Gradient multi-layer Cu-Ag composite lubricating film as well as preparation method and application thereof
Through the gradient multi-layer Cu-Ag composite lubricating film structure, the problem of lubricating material failure in ultra-low temperature environment is solved, and excellent lubrication performance and wear resistance in ultra-low temperature environment are achieved. It is suitable for moving contact parts of equipment such as rocket engines, superconducting coils, and compressors.
Patent Information
- Application Number
- CN202510908289.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-02
- Publication Date
- 2025-09-26
AI Technical Summary
Existing lubricating materials are prone to failure in ultra-low temperature environments (<100K), and the friction coefficient increases, making it difficult to maintain good lubrication and wear resistance in ultra-low temperature environments.
A gradient multilayer Cu-Ag composite lubricating film structure is adopted, which includes a Ni bonding layer, a Ni-Cu bearing layer, a Cu-Ag gradient layer and an Ag functional lubricating layer from bottom to top. It is prepared by a closed magnetic field-multi-target co-sputtering deposition method, and the gradient change of the metal composition is controlled to improve the bonding strength and mechanical properties.
In ultra-low temperature environments, the gradient multilayer Cu-Ag composite lubricating film exhibits excellent self-lubricating properties, wear resistance and high bonding strength, and is suitable for moving contact parts in ultra-low temperature service environments.
Smart Images
Figure CN120700443A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of nanocomposite films and solid lubrication, and in particular to a gradient multilayer Cu-Ag composite lubricating film and a preparation method and application thereof. Background Art
[0002] With the development of aerospace and high-tech, an increasing number of moving parts are facing ultra-low temperature (<100K) service environments. For example, gears and bearings in liquid hydrogen and liquid oxygen engine pumps must operate at ultra-low temperatures of 50K; spacecraft face ultra-low temperatures of 100K in space; and the lunar surface can reach temperatures as low as 90K. Furthermore, refrigerators and superconducting devices also operate at ultra-low temperatures. Reliable, long-life lubrication of the moving mechanisms of these devices at ultra-low temperatures is a key technology limiting their development.
[0003] Currently, moving mechanisms are typically lubricated with grease or solid lubricant films. However, grease solidifies at temperatures below 200K, resulting in lubrication failure. Commonly used solid lubricant films such as MoS2 and diamond-like carbon-based films experience at least a doubling of their friction coefficient at low temperatures (below 120K). In ultra-low temperature environments, the microstructure, mechanical properties, and interactions of solid lubricants with the environment undergo significant changes. There is an urgent need for a self-lubricating material with excellent lubrication properties that can adapt to ultra-low temperature (<100K) service environments. Summary of the Invention
[0004] In view of this, the present invention provides a gradient multilayer Cu-Ag composite lubricating film and its preparation method and application. The gradient multilayer Cu-Ag composite lubricating film provided by the present invention has excellent self-lubrication and wear resistance in ultra-low temperature (<100K) environment.
[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0006] A gradient multilayer Cu-Ag composite lubricating film comprises, from bottom to top, a Ni bonding layer, a Ni-Cu bearing layer, a Cu-Ag gradient layer, and an Ag functional lubricating layer; the Ni-Cu bearing layer comprises Ni and Cu, and the Cu content gradually increases from bottom to top; the Cu-Ag gradient layer comprises Cu and Ag, and the Ag content gradually increases from bottom to top.
[0007] Preferably, the thickness of the Ni-Cu bearing layer is 300-800 nm; the thickness of the Cu-Ag gradient layer is 400-1000 nm.
[0008] Preferably, the thickness of the Ni bonding layer is 200-400 nm; the thickness of the Ag functional lubricating layer is 400-1000 nm.
