Porous oil-containing hydroxyapatite knuckle bearing surface preparation method based on electrochemical deposition

Abstract

The invention discloses a porous oil-containing hydroxyapatite knuckle bearing surface preparation method based on electrochemical deposition, which is combined with surface texture design to improve the binding force of porous hydroxyapatite and is applied to a composite surface of a titanium alloy knuckle bearing. The method is specifically implemented according to the following steps that 1, the titanium alloy knuckle bearing micro-arc coating is prepared; step 2, surface texture design and laser etching; 3, hydroxyapatite is electrochemically deposited to form a porous liquid storage coating structure, and a hydroxyapatite composite lubricating interface is prepared on the outer surface of the inner ring of the knuckle bearing. The composite surface can improve the lubricating performance, the wear resistance and the storage and conveying capacity of lubricating liquid, and is particularly suitable for a knuckle bearing working under the conditions of high load, high speed and extreme temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical engineering, and in particular relates to a method for preparing the surface of a porous oil-containing hydroxyapatite joint bearing based on electrochemical deposition. Background Art

[0002] Titanium alloy spherical plain bearings are widely used in the aerospace industry, enduring high loads, high speeds, and extreme temperatures. Under these conditions, traditional liquid lubrication methods face challenges such as evaporation, loss, and "creep flow," leading to reduced lubricant flow, increased friction, accelerated wear, and even equipment failure. To address these challenges, researchers are exploring new methods to improve lubricant stability. While high-performance lubricants perform well in specific environments, they still face challenges such as evaporation loss and high-temperature creep.

[0003] The patent (US11982313B2) machines multiple circumferential lubrication grooves on the outer surface of the inner ring of a spherical plain bearing. Simultaneously, it forms an interfacial sliding joint between the concave bearing surface of the inner spherical surface of the outer ring and the convex bearing surface of the outer spherical surface of the inner ring. Lubricant loss is limited by lubricating seals, thereby enhancing lubrication coverage, improving the dynamic performance of the bearing, and extending its service life. While this method improves lubrication coverage to a certain extent, it still relies on the fluidity and sealing effect of the lubricant, and it is difficult to completely solve the problems of lubricant volatilization and loss, as well as the instability of the lubricating film in high-temperature environments. Furthermore, the patent fails to fully utilize the liquid storage capacity of the material surface, resulting in limited lubrication continuity. The patent (CN107387553B) creates a surface texture on the outer spherical surface of the bearing inner ring and uses a friction pre-filling technique to fill the texture with a polytetrafluoroethylene (PTFE)-based self-lubricating material. Furthermore, a fabric self-lubricating material liner is adhered to the inner spherical surface of the bearing outer ring. This optimizes the friction interface material configuration, improves the bearing's lubrication and wear resistance, reduces the coefficient of friction, and significantly extends the service life of the self-lubricating spherical plain bearing. However, the PTFE filler material may still experience creep, wear, and aging issues in high-temperature and high-load environments, affecting long-term use. Furthermore, the texture depth and shape of this patent are limited, making it difficult to ensure the accuracy and consistency of its processing method. Furthermore, its adaptability to complex surfaces is limited, making it difficult to meet the requirements of use in extreme working conditions.

[0004] Porous media, due to their large specific surface area and rich pore structure, can effectively store and transport lubricants, solving the problem of loss. Combining the design of surface texture and porous structure can enhance the stability of the lubricating oil film, improve the efficiency of lubricating fluid transportation, and extend the service life of the equipment. The basic principle of preparing hydroxyapatite by electrochemical deposition is a preparation method in which a chemical reaction occurs on the electrode surface under the action of an external electric field to form a hydroxyapatite coating. The porous hydroxyapatite structure based on electrochemical deposition provides ideal conditions for the storage and transportation of lubricants due to its excellent lipophilicity and high porosity, and has broad application prospects, especially in the lubrication field of high-end mechanical equipment such as spherical bearings. Summary of the Invention

[0005] The present invention aims to provide a method for preparing porous, oil-containing hydroxyapatite spherical bearing surfaces based on electrochemical deposition. This method, combined with surface texture design, enhances the bonding strength of the porous hydroxyapatite and can be applied to the composite surface of titanium alloy spherical bearings. This composite surface improves lubrication performance, wear resistance, and lubricant storage and transport capabilities, making it particularly suitable for spherical bearings operating under high loads, high speeds, and extreme temperatures.

[0006] The technical solution adopted by the present invention is a method for preparing a porous oil-containing hydroxyapatite spherical bearing surface based on electrochemical deposition, which is specifically implemented according to the following steps:

[0007] Step 1, preparation of micro-arc coating of titanium alloy spherical plain bearing;

[0008] Step 2: surface texture design and laser etching;

[0009] Step 3: Electrochemically deposit hydroxyapatite to form a porous liquid storage coating structure, and prepare a hydroxyapatite composite lubrication interface on the outer surface of the inner ring of the spherical plain bearing.

[0010] The present invention is also characterized in that:

[0011] Step 1 is implemented as follows:

[0012] Step 1.1: Pre-treat the inner ring of the titanium alloy spherical plain bearing by ultrasonically cleaning it with anhydrous ethanol or acetone to remove oil, dust, and other contaminants on the surface. Rinse it with deionized water and dry it. Pickle it with a dilute nitric acid solution to remove the natural oxide layer on the surface. Rinse it with deionized water after pickling and neutralize it with an alkaline solution. Rinse it again and dry it to keep the workpiece surface clean and free of impurities.

[0013] Step 1.2: Using high-voltage electrostatic spraying equipment, a polytetrafluoroethylene protective coating having a mass concentration of 5-10 wt% is evenly sprayed onto the inner surface of the inner ring of the spherical plain bearing. The protective coating is evenly sprayed onto the inner surface of the inner ring of the titanium alloy spherical plain bearing, thereby achieving a uniform and dense protective layer of 0.2 to 0.5 mm to isolate the erosion of chemical media during subsequent micro-arc oxidation and electrochemical deposition processes. After spraying, the inner ring of the titanium alloy spherical plain bearing is allowed to stand at room temperature to dry and solidify.

[0014] Step 1.3, preparing an electrolyte: weighing 0.12-0.18wt% calcium nitrate, 0.50-0.70wt% ammonium dihydrogen phosphate, 0.20-0.30wt% sodium hydroxide, and the remainder deionized water, such that the sum of the mass percentages of the above components is 100%, to adjust the solution pH to 4.2-7.0, then stir and mix thoroughly until a uniform electrolyte is formed, and let it stand for use;

[0015] Step 1.4: Place the inner ring of the titanium alloy spherical plain bearing cleaned in step 1.2 into the electrolyte prepared in step 1.3, start the micro-arc oxidation equipment, select the constant current mode, and ensure that the oxidation process is stable;

[0016] Step 1.5: After the treatment is completed, remove the inner ring of the titanium alloy spherical plain bearing from the electrolytic tank, rinse it with deionized water to remove the residual electrolyte on the surface, dry it naturally or use hot air to form a micro-arc oxidation surface on the outer surface of the inner ring of the titanium alloy spherical plain bearing.

[0017] In step 1.2, set the spraying distance to 15-30 cm and the spraying pressure to 0.2-0.4 MPa, let it dry for 10-20 minutes, and then transfer it to an oven at 80-120°C to cure for 30-60 minutes;

[0018] In step 1.4, the frequency is set to 500-700 Hz, the pulse width is set to 120-180 μs, and the time is set to 10-30 minutes.

[0019] Step 2 is implemented as follows:

[0020] Step 2.1. Design a pitcher plant-like composite lubrication track on the outer surface of the inner ring of the spherical plain bearing. The pitcher plant-like composite lubrication track is arranged axially. The main body consists of a central linear guide track and multiple divergent branch tracks on both sides. The overall shape is "fishbone" or "swallowtail" and has bidirectional wetting guidance and central liquid collection functions. The linear track plays a leading role in transmission, while the divergent tracks achieve drainage, uniform distribution, and edge locking control of the droplets.

