A high-temperature self-lubricating coating material of Ag2CrO4 and its preparation method

Abstract

This invention discloses a high-temperature self-lubricating coating material of Ag₂CrO₄ and its preparation method, belonging to the field of sputtering coating technology. The coating material comprises a multilayer structure consisting of a bonding layer, a transition layer, and a self-lubricating functional layer. The bonding layer is a Cr layer, the transition layer includes a CrN layer and an Ag-CrN layer formed by the composite of Ag and CrN, and the self-lubricating functional layer is an Ag₂CrO₄ layer. The layer sequence is Cr layer, CrN layer, Ag-CrN layer, and Ag₂CrO₄ layer, wherein the Cr layer is the contact layer between the coating material and the substrate. This coating material exhibits good bonding strength with the substrate and is not easily detached; it has excellent temperature resistance, is not easily oxidized at high temperatures, and has good load-bearing capacity and wear resistance, providing stable lubrication at high temperatures. This invention also provides a preparation method for this coating material, which is simple to operate, highly efficient, and easy to scale up for mass production.

Description

Technical Field

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

[0002] High-temperature self-lubricating coatings have been widely studied in recent years because they can provide a high-quality lubricating film for the friction interface in high-temperature environments. High-temperature self-lubricating coatings are generally divided into three components: matrix phase, reinforcing phase, and lubricating phase. They work together to provide good tribological properties at high temperatures as well as excellent thermal and chemical stability. The matrix phase mainly bears the load and friction wear; the reinforcing phase is used to improve the thermal stability, oxidation resistance and other properties of the high-temperature self-lubricating coating; the lubricating phase provides good tribological properties at high temperatures. When the temperature rises, the lubricating phase in the matrix phase continuously diffuses to the friction interface and forms a continuous low-shear strength lubricating film at the friction interface, covering the entire friction interface. The lubricating film separates the friction interface, preventing direct contact and thus ensuring a low coefficient of friction at high temperatures. The lubricating phase is an important component of high-temperature solid self-lubricating coatings and is one of the keys to maintaining a low coefficient of friction at high temperatures. Generally speaking, the main materials used in the lubricating phase are as follows: (1) Materials with layered structures and weak bonding between layers, such as graphite and MoS2. (2) Soft metals with many slip surfaces, such as Ag and Au. (3) Metal fluorides and low-melting-point metal oxides. Commonly used lubricating phases have, or under certain conditions have, low shear strength.

[0003] Most commonly used lubricating phases are temperature-dependent during use. MoS2 exhibits excellent tribological properties between room temperature and 300°C. However, when the temperature exceeds 300°C and it is exposed to air, the lubricating effect of MoS2 rapidly decreases due to oxidation, and the resulting MoO3 leads to a high coefficient of friction and high wear rate. Graphite is an allotrope of carbon with a layered structure. The C atoms in the layers are strongly bound by covalent bonds, while the layers are bonded by relatively weak van der Waals forces. It has low shear strength in the direction parallel to the basal plane and is easily sheared. Graphite is currently mainly used as a lubricating phase at medium and low temperatures. At high temperatures, graphite oxidizes rapidly and loses its lubricating effect. WS2 has the same lubrication mechanism as graphite and is a widely used lubricating phase, but its maximum operating temperature is only 540°C. It will oxidize and fail at temperatures above 540°C. Soft metals have low hardness and good ductility, and are widely used as lubricating phases in high-temperature self-lubricating coatings. However, as the temperature rises, the softness of soft metals increases, their load-bearing capacity decreases, and they are squeezed out of the friction interface, resulting in a poorer lubrication effect. Ag can act as a lubricant in the range of room temperature to 500°C, but it loses its lubricating properties due to oxidation when the temperature is above 500°C or in a humid environment.

