MoCN-cu self-lubricating composite coating, and preparation method and application thereof

Abstract

The application discloses a MoCN-Cu self-lubricating composite coating which is composed of a MoN adhesive layer, a MoCN gradient layer and a MoCN-Cu functional layer, and has a phase composition of polycrystal wrapping amorphous carbon structure and free Cu metal composite phase; the composite coating is prepared by arc ion plating deposition on a substrate matrix, and is applied to engine parts, matching parts, servo systems and attitude control systems. In the composite coating, the MoN adhesive layer, the MoCN gradient layer and the MoCN-Cu functional layer are sequentially arranged, and the phase composition is controlled to be polycrystal wrapping amorphous carbon structure and free Cu metal composite phase, so that the wear-resistant high-load-bearing performance of MoN is combined with the excellent self-lubricating performance of amorphous carbon material and soft metal phase Cu, a solid MoCN-Cu self-lubricating composite coating with low friction, low wear and high load-bearing is obtained, and the composite coating is suitable for use in a high friction and wear environment; and the preparation method is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of self-lubricating coating materials technology, specifically relating to a MoCN-Cu self-lubricating composite coating, its preparation method, and its application. Background Technology

[0002] Wear failure is a major cause of material and component failure in engineering applications. Employing advanced lubrication materials and technologies is an effective way to reduce wear. For high-tech equipment such as aerospace equipment, due to extremely harsh operating conditions, including alternating high / low temperatures and high vacuum environments, traditional lubricating greases are no longer suitable. High-temperature solid self-lubricating coatings possess excellent mechanical and tribological properties, meeting the performance requirements of self-lubricating coatings in the aerospace field and providing a new approach to the design and manufacturing of long-life, high-reliability engineering equipment. Applying high-temperature solid lubricating coatings to engine components, mating parts, and aerospace fasteners can effectively solve phenomena such as high-temperature sintering, seizing, and locking.

[0003] Currently, widely used solid lubricants include MoS2, WS2, and Ag, but they are prone to oxidation and failure under long-term high-temperature use. DLC (diamond-like carbon) films suffer from high internal stress and poor thermal stability, limiting their application in high-temperature environments above 300℃. Mo-N-based coating materials can generate a layered MoO3 lubricating phase during friction, exhibiting excellent high-temperature lubrication performance. Furthermore, they possess superior mechanical properties and chemical stability, demonstrating broad application prospects in the field of self-lubrication.

[0004] There are many methods for preparing Mo-N-based self-lubricating coatings, such as sintering, spraying, and laser cladding, but these methods only produce coatings with thicknesses in the millimeter range. However, precision parts such as aerospace fasteners and mating components require coatings with micrometer-level thicknesses, high uniformity, and strong adhesion, making these traditional methods unsuitable. High-temperature solid self-lubricating coatings for aerospace applications, prepared using arc ion plating technology, offer advantages such as fast deposition rates, good wear and corrosion resistance, low friction coefficient, and high film-substrate adhesion. Currently, there is an urgent need to develop new materials and methods with even higher overall performance to better meet the demanding service conditions. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a MoCN-Cu self-lubricating composite coating. This composite coating comprises a MoN binder layer, a MoCN gradient layer, and a MoCN-Cu functional layer, with the phase composition controlled to be a polycrystalline encapsulated amorphous carbon structure and a free Cu metal composite phase. This combines the wear-resistant and high load-bearing properties of MoN with the excellent self-lubricating properties of amorphous carbon materials and the soft metallic phase Cu, resulting in a solid MoCN-Cu self-lubricating composite coating that exhibits low friction, low wear, and high load-bearing capacity. This solves the problem of the lack of micron-thick self-lubricating coatings with high overall performance in the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a MoCN-Cu self-lubricating composite coating, characterized in that it is composed of a MoN binder layer, a MoCN gradient layer and a MoCN-Cu functional layer, and the phase composition of the MoCN-Cu self-lubricating composite coating is a polycrystalline encapsulated amorphous carbon structure and a free Cu metal composite phase; the content of each element in the MoCN-Cu functional layer, by atomic percentage, is: Cu 1.0%~8.2%, Mo 35.6%~53.5%, C 19.2%~27.5%, N 26.3%~36.8%.