[0021] Step 2.2: Laser etching is performed on the outer surface of the inner ring of the titanium alloy spherical plain bearing. After laser etching, the workpiece is immediately immersed in anhydrous ethanol for ultrasonic cleaning to remove residual laser etching products on the surface.

[0022] Step 2.3: Polish the inner ring of the spherical plain bearing, and then perform a secondary ultrasonic cleaning using a mixed solution of alcohol and acetone with a volume ratio of 1 to 2:1; after completion, dry it to finally form a uniform and dense micro-arc oxidation-textured surface on the surface of the inner ring of the titanium alloy spherical plain bearing.

[0023] The specific texture parameters of the pitcher plant-like composite lubrication track in step 2.1 are summarized as follows: the pitcher plant-linear track spacing b is set to 0.3-0.8 mm; the divergent track width W2 is 1.0-1.5 mm; the total width W of the composite wetting track is 1.5-3.5 mm; the total length L of the pitcher plant-like track is 5-7 mm; at the same time, the texture width d is 50-200 μm, the texture depth h is 10-50 μm; the texture angle α is 30°-60°, and a divergence angle Dα of 2°-5° is introduced.

[0024] In step 2.2, the laser power is 20-25 W, the frequency is 20-40 KHz, the pulse width is 50-150 ns, the processing speed is 20-40 mm / s, the number of scans is 1-2 times, and the ultrasonic cleaning time is 10-20 min.

[0025] In step 2.3, the rotation speed is set to 20-40 rpm, the processing time is 20-30 minutes, the cleaning time is 10-20 minutes, the drying temperature is 80-100°C, and the drying time is 15-30 minutes.

[0026] Step 3 is implemented as follows:

[0027] Step 3.1, select anhydrous CaCl2, NH4H2PO4, and NaCl as electrolytes to prepare an electrolyte, wherein the concentration of anhydrous CaCl2 is 0.23-0.26 mol / L, the concentration of NH4H2PO4 is 0.13-0.15 mol / L, and the concentration of NaCl is 0.095-0.105 mol / L, so that the n(Ca2+):n(PO4 3- ) is 1.6-1.75 and pH is 4.2-7.0;

[0028] Step 3.2: Electrochemically deposit a hydroxyapatite coating on the outer surface of the inner ring of the micro-arc oxidation-textured spherical plain bearing obtained in step 2.3. The electrolyte prepared in step 3.1 is added to a container in a predetermined amount, with the volume of the electrolyte accounting for 70%-80% of the total volume of the container. In the container, the titanium alloy bearing serves as the cathode and the graphite plate serves as the anode, with the distance between the two electrodes maintained at 1-5 cm.

[0029] Step 3.3: Place the container containing the electrolyte in step 3.2 into a heat-collecting constant-temperature heater. Maintain a constant temperature during the electrochemical reaction using a constant-temperature oil bath. Place a rotor in the reaction container for magnetic stirring at a speed of 500-1000 rpm to ensure that the chemicals in the electrolyte are evenly dispersed during the reaction. Place the titanium alloy spherical bearing and the graphite plate in a pure copper semi-enclosed electrode holder and connect them to the negative and positive electrodes of a DC regulated power supply, respectively.

[0030] Step 3.4: Perform electrochemical deposition using a constant voltage method, set the DC regulated voltage to 2-4V, the deposition temperature to 40-80°C, start deposition and time the deposition after preparation, and the deposition time is 15-40 minutes;

[0031] Step 3.5, let the inner surface of the titanium alloy spherical bearing after electrochemical deposition in step 3.4 stand and dry naturally, then heat it to a temperature of 600-800°C and keep it warm for 2-3 hours, use alcohol to ultrasonically clean the inner surface of the inner ring of the titanium alloy spherical bearing, the ultrasonic cleaning frequency is 40-60kHz, the ultrasonic cleaning temperature is 30-50°C, and the ultrasonic cleaning time is 10-20min. After cleaning, take out the inner ring of the titanium alloy spherical bearing, immediately rinse it with deionized water to remove the residual cleaning liquid, and blow it dry with a clean air flow to finally obtain a micro-arc oxidation-texture-hydroxyapatite composite surface on the inner ring of the titanium alloy spherical bearing.

[0032] The beneficial effect of the present invention is that it proposes a method for preparing the surface of porous oil-containing hydroxyapatite spherical bearings based on electrochemical deposition, which has the advantages of synergistic enhancement of structure and function, significant improvement of lubrication performance, and simple and controllable preparation process compared to the existing technology. By constructing a composite structure of a dense binding layer and a porous liquid storage layer, the oil adsorption and sustained release capabilities of the coating are effectively improved; the bionic pitcher plant-divergent lubrication track design is adopted to achieve directional spreading and stable locking of the lubricating oil on the interface; at the same time, the deposition parameters are highly adjustable, and the pore structure, Ca / P ratio and crystallinity of the coating can be accurately controlled to meet the lubrication requirements under complex working conditions. The method has good process adaptability and is suitable for the construction of lubricating surfaces of complex curved components such as spherical bearings, and has good prospects for application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a cross-sectional view of a spherical joint bearing, which is mainly composed of an inner ring and an outer ring. The outer surface of the inner ring is in friction contact with the inner surface of the outer ring to form a sliding contact surface. This patent prepares a micro-arc oxidation-texture-hydroxyapatite composite surface on the outer surface of the inner ring of the spherical joint bearing.

[0034] Figure 2 This is a schematic diagram of the Nepenthes-divergent composite orbital structure;

[0035] Figure 3It is a flow chart of the preparation of porous liquid reservoir surface of hydroxyapatite by electrochemical deposition;

[0036] Figure 4 (a) is the SEM macroscopic surface of the micro-arc oxidation-texture-hydroxyapatite surface coating;

[0037] Figure 4 (b) is the SEM micromorphology of the micro-arc oxidation-texture-hydroxyapatite surface coating;

[0038] Figure 4 (c) Figure 4 (d) Element distribution of titanium matrix and hydroxyapatite coating, respectively;

[0039] Figure 5 This is a diagram of the process of lubricating oil impacting a composite surface;

[0040] Figure 6 This is a diagram of the lubricating oil spreading flow process. DETAILED DESCRIPTION

[0041] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] The method for preparing the surface of a porous oil-containing hydroxyapatite spherical bearing based on electrochemical deposition of the present invention is specifically implemented according to the following steps:

[0043] Step 1, preparation of micro-arc coating of titanium alloy spherical plain bearing;

[0044] Step 1 is implemented as follows:

[0045] Step 1.1: Pre-treat the inner ring of the titanium alloy spherical plain bearing by ultrasonically cleaning it with anhydrous ethanol or acetone to remove oil, dust, and other contaminants on the surface. Rinse it with deionized water and dry it. Pickle it with a dilute nitric acid solution to remove the natural oxide layer on the surface. Rinse it with deionized water after pickling and neutralize it with an alkaline solution. Rinse it again and dry it to keep the workpiece surface clean and free of impurities.

[0046] Step 1.2: Using high-voltage electrostatic spraying equipment, a polytetrafluoroethylene protective coating with a mass concentration of 5-10wt% is evenly sprayed on the inner surface of the inner ring of the spherical bearing, and the protective coating is evenly sprayed on the inner surface of the inner ring of the titanium alloy spherical bearing, thereby achieving a uniform and dense protective layer of 0.2 to 0.5mm to isolate the erosion of chemical media during subsequent micro-arc oxidation and electrochemical deposition. After spraying, the inner ring of the titanium alloy spherical bearing is allowed to stand and dry at room temperature and solidify. In step 1.2, the spraying distance is set to 15-30cm, the spraying pressure is set to 0.2-0.4MPa, and the mixture is allowed to stand and dry for 10-20min, and then transferred to an oven at 80-120°C for curing for 30-60min.