[0009] The present invention also provides a method for preparing the gradient multilayer Cu-Ag composite lubricating film described in the above scheme, comprising the following steps:
[0010] Using a Ni target, a first sputtering is performed on the substrate surface to obtain a Ni bonding layer;
[0011] Using a Ni target and a Cu target, a second sputtering is performed on the surface of the Ni bonding layer to obtain a Ni-Cu supporting layer; during the second sputtering, the sputtering current of the Cu target is gradually increased;
[0012] Using a Cu target and an Ag target, a third sputtering is performed on the surface of the Ni-Cu bearing layer to obtain a Cu-Ag gradient layer; during the third sputtering, the sputtering current of the Ag target gradually increases;
[0013] A fourth sputtering process is performed on the surface of the Cu-Ag gradient layer using an Ag target to obtain an Ag functional lubricating layer.
[0014] Preferably, before the first sputtering, the substrate is further cleaned and plasma cleaned; the cleaning comprises: ultrasonically cleaning the substrate in petroleum ether and acetone in sequence;
[0015] The plasma cleaning conditions include: vacuum degree ≤ 2×10 -3 Pa, substrate rotation speed is 2 to 4 rpm, cleaning gas is argon, deposition gas pressure is 1 to 2 Pa, substrate negative bias voltage is 600 to 800 V, and cleaning time is 30 to 40 min.
[0016] Preferably, the first sputtering conditions include: the sputtering gas is argon, the deposition gas pressure is 0.1-0.3 Pa, the sputtering current of the Ni target is 1-3 A, and the substrate negative bias voltage is 100-200 V.
[0017] Preferably, the conditions for the second sputtering include: the sputtering gas is argon, the deposition gas pressure is 0.1~0.3Pa, the sputtering current of the Ni target is 1~3A, the sputtering current of the Cu target gradually increases from 0A to the maximum sputtering current, the maximum sputtering current of the Cu target is 1~3A, and the substrate negative bias is 100~200V.
[0018] Preferably, the conditions for the third sputtering include: the sputtering gas is argon, the deposition gas pressure is 0.1~0.3Pa, the sputtering current of the Cu target is 1~3A, the sputtering current of the Ag target gradually increases from 0A to the maximum sputtering current, the maximum sputtering current of the Ag target is 2~4A, and the substrate negative bias is 100~200V.
[0019] Preferably, the conditions for the fourth sputtering include: the sputtering gas is argon, the deposition gas pressure is 0.1-0.3 Pa, the sputtering current of the Ag target is 2-4 A, and the substrate negative bias voltage is 100-200 V.
[0020] The present invention also provides the use of the gradient multilayer Cu-Ag composite lubricating film described in the above scheme or the gradient multilayer Cu-Ag composite lubricating film prepared by the preparation method described in the above scheme in an ultra-low temperature environment, wherein the temperature of the ultra-low temperature environment is <100K.
[0021] The present invention provides a gradient multilayer Cu-Ag composite lubricating film, which comprises, from bottom to top, a Ni bonding layer, a Ni-Cu bearing layer, a Cu-Ag gradient layer, and an Ag functional lubricating layer. The Ni-Cu bearing layer comprises Ni and Cu, and the Cu content gradually increases from bottom to top. The Cu-Ag gradient layer comprises Cu and Ag, and the Ag content gradually increases from bottom to top. The gradient multilayer Cu-Ag composite lubricating film provided by the present invention is composed of metal elements such as Ni, Cu, and Ag. The elemental composition of the film changes in a gradient, and has good film-base bonding and low internal stress, and can maintain good mechanical properties even at low temperatures. In addition, the solid solution formed by silver and copper has lattice distortion and dislocation interactions, which can hinder the initiation and propagation of cracks. The film has a dense structure and does not undergo phase change or embrittlement at low temperatures, allowing the lubricating film to maintain its mechanical and lubricating properties in ultra-low temperature environments. Furthermore, the present invention enhances the bonding strength between the lubricating film and the substrate by providing a Ni bonding layer, improves the film's load-bearing capacity by providing a Ni-Cu