papillary wear-resistant structure using a low-temperature plasma spraying process to form an initial coating layer. The substrate temperature is controlled to be ≤180℃ during the spraying process. Low-temperature curing: The workpiece with the initial coating layer is placed in a vacuum environment for step-by-step temperature curing. Post-treatment: The cured coating is then repaired and cleaned.

[0008] The surface modification treatment of the ceramic reinforcing phase specifically involves: adding the ceramic reinforcing phase to a 1.5-3% (w / w) silane coupling agent ethanol solution and ultrasonically dispersing it, followed by drying it at 85-100°C to constant weight.

[0009] The biomimetic papillary wear-resistant structure is mushroom-shaped, where d1 is the diameter of the cylindrical segment at the bottom of the papillary; d2 is the maximum width of the umbrella-shaped segment at the top of the papillary; H is the total height of the papillary; h1 is the height of the cylindrical segment at the bottom of the papillary; h2 is the height of the umbrella-shaped segment at the top of the papillary; R1 is the radius of the transition fillet between the bottom cylindrical segment and the top umbrella-shaped segment; R2 is the outer radius of the top umbrella-shaped segment; s is the center-to-center distance between adjacent papillae; and the diameter d1 of the cylindrical segment at the bottom of the papillary is a reference parameter. d2=d1×k1 k1 is the biomimetic width magnification factor, with a value range of 1.2 ≤ k1 ≤ 1.5; H=d1×k2 k2 is the biomimetic aspect ratio coefficient, with a value range of 1.0≤k2≤1.5, matching the short, sturdy, and wear-resistant structural characteristics of beetle papillae; h1=R1=d1×k3 k3 is the transition fillet factor, with a value range of 0.4≤k3≤0.5, to ensure a smooth structural transition; h2=H-h1 R2=2d2.

[0010] The parameters of the low-temperature plasma spraying process are as follows: spraying power 38-45kW, spraying distance 120-160mm, powder feeding rate 22-30g / min, plasma gas is a mixture of argon and hydrogen, total flow rate is 45-60L / min, and the flow ratio of argon to hydrogen is (8-10):1.

[0011] The low-temperature curing step specifically involves: under a vacuum degree ≤8Pa, heating from room temperature to 130-160℃ at a rate of 5-10℃ / min, holding at that temperature for 2.5-4 hours, and then naturally cooling to room temperature.

[0012] For extreme high-temperature conditions, the ceramic reinforcing phase in the ternary composite powder is replaced with zirconium oxide, and its mass percentage is adjusted to 22-25%.

[0013] For extreme corrosive conditions, zinc powder with a mass ratio of 5-8% is added to the ternary composite powder.

[0014] For heavy dust conditions, the ceramic reinforcing phase in the ternary composite powder is replaced with tungsten carbide, and its mass ratio is adjusted to 22-25%.

[0015] When the reducer housing is a used housing, the pretreatment step of the substrate, before surface cleaning, further includes: performing defect detection on the housing and grinding and repairing the defective parts until the surface flatness error is ≤0.1mm.

[0016] The sandblasting roughening treatment uses 20-40 mesh white corundum sand, with a sandblasting pressure of 0.4-0.6 MPa and a sandblasting angle of 45-60°, to achieve a surface roughness Ra of 3.5-6.5 μm.

[0017] Compared with the prior art, the present invention has the following significant advantages: This invention employs a ternary composite coating material system. The metal matrix ensures the toughness of the coating and its compatibility with the substrate, the ceramic reinforcing phase enhances the hardness and wear resistance of the coating, and the solid lubricating phase achieves self-lubricating function. Combined with the biomimetic papillary wear-resistant structure on the surface, the three work synergistically to improve the bonding strength and microhardness of the coating.

[0018] This invention employs a low-temperature composite process, with the entire preparation temperature controlled between 120 and 180°C, which is far lower than the temperatures of existing laser cladding and conventional thermal spraying processes. This effectively avoids thermal deformation and cracking of the gearbox housing made of materials such as cast iron, cast steel, and aluminum alloy, and is suitable for gearbox housings made of various materials.