[0007] The above-mentioned MoCN-Cu self-lubricating composite coating is characterized in that the thickness of the MoCN-Cu self-lubricating composite coating is 2.0μm~5.0μm, wherein the thickness of the MoN binder layer is 0.2μm~0.5μm, the thickness of the MoCN gradient layer is 0.3μm~0.5μm, and the thickness of the MoCN-Cu functional layer is 1.5μm~4μm. The MoCN-Cu self-lubricating composite coating of this invention is suitable for precision components. Essentially a soft-based hard-film system, it experiences wear and consumption during friction. Therefore, by controlling the thickness of the MoCN-Cu self-lubricating composite coating, its low-friction, low-wear, and high-load-bearing self-lubricating properties can be ensured. This avoids situations where the film layer is too thin, failing to meet the service life and load-bearing capacity requirements of the composite coating, or where the film layer is too thick, leading to stress concentration and peeling. It also avoids the problem of increased carbon content causing increased brittleness in the composite coating. By controlling the thickness of the MoN binder layer and the MoCN gradient layer in the composite coating, the MoCN-Cu self-lubricating composite coating of the aforementioned thickness is ensured to have good toughness and low internal stress, which is beneficial for improving the adhesion and thermal shock resistance of the composite coating.

[0008] In addition, the present invention also discloses a method for preparing the MoCN-Cu self-lubricating composite coating as described above, characterized in that the MoCN-Cu self-lubricating composite coating is prepared by arc ion plating on a substrate, and the method specifically includes the following steps:

[0009] Step 1: The substrate is ultrasonically cleaned sequentially with ethanol and acetone for 10-30 minutes, dried with an air gun, and then fixed onto the deposition stage in the arc ion plating chamber of the equipment using a clamp. A vacuum of 5.0 × 10⁻⁶ is then applied. -3 Pa ~ 7.0 × 10 -3 Pa, adjust the base station revolution speed to 10rpm~30rpm, and the sputtering temperature of the coating chamber to 200℃~400℃;

[0010] Step 2: Introduce working gases Ar and N2 into the coating chamber and control the volume flow rate ratio to be 10:3~10:9. Then select a Mo target, adjust the total gas pressure to 1.0Pa~2.0Pa, the Mo target current to 80A~120A, and the deposition time to 10min~30min. Use arc ion plating to deposit a MoN bonding layer on the substrate.

[0011] Step 3: Continue to introduce working gases Ar, N2 and C2H2 into the coating chamber, and control the volume flow rate ratio to be 10:3:1~10:9:3. Then select a Mo target, adjust the total gas pressure to 1.0Pa~2.5Pa, the Mo target current to 80A~120A, and the deposition time to 10min~30min. Use arc ion plating to deposit a MoCN gradient layer on the MoN bonding layer in step 2.

[0012] Step 4: Continue to introduce working gases Ar, N2, and C2H2 into the coating chamber, and control the volume flow rate ratio to be 10:3:1~10:9:3. Then select Mo and Cu targets, adjust the total gas pressure to 1.0 Pa~2.5 Pa, the Mo target current to 80 A~120 A, the Cu target current to 10 A~30 A, and the deposition time to 120 min~160 min. Use arc ion plating with the assistance of a rotating platform to deposit a MoCN-Cu functional layer on the MoCN gradient layer in Step 3, thereby obtaining a MoCN-Cu self-lubricating composite coating on the substrate.

[0013] The method described above is characterized in that the substrate in step one is single-crystal silicon, alloy steel, or titanium alloy. The MoCN-Cu self-lubricating composite coating prepared by this invention is suitable for various common substrates and has excellent applicability.

[0014] The above method is characterized in that, when the volumetric flow rate ratio in step two is less than 10:7, the MoN binder layer has a two-phase coexistence structure of hcp-MoN and fcc-Mo2N; when the volumetric flow rate ratio in step two is greater than 10:7, the MoN binder layer has a single-phase structure of fcc-Mo2N. During the research process of this invention, it was discovered that MoN... xThe adhesive layer generally contains four phases: Mo, MoN solid solution, fcc-Mo2N, and hcp-MoN. Different phase compositions and structures will affect the hardness, roughness, and friction coefficient of the MoN adhesive layer. Based on this, the present invention controls the inlet volume flow rate ratio of Ar and N2, i.e., the argon-nitrogen ratio. A lower argon-nitrogen ratio is used to provide more N atoms to react with sputtered Mo atoms. Since the atomic ratio of Mo to N in hcp-MoN is smaller than that in fcc-Mo2N, a large amount of hcp-MoN is easily generated under the lower argon-nitrogen ratio condition, forming a two-phase coexistence structure of hcp-MoN and fcc-Mo2N. Compared with fcc-Mo2N, hcp-MoN has lower hardness and higher friction coefficient, which reduces the hardness of the MoN adhesive layer and significantly increases the friction coefficient. When a higher argon-nitrogen ratio is used, there are not enough N atoms to react with the sputtered Mo atoms after they reach the substrate, which easily generates a single phase of fcc-Mo2N. The N deficiency in the single phase of fcc-Mo2N results in a rough and non-dense surface of the MoN adhesive layer with defects such as protrusions. Therefore, by selecting an appropriate argon-nitrogen ratio, this invention obtains a MoN bonding layer with high hardness, low friction coefficient, and dense surface roughness, thereby obtaining a MoCN-Cu self-lubricating composite coating with good overall performance to meet the application requirements.

