Wear-resistant nano gradient composite coating and magnetron sputtering method thereof

Abstract

The application discloses a wear-resistant nanometer gradient composite coating and a magnetron sputtering method thereof, and belongs to the technical field of material surface treatment. The wear-resistant nanometer gradient composite coating is composed of oxide nanoparticles and a soft layer. The soft layer is coated on the outside of the oxide nanoparticles during friction. The oxide nanoparticles gradually decrease from the surface to the center of the coating, and the soft layer gradually increases from the surface to the center of the coating, forming a reverse composite gradient layer. The soft layer and the oxide nanoparticle layer are obtained through the magnetron sputtering method. The soft layer is composed of Ag and Cu soft metals. The oxide nanoparticles are Fe2O3 nanoparticles. The oxide nanoparticles have a bearing effect, and can reduce fretting wear of the material through rolling. The soft metal has a coating and bonding effect on the nanometer oxide particles. The wear-resistant nanometer gradient composite coating and the magnetron sputtering method thereof can solve the problem that the existing wear-resistant nanometer hard coating is easy to peel off, thereby affecting the service life of the coating.

Description

Technical Field

[0001] This invention relates to the field of material surface treatment technology, and in particular to a wear-resistant nano-gradient composite coating and its magnetron sputtering method. Background Technology

[0002] Fretting wear, the wear caused by relatively low-amplitude oscillating motion between two contact surfaces, is a recurring industrial problem. It occurs in critical components of high-end equipment such as aero-engines, automobiles, high-speed trains, ships, and power lines, including blade tenons, bolts, splines, wheel-rail journals, and cable contacts. Fretting wear can lead to seizing of critical components, power loss, increased noise, dimensional changes, and material loss. Therefore, improving the resistance of metal parts to fretting wear is crucial for the service reliability and service life of critical components in high-end equipment.

[0003] Surface modification or increased lubrication of parts are effective ways to fundamentally solve fretting wear. Common methods include adding liquid lubricants, surface work hardening, and surface coating with solid lubricants. Liquid lubricants are widely used to improve the wear performance of materials due to their good fluidity, ease of replenishment, and ability to remove wear debris. However, their low load-bearing capacity, high-temperature instability, and environmental pollution severely limit their application in fretting wear control. Surface work hardening techniques such as shot peening and rolling introduce residual compressive stress and form a surface hardening layer by impacting the component surface with energy. This can inhibit the initiation and slow the propagation of surface cracks. However, excessive modification by surface work hardening techniques can deteriorate the surface quality of the material. Surface coating with solid lubricants is considered a relatively friendly technique for improving components because it has outstanding chemical stability, high mechanical strength, and excellent wear resistance. Most importantly, solid lubricants can meet the lubrication requirements of some harsh working conditions. Therefore, surface coating with solid lubricants has become a major means of improving the resistance of metal components to fretting wear. While soft metals possess low shear stress and good self-lubricating properties, their low compressive strength makes them prone to wear under high loads. Hard Fe2O3 oxide nanoparticles exhibit high-pressure bearing capacity and rolling lubrication during fretting wear; however, their high brittleness leads to spalling, and their poor adhesion to the matrix restricts their application and development in the field of fretting wear research.

[0004] The inventors previously used a triboelectric processing method to prepare this self-lubricating layer to improve wear resistance. However, this method is inefficient, requires specially designed friction heads for complex-shaped parts, and is only suitable for relatively simple parts. Furthermore, controlling the thickness of the nano-oxide layer is difficult, and nano-oxides cannot be formed on soft metal surfaces through friction. This invention avoids these drawbacks by using magnetron sputtering to obtain composite coatings with different gradients and sequences. It features high preparation efficiency, convenient coating control, and excellent wear resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a wear-resistant nano-gradient composite coating and its magnetron sputtering method, which solves the problems of existing wear-resistant nano-hard coatings being prone to peeling, having low preparation efficiency, being difficult to implement on complex shaped parts, and affecting the wear resistance and service life of the coating.

