A high-entropy alloy composite coating, a hydraulic pump motor friction pair adopting the coating and a preparation method thereof

Abstract

The application belongs to the technical field of hydraulic pump motor manufacturing, and particularly relates to a high-entropy alloy composite coating, a hydraulic pump motor friction pair adopting the coating and a preparation method thereof. 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 , and the thickness is 180-220 nm; the transition layer is (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 , and the thickness is 700-750 nm; and the friction-reducing layer is (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 , and the thickness is 700-750 nm. The coating forms a uniform and dense structure on the surface of the friction pair, has high hardness and excellent wear resistance, can effectively reduce the wear of the hydraulic pump motor friction pair, and prolong the service life.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydraulic pump motor manufacturing, and particularly relates to a high-entropy alloy composite coating, a hydraulic pump motor friction pair adopting the coating and a preparation method thereof. BACKGROUND

[0002] As the core component of the hydraulic transmission system, the hydraulic pump motor bears the important function of converting mechanical energy and hydraulic energy. The performance of the key friction pair of the pump motor directly affects the efficiency, service life and reliability of the hydraulic pump motor. According to the analysis of the working principle of the hydraulic pump motor, there is relative motion between the cylinder body and the plunger, the sliding shoe and the swash plate, the cylinder body and the distribution plate, and the ball hinge and the return plate in the internal components of the hydraulic pump motor, which constitutes the key friction pair inside the plunger pump. The gap between each pair of friction pairs is very small. Although the oil lubrication exists between each pair of friction pairs, the contaminated particles in the oil and the impact load can cause wear between the friction pairs, increase the internal leakage, reduce the volumetric efficiency and mechanical efficiency of the pump motor, and is one of the main reasons for the failure and fault of the pump motor.

[0003] In order to improve the performance of the friction pair of the hydraulic pump motor, the existing researches continue to explore the application of new materials and coating technologies. For example, using high-performance materials (such as copper alloy, nitrided steel) to manufacture friction pair components can improve their wear resistance, corrosion resistance and high temperature stability. In addition, using advanced coating technology (such as diamond-like carbon film, solid lubrication coating) can improve the lubrication and friction characteristics, reduce wear and heat.

[0004] High-entropy alloy is a new type of material, which is composed of multiple elements and the molar ratio of elements is close to or equal. Compared with traditional alloys, high-entropy alloy has higher entropy, which makes its crystal structure more uniform and stable. High-entropy alloy has excellent mechanical properties, wear resistance, corrosion resistance, high temperature stability and mechanical properties, and has wide application potential.

[0005] As a surface modification method, coating technology plays an important role in improving material properties and increasing surface functionality. Traditional coating technologies include physical vapor deposition and chemical vapor deposition, which have been widely used. High-entropy alloy coating technology uses high-entropy alloy materials to prepare coatings based on coating technology to further improve coating performance. In recent years, technical research has begun to explore the application of high-entropy alloy materials in the coating field to break through the bottleneck of existing coating technology. The development of this technology has received widespread attention from academia and industry. Faced with the application needs of increasingly demanding material performance, durability, and reliability, high-entropy alloy coating technology has great potential and appeal. By preparing high-entropy alloy coatings, uniform and dense films can be formed on the surfaces of key components, providing additional protection and functionality for products, improving their wear resistance, corrosion resistance, high-temperature stability, and mechanical properties, and meeting the requirements of various applications.

[0006] At present, the key friction pairs of hydraulic pumps and motors widely adopt the nitriding-bimetallic casting (molten copper) matching processing technology, such as the inclined plate (nitriding)-slipper (molten copper), plunger (nitriding)-plunger hole (molten copper), and distribution plate (nitriding)-cylinder body (molten copper). A hard (nitriding) and soft (molten copper) friction pair matching mechanism is used. The nitriding process mainly improves the hardness and wear resistance of the friction pair, and the bimetallic casting process improves the friction performance and lubrication performance of the friction pair, comprehensively improving the overall wear resistance and service life of the paired friction pairs.