[0015] The method described above is characterized in that the Cu target in step four is replaced with a MoCu alloy target.

[0016] The above method is characterized in that, during the deposition process in step four, the free-state metallic copper nanoparticles are distributed at the MoN / Mo2N boundary in the MoCN-Cu functional layer. In the MoCN-Cu self-lubricating composite coating of the present invention, the phase structure of the MoCN-Cu functional layer, the MoN binder layer, and the MoCN gradient layer is consistent, and it also contains both MoN and Mo2N phases. Since the soft metallic Cu doped with MoCN in the MoCN-Cu functional layer cannot form a stable ceramic phase with the matrix, Cu exists in a free form and is uniformly distributed at the boundary of the MoN / Mo2N phases. When the hard MoN / Mo2N phase is surrounded by the soft Cu phase distributed at the boundary, it is connected by deformation or toughness of the soft Cu phase, thus playing the role of a toughening coating and improving the toughness of the composite coating.

[0017] The above method is characterized in that the MoCN-Cu self-lubricating composite coating in step four has a hardness of 2100HV~2800HV, an adhesion force to the substrate of 50N~58N, and under dry friction conditions, a room temperature sliding friction coefficient of less than 0.45 and a wear rate of 0.86×10⁻⁶. -7 mm 3 / N·m ~1.21×10 -7 mm 3 / N·m, with a sliding friction coefficient of less than 0.40 at a high temperature of 500℃, and a wear rate of 4.5×10 -6 mm 3 / N·m ~15.3×10 -6 mm 3 / N·m.

[0018] This invention also discloses an application of the MoCN-Cu self-lubricating composite coating as described above, characterized in that the MoCN-Cu self-lubricating composite coating is applied to engine components, mating components, servo systems, and attitude control systems. The MoCN-Cu self-lubricating composite coating of this invention exhibits low friction, low wear, and high load-bearing capacity, effectively solving the problems of high-temperature sintering, jamming, and seizing in the aforementioned applications, thus ensuring operational stability.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The MoCN-Cu self-lubricating composite coating of the present invention comprises a MoN binder layer, a MoCN gradient layer, and a MoCN-Cu functional layer, and controls the phase composition to be a polycrystalline encapsulated amorphous carbon structure and a free Cu metal composite phase. This combines the wear-resistant and high load-bearing performance of MoN with the excellent self-lubricating properties of amorphous carbon materials and soft metal phase Cu, resulting in a solid MoCN-Cu self-lubricating composite coating with low friction, low wear, and high load-bearing capacity. At the same time, by sequentially setting the MoN binder layer, the MoCN gradient layer, and the MoCN-Cu functional layer, a gradual transition from the substrate to the coating is achieved, improving the adhesion between the composite coating and the substrate.

[0021] 2. The MoCN-Cu composite self-lubricating coating composed of soft metal, amorphous carbon, and transition metal nitrides in this invention exhibits good lubrication performance at both room temperature and medium-high temperature. At room temperature, the introduction of Cu and amorphous carbon gives the composite self-lubricating coating excellent shear properties, which can separate two contacting sliding surfaces, thereby reducing friction and wear. At high temperatures, due to the synergistic lubrication effect of Cu and molybdenum salt, the coefficient of friction is significantly reduced, achieving a certain wide-temperature-range self-lubricating effect.

[0022] 3. This invention uses an arc ion plating method to sequentially prepare each layer and obtain a MoCN-Cu self-lubricating composite coating, which has a high ionization rate and a fast deposition rate, making it suitable for industrial production.

[0023] 4. The MoCN-Cu self-lubricating composite coating prepared by the present invention using the arc ion plating method is uniform and dense, with high hardness, low coefficient of friction, and excellent self-lubricating performance, making it suitable for use in high friction and wear environments.