[0006] To achieve the above objectives, the present invention provides a wear-resistant nano-gradient composite coating, which is composed of oxide nanoparticles and a soft layer. During the friction process, the soft layer coats the outside of the oxide nanoparticles. The number of oxide nanoparticles gradually decreases from the surface of the coating towards the center, while the number of soft layers gradually increases from the surface of the coating towards the center.

[0007] Preferably, the soft layer is a coating formed by one or two soft metals selected from Ag and Cu, and the oxide nanoparticles are Fe2O3 nanoparticles.

[0008] The soft layer serves two purposes: firstly, it coats the oxide nanoparticles to prevent the brittle oxides from detaching; secondly, the soft layer itself possesses excellent lubrication properties and bonds well with the substrate. The high hardness of the nano-oxides and the rolling effect generated during friction reduce the coefficient of friction. Combining oxide nanoparticles with the soft layer can effectively improve the wear resistance and service life of the coating.

[0009] A magnetron sputtering method for the above-mentioned wear-resistant nanocomposite coating includes the following steps:

[0010] S1. Sandblast the surface of the metal substrate to be sputtered, then ultrasonically clean and dry it;

[0011] S2. Place the metal substrate to be sputtered into the sputtering cavity using a fixture. At the same time, install a soft metal target with a soft layer and a Fe2O3 target with a support layer into the sputtering cavity. Adjust the distance between the target and the substrate and evacuate the sputtering cavity.

[0012] S3. Introduce argon gas into the cavity and adjust the gas pressure to perform high-pressure cleaning of the surface of the metal substrate to be sputtered.

[0013] S4. Start the sample disk rotation. The rotation speed of the sample disk is 10-30 r / min; perform wear-resistant nano-gradient composite coating sputtering on the metal substrate to be sputtered.

[0014] Preferably, in step S1, the surface roughness Ra of the metal substrate to be sputtered is 1–2.5 μm after sandblasting, and it is ultrasonically cleaned in an alcohol solution for 10–30 min; in step S2, the distance between the soft metal target and the surface of the metal substrate to be sputtered is 9–15 cm, and the distance between the Fe2O3 target and the surface of the metal substrate to be sputtered is 8–12 cm; the vacuum degree of the sputtering chamber is 5 × 10⁻⁶. -4 Pa ~ 5 × 10 -3 Pa.

[0015] Preferably, in step S3, the high-pressure cleaning voltage is 700V to 850V, the air pressure is 1 to 2.5Pa, and the time is 10 to 30 minutes.

[0016] Preferably, step S4 involves simultaneously performing soft metal target sputtering and Fe2O3 target sputtering; adjusting the DC power supply power of the soft metal target and the RF power supply power of the Fe2O3 target; opening the sample stage baffle, the soft metal target baffle, and the Fe2O3 target baffle; starting to deposit a soft layer formed by soft metal and a support layer formed by Fe2O3 on the metal substrate to be sputtered; gradually decreasing the DC power supply power of the soft metal target and gradually increasing the RF power supply power of the Fe2O3 target; after the coating is completed, turning off the DC power supply and the RF power supply, turning off the soft metal target baffle, the Fe2O3 target baffle, and the sample stage baffle, and removing the sample.

[0017] Preferably, the DC power supply power of the soft metal target is 10W to 50W, and the DC power supply power of the soft metal target gradually decreases uniformly from 50W; the RF power supply power of the Fe2O3 target is 160W to 200W, and the RF power supply power of the Fe2O3 target gradually increases uniformly from 160W; the deposition time is 2h.

[0018] Preferably, step S4 involves: starting the DC power supply, opening the sample stage baffle and the soft metal target baffle, depositing a soft layer of soft metal on the metal substrate to be sputtered, and after sputtering to a certain thickness, turning off the DC power supply and the soft metal target baffle; starting the RF power supply, depositing an Fe2O3 nanoparticle layer on the surface of the soft layer, and after sputtering to a certain thickness, turning off the RF power supply, the Fe2O3 target baffle, and the sample stage baffle, and removing the sample; and performing micro-motion wear on the sample.