[0004] To increase the service temperature of high-temperature self-lubricating coatings, selecting a high-temperature resistant lubricating phase is one feasible solution. Using metal oxides as the lubricating phase has the potential to raise the service temperature of high-temperature self-lubricating coatings to 1000℃. Oxide lubrication is a complex issue, and currently, the most effective method is considered to be in-situ formation. Generally, under high-temperature conditions, in-situ formed low-melting-point metal oxides undergo a transformation from brittle to ductile, making them more susceptible to plastic deformation and thus providing a lubricating effect. Summary of the Invention

[0005] In view of the above-mentioned deficiencies of the prior art, in a first aspect of the present invention, an Ag2CrO4 high-temperature self-lubricating coating material with high oxidation resistance, high load-bearing capacity and high bonding strength at high temperatures is provided. The Ag2CrO4 high-temperature self-lubricating coating material includes a multilayer structure composed of a bonding layer, a transition layer and a self-lubricating functional layer; the bonding layer is a Cr layer, the transition layer includes a CrN layer and an Ag-CrN layer formed by the composite of Ag and CrN, and the self-lubricating functional layer is an Ag2CrO4 layer; the layer sequence is Cr layer, CrN layer, Ag-CrN layer and Ag2CrO4 layer, wherein the Cr layer is the contact layer between the Ag2CrO4 high-temperature self-lubricating coating material and the substrate to which it is attached.

[0006] Preferably, the thickness of the Cr layer is 0.2–0.3 μm, the thickness of the CrN layer is 0.7–0.8 μm, and the thickness of the Ag-CrN layer is 1.6–2.0 μm.

[0007] Preferably, in the Ag-CrN layer, the molar content of Cr atoms is 15% to 18%, and the molar content of Ag atoms is 25% to 28%.

[0008] Preferably, in the Ag2CrO4 layer, the molar content of Cr atoms is 11% to 15%, and the molar content of Ag atoms is 32% to 35%.

[0009] In a second aspect of the present invention, a method for preparing a high-temperature self-lubricating coating material of Ag2CrO4 that is simple to operate, highly efficient, and easy to scale up is provided, comprising the following steps:

[0010] (1) The substrate is subjected to plasma etching in an argon atmosphere to remove the surface oxide layer and obtain an etched substrate;

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

[0012] (3) In a mixed gas atmosphere of argon and nitrogen, Cr target material is sputtered to deposit a CrN layer on the surface of the Cr layer;

[0013] (4) In a mixed gas atmosphere of argon and nitrogen, AgCr target material is sputtered to deposit an Ag-CrN layer on the surface of the CrN layer to obtain a composite coating.

[0014] (5) The composite coating is transferred to the air environment and heat-treated at a certain temperature to oxidize and form an Ag2CrO4 layer, thus completing the preparation.

[0015] Based on the structure, composition properties, and preparation process of the Ag2CrO4 high-temperature self-lubricating coating material of this invention, the design concept of this invention is to use the Ag2CrO4 oxide layer generated at the heat treatment temperature as the self-lubricating functional layer, and to use this metal oxide as the lubricating phase, which has the potential to increase the service temperature of the high-temperature self-lubricating coating to even higher temperatures. Generally, under high temperature conditions, the low-melting-point metal oxide generated in situ will transform from brittle to ductile, making it easy to undergo plastic deformation and thus play a lubricating role. The Ag2CrO4 high-temperature self-lubricating coating uses the Ag2CrO4 oxide generated at a relatively high temperature as a lubricant, which has good temperature resistance and is not easily oxidized at high temperatures. Multilayer and multi-component structures are an important development direction for high-temperature self-lubricating coatings. This invention uses a Cr layer, a CrN layer, an Ag-CrN layer, and an Ag2CrO4 layer to form a multilayer and multi-component system. In this system, the bonding layer should ensure good film-substrate bonding strength, the transition layer should have excellent mechanical and tribological properties, and the functional layer should have a low coefficient of thermal expansion and reactivity to reduce diffusion and wear. The characteristics of the constituent materials and structure of multilayer, multi-component thin films, as well as the highly complex interfacial effects between their layers, enable multilayer high-temperature solid self-lubricating thin films to exhibit mechanical properties and corrosion resistance that differ from those of the single-layer materials that compose them. In this invention, the bonding layer is a pure metallic Cr layer, and the transition layer is a composite layer of CrN and Ag-CrN, which helps to improve the coating's temperature resistance and adhesion to the substrate.

