Dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material and preparation method thereof

Abstract

The application discloses a dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material and a preparation method thereof, and belongs to the technical field of sputtering plating. The coating material has a multilayer and multi-component structure and is sequentially composed of a bonding layer, a transition layer and a self-lubricating functional layer; the bonding layer is a Cr layer, the transition layer is a CrN layer, and the self-lubricating functional layer is an Ag-Ag2CrO4 layer with dendritic microstructure prepared by compounding Ag and Ag2CrO4. The coating has good lubricity and can be used in a wide temperature range. The coating has hydrophobicity, good corrosion resistance and good oxidation resistance. The coating has good adhesion to a base material and excellent temperature resistance and wear resistance. The application further provides a preparation method of the coating material, and the production process is simple, efficient and easy for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of sputtering coating technology, and more particularly to a dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material and its preparation method. Background Technology

[0002] Wear failure is a common failure mode in engineering equipment, mechanical structures, and components made of metals and other materials, causing numerous safety accidents and economic losses annually. Solving the friction and wear problems of key components in engineering equipment and mechanical structures is crucial for their stable operation, extending their service life, adaptability to extreme environments, and reducing maintenance costs. Traditional lubrication technologies struggle to function stably in high-temperature environments. Liquid greases generally operate at temperatures below 300°C and are prone to localized decomposition and failure under extreme gravity, losing their lubricating properties. Furthermore, liquid greases release toxic gases during decomposition, posing harm to the environment and maintenance personnel. Residual liquid grease on component surfaces also complicates maintenance. Single-component solid lubricants represent another important technological direction for addressing friction and wear problems in key parts of engineering equipment and mechanical structures. Ag, a soft metal, is environmentally friendly, low-cost, and has minimal ecological hazards, making it a commonly used solid lubricant. Applying Ag to fasteners such as bolts to address sintering and seizing issues and reduce the coefficient of friction between friction pairs is already a mature technology. However, when the temperature exceeds 500℃ or in a humid environment, single-component solid lubricants are prone to losing their lubricating properties due to oxidation. In addition, single-component solid lubricants have low hardness and poor load-bearing capacity. At high temperatures, their softness increases rapidly, and when the thickness is high, plastic deformation causes solid lubricant material to transfer to the substrate and interface, resulting in high friction and wear, which limits their application in extreme environments.

[0003] Self-lubricating coating technology holds promise for solving the lubrication and friction reduction challenges of engineering equipment and mechanical structures in high-temperature environments. At high temperatures, the components of the self-lubricating coating gradually diffuse towards the friction interface, forming or undergoing in-situ oxidation to generate a lubricating phase at the interface. This lubricating phase forms a stable and continuous lubricating film at the friction interface, causing friction between components of engineering equipment and mechanical structures to occur within the lubricating film, thereby reducing the coefficient of friction and minimizing wear. Due to its high load-bearing capacity, ability to provide a high-quality lubricating film even at high temperatures, minimal corrosion to the friction interface, and good thermal and chemical stability, self-lubricating coating technology has received considerable attention since its inception. Self-lubricating coatings generally consist of three components: a substrate phase, a reinforcing phase, and a lubricating phase. These components work together to provide excellent tribological properties at high temperatures, as well as superior thermal and chemical stability. The substrate phase primarily bears the load and frictional wear; the lubricating phase provides good tribological properties at high temperatures; and the reinforcing phase improves the thermal stability and oxidation resistance of the self-lubricating coating. Current research on self-lubricating coatings mainly focuses on the compatibility between various substrate phases, lubricating phases, and reinforcing phases, as well as their tribological properties at different temperatures. There is still no self-lubricating coating that can work stably over a wide temperature range. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, in a first aspect of the present invention, a dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material with good temperature resistance, corrosion resistance and high bonding strength is provided. The coating material has a multi-layer and multi-component structure, consisting of a bonding layer, a transition layer and a self-lubricating functional layer in sequence; the bonding layer is a Cr layer, the transition layer is a CrN layer, and the self-lubricating functional layer is an Ag-Ag2CrO4 layer with a dendritic microstructure prepared by combining Ag and Ag2CrO4.