[0019] Preferably, the thickness of the Fe2O3 nanoparticle layer is 1-4 μm, and the thickness of the soft layer is 2-6 μm; the DC power supply power of the soft metal target is 40-80 W, and the RF power supply power of the Fe2O3 target is 120-190 W.

[0020] Preferably, the load applied by the fretting wear is 10-600N.

[0021] There are two methods for preparing the coating: one is to use target co-sputtering technology, which causes the number of oxide nanoparticles to gradually decrease from the surface of the coating towards the center, while the number of soft layers gradually increases from the surface of the coating towards the center, forming a reverse composite gradient coating of the two types of materials. The other method is to prepare a soft layer on the substrate surface, with a composite gradient coating composed of nano-oxides on the surface of the soft layer.

[0022] The advantages and positive effects of the wear-resistant nanocomposite coating and its magnetron sputtering method described in this invention are as follows:

[0023] 1. The composite coating is prepared by magnetron sputtering technology, which is simple and easy to operate. It can precisely control the particle size and film thickness of soft metals and Fe2O3. Different particles are evenly distributed in the coating without obvious voids or other defects.

[0024] 2. The wear-resistant nanostructure gradient coating prepared by the present invention utilizes the extrusion and shearing effect of the load on the outer Fe2O3 layer during the fretting wear process to gradually enter the plastic soft metal layer, automatically constructing a soft metal and Fe2O3 nanocomposite gradient lubrication layer. The soft and hard metals work synergistically, resulting in excellent wear resistance.

[0025] 3. This invention, by controlling the multi-target magnetron sputtering process parameters, makes the sputtering efficiency of Fe2O3 and soft metal change in opposite directions with time and thickness, thus preparing a reverse composite gradient coating with different element contents. The mutual encapsulation of soft metal and Fe2O3 provides a certain load-bearing effect, improving the overall strength of the composite coating and preventing the soft metal from being worn away quickly. Fe2O3 reduces fretting wear of the material through rolling; while the soft metal mainly plays a role in encapsulation to prevent oxide shedding, thereby improving the service life of the coating.

[0026] 4. This invention utilizes magnetron sputtering technology to prepare a nanocomposite coating consisting of spherical oxide nanoparticles with rolling lubrication and a self-lubricating soft metal. The coating exhibits high adhesion to the substrate, and the particle size is controllable. Attached Figure Description

[0027] Figure 1 The morphology of Ag particles in the nanocomposite coating of the sample in Example 1 of this invention;

[0028] Figure 2 The particle morphology of Fe2O3 in the nanocomposite coating of the sample in Example 1 of this invention;

[0029] Figure 3 This is a scanning electron microscope (SEM) image of the longitudinal section of the nanocomposite coating of the sample in Example 1 of this invention;

[0030] Figure 4 This is the cross-sectional elemental energy spectrum of the nanocomposite coating of the sample in Example 1 of the present invention;

[0031] Figure 5 The surface particle morphology of the nanocomposite coating of the sample in Example 3 of this invention;

[0032] Figure 6 This is a scanning electron microscope (SEM) image of the longitudinal section of the nanocomposite coating of the sample in Example 3 of this invention;

[0033] Figure 7 This is the elemental energy spectrum of the longitudinal section of the nanocomposite coating of the sample in Example 3 of the present invention;

[0034] Figure 8 The graphs show the micro-friction coefficient curves of the nanocomposite coatings prepared in Examples 2 and 3.

[0035] Figure 9 The bar chart shows the wear depth and wear volume of the nanocomposite coatings prepared in Examples 2 and 3. Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] A wear-resistant nano-gradient composite coating is composed of oxide nanoparticles and a soft layer. During the friction process, the soft layer coats the outside of the oxide nanoparticles. The number of oxide nanoparticles gradually decreases from the surface of the coating towards the center, while the number of soft layers gradually increases from the surface of the coating towards the center.

[0038] The soft layer is a coating formed by one or two soft metals, such as Ag and Cu.

[0039] The oxide nanoparticles are Fe2O3 nanoparticles.