[0016] In the preparation process of Ag2CrO4 high-temperature self-lubricating coating material, after plasma etching, impurities such as the oxide layer on the substrate surface are removed, resulting in further surface cleaning and enhanced surface activity. This leads to higher bonding strength between the subsequently deposited coating and the substrate. Cr is burned off from a Cr target using an arc discharge method, utilizing the high energy of the arc discharge to form a bonding layer with good adhesion. After the pure Cr layer is prepared, a CrN transition layer is prepared under argon and nitrogen atmospheres. After the CrN transition layer is prepared, the substrate is rotated to an AgCr target, and the Ag-CrN composite layer is prepared further under argon and nitrogen atmospheres. The prepared Cr layer, CrN layer, and Ag-CrN composite layer all exhibit good adhesion. Finally, in an air environment, a heat treatment process is performed to prepare the Ag2CrO4 self-lubricating functional layer, resulting in the Ag2CrO4 high-temperature self-lubricating coating. A good compositional and structural gradient is formed between the Cr layer, CrN layer, Ag-CrN composite layer and Ag2CrO4 layer. Therefore, the Ag2CrO4 high-temperature self-lubricating coating has good bonding strength with the substrate, as well as good load-bearing capacity, lubricity and wear resistance.

[0017] Preferably, in step (1), the pressure of the argon gas is 0.8 to 1.2 Pa, and the ambient temperature of the plasma etching is 140 to 180 °C.

[0018] Preferably, in step (1), the plasma etching uses a Cr target, the target current is 90 to 120 A, the bias voltage is -200 to -100 V, and the duty cycle is 40% to 55%.

[0019] Preferably, in step (2), the pressure of the argon gas is 0.8 to 1.2 Pa, and the ambient temperature of the arc discharge treatment is 140 to 180°C.

[0020] Preferably, in step (2), the target current of the arc discharge treatment is 90-120A.

[0021] Preferably, in step (3), the pressure of the mixed gas is 0.8 to 1.2 Pa, the volume percentage of nitrogen in the mixed gas is 50% to 85%, and the ambient temperature of the sputtering is 140 to 180°C.

[0022] Preferably, in step (3), the sputtering target current is 90-120A.

[0023] Preferably, in step (4), the pressure of the mixed gas is 0.8 to 1.2 Pa, the volume percentage of nitrogen in the mixed gas is 40% to 85%, and the ambient temperature of the sputtering is 140 to 180°C.

[0024] Preferably, in step (4), the target power of the sputtering is 500-800W.

[0025] Preferably, in step (5), the temperature of the heat treatment is 600-800℃ and the treatment time is 1-3h.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] This invention provides a high-temperature self-lubricating coating material of Ag2CrO4. The coating material has good bonding strength with the substrate and is not easy to fall off. It has excellent temperature resistance, is not easy to oxidize at high temperatures, and has good load-bearing capacity and wear resistance, and can play a stable lubricating role at high temperatures.

[0028] This invention provides a method for preparing Ag2CrO4 high-temperature self-lubricating coating material, which has a simple and efficient production process and is easy to scale up. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the Nano100 arc-magnetic control nanocomposite coating machine used in the embodiment. 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 material 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.

[0030] Figure 2 A schematic diagram of the structure of Ag2CrO4 high-temperature self-lubricating coating material adhering to the surface of a substrate;

[0031] Figure 3 The results are the high-temperature oxidation resistance test results of the Ag2CrO4 high-temperature self-lubricating coating materials in Examples 1-4;

[0032] Figure 4 The results are tribological property test results, with (a) to (d) corresponding to the results of Ag2CrO4 high-temperature self-lubricating coating materials in Examples 1 to 4, respectively.