[0005] The design concept of this invention lies in simultaneously adding different lubricating phases to a self-lubricating coating, allowing their complementary properties to broaden the operating temperature range of the self-lubricating coating and achieve synergistic lubrication. A low-temperature lubricating phase and a high-temperature lubricating phase are added simultaneously to the self-lubricating coating. The low-temperature lubricating phase provides lubrication at lower temperatures, and the presence of the high-temperature lubricating phase increases the operating temperature of the low-temperature lubricating phase to some extent. The high-temperature lubricating phase is easily sheared at high temperatures, thus ensuring good lubricity of the self-lubricating coating even at higher temperatures. In this invention, Ag and Ag₂CrO₄ are used in combination, with Ag serving as the low-temperature lubricating phase and Ag₂CrO₄ as the high-temperature lubricating phase, and Ag being uniformly distributed within Ag₂CrO₄. From room temperature to 500°C, Ag diffuses to the coating surface to provide lubrication, and due to the protection of Ag₂CrO₄, Ag is not oxidized at higher temperatures. Furthermore, Ag₂CrO₄ softens above 500°C, making it easily sheared, thus ensuring good lubrication performance of the coating at high temperatures. Due to the synergistic lubricating effect of Ag and Ag₂CrO₄, the coating exhibits good lubricity and can be used over a wide temperature range. Furthermore, the dendritic microstructure of the Ag-Ag₂CrO₄ composite self-lubricating coating provides strong hydrophobicity, protecting it from corrosion in humid environments.

[0006] The purpose of employing a multilayer, multicomponent structure in this invention is that, in a multilayer, multicomponent system, the bonding layer should generally ensure good film-substrate bonding strength, the transition layer should possess excellent mechanical and tribological properties, and the functional layer should have a low coefficient of thermal expansion and low reactivity to reduce diffusion and wear. The characteristics of the constituent materials and structure of the multilayer, multicomponent structure film, as well as the highly complex interfacial effects between its layers, cause the multilayer high-temperature solid self-lubricating film to exhibit mechanical properties and corrosion resistance different from those of the single-layer materials that compose it. In the coating material, the bonding layer is a pure metallic Cr layer, and the transition layer is a CrN layer. The multilayer, multicomponent structure creates a gradual change in structure and composition to reduce the stress gradient of the coating, prevent coating peeling, and help improve the coating's temperature resistance and adhesion to the substrate.

[0007] Preferably, in the self-lubricating functional layer, the molar content of Cr atoms is 14% to 18%, and the molar content of Ag atoms is 13% to 26%.

[0008] Preferably, the thickness of the bonding layer is 0.2–0.3 μm, the thickness of the transition layer is 0.7–0.8 μm, and the thickness of the self-lubricating functional layer is 6–7 μm.

[0009] In a second aspect of the present invention, a method for preparing a dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material that is simple to produce, highly efficient, and easy to mass-produce is provided, comprising the following steps:

[0010] (1) Under an argon atmosphere, the substrate is subjected to plasma etching to remove the surface oxide layer, resulting in an etched substrate;

[0011] (2) Under an argon atmosphere, the Cr target is treated by arc discharge to deposit a bonding layer on the surface of the etched substrate;

[0012] (3) In an environment gas formed by argon and nitrogen, Cr target material is sputtered to deposit on the surface of the bonding layer to form a transition layer;

[0013] (4) In the ambient gas formed by argon and oxygen, AgCr target material is sputtered to deposit on the surface of the transition layer to form a self-lubricating functional layer, and the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material is prepared on the substrate surface.

[0014] Preferably, in step (1), the pressure of the argon atmosphere is 0.8 to 1.2 Pa.

[0015] Preferably, in step (1), during the plasma etching process, the ambient temperature is 140-180°C, the target current is 90-120A, the bias voltage is -200--100V, and the duty cycle is 40%-55%.

[0016] Preferably, in step (2), the pressure of the argon atmosphere is 0.8 to 1.2 Pa.