[0024] 5. The MoCN-Cu self-lubricating composite coating prepared by this invention has a hardness greater than 2000 HV~2800 HV, a friction coefficient less than 0.45, and a wear rate of 0.86×10⁻⁶. -7 mm 3 N -1 m -1 ~1.21×10 -7 mm 3 N -1 m -1 The coefficient of sliding friction is less than 0.40 at a high temperature of 500℃, and the wear rate can reach 4.5×10 at room temperature of 25℃ and at a high temperature of 500℃. -6 mm 3 / N·m and 15.3×10 -6 mm 3 / N·m.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1a This is a surface SEM image of the MoCN-Cu self-lubricating composite coating prepared in Example 3 of the present invention.

[0027] Figure 1b This is a cross-sectional SEM image of the MoCN-Cu self-lubricating composite coating prepared in Example 3 of the present invention.

[0028] Figure 2 The image shows the scratch morphology of the MoCN-Cu self-lubricating composite coating prepared in Example 3 of this invention.

[0029] Figure 3 The graph shows the tribological and wear performance of the MoCN-Cu self-lubricating composite coating prepared in Example 3 of this invention at different temperatures.

[0030] Figure 4 The figures show the wear rate and microhardness test results of the MoCN-Cu self-lubricating composite coatings prepared in Examples 1-4 of this invention at 500℃. Detailed Implementation

[0031] Example 1

[0032] The MoCN-Cu self-lubricating composite coating of this embodiment consists of a MoN binder layer with a thickness of 0.2 μm, a MoCN gradient layer with a thickness of 0.3 μm, and a MoCN-Cu functional layer with a thickness of 1.5 μm. The phase composition of the MoCN-Cu self-lubricating composite coating is a two-phase coexistence structure of hcp-MoN and fcc-Mo2N encapsulating an amorphous carbon structure and a free Cu metal composite phase. The atomic percentage content of each element in the MoCN-Cu functional layer is: Cu 1.0%, Mo 53.5%, C 19.2%, N 26.3%.

[0033] The preparation method of the MoCN-Cu self-lubricating composite coating in this embodiment includes the following steps:

[0034] Step 1: The single-crystal silicon substrate is ultrasonically cleaned with ethanol and acetone for 10 minutes in sequence, dried with an air gun, and then fixed on the substrate in the coating chamber of the arc ion plating equipment using a clamp. A vacuum of 7.0 × 10⁻⁶ is then applied. -3 Pa, adjust the base station revolution speed to 10 rpm, and the sputtering temperature of the coating chamber to 200℃;

[0035] Step 2: Introduce Ar and N2 working gases with a volume purity of 99.99% into the coating chamber, and control the volume flow rate ratio to be 10:3. Then, select a Mo target with a mass purity of 99.95%, adjust the total gas pressure to 1.0 Pa, the Mo target current to 80 A, and the deposition time to 10 min. Use arc ion plating to deposit a MoN bonding layer with a thickness of 0.2 μm on the substrate.

[0036] Step 3: Continue to introduce working gases Ar, N2, and C2H2, all with a volume purity of 99.99%, into the coating chamber, and control the volume flow rate ratio to be 10:3:1. Then, select a Mo target with a mass purity of 99.95%, adjust the total gas pressure to 1.3 Pa, the Mo target current to 80 A, and the deposition time to 10 min. Use arc ion plating to deposit a MoCN gradient layer with a thickness of 0.3 μm on the MoN bonding layer from Step 2.

[0037] Step 4: Continue to introduce working gases Ar, N2, and C2H2, all with a volume purity of 99.99%, into the coating chamber, controlling the volume flow rate ratio to be 10:3:1. Then, select a Mo target with a mass purity of 99.95% and a Cu target with a mass purity of 99.9%, adjust the total gas pressure to 1.0 Pa, the Mo target current to 80 A, the Cu target current to 10 A, and the deposition time to 120 min. Use arc ion plating with an auxiliary rotating platform to ensure uniform distribution of Cu in the MoCN. Deposit a 1.5 μm thick MoCN-Cu functional layer on the MoCN gradient layer from Step 3, thereby obtaining a 2 μm thick MoCN-Cu self-lubricating composite coating on the substrate. During the deposition process, nanoparticles of free metallic copper are distributed at the MoN / Mo2N boundary in the MoCN-Cu functional layer.