[0033] Figure 5 The results are the hardness test results of the Ag2CrO4 high-temperature self-lubricating coating materials in Examples 1-4. Detailed Implementation

[0034] 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.

[0035] The substrate used in the following examples is 304 stainless steel.

[0036] In this embodiment, the Ag2CrO4 high-temperature self-lubricating coating material was prepared using a Nano100 arc-magnetic-controlled nanocomposite coating machine, and its internal structure is as follows: Figure 1 As shown, the device mainly consists of a power system, heating system, vacuum system, gas path system, and electrical control system. The main structure is a vacuum chamber measuring 600mm × 600mm × 600mm. The vacuum chamber has three target placement positions. This invention uses AgCr target 3 for the preparation of the Ag-CrN composite layer; Cr target 4 for the preparation of the Cr bonding layer and CrN transition layer; 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. Gas can be introduced into the vacuum chamber through inlet 1; 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 on sample holder 6, which can rotate freely with rotating frame 8. Anode rod 10 and baffle 11 provide plasma etching function to clean the substrate surface. 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 the toroidal magnetic field and electric field, secondary electrons are trapped near the target and undergo circular motion. This electron trapping method increases the likelihood of particle collisions, significantly enhancing the ionization level of the sputtered gas. The increased ionization intensity also increases the plasma density near the target, resulting in a higher sputtering rate for magnetron sputtering.

[0037] Example 1

[0038] Preparation method of Ag2CrO4 high-temperature self-lubricating coating material:

[0039] (1) After evacuating the vacuum chamber of the Nano100 arc-magnetic control nanocomposite coating machine, argon gas is introduced. The argon gas pressure is 1 Pa. At 150 °C, Cr target material is used. The target current is set to 100 A, the bias voltage is -150 V, and the duty cycle is 50%. Plasma etching is performed on the substrate to remove its surface oxide layer and obtain the etched substrate.

[0040] (2) Maintain the argon gas pressure at 1 Pa and use the Cr target to perform arc discharge treatment. This step is carried out at 150 °C and the target current is 100 A. The Cr is burned off from the Cr target and deposited on the surface of the etched substrate to form a Cr layer with a thickness of 0.3 μm.

[0041] (3) Argon and nitrogen are introduced, with a flow rate ratio of 1:1 and a gas pressure of 1 Pa. In this mixed gas atmosphere, Cr target is used for sputtering at 150°C and a target current of 100A. Cr atoms combine with N atoms and are deposited on the surface of the Cr layer to form a CrN layer with a thickness of 0.7 μm.

[0042] (4) Continue to introduce argon and nitrogen gas, with a flow rate ratio of argon to nitrogen of 1:1 and a gas pressure of 1 Pa. Adjust the target power to 700 W and sputter using AgCr target material at 150 °C. Ag atoms, Cr atoms and N atoms combine and are deposited on the surface of the CrN layer respectively, forming a 2 μm Ag-CrN layer to obtain a composite coating.

[0043] (5) The composite coating is transferred to the air environment and kept at 760°C for 2 hours to prepare the Ag2CrO4 layer. Then it is naturally cooled to room temperature to complete the preparation of the Ag2CrO4 high temperature self-lubricating coating material.

[0044] The elemental composition of the Ag-CrN layer and the Ag2CrO4 layer was tested using an energy dispersive spectroscopy (EDS) instrument. The results showed that in the Ag-CrN layer of this embodiment, the molar content of Cr atoms was 16% and the molar content of Ag atoms was 28%; in the Ag2CrO4 layer, the molar content of Cr atoms was 11% and the molar content of Ag atoms was 32%.

[0045] Example 2

[0046] Preparation method of Ag2CrO4 high-temperature self-lubricating coating material:

[0047] (1) After evacuating the vacuum chamber of the Nano100 arc-magnetic control nanocomposite coating machine, argon gas is introduced. The argon gas pressure is 1 Pa. At 150 °C, Cr target material is used. The target current is set to 100 A, the bias voltage is -150 V, and the duty cycle is 50%. Plasma etching is performed on the substrate to remove its surface oxide layer and obtain the etched substrate.