[0017] Preferably, in step (2), the ambient temperature during the arc discharge treatment is 140-180°C and the target current is 90-120A.

[0018] Preferably, in step (3), the pressure of the ambient gas is 0.8 to 1.2 Pa, and the volume percentage of nitrogen in the ambient gas is 50% to 85%.

[0019] Preferably, in step (3), during the sputtering process, the ambient temperature is 140-180°C and the target current is 90-120A.

[0020] Preferably, in step (4), the pressure of the ambient gas is 0.8 to 1.2 Pa, and the volume percentage of oxygen in the ambient gas is 15% to 50%.

[0021] Preferably, in step (4), during the sputtering process, the ambient temperature is 140-180°C and the target power is 500-800W.

[0022] In the above coating preparation process, when the plasma etching and cleaning is completed, the substrate surface is cleaned, the oxide scale is removed, and the adhesion between the coating and the substrate is improved. Cr is burned off from the Cr target using an arc discharge method. During this process, the substrate surface is bombarded with continuous high-energy ions, and defects are formed due to the high-energy ion bombardment, enhancing surface activity. The high energy of the arc discharge forms a bonding layer with good adhesion. After the bonding layer is prepared, argon and nitrogen are introduced, and the flow ratio of argon and nitrogen is controlled to ensure that the nitrogen content in the environment reaches the designed range. During sputtering, Cr atoms combine with N atoms and deposit to form a CrN transition layer. There is good adhesion between the pure Cr bonding layer and the CrN transition layer. After the CrN transition layer is prepared, argon and oxygen are introduced, and the flow ratio of argon and oxygen is controlled to prepare an Ag-Ag₂CrO₄ self-lubricating functional layer. During the deposition process, the presence of the active gas O₂ causes Ag to deposit simultaneously in the form of pure metallic Ag and Ag₂CrO₄. As the O2 ratio increases, Ag gradually transitions from being deposited as a pure metallic element to being deposited as pure Ag₂CrO₄. The higher the O2 ratio, the less pure metallic Ag is present in the deposited coating. The lower the O2 ratio, the more Ag fails to react with O2 during sputtering, resulting in a higher content of pure metallic Ag in the deposited coating, and vice versa.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] This invention provides a dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material. This coating exhibits good lubricity and can be used over a wide temperature range. The coating is hydrophobic, has good corrosion resistance, and good oxidation resistance. The coating has good adhesion to the substrate and excellent temperature resistance and wear resistance.

[0025] This invention provides a method for preparing a dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material, which has a simple and efficient production process and is easy to mass-produce. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the Nano100 arc-magnetic control nanocomposite coating machine used in this invention. In the figure, 1 is the air inlet, 2 is the heater, 3 is the AgCr target, 4 is the Cr target, 5 is the unused target placement position, 6 is the sample holder, 7 is the substrate, 8 is the rotating frame, 9 is the vacuum pump, 10 is the auxiliary anode, and 11 is the baffle.

[0027] Figure 2 This is a schematic diagram of the structure of a dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material attached to the surface of a substrate;

[0028] Figure 3 The microstructure of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material is shown in (a) and (b), which correspond to the characterization results of Example 1 and Example 2, respectively.

[0029] Figure 4 This is a schematic diagram illustrating the principle behind the hydrophobicity of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material.

[0030] Figure 5 The results are the water contact angle test results of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material, where (a) to (c) correspond to the test results of Examples 1 to 3 respectively;

[0031] Figure 6 These are the tribological property test results of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating materials in Examples 1-3;

[0032] Figure 7 These are X-ray diffraction (XRD) images of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating materials of Examples 1-3 after heat treatment and aging. Detailed Implementation

[0033] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0034] The substrate used in the following examples is 304 stainless steel.