[0007] One of the main drawbacks of nitriding technology is the weak adhesion of the nitride layer, which is prone to peeling or flaking. In addition, the nitriding process requires strict control of parameters such as temperature, atmosphere, and treatment time to ensure the uniformity and quality of the nitride layer, which increases the complexity and cost of process control.

[0008] One of the main drawbacks of bimetallic casting technology is the difficulty in ensuring the quality of the interfacial bonding between the two metals during the casting process. Poor interfacial bonding can lead to delamination, cracks, or material inhomogeneity, thereby degrading the performance of the friction pair. Furthermore, bimetallic casting requires precise control of casting process parameters, including temperature, pouring speed, and cooling method, to ensure the quality and performance of the composite material.

[0009] Under the high pressure, high speed and alternating load conditions of high-end hydraulic pumps and motors, the friction pairs using nitride-molten copper surface treatment technology often suffer from copper layer peeling, wear, nitride layer peeling, heat accumulation and ablation due to insufficient friction reduction and wear resistance, resulting in reduced pump and motor operating efficiency and even destructive failure. Summary of the Invention

[0010] The existing friction pair surface treatment technology (mainly nitrogenization and bimetallic casting) cannot meet the service requirements of high-pressure large-displacement high-end hydraulic pump motor products, and the technical bottleneck and industry problem of restricting the service life of the products are proposed. A kind of high-entropy alloy coating suitable for the surface of key friction pair of hydraulic pump motor, which has high wear resistance, high toughness and high thermal stability, and a preparation method of the coating material, which is environmentally friendly, simple in steps, low in cost and has industrialization popularization value.

[0011] To solve the above problems, the present application provides a high-entropy alloy composite coating material suitable for the friction pair of a hydraulic pump motor.

[0012] A high-entropy alloy composite coating, the composite coating comprises a primer layer, a transition layer, a friction-reducing layer, as shown in Figure 1 The primer layer is Al 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 , the transition layer is (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 , and the friction-reducing layer is (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 .

[0013] The composition of the primer layer is Al 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 , and the thickness is about 180-220nm, which is used to improve the bonding strength between the coating and the substrate and prevent the coating from falling off during friction.

[0014] The composition of the transition layer is (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 , and the thickness is about 700-750nm, which is used to reduce the overall stress of the coating and improve the toughness and impact resistance of the coating.

[0015] The composition of the friction-reducing layer is (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C0.05 The thickness is about 700-750nm, good wear resistance is provided for the friction pair, the wear and heat of the friction pair during work are effectively reduced, and the service life is improved.

[0016] The friction pair of the hydraulic pump motor is a plunger, a flow distribution disc, a swash plate and a ball hinge, and the material is generally alloy steel after nitriding treatment, such as 42CrMo, 31CrMoV9, 38CrMoAlA and the like.

[0017] The friction pair of the friction pair, such as the plunger-plunger hole, the flow distribution disc-cylinder body, the swash plate-slipper and the ball hinge-return disc, also uses alloy steel after nitriding treatment, such as 42CrMo, 31CrMoV9, 38CrMoAlA and the like.

[0018] The coating is applied to the surface of the plunger, the flow distribution disc, the swash plate and the ball hinge, and forms a friction pair with the nitriding alloy steel, replaces the original nitriding-copper melting friction pair, compared with the prior art, the friction pair with the coating has better wear resistance and longer service life.

[0019] The application provides a preparation method of a high-entropy alloy composite coating.

[0020] The temperature is increased to 300-350 DEG C, the bias voltage is set to 250V-300V, the magnetron sputtering ion source is opened, the alloy target material is excited, metal element deposition is carried out, the voltage is set to 1600V-1800V, the current is set to 10A-15A, 30min film deposition is carried out, and Al 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 The bottom layer is prepared.

[0021] The bias voltage is set to 150V-200V, the magnetron sputtering ion source is opened, the alloy target material is excited, metal element deposition is carried out, the voltage is set to 1600V-1800V, the current is set to 12A-14A, nitrogen gas with a flow of 12-15sccm is input, 4h film deposition is carried out, and (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 The transition layer is prepared.