[0047] Step 1.3, prepare an electrolyte: weigh 0.12-0.18wt% of calcium nitrate (Ca(NO3)2·4H2O), 0.50-0.70wt% of ammonium dihydrogen phosphate ((NH4)H2PO4), 0.20-0.30wt% of sodium hydroxide (NaOH), and the remainder deionized water, by mass fraction, so that the sum of the mass percentages of the above components is 100%, and adjust the solution pH to 4.2-7.0, then stir and mix thoroughly until a uniform electrolyte is formed, and let it stand for use;

[0048] Step 1.4: Place the inner ring of the titanium alloy spherical plain bearing cleaned in step 1.2 into the electrolyte prepared in step 1.3, start the micro-arc oxidation equipment, select the constant current mode, and ensure that the oxidation process is stable; in step 1.4, set the frequency to 500-700 Hz, the pulse width to 120-180 μs, and the time to 10-30 min.

[0049] Step 1.5: After the treatment is completed, remove the inner ring of the titanium alloy spherical plain bearing from the electrolytic tank, rinse it with deionized water to remove the residual electrolyte on the surface, dry it naturally or use hot air to form a micro-arc oxidation surface on the outer surface of the inner ring of the titanium alloy spherical plain bearing.

[0050] Step 2: surface texture design and laser etching;

[0051] Step 2 is implemented as follows:

[0052] Step 2.1, inspired by the Nepenthes-divergent composite wetting track, a Nepenthes-like composite lubrication track is designed on the outer surface of the inner ring of the spherical bearing (such as Figure 1 、 Figure 2 As shown in the figure, the pitcher plant-like composite lubrication track is arranged axially as a whole. The main body consists of a central linear guide track and multiple divergent branch tracks on both sides. The overall shape is "fishbone-shaped" or "swallowtail-shaped" and has bidirectional wetting guidance and central liquid collection functions. The linear track plays a leading role in transmission, while the divergent track realizes the drainage, uniform distribution and edge locking control of the droplets.

[0053] The specific texture parameters of the pitcher plant-like composite lubrication track in step 2.1 are summarized as follows: the pitcher plant-linear track spacing b is set to 0.3-0.8 mm; the divergent track width W2 is 1.0-1.5 mm; the total width W of the composite wetting track is 1.5-3.5 mm; the total length L of the pitcher plant-like track is 5-7 mm; at the same time, the texture width d is 50-200 μm, the texture depth h is 10-50 μm; the texture angle α is 30°-60°, and a divergence angle Dα of 2°-5° is introduced to achieve efficient directional spreading and driving effect of droplets on the track.

[0054] Step 2.2: Laser etching is performed on the outer surface of the inner ring of the titanium alloy spherical plain bearing. After laser etching, the workpiece is immediately immersed in anhydrous ethanol for ultrasonic cleaning to remove residual laser etching products on the surface.

[0055] In step 2.2, the laser power is 20-25 W, the frequency is 20-40 KHz, the pulse width is 50-150 ns, the processing speed is 20-40 mm / s, the number of scans is 1-2 times, and the ultrasonic cleaning time is 10-20 min.

[0056] Step 2.3: Polish the inner ring of the spherical plain bearing, and then perform a secondary ultrasonic cleaning using a mixed solution of alcohol and acetone with a volume ratio of 1 to 2:1; after completion, dry it to finally form a uniform and dense micro-arc oxidation-textured surface on the surface of the inner ring of the titanium alloy spherical plain bearing.

[0057] In step 2.3, the rotation speed is set to 20-40 rpm, the processing time is 20-30 minutes, the cleaning time is 10-20 minutes, the drying temperature is 80-100°C, and the drying time is 15-30 minutes.

[0058] Step 3: Electrochemically deposit hydroxyapatite to form a porous liquid storage coating structure, and prepare a hydroxyapatite composite lubrication interface on the outer surface of the inner ring of the spherical plain bearing.

[0059] Step 3 is implemented as follows:

[0060] Step 3.1, select anhydrous CaCl2, NH4H2PO4, and NaCl as electrolytes to prepare an electrolyte, wherein the concentration of anhydrous CaCl2 is 0.23-0.26 mol / L, the concentration of NH4H2PO4 is 0.13-0.15 mol / L, and the concentration of NaCl is 0.095-0.105 mol / L, so that the n(Ca2+):n(PO4 3- ) is 1.6-1.75 and pH is 4.2-7.0;

[0061] Step 3.2: Electrochemically deposit a hydroxyapatite coating on the outer surface of the inner ring of the micro-arc oxidation-textured spherical plain bearing obtained in step 2.3. The processing process is as follows: Figure 3 Add the electrolyte prepared in step 3.1 into the container in a quantitative manner, with the volume of the electrolyte accounting for 70%-80% of the total capacity of the container. In the container, use the titanium alloy bearing as the cathode and the graphite plate as the anode, and maintain a distance of 1-5 cm between the two electrodes.

[0062] Step 3.3: Place the container containing the electrolyte in step 3.2 into a heat-collecting constant-temperature heater. Maintain a constant temperature during the electrochemical reaction using a constant-temperature oil bath. Place a rotor in the reaction container for magnetic stirring at a speed of 500-1000 rpm to ensure that the chemicals in the electrolyte are evenly dispersed during the reaction. Place the titanium alloy spherical bearing and the graphite plate in a pure copper semi-enclosed electrode holder and connect them to the negative and positive electrodes of a DC regulated power supply, respectively.

[0063] Step 3.4: Perform electrochemical deposition using a constant voltage method, set the DC regulated voltage to 2-4V, the deposition temperature to 40-80°C, start deposition and time the deposition after preparation, and the deposition time is 15-40 minutes;

[0064] Step 3.5, let the inner surface of the titanium alloy spherical bearing after electrochemical deposition in step 3.4 stand and dry naturally, then place it in a box-type resistance furnace for heating, the heating temperature is 600-800℃, and keep warm for 2-3h, use alcohol to ultrasonically clean the inner surface of the inner ring of the titanium alloy spherical bearing, the ultrasonic cleaning frequency is 40-60kHz, the ultrasonic cleaning temperature is 30-50℃, and the ultrasonic cleaning time is 10-20min. After cleaning, take out the inner ring of the titanium alloy spherical bearing, immediately rinse it with deionized water to remove the residual cleaning liquid, and blow it dry with clean air flow to finally obtain a micro-arc oxidation-texture-hydroxyapatite composite surface on the inner ring of the titanium alloy spherical bearing.

[0065] Example 1

[0066] The method for preparing the surface of a porous oil-containing hydroxyapatite spherical bearing based on electrochemical deposition of the present invention is specifically implemented according to the following steps:

[0067] Step 1, preparation of micro-arc coating of titanium alloy spherical plain bearing;

[0068] Step 2: surface texture design and laser etching;

[0069] Step 3: Electrochemically deposit hydroxyapatite to form a porous liquid storage coating structure, and prepare a hydroxyapatite composite lubrication interface on the outer surface of the inner ring of the spherical plain bearing.

[0070] Example 2

[0071] The method for preparing the surface of a porous oil-containing hydroxyapatite spherical bearing based on electrochemical deposition of the present invention is specifically implemented according to the following steps:

[0072] Step 1, preparation of micro-arc coating of titanium alloy spherical plain bearing;

[0073] Step 1 is implemented as follows:

[0074] Step 1.1: Pre-treat the inner ring of the titanium alloy spherical plain bearing by ultrasonically cleaning it with anhydrous ethanol or acetone to remove oil, dust, and other contaminants on the surface. Rinse it with deionized water and dry it. Pickle it with a dilute nitric acid solution to remove the natural oxide layer on the surface. Rinse it with deionized water after pickling and neutralize it with an alkaline solution. Rinse it again and dry it to keep the workpiece surface clean and free of impurities.

[0075] Step 1.2: Using high-voltage electrostatic spraying equipment, a polytetrafluoroethylene protective coating having a mass concentration of 5-10 wt% is evenly sprayed onto the inner surface of the inner ring of the spherical plain bearing. The protective coating is evenly sprayed onto the inner surface of the inner ring of the titanium alloy spherical plain bearing, thereby achieving a uniform and dense protective layer of 0.2 to 0.5 mm to isolate the erosion of chemical media during subsequent micro-arc oxidation and electrochemical deposition processes. After spraying, the inner ring of the titanium alloy spherical plain bearing is allowed to stand at room temperature to dry and solidify.