[0038] Testing revealed that the MoCN-Cu self-lubricating composite coating prepared in this embodiment exhibits a two-phase coexistence structure of hcp-MoN and fcc-Mo2N; as shown... Figure 4 As shown, the microhardness of this MoCN-Cu self-lubricating composite coating at room temperature is 2183 HV, the adhesion force to the substrate is 50 N, and under dry friction conditions, the room temperature sliding friction coefficient is 0.43, and the wear rate is 0.86 × 10⁻⁶. -7 mm 3 The coefficient of sliding friction is 0.38 at 500℃, and the wear rate is 4.5×10⁻⁶ N·m. -6 mm 3 / N·m.

[0039] Example 2

[0040] The MoCN-Cu self-lubricating composite coating of this embodiment consists of a MoN binder layer with a thickness of 0.3 μm, a MoCN gradient layer with a thickness of 0.4 μm, and a MoCN-Cu functional layer with a thickness of 2.5 μm. The phase composition of the MoCN-Cu self-lubricating composite coating is a two-phase coexistence structure of hcp-MoN and fcc-Mo2N encapsulating an amorphous carbon structure and a free Cu metal composite phase. The atomic percentage content of each element in the MoCN-Cu functional layer is: Cu 3.5%, Mo 40.1%, C 27.5%, N 28.9%.

[0041] The preparation method of the MoCN-Cu self-lubricating composite coating in this embodiment includes the following steps:

[0042] Step 1: The alloy steel substrate is ultrasonically cleaned with ethanol and acetone for 20 minutes in sequence. After being dried with an air gun, it is fixed on the substrate in the coating chamber of the arc ion plating equipment using a clamp, and a vacuum of 6.0 × 10⁻⁶ is drawn. -3Pa, adjust the base station revolution speed to 20 rpm, and the sputtering temperature of the coating chamber to 300℃;

[0043] Step 2: Introduce Ar and N2 working gases with a volume purity of 99.99% into the coating chamber, and control the volume flow rate ratio to be 10:5. Then, select a Mo target with a mass purity of 99.95%, adjust the total gas pressure to 1.3 Pa, the Mo target current to 100 A, and the deposition time to 15 min. Use arc ion plating to deposit a MoN bonding layer with a thickness of 0.3 μm on the substrate.

[0044] Step 3: Continue to introduce working gases Ar, N2, and C2H2, all with a volume purity of 99.99%, into the coating chamber, and control the volume flow rate ratio to be 10:5:2. Then, select a Mo target with a mass purity of 99.95%, adjust the total gas pressure to 1.4 Pa, the Mo target current to 100 A, and the deposition time to 15 min. Use arc ion plating to deposit a MoCN gradient layer with a thickness of 0.4 μm on the MoN bonding layer from Step 2.

[0045] Step 4: Continue to introduce working gases Ar, N2, and C2H2, all with a volume purity of 99.99%, into the coating chamber, controlling the volume flow rate ratio to be 10:5:2. Then, select a Mo target with a mass purity of 99.95% and a Cu target with a mass purity of 99.9%, adjust the total gas pressure to 1.5 Pa, the Mo target current to 100 A, the Cu target current to 20 A, and the deposition time to 140 min. Use arc ion plating with an auxiliary rotating platform to ensure uniform Cu distribution in the MoCN. Deposit a 2.5 μm thick MoCN-Cu functional layer on the MoCN gradient layer from Step 3, thereby obtaining a 3.2 μm thick MoCN-Cu self-lubricating composite coating on the substrate. During the deposition process, nanoparticles of free metallic copper are distributed at the MoN / Mo2N boundary in the MoCN-Cu functional layer.

[0046] Testing revealed that the MoCN-Cu self-lubricating composite coating prepared in this embodiment exhibits a two-phase coexistence structure of hcp-MoN and fcc-Mo2N; as shown... Figure 4 As shown, the MoCN-Cu self-lubricating composite coating has a hardness of 2356 HV at room temperature, an adhesion force of 55 N to the substrate, and under dry friction conditions, a room temperature sliding friction coefficient of 0.40 and a wear rate of 1.21 × 10⁻⁶. -7 mm 3 The coefficient of sliding friction is 0.35 at 500℃, and the wear rate is 6.7×10⁻⁶ N·m. -6 mm 3 / N·m.