[0022] After heating to 500-550℃; set the bias voltage to 300V-350V, turn on the magnetron sputtering ion source, excite the alloy target, and deposit the metal element. The voltage is set to 1600V-1800V and the current is set to 12A-14A. At the same time, turn on the pulse arc ion source to excite the graphite target. The voltage is set to 250-350V and the pulse frequency is set to 1-10Hz. Keep the two ion sources turned on for 4 hours to complete (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 Preparation of anti-friction layer.

[0023] The present invention provides a method for preparing a high entropy alloy coating, the specific steps of which are as follows:

[0024] (1) Immerse the friction pair parts in anhydrous ethanol and perform ultrasonic vibration cleaning for 10 minutes to remove oil, dust and impurities on the surface of the parts.

[0025] (2) Then immerse the parts in pure water and perform ultrasonic vibration for 10 minutes to remove the anhydrous ethanol residue on the surface of the parts. After cleaning, place the parts in a 50°C drying oven for drying for 30-60 minutes.

[0026] (3) Clamp the parts onto the fixture and place them into the vacuum chamber of the vacuum coating equipment. Close the vacuum chamber door and pump the air pressure to 2*10 -2 Below Pa.

[0027] (4) Turn on the tooling turret, introduce high-purity argon gas to keep the vacuum chamber pressure constant at 0.1 Pa, turn on the anode layer ion source to perform ion cleaning on the parts, with a voltage of 700V-1000V, and continue for 10-15 minutes.

[0028] (5) Turn on the heater and wait for the vacuum chamber to heat up to 300-350℃.

[0029] (6) Turn on the bias power supply and set the voltage to 250V-300V.

[0030] (7) Turn on the magnetron sputtering ion source, excite the alloy target, and deposit the metal element. Set the voltage to 1600V-1800V and the current to 10A-15A for 30 minutes of thin film deposition to complete the Al 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 Preparation of base layer.

[0031] (8) Set the bias voltage to 150V-200V. Turn on the magnetron sputtering ion source, excite the alloy target material, deposit the metal elements, set the voltage to 1600V-1800V, set the current to 12A-14A, and pass in 12-15sccm of nitrogen gas. Perform thin film deposition for 4 hours to complete the (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 Transition layer preparation.

[0032] (9) Set the heater to 500-550℃ and wait for the temperature to rise to the specified temperature.

[0033] (10) Set the bias voltage to 300V-350V. Turn on the magnetron sputtering ion source, excite the alloy target material, deposit the metal elements, set the voltage to 1600V-1800V, set the current to 12A-14A, and turn on the pulsed arc ion source, excite the graphite target material, set the voltage to 250-350V, set the pulse frequency to 1-10Hz, and keep both ion sources on for 4 hours to complete the (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 Friction-reducing layer preparation.

[0034] The application also provides the use of the high-entropy alloy composite coating described above in a hydraulic pump motor friction pair.

[0035] The application also provides a hydraulic pump motor friction pair using the high-entropy alloy composite coating described above.

[0036] The application also provides a method for preparing a hydraulic pump motor friction pair, comprising the following steps:

[0037] After cleaning and drying the hydraulic pump motor friction pair parts, place them in the vacuum chamber of the vacuum coating equipment, raise the temperature to 300-350℃, and set the bias voltage to 250V-300V. Turn on the magnetron sputtering ion source, excite the alloy target material, deposit the metal elements, set the voltage to 1600V-1800V, set the current to 10A-15A, and perform thin film deposition for 30min to complete the Al 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 Bottom layer preparation;

[0038] Set the bias voltage to 150V-200V; turn on the magnetron sputtering ion source, excite the alloy target, and deposit the metal element. Set the voltage to 1600V-1800V, the current to 12A-14A, and introduce nitrogen with a flow rate of 12-15sccm. Deposition of the film was carried out for 4 hours to complete (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 Preparation of transition layer;

[0039] After heating to 500-550℃; set the bias voltage to 300V-350V, turn on the magnetron sputtering ion source, excite the alloy target, and deposit the metal element. The voltage is set to 1600V-1800V and the current is set to 12A-14A. At the same time, turn on the pulse arc ion source to excite the graphite target. The voltage is set to 250-350V and the pulse frequency is set to 1-10Hz. Keep the two ion sources turned on for 4 hours to complete (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 Preparation of anti-friction layer.