bearing layer, and enhances the film's interlayer bonding strength and mechanical properties by providing a Cu-Ag gradient layer. In summary, the gradient multilayer Cu-Ag composite lubricating film provided by the present invention has excellent lubrication, wear resistance, and load-bearing capacity. It also exhibits strong bonding with the substrate and is adaptable to ultra-low temperature (<100K) service environments. It can be applied to the surface lubrication of moving contact parts in equipment such as rocket engines, superconducting coils, compressors, and space equipment, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a cross-sectional view of the gradient multilayer Cu-Ag composite lubricating film prepared in Example 2;
[0023] Figure 2 This is the XRD pattern of the gradient multilayer Cu-Ag composite lubricating film prepared in Example 2;
[0024] Figure 3 The friction coefficient of the gradient multilayer Cu-Ag composite film prepared in Example 2 changes with time at ultra-low temperatures (50K, 80K) (a) and the wear scar depth of the film after friction (b);
[0025] Figure 4 These are the bonding strength test results of the gradient multilayer Cu-Ag composite lubricating films prepared in Examples 1 to 3. DETAILED DESCRIPTION
[0026] The present invention provides a gradient multilayer Cu-Ag composite lubricating film, which comprises, from bottom to top, a Ni bonding layer, a Ni-Cu bearing layer, a Cu-Ag gradient layer and an Ag functional lubricating layer; the components of the Ni-Cu bearing layer include Ni and Cu, and the content of Cu gradually increases from bottom to top; the components of the Cu-Ag gradient layer include Cu and Ag, and the content of Ag gradually increases from bottom to top.
[0027] In the present invention, the thickness of the Ni bonding layer is preferably 200-400 nm, specifically 200 nm, 220 nm or 300 nm; the thickness of the Ni-Cu bearing layer is preferably 300-800 nm, specifically 400 nm, 420 nm or 500 nm; the thickness of the Cu-Ag gradient layer is preferably 400-1000 nm, specifically 500 nm, 800 nm or 1000 nm; the thickness of the Ag functional lubricating layer is preferably 400-1000 nm, specifically 600 nm, 800 nm or 1000 nm.
[0028] The present invention also provides a method for preparing the gradient multilayer Cu-Ag composite lubricating film described in the above scheme, comprising the following steps:
[0029] Using a Ni target, a first sputtering is performed on the substrate surface to obtain a Ni bonding layer;
[0030] Using a Ni target and a Cu target, a second sputtering is performed on the surface of the Ni bonding layer to obtain a Ni-Cu supporting layer; during the second sputtering, the sputtering current of the Cu target is gradually increased;
[0031] Using a Cu target and an Ag target, a third sputtering is performed on the surface of the Ni-Cu bearing layer to obtain a Cu-Ag gradient layer; during the third sputtering, the sputtering current of the Ag target gradually increases;
[0032] A fourth sputtering process is performed on the surface of the Cu-Ag gradient layer using an Ag target to obtain an Ag functional lubricating layer.
[0033] The present invention adopts a Ni target and performs a first sputtering on the surface of the substrate to obtain a Ni bonding layer. In the present invention, the material of the substrate is preferably metal, specifically steel or titanium alloy, the steel can be stainless steel or bearing steel; the titanium alloy can be TC4 titanium alloy; before the first sputtering, it is preferred to further include cleaning the substrate and plasma cleaning; the cleaning includes: ultrasonic cleaning the substrate in petroleum ether and acetone in turn; the time for ultrasonic cleaning in petroleum ether is preferably 10 to 30 minutes, specifically 15 minutes, 20 minutes or 30 minutes, and the time for ultrasonic cleaning in acetone is preferably 10 to 30 minutes, specifically 15 minutes, 20 minutes or 30 minutes. The conditions for the plasma cleaning preferably include: vacuum degree ≤ 2×10 -3 Pa, specifically 0.8×10 -3 Pa, 1×10 -3 Pa or 1.5×10 -3 Pa, the substrate rotation speed is 2 to 4 rpm, specifically 2 rpm, 3 rpm or 4 rpm, the cleaning gas is argon, the deposition gas pressure is 1 to 2 Pa, specifically 1 Pa, 1.5 Pa or 2 Pa, the substrate negative bias voltage is 600 to 800 V, specifically 600 V, 700 V or 800 V, and the plasma cleaning time is 30 to 40 min.
