Self-lubricating anti-corrosion wear-resistant coating and preparation method thereof

Abstract

The invention relates to the technical field of surface treatment of mechanical parts, in particular to a self-lubricating anti-corrosion wear-resistant coating and a preparation method thereof.A transition layer is arranged between a coating substrate and a DLC layer, the transition layer contains Cr-O-W-C components, and a bottom layer, a middle layer and a surface layer are a crystal layer, a crystal-amorphous alternating layer and an amorphous layer respectively; the transition layer gradually relieves thermal / mechanical stress through collaborative optimization gradient design of components, structures and interlamellar spacing, the stripping resistance and corrosion resistance of the coating are remarkably improved, the service life of the coating is remarkably prolonged, collaborative improvement of corrosion resistance, wear resistance, self-lubricating performance and the like of the coating is further achieved, and the service life of the coating is prolonged. And finally, the double-gradient composite coating is constructed, so that the internal stress between the surface layer and the bottom layer can be relieved, long-acting corrosion prevention and a strong supporting effect on the diamond-like surface layer can be provided, the risk that the diamond-like surface layer falls off in the long-acting service process due to galvanic corrosion is relieved, the service life of parts is prolonged, and the equipment safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of surface treatment of mechanical parts, and particularly to a self-lubricating, anti-corrosion and wear-resistant coating and a preparation method thereof. Background Art

[0002] Currently, marine engineering materials (such as titanium alloys, low-carbon steels, stainless steels, etc.) still cannot fully meet the requirements of high precision, high reliability and long-life operation of key components of marine equipment. The integrated coating with self-lubricating, anti-corrosion and wear-resistant functions focuses on the surface properties of materials. Through various surface engineering technologies, the composition and structure of the material surface are redesigned and manufactured to endow the material surface with special lubrication, wear resistance and corrosion protection properties, which is the most effective and economical way to solve the problems of material friction, wear and corrosion.

[0003] In recent years, hard coatings prepared by thermal spraying technology, such as tungsten carbide-based cermets and oxide ceramic-based coatings, have been considered potential coatings for wear and corrosion resistance of moving / transmission mechanisms because of their simple preparation process, high hardness, bonding strength, density, wear resistance and corrosion resistance of the coatings, and their surfaces can still maintain the initial state after long-term service. However, the tungsten carbide coatings and oxide ceramic-based coatings prepared by thermal spraying are wear-resistant but not friction-reducing, which usually leads to increased wear of the friction pairs cooperating with the coatings and significantly reduced service life. Diamond-like carbon (DLC) films are a type of carbon thin films with diamond structure and graphite structure, and have excellent properties similar to diamond, especially excellent tribological properties and good chemical stability, which are particularly suitable for surface strengthening treatment of moving parts and have broad application prospects in fields such as key components and precision molds. However, due to the large difference in hardness between the commonly used metal substrates and the film layers, the film layers are thin and have defects such as high brittleness and internal stress. When the load is high, directly preparing DLC film layers on the substrates is likely to cause the film layers to peel off or collapse. In addition, when the DLC film layers are applied to the marine environment with high temperature, high humidity and high salt, the corrosive medium can easily reach the substrate through the film layer defects to cause corrosion, and then cause the film layers to rupture.

[0004] In summary, relying solely on single hard coatings and DLC film layers is difficult to independently and effectively meet the long-life and high-reliability requirements under the dynamic friction-wear-corrosion coupling damage of moving, transmission, connection and dynamic sealing components in harsh marine environments. Summary of the Invention

[0005] The purpose of the present invention is to provide a self-lubricating, anti-corrosion and wear-resistant coating and a preparation method thereof to solve the problem that existing hard coatings cannot meet the surface protection requirements of parts in marine environments.