[0040] Furthermore, the cleaning step includes: immersing the friction pair parts in anhydrous ethanol and performing ultrasonic vibration cleaning for 8 to 12 minutes, and then immersing the friction pair parts in pure water and performing ultrasonic vibration for 8 to 12 minutes to remove the anhydrous ethanol residue on the surface of the parts.

[0041] Furthermore, after cleaning, the parts are placed in a drying oven at 45-55°C for drying for 30-60 minutes.

[0042] Furthermore, the parts are clamped on the fixture and placed in the vacuum chamber of the vacuum coating equipment. The vacuum chamber door is closed and the air pressure is pumped to 2*10 -2 Below Pa.

[0043] Furthermore, before applying the coating, high-purity argon gas is introduced to keep the vacuum chamber pressure constant at 0.1 Pa, and the anode layer ion source is turned on to perform ion cleaning on the parts at a voltage of 700V-1000V for 10-15 minutes.

[0044] Furthermore, the coating is applied to the surfaces of the plunger, the distribution plate, the inclined plate, and the ball joint, forming a dual pair with the nitrided alloy steel.

[0045] Beneficial effects

[0046] High-entropy alloys (HEAs) offer high hardness, high wear resistance, and excellent tribological properties. HEAs coatings produced using magnetron sputtering technology can form a uniform, dense structure on the friction pair surface. These coatings, with their high hardness and excellent wear resistance, can effectively reduce wear on the friction pair of hydraulic pumps and motors, extending their service life.

[0047] Pulsed arc coupled with magnetron sputtering was used to deposit multi-element doped high entropy alloy composite coating: AlCrMoSiNb—(AlCrMoSiNb)N 0.05 —(AlCrMoSiNb)C 0.05 , taking advantage of the small size of nitrogen atoms and their easy combination with metal elements, they are doped into the gaps between the metal elements in the high-entropy alloy material, thereby reducing the stress of the coating and improving the overall toughness; carbon atoms are used to form carbide structures with the metal elements in the alloy. These carbides have high hardness and wear resistance, which improves the wear resistance of the parts surface. At the same time, carbon elements can improve the self-lubricating properties of the coating, effectively reduce the friction coefficient, and reduce wear and heat.

[0048] Applying a high-entropy alloy wear-resistant coating to the friction pair of a hydraulic pump or motor improves friction performance compared to friction pairs fabricated using the traditional nitriding-bimetallic casting process, extending product life. This coating preparation process can replace the nitriding-bimetallic casting process, offering an environmentally friendly, streamlined, and low-cost friction pair surface enhancement technology with potential for industrial application.

[0049] The present invention develops a multi-element doped high-entropy alloy composite coating, which is applied to the key friction pair surfaces of hydraulic pumps and motors. It can effectively improve the friction performance of the friction pairs and increase their service life. The preparation cost is lower than the bimetallic casting and copper melting process.

[0050] The high-entropy alloy coating is prepared by magnetron sputtering and pulse arc coupling technology, carbon doping is used to improve the self-lubricating properties of the coating, and the carbide phase is used to improve the hardness and wear resistance of the coating. Compared with nitriding-molten copper, the friction coefficient is reduced by more than 80%.

[0051] The present invention adopts magnetron sputtering and pulse arc coupling technology in a high vacuum environment (<0.04Pa) to prepare a multi-element doped high-entropy alloy composite coating on the surface of the key friction pair of the hydraulic pump motor, replacing the traditional nitriding-melting copper technology, improving the wear resistance, high-temperature stability and mechanical properties of the friction pair, reducing the processing cost of the friction pair, and improving the comprehensive service performance of the friction pair. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Schematic diagram of a hydraulic pump-motor friction pair using high-entropy alloy coating.