[0047] Example 3

[0048] The MoCN-Cu self-lubricating composite coating of this embodiment consists of a 0.5 μm thick MoN binder layer, a 0.5 μm thick MoCN gradient layer, and a 3.0 μm thick MoCN-Cu functional layer. The phase composition of the MoCN-Cu self-lubricating composite coating is a two-phase coexistence structure of hcp-MoN and fcc-Mo2N encapsulating an amorphous carbon structure and a free Cu metal composite phase. The atomic percentage content of each element in the MoCN-Cu functional layer is: Cu 6.1%, Mo 35.6%, C 21.5%, N 36.8%.

[0049] The preparation method of the MoCN-Cu self-lubricating composite coating in this embodiment includes the following steps:

[0050] Step 1: The titanium alloy substrate is ultrasonically cleaned with ethanol and acetone for 30 minutes in sequence. After being dried with an air gun, it is fixed on the substrate in the coating chamber of the arc ion plating equipment using a clamp, and a vacuum of 5.0 × 10⁻⁶ is drawn. -3 Pa, adjust the base station revolution speed to 30 rpm, and the sputtering temperature of the coating chamber to 400℃;

[0051] Step 2: Introduce working gases Ar and N2, both with a volume purity of 99.99%, into the coating chamber, and control the volume flow rate ratio to be 10:7. Then, select a Mo target with a mass purity of 99.95%, adjust the total gas pressure to 1.8 Pa, the Mo target current to 120 A, and the deposition time to 30 min. Use arc ion plating to deposit a MoN bonding layer with a thickness of 0.5 μm on the substrate.

[0052] Step 3: Continue to introduce working gases Ar, N2, and C2H2, all with a volume purity of 99.99%, into the coating chamber, and control the volume flow rate ratio to be 10:7:2. Then, select a Mo target with a mass purity of 99.95%, adjust the total gas pressure to 2.0 Pa, the Mo target current to 110 A, and the deposition time to 30 min. Use arc ion plating to deposit a MoCN gradient layer with a thickness of 0.5 μm on the MoN bonding layer from Step 2.

[0053] Step 4: Continue to introduce working gases Ar, N2, and C2H2, all with a volume purity of 99.99%, into the coating chamber, controlling the volume flow rate ratio to be 10:7:2. Then, select a Mo target with a mass purity of 99.95% and a Cu target with a mass purity of 99.9%, adjust the total gas pressure to 2.0 Pa, the Mo target current to 110 A, the Cu target current to 30 A, and the deposition time to 160 min. Use arc ion plating with an auxiliary rotating platform to ensure uniform distribution of Cu in the MoCN. Deposit a 3.0 μm thick MoCN-Cu functional layer on the MoCN gradient layer from Step 3, thereby obtaining a 4.0 μm thick MoCN-Cu self-lubricating composite coating on the substrate. During the deposition process, nanoparticles of free metallic copper are distributed at the MoN / Mo2N boundary in the MoCN-Cu functional layer.

[0054] Testing revealed that the MoCN-Cu self-lubricating composite coating prepared in this embodiment exhibits a two-phase coexistence structure of hcp-MoN and fcc-Mo2N; as shown... Figure 4 As shown, the MoCN-Cu self-lubricating composite coating has a hardness of 2789 HV at room temperature, an adhesion force of 78 N to the substrate, and under dry friction conditions, a room temperature sliding friction coefficient of 0.45 and a wear rate of 0.86 × 10⁻⁶. -7 mm 3 The coefficient of sliding friction is 0.33 at 500℃, and the wear rate is 9.5×10⁻⁶ N·m. -6 mm 3 / N·m.

[0055] Figure 1a Here is a surface SEM image of the MoCN-Cu self-lubricating composite coating prepared in this embodiment. Figure 1a It can be seen that the surface of the MoCN-Cu self-lubricating composite coating has a typical multi-arc ion plating morphology, with a small number of droplets on the surface and relatively small size.

[0056] Figure 1b This is a cross-sectional SEM image of the MoCN-Cu self-lubricating composite coating prepared in this embodiment. Figure 1b It can be seen that the total thickness of the MoCN-Cu self-lubricating composite coating is 4.0 μm, and the interface of the composite coating is dense and uniform, with no defects such as pores at the interface.

[0057] Figure 2 The image shows the scratch morphology of the MoCN-Cu self-lubricating composite coating prepared in this embodiment. Figure 2It can be seen that the critical load corresponding to the initial crack of the scratch is about 78N. A small amount of edge flaking occurred, but no brittle spalling occurred around the scratch. This indicates that the MoCN-Cu self-lubricating composite coating has good adhesion to the substrate and exhibits good film-substrate adhesion and toughness, which can meet the application requirements of the composite coating.

