Preparation Method of High-Strength Wear-Resistant Composite Coating on Surface of Spherical Plain Bearing

Abstract

A preparation method for a high-strength wear-resistant composite coating on the surface of a spherical plain bearing, which relates to a preparation method for a high-strength wear-resistant composite coating. The present invention aims to solve the technical problem that the current valve metal spherical plain bearings have high costs and their overall performance is poor due to their overly rough surfaces. The present invention uses a magnetron sputtering combined with a micro-arc oxidation process to prepare a high-strength wear-resistant composite coating on the surface of a spherical plain bearing. First, a Ti film is deposited on the outer spherical surface of the inner ring of a non-valve metal spherical plain bearing by magnetron sputtering technology. Then, a super-hydrophilic titanium dioxide ceramic film with excellent bonding force to the substrate and a rough and porous surface is obtained by micro-arc oxidation. Then, this layer is used as a primer layer. Finally, a CoCrFeNiTi high-entropy coating is deposited on the surface of the titanium dioxide ceramic coating by magnetron sputtering to fill the pores of the original micro-arc oxidation ceramic primer layer, significantly reducing the roughness of the bearing working surface and improving the wear resistance of the parts.

Description

Technical Field

[0001] The invention relates to a method for preparing a high-strength wear-resistant composite coating. Background Art

[0002] Spherical bearings are key load-bearing components of mechanical devices. They are located in the core parts of various mechanical devices and are widely used in equipment, automotive products, and special working condition robots. Among them, the working conditions required for carrier-based aircraft load-bearing spherical bearings are the most demanding. Spherical bearings are the core components that determine the operation of the main engine of carrier-based aircraft. They are responsible for ensuring that they can run quickly and smoothly during various flight actions of carrier-based aircraft. These bearings are often subjected to extremely high pressure, temperature, and friction during service. At the same time, they must maintain high precision and long life to ensure the safety and reliability of the flight, take-off and landing of carrier-based aircraft. Therefore, the surface wear resistance of carrier-based aircraft spherical bearings is very important. Surface modification of bearings through the design of new surface materials can greatly improve the wear resistance of bearings, thereby increasing the service life and service performance of bearings.

[0003] As a type of physical vapor deposition, magnetron sputtering technology is characterized by high deposition rate, low deposition temperature, uniform and smooth film layer, but poor bonding with the substrate. Micro-arc oxidation technology, on the other hand, is based on anodic oxidation and applies high voltage to break down the dielectric layer of the passivation film to produce arc discharge phenomenon. The high temperature and high pressure generated by arc discharge and the in-situ breakdown reaction of the material are used to obtain a ceramic film layer. It mainly oxidizes valve metals (metals with a wide passivation voltage range and capable of generating thicker and denser oxide films). When the valve metal is used as the anode, the surface will undergo anodic oxidation to generate a passivation film, thereby significantly enhancing the hardness of the material and forming a hydrophilic surface microstructure. When the valve metal is used as the anode, the ceramic film layer prepared has excellent bonding with the substrate and good wear resistance and corrosion resistance. However, although the surface with many pores and roughness is easy to form a super-hydrophilic surface, the overly rough surface has a great harm to its comprehensive performance. In addition, the cost of valve metal is relatively high, and valve metal without a fixed grade is difficult to arc during micro-arc oxidation and is not easy to form an oxide film.

[0004] Non-valve metal 42CrMo is the mainstream application product brand on the market. Its machining technology is more mature and suitable for mass production. In addition, the modulation treatment (quenching and tempering, etc.) process of 42CrMo bearing steel is more mature. Compared with other valve metal bearings, it can better meet the special use requirements under various working conditions. Summary of the invention

[0005] The present invention aims to solve the technical problems that the current valve metal spherical bearings have high costs and their overly rough surfaces lead to poor overall performance, and to provide a method for preparing a high-strength and wear-resistant composite coating on the surface of the spherical bearings.

[0006] The preparation method of the high-strength wear-resistant composite coating on the surface of the spherical plain bearing of the present invention is carried out according to the following steps:

[0007] 1. Fix the pretreated spherical plain bearing parts in the vacuum chamber of the magnetron sputtering equipment, use a Ti target as the cathode for magnetron sputtering, and prepare a Ti coating on the outer surface of the working surface of the inner ring of the spherical plain bearing;

[0008] The material of the spherical plain bearing is a non-valve metal;

[0009] 2. After the spherical plain bearing parts with a Ti coating on the surface obtained in step 1 are subjected to sealing and insulation treatment, place them in the micro-arc oxidation electrolyte as the anode for micro-arc oxidation to obtain a titanium dioxide ceramic film on the Ti film;

[0010] 3. After cleaning the surface of the specimen obtained in step 2, put it into the magnetron sputtering vacuum chamber again, and magnetron sputter to prepare a CoCrFeNiTi high-entropy coating on the micro-arc oxidation layer to form a three-layer composite coating.