[0034] In the present invention, a closed magnetic field-multi-target co-sputtering deposition method is preferably used to prepare the gradient multilayer Cu-Ag composite lubricating film of the present invention. The target materials used in the closed magnetic field-multi-target co-sputtering deposition method include Ni target, Cu target and Ag target, among which the number of Ni target is preferably 1, the number of Cu target is preferably 1, and the number of Ag target is preferably 1 to 2, more preferably 2; in the subsequent sputtering process, the target material used can be selected according to the composition of the target layer.
[0035] In a specific embodiment of the present invention, the cleaned substrate is preferably transferred to the interior of a closed magnetic field-multi-target co-sputtering vacuum deposition chamber and fixed on a sample holder. The sample holder is connected to a negative bias power supply, and the vacuum deposition chamber is evacuated to ≤2×10 -3 Pa, the substrate being plated is rotated at a speed of 2 to 4 revolutions per minute, and then high-purity argon gas is introduced, and plasma cleaning is performed under the above-mentioned deposition gas pressure and substrate negative bias conditions. The present invention removes impurities and contaminants remaining on the substrate surface through plasma cleaning and activates the substrate surface.
[0036] In the present invention, the conditions for the first sputtering preferably include: the sputtering gas is argon, the deposition gas pressure is 0.1-0.3 Pa, specifically 0.1 Pa, 0.2 Pa or 0.3 Pa, the sputtering current of the Ni target is 1-3 A, specifically 1 A, 2 A or 3 A, and the substrate negative bias voltage is 100-200 V, specifically 100 V, 150 V or 200 V. In a specific embodiment of the present invention, after the plasma cleaning is completed, the argon flow rate is preferably adjusted to control the deposition gas pressure to 0.1-0.3 Pa, and then the Ni target sputtering power supply is turned on, and the sputtering current and substrate negative bias voltage are adjusted within the above ranges to perform the first sputtering.
[0037] After the first sputtering is completed, the present invention uses a Ni target and a Cu target to perform a second sputtering on the surface of the Ni bonding layer to obtain a Ni-Cu bearing layer. In the present invention, the conditions for the second sputtering preferably include: the sputtering gas is argon, the deposition pressure is 0.1 to 0.3 Pa, specifically 0.1 Pa, 0.2 Pa or 0.3 Pa, the sputtering current of the Ni target is 1 to 3 A, specifically 1 A, 2 A or 3 A, the sputtering current of the Cu target gradually increases from 0 A to the maximum sputtering current, the maximum sputtering current of the Cu target is 1 to 3 A, specifically 1 A, 2 A or 3 A, and the substrate negative bias is 100 to 200 V, specifically 100 V, 150 V or 200 V. In a specific embodiment of the present invention, the deposition gas pressure, the sputtering current of the Ni target and the negative bias voltage of the substrate during the second sputtering are preferably consistent with those during the first sputtering; after the first sputtering is completed, it is preferred to keep the conditions of the first sputtering unchanged, turn on the sputtering power supply of the Cu target and gradually increase the current to perform the second sputtering; specifically, the sputtering current of the Cu target is 0A at the beginning of the second sputtering, and then linearly increases by 1 to 3A, and the second sputtering ends when the target current is reached.