[0058] Figure 3 The graph shows the tribological properties of the MoCN-Cu self-lubricating composite coating prepared in this embodiment at different temperatures. Figure 3 It can be seen that the MoCN-Cu self-lubricating composite coating has a room temperature sliding friction coefficient of 0.45 and a wear rate of 0.86 × 10⁻⁶ under dry friction conditions. -7 mm 3 The coefficient of sliding friction is 0.33 at 500℃, and the wear rate is 9.5×10⁻⁶ N·m. - 6 mm 3 The coefficient of friction is N·m, indicating that the MoCN-Cu self-lubricating composite coating can maintain a low coefficient of friction at room temperature to 500℃, but the wear rate will increase under high temperature conditions.

[0059] Example 4

[0060] The MoCN-Cu self-lubricating composite coating of this embodiment consists of a 0.5 μm thick MoN binder layer, a 0.5 μm thick MoCN gradient layer, and a 4 μm thick MoCN-Cu functional layer. The phase composition of the MoCN-Cu self-lubricating composite coating is an hcp-MoN structure encapsulating an amorphous carbon structure and a free Cu metal composite phase. The atomic percentage content of each element in the MoCN-Cu functional layer is: Cu 8.2%, Mo 37.9%, C 24.1%, N 29.8%.

[0061] The preparation method of the MoCN-Cu self-lubricating composite coating in this embodiment includes the following steps:

[0062] Step 1: The titanium alloy substrate is ultrasonically cleaned with ethanol and acetone for 30 minutes in sequence. After being dried with an air gun, it is fixed on the substrate in the coating chamber of the arc ion plating equipment using a clamp, and a vacuum of 5.0 × 10⁻⁶ is drawn. -3 Pa, adjust the base station revolution speed to 30 rpm, and the sputtering temperature of the coating chamber to 300℃;

[0063] Step 2: Introduce working gases Ar and N2, both with a volume purity of 99.99%, into the coating chamber, and control the volume flow rate ratio to be 10:9. Then, select a Mo target with a mass purity of 99.95%, adjust the total gas pressure to 2.0 Pa, the Mo target current to 120 A, and the deposition time to 30 min. Use arc ion plating to deposit a MoN bonding layer with a thickness of 0.5 μm on the substrate.

[0064] Step 3: Continue to introduce working gases Ar, N2, and C2H2, all with a volume purity of 99.99%, into the coating chamber, and control the volume flow rate ratio to be 10:9:3. Then, select a Mo target with a mass purity of 99.95%, adjust the total gas pressure to 2.5 Pa, the Mo target current to 120 A, and the deposition time to 30 min. Use arc ion plating to deposit a MoCN gradient layer with a thickness of 0.5 μm on the MoN bonding layer from Step 2.

[0065] Step 4: Continue to introduce working gases Ar, N2, and C2H2, all with a volume purity of 99.99%, into the coating chamber, controlling the volume flow rate ratio to be 10:9:3. Then, select a Mo target with a mass purity of 99.95%, a Cu target with a mass purity of 99.9%, and a MoCu target with a mass content of 10%. Adjust the total gas pressure to 2.5 Pa, the Mo target current to 80 A, the MoCu target current to 40 A, and the deposition time to 160 min. Use arc ion plating with an auxiliary rotating platform to ensure uniform distribution of Cu in MoCN. Deposit a 4 μm thick MoCN-Cu functional layer on the MoCN gradient layer from Step 3, thereby obtaining a 5 μm thick MoCN-Cu self-lubricating composite coating on the substrate. During the deposition process, nanoparticles of free metallic copper are distributed at the MoN / Mo2N boundary in the MoCN-Cu functional layer.