[0035] The device used to prepare the composite self-lubricating coating material is the Nano100 arc-magnetic control nanocomposite coating machine, whose internal structure is as follows: Figure 1As shown. The main structure of the device is a vacuum chamber measuring 600mm × 600mm × 600mm. The vacuum chamber has three target placement positions; this invention uses AgCr target 3, Cr target 4, and target 5 is not used. Vacuum pump 9 can reduce the vacuum level of the vacuum chamber to the required value through the extraction port. Argon, nitrogen, and oxygen gases can be introduced through inlet 1, and different gases can be introduced as needed. Adjusting the gas flow rate changes the gas ratio in the vacuum chamber. Heater 2 can heat the vacuum chamber to the set temperature. Substrate 7 is fixed together with sample holder 6 on rotating frame 8, which can rotate freely. Anode rod 10 and baffle 11 provide plasma etching function to clean the substrate surface. During plasma etching, the Cr target participates in glow discharge to generate argon ions. Closing baffle 11 prevents Cr from depositing on the substrate during etching. This device uses a magnetron to form a ring magnetic field near the target, which restricts the movement of secondary electrons near the target. Under the combined influence of a toroidal magnetic field and an electric field, secondary electrons are trapped near the target and undergo circular motion. This electron trapping method increases the likelihood of particle collisions and significantly enhances the ionization degree of the sputtering gas. The increased ionization intensity also increases the plasma density near the target, resulting in a higher sputtering rate for magnetron sputtering. With the substrate completely immersed in the plasma, the prepared coating is uniform and dense, exhibits good coating wrapping properties, high repeatability, few coating defects, and precise thickness control.

[0036] Example 1

[0037] Preparation method of dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material:

[0038] (1) The vacuum chamber of the arc-magnetic control nanocomposite coating machine is evacuated, argon gas is introduced and the argon gas pressure is controlled to be 1Pa, the ambient temperature is set to 150℃, Cr target material is used, the target current is 100A, the bias voltage is -150V, the duty cycle is 50%, and the chemically cleaned substrate is subjected to plasma etching to remove its surface oxide layer and obtain the etched substrate.

[0039] (2) Keep the argon gas pressure at 1 Pa and the temperature at 150 °C. Set the target current to 100 A. The Cr target is treated by arc discharge to deposit a Cr bonding layer with a thickness of 0.3 μm on the surface of the etched substrate.

[0040] (3) Argon and nitrogen are introduced as ambient gases. The flow rate ratio of argon and nitrogen is 1:1. The ambient gas pressure is 1 Pa. The ambient temperature is set to 150℃. The target current is 100A. The Cr target is sputtered to combine Cr atoms with N atoms and deposit them on the surface of the Cr bonding layer to form a CrN transition layer with a thickness of 0.7 μm.

[0041] (4) After the CrN transition layer is prepared, nitrogen gas is stopped. Argon and oxygen are introduced as ambient gases. The flow rate ratio of argon to oxygen is 5:1, the ambient gas pressure is 1 Pa, the target power is set to 700 W, and the ambient temperature is 150 °C. The AgCr target material is sputtered to deposit an Ag-Ag2CrO4 self-lubricating functional layer with a dendritic microstructure formed by Ag and Ag2CrO4 composite on the surface of the CrN transition layer. The thickness of the self-lubricating functional layer is 6 μm. After preparation, it is naturally cooled to complete the preparation of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material.

[0042] The energy dispersive spectroscopy (EDS) analysis revealed that the self-lubricating functional layer of the coating in this embodiment contained 18% Cr and 13% Ag atoms.

[0043] Example 2

[0044] Preparation method of dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material:

[0045] (1) The vacuum chamber of the arc-magnetic control nanocomposite coating machine is evacuated, argon gas is introduced and the argon gas pressure is controlled to be 1Pa, the ambient temperature is set to 150℃, Cr target material is used, the target current is 100A, the bias voltage is -150V, the duty cycle is 50%, and the chemically cleaned substrate is subjected to plasma etching to remove its surface oxide layer and obtain the etched substrate.

[0046] (2) Keep the argon gas pressure at 1 Pa and the temperature at 150 °C. Set the target current to 100 A. The Cr target is treated by arc discharge to deposit a Cr bonding layer with a thickness of 0.3 μm on the surface of the etched substrate.