[0053] Figure 2This is the friction coefficient curve of the high entropy alloy coating friction pair and the nitriding-molten copper friction pair.

[0054] Figure 3 These are the hardness test results of high entropy alloy coated friction pairs and nitrided friction pairs.

[0055] Figure 4 The surface morphology of a hydraulic motor ball joint coated with a high-entropy alloy coating and a nitrided hydraulic motor ball joint after 3000 impact tests. Figure (a) shows the pressure-time curve of the hydraulic motor impact test, Figure (b) shows the surface morphology of a 42CrMo ball joint coated with the composite high-entropy alloy coating of the invention after 3000 start-stop impacts, Figure (c) shows the surface morphology of a 42CrMo ball joint coated with a single layer of high-entropy alloy, Figure (d) shows the surface morphology of a nitrided 42CrMo ball joint under the same test conditions, and Figure (e) shows the surface morphology of a nitrided QT-600 ball joint under the same test conditions. DETAILED DESCRIPTION

[0056] Example 1

[0057] Figure 1 This diagram shows a hydraulic pump and motor friction pair using a high-entropy alloy coating. This design is applicable to the three key friction pairs in hydraulic pumps and motors: plunger-plunger bore, valve plate-cylinder block, swash plate-slipper, and ball joint-return plate. This replaces the existing nitrided-bimetallic cast pairing, pairing high-entropy coating with nitrided alloy steel, resulting in significantly superior wear resistance and service life. Implementation Example:

[0058] (1) Place the plunger pump plunger after nitriding of 31CrMoV9 into an ultrasonic cleaning machine, add anhydrous ethanol to immerse the plunger, and then perform ultrasonic vibration cleaning for 10 minutes to remove oil, dust and impurities on the surface of the plunger.

[0059] (2) Place the plunger after alcohol cleaning in another ultrasonic cleaning machine with a clamp, add deionized water to immerse the plunger, and perform ultrasonic vibration for 10 minutes to remove the anhydrous ethanol residue on the surface of the part. After cleaning, place the plunger in a 50°C drying oven for drying for 30 minutes.

[0060] (3) Clamp the dried plunger onto the fixture and place it into the vacuum chamber of the vacuum coating equipment. Close the vacuum chamber door and pump the air pressure to 2*10 -2 Below Pa.

[0061] (4) Turn on the tooling turret, introduce high-purity argon gas to keep the vacuum chamber pressure constant at 0.1 Pa, turn on the anode layer ion source to perform ion cleaning on the parts, the voltage is 800 V, and the duration is 10 minutes.

[0062] (5) Turn on the heater and wait for the vacuum chamber to heat up to 300°C.

[0063] (6) Turn on the bias power supply and set the voltage to 300V.

[0064] (7) Turn on the magnetron sputtering ion source, excite the alloy target, and deposit the metal element. Set the voltage to 1700V and the current to 10A for 30 minutes of thin film deposition to complete the Al 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 Preparation of base layer.

[0065] (8) Set the bias voltage to 200V. Turn on the magnetron sputtering ion source, excite the alloy target, and deposit the metal element. Set the voltage to 1700V, the current to 12A, and introduce nitrogen with a flow rate of 12sccm. Deposit the film for 4 hours to complete (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 Preparation of transition layer.

[0066] (9) Set the heater to 500°C and wait for the temperature to rise to the specified temperature.

[0067] (10) Set the bias voltage to 350V, turn on the magnetron sputtering ion source, excite the alloy target, and perform metal element deposition. The voltage is set to 1700V and the current is set to 12A. At the same time, turn on the pulse arc ion source to excite the graphite target. The voltage is set to 280V and the pulse frequency is set to 5Hz. Keep the two ion sources turned on for 4 hours to complete (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 Preparation of anti-friction layer.

[0068] (11) The bimetallic casting process is eliminated for the plunger hole that is worn against the plunger, and a nitrided substrate is directly used, which saves costs and avoids the problem of peeling caused by the difficulty in quality control of the copper layer. At the same time, the overall wear resistance and impact resistance of the friction pair are improved, thereby extending the service life.