[0011] Principle of the invention design:

[0012] The present invention adopts the magnetron sputtering combined with the micro-arc oxidation process to prepare a high-strength wear-resistant composite coating on the surface of the spherical plain bearing. First, a Ti film (valve metal) is deposited on the outer spherical surface of the inner ring of the non-valve metal spherical plain bearing by magnetron sputtering technology. Then, by using the high temperature and high pressure generated instantaneously by the arc discharge during micro-arc oxidation and the in-situ breakdown reaction of the material, a super-hydrophilic titanium dioxide ceramic film with excellent bonding force to the substrate and a rough and porous surface is obtained. Then, this layer is used as the bottom layer to improve the bonding force between the coating and the bearing substrate by utilizing the porous characteristics of the ceramic film, and by taking advantage of the porous structure, enhance the wettability of the subsequent thin film and improve the bonding strength. Then, a CoCrFeNiTi high-entropy coating is deposited on the surface of the titanium dioxide ceramic coating by magnetron sputtering to fill the pores of the original micro-arc oxidation ceramic bottom layer, significantly reducing the roughness of the bearing working surface and improving the wear resistance of the parts. At the same time, due to the "cocktail" mixing effect of the high-entropy alloy, the coating structure has the advantages of multiple components of high-entropy materials. And because the high-entropy thin film contains Ti elements, the compatibility between the high-entropy layer and the micro-arc oxidation layer is improved, and the bonding quality is enhanced. Finally, a Ti / TiO2 ceramic / CoCrFeNiTi composite coating with strong comprehensive surface performance is obtained.

[0013] The main functions of the three solutes in the micro-arc oxidation electrolyte solution in step 2 of the present invention are: Na3PO4·12H2O serves as the main film-forming agent during micro-arc oxidation to provide phosphate ions (PO4 3-), it can increase the solution conductivity to a certain extent, form a relatively thin initial passivation film, soften the subsequent breakdown arc, reduce the micro-discharge area, and obtain a continuous and flat oxide film; however, excessive phosphate ions will cause the discharge energy to concentrate in local micro-regions, resulting in macroscopic weak arc damage at multiple locations on the film layer. Therefore, the selected content of Na3PO4·12H2O is: Na3PO4·12H2O 8.67 g / L. Na2SiO3·9H2O provides silicate ions (SiO3 2- ), which greatly increases the solution conductivity, reduces the breakdown voltage, and facilitates the formation of a passivation film; at the same time, silicate (SiO3 2- ), in synergy with other anions in the electrolyte, can exacerbate the contrast between the strong and weak regions of the microscopic potential on the anode surface, promote the stable alternation state of the discharge sparks, and avoid macroscopic burning caused by local overheating. Considering the comprehensive effect, the selected content of NaSiO3·9H2O is: 9.34 g / L. NaF acts as a complexing agent in the solution. A small amount of NaF can improve the stability of the solution, delay the precipitation of precipitates, ensure the long-term effect of the electrolyte, and maintain the continuous and stable discharge process. Therefore, the content of NaF is: 1 g / L.

[0014] The present invention has the following beneficial effects:

[0015] 1. In the Ti / TiO2 ceramic / CoCrFeNiTi composite coating structure prepared by the present invention, the Ti / TiO2 ceramic layer located at the bottom layer forms a porous hard interface on the bearing surface. This interface exhibits superhydrophilic characteristics, greatly enhancing the bonding strength between the subsequent high-entropy coating and the bearing parts. At the same time, it also provides a high-strength and hard protective phase for the substrate, achieving a significant improvement in wear resistance;

[0016] 2. In the Ti / TiO2 ceramic / CoCrFeNiTi composite coating structure prepared by the present invention, the CoCrFeNiTi composite coating belongs to a composite high-entropy alloy material composed of a Cantor alloy equipped with multiple strengthening elements. In addition to good wear resistance, it has excellent antioxidant, high-temperature resistance, and corrosion resistance properties, making it one of the most prominent applications in the surface modification materials for bearing parts;