[0040] In the coating, Fe2O3 nanoparticles act as a solid lubricating layer, transforming sliding into rolling during fretting wear, thus significantly improving the fretting wear resistance of the metal substrate. The soft metal in the coating forms a coating and bonds to the hard Fe2O3 nanoparticles, protecting them from peeling off during service.

[0041] During the fretting wear process, the load compresses the Fe2O3 nanoparticles, causing them to gradually enter the soft layer and form a soft metal-Fe2O3 nanocomposite lubricating layer. This allows the soft metal to coat and bond the hard Fe2O3 nanoparticles, thus improving the service life of the coating.

[0042] By varying the sputtering power of Fe2O3 and soft metal, coatings with different elemental contents were prepared. The mutual encapsulation of soft metal and Fe2O3 provides a certain load-bearing capacity, improving the overall strength of the composite coating and preventing the soft metal from being rapidly worn away. Simultaneously, this reverse gradient increases with wear depth, with a higher volume fraction of Fe2O3, which acts as a load-bearing and lubricating agent, while the soft metal primarily serves to encapsulate and prevent Fe2O3 from detaching, thus extending the coating's lifespan.

[0043] The magnetron sputtering method for the above-mentioned wear-resistant nanogradient composite coating includes the following steps:

[0044] S1. Sandblast the surface of the metal substrate to be sputtered, then ultrasonically clean and dry it.

[0045] The surface roughness Ra of the metal substrate to be sputtered is 1–2.5 μm after sandblasting, preferably 1.5–2 μm. Ultrasonic cleaning in an alcohol solution is then performed for 10–30 min, preferably 15–20 min.

[0046] S2. Place the metal substrate to be sputtered into the sputtering cavity using a fixture. At the same time, install a soft metal target with a soft layer and a Fe2O3 target with a support layer into the sputtering cavity. Adjust the distance between the target and the substrate and evacuate the sputtering cavity.

[0047] The distance between the soft metal target and the surface of the metal substrate to be sputtered is 9–15 cm, and the distance between the Fe₂O₃ target and the surface of the metal substrate to be sputtered is 8–12 cm. The vacuum level of the sputtering chamber is 5 × 10⁻⁶. -4 Pa ~ 5 × 10 -3 Pa.

[0048] S3. Introduce argon gas into the cavity and adjust the gas pressure to perform high-pressure cleaning of the surface of the metal substrate to be sputtered.

[0049] The high-pressure cleaning voltage is 700V~850V, and the air pressure is 1~2.5Pa, preferably 1.5~2Pa. The time is 10~30min, preferably 15-20min.

[0050] S4. Start rotating the sample disk at a speed of 10–30 r / min, preferably 15–20 r / min. Sputter a wear-resistant nanogradient composite coating onto the metal substrate to be sputtered.

[0051] There are two methods for sputtering:

[0052] One method involves simultaneous sputtering with a soft metal target and an Fe2O3 target. The DC power supply to the soft metal target and the RF power supply to the Fe2O3 target are adjusted. The sample stage baffle, soft metal target baffle, and Fe2O3 target baffle are opened. Deposition of the soft metal layer and the Fe2O3 support layer on the substrate to be sputtered begins. The DC power supply to the soft metal target is gradually decreased, while the RF power supply to the Fe2O3 target is gradually increased. After the deposition is complete, the DC and RF power supplies are turned off, and the soft metal target baffle, Fe2O3 target baffle, and sample stage baffle are closed. The sample is then removed.

[0053] The DC power supply power for the soft metal target is 10W to 50W, and the DC power supply power for the soft metal target gradually decreases uniformly from 50W; the RF power supply power for the Fe2O3 target is 160W to 200W, and the RF power supply power for the Fe2O3 target gradually increases uniformly from 160W; the deposition time is 2h.

[0054] Another method involves first sputtering a soft layer, followed by sputtering an Fe2O3 nanoparticle layer. The DC power supply is turned on, and the sample stage baffle and soft metal target baffle are opened. A soft layer of soft metal is deposited on the metal substrate to be sputtered. After sputtering to a certain thickness, the DC power supply and soft metal target baffle are turned off. The RF power supply is then turned on, and an Fe2O3 nanoparticle layer is deposited on the surface of the soft layer. After sputtering to a certain thickness, the RF power supply, Fe2O3 target baffle, and sample stage baffle are turned off, and the sample is removed. The sample is then subjected to fretting abrasion.