[0069] Figure 2The following are the friction coefficient curves for a high-entropy alloy-coated friction pair and a nitriding-molten copper friction pair. The test conditions were: a normal load of 1800N, a velocity of 5cm / s, and the test environment was with the specimens immersed in No. 46 hydraulic oil. The results show that within the initial 500 seconds, the friction coefficient of the nitriding-molten copper test pair increased from 0.05 to approximately 0.4, indicating that the oil film between the friction pairs stabilized only after 500 seconds. The friction coefficient of the high-entropy alloy test pair remained stable between 0.05 and 0.1, representing a reduction of over 80% compared to the nitriding-molten copper test pair, indicating a faster and more stable oil film.

[0070] Figure 3 The hardness test results of the high-entropy alloy coating friction pair and the nitrided friction pair are shown in the figure. The high-entropy alloy coating substrate is 42CrMo quenched and tempered alloy steel. Due to the thin thickness of the coating (about 1.5 to 2μm), its hardness was measured by nanoindentation. The nitrided friction pair material is also 42CrMo quenched and tempered alloy steel, and the hardness was measured using a conventional Vickers hardness tester. The measurement results are shown in the figure. The hardness of the high-entropy alloy coating is 1836Hv, and the hardness of the nitrided friction pair is 823Hv. Compared with the nitrided friction pair, the friction pair coated with the high-entropy alloy coating has a super high hardness and can provide better wear resistance when the hydraulic pump motor is working.

[0071] Figure 4 The surface morphology of the hydraulic motor ball joint coated with high entropy alloy and the nitrided hydraulic motor ball joint after 3000 impact tests. Figure 4 (a) is the pressure-time curve of the hydraulic motor impact test. This test simulates the start-stop action of the excavator during operation and is used to accurately detect the service reliability of the friction pair under start-stop impact conditions. Figure 4 (b) is the surface morphology of the ball joint coated with high entropy alloy after 3000 start-stop shocks. Figure 4 (c) Under the same test conditions, a single-layer anti-friction layer (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 The surface morphology of the spherical joint, Figure 4 (d) is the surface morphology of nitrided 42CrMo ball joint under the same test conditions. Figure 4(e) shows the surface morphology of a nitrided QT-600 ball joint under the same test conditions. As shown in the figure, after 3000 start-stop shock cycles under the same test conditions, the ball joint coated with the composite high-entropy alloy coating showed no wear and no coating detachment. The ball joint coated with a single layer of high-entropy alloy coating showed no wear, but the coating detached. This was due to the lack of a primer and transition layer, resulting in insufficient coating adhesion, which led to coating detachment under high-speed and heavy-load conditions. The surfaces of the nitrided 42CrMo and nitrided QT-600 ball joints showed ablation and wear morphologies. The surface friction coefficient of the high-entropy alloy-coated ball joint is lower than that of nitrided steel and nitrided ductile iron ball joints, and its hardness is much higher than that of nitrided steel and nitrided ductile iron ball joints. Therefore, under high-speed and heavy-load conditions, the high-entropy alloy coating can effectively reduce wear and heat generation, preventing wear and erosion of the friction pair. Furthermore, the composite coating described herein incorporates a primer and transition layer in its structural design, effectively improving the adhesion between the coating and the substrate and ensuring that the coating will not detach under harsh operating conditions.

Claims

1. A high entropy alloy composite coating, characterized in that: It includes a primer layer, a transition layer, and a friction reducing layer. The primer layer is Al 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 , with a thickness of 180-220nm; the transition layer is (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 , with a thickness of 700-750nm; the anti-friction layer is (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 , with a thickness of 700-750nm.