[0066] Testing revealed that the MoCN-Cu self-lubricating composite coating prepared in this embodiment has an hcp-MoN structure; as shown... Figure 4 As shown, the MoCN-Cu self-lubricating composite coating has a hardness of 2626 HV, an adhesion strength to the substrate of 70 N, and under dry friction conditions, a room temperature sliding friction coefficient of 0.41 and a wear rate of 2.6 × 10⁻⁶. -7 mm 3 The coefficient of sliding friction is 0.30 at 500℃, and the wear rate is 15.3 × 10⁻⁶ N·m. -6 mm 3 / N·m.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A MoCN-Cu self-lubricating composite coating, characterized in that, The coating consists of a MoN binder layer, a MoCN gradient layer, and a MoCN-Cu functional layer. The phase composition of the MoCN-Cu self-lubricating composite coating is a polycrystalline encapsulated amorphous carbon structure and a free Cu metal composite phase. The atomic percentage content of each element in the MoCN-Cu functional layer is as follows: Cu 1.0%~8.2%, Mo 35.6%~53.5%, C 19.2%~27.5%, N 26.3%~36.8%. The MoCN-Cu self-lubricating composite coating is prepared by arc ion plating on a substrate, specifically including the following steps: Step 1: The substrate is ultrasonically cleaned sequentially with ethanol and acetone for 10-30 minutes, dried with an air gun, and then fixed onto the deposition stage in the arc ion plating chamber of the equipment using a clamp. A vacuum of 5.0 × 10⁻⁶ is then applied. -3 Pa ~ 7.0 × 10 - 3 Pa, adjust the base station revolution speed to 10rpm~30rpm, and the sputtering temperature of the coating chamber to 200℃~400℃; Step 2: Introduce working gases Ar and N2 into the coating chamber and control the volume flow rate ratio to be 10:3~10:

9. Then select a Mo target, adjust the total gas pressure to 1.0Pa~2.0Pa, the Mo target current to 80A~120A, and the deposition time to 10min~30min. Use arc ion plating to deposit a MoN bonding layer on the substrate. Step 3: Continue to introduce working gases Ar, N2 and C2H2 into the coating chamber, and control the volume flow rate ratio to be 10:3:1~10:9:

3. Then select a Mo target, adjust the total gas pressure to 1.0Pa~2.5Pa, the Mo target current to 80A~120A, and the deposition time to 10min~30min. Use arc ion plating to deposit a MoCN gradient layer on the MoN bonding layer in step 2. Step 4: Continue to introduce working gases Ar, N2, and C2H2 into the coating chamber, controlling the volumetric flow rate ratio to be 10:3:1 to 10:9:

3. Then, select Mo and Cu targets, adjust the total gas pressure to 1.0 Pa to 2.5 Pa, the Mo target current to 80 A to 120 A, the Cu target current to 10 A to 30 A, and the deposition time to 120 min to 160 min. Use arc ion plating with an auxiliary rotating platform to deposit the MoCN gradient layer from Step 3. A MoCN-Cu functional layer is formed, thereby obtaining a MoCN-Cu self-lubricating composite coating on the substrate. During the deposition process, nanoparticles of free metallic copper are distributed at the MoN / Mo2N boundary in the MoCN-Cu functional layer. The MoCN-Cu self-lubricating composite coating has a hardness of 2100 HV~2800 HV, an adhesion force to the substrate of 50 N~58 N, and under dry friction conditions, a room temperature sliding friction coefficient of less than 0.45 and a wear rate of 0.86 × 10⁻⁶. -7 mm 3 / (N·m)~1.21×10 -7 mm 3 / (N·m), the sliding friction coefficient is less than 0.40 at a high temperature of 500℃, and the wear rate is 4.5×10. -6 mm 3 / (N·m)~15.3×10 - 6 mm 3 / (N·m).

2. The MoCN-Cu self-lubricating composite coating according to claim 1, characterized in that, The thickness of the MoCN-Cu self-lubricating composite coating is 2.0 μm to 5.0 μm, wherein the thickness of the MoN binder layer is 0.2 μm to 0.5 μm, the thickness of the MoCN gradient layer is 0.3 μm to 0.5 μm, and the thickness of the MoCN-Cu functional layer is 1.5 μm to 4 μm.

3. The MoCN-Cu self-lubricating composite coating according to claim 1, characterized in that, The substrate mentioned in step one is monocrystalline silicon, alloy steel, or titanium alloy.

4. The MoCN-Cu self-lubricating composite coating according to claim 1, characterized in that, When the volumetric flow rate ratio described in step two is less than 10:7, the MoN binder layer has a two-phase coexistence structure of hcp-MoN and fcc-Mo2N; when the volumetric flow rate ratio described in step two is greater than 10:7, the MoN binder layer has a single-phase structure of fcc-Mo2N.

5. The MoCN-Cu self-lubricating composite coating according to claim 1, characterized in that, Replace the Cu target mentioned in step four with a MoCu alloy target.

6. An application of the MoCN-Cu self-lubricating composite coating as described in claim 1 or 2, characterized in that, This MoCN-Cu self-lubricating composite coating is applied to engine components, mating parts, servo systems, and attitude control systems.

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