[0038] After the second sputtering is completed, the present invention uses a Cu target and an Ag target to perform a third sputtering on the surface of the Ni-Cu supporting layer to obtain a Cu-Ag gradient layer; during the third sputtering process, the sputtering current of the Ag target gradually increases. In the present invention, the conditions of the third sputtering include: the sputtering gas is argon, the deposition pressure is 0.1 to 0.3 Pa, specifically 0.1 Pa, 0.2 Pa or 0.3 Pa, the sputtering current of the Cu target is 1 to 3 A, specifically 1 A, 2 A or 3 A, the sputtering current of the Ag target gradually increases from 0 to the maximum sputtering current, the maximum sputtering current of the Ag target is 2 to 4 A, specifically 2 A, 3 A or 4 A, and the substrate negative bias is 100 to 200 V, specifically 100 V, 150 V or 200 V. In a specific embodiment of the present invention, during the third sputtering, the deposition gas pressure, the negative bias voltage of the substrate and the sputtering current of the Cu target are preferably consistent with those during the second sputtering. After the second sputtering is completed, the present invention preferably turns off the sputtering power supply of the Ni target, keeps the sputtering current of the Cu target unchanged, and then turns on the sputtering power supply of the Ag target to gradually increase the current for the third sputtering; specifically, the sputtering current of the Ag target is 0A at the beginning of the third sputtering, and then increases linearly by 2 to 4A. After reaching the target current, the third sputtering ends.
[0039] After the third sputtering is completed, the present invention uses an Ag target to perform a fourth sputtering on the surface of the Cu-Ag gradient layer to obtain an Ag functional lubricating layer. In the present invention, the conditions for the fourth sputtering preferably include: the sputtering gas is argon, the deposition pressure is 0.1 to 0.3 Pa, specifically 0.1 Pa, 0.2 Pa or 0.3 Pa, the sputtering current of the Ag target is 2 to 4 A, specifically 2 A, 3 A or 4 A, and the substrate negative bias is 100 to 200 V, specifically 100 V, 150 V or 200 V. In a specific embodiment of the present invention, the deposition pressure and the substrate negative bias during the fourth sputtering are preferably consistent with those during the third sputtering; after the third sputtering is completed, it is preferred to turn off the sputtering power supply of the Cu target, keep other conditions unchanged, and perform the fourth sputtering.
[0040] The present invention also provides the use of the gradient multilayer Cu-Ag composite lubricating film described in the above scheme or the gradient multilayer Cu-Ag composite lubricating film prepared by the preparation method described in the above scheme in an ultra-low temperature environment; the temperature of the ultra-low temperature environment is <100K, specifically 50K or 80K; the ultra-low temperature environment is preferably a vacuum environment, and the vacuum degree of the vacuum environment is preferably <1×10 -3 In a specific embodiment of the present invention, the gradient multilayer Cu-Ag composite lubricating film can be used as a surface lubricating film for moving contact parts serving in ultra-low temperature environments, such as moving contact parts in rocket engines, superconducting coils, compressors, space equipment, and the like.
[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0042] Example 1
[0043] (1) The stainless steel substrate was ultrasonically cleaned in petroleum ether and acetone for 30 min respectively, and then moved into a closed magnetic field-multi-target co-sputtering deposition vacuum chamber and fixed on a sample holder connected to a negative bias power supply;
[0044] (2) Evacuate the vacuum deposition chamber to 1.5×10 -3 The stainless steel substrate was rotated at a speed of 4 rpm; high-purity argon gas was introduced, the deposition pressure was controlled at 2.0 Pa, a negative bias voltage of 800 V was applied to the stainless steel substrate, and plasma cleaning was performed for 30 minutes to remove impurities and contaminants remaining on the surface of the stainless steel substrate;
[0045] (3) Adjust the argon flow rate, control the deposition pressure to 0.3 Pa, turn on the Ni target sputtering power supply, control the sputtering current to 3 A, adjust the substrate negative bias voltage to 200 V, and deposit the Ni bonding layer with a thickness of 400 nm;
[0046] (4) Keeping the above conditions unchanged, turn on the Cu target sputtering power supply, gradually increase the sputtering current from 0 to 3A, and deposit a Ni-Cu bearing layer with a thickness of 800nm.
[0047] (5) Turn off the Ni target sputtering power supply; keep the sputtering current of the Cu target at 3A, keep other conditions unchanged, turn on the Ag target sputtering power supply, and gradually increase the sputtering current from 0 to 4A to deposit a Cu-Ag gradient layer with a thickness of 1000nm.