[0076] Step 1.3, preparing an electrolyte: weighing 0.12-0.18wt% calcium nitrate, 0.50-0.70wt% ammonium dihydrogen phosphate, 0.20-0.30wt% sodium hydroxide, and the remainder deionized water, such that the sum of the mass percentages of the above components is 100%, to adjust the solution pH to 4.2-7.0, then stir and mix thoroughly until a uniform electrolyte is formed, and let it stand for use;

[0077] Step 1.4: Place the inner ring of the titanium alloy spherical plain bearing cleaned in step 1.2 into the electrolyte prepared in step 1.3, start the micro-arc oxidation equipment, select the constant current mode, and ensure that the oxidation process is stable;

[0078] Step 1.5: After the treatment is completed, remove the inner ring of the titanium alloy spherical plain bearing from the electrolytic tank, rinse it with deionized water to remove the residual electrolyte on the surface, dry it naturally or use hot air to form a micro-arc oxidation surface on the outer surface of the inner ring of the titanium alloy spherical plain bearing.

[0079] Step 2: surface texture design and laser etching;

[0080] Step 2 is implemented as follows:

[0081] Step 2.1, inspired by the Nepenthes-divergent composite wetting track, a Nepenthes-like composite lubrication track is designed on the outer surface of the inner ring of the spherical bearing (such as Figure 1 、 Figure 2 As shown in the figure, the pitcher plant-like composite lubrication track is arranged axially as a whole. The main body consists of a central linear guide track and multiple divergent branch tracks on both sides. The overall shape is "fishbone-shaped" or "swallowtail-shaped" and has bidirectional wetting guidance and central liquid collection functions. The linear track plays a leading role in transmission, while the divergent track realizes the drainage, uniform distribution and edge locking control of the droplets.

[0082] Step 2.2: Laser etching is performed on the outer surface of the inner ring of the titanium alloy spherical plain bearing. After laser etching, the workpiece is immediately immersed in anhydrous ethanol for ultrasonic cleaning to remove residual laser etching products on the surface.

[0083] Step 2.3: Polish the inner ring of the spherical plain bearing, and then perform a secondary ultrasonic cleaning using a mixed solution of alcohol and acetone with a volume ratio of 1 to 2:1; after completion, dry it to finally form a uniform and dense micro-arc oxidation-textured surface on the surface of the inner ring of the titanium alloy spherical plain bearing.

[0084] Step 3: Electrochemically deposit hydroxyapatite to form a porous liquid storage coating structure, and prepare a hydroxyapatite composite lubrication interface on the outer surface of the inner ring of the spherical plain bearing.

[0085] Step 3 is implemented as follows:

[0086] Step 3.1, select anhydrous CaCl2, NH4H2PO4, and NaCl as electrolytes to prepare an electrolyte, wherein the concentration of anhydrous CaCl2 is 0.23-0.26 mol / L, the concentration of NH4H2PO4 is 0.13-0.15 mol / L, and the concentration of NaCl is 0.095-0.105 mol / L, so that the n(Ca2+):n(PO4 3- ) is 1.6-1.75 and pH is 4.2-7.0;

[0087] Step 3.2: Electrochemically deposit a hydroxyapatite coating on the outer surface of the inner ring of the micro-arc oxidation-textured spherical plain bearing obtained in step 2.3. The processing process is as follows: Figure 3 Add the electrolyte prepared in step 3.1 into the container in a quantitative manner, with the volume of the electrolyte accounting for 70%-80% of the total capacity of the container. In the container, use the titanium alloy bearing as the cathode and the graphite plate as the anode, and maintain a distance of 1-5 cm between the two electrodes.

[0088] Step 3.3: Place the container containing the electrolyte in step 3.2 into a heat-collecting constant-temperature heater. Maintain a constant temperature during the electrochemical reaction using a constant-temperature oil bath. Place a rotor in the reaction container for magnetic stirring at a speed of 500-1000 rpm to ensure that the chemicals in the electrolyte are evenly dispersed during the reaction. Place the titanium alloy spherical bearing and the graphite plate in a pure copper semi-enclosed electrode holder and connect them to the negative and positive electrodes of a DC regulated power supply, respectively.

[0089] Step 3.4: Perform electrochemical deposition using a constant voltage method, set the DC regulated voltage to 2-4V, the deposition temperature to 40-80°C, start deposition and time the deposition after preparation, and the deposition time is 15-40 minutes;

[0090] Step 3.5, the inner surface of the titanium alloy spherical bearing after electrochemical deposition in step 3.4 is left to stand and dry naturally, and then placed in a box-type resistance furnace for heating at a temperature of 600-800°C and kept warm for 2-3 hours, and the inner surface of the inner ring of the titanium alloy spherical bearing is ultrasonically cleaned with alcohol, the ultrasonic cleaning frequency is 40-60kHz, the ultrasonic cleaning temperature is 30-50°C, and the ultrasonic cleaning time is 10-20min. After the cleaning is completed, the inner ring of the titanium alloy spherical bearing is taken out, immediately rinsed with deionized water to remove the residual cleaning liquid, and blown dry with a clean air flow, and finally a micro-arc oxidation-texture-hydroxyapatite composite surface is obtained on the inner ring of the titanium alloy spherical bearing. Figure 4 The microstructure and element distribution characteristics of the composite surface are demonstrated. Figure 4 (a) is a low-magnification SEM image of the composite surface, showing a uniform porous structure with interconnected pores, which is conducive to the adsorption and storage of lubricating oil. Figure 4 (b) is a high-magnification image. The surface is composed of densely arranged spiny hydroxyapatite crystals with high crystallinity, which helps to improve the structural stability and wear resistance of the coating. Figure 4 (c) is the EDS spectrum of the undeposited area, with a strong Ti element signal and weak Ca and P signals, indicating that the area is a titanium substrate or the coating coverage is incomplete; Figure 4 (d) shows that the Ca, P and O element signals are enhanced and evenly distributed, and the Ti signal is almost invisible, confirming that the deposited coating is dense, continuous and has a stable composition, providing a good structural and compositional basis for subsequent lubrication performance.

[0091] Example 3

[0092] The method for preparing the surface of a porous oil-containing hydroxyapatite spherical bearing based on electrochemical deposition of the present invention is specifically implemented according to the following steps:

[0093] Step 1, preparation of micro-arc coating of titanium alloy spherical plain bearing;

[0094] Step 1 is implemented as follows:

[0095] Step 1.1: Pre-treat the inner ring of the titanium alloy spherical plain bearing by ultrasonically cleaning it with anhydrous ethanol or acetone to remove oil, dust, and other contaminants on the surface. Rinse it with deionized water and dry it. Pickle it with a dilute nitric acid solution to remove the natural oxide layer on the surface. Rinse it with deionized water after pickling and neutralize it with an alkaline solution. Rinse it again and dry it to keep the workpiece surface clean and free of impurities.

[0096] Step 1.2: Using high-voltage electrostatic spraying equipment, a polytetrafluoroethylene protective coating with a mass concentration of 5-10wt% is evenly sprayed on the inner surface of the inner ring of the spherical plain bearing. The protective coating is evenly sprayed on the inner surface of the inner ring of the titanium alloy spherical plain bearing, thereby achieving a uniform and dense protective layer of 0.2 to 0.5 mm to isolate the erosion of chemical media during subsequent micro-arc oxidation and electrochemical deposition. After spraying, the inner ring of the titanium alloy spherical plain bearing is allowed to stand and dry at room temperature and solidify. In step 1.2, the spraying distance is set to 15 cm and the spraying pressure is set to 0.2 MPa. The coating is allowed to stand and dry for 20 minutes, and then transferred to a 120°C oven for curing for 60 minutes.