[0006] An embodiment of the present invention provides a self-lubricating, anti-corrosion and wear-resistant coating, including: A coating substrate; Transition layer, the transition layer is disposed on the coating substrate, the transition layer contains Cr-O-W-C components, and successively includes a bottom layer, an intermediate layer, and a surface layer from near the coating substrate to away from the coating substrate. The bottom layer, the intermediate layer, and the surface layer are a crystal layer, a crystal amorphous alternating layer, and an amorphous layer respectively, and the thicknesses between the bottom layer, the intermediate layer, and the surface layer are all 50-200 nm; wherein, the content of Cr in the transition layer gradually decreases from the bottom layer to the surface layer, and the content of W in the transition layer gradually increases from the intermediate layer to the surface layer; DLC layer, the DLC layer is disposed on the surface layer of the transition layer; wherein, the bottom layer is a Cr2O3 layer, the intermediate layer is a Cr2O3-W-C composite layer, and the surface layer is a W-C composite layer.

[0007] Optionally, the coating substrate is a WC-Ni based hard alloy coating.

[0008] Optionally, the thickness of the bottom layer of the transition layer is 100-170 nm, the thickness of the intermediate layer is 50-120 nm, and the thickness of the surface layer is 50-140 nm.

[0009] In a second aspect, the present invention further provides a method for preparing a self-lubricating anti-corrosion wear-resistant coating for preparing the self-lubricating anti-corrosion wear-resistant coating as described in the first aspect, including: S100, after degreasing and defatting the substrate, perform sandblasting treatment on the spraying position; S200, prepare a coating substrate on the surface of the substrate; S300, grind and polish the coating substrate; S400, perform ion beam cleaning on the polished coating substrate; S500, deposit a transition layer on the coating substrate; S600, prepare a DLC layer on the transition layer.

[0010] Optionally, in S200, preparing a coating substrate on the surface of the substrate includes: On the surface of the substrate that has been sandblasted and preheated, use a supersonic flame spraying device for spraying, the carrier gas is 5-10 MPa, the oxygen flow rate is 850-1000 L / min, the kerosene flow rate is 20-30 L / h, the powder feeding rate is 50-130 g / min, the spraying distance is 130-180 mm, the spraying gun moving speed is 10-30 mm / s, and a WC-Ni based hard alloy coating is formed after spraying.

[0011] Optionally, in S300, grinding and polishing the coating substrate includes: Under the condition that the sample is at 400 - 800 rpm, polish it successively with diamond grinding discs of 300, 600, 1000, 1500 and 2000 meshes until the surface roughness of the coated substrate reaches Ra 0.1 - 0.3 μm; the thickness of the polished coated substrate is 50 - 200 μm.

[0012] Optionally, in S400, perform ion beam cleaning on the polished coated substrate, including: Clean for 40 - 80 min under the conditions that the pressure in the deposition furnace is 0.2 - 0.8 Pa, the argon flow rate is 150 - 300 sccm, the ion source is 1.0 - 2.5 kW, and the negative bias voltage is 100 - 600 V by using an ion beam.

[0013] Optionally, in S500, deposit a transition layer containing Cr - O - W - C components on the coated substrate, including: S510, pump the vacuum degree of the deposition furnace to 1 - 7×10 -3 Pa, then turn on the magnetron sputtering Cr target, with a power of 3 - 8 kW, an argon flow rate of 50 - 200 sccm, an oxygen flow rate of 1 - 1.5 sccm, and a time of 10 - 20 min, so as to form a Cr2O3 layer; S520, turn off the magnetron Cr target, oxygen, and argon, and pump the vacuum for 10 - 30 min; S530, turn on the magnetron Cr target and W target, with a power of 0.5 - 3 kW, adjust the relative sputtering amount of the Cr target and the W target, an argon flow rate of 100 - 300 sccm, and an acetylene flow rate of 1 - 5 sccm, and introduce a carbon source, so as to form a Cr2O3 - W - C composite layer; S540, turn off the Cr target, increase the power of the W target to 4 - 6 kW, an argon flow rate of 100 - 300 sccm, and slowly increase the acetylene flow rate to 10 - 80 sccm to increase the carbon content and form a W - C composite layer.

[0014] Optionally, in S600, prepare a DLC layer on the transition layer, including: Turn off the W target and argon, increase the acetylene flow rate to 100 - 200 sccm, a negative bias voltage of 200 - 900 V, for 30 - 60 min, to form a DLC layer with a high sp³ content.