[0017] 3. Compared with traditional coating preparation methods, the micro-arc oxidation electrolyte does not contain heavy metals, has strong anti-pollution ability, and the electrolyte can be recycled, meeting the clean production standards; the magnetron sputtering process is environmentally friendly and pollution-free, and does not produce harmful waste;

[0018] 4. The present invention adopts magnetron sputtering technology and micro-arc oxidation technology. The equipment is simple and easy to operate, suitable for continuous operation and large-scale production, and can be applied industrially. Moreover, both technologies have the characteristics of conformal processing, and have good coating preparation and deposition efficiency for spherical plain bearings and other parts with special-shaped structures;

[0019] 5. The material of the spherical plain bearing used in the present invention is a non-valve metal, and the cost is significantly lower than that of valve metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a physical photo of the spherical plain bearing in Step 1 of Test 1;

[0021] Figure 2 It is a schematic diagram of the sealant insulation treatment in Step 2 of Test 1;

[0022] Figure 3 It is a comparison chart of the friction coefficient curves of the CoCrFeNiTi composite coating with a micro-arc oxidation primer layer prepared in Test 1 and the CoCrFeNiTi composite coating without a micro-arc oxidation primer layer prepared in the comparative test;

[0023] Figure 4 It is a SEM comparison image of the CoCrFeNiTi composite coating with a micro-arc oxidation primer layer prepared in Test 1 and the CoCrFeNiTi composite coating without a micro-arc oxidation primer layer prepared in the comparative test after the above-mentioned friction and wear experiments; DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE INVENTION 1: This embodiment is a method for preparing a high-strength wear-resistant composite coating on the surface of a spherical plain bearing, and the specific steps are as follows:

[0025] 1. Fix the pre-treated spherical plain bearing parts in the vacuum chamber of the magnetron sputtering equipment, use a Ti target as the cathode for magnetron sputtering, and prepare a Ti coating on the outer surface of the working surface of the inner ring of the spherical plain bearing;

[0026] The material of the spherical plain bearing is a non-valve metal;

[0027] 2. After the spherical plain bearing parts with a Ti coating on the surface obtained in Step 1 are subjected to sealant insulation treatment, place them in the micro-arc oxidation electrolyte as the anode for micro-arc oxidation to obtain a titanium dioxide ceramic film on the Ti film;

[0028] 3. After cleaning the surface of the specimen obtained in Step 2, put it into the magnetron sputtering vacuum chamber again, and magnetron sputter to prepare a CoCrFeNiTi high-entropy coating on the micro-arc oxidation layer to form a three-layer composite coating.

[0029] DETAILED DESCRIPTION OF THE INVENTION 2: The difference between this embodiment and DETAILED DESCRIPTION OF THE INVENTION 1 is that: the pre-treatment process of the spherical plain bearing described in Step 1 is as follows: polish the working surface of the inner ring of the spherical plain bearing with 400#, 800#, 1500# and 2000# sandpapers in sequence, then polish, and then ultrasonically clean in absolute ethanol for 15 minutes, and dry with a hair dryer. Others are the same as DETAILED DESCRIPTION OF THE INVENTION 1.

[0030] Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that in Step 1, the inner ring axis of the spherical plain bearing is fixed on the motor rotating shaft of the sample stage so that the two rotate coaxially. Others are the same as Embodiment 1 or 2.

[0031] Embodiment 4: The difference between this embodiment and Embodiment 3 is that in Step 1, the base vacuum during the magnetron sputtering process is 5×10 -3 Pa, the working gas is argon, the working pressure is 1 Pa, the bias voltage is 80 V, the sputtering frequency of the Ti target is 150 W, the sputtering time is 1 h, and the outer spherical surface of the inner ring of the spherical plain bearing is evenly coated with Ti coating material by using the sample stage motor. Others are the same as Embodiment 3.

[0032] Embodiment 5: The difference between this embodiment and Embodiment 4 is that in Step 2, the method for sealing and insulating the spherical plain bearing parts is as follows: Connect the aluminum wire led out from the anode of the micro-arc oxidation pulse power supply to the non-working surface of the inner ring of the spherical plain bearing with transparent tape and UV glue, and seal and insulate the non-working surface of the inner ring of the spherical plain bearing with transparent tape and UV glue so that the electrolyte only contacts the working surface of the inner ring. Others are the same as Embodiment 4.