[0019] The biomimetic papillary wear-resistant structure designed in this invention can significantly reduce the coefficient of friction of the coating surface, improve wear resistance and anti-fouling ability, and enhance the heat dissipation performance of the coating, thus solving the problem of imbalance between wear resistance and lubrication performance of existing coatings.

[0020] This invention can achieve customized adaptation to extreme working conditions such as extreme high temperature, extreme corrosion, and heavy dust by adjusting the component ratio of the composite powder. At the same time, by adding defect detection and grinding repair steps, it can be adapted to the remanufacturing and repair of waste gearbox housings, realizing "new use of old housings", reducing production costs, reducing resource waste, and conforming to the concept of green manufacturing.

[0021] The low-temperature plasma spraying equipment used in this invention is mature, the process parameters are easy to control, and it can be used with a robotic arm to achieve automated spraying of complex curved surfaces. It has high production efficiency, is easy to achieve mass production, and has significant economic benefits. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the reducer housing of the present invention; Figure 2 This is a schematic diagram of the metal substrate cladding biomimetic papillary wear-resistant structure of the present invention; Figure 3 This is a schematic diagram of the biomimetic papillary structure design of the present invention; Figure 4This is a scanning electron microscope image of the biomimetic papilla of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Upper housing; 2. Lower housing; 3. Outer metal substrate; 4. Bionic nipple wear-resistant structure; 41. Bionic nipple; 5. Ternary composite coating. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] A method for preparing a wear-resistant coating for a speed reducer housing includes the following steps: Substrate pretreatment: First, the substrate of the reducer housing is cleaned: Acetone ultrasonic cleaning is performed for 15-25 minutes to remove surface oil, rust, welding slag, and other impurities. After cleaning, it is dried with compressed air to ensure no moisture or impurities remain on the surface. Then, sandblasting is performed: 20-40 mesh white corundum abrasive is used, with the sandblasting pressure controlled at 0.4-0.6 MPa and the sandblasting angle at 45-60°, until the substrate surface reaches Sa2.5 rust removal standard, and the surface roughness is controlled at Ra3.5-6.5 μm. Sandblasting significantly increases the specific surface area and roughness of the substrate surface, enhancing the mechanical adhesion between the coating and the substrate.

[0026] For the remanufacturing and repair of used gearbox housings, defect detection and grinding repair steps are required before surface cleaning: ultrasonic flaw detection is used to detect cracks, dents and other defects in the worn parts of the housing, and the defective parts are ground and repaired to ensure that the surface flatness error of the worn parts is ≤0.1mm before subsequent cleaning and sandblasting.

[0027] Ternary composite coating material configuration: Weigh the raw materials according to the following mass percentages: 65-75% metal matrix, 18-25% ceramic reinforcing phase, and 3-7% solid lubricating phase. The metal matrix is ​​selected from Ni60 alloy or NiCrBSi alloy powder with a particle size of 50-150 μm, which possesses excellent toughness and compatibility with the substrate. As the metal matrix for the coating, it ensures the overall toughness and bonding performance of the coating. The ceramic reinforcing phase is selected from nano-Al2O3 or tungsten carbide, which has high hardness and wear resistance, significantly improving the wear resistance of the coating. To enhance the compatibility between the ceramic reinforcing phase and the metal matrix, the ceramic reinforcing phase needs to undergo surface modification treatment with a silane coupling agent. The specific process is as follows: add the ceramic reinforcing phase to a 1.5-3% (w / w) silane coupling agent ethanol solution, ultrasonically disperse for 50 min, and dry at 85-100℃ to constant weight before use. The solid lubricating phase is selected from graphene or MoS2, which can reduce the coefficient of friction of the coating, achieve self-lubricating function, and solve the problem of imbalance between wear resistance and lubrication performance.

[0028] The weighed and processed raw materials were placed in a ball mill, with ethanol as the dispersion medium, a ball-to-material ratio of 10:1, a ball milling speed of 250 r / min, and a ball milling time of 5 h. After ball milling, the powder was dried at 85-100℃ to constant weight and passed through a 300-mesh sieve to obtain a uniformly mixed ternary composite powder.