[0015] The embodiments of the present invention have at least the following technical effects: The embodiments of the present invention provide a self-lubricating, anti-corrosion and wear-resistant coating. By setting a transition layer between the coating substrate and the DLC layer, the transition layer is designed with a synergistic optimization gradient through composition, structure and layer spacing to gradually relieve thermal / mechanical stress, significantly improve the spalling resistance, corrosion resistance and service life of the coating, further realize the synergistic improvement of the performance such as anti-corrosion, wear resistance and self-lubrication of the coating, and finally construct a double-gradient composite coating to relieve the internal stress between the surface layer and the bottom layer, which is beneficial to provide long-term anti-corrosion and strong support effect for the diamond-like carbon surface layer, thus reducing the risk of the diamond-like carbon surface layer falling off during long-term service due to galvanic corrosion, and further improving the service life of parts and the safety of equipment. Furthermore, using Ni-based alloys such as Ni / NiCr / NiMoCrFeCo as the binder phase of the WC-based coating or directly adopting an oxide ceramic-based coating can provide long-term anti-corrosion and strong support effect for the surface layer; through the double-gradient transition of composition and structure, the internal stress between the surface layer and the bottom layer can be relieved, which can ensure the long-term anti-corrosion, wear resistance and lubrication effects of the double-layer structure composite coating. At present, it has been applied to components such as the thrust disk of a water-lubricated bearing, coupling, bushing, and spherical plain bearing, realizing its wear-resistant, anti-corrosion and lubrication functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic diagram of the film structure of a self-lubricating, anti-corrosion and wear-resistant coating provided by the embodiments of the present invention; Figure 2 It is a schematic diagram of the electron microscope of the film of a self-lubricating, anti-corrosion and wear-resistant coating provided by the embodiments of the present invention; Figure 3 It is a schematic diagram of the electron microscope of the transition layer of a self-lubricating, anti-corrosion and wear-resistant coating provided by the embodiments of the present invention; Figure 4 It is a flowchart of the preparation method of a self-lubricating, anti-corrosion and wear-resistant coating provided by the embodiments of the present invention; Figure 5 It is a specific flowchart of step S500 in the preparation method of a self-lubricating, anti-corrosion and wear-resistant coating provided by the embodiments of the present invention; Figure 6 It is a schematic diagram of the salt spray test image data of the substrate coatings of WC-Co-Cr, WC-Cr3C2-Ni and WC-Co; Figure 7Schematic diagram of image data of salt spray test with WC-Ni and WC-NiCr alloy as the base coating; Figure 8 Schematic diagram for comparison of mechanical properties of AT3 coating and AT3-DLC coating; Figure 9 Schematic diagram for comparison of tribological properties of AT3 coating and AT3-DLC coating in atmospheric environment; Figure 10 Schematic diagram for comparison of tribological properties of AT3 coating and AT3-DLC coating in seawater environment; Figure 11 Schematic diagram for comparison of corrosion resistance of AT3 coating and AT3-DLC coating; Figure 12 Schematic diagram for comparison of mechanical properties of WC coating and WC-DLC coating; Figure 13 Schematic diagram for comparison of tribological properties of WC coating and WC-DLC coating in atmospheric environment; Figure 14 Schematic diagram for comparison of tribological properties of WC coating and WC-DLC coating in seawater environment.

[0018] Icon: 100 - coating base; 200 - transition layer; 210 - bottom layer; 220 - intermediate layer; 230 - surface layer; 300 - DLC layer. Detailed implementation manners

[0019] Next, the technical solutions of the present invention will be described clearly and completely in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] Those skilled in the art of the present technology can understand that unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of those of ordinary skill in the technical field to which the present invention belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless specifically defined as here.

[0021] Those skilled in the art can understand that, unless specifically stated otherwise, the singular forms "a", "an", "the" and "said" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present invention means the presence of the described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their groups. The phrase "and / or" used herein includes all or any unit and all combinations of one or more of the associated listed items.

[0022] Combined with Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a self-lubricating anti-corrosion and wear-resistant coating, including: a coating substrate 100, a transition layer 200 and a DLC layer 300 formed in sequence on the surface of a substrate. The substrate can be regarded as a mechanical component. By forming a self-lubricating anti-corrosion and wear-resistant coating on certain areas of the mechanical component in a specific environment, the effects of anti-corrosion and wear resistance can be achieved. Optionally, the coating substrate 100 can be a tungsten carbide-based cermet coating or an oxide ceramic-based coating, with a thickness of 50 - 200 μm.