[0033] Embodiment 6: The difference between this embodiment and Embodiment 5 is that in Step 2, the cathode in the micro-arc oxidation is a cast iron ring, and the pulse power supply adopts a constant current mode. Others are the same as Embodiment 5.

[0034] Embodiment 7: The difference between this embodiment and Embodiment 6 is that in Step 2, the parameter settings of the pulse power supply are as follows: the positive voltage is 590 V, the negative voltage is 200 V, the current density is 5 A / dm 2 , the frequency is 1000 Hz, the positive duty cycle is 50%, the negative duty cycle is 0%, and the oxidation duration is 25 s. Others are the same as Embodiment 6.

[0035] Embodiment 8: The difference between this embodiment and Embodiment 7 is that in Step 2, the concentrations of the solutes in the electrolyte are as follows: Na3PO4·12H2O is 8.67 g / L, Na2SiO3·9H2O is 9.34 g / L, NaF is 1 g / L, and the solvent is deionized water. Others are the same as Embodiment 7.

[0036] Embodiment 9: The difference between this embodiment and Embodiment 8 is that in Step 3, both the CoCrFeNi target and the Ti target are used as cathodes during the magnetron sputtering process. Others are the same as Embodiment 8.

[0037] Embodiment 10: The difference between this embodiment and Embodiment 9 is that: the background vacuum of the magnetron sputtering in Step 3 is 5×10 -3 Pa, the working pressure is 1 Pa, the bias voltage is 80 V, the sputtering frequency of the CoCrFeNi target is 100 W, the sputtering frequency of the Ti target is 150 W, and the sputtering time is 1.5 h. Others are the same as Embodiment 9.

[0038] The present invention is verified by the following tests:

[0039] Test 1: This test is a method for preparing a high-strength wear-resistant composite coating on the surface of a spherical plain bearing, and specifically is carried out according to the following steps:

[0040] 1. Fix the spherical plain bearing parts after pretreatment in the vacuum chamber of the magnetron sputtering equipment as the anode, use the Ti target as the cathode for magnetron sputtering, and prepare a Ti coating on the outer surface of the working surface of the inner ring of the spherical plain bearing;

[0041] The material of the spherical plain bearing is non-valve metal 42CrMo, and its structure is as Figure 1 shown, 1 is the outer ring, and 2 is the inner ring;

[0042] The pretreatment process of the spherical plain bearing is: polish the working surface of the inner ring of the spherical plain bearing with 400#, 800#, 1500# and 2000# sandpapers in sequence, then polish, and then ultrasonically clean in absolute ethanol for 15 min, and dry with a hair dryer;

[0043] Fix the axis of the inner ring of the spherical plain bearing on the motor rotating shaft of the sample stage to make the two rotate coaxially;

[0044] The background vacuum in the magnetron sputtering process is 5×10 -3 Pa, the working gas is argon, the working pressure is 1 Pa, the bias voltage is 80 V, the sputtering frequency of the Ti target is 150 W, the sputtering time is 1 h, and the outer spherical surface of the inner ring of the spherical plain bearing is evenly coated with Ti coating material by using the sample stage motor;

[0045] 2. After the spherical plain bearing parts with the Ti coating on the surface obtained in Step 1 are subjected to sealant insulation treatment, suspend them in the micro-arc oxidation electrolyte as the anode for micro-arc oxidation to obtain a titanium dioxide ceramic film on the Ti film;

[0046] The method for the spherical plain bearing parts to be subjected to sealant insulation treatment in Step 2 is: as Figure 2 shown (the outer ring of the spherical plain bearing is removed for more intuitive photographing, and only the inner ring is shown in the figure), connect the aluminum wire 6 led out from the anode of the micro-arc oxidation pulse power supply to the non-working surface of the inner ring of the spherical plain bearing with transparent tape 4 and UV glue 5, and seal and insulate the non-working surface of the inner ring of the spherical plain bearing with transparent tape 4 and UV glue 5 so that the electrolyte only contacts the working surface 3 of the inner ring;

[0047] In the micro-arc oxidation described in Step 2, the cathode is a cast iron ring. The pulse power supply adopts a constant current mode. The parameter settings of the pulse power supply are: the positive voltage is 590V, the negative voltage is 200V, the current density is 5A / dm 2 , the frequency is 1000Hz, the positive duty cycle is 50%, the negative duty cycle is 0%, and the oxidation duration is 25s;