[0029] For different extreme working conditions, the component ratio of the composite powder can be adjusted. (1) Extreme high temperature working conditions (160~220℃): Replace the ceramic reinforcing phase with zirconium oxide, and adjust the mass ratio to 22~25%. Zirconia has excellent high temperature stability and heat insulation performance, which can improve the high temperature wear resistance of the coating. (2) Extreme corrosion working conditions (such as marine salt spray, chemical corrosion environment): Add 5~8% zinc powder to the composite powder. Zinc powder can form sacrificial anode protection and improve the corrosion resistance of the coating. (3) Heavy dust working conditions (such as mining machinery): Replace the ceramic reinforcing phase with tungsten carbide, and adjust the mass ratio to 22~25%. Tungsten carbide has higher hardness and impact wear resistance, which can meet the wear requirements of heavy dust environment.

[0030] Design and fabrication of biomimetic papillary wear-resistant structure: The Namib Desert Beetle faces the world's harshest abrasive wear environment. Its wear-resistant protruding biological structure on its body surface significantly reduces the contact area with sand particles. Inspired by this, this invention designs a biomimetic papillary wear-resistant structure. The structure has a mushroom-shaped papillary form (bottom diameter 200μm, top diameter 400μm, height 400μm). This structure can not only significantly reduce the surface friction coefficient, improve wear resistance and anti-fouling ability, but also enhance the heat dissipation performance of the coating. At the same time, the unique protruding shape can also strengthen the bonding strength between the coating and the metal substrate.

[0031] The specific fabrication process of this biomimetic structure is as follows: A laser scanning path (matrix scanning, scanning interval 30~50μm) is designed based on the distribution requirements of mushroom-shaped papillae. The mushroom-shaped structure is formed by controlling the laser cladding process parameters, with a laser power of 2200W, a spot diameter of 0.2mm, a scanning speed of 1000mm / min, and a powder feed rate of 10g / min, ultimately forming a biomimetic papillae wear-resistant structure with a papillae spacing of 400μm. This mushroom-shaped biomimetic structure not only significantly reduces the surface friction coefficient, improves wear resistance and anti-fouling ability, and enhances the heat dissipation performance of the coating, but its unique protruding shape also strengthens the bonding strength between the coating and the metal substrate.

[0032] Low-temperature composite spraying: The prepared ternary composite powder is fed into the powder feeder of a low-temperature plasma spraying equipment. The spraying parameters are adjusted as follows: spraying power 45kW, spraying distance 120~150mm, powder feed rate 26g / min, and plasma gas is a mixture of argon and hydrogen with a total flow rate of 50L / min (argon:hydrogen = 10:1). During the spraying process, the substrate temperature is controlled to ≤180℃ using a cooling device to prevent thermal deformation. The composite powder is then sprayed onto the pretreated surface of the reducer housing to form an initial coating layer with a thickness controlled between 200~500μm, which is adjusted according to application requirements.

[0033] Low temperature curing: The gearbox housing with the initial coating layer is placed in a vacuum curing oven and cured at low temperature using a stepped heating method: the temperature is increased from room temperature to 130~160℃ at a rate of 10℃ / min, held at this temperature for 3 hours under a vacuum degree ≤8Pa, and then allowed to cool naturally to room temperature. Vacuum low-temperature curing can promote the interfacial reaction between the coating and the substrate, enhance the adhesion between the coating and the substrate, and at the same time remove residual gases inside the coating, reduce the porosity of the coating, and improve the density and stability of the coating.

[0034] Post-processing: The cured coating undergoes surface finishing: burrs and excess coating are removed from the coating surface using precision grinding or polishing to ensure a surface flatness error ≤0.05mm and a coating thickness uniformity error ≤±5μm. After finishing, the coating surface is cleaned to obtain the final ternary composite wear-resistant coating with a biomimetic papillary wear-resistant structure.

[0035] This invention first clarifies that the design of the biomimetic papilla 41 is based on biomimetic proportions and process constraints. The biomimetic papilla 41 in each embodiment is designed and fabricated using the same equation, and its structural design method can be expressed by equations. The core geometric parameters of the biomimetic papilla are as follows: d 1: Diameter of the cylindrical segment at the base of the mastoid process (reference parameter); d 2: The maximum width of the umbrella-shaped segment at the top of the mastoid process; H Total height of the mastoid process; h 1: Height of the cylindrical segment at the base of the mastoid process; h 2: Height of the umbrella-shaped segment at the top of the mastoid process; R 1: The radius of the transition fillet between the bottom cylindrical section and the top umbrella-shaped section; R 2: The outer radius of the top umbrella-shaped segment; s The distance between the centers of adjacent mastoid processes.