[0097] Step 1.3, prepare an electrolyte: weigh 0.18wt% calcium nitrate, 0.70wt% ammonium dihydrogen phosphate, 0.20wt% sodium hydroxide, and the remainder deionized water, such that the sum of the mass percentages of the above components is 100%, to adjust the solution pH to 4.2, then stir and mix thoroughly until a uniform electrolyte is formed, and let it stand for later use;

[0098] Step 1.4: Place the inner ring of the titanium alloy spherical bearing cleaned in step 1.2 into the electrolyte prepared in step 1.3, start the micro-arc oxidation equipment, select the constant current mode, and ensure that the oxidation process is stable; in step 1.4, set the frequency to 500 Hz, the pulse width to 120 μs, and the time to 0 min.

[0099] Step 1.5: After the treatment is completed, remove the inner ring of the titanium alloy spherical plain bearing from the electrolytic tank, rinse it with deionized water to remove the residual electrolyte on the surface, dry it naturally or use hot air to form a micro-arc oxidation surface on the outer surface of the inner ring of the titanium alloy spherical plain bearing.

[0100] Step 2: surface texture design and laser etching;

[0101] Step 2 is implemented as follows:

[0102] Step 2.1, inspired by the Nepenthes-divergent composite wetting track, a Nepenthes-like composite lubrication track is designed on the outer surface of the inner ring of the spherical bearing (such as Figure 1 、 Figure 2 As shown in the figure, the pitcher plant-like composite lubrication track is arranged axially as a whole. The main body consists of a central linear guide track and multiple divergent branch tracks on both sides. The overall shape is "fishbone-shaped" or "swallowtail-shaped" and has bidirectional wetting guidance and central liquid collection functions. The linear track plays a leading role in transmission, while the divergent track realizes the drainage, uniform distribution and edge locking control of the droplets.

[0103] The specific texture parameters of the pitcher plant-like composite lubrication track in step 2.1 are summarized as follows: the pitcher plant-linear track spacing b is set to 0.8 mm; the divergent track width W2 is 1.5 mm; the total width W of the composite wetting track is 3.5 mm; the total length L of the pitcher plant-like track is 7 mm; at the same time, the texture width d is 200 μm, the texture depth h is 10-50 μm; the texture angle α is 60°, and a divergence angle Dα of 5° is introduced to achieve efficient directional spreading and driving effect of droplets on the track.

[0104] Step 2.2: Laser etching is performed on the outer surface of the inner ring of the titanium alloy spherical plain bearing. After laser etching, the workpiece is immediately immersed in anhydrous ethanol for ultrasonic cleaning to remove residual laser etching products on the surface.

[0105] In step 2.2, the laser power is 25 W, the frequency is 40 kHz, the pulse width is 150 ns, the processing speed is 20 mm / s, the number of scans is 2 times, and the ultrasonic cleaning time is 10 min.

[0106] Step 2.3: Polish the inner ring of the spherical plain bearing, and then perform a secondary ultrasonic cleaning using a mixed solution of alcohol and acetone with a volume ratio of 1 to 2:1; after completion, dry it to finally form a uniform and dense micro-arc oxidation-textured surface on the surface of the inner ring of the titanium alloy spherical plain bearing.

[0107] In step 2.3, the rotation speed is set to 20 rpm, the processing time is 20 min, the cleaning time is 10 min, the drying temperature is 80°C, and the drying time is 15 min.

[0108] Step 3: Electrochemically deposit hydroxyapatite to form a porous liquid storage coating structure, and prepare a hydroxyapatite composite lubrication interface on the outer surface of the inner ring of the spherical plain bearing.

[0109] Step 3 is implemented as follows:

[0110] Step 3.1, select anhydrous CaCl2, NH4H2PO4, and NaCl as electrolytes to prepare an electrolyte, wherein the concentration of anhydrous CaCl2 is 0.26 mol / L, the concentration of NH4H2PO4 is 0.15 mol / L, and the concentration of NaCl is 0.105 mol / L, so that n(Ca 2+ ):n(PO4 3- ) is 1.75 and pH is 7.0;

[0111] Step 3.2: Electrochemically deposit a hydroxyapatite coating on the outer surface of the inner ring of the micro-arc oxidation-textured spherical plain bearing obtained in step 2.3. The processing process is as follows: Figure 3Add the electrolyte prepared in step 3.1 into the container in a certain amount, so that the volume of the electrolyte accounts for 80% of the total capacity of the container. In the container, use the titanium alloy bearing as the cathode and the graphite plate as the anode, and keep the distance between the two electrodes at 1-5 cm.

[0112] Step 3.3: Place the container containing the electrolyte in step 3.2 into a heat-collecting constant-temperature heater. Maintain a constant temperature during the electrochemical reaction using a constant-temperature oil bath. Place a rotor in the reaction container for magnetic stirring at a speed of 1000 rpm to ensure that the chemicals in the electrolyte are evenly dispersed during the reaction. Place the titanium alloy spherical bearing and the graphite plate in a pure copper semi-enclosed electrode holder and connect them to the negative and positive electrodes of a DC regulated power supply, respectively.

[0113] Step 3.4: Electrochemical deposition was performed using a constant voltage method. The DC voltage was set to 2-4 V and the deposition temperature was set to 80°C. After the deposition was complete, the deposition was started and the timing was set to 40 min.

[0114] Step 3.5. Let the inner surface of the titanium alloy spherical bearing after electrochemical deposition in step 3.4 stand and dry naturally, then place it in a box-type resistance furnace for heating at a temperature of 800°C and keep it warm for 3 hours. Use alcohol to ultrasonically clean the inner surface of the inner ring of the titanium alloy spherical bearing. The ultrasonic cleaning frequency is 60kHz, the ultrasonic cleaning temperature is 50°C, and the ultrasonic cleaning time is 20 minutes. After cleaning, take out the inner ring of the titanium alloy spherical bearing, immediately rinse it with deionized water to remove the residual cleaning liquid, and blow it dry with a clean air flow. Finally, a micro-arc oxidation-texture-hydroxyapatite composite surface is obtained on the inner ring of the titanium alloy spherical bearing.

[0115] Example 4

[0116] 1. Pre-treat the inner ring of the titanium alloy spherical plain bearing by ultrasonically cleaning it with anhydrous ethanol to remove oil, dust, and other contaminants from the surface. Rinse it with deionized water and dry it. Pickle it with a dilute nitric acid solution to remove the natural oxide layer on the surface. Immediately rinse it with deionized water and neutralize it with an alkaline solution. Rinse it again and dry it to keep the surface clean and free of impurities.

[0117] 2. Use high-voltage electrostatic spraying equipment to evenly spray the appropriately diluted high-temperature resistant and corrosion-resistant polytetrafluoroethylene protective coating on the inner surface of the inner ring of the spherical bearing. The equipment is set to a spray distance of 25 cm and the spray pressure is controlled at 0.2 MPa, thereby achieving a 0.4 mm uniform and dense protective layer to isolate the erosion of chemical media during subsequent micro-arc oxidation and electrochemical deposition. After spraying, the workpiece is dried at room temperature for 15 minutes and then transferred to a 90°C oven for curing for 50 minutes.

[0118] 3. Add 45L of deionized water to the electrolytic cell, followed by 110g of calcium nitrate and 420g of ammonium dihydrogen phosphate. Add 160g of sodium hydroxide to adjust the pH of the solution to 5.0. Stir thoroughly until a uniform electrolyte solution is formed, then set aside.

[0119] 4. Place the cleaned spherical plain bearing inner ring in the electrolyte and start the micro-arc oxidation equipment. Select the constant current mode on the operation panel, set the frequency to 550Hz, the pulse width to 140μs, and the duration to 15 minutes to ensure a stable oxidation process. This will cause a plasma discharge reaction on the surface, forming a uniform and dense oxide layer.

[0120] 5. After treatment, remove the workpiece from the electrolytic bath and rinse with deionized water to remove any residual electrolyte. Allow to air dry or use hot air to ensure surface integrity. The outer surface of the spherical plain bearing inner ring after micro-arc oxidation forms a micro-arc oxidized surface.