[0023] Optionally, the coating substrate 100 is a WC-Ni-based cemented carbide coating or an oxide ceramic-based coating. The oxide ceramic-based coating can be selected from: chromium oxide, zirconium oxide, alumina, alumina-titanium oxide, chromium oxide-titanium oxide, etc. The preferred oxide ceramic material is alumina-3wt.% titanium oxide.

[0024] Specifically, the transition layer 200 is located between the coating substrate 100 and the DLC layer 300 to mitigate the property differences between the substrate and the main component material of the DLC layer 300, thereby improving the protective performance of the coating. Among them, the transition layer 200 contains Cr-O-W-C components. The transition layer 200 specifically includes a bottom layer 210, an intermediate layer 220 and a surface layer 230 arranged in sequence, and the bottom layer 210 is closer to the coating substrate 100 than the intermediate layer 220 and the surface layer 230. The bottom layer 210, the intermediate layer 220 and the surface layer 230 are crystal layer, crystal amorphous alternating layer and amorphous layer according to the crystal respectively. The interlayer thicknesses of the bottom layer 210, the intermediate layer 220 and the surface layer 230 are all 50 - 200 nm; among them, the content of Cr in the transition layer 200 gradually decreases from the bottom layer 210 to the surface layer 230, and the content of W in the transition layer 200 gradually increases from the intermediate layer 220 to the surface layer 230, thereby forming a composition gradient coating, improving the interfacial bonding characteristics between the coating substrate 100 and the DLC layer 300, and alleviating the peeling off during the long-term service of the coating due to galvanic corrosion.

[0025] Furthermore, through the multi-energy field composite regulation process, the transition layer 200 is divided into three main layers according to the structural gradient. The main basis for the subdivision between its layers is the crystal phase structure. From the bottom layer 210 to the surface layer 230 of the transition layer 200, they are the crystal layer (the first layer), the crystal-amorphous alternating layer (the second layer), and the amorphous layer (the third layer), as Figure 2 and 3 shown.

[0026] The crystal layer is a stripe-free layer. Optionally, the crystal layer is a Cr2O3 layer. The Cr2O3 layer is composed of columnar crystals. Columnar crystals refer to observing the structure of the crystal layer under a scanning electron microscope. Its crystallographic orientation is arranged along a certain direction, usually presenting a relatively regular columnar shape, and having a certain preferred orientation growth characteristic during the growth process. The longitudinal grain boundaries of the columnar crystals provide a preferential path for stress release. By grain boundary sliding or microcrack deflection, the risk of crack propagation perpendicular to the coating direction is reduced; the thermal expansion coefficient of the columnar crystal structure is closer to that of the metal or ceramic substrate, reducing the interfacial thermal mismatch stress.

[0027] The crystal-amorphous alternating layer is the second middle layer (coarse stripe layer). Having a similar coarse stripe shape means observing the crystal-amorphous alternating layer under a scanning electron microscope. Due to the overlap of different substances alternating, a coarse stripe-like morphology is formed; optionally, the crystal-amorphous alternating layer in this embodiment can be a Cr2O3-W-C composite layer. The large crystal region and the amorphous phase interface spacing allow more plastic deformation space. The strain energy is absorbed synergistically through the dislocation slip of the crystal phase and the viscoelastic deformation of the amorphous phase.