[0055] The thickness of the Fe2O3 nanoparticle layer is 1-4 μm, preferably 2-3 μm.

[0056] The thickness of the soft layer is 2-6 μm, preferably 4-5 μm.

[0057] The DC power supply for the soft metal target is 40–80W, preferably 50W–60W. The RF power supply for the Fe2O3 target is 120–190W, preferably 150W–160W.

[0058] Example 1

[0059] After the surface roughness of the metal substrate to be sputtered is 1.5μm after sandblasting, it is immersed in anhydrous ethanol for ultrasonic cleaning for 15 minutes and then dried with a hair dryer for later use.

[0060] The metal substrate material to be sputtered is placed into the sputtering chamber using a fixture. An Ag target and an Fe₂O₃ target are then placed inside the sputtering chamber. The distance between the Ag and Fe₂O₃ targets and the surface of the metal substrate to be sputtered is adjusted to 9 cm. The chamber is then evacuated to a vacuum of 6 × 10⁻⁶. -4 Pa;

[0061] Argon gas was introduced into the cavity and the pressure was adjusted to 2 Pa. The surface of the metal substrate to be sputtered was then cleaned under high pressure at 700 V for 15 min. The high pressure cleaning was then turned off.

[0062] The sample disk was started to rotate at a constant speed of 15 r / min. After adjusting the DC power of the Ag target to 50 W, the Ag target baffle and the sample stage baffle were opened to begin depositing an Ag thin film coating on the metal substrate. After 1 hour of deposition, the DC power and the Ag target baffle were turned off. Then, the RF power of the Fe2O3 target was adjusted to 180 W, the Fe2O3 target baffle was opened, and the Fe2O3 thin film coating was deposited on the Ag thin film coating. After 2 hours of deposition, the RF power and the Fe2O3 target baffle were turned off, the power supply and equipment were shut down, and the sample was removed to obtain a nanostructured gradient coating.

[0063] The particle morphology of the prepared Ag and Fe2O3 is as follows: Figure 1 , Figure 2 As shown, Ag particles have a size between 100 nm and 250 nm. Fe2O3 particles are spherical with a size between 15 and 50 nm.

[0064] To facilitate sample characterization, a nickel protective layer was deposited on the composite coating of the sample. The scanning electron microscope image and elemental energy dispersive spectroscopy (EDS) spectrum of the sample's longitudinal section are shown below. Figure 3 , Figure 4 As shown, the thickness of the Ag coating is approximately 2.7 μm, and the thickness of the Fe2O3 coating is approximately 2 μm.

[0065] The coating sample was subjected to fretting wear test under a load of 600N to construct the Fe2O3-Ag nanocomposite coating.

[0066] Example 2

[0067] After the surface roughness of the metal substrate to be sputtered is 1.8 μm after sandblasting, it is immersed in anhydrous ethanol for ultrasonic cleaning for 15 min and then dried with a hair dryer for later use.

[0068] The metal substrate material to be sputtered is placed into the sputtering chamber using a fixture. An Ag target and an Fe₂O₃ target are then placed inside the sputtering chamber. The distance between the Ag and Fe₂O₃ targets and the surface of the metal substrate to be sputtered is adjusted to 10 cm, and the chamber is evacuated to a vacuum of 6 × 10⁻⁶. - 4 Pa;

[0069] Argon gas was introduced into the cavity and the pressure was adjusted to 1.8 Pa. The surface of the metal substrate to be sputtered was then subjected to high-pressure cleaning at 750 V for 20 min. The high-pressure cleaning was then turned off.