[0121] 6. Set the texture parameters: Set the pitcher plant-linear track spacing b to 0.4 mm; the divergent track width W2 to 1.3 mm; the total composite wetting track width W to 2.2 mm; and the total pitcher plant track length L to 7 mm. Also, set the texture width (d) to 120 μm, the texture depth (h) to 25 μm, the texture angle (α) to 50°, and introduce a 3° divergence angle (Dα) to achieve efficient directional spreading and driving of droplets on the track.

[0122] 7. Laser etching was used to process the outer surface of the inner ring of the spherical plain bearing. The laser power was 22.5W, the frequency was 32kHz, the pulse width was 100ns, the processing speed was 25mm / s, and the number of scans was 1. After laser etching, the workpiece was immediately immersed in anhydrous ethanol for ultrasonic cleaning for about 10 minutes to remove the residual laser etching products on the surface.

[0123] 8. The workpiece was transferred to an automated magnetic field-assisted polishing device for surface treatment. The equipment speed was set to approximately 38 rpm and the treatment time was controlled within 25 minutes. The workpiece was then ultrasonically cleaned for a second time with an alcohol-acetone mixed solution for 20 minutes and dried in an oven at 100°C. Finally, a uniform and dense micro-arc oxidation-textured surface was formed on the workpiece surface.

[0124] 9. The electrolyte is anhydrous calcium chloride-ammonium dihydrogen phosphate-sodium chloride. Use an analytical balance to accurately weigh the electrolyte raw materials. 2+ ):n(PO4 3- ) was maintained at 1.65 and the pH value was maintained at 4.8. Then a certain amount of electrolyte was placed in a beaker and sealed with aluminum foil.

[0125] 10. Electrochemically deposit a hydroxyapatite coating on the outer surface of the machined micro-arc oxidation-textured spherical plain bearing inner ring. The titanium alloy bearing was used as the cathode and the graphite plate was used as the anode, with the two electrodes maintained at a distance of 3 cm.

[0126] 11. Place the beaker containing the electrolyte in a heat-collecting constant-temperature heater. Maintain a constant temperature during the electrochemical reaction using a constant-temperature oil bath. Place a rotor in the reaction beaker for magnetic stirring at 500 rpm to ensure uniform dispersion of the chemicals in the electrolyte during the reaction. Place the treated titanium alloy spherical plain bearing and graphite plate in a pure copper semi-enclosed electrode holder and connect them to the negative and positive electrodes of a DC regulated power supply, respectively.

[0127] 12. Use constant voltage method for electrochemical deposition. Set the deposition voltage to 2.8V on the DC regulated power supply and the deposition temperature to 60°C on the constant temperature heating magnetic stirrer. Start deposition and timing after preparation. The deposition time is 30 minutes.

[0128] 13. Coating heat treatment: The electrochemically deposited hydroxyapatite coating was allowed to dry naturally, then heated to 700°C in a box-type resistance furnace for 2 hours. The inner surface of the spherical plain bearing inner ring was ultrasonically cleaned using alcohol at a frequency of 40 kHz, a temperature of 35°C, and a duration of 10 minutes. After cleaning, the bearing was removed and immediately rinsed with deionized water to remove any residual cleaning solution. The bearing was then air-dried using a clean air stream to achieve a micro-arc oxidation-textured-hydroxyapatite composite surface. An oil-spinning test using PAO2 lubricant revealed an oil content of 21.75% on the micro-arc oxidation-textured-hydroxyapatite composite surface of the spherical plain bearing produced in this example.

[0129] Example 5

[0130] 1. Pre-treat the inner ring of the titanium alloy spherical plain bearing by ultrasonically cleaning it with anhydrous ethanol to remove oil, dust, and other contaminants from the surface. Rinse it with deionized water and dry it. Pickle it with a dilute nitric acid solution to remove the natural oxide layer on the surface. Immediately rinse it with deionized water and neutralize it with an alkaline solution. Rinse it again and dry it to keep the surface clean and free of impurities.

[0131] 2. Use high-voltage electrostatic spraying equipment to evenly spray the appropriately diluted high-temperature resistant and corrosion-resistant polytetrafluoroethylene protective coating on the inner surface of the inner ring of the spherical bearing. The equipment is set to a spray distance of 20 cm and the spray pressure is controlled at 0.3 MPa, thereby achieving a 0.3 mm uniform and dense protective layer to isolate the erosion of chemical media during subsequent micro-arc oxidation and electrochemical deposition. After spraying, the workpiece is dried at room temperature for 10 minutes and then transferred to a 100°C oven for curing for 40 minutes.

[0132] 3. Add 50L of deionized water to the electrolytic cell, add 100g of calcium nitrate and 400g of ammonium dihydrogen phosphate, and adjust the pH of the solution to 4.2 by adding 150g of sodium hydroxide. After adding all the components, stir thoroughly until a uniform electrolyte is formed, and let it stand for later use.

[0133] 4. Place the cleaned spherical plain bearing inner ring in the electrolyte and start the micro-arc oxidation equipment. Select the constant current mode on the operation panel, set the frequency to 600Hz, the pulse width to 150μs, and the duration to 20 minutes to ensure a stable oxidation process. This will cause a plasma discharge reaction on the surface, forming a uniform and dense oxide layer.

[0134] 5. After treatment, remove the workpiece from the electrolytic bath and rinse with deionized water to remove any residual electrolyte. Allow to air dry or use hot air to ensure surface integrity. The outer surface of the spherical plain bearing inner ring after micro-arc oxidation forms a micro-arc oxidized surface.

[0135] 6. Set the texture parameters: Set the pitcher plant-linear track spacing b to 0.5 mm; the divergent track width W2 to 1.2 mm; the total composite wetting track width W to 2 mm; and the total pitcher plant track length L to 6 mm. Also, set the texture width (d) to 100 μm, the texture depth (h) to 20 μm, the texture angle (α) to 45°, and introduce a 4° divergence angle (Dα) to achieve efficient directional spreading and driving of droplets on the track.

[0136] 7. Laser etching was used to process the outer surface of the inner ring of the spherical plain bearing. The laser power was 22.5W, the frequency was 30KHz, the pulse width was 100ns, the processing speed was 30mm / s, and the number of scans was 1. After laser etching, the workpiece was immediately immersed in anhydrous ethanol for ultrasonic cleaning for about 10 minutes to remove the residual laser etching products on the surface.

[0137] 8. The workpiece was transferred to an automated magnetic field-assisted polishing device for surface treatment. The equipment speed was set to approximately 30 rpm and the treatment time was controlled within 20 minutes. The workpiece was then ultrasonically cleaned for a second time with an alcohol-acetone mixed solution for 20 minutes and dried in an oven at 90°C. Finally, a uniform and dense micro-arc oxidation-textured surface was formed on the workpiece surface.

[0138] 9. The electrolyte is anhydrous calcium chloride-ammonium dihydrogen phosphate-sodium chloride. Use an analytical balance to accurately weigh the electrolyte raw materials. 2+ ):n(PO4 3- ) was maintained at 1.67 and the pH was maintained at 4.2. A certain amount of electrolyte was then placed in a beaker and sealed with aluminum foil.

[0139] 10. Electrochemically deposit a hydroxyapatite coating on the outer surface of the machined micro-arc oxidation-textured spherical plain bearing inner ring. The titanium alloy bearing was used as the cathode and the graphite plate was used as the anode, with the two electrodes spaced 2 cm apart.

[0140] 11. Place the beaker containing the electrolyte in a heat-collecting constant-temperature heater. Maintain a constant temperature during the electrochemical reaction using a constant-temperature oil bath. Place a rotor in the reaction beaker for magnetic stirring at 800 rpm to ensure uniform dispersion of the chemicals in the electrolyte during the reaction. Place the treated titanium alloy spherical plain bearing and graphite plate in a pure copper semi-enclosed electrode holder and connect them to the negative and positive electrodes of a DC regulated power supply, respectively.