[0028] The amorphous layer is the third surface layer (fine stripe layer). Having a similar fine stripe shape means observing the amorphous layer under a scanning electron microscope, forming a fine stripe-like morphology; it can be understood that the fine stripe shape is relative to the coarse stripe shape, with an obvious distinction between the stripe thickness of the coarse stripe and the fine stripe. The stripe thickness of the coarse stripe is greater than that of the fine stripe. The uniformity of the amorphous structure and the small stripe spacing (no grain boundaries or dislocations) avoid local stress concentration points. The residual stress is dispersed through uniform deformation at the atomic scale; the atomic arrangement is short-range ordered and long-range disordered, and the isotropic characteristics make the stress distribution highly uniform, avoiding stress concentration at grain boundaries or phase boundaries. Optionally, the amorphous layer is a W-C composite layer. The carbon element in the W-C layer bonds with the sp³ bonds of the DLC film to form a strong chemical interface (because in the W-C composite layer, the carbon element combines with tungsten elements and other carbon atoms in a sp³ hybridized state. The carbon atoms in the DLC surface layer also mainly exist in a sp³ hybridized state. This same hybridized state enables the carbon element in the W-C layer to have good chemical bonding compatibility with the DLC film. When the W-C layer contacts the DLC film, the carbon atoms between them can be interconnected through sp³ bonding, thereby forming a strong chemical interface), reducing the interfacial stress caused by bonding mismatch. The high-density interface and amorphous uniformity of the fine stripes disperse the stress at the atomic scale, avoiding crack initiation, and providing a seamless chemical transition for the DLC layer 300. As the outermost transition layer 200, it is necessary to balance the uniform stress distribution and the interfacial compatibility with the DLC layer 300, reducing the interfacial defects caused by sudden changes in chemical composition.

[0029] Through the collaborative optimization of composition, structure, and layer spacing, the dual-gradient design of the embodiments of the present invention gradually alleviates thermal / mechanical stress, significantly improves the spalling resistance, corrosion resistance, and service life of the coating, further realizes the collaborative improvement of properties such as anti-corrosion, wear resistance, and self-lubrication of the coating. Finally, constructing a dual-gradient composite coating can relieve the internal stress between the surface layer and the bottom layer 210, which is beneficial for providing long-term anti-corrosion and a strong support effect on the diamond-like carbon surface layer, thereby reducing the risk of the diamond-like carbon surface layer peeling off during long-term service due to galvanic corrosion, and further improving the service life of components and the safety of equipment.

[0030] Optionally, the thickness of the bottom layer of the transition layer is 100 - 170 nm, the thickness of the intermediate layer is 50 - 120 nm, and the thickness of the surface layer is 50 - 140 nm. The advantages of such thickness settings are as follows: Bottom layer Cr2O3 layer (100 - 170 nm): There are differences in the thermal expansion coefficients between the thermal sprayed oxide ceramic-based coating, WC-based hard coating, and the Cr2O3 layer. A thicker Cr2O3 bottom layer can better adapt to this difference, reduce the tensile stress generated at the interface due to thermal expansion mismatch, just like a "cushion", reducing the risk of the coating cracking due to stress concentration, and ensuring that the subsequent coating does not easily peel off. Intermediate layer Cr2O3-W-C layer (50 - 120 nm): This layer is relatively thin. While ensuring a certain buffering effect, its composition gradually decreases in Cr2O3 content and gradually increases in W and C content. This gradual change in composition enables the physical and chemical properties of the coating to transition smoothly, avoiding excessive internal stress generated due to sudden changes in properties within the coating. To a certain extent, it balances the performance differences between the bottom layer and the surface layer, making the stress distribution more uniform. In addition, through the gradual change in composition, the bonding between the intermediate layer and the bottom layer and the surface layer is closer. The chemical bonding and physical interlocking effects between Cr2O3, W, and C work together synergistically, avoiding the decrease in bonding force caused by sudden changes in composition, and enhancing the integrity and stability of the coating. The W-C layer (50 - 140 nm) has high hardness and strength and can withstand high loads and frictional forces. Its thickness is moderate. While maintaining good wear resistance, it reduces stress concentration caused by sudden changes in hardness. As the surface layer in contact with the DLC film, it can effectively disperse stress to the intermediate layer and the bottom layer, further optimizing the stress state of the entire coating system.

[0031] Based on the same inventive concept, as Figure 4 shown, an embodiment of the present invention further provides a method for preparing a self-lubricating, anti-corrosion, and wear-resistant coating, including: S100, after degreasing and defatting the substrate, perform sandblasting on the spraying position.