[0048] The concentrations of the solutes in the electrolyte described in Step 2 are as follows: Na3PO4·12H2O is 8.67g / L, Na2SiO3·9H2O is 9.34g / L, NaF is 1g / L, and the solvent is deionized water;

[0049] III. After cleaning the surface of the specimen obtained in Step 2, put it into the magnetron sputtering vacuum chamber again, and magnetron sputter to prepare a CoCrFeNiTi high-entropy coating on the micro-arc oxidation layer to form a three-layer composite coating;

[0050] In the magnetron sputtering described in Step 3, a CoCrFeNi target and a Ti target are used together as the cathode;

[0051] The background vacuum of the magnetron sputtering described in Step 3 is 5×10 -3 Pa, the working pressure is 1Pa, the bias voltage is 80V, the sputtering frequency of the CoCrFeNi target is 100W, the sputtering frequency of the Ti target is 150W, and the sputtering time is 1.5h.

[0052] The operations of magnetron sputtering in Steps 1 and 3 include the following steps:

[0053] 1) Turn on the magnetron sputtering instrument and open the air release valve;

[0054] 2) After opening the vacuum chamber, fix the joint bearing part on the sample stage rotating fixture on the anode target, and at the same time place the cathode into the cathode target material;

[0055] 3) Turn on the air pump and gas cylinder, and turn on the chiller to ensure the stable operation of the equipment;

[0056] 4) After closing the chamber door, turn on the mechanical pump and the bypass valve to extract vacuum, and then turn on the molecular pump to ensure the vacuum degree in the vacuum chamber;

[0057] 5) After turning on the MPC power supply of the cathode target, open the intake valve to flush in argon;

[0058] 6) When the gate opening degree shows 200%, close the M plate valve to control the working gas flow;

[0059] 7) Adjust the voltage power and apply the bias voltage;

[0060] 8) Open the baffle of the cathode target material, start the rotation of the sample stage, ensure uniform coating of the bearing part, and start coating;

[0061] 9) After the coating is completed, turn off the above-mentioned devices in sequence and then take out the sample.

[0062] Comparative experiment: This experiment is a preparation method of CoCrFeNiTi composite coating without micro-arc oxidation bottom layer, and the specific steps are as follows:

[0063] Fix the pretreated joint bearing parts in the vacuum chamber of the magnetron sputtering equipment as the anode, use the CoCrFeNi target and Ti target together as the cathode for magnetron sputtering, and prepare a CoCrFeNiTi high-entropy coating on the outer surface of the working surface of the inner ring of the joint bearing;

[0064] The material of the said joint bearing is non-valve metal 42CrMo;

[0065] The pretreatment process of the said joint bearing is as follows: polish the working surface of the inner ring of the joint bearing with 400#, 800#, 1500# and 2000# sandpapers in sequence, then polish, and then ultrasonically clean in absolute ethanol for 15 min, and dry with a hair dryer;

[0066] Fix the axis of the inner ring of the joint bearing on the motor rotating shaft of the sample stage to make the two rotate coaxially;

[0067] The background vacuum of the said magnetron sputtering is 5×10 -3 Pa, the working pressure is 1 Pa, the bias voltage is 80 V, the sputtering frequency of the CoCrFeNi target is 100 W, the sputtering frequency of the Ti target is 150 W, and the sputtering time is 1.5 h.

[0068] Figure 3 It is a comparison chart of the friction coefficient curves of the CoCrFeNiTi composite coating with micro-arc oxidation bottom layer prepared in Experiment 1 and the CoCrFeNiTi composite coating without micro-arc oxidation bottom layer prepared in the comparative experiment. The tribological test is carried out on a standard friction and wear test equipment (model: MPT-3G). The pin-disc friction pair is loaded on the equivalent plane part of the joint bearing. The bearing is fixed and the pin-disc is the friction pair that rotates. The tribological performance of the equivalent plane part of the bearing is tested to obtain Figure 2 The comparison result of the tribological curves shown. Among them, the average value of the tribological coefficient of the film without bottom layer is 0.561, and the average value of the tribological coefficient of the Ti film with micro-arc oxidation bottom layer is 0.416. The friction coefficient is significantly reduced and the wear resistance is well improved.