[0141] 12. Use constant voltage method for electrochemical deposition. Set the deposition voltage to 2.8V on the DC regulated power supply and the deposition temperature to 50°C on the constant temperature heating magnetic stirrer. Start deposition and timing after preparation. The deposition time is 25 minutes.

[0142] 13. Heat treatment of the coating: the hydroxyapatite coating after electrochemical deposition is allowed to stand and dry naturally, then placed in a box-type resistance furnace and heated to 800°C and kept warm for 2 hours. Use alcohol to ultrasonically clean the inner surface of the inner ring of the spherical bearing with a frequency set to 60kHz, a temperature controlled at 40°C, and a time set to 15 minutes. After the cleaning is completed, the bearing is taken out and immediately rinsed with deionized water to remove the residual cleaning liquid, and blown dry with a clean air flow. Finally, the spherical bearing obtains a micro-arc oxidation-texture-hydroxyapatite composite surface. Use a high-speed photography platform to record the impact process of the PAO2 lubricant on the micro-arc oxidation-texture-hydroxyapatite composite surface prepared in this embodiment in a horizontal form (such as Figure 5 ), keeping the droplet size the same (all 150 μL), controlling the droplet landing height to 2.5 cm, and ensuring that the droplet velocity at 0 ms is approximately 0.5 m / s. The pore structure of the micro-arc oxidation-texture-hydroxyapatite composite surface can quickly adsorb droplets through capillary action, allowing the droplets to penetrate into the interior, thereby improving the liquid storage capacity and reducing lubricant loss. In addition, after the droplet impacts the composite surface, the morphology undergoes three stages: impact, spreading penetration, and retraction. Compared with ordinary surfaces, the micro-arc oxidation-texture-hydroxyapatite composite surface can enhance the spreading ability of droplets and, to a certain extent, adjust the spreading radius and penetration depth.

[0143] Example 6

[0144] 1. Pre-treat the inner ring of the titanium alloy spherical plain bearing by ultrasonically cleaning it with anhydrous ethanol to remove oil, dust, and other contaminants from the surface. Rinse it with deionized water and dry it. Pickle it with a dilute nitric acid solution to remove the natural oxide layer on the surface. Immediately rinse it with deionized water and neutralize it with an alkaline solution. Rinse it again and dry it to keep the surface clean and free of impurities.

[0145] 2. Use high-voltage electrostatic spraying equipment to evenly spray the appropriately diluted high-temperature resistant and corrosion-resistant polytetrafluoroethylene protective coating on the inner surface of the inner ring of the spherical bearing. The equipment is set to a spray distance of 25 cm and the spray pressure is controlled at 0.25 MPa, thereby achieving a 0.4 mm uniform and dense protective layer to isolate the erosion of chemical media during subsequent micro-arc oxidation and electrochemical deposition. After spraying, the workpiece is dried at room temperature for 15 minutes and then transferred to a 120°C oven for curing for 50 minutes.

[0146] 3. Add 55L of deionized water to the electrolytic cell, followed by 120g of calcium nitrate and 420g of ammonium dihydrogen phosphate. Add 160g of sodium hydroxide to adjust the pH of the solution to 5.2. Stir thoroughly until a uniform electrolyte solution is formed, then set aside.

[0147] 4. Place the cleaned spherical plain bearing inner ring in the electrolyte and start the micro-arc oxidation equipment. Select the constant current mode on the operation panel, set the frequency to 580Hz, the pulse width to 180μs, and the duration to 25 minutes to ensure a stable oxidation process. This will cause a plasma discharge reaction on the surface, forming a uniform and dense oxide layer.

[0148] 5. After treatment, remove the workpiece from the electrolytic bath and rinse with deionized water to remove any residual electrolyte. Allow to air dry or use hot air to ensure surface integrity. The outer surface of the spherical plain bearing inner ring after micro-arc oxidation forms a micro-arc oxidized surface.

[0149] 6. Set the texture parameters: Set the pitcher plant-linear track spacing b to 0.4 mm; the divergent track width W2 to 1.5 mm; the total composite wetting track width W to 3 mm; and the total pitcher plant track length L to 7 mm. Also, set the texture width (d) to 120 μm, the texture depth (h) to 25 μm, the texture angle (α) to 40°, and introduce a 3° divergence angle (Dα) to achieve efficient directional spreading and driving of droplets on the track.

[0150] 7. Laser etching was used to process the outer surface of the inner ring of the spherical plain bearing. The laser power was 23W, the frequency was 32kHz, the pulse width was 120ns, the processing speed was 25mm / s, and the number of scans was 1. After laser etching, the workpiece was immediately immersed in anhydrous ethanol for ultrasonic cleaning for about 20 minutes to remove the residual laser etching products on the surface.

[0151] 8. The workpiece was transferred to an automated magnetic field-assisted polishing device for surface treatment. The equipment speed was set to approximately 40 rpm and the treatment time was controlled within 20 min. The workpiece was then ultrasonically cleaned for a second time with an alcohol-acetone mixed solution for 20 min and dried in an oven at 80°C to form a uniform and dense micro-arc oxidation-textured surface on the workpiece surface.

[0152] 9. The electrolyte is anhydrous calcium chloride-ammonium dihydrogen phosphate-sodium chloride. Use an analytical balance to accurately weigh the electrolyte raw materials. 2+ ):n(PO4 3- ) was maintained at 1.72 and the pH was maintained at 6.0. A certain amount of electrolyte was then placed in a beaker and sealed with aluminum foil.

[0153] 10. Electrochemically deposit a hydroxyapatite coating on the outer surface of the machined micro-arc oxidation-textured spherical plain bearing inner ring. The titanium alloy bearing was used as the cathode and the graphite plate was used as the anode, with the two electrodes maintained at a distance of 3 cm.

[0154] 11. Place the beaker containing the electrolyte in a heat-collecting constant-temperature heater. Maintain a constant temperature during the electrochemical reaction using a constant-temperature oil bath. Place a rotor in the reaction beaker for magnetic stirring at 1000 rpm to ensure uniform dispersion of the chemicals in the electrolyte during the reaction. Place the treated titanium alloy spherical plain bearing and graphite plate in a pure copper semi-enclosed electrode holder and connect them to the negative and positive electrodes of a DC regulated power supply, respectively.

[0155] 12. Use constant voltage method for electrochemical deposition. Set the deposition voltage to 2.6V on the DC regulated power supply and the deposition temperature to 50°C on the constant temperature heating magnetic stirrer. Start deposition and timing after preparation. The deposition time is 25 minutes.

[0156] 13. Heat treatment of the coating: the hydroxyapatite coating after electrochemical deposition is allowed to stand and dry naturally, then placed in a box-type resistance furnace and heated to 600°C and kept warm for 3 hours. Use alcohol to perform ultrasonic cleaning on the inner surface of the inner ring of the spherical bearing. The frequency is set to 50kHz, the temperature is controlled at 40°C, and the time is set to 15 minutes. After the cleaning is completed, the bearing is taken out and immediately rinsed with deionized water to remove the residual cleaning liquid. It is blown dry with a clean air flow, and finally the spherical bearing obtains a micro-arc oxidation-texture-hydroxyapatite composite surface. A high-speed camera is used to record the spreading experiment of PAO2 lubricating oil droplets on the micro-arc oxidation-texture-hydroxyapatite composite surface prepared in this embodiment. The spreading flow process of the droplets is photographed in the form of a bird's-eye view at an interval of 1.8 seconds (such as Figure 6 ).

Claims

1. A method for preparing a porous oil-containing hydroxyapatite joint bearing surface based on electrochemical deposition, characterized in that: Please follow the steps below to implement it: Step 1, preparation of micro-arc coating of titanium alloy spherical plain bearing; Step 2: surface texture design and laser etching; Step 3: Electrochemically deposit hydroxyapatite to form a porous liquid storage coating structure, and prepare a hydroxyapatite composite lubrication interface on the outer surface of the inner ring of the spherical plain bearing.