[0036] Based on the size ratio of the papillae on the surface of the Namib desert beetle, through "benchmark parameters" d 1” Derive all structural dimensions: d 2= d 1× k 1 (1) k 1 represents the biomimetic width magnification factor, with a value range of 1.2 ≤ k 1≤1.5, in the figure d When 1=0.2 d 2 = 0.4, corresponding to k 1=2, which can be adjusted according to wear resistance requirements in actual processes; H = d 1× k twenty two) k 2 is the biomimetic aspect ratio coefficient, with a value range of 1.0 ≤ k 2≤1.5, matching the short, stout, and wear-resistant structural characteristics of beetle papillae; h 1= R 1= d 1× k 3 (3) k 3 represents the transition fillet factor, with a value range of 0.4 ≤ k 3≤0.5, in the figure d When 1=0.2 R 1 = 0.08, corresponding to k 3 = 0.4, ensuring a smooth structural transition; h 2= Hh 1 (4) R 2=2 d 2 (5) The above equations allow for the adjustment of baseline parameters based on different operating conditions (normal / heavy load / corrosion). d 1 and proportionality coefficient k 1. k 2. k 3. Achieve quantitative and repeatable design of biomimetic papillae.

[0037] Example 1: Preparation of coating for reducer housing under normal operating conditions This embodiment is used for surface strengthening of the cast iron reducer housing under normal operating conditions (temperature -15℃~90℃, no strong corrosion, no large amount of dust). The specific steps are as follows: S1: Reference Figure 1The reducer housing is made of cast iron and includes the main structure of the upper housing 1 and the lower housing 2. It is ultrasonically cleaned with acetone for 20 minutes to remove surface oil and impurities. After being dried with compressed air, it is sandblasted with 30-mesh white corundum sand at a sandblasting pressure of 0.5MPa and a sandblasting angle of 55° to Sa2.5 grade with a surface roughness of Ra5.0μm.

[0038] S2: Weigh out 70% Ni60 alloy powder (50-150 μm particle size), 22% nano-Al2O3, and 8% graphene by mass ratio; add nano-Al2O3 to a 2% (w / w) silane coupling agent ethanol solution, ultrasonically disperse for 45 min, and dry at 90℃ to constant weight for later use; put Ni60 alloy powder, modified nano-Al2O3, and graphene into a ball mill, use ethanol as the dispersion medium, ball-to-material ratio of 10:1, speed of 250 r / min, ball mill for 5 h, dry at 90℃ to constant weight, and pass through a 250 mesh sieve to obtain ternary composite powder.

[0039] S3: Ignore Figure 1 In the internal cavities and gaps of the gearbox housing, where the laser head's posture is restricted, laser cladding is performed only on the initial coating surface of the main area where the gaps have been filled to create a biomimetic papillary wear-resistant structure 4. The structure is as follows: Figure 2 As shown. The designed laser cladding process parameters are: laser power 2200W, spot diameter 1.0mm, scanning speed 1000mm / min, powder feed rate 10g / min, argon protection flow rate 18L / min, and interlayer temperature control ≤100℃. A dot-matrix scanning path (scanning spacing 40μm) is used, and multiple layers are superimposed to form mushroom-shaped papillae (bottom diameter 32μm, top diameter 28μm, height 12μm) on the coating surface. The morphology of the prepared papillae is similar to... Figure 4 Scanning electron microscope Figure 1 To.

[0040] S4: Feed the above composite powder into a low-temperature plasma spraying equipment with a spraying power of 42kW, a spraying distance of 140mm, a powder feed rate of 25g / min, an argon flow rate of 48L / min, and a hydrogen flow rate of 5L / min. Adjust the spray gun head angle to 50° and use a reciprocating spraying path to ensure the coating is sprayed into the pre-set gap of the protrusion; control the substrate temperature to ≤180℃. Figure 1 The upper housing 1 and lower housing 2 of the gearbox housing are sprayed with a primary coating layer to form the initial coating (corresponding to...). Figure 3 The ternary composite coating 5), with a thickness of 420~500μm, completely covers the substrate and fills the gaps between the papillae.