[0048] (6) Turn off the Cu target sputtering power supply, maintain the sputtering current of the Ag target at 4 A, keep other conditions unchanged, and deposit the Ag functional lubricating layer with a thickness of 1000 nm.
[0049] The properties of the obtained composite lubricating film are as follows: film thickness 3.2 μm, friction coefficient 0.19 at 50 K, wear rate 1.2×10 -6 mm 3 / Nm.
[0050] Example 2
[0051] (1) The bearing steel substrate was ultrasonically cleaned in petroleum ether and acetone for 15 min respectively, and then moved into a closed magnetic field-multi-target co-sputtering deposition vacuum chamber and fixed on a sample holder connected to a negative bias power supply;
[0052] (2) Evacuate the vacuum deposition chamber to 1.0×10 -3 Pa; the bearing steel substrate was rotated at a speed of 2 rpm; high-purity argon gas was introduced, and the deposition pressure was controlled at 1 Pa. A negative bias voltage of 600 V was applied to the bearing steel substrate, and plasma cleaning was performed for 40 minutes to remove impurities and contaminants remaining on the substrate surface;
[0053] (3) Adjust the argon flow rate, control the deposition pressure to 0.1 Pa, turn on the Ni target sputtering power supply, control the sputtering current to 1.0 A, adjust the substrate negative bias voltage to 100 V, and deposit the Ni bonding layer with a thickness of 220 nm;
[0054] (4) Keeping the above conditions unchanged, turn on the Cu target sputtering power supply, gradually increase the sputtering current from 0 to 1A, and deposit the Ni-Cu supporting layer with a thickness of 420nm.
[0055] (5) Turn off the Ni target sputtering power supply; keep the sputtering current of the Cu target at 1A, and keep other conditions unchanged. Turn on the Ag target sputtering power supply, and gradually increase the sputtering current from 0 to 2A. The thickness of the deposited Cu-Ag gradient layer is 500nm.
[0056] (6) Turn off the Cu target sputtering power supply, keep the sputtering current of the Ag target at 2A, and keep other conditions unchanged. The thickness of the deposited Ag functional lubricating layer is 600nm.
[0057] The properties of the obtained composite lubricating film are as follows: film thickness 1.74 μm, friction coefficient 0.214 at 50 K, wear rate 1.5×10 -6 mm 3 / Nm.
[0058] Example 3
[0059] (1) The TC4 titanium alloy substrate was ultrasonically cleaned in petroleum ether and acetone for 20 min respectively, and then moved into a closed magnetic field-multi-target co-sputtering deposition vacuum chamber and fixed on a sample holder connected to a negative bias power supply;
[0060] (2) Evacuate the vacuum deposition chamber to 0.8×10 -3 Pa; the TC4 titanium alloy substrate was rotated at a speed of 3 rpm; high-purity argon gas was introduced, and the deposition pressure was controlled at 1.5 Pa. A negative bias voltage of 700 V was applied to the bearing steel substrate, and plasma cleaning was performed for 40 minutes to remove impurities and contaminants remaining on the substrate surface;
[0061] (3) Adjust the argon flow rate, control the deposition pressure to 0.2 Pa, turn on the Ni target sputtering power supply, control the sputtering current to 2.0 A, adjust the substrate negative bias voltage to 150 V, and deposit a Ni bonding layer with a thickness of 300 nm;
[0062] (4) Keeping the above conditions unchanged, turn on the Cu target sputtering power supply, gradually increase the sputtering current from 0 to 2A, and deposit a Ni-Cu bearing layer with a thickness of 500nm.
[0063] (5) Turn off the Ni target sputtering power supply; keep the sputtering current of the Cu target at 2A, keep other conditions unchanged, turn on the Ag target sputtering power supply, and gradually increase the sputtering current from 0 to 3A. The thickness of the deposited Cu-Ag gradient layer is 800nm.
[0064] (6) Turn off the Cu target sputtering power supply, maintain the sputtering current of the Ag target at 3A, keep other conditions unchanged, and deposit the Ag functional lubricating layer with a thickness of 800nm.