[0047] (3) Argon and nitrogen are introduced as ambient gases. The flow rate ratio of argon and nitrogen is 1:1. The ambient gas pressure is 1 Pa. The ambient temperature is set to 150℃. The target current is 100A. The Cr target is sputtered to combine Cr atoms with N atoms and deposit them on the surface of the Cr bonding layer to form a CrN transition layer with a thickness of 0.7 μm.

[0048] (4) After the CrN transition layer is prepared, nitrogen gas is stopped. Argon and oxygen are introduced as ambient gases. The flow rate ratio of argon to oxygen is 2:1, the ambient gas pressure is 1 Pa, the target power is set to 700 W, and the ambient temperature is 150 °C. The AgCr target material is sputtered to deposit an Ag-Ag2CrO4 self-lubricating functional layer with a dendritic microstructure formed by Ag and Ag2CrO4 composite on the surface of the CrN transition layer. The thickness of the self-lubricating functional layer is 6 μm. After preparation, it is naturally cooled to complete the preparation of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material.

[0049] The energy dispersive spectroscopy (EDS) analysis revealed that the self-lubricating functional layer of the coating in this embodiment contained 23% Cr and 15% Ag.

[0050] Example 3

[0051] Preparation method of dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material:

[0052] (1) The vacuum chamber of the arc-magnetic control nanocomposite coating machine is evacuated, argon gas is introduced and the argon gas pressure is controlled to be 1Pa, the ambient temperature is set to 150℃, Cr target material is used, the target current is 100A, the bias voltage is -150V, the duty cycle is 50%, and the chemically cleaned substrate is subjected to plasma etching to remove its surface oxide layer and obtain the etched substrate.

[0053] (2) Keep the argon gas pressure at 1 Pa and the temperature at 150 °C. Set the target current to 100 A. The Cr target is treated by arc discharge to deposit a Cr bonding layer with a thickness of 0.3 μm on the surface of the etched substrate.

[0054] (3) Argon and nitrogen are introduced as ambient gases. The flow rate ratio of argon and nitrogen is 1:1. The ambient gas pressure is 1 Pa. The ambient temperature is set to 150℃. The target current is 100A. The Cr target is sputtered to combine Cr atoms with N atoms and deposit them on the surface of the Cr bonding layer to form a CrN transition layer with a thickness of 0.7 μm.

[0055] (4) After the CrN transition layer is prepared, nitrogen gas is stopped. Argon and oxygen are introduced as ambient gases. The flow rate ratio of argon to oxygen is 1:1, the ambient gas pressure is 1 Pa, the target power is set to 700 W, and the ambient temperature is 150 °C. The AgCr target material is sputtered to deposit an Ag-Ag2CrO4 self-lubricating functional layer with a dendritic microstructure formed by Ag and Ag2CrO4 composite on the surface of the CrN transition layer. The thickness of the self-lubricating functional layer is 6 μm. After preparation, it is naturally cooled to complete the preparation of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material.

[0056] The energy dispersive spectroscopy (EDS) analysis revealed that the self-lubricating functional layer of the coating in this embodiment contained 14% Cr and 26% Ag.

[0057] Example 4

[0058] Preparation method of dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material:

[0059] (1) The vacuum chamber of the arc-magnetic control nanocomposite coating machine is evacuated, argon gas is introduced and the argon gas pressure is controlled at 0.8 Pa. The ambient temperature is set at 140℃. Cr target material is used, the target current is 120A, the bias voltage is -200V, the duty cycle is 40%, and plasma etching is performed on the chemically cleaned substrate to remove its surface oxide layer and obtain the etched substrate.

[0060] (2) Keep the argon gas pressure at 0.8 Pa and the temperature at 140 °C. Set the target current to 120 A. The Cr target is treated by arc discharge to deposit a Cr bonding layer with a thickness of 0.2 μm on the surface of the etched substrate.

[0061] (3) Argon and nitrogen are introduced as ambient gases. The flow rate ratio of argon to nitrogen is 3:17, the ambient gas pressure is 0.8 Pa, the ambient temperature is set to 140℃, and the target current is 120 A. The Cr target is sputtered to combine Cr atoms with N atoms and deposit them on the surface of the Cr bonding layer to form a CrN transition layer with a thickness of 0.7 μm.