[0070] The sample disk was started to rotate at a constant speed of 15 r / min. After adjusting the DC power of the Ag target to 40 W, the Ag target baffle and the sample stage baffle were opened to begin depositing an Ag thin film coating on the metal substrate. After 1 h of deposition, the DC power and the Ag target baffle were turned off. Then, the RF power of the Fe2O3 target was adjusted to 120 W, the Fe2O3 target baffle was opened, and the Fe2O3 thin film coating was deposited on the Ag thin film coating. After 1.5 h of deposition, the RF power and the Fe2O3 target baffle were turned off, the power supply and equipment were shut off, and the sample was removed to obtain a nanostructured gradient coating.

[0071] The coating sample was subjected to fretting wear test under a load of 50N to construct the Fe2O3-Ag nanocomposite coating.

[0072] Example 3

[0073] After the surface roughness of the metal substrate to be sputtered is 1.5μm after sandblasting, it is immersed in anhydrous ethanol for ultrasonic cleaning for 15 minutes and then dried with a hair dryer for later use.

[0074] The metal substrate material to be sputtered is placed into the sputtering chamber using a fixture. Simultaneously, an Ag target and an Fe2O3 target are installed in the sputtering chamber. The distance between the Ag target and the surface of the metal substrate is adjusted to 11 cm, and the distance between the Fe2O3 target and the surface of the metal substrate is adjusted to 8 cm. The chamber is then evacuated to a vacuum of 6 × 10⁻⁶. -4 Pa;

[0075] Argon gas was introduced into the cavity and the pressure was adjusted to 1.5 Pa. The surface of the metal substrate to be sputtered was then cleaned under high pressure at 700 V for 15 min. The high pressure cleaning was then turned off.

[0076] The sample disk was started to rotate at a constant speed of 20 r / min. Ag target sputtering and Fe2O3 target sputtering were performed simultaneously on the metal substrate to be sputtered. The Fe2O3 target RF power was adjusted to 160 W and the Ag target DC power was adjusted to 50 W. The target baffle and sample stage baffle were then opened, and Fe2O3 thin film coating and Ag thin film coating were deposited on the metal substrate. During the coating deposition process, the Fe2O3 target RF power was gradually increased to 200 W and the Ag target DC power was decreased to 10 W to prepare coatings with different element contents. After 2 h of deposition, the Ag target and Fe2O3 target power was turned off, the target baffle was turned off, and the sample was taken out to obtain a nanocomposite gradient coating.

[0077] The surface particle morphology of the prepared Ag and Fe2O3 nanocomposite coating is as follows: Figure 5 As shown, the particle size of the composite coating is between 20-60 nm.

[0078] The longitudinal section scanning electron microscope (SEM) image and elemental energy spectrum of the prepared Ag / Fe₂O₃ nanocomposite coating are shown below. Figure 6 , Figure 7 As shown, the thickness of the composite coating is approximately 3.2 μm.

[0079] The nanocomposite coatings prepared in Example 2 and Example 3 were subjected to fretting wear experiments under a load of 50 N, and their wear performance was compared with that of the substrate. The measured results of the friction coefficient, wear depth, and wear volume are as follows: Figure 8 , Figure 9 As shown, the wear resistance of the two prepared coatings is not significantly different, but the wear resistance of the nanocomposite coating is significantly improved compared with the substrate. During the 30-minute wear performance measurement, the wear volume of the nanocomposite coating is approximately 1 / 2 that of the substrate. This indicates that the nanocomposite coating prepared by the method described in this invention can significantly improve the wear resistance of the substrate and significantly extend the service life of the coating.

[0080] Therefore, the present invention, by employing the above-mentioned wear-resistant nanocomposite coating and its magnetron sputtering method, can solve the problem that existing wear-resistant nanohard coatings are prone to peeling off, affecting the wear-resistant service life of the coating.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A wear resistant nanogradient composite coating, characterized by: The oxide nanoparticles and the soft layer are composed, the soft layer is coated outside the oxide nanoparticles during the friction process, the oxide nanoparticles gradually decrease from the surface to the center of the plating layer, and the soft layer gradually increases from the surface to the center of the plating layer. The soft layer is a plating layer formed by one or two soft metals of Ag and Cu, and the oxide nanoparticles are Fe2O3 nanoparticles.