[0048] (2) Maintain the argon gas pressure at 1 Pa and use the Cr target to perform arc discharge treatment. This step is carried out at 150 °C and the target current is 100 A. The Cr is burned off from the Cr target and deposited on the surface of the etched substrate to form a Cr layer with a thickness of 0.3 μm.

[0049] (3) Argon and nitrogen are introduced, with a flow rate ratio of 1:1 and a gas pressure of 1 Pa. In this mixed gas atmosphere, Cr target is used for sputtering at 150°C and a target current of 100A. Cr atoms combine with N atoms and are deposited on the surface of the Cr layer to form a CrN layer with a thickness of 0.7 μm.

[0050] (4) Continue to introduce argon and nitrogen gas, with a flow rate ratio of argon to nitrogen of 1:2, a gas pressure of 1 Pa, and adjust the target power to 700 W. Sputtering is performed using an AgCr target at 150 °C. Ag atoms, Cr atoms and N atoms combine and are deposited on the surface of the CrN layer respectively, forming a 1.7 μm Ag-CrN layer, thus obtaining a composite coating.

[0051] (5) The composite coating is transferred to the air environment and kept at 760°C for 2 hours to prepare the Ag2CrO4 layer. Then it is naturally cooled to room temperature to complete the preparation of the Ag2CrO4 high temperature self-lubricating coating material.

[0052] The elemental composition of the Ag-CrN layer and the Ag2CrO4 layer was tested using an energy dispersive spectroscopy (EDS) instrument. The results showed that in the Ag-CrN layer of this embodiment, the molar content of Cr atoms was 18% and the molar content of Ag atoms was 25%; in the Ag2CrO4 layer, the molar content of Cr atoms was 11% and the molar content of Ag atoms was 32%.

[0053] Example 3

[0054] Preparation method of Ag2CrO4 high-temperature self-lubricating coating material:

[0055] (1) After evacuating the vacuum chamber of the Nano100 arc-magnetic control nanocomposite coating machine, argon gas is introduced. The argon gas pressure is 1 Pa. At 150 °C, Cr target material is used. The target current is set to 100 A, the bias voltage is -150 V, and the duty cycle is 50%. Plasma etching is performed on the substrate to remove its surface oxide layer and obtain the etched substrate.

[0056] (2) Maintain the argon gas pressure at 1 Pa and use the Cr target to perform arc discharge treatment. This step is carried out at 150 °C and the target current is 100 A. The Cr is burned off from the Cr target and deposited on the surface of the etched substrate to form a Cr layer with a thickness of 0.2 μm.

[0057] (3) Argon and nitrogen are introduced, with a flow rate ratio of 1:1 and a gas pressure of 1 Pa. In this mixed gas atmosphere, Cr target is used for sputtering at 150°C and a target current of 100A. Cr atoms combine with N atoms and are deposited on the surface of the Cr layer to form a CrN layer with a thickness of 0.7 μm.

[0058] (4) Continue to introduce argon and nitrogen gas, with a flow rate ratio of argon to nitrogen of 1:5 and a gas pressure of 1 Pa. Adjust the target power to 700 W and sputter using an AgCr target at 150 °C. Ag atoms, Cr atoms and N atoms combine and are deposited on the surface of the CrN layer respectively, forming a 1.6 μm Ag-CrN layer to obtain a composite coating.

[0059] (5) The composite coating is transferred to the air environment and kept at 648°C for 2 hours to prepare the Ag2CrO4 layer. Then it is naturally cooled to room temperature to complete the preparation of the Ag2CrO4 high temperature self-lubricating coating material.

[0060] The elemental composition of the Ag-CrN layer and the Ag2CrO4 layer was tested using an energy dispersive spectroscopy (EDS) instrument. The results showed that in the Ag-CrN layer of this embodiment, the molar content of Cr atoms was 15% and the molar content of Ag atoms was 25%; in the Ag2CrO4 layer, the molar content of Cr atoms was 15% and the molar content of Ag atoms was 35%.