[0062] (4) After the CrN transition layer is prepared, nitrogen gas is stopped. Argon and oxygen are introduced as ambient gases. The flow rate ratio of argon to oxygen is 17:3. The ambient gas pressure is 0.8 Pa. The target power is set to 800 W and the ambient temperature is 140 °C. The AgCr target material is sputtered to deposit an Ag-Ag2CrO4 self-lubricating functional layer with dendritic microstructure formed by Ag and Ag2CrO4 composite on the surface of the CrN transition layer. The thickness of the self-lubricating functional layer is 6 μm. After preparation, it is naturally cooled to complete the preparation of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material.

[0063] Example 5

[0064] Preparation method of dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material:

[0065] (1) The vacuum chamber of the arc-magnetic control nanocomposite coating machine is evacuated, argon gas is introduced and the argon gas pressure is controlled at 1.2 Pa. The ambient temperature is set at 180℃. Cr target material is used, the target current is 90A, the bias voltage is -100V, the duty cycle is 55%, and plasma etching is performed on the chemically cleaned substrate to remove its surface oxide layer and obtain the etched substrate.

[0066] (2) Keep the argon gas pressure at 1.2 Pa and the temperature at 180 °C. Set the target current to 90 A. The Cr target is treated by arc discharge to deposit a Cr bonding layer with a thickness of 0.3 μm on the surface of the etched substrate.

[0067] (3) Argon and nitrogen are introduced as ambient gases. The flow rate ratio of argon and nitrogen is 1:1. The ambient gas pressure is 1.2 Pa. The ambient temperature is set to 180℃. The target current is 90A. The Cr target is sputtered to combine Cr atoms with N atoms and deposit them on the surface of the Cr bonding layer to form a CrN transition layer with a thickness of 0.8 μm.

[0068] (4) After the CrN transition layer is prepared, nitrogen gas is stopped. Argon and oxygen are introduced as ambient gases. The flow rate ratio of argon to oxygen is 1:1, the ambient gas pressure is 1.2 Pa, the target power is set to 500 W, and the ambient temperature is 180 °C. The AgCr target material is sputtered to deposit an Ag-Ag2CrO4 self-lubricating functional layer with a dendritic microstructure formed by Ag and Ag2CrO4 composite on the surface of the CrN transition layer. The thickness of the self-lubricating functional layer is 7 μm. After preparation, it is naturally cooled to complete the preparation of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material.

[0069] Test Example 1

[0070] The comprehensive performance of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material of some embodiments of the present invention was tested.

[0071] The dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating materials obtained in Examples 1-3 were tested using a multifunctional scratch tester. The CPR of the above composite self-lubricating coatings was measured. S Values ​​range from 300 to 483 N 2 The range between these values ​​indicates that the coating material has a high bonding strength with the substrate. Figure 2 The diagram shows the coating structure designed for this invention. As can be seen from the diagram, the coating has a multi-layer and multi-component structure. Based on the test results, a good compositional and structural gradient and a good hardness gradient are formed between the pure Cr bonding layer, the CrN transition layer, and the Ag-Ag2CrO4 self-lubricating functional layer, which effectively reduces the stress of the coating and improves the bonding strength between the coating and the substrate.

[0072] The microstructure of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating materials of Examples 1 and 2 was observed by scanning electron microscopy, and the water contact angle of the composite self-lubricating coating materials of Examples 1 to 3 was measured by a contact angle meter. Figure 3 In the figures a and b, the microstructures of Examples 1 and 2 are respectively observed, and a dendritic hydrophobic structure can be observed. Figure 4 The hydrophobic principle of the dendritic hydrophobic structure of this invention lies in its surface morphology, characterized by unevenness and high roughness, which helps to reduce the contact area between water and the coating surface, thus exhibiting hydrophobicity. Correspondingly, from... Figure 5The water contact angle of the coating could be measured. During the test, the volume of the droplet was 3 μL. The water contact angle for Example 1 was 145°, for Example 2 it was 148°, and for Example 3 it was 116°. These tests demonstrate that the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating possesses strong hydrophobicity. This property reduces the contact area between the coating and water in humid environments, protecting the coating from corrosion. Therefore, this invention exhibits good corrosion resistance in humid environments.