2. The magnetron sputtering method for wear-resistant nanogradient composite coating according to claim 1, characterized in that, The method comprises the following steps: S1, sand blasting treatment is performed on the surface of the metal substrate to be sputtered, and then ultrasonic cleaning and drying are performed; S2, the metal substrate to be sputtered is placed into a sputtering cavity through a clamp, meanwhile, a soft metal target of the soft layer and an Fe2O3 target of the support layer are loaded into the sputtering cavity, the distance between the target material and the substrate is adjusted, and the sputtering cavity is vacuumized; S3, argon gas is introduced into the cavity and the gas pressure is adjusted, and the surface of the metal substrate to be sputtered is cleaned by high pressure; S4, the sample disc is rotated, and the rotation speed of the sample disc is 10-30 r / min; and the metal substrate to be sputtered is sputtered to form a wear-resistant nano gradient composite plating layer.

3. The magnetron sputtering method for wear-resistant nanometer gradient composite coating according to claim 2, characterized in that: In the S1, the surface of the metal substrate to be sputtered is sandblasted to have a roughness Ra of 1-2.5 μm, and is ultrasonically cleaned in an alcohol solution for 10-30 min; in the S2, the distance between the soft metal target and the surface of the metal substrate to be sputtered is 9-15 cm, and the distance between the Fe2O3 target and the surface of the metal substrate to be sputtered is 8-12 cm; the vacuum degree of the sputtering cavity is 5×10 -4 Pa-5×10 -3 Pa.

4. The magnetron sputtering method for wear-resistant nanometer gradient composite coating according to claim 2, characterized in that: In S3, the voltage of the high-pressure cleaning is 700V-850V, the gas pressure is 1-2.5Pa, and the time is 10-30min.

5. The magnetron sputtering method for wear-resistant nanogradient composite coating according to claim 2, characterized in that: In S4, the soft metal target sputtering and the Fe2O3 target sputtering are simultaneously performed; the power of the soft metal target direct current power supply and the power of the Fe2O3 target radio frequency power supply are adjusted; the sample stage baffle, the soft metal target material baffle and the Fe2O3 target material baffle are opened; the soft layer formed by the soft metal and the support layer formed by Fe2O3 are deposited on the metal substrate to be sputtered; the power of the soft metal target direct current power supply is gradually reduced, and the power of the Fe2O3 target radio frequency power supply is gradually increased; after the plating layer is completed, the direct current power supply and the radio frequency power supply are turned off, the soft metal target material baffle, the Fe2O3 target material baffle and the sample stage baffle are closed, and the sample is taken out.

6. The magnetron sputtering method for wear-resistant nanogradient composite coating according to claim 5, characterized in that: The power of the soft metal target direct current power supply is 10W-50W, and the power of the soft metal target direct current power supply is gradually and uniformly reduced from 50W; the power of the Fe2O3 target radio frequency power supply is 160-200W, and the power of the Fe2O3 target radio frequency power supply is gradually and uniformly increased from 160W; and the deposition time is 2h.

7. The magnetron sputtering method for wear-resistant nanometer gradient composite coating according to claim 2, characterized in that: In S4, the direct current power supply is started, the sample stage baffle and the soft metal target material baffle are opened, the soft layer formed by the soft metal is deposited on the metal substrate to be sputtered, the direct current power supply and the soft metal target material baffle are turned off after a certain thickness is sputtered, the radio frequency power supply is started, the Fe2O3 nanoparticle layer is deposited on the surface of the soft layer, the radio frequency power supply, the Fe2O3 target material baffle and the sample stage baffle are turned off after a certain thickness is sputtered, and the sample is taken out; and the sample is subjected to fretting wear.

8. The magnetron sputtering method for wear-resistant nanogradient composite coating according to claim 7, characterized in that: The thickness of the Fe2O3 nanoparticle layer is 1-4μm, the thickness of the soft layer is 2-6μm, the power of the soft metal target direct current power supply is 40-80W, and the power of the Fe2O3 target radio frequency power supply is 120-190W.

9. The magnetron sputtering method for wear-resistant nanogradient composite coating according to claim 7, characterized in that: The load applied by the fretting wear is 10-600N.

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