[0065] The properties of the obtained composite lubricating film are as follows: film thickness 2.4 μm, friction coefficient 0.23 at 80 K, wear rate 2.9×10 -6 mm 3 / Nm.
[0066] Performance Testing
[0067] (1) Structural characterization
[0068] The cross section of the gradient multilayer Cu-Ag composite lubricating film prepared in Example 2 was characterized using high-resolution transmission electron microscopy. Figure 1 As shown. Figure 1 It can be seen that the gradient multilayer Cu-Ag composite lubricating film provided by the present invention comprises a Ni bonding layer, a Ni-Cu bearing layer, a Cu-Ag gradient layer and an Ag functional lubricating layer from the inside to the outside of the substrate surface.
[0069] The gradient multilayer Cu-Ag composite lubricating film prepared in Example 2 was characterized by X-ray diffraction (XRD). Figure 2 As shown. Figure 2 It can be seen that in the composite lubricating film of the present invention, copper and silver form a face-centered cubic structure in the form of single elements.
[0070] (2) Tribological performance test
[0071] The tribological properties of the gradient multilayer Cu-Ag composite lubricating film prepared in Example 2 were tested at ultra-low temperature. The specific testing method was as follows: a vacuum ultra-low temperature ball-disc friction tester was used with a vacuum degree of <1×10 -3Pa, the temperature is controlled at 50K and 80K by GM refrigerator, the friction pair is Φ6mm GCr15 steel ball, the contact pressure is 5N, the rotation friction speed is 120rpm / min, the friction time is 1h, and the test results are as follows Figure 3 As shown. Figure 3 It can be seen that at the super-temperature of 50K, the friction coefficient of the composite lubricating film in the stable stage is 0.214, the wear depth is 280nm, and the corresponding wear rate is 1.5×10 -6 mm 3 / Nm; at an ultra-low temperature of 80K, the friction coefficient of the composite lubricating film in the stable stage is 0.23. This shows that the gradient multilayer Cu-Ag composite lubricating film of the present invention has good lubrication and wear resistance at ultra-low temperatures.
[0072] Under the same conditions, the tribological properties of the composite lubricating films prepared in Example 1 and Example 3 were tested at ultra-low temperatures. The results showed that the composite lubricating film prepared in Example 1 had a friction coefficient of 0.19 and a wear rate of 1.2×10 - 6 mm 3 / Nm, the composite lubricating film prepared in Example 3 has a friction coefficient of 0.23 and a wear rate of 2.9×10 -6 mm 3 / Nm.
[0073] (3) Adhesion performance test
[0074] The adhesion test of the gradient multilayer Cu-Ag composite lubricating film prepared in Examples 1 to 3 was carried out as follows: the scratch test was carried out at room temperature and atmospheric environment, the scratch tip was a φ200μm diamond tip, the loading range was (0.5-30)N, the scratch length was 5mm, and the loading rate was 14.75N / min. The test results are shown in Figure 2. Figure 4 As shown. Figure 4 It can be seen from the scratch morphology that the gradient multilayer Cu-Ag composite lubricating film has very good bonding strength, and there is no peeling and cracking in the scratch area and scratch edge, indicating that the design of the gradient multilayer structure gives the multilayer film very good mechanical properties.
[0075] In summary, the present invention utilizes a closed magnetic field-multi-target co-sputtering deposition technique, using one Ni target, one Cu target, and two Ag targets as sputtering targets, and argon as the sputtering gas source, to prepare a gradient multilayer Cu-Ag composite lubricating film. By varying the sputtering current of the Cu target and the sputtering current of the Ag target, a gradient multilayer composite film with a Ni-Cu bearing layer and Cu-Ag is prepared. The gradient multilayer structure effectively improves the film's bonding strength, load-bearing capacity, and wear resistance. The resulting film exhibits excellent self-lubrication and wear resistance at ultra-low temperatures, and can be used for surface lubrication of moving contact parts in equipment such as rocket engines, superconducting coils, compressors, and space equipment, proving to be a promising candidate for application.