[0041] S5: Place the outer shell into a vacuum curing oven, heat it to 150°C at a rate of 8°C / min, maintain the vacuum at 5Pa, keep it at that temperature for 3 hours, and then let it cool naturally to room temperature.

[0042] S6: Precision grinding is used to remove burrs from the coating surface, ensuring that the coating thickness uniformity error is ≤ ±5μm and the surface flatness error is ≤ 0.05mm. After cleaning, the final coating is obtained, covering... Figure 1 The main body area of ​​the gearbox housing has Figure 2 The biomimetic papillary wear-resistant structure 4 is shown.

[0043] Example 2: Remanufacturing and Repair of Used Gearbox Housings This embodiment is used for the remanufacturing and repair of the housing of a scrap cast steel reducer used in mining machinery. The housing has localized wear and minor corrosion defects. The specific steps are as follows: S1: Reference Figure 1 Ultrasonic flaw detection was used to inspect the wear and corrosion defects of the outer casing (upper housing 1 and lower housing 2) of the waste reducer. The defective parts were ground and repaired to ensure that the surface flatness error of the worn parts was ≤0.1mm. Then, acetone ultrasonic cleaning was used for 25 minutes to remove surface oil and impurities. After drying with compressed air, sandblasting was performed with 20-mesh white corundum sand at a sandblasting pressure of 0.6MPa and a sandblasting angle of 60° to Sa2.5 grade, with a surface roughness of Ra6.2μm.

[0044] S2: Weigh out 65% NiCrBSi alloy powder (50-150μm), 25% tungsten carbide, and 10% MoS2 by mass ratio; add tungsten carbide to a 3% silane coupling agent ethanol solution, ultrasonically disperse for 60 min, and dry at 100℃ to constant weight for later use; put the NiCrBSi alloy powder, modified tungsten carbide, and MoS2 into a ball mill, use ethanol as the dispersion medium, ball-to-material ratio of 10:1, speed of 300 r / min, ball mill for 6 h, dry at 100℃ to constant weight, and pass through a 300-mesh sieve to obtain ternary composite powder.

[0045] S3: Ignore if Figure 1 In the case of a waste cast steel reducer housing, where the laser head's orientation is restricted due to internal deep cavities and gaps, laser cladding was performed only on the initial coating layer surface of the main wear repair area and surrounding main body parts where gaps had been filled to create a mushroom-shaped biomimetic papilla wear-resistant structure. The designed laser cladding process parameters were: laser power 2500W, spot diameter 1.2mm, scanning speed 800mm / min, powder feed rate 12g / min, argon protection flow rate 20L / min, and interlayer temperature control ≤100℃. A dot-matrix scanning path (scanning spacing 50μm) was used, and multiple layers were superimposed to form mushroom-shaped papillae (bottom diameter 40μm, top diameter 35μm, height 15μm) on the initial coating layer surface, achieving a morphological match. Figure 4 Electron microscopic features.

[0046] S4: Feed the composite powder into a low-temperature plasma spraying equipment with a spraying power of 45kW, a spraying distance of 120mm, a powder feed rate of 30g / min, an argon flow rate of 55L / min, and a hydrogen flow rate of 5.5L / min. Adjust the spray gun angle to 60° and use a reciprocating spraying path to ensure the coating penetrates the worn area and the pre-set gaps in the surrounding main body parts. Control the substrate temperature to ≤180℃. Spray the coating onto the worn repair area to form an initial layer, such as... Figure 3 The ternary composite coating 5, with a thickness of 320 μm, completely covers the wear repair area and fills the papillary gap.

[0047] S5: Place the outer shell into a vacuum curing oven, heat it to 160°C at a rate of 10°C / min, maintain the vacuum at 8Pa, keep it at that temperature for 4 hours, and then let it cool naturally to room temperature.

[0048] S6: Precision grinding is used to remove burrs and excess coating from the coating surface, ensuring that the coating thickness uniformity error is ≤ ±5μm and the surface flatness error is ≤ 0.05mm. After cleaning, the repaired reducer housing is obtained.