2. The method for preparing a porous oil-containing hydroxyapatite joint bearing surface based on electrochemical deposition according to claim 1, characterized in that: The step 1 is specifically implemented according to the following steps: Step 1.1: Pre-treat the inner ring of the titanium alloy spherical plain bearing by ultrasonically cleaning it with anhydrous ethanol or acetone to remove oil, dust, and other contaminants on the surface. Rinse it with deionized water and dry it. Pickle it with a dilute nitric acid solution to remove the natural oxide layer on the surface. Rinse it with deionized water after pickling and neutralize it with an alkaline solution. Rinse it again and dry it to keep the workpiece surface clean and free of impurities. Step 1.2: Using high-voltage electrostatic spraying equipment, a polytetrafluoroethylene protective coating having a mass concentration of 5-10 wt% is evenly sprayed onto the inner surface of the inner ring of the spherical plain bearing. The protective coating is evenly sprayed onto the inner surface of the inner ring of the titanium alloy spherical plain bearing, thereby achieving a uniform and dense protective layer of 0.2 to 0.5 mm to isolate the erosion of chemical media during subsequent micro-arc oxidation and electrochemical deposition processes. After spraying, the inner ring of the titanium alloy spherical plain bearing is allowed to stand at room temperature to dry and solidify. Step 1.3, preparing an electrolyte: weighing 0.12-0.18wt% calcium nitrate, 0.50-0.70wt% ammonium dihydrogen phosphate, 0.20-0.30wt% sodium hydroxide, and the remainder deionized water, such that the sum of the mass percentages of the above components is 100%, to adjust the solution pH to 4.2-7.0, then stir and mix thoroughly until a uniform electrolyte is formed, and let it stand for use; Step 1.4: Place the inner ring of the titanium alloy spherical plain bearing cleaned in step 1.2 into the electrolyte prepared in step 1.3, start the micro-arc oxidation equipment, select the constant current mode, and ensure that the oxidation process is stable; Step 1.5: After the treatment is completed, remove the inner ring of the titanium alloy spherical plain bearing from the electrolytic tank, rinse it with deionized water to remove the residual electrolyte on the surface, dry it naturally or use hot air to form a micro-arc oxidation surface on the outer surface of the inner ring of the titanium alloy spherical plain bearing.

3. The method for preparing a porous oil-containing hydroxyapatite joint bearing surface based on electrochemical deposition according to claim 2, characterized in that: In step 1.2, the spraying distance is set to 15-30 cm, the spraying pressure is set to 0.2-0.4 MPa, and the coating is allowed to dry for 10-20 minutes, and then transferred to an oven at 80-120°C for curing for 30-60 minutes; In step 1.4, the frequency is set to 500-700 Hz, the pulse width is set to 120-180 μs, and the time is set to 10-30 minutes.

4. The method for preparing a porous oil-containing hydroxyapatite joint bearing surface based on electrochemical deposition according to claim 2, characterized in that: The step 2 is specifically implemented according to the following steps: Step 2.

1. Design a pitcher plant-like composite lubrication track on the outer surface of the inner ring of the spherical plain bearing. The pitcher plant-like composite lubrication track is arranged axially. The main body consists of a central linear guide track and multiple divergent branch tracks on both sides. The overall shape is "fishbone" or "swallowtail" expansion, and it has bidirectional wetting guidance and central liquid collection functions. The linear track plays a leading role in transmission, while the divergent tracks achieve droplet drainage, uniform distribution, and edge locking control. Step 2.2: Laser etching is performed on the outer surface of the inner ring of the titanium alloy spherical plain bearing. After laser etching, the workpiece is immediately immersed in anhydrous ethanol for ultrasonic cleaning to remove residual laser etching products on the surface. Step 2.3: Polish the inner ring of the spherical plain bearing, and then perform a secondary ultrasonic cleaning using a mixed solution of alcohol and acetone with a volume ratio of 1 to 2:1; after completion, dry it to finally form a uniform and dense micro-arc oxidation-textured surface on the surface of the inner ring of the titanium alloy spherical plain bearing.

5. The method for preparing a porous oil-containing hydroxyapatite joint bearing surface based on electrochemical deposition according to claim 4, characterized in that: The specific texture parameters of the pitcher plant-like composite lubrication track in step 2.1 are summarized as follows: the pitcher plant-linear track spacing b is set to 0.3-0.8 mm; the divergent track width W2 is set to 1.0-1.5 mm; the total width W of the composite wetting track is set to 1.5-3.5 mm; the total length L of the pitcher plant-like track is set to 5-7 mm; at the same time, the texture width d is 50-200 μm, the texture depth h is 10-50 μm; the texture angle α is 30°-60°, and a divergence angle Dα of 2°-5° is introduced.

6. The method for preparing a porous oil-containing hydroxyapatite spherical bearing surface based on electrochemical deposition according to claim 5, characterized in that: In the step 2.2, the laser power is 20-25 W, the frequency is 20-40 KHz, the pulse width is 50-150 ns, the processing speed is 20-40 mm / s, the number of scans is 1-2 times, and the ultrasonic cleaning time is 10-20 min.

7. The method for preparing a porous oil-containing hydroxyapatite joint bearing surface based on electrochemical deposition according to claim 5, characterized in that: In step 2.3, the rotation speed is set to 20-40 rpm, the processing time is set to 20-30 minutes, the cleaning time is set to 10-20 minutes, the drying temperature is set to 80-100° C., and the drying time is set to 15-30 minutes.

8. The method for preparing a porous oil-containing hydroxyapatite spherical bearing surface based on electrochemical deposition according to claim 4, characterized in that: The step 3 is specifically implemented according to the following steps: Step 3.1, select anhydrous CaCl2, NH4H2PO4, and NaCl as electrolytes to prepare an electrolyte, wherein the concentration of anhydrous CaCl2 is 0.23-0.26 mol / L, the concentration of NH4H2PO4 is 0.13-0.15 mol / L, and the concentration of NaCl is 0.095-0.105 mol / L, so that n(Ca 2+ ):n(PO4 3- ) is 1.6-1.75 and pH is 4.2-7.0; Step 3.2: Electrochemically deposit a hydroxyapatite coating on the outer surface of the inner ring of the micro-arc oxidation-textured spherical plain bearing obtained in step 2.

3. The electrolyte prepared in step 3.1 is added to a container in a predetermined amount, with the volume of the electrolyte accounting for 70%-80% of the total volume of the container. In the container, the titanium alloy bearing serves as the cathode and the graphite plate serves as the anode, with the distance between the two electrodes maintained at 1-5 cm. Step 3.3: Place the container containing the electrolyte in step 3.2 into a heat-collecting constant-temperature heater. Maintain a constant temperature during the electrochemical reaction using a constant-temperature oil bath. Place a rotor in the reaction container for magnetic stirring at a speed of 500-1000 rpm to ensure that the chemicals in the electrolyte are evenly dispersed during the reaction. Place the titanium alloy spherical bearing and the graphite plate in a pure copper semi-enclosed electrode holder and connect them to the negative and positive electrodes of a DC regulated power supply, respectively. Step 3.4: Perform electrochemical deposition using a constant voltage method, set the DC regulated voltage to 2-4V, the deposition temperature to 40-80°C, start deposition and time the deposition after preparation, and the deposition time is 15-40 minutes; Step 3.5, let the inner surface of the titanium alloy spherical bearing after electrochemical deposition in step 3.4 stand and dry naturally, then heat it to a temperature of 600-800°C and keep it warm for 2-3 hours, use alcohol to ultrasonically clean the inner surface of the inner ring of the titanium alloy spherical bearing, the ultrasonic cleaning frequency is 40-60kHz, the ultrasonic cleaning temperature is 30-50°C, and the ultrasonic cleaning time is 10-20min. After cleaning, take out the inner ring of the titanium alloy spherical bearing, immediately rinse it with deionized water to remove the residual cleaning liquid, and blow it dry with a clean air flow to finally obtain a micro-arc oxidation-texture-hydroxyapatite composite surface on the inner ring of the titanium alloy spherical bearing.

Images