[0061] Example 4

[0062] Preparation method of Ag2CrO4 high-temperature self-lubricating coating material:

[0063] (1) After evacuating the vacuum chamber of the Nano100 arc-magnetic control nanocomposite coating machine, argon gas is introduced. The argon gas pressure is 1 Pa. At 150 °C, Cr target material is used. The target current is set to 100 A, the bias voltage is -150 V, and the duty cycle is 50%. Plasma etching is performed on the substrate to remove its surface oxide layer and obtain the etched substrate.

[0064] (2) Maintain the argon gas pressure at 1 Pa and use the Cr target to perform arc discharge treatment. This step is carried out at 150 °C and the target current is 100 A. The Cr is burned off from the Cr target and deposited on the surface of the etched substrate to form a Cr layer with a thickness of 0.2 μm.

[0065] (3) Argon and nitrogen are introduced, with a flow rate ratio of 1:1 and a gas pressure of 1 Pa. In this mixed gas atmosphere, Cr target is used for sputtering at 150°C and a target current of 100A. Cr atoms combine with N atoms and are deposited on the surface of the Cr layer to form a CrN layer with a thickness of 0.7 μm.

[0066] (4) Continue to introduce argon and nitrogen gas, with a flow rate ratio of argon to nitrogen of 1:5 and a gas pressure of 1 Pa. Adjust the target power to 700 W and sputter using an AgCr target at 150 °C. Ag atoms, Cr atoms and N atoms combine and are deposited on the surface of the CrN layer respectively, forming a 1.6 μm Ag-CrN layer to obtain a composite coating.

[0067] (5) The composite coating is transferred to the air environment and kept at 760°C for 2 hours to prepare the Ag2CrO4 layer. Then it is naturally cooled to room temperature to complete the preparation of the Ag2CrO4 high temperature self-lubricating coating material.

[0068] The elemental composition of the Ag-CrN layer and the Ag2CrO4 layer was tested using an energy dispersive spectroscopy (EDS) instrument. The results showed that in the Ag-CrN layer of this embodiment, the molar content of Cr atoms was 15% and the molar content of Ag atoms was 25%; in the Ag2CrO4 layer, the molar content of Cr atoms was 11% and the molar content of Ag atoms was 32%.

[0069] Example 5

[0070] Preparation method of Ag2CrO4 high-temperature self-lubricating coating material:

[0071] (1) After evacuating the vacuum chamber of the Nano100 arc-magnetic control nanocomposite coating machine, argon gas is introduced. The argon gas pressure is 0.8 Pa. At 140 °C, Cr target material is used. The target current is set to 120 A, the bias voltage is -200 V, and the duty cycle is 40%. Plasma etching is performed on the substrate to remove its surface oxide layer and obtain the etched substrate.

[0072] (2) Keep the argon gas pressure at 0.8 Pa and use the Cr target to perform arc discharge treatment. This step is carried out at 140 °C and the target current is 120 A. The Cr is burned off from the Cr target and deposited on the surface of the etched substrate to form a Cr layer with a thickness of 0.3 μm.

[0073] (3) Argon and nitrogen are introduced, with a flow rate ratio of 3:17 and a gas pressure of 0.8 Pa. In this mixed gas atmosphere, Cr target is used for sputtering at 140°C and a target current of 120 A. Cr atoms combine with N atoms and are deposited on the surface of the Cr layer to form a CrN layer with a thickness of 0.8 μm.

[0074] (4) Continue to introduce argon and nitrogen gas, with a flow rate ratio of argon to nitrogen of 3:17, a gas pressure of 0.8 Pa, and adjust the target power to 800 W. Sputtering is performed using an AgCr target at 140 °C. Ag atoms, Cr atoms and N atoms combine and are deposited on the surface of the CrN layer respectively, forming a 2 μm Ag-CrN layer to obtain a composite coating.