[0073] The lubricity and wear resistance of the dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating materials of Examples 1-3 were tested using an MS-T300 ball-and-disc tribometer. The tests were conducted at room temperature, using 304 stainless steel balls with a diameter of 3 mm, a rotation speed of 200 rpm, a friction radius of 3 mm, and a test time of 5 minutes. Figure 6 It can be seen that the friction coefficient of Example 1 is stable at around 0.15, the friction coefficient of Example 2 is 0.15 to 0.5, and the friction coefficient of Example 3 is 0.15 to 0.2. The above test results show that the Ag-Ag2CrO4 composite self-lubricating coating material of the present invention has good lubricity and wear resistance.

[0074] The dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating materials of Examples 1-3 were subjected to X-ray diffraction analysis after being kept at 650°C for 2 hours in an air environment. Figure 7 As shown, the coatings prepared in Examples 1, 2, and 3 mainly consist of Ag and Ag₂CrO₄ after heat treatment, and the coatings did not peel off after heat treatment. This indicates that the Ag-Ag₂CrO₄ composite self-lubricating coating of the present invention has good temperature resistance, oxidation resistance, and good bonding strength at high temperatures.

[0075] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material, characterized in that: The dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material has a multi-layer and multi-component structure, consisting of a bonding layer, a transition layer, and a self-lubricating functional layer in sequence; the bonding layer is a Cr layer, the transition layer is a CrN layer, and the self-lubricating functional layer is an Ag-Ag2CrO4 layer with a dendritic microstructure prepared by combining Ag and Ag2CrO4.

2. The dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material according to claim 1, characterized in that: In the self-lubricating functional layer, the molar content of Cr atoms is 14% to 18%, and the molar content of Ag atoms is 13% to 26%.

3. The dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material according to claim 1, characterized in that: The thickness of the bonding layer is 0.2–0.3 μm, the thickness of the transition layer is 0.7–0.8 μm, and the thickness of the self-lubricating functional layer is 6–7 μm.

4. A method for preparing a dendritic hydrophobic Ag-Ag2CrO4 composite self-lubricating coating material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Under an argon atmosphere, the substrate is subjected to plasma etching to remove the surface oxide layer, resulting in an etched substrate; (2) Under an argon atmosphere, the Cr target is treated by arc discharge to deposit a bonding layer on the surface of the etched substrate; (3) In an environment gas formed by argon and nitrogen, Cr target material is sputtered to deposit on the surface of the bonding layer to form a transition layer; (4) In an environment gas formed by argon and oxygen, AgCr target material is sputtered to deposit a self-lubricating functional layer on the surface of the transition layer, thus completing the preparation.

5. The method according to claim 4, characterized in that: In step (1), the pressure of the argon atmosphere is 0.8 to 1.2 Pa; in the plasma etching process, the ambient temperature is 140 to 180 °C, the target current is 90 to 120 A, the bias voltage is -200 to -100 V, and the duty cycle is 40% to 55%.

6. The method according to claim 4, characterized in that: In step (2), the pressure of the argon atmosphere is 0.8 to 1.2 Pa; in the arc discharge treatment, the ambient temperature is 140 to 180°C and the target current is 90 to 120 A.

7. The method according to claim 4, characterized in that: In step (3), the pressure of the ambient gas is 0.8 to 1.2 Pa, and the volume percentage of nitrogen in the ambient gas is 50% to 85%.

8. The method according to claim 4, characterized in that: In step (3), during the sputtering process, the ambient temperature is 140-180℃ and the target current is 90-120A.

9. The method according to claim 4, characterized in that: In step (4), the pressure of the ambient gas is 0.8 to 1.2 Pa, and the volume percentage of oxygen in the ambient gas is 15% to 50%.

10. The method according to claim 4, characterized in that: In step (4), during the sputtering process, the ambient temperature is 140-180℃ and the target power is 500-800W.

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