[0076] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.
Claims
1. A gradient multilayer Cu-Ag composite lubricating film, characterized in that: From bottom to top, it includes a Ni bonding layer, a Ni-Cu bearing layer, a Cu-Ag gradient layer and an Ag functional lubricating layer; the components of the Ni-Cu bearing layer include Ni and Cu, and the Cu content gradually increases from bottom to top; the components of the Cu-Ag gradient layer include Cu and Ag, and the Ag content gradually increases from bottom to top.
2. The gradient multilayer Cu-Ag composite lubricating film according to claim 1, characterized in that: The thickness of the Ni-Cu bearing layer is 300-800 nm; the thickness of the Cu-Ag gradient layer is 400-1000 nm.
3. The gradient multilayer Cu-Ag composite lubricating film according to claim 1, characterized in that: The thickness of the Ni bonding layer is 200-400 nm; the thickness of the Ag functional lubricating layer is 400-1000 nm.
4. The method for preparing the gradient multilayer Cu-Ag composite lubricating film according to any one of claims 1 to 3, characterized in that: The following steps are involved: Using a Ni target, a first sputtering is performed on the substrate surface to obtain a Ni bonding layer; Using a Ni target and a Cu target, a second sputtering is performed on the surface of the Ni bonding layer to obtain a Ni-Cu supporting layer; during the second sputtering, the sputtering current of the Cu target is gradually increased; Using a Cu target and an Ag target, a third sputtering is performed on the surface of the Ni-Cu bearing layer to obtain a Cu-Ag gradient layer; during the third sputtering, the sputtering current of the Ag target gradually increases; A fourth sputtering process is performed on the surface of the Cu-Ag gradient layer using an Ag target to obtain an Ag functional lubricating layer.
5. The preparation method according to claim 4, characterized in that Before the first sputtering, the substrate is cleaned and plasma cleaned; The cleaning comprises: ultrasonically cleaning the substrate in petroleum ether and acetone in sequence; The plasma cleaning conditions include: vacuum degree ≤ 2×10 -3 Pa, substrate rotation speed is 2 to 4 rpm, cleaning gas is argon, deposition gas pressure is 1 to 2 Pa, substrate negative bias voltage is 600 to 800 V, and cleaning time is 30 to 40 min.
6. The preparation method according to claim 4, characterized in that The first sputtering conditions include: the sputtering gas is argon, the deposition gas pressure is 0.1-0.3 Pa, the sputtering current of the Ni target is 1-3 A, and the substrate negative bias voltage is 100-200 V.
7. The preparation method according to claim 4, characterized in that The conditions for the second sputtering include: the sputtering gas is argon, the deposition gas pressure is 0.1~0.3Pa, the sputtering current of the Ni target is 1~3A, the sputtering current of the Cu target gradually increases from 0 to the maximum sputtering current, the maximum sputtering current of the Cu target is 1~3A, and the substrate negative bias is 100~200V.
8. The preparation method according to claim 4, characterized in that The conditions for the third sputtering include: the sputtering gas is argon, the deposition gas pressure is 0.1~0.3Pa, the sputtering current of the Cu target is 1~3A, the sputtering current of the Ag target gradually increases from 0 to the maximum sputtering current, the maximum sputtering current of the Ag target is 2~4A, and the substrate negative bias is 100~200V.
9. The preparation method according to claim 4, characterized in that The fourth sputtering conditions include: the sputtering gas is argon, the deposition gas pressure is 0.1-0.3 Pa, the sputtering current of the Ag target is 2-4 A, and the substrate negative bias voltage is 100-200 V.
10. Use of the gradient multilayer Cu-Ag composite lubricating film according to any one of claims 1 to 3 or the gradient multilayer Cu-Ag composite lubricating film prepared by the preparation method according to any one of claims 4 to 9 in an ultra-low temperature environment, characterized in that: The temperature of the ultra-low temperature environment is less than 100K.