[0075] (5) The composite coating is transferred to the air environment and kept at 600℃ for 2 hours to prepare the Ag2CrO4 layer. Then it is naturally cooled to room temperature to complete the preparation of the Ag2CrO4 high temperature self-lubricating coating material.

[0076] Example 6

[0077] Preparation method of Ag2CrO4 high-temperature self-lubricating coating material:

[0078] (1) After evacuating the vacuum chamber of the Nano100 arc-magnetic control nanocomposite coating machine, argon gas is introduced. The argon gas pressure is 1.2 Pa. At 180 °C, Cr target material is used. The target current is set to 90 A, the bias voltage is -100 V, and the duty cycle is 55%. Plasma etching is performed on the substrate to remove its surface oxide layer and obtain the etched substrate.

[0079] (2) Maintain the argon gas pressure at 1.2 Pa and use the Cr target to perform arc discharge treatment. This step is carried out at 180 °C and the target current is 90 A. The Cr is burned off from the Cr target and deposited on the surface of the etched substrate to form a Cr layer with a thickness of 0.3 μm.

[0080] (3) Argon and nitrogen are introduced, with a flow rate ratio of 1:1 and a gas pressure of 1.2 Pa. In this mixed gas atmosphere, Cr target is used for sputtering at 180°C and a target current of 90 A. Cr atoms combine with N atoms and are deposited on the surface of the Cr layer to form a CrN layer with a thickness of 0.8 μm.

[0081] (4) Continue to introduce argon and nitrogen gas, with a flow rate ratio of argon to nitrogen gas of 3:2, a gas pressure of 1.2 Pa, and adjust the target power to 500 W. Sputtering is performed using an AgCr target at 180 °C. Ag atoms, Cr atoms and N atoms combine and are deposited on the surface of the CrN layer respectively, forming a 2 μm Ag-CrN layer to obtain a composite coating.

[0082] (5) The composite coating is transferred to the air environment and kept at 800℃ for 2 hours to prepare the Ag2CrO4 layer. Then it is naturally cooled to room temperature to complete the preparation of the Ag2CrO4 high temperature self-lubricating coating material.

[0083] Test Example 1

[0084] The comprehensive performance of the Ag2CrO4 high-temperature self-lubricating coating material prepared in some embodiments of the present invention was tested.

[0085] Examples 1-4 were tested using a multi-functional scratch tester to measure the CPR of the corresponding Ag2CrO4 high-temperature self-lubricating coating materials. S Values ​​range from 450 to 800 N 2 This indicates that the coating material has a high bonding strength with the substrate. Figure 2 The structural diagram shows that the Cr layer, CrN layer, Ag-CrN layer, and Ag2CrO4 layer form a good compositional and structural gradient and a good hardness gradient, which effectively reduces the stress of the coating and thus improves the bonding strength between the coating and the substrate.

[0086] The high-temperature antioxidant properties of Examples 1-4 were tested. In an air environment, the coating samples of each example were heat-treated at room temperature, 500℃, 650℃, and 800℃ for 2 hours each. The molar content of oxygen atoms in the heat-treated high-temperature self-lubricating coatings was analyzed using energy dispersive spectroscopy. Figure 3The test results show that the oxygen atom molar content is stable at 41% to 44%, the oxygen atom molar content of the coating does not change significantly before and after heat treatment, and there is no peeling of the coating. This indicates that the Ag2CrO4 high-temperature self-lubricating coating prepared by this invention has good high-temperature oxidation resistance and good bonding strength with the substrate at high temperature.

[0087] The tribological properties of Examples 1-4 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. The rotational speed was set to 200 rpm, the friction radius to be 3 mm, and the test duration to be 5 minutes. Figure 4 As shown, the friction coefficient of Example 1 is stable at 0.16–0.25, the friction coefficients of Examples 2 and 4 are stable at 0.14–0.20, and the friction coefficient of Example 3 is stable at 0.30–0.40. These results indicate that the Ag2CrO4 high-temperature self-lubricating coating has a low friction coefficient, and the change with friction time is not significant, indicating good lubricity and wear resistance.