[0069] Figure 4SEM comparison images of the CoCrFeNiTi composite coating with a micro-arc oxidation bottom layer prepared in Experiment 1 and the CoCrFeNiTi composite coating without a micro-arc oxidation bottom layer prepared in the comparative experiment after the above friction and wear experiments. The left figure shows the micro-arc oxidation bottom film of the Ti film. It can be seen that the peeling of the high-entropy film is not obvious, and the substrate is not exposed at the bottom layer. However, obvious substrate exposure occurs in the right figure of the film without the bottom layer (the Fe element is the main element of 42CrMo), indicating that the friction and wear experiment has damaged the parts and cannot effectively improve the performance of the bearing.

[0070] The present invention adopts the above method for preparing a high-strength wear-resistant composite coating on the surface of a spherical plain bearing, which complements the advantages of magnetron sputtering technology and micro-arc oxidation technology, and obtains a composite coating with excellent wear resistance, which can effectively protect the bearing in extreme environments and greatly improve its service life.

Claims

1. A method for preparing a high-strength wear-resistant composite coating on the surface of a spherical bearing, characterized in that The preparation method of the high-strength wear-resistant composite coating on the surface of the spherical bearing is carried out according to the following steps:

1. Fix the pre-treated spherical plain bearing parts in the vacuum chamber of the magnetron sputtering equipment, use the Ti target as the cathode for magnetron sputtering, and prepare the Ti coating on the outer surface of the working surface of the inner ring of the spherical plain bearing; The material of the spherical bearing is non-valve metal 42CrMo; The background vacuum during the magnetron sputtering process is 5×10 -3 Pa, the working gas is argon, the working gas pressure is 1Pa, the bias voltage is 80V, the sputtering frequency of the Ti target is 150W, the sputtering time is 1h, the inner ring axis of the spherical plain bearing is fixed on the motor shaft of the sample stage so that the two rotate coaxially, and the outer spherical surface of the inner ring of the spherical plain bearing is evenly coated with the Ti coating material by the motor of the sample stage; 2. The spherical bearing parts with Ti coating on the surface obtained in step 1 are placed in a micro-arc oxidation electrolyte as an anode for micro-arc oxidation after sealing and insulation treatment, so as to obtain a titanium dioxide ceramic film on the Ti film; The concentrations of the solutes in the electrolyte are as follows: Na3PO4·12H2O is 8.67 g / L, Na2SiO3·9H2O is 9.34 g / L, NaF is 1 g / L, and the solvent is deionized water; 3. After cleaning the surface of the test piece obtained in step 2, it is placed in the magnetron sputtering vacuum chamber again. During the magnetron sputtering process, the CoCrFeNi target and the Ti target are used together as cathodes to prepare the CoCrFeNiTi high entropy coating on the micro-arc oxide layer by magnetron sputtering to form a three-layer composite coating.

2. The method for preparing a high-strength wear-resistant composite coating on a spherical bearing surface according to claim 1, characterized in that The pretreatment process of the spherical bearing described in step 1 is: grind the working surface of the inner ring of the spherical bearing with 400#, 800#, 1500# and 2000# sandpaper in turn, then polish it, then ultrasonically clean it in anhydrous ethanol for 15 minutes, and blow dry it with a hair dryer.

3. The method for preparing a high-strength wear-resistant composite coating on a joint bearing surface according to claim 1, characterized in that The method for sealing and insulating the spherical bearing parts in step 2 is: use transparent tape and UV glue to connect the aluminum wire led out of the anode of the micro-arc oxidation pulse power supply to the non-working surface of the inner ring of the spherical bearing, and use transparent tape and UV glue to seal and insulate the non-working surface of the inner ring of the spherical bearing so that the electrolyte only contacts the working surface of the inner ring.

4. The method for preparing a high-strength wear-resistant composite coating on a spherical bearing surface according to claim 1, characterized in that The cathode in the micro-arc oxidation described in step 2 is a cast iron ring, and the pulse power supply adopts a constant current mode.

5. The method for preparing a high-strength wear-resistant composite coating on a spherical bearing surface according to claim 4, characterized in that The parameters of the pulse power supply described in step 2 are set to positive voltage of 590V, negative voltage of 200V, and current density of 5A / dm 2 , frequency is 1000Hz, positive duty cycle is 50%, negative duty cycle is 0%, and oxidation time is 25s.

6. The method for preparing a high-strength wear-resistant composite coating on a spherical bearing surface according to claim 1, characterized in that The background vacuum of the magnetron sputtering described in step 3 is 5×10 -3 Pa, the working gas pressure is 1Pa, the bias voltage is 80V, the sputtering frequency of the CoCrFeNi target is 100W, the sputtering frequency of the Ti target is 150W, and the sputtering time is 1.5h.

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