[0049] Example 3: Coating preparation for extreme marine corrosion conditions This embodiment is used for surface strengthening of the housing of an aluminum alloy gearbox for marine equipment, adapting to marine salt spray corrosion conditions. The specific steps are as follows: S1: Reference Figure 1 The reducer housing (upper housing 1 and lower housing 2) is made of aluminum alloy. It is ultrasonically cleaned with acetone for 15 minutes to remove surface oil and impurities. After being dried with compressed air, it is sandblasted with 40-mesh white corundum sand at a sandblasting pressure of 0.4 MPa and a sandblasting angle of 45° to Sa2.5 grade with a surface roughness of Ra3.8 μm.

[0050] S2: Weigh out 67% Ni60 alloy powder (50-150 μm), 20% nano Al2O3, 5% graphene, and 8% zinc powder by mass ratio; add nano Al2O3 to a 1.5% (w / w) silane coupling agent ethanol solution, ultrasonically disperse for 35 min, and dry at 85℃ to constant weight for later use; put Ni60 alloy powder, modified nano Al2O3, graphene, and zinc powder into a ball mill, use ethanol as the dispersion medium, ball-to-material ratio of 10:1, speed of 220 r / min, ball mill for 4 h, dry at 85℃ to constant weight, and pass through a 200-mesh sieve to obtain ternary composite powder.

[0051] S3: Ignore Figure 1 For the internal cavities and gaps of the outer shell, only the surface of the initial coating layer in the main body area is prepared using laser cladding. Figure 2The biomimetic papilla 4 was designed with the following settings: laser power 1800W, spot diameter 0.8mm, scanning speed 1200mm / min, powder feed rate 8g / min, argon protection flow rate 15L / min, and interlayer temperature ≤100℃; lattice scanning path (spacing 30μm); and cladding formation. Figure 3 Mushroom-shaped papillae 41 (base diameter 25 μm, top diameter 20 μm, height 8 μm), distribution density 1200 / mm², morphology similar to Figure 4 Scanning electron microscope Figure 1 To.

[0052] S4: Feed the composite powder into a low-temperature plasma spraying device with a spraying power of 38kW, a spraying distance of 160mm, a powder feed rate of 22g / min, an argon flow rate of 42L / min, and a hydrogen flow rate of 4.2L / min. Adjust the spray gun head angle to 45° and use a reciprocating spraying path to ensure the coating is sprayed into the pre-set gaps of the protrusions. Control the substrate temperature to ≤180℃. Spray to form an initial coating layer with a thickness of 150μm. This initial layer completely covers the substrate and fills the gaps between the protrusions. Figure 3 The ternary composite coating 5 shown in the figure.

[0053] S5: Place the outer shell into a vacuum curing oven, heat it to 130°C at a rate of 5°C / min, maintain the vacuum at 3Pa, keep it at that temperature for 2.5 hours, and then let it cool naturally to room temperature.

[0054] S6: Use polishing to remove burrs from the coating surface, ensuring that the coating thickness uniformity error is ≤ ±5μm and the surface flatness error is ≤ 0.05mm. The final coating is obtained after cleaning.

[0055] The above embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention. Various modifications, alterations, equivalent substitutions and improvements made by those skilled in the art within the scope of the claims should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a wear-resistant coating for a speed reducer housing, characterized in that, Includes the following steps: Substrate pretreatment: The substrate of the reducer housing is cleaned and roughened by sandblasting. Ternary composite coating material preparation: Weigh out 65-75% metal matrix, 18-25% ceramic reinforcement phase, and 3-7% solid lubricating phase according to the mass ratio, and mix them evenly to obtain ternary composite powder; wherein, the metal matrix is ​​Ni60 alloy or NiCrBSi alloy powder, the ceramic reinforcement phase is nano Al2O3 or tungsten carbide with silane coupling agent surface modification treatment, and the solid lubricating phase is graphene or MoS2. Preparation of biomimetic papillary wear-resistant structure: A mushroom-shaped biomimetic papillary wear-resistant structure is formed on the surface of a pre-treated substrate or the surface of a pre-formed coating layer by laser cladding process; Low-temperature composite spraying: Using a low-temperature plasma spraying process, ternary composite powder is sprayed onto the surface of a substrate with a biomimetic papillary wear-resistant structure to form an initial coating layer. During the spraying process, the substrate temperature is controlled to be ≤180℃. Low-temperature curing: The workpiece with the initial coating layer is placed in a vacuum environment for step-by-step temperature curing. Post-treatment: The cured coating is then repaired and cleaned.