2. The method for preparing a high entropy alloy composite coating according to claim 1, wherein: The following steps are involved: Raise the temperature to 300-350℃, set the bias voltage to 250V-300V; turn on the magnetron sputtering ion source, excite the alloy target, and deposit the metal element. Set the voltage to 1600V-1800V and the current to 10A-15A for 30 minutes of thin film deposition to complete the Al 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 Preparation of base layer; Set the bias voltage to 150V-200V; Turn on the magnetron sputtering ion source, excite the alloy target, and deposit the metal element. Set the voltage to 1600V-1800V, the current to 12A-14A, and introduce nitrogen with a flow rate of 12-15sccm. Deposit the film for 4 hours to complete (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 Preparation of transition layer; After heating to 500-550℃; set the bias voltage to 300V-350V, turn on the magnetron sputtering ion source, excite the alloy target, and deposit metal elements. The voltage is set to 1600V-1800V and the current is set to 12A-14A. At the same time, turn on the pulse arc ion source to excite the graphite target. The voltage is set to 250-350V and the pulse frequency is set to 1-10Hz. Keep the two ion sources turned on for 4 hours to complete. (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 Preparation of anti-friction layer.

3. Application of the high entropy alloy composite coating according to claim 1 in a friction pair of a hydraulic pump motor.

4. A hydraulic pump motor friction pair, characterized in that: The high entropy alloy composite coating according to claim 1 is used.

5. A method for preparing a hydraulic pump motor friction pair, characterized in that: The following steps are involved: After cleaning and drying the friction pair parts of the hydraulic pump and motor, place them in the vacuum chamber of the vacuum coating equipment, raise the temperature to 300-350℃, set the bias voltage to 250V-300V; turn on the magnetron sputtering ion source, excite the alloy target, and deposit metal elements. Set the voltage to 1600V-1800V and the current to 10A-15A for 30 minutes of thin film deposition to complete the Al 0.2 Cr 0.2 Mo 0.2 Si 0.2 Nb 0.2 Preparation of base layer; Set the bias voltage to 150V-200V; Turn on the magnetron sputtering ion source, excite the alloy target, and deposit the metal element. Set the voltage to 1600V-1800V, the current to 12A-14A, and introduce nitrogen with a flow rate of 12-15sccm. Deposit the film for 4 hours to complete (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )N 0.05 Preparation of transition layer; After heating to 500-550℃; set the bias voltage to 300V-350V, turn on the magnetron sputtering ion source, excite the alloy target, and deposit metal elements. The voltage is set to 1600V-1800V and the current is set to 12A-14A. At the same time, turn on the pulse arc ion source to excite the graphite target. The voltage is set to 250-350V and the pulse frequency is set to 1-10Hz. Keep the two ion sources turned on for 4 hours to complete. (Al 0.19 Cr 0.19 Mo 0.19 Si 0.19 Nb 0.19 )C 0.05 Preparation of anti-friction layer.

6. The method for preparing a hydraulic pump-motor friction pair according to claim 5, characterized in that: The cleaning step includes: immersing the friction pair parts in anhydrous ethanol and performing ultrasonic vibration cleaning for 8 to 12 minutes, and then immersing the friction pair parts in pure water and performing ultrasonic vibration for 8 to 12 minutes to remove anhydrous ethanol residue on the surface of the parts.

7. The method for preparing a hydraulic pump-motor friction pair according to claim 5, characterized in that: After cleaning, place the parts in a drying oven at 45-55°C for 30-60 minutes.

8. The method for preparing a hydraulic pump-motor friction pair according to claim 5, characterized in that: Clamp the parts onto the fixture and place them into the vacuum chamber of the vacuum coating equipment. Close the vacuum chamber door and pump the air pressure to 2*10 -2 Below Pa.

9. The method for preparing a hydraulic pump-motor friction pair according to claim 5, characterized in that: Before applying the coating, high-purity argon gas is introduced to keep the vacuum chamber pressure constant at 0.1 Pa, and the anode layer ion source is turned on to perform ion cleaning on the parts with a voltage of 700V-1000V for 10-15 minutes.

10. The method for preparing a hydraulic pump-motor friction pair according to claim 5, characterized in that: The coating is applied to the surfaces of the plunger, the distribution plate, the inclined plate and the ball joint, and forms a dual pair with the nitrided alloy steel.

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