[0088] The hardness of the coatings in Examples 1-4 was tested using a microhardness tester at room temperature. Figure 5 It can be seen that the hardness values ​​of the Ag2CrO4 high-temperature self-lubricating coatings prepared in Examples 1 to 4 are stable at 450 to 520 HV, indicating that the high-temperature self-lubricating coatings have excellent load-bearing capacity.

[0089] 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. An Ag2Cr04 high temperature self-lubricating coating material, characterized by: The Ag2CrO4 high-temperature self-lubricating coating material comprises a multi-layer structure composed of a bonding layer, a transition layer and a self-lubricating functional layer; the bonding layer is a Cr layer, the transition layer comprises a CrN layer and an Ag-CrN layer formed by Ag and CrN, and the self-lubricating functional layer is an Ag2CrO4 layer; the order of the layers is Cr layer, CrN layer, Ag-CrN layer and Ag2CrO4 layer in sequence, wherein the Cr layer is a contact layer of the Ag2CrO4 high-temperature self-lubricating coating material and the attached base material.

2. The Ag2Cr04 high-temperature self-lubricating coating material according to claim 1, characterized in that: The thickness of the Cr layer is 0.2-0.3 μm, the thickness of the CrN layer is 0.7-0.8 μm, and the thickness of the Ag-CrN layer is 1.6-2.0 μm.

3. The Ag2Cr04 high-temperature self-lubricating coating material according to claim 1, characterized in that: In the Ag-CrN layer, the molar content of Cr atoms is 15%-18%, and the molar content of Ag atoms is 25%-28%.

4. The Ag2Cr04 high-temperature self-lubricating coating material according to claim 1, characterized in that: In the Ag2CrO4 layer, the molar content of Cr atoms is 11%-15%, and the molar content of Ag atoms is 32%-35%.

5. A method for producing the Ag2Cr04 high-temperature self-lubricating coating material according to any one of claims 1 to 4, characterized by, The method comprises the following steps: (1) performing plasma etching on the base material under an argon atmosphere to remove the surface oxide layer and obtain an etched base material; (2) depositing a Cr layer on the surface of the etched base material by arc discharge treatment of a Cr target under an argon atmosphere; (3) depositing a CrN layer on the surface of the Cr layer by sputtering of a Cr target under a mixed gas atmosphere of argon and nitrogen; (4) depositing an Ag-CrN layer on the surface of the CrN layer by sputtering of an AgCr target under a mixed gas atmosphere of argon and nitrogen to obtain a composite coating; (5) transferring the composite coating to an air environment and performing heat treatment at a certain temperature to oxidize and form an Ag2CrO4 layer, thereby completing the preparation.

6. The method of claim 5, wherein: In the step (1), the argon gas pressure is 0.8-1.2 Pa, the environmental temperature for plasma etching is 140-180 ℃, the target current for plasma etching is 90-120 A, the bias voltage is -200 to -100 V, and the duty cycle is 40%-55%.

7. The method of claim 5, wherein: In the step (2), the argon gas pressure is 0.8-1.2 Pa, the environmental temperature for arc discharge treatment is 140-180 ℃, and the target current for arc discharge treatment is 90-120 A.

8. The method of claim 5, wherein: In the step (3), the gas pressure of the mixed gas is 0.8-1.2 Pa, the volume percentage of nitrogen in the mixed gas is 50%-85%, the environmental temperature for sputtering is 140-180 ℃, and the target current for sputtering is 90-120 A.

9. The method of claim 5, wherein: In the step (4), the gas pressure of the mixed gas is 0.8-1.2 Pa, the volume percentage of nitrogen in the mixed gas is 40%-85%, the environmental temperature for sputtering is 140-180 ℃, and the target power for sputtering is 500-800 W.

10. The method of claim 5, wherein: In the step (5), the temperature for heat treatment is 600-800 ℃, and the treatment time is 1-3 h.

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