2. The method for preparing a wear-resistant coating for a speed reducer housing according to claim 1, characterized in that, The surface modification treatment of the ceramic reinforcing phase specifically involves: adding the ceramic reinforcing phase to a 1.5-3% (w / w) silane coupling agent ethanol solution and ultrasonically dispersing it, followed by drying it at 85-100°C to constant weight.

3. The method for preparing a wear-resistant coating for a speed reducer housing according to claim 1, characterized in that, The biomimetic mastoid wear-resistant structure is mushroom-shaped, where d1 is the diameter of the cylindrical segment at the bottom of the mastoid; d2 is the maximum width of the umbrella-shaped segment at the top of the mastoid; H is the total height of the mastoid; h1 is the height of the cylindrical segment at the bottom of the mastoid; h2 is the height of the umbrella-shaped segment at the top of the mastoid; R1 is the radius of the transition fillet between the cylindrical segment at the bottom and the umbrella-shaped segment at the top; R2 is the outer radius of the umbrella-shaped segment at the top; and s is the center-to-center distance between adjacent mastoids. The diameter d1 of the cylindrical segment at the base of the mastoid process is used as the reference parameter. d2=d1×k1 k1 is the biomimetic width magnification factor, with a value range of 1.2 ≤ k1 ≤ 1.5; H=d1×k2 k2 is the biomimetic aspect ratio coefficient, with a value range of 1.0≤k2≤1.5, matching the short, sturdy, and wear-resistant structural characteristics of beetle papillae; h1=R1=d1×k3 k3 is the transition fillet factor, with a value range of 0.4≤k3≤0.5, to ensure a smooth structural transition; h2=H-h1 R2=2d2.

4. The method for preparing a wear-resistant coating for a speed reducer housing according to claim 1, characterized in that, The parameters of the low-temperature plasma spraying process are as follows: spraying power 38-45kW, spraying distance 120-160mm, powder feeding rate 22-30g / min, plasma gas is a mixture of argon and hydrogen, total flow rate is 45-60L / min, and the flow ratio of argon to hydrogen is (8-10):

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5. The method for preparing a wear-resistant coating for a speed reducer housing according to claim 1, characterized in that, The low-temperature curing step specifically involves: under a vacuum degree ≤8Pa, heating from room temperature to 130-160℃ at a rate of 5-10℃ / min, holding at that temperature for 2.5-4 hours, and then naturally cooling to room temperature.

6. The method for preparing a wear-resistant coating for a speed reducer housing according to claim 1, characterized in that, For extreme high-temperature conditions, the ceramic reinforcing phase in the ternary composite powder is replaced with zirconium oxide, and its mass percentage is adjusted to 22-25%.

7. The method for preparing a wear-resistant coating for a speed reducer housing according to claim 1, characterized in that, For extreme corrosive conditions, zinc powder with a mass ratio of 5-8% is added to the ternary composite powder.

8. The method for preparing a wear-resistant coating for a speed reducer housing according to claim 1, characterized in that, For heavy dust conditions, the ceramic reinforcing phase in the ternary composite powder is replaced with tungsten carbide, and its mass ratio is adjusted to 22-25%.

9. The method for preparing a wear-resistant coating for a speed reducer housing according to claim 1, characterized in that, When the reducer housing is a used housing, the pretreatment step of the substrate, before surface cleaning, also includes: performing defect detection on the housing and grinding and repairing the defective parts until the surface flatness error is ≤0.1mm.

10. The method for preparing a wear-resistant coating for a speed reducer housing according to claim 1, characterized in that, The sandblasting roughening treatment uses 20-40 mesh white corundum sand, with a sandblasting pressure of 0.4-0.6 MPa and a sandblasting angle of 45-60°, to achieve a surface roughness Ra of 3.5-6.5 μm.

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