[0032] Specifically, sandblasting can remove the oxide layer on the substrate surface to increase surface activity and improve the bonding strength between the coating and the substrate. The abrasive material used for sandblasting can be white fused alumina, brown fused alumina, or zirconium corundum, and the particle size of the abrasive material can be 46#, 54#, or 60#. During sandblasting, the sandblasting pressure can be controlled at 0.2 - 0.5 MPa, and the sandblasting distance can be controlled within 100 - 300 mm. The axial direction of the nozzle of the sandblasting machine forms an angle of 70° - 90° with the sample surface. After sandblasting, the surface roughness of the specimen is uniform and there is no metallic luster, and the residual sand grains or dust can be blown off with compressed air.

[0033] S200, prepare a coating substrate 100 on the substrate surface.

[0034] Optionally, on the surface of the substrate that has been sandblasted and preheated, spraying is carried out using an atmospheric plasma spraying device, with the plasma gun current being 450 A to 650 A, the argon gas flow rate being 30 L / min to 45 L / min, the hydrogen gas flow rate being 4 L / min to 10 L / min, the spraying distance being 100 mm to 150 mm, the powder feeding rate being 5 g / min to 25 g / min, and an oxide ceramic-based coating being formed after spraying.

[0035] Optionally, on the surface of the substrate that has been sandblasted and preheated, spraying is carried out using a supersonic flame spraying device, with the carrier gas being 5 to 10 MPa, the oxygen gas flow rate being 850 to 1000 L / min, the kerosene flow rate being 20 to 30 L / h, the powder feeding rate being 50 to 130 g / min, the spraying distance being 130 to 180 mm, the gun moving speed being 10 to 30 mm / s, and a WC-Ni-based cemented carbide coating being formed after spraying.

[0036] S300, grinding and polishing the coating substrate 100.

[0037] Specifically, under the condition that the sample is at 400 to 800 rpm, grinding and polishing are successively carried out using diamond grinding discs with 300, 600, 1000, 1500, and 2000 meshes until the surface roughness of the coating substrate 100 reaches Ra 0.1 to 0.3 μm; the thickness of the polished coating substrate 100 is 50 to 200 μm.

[0038] In this embodiment, by controlling the surface roughness Ra of the coating substrate 100 within the range of 0.1 to 0.3 μm, it is beneficial to achieve a balance among mechanical interlocking, chemical bonding, and stress buffering, thereby improving the bonding effect between the film layers. If the roughness is too high (Ra > 0.3 μm), sharp protrusions or deep grooves will cause local stress concentration in the DL layer, easily triggering cracks or peeling; while being too smooth (Ra < 0.1 μm) lacks anchor points, resulting in insufficient bonding force, and this range (0.1 to 0.3 μm) exactly balances the two, ensuring uniform stress distribution.

[0039] S400, ion beam cleaning the polished coating substrate 100.

[0040] Specifically, ion beam cleaning is carried out for 40 to 80 min under the conditions that the pressure in the deposition furnace is 0.2 to 0.8 Pa, the argon gas flow rate is 150 to 300 sccm, the ion source is 1.0 to 2.5 kW, and the negative bias voltage is 100 to 600 V.

[0041] S500, depositing a transition layer 200 on the coating substrate 100.

[0042] Optionally, as Figure 5As shown, the specific process of depositing the transition layer 200 in S500 includes the following steps S510 to S540: S510, evacuate the deposition furnace to a vacuum of 1 to 7×10 -3 Pa, then turn on the magnetron sputtering Cr target, with a power of 3 to 8 kW, an argon flow rate of 50 to 200 sccm, and an oxygen flow rate of 1 to 1.5 sccm (if the oxygen flow rate is too low, metal Cr residues will occur; if the oxygen flow rate is too high, unstable CrO3 may be formed), for a time of 10 to 20 min, thus forming a Cr2O3 layer.

[0043] In this embodiment, high-power magnetron sputtering is adopted, which is beneficial to improving the sputtering rate of the Cr target, increasing the energy of deposited particles, enhancing the migration ability of high-energy Cr atoms on the substrate surface, preferentially growing along specific crystal orientations, forming a columnar crystal structure, and improving the film layer density.

[0044] S520, turn off the magnetron Cr target, oxygen, and argon, and evacuate for 10 to 30 min.

[0045] S530, turn on the magnetron Cr target and W target, with a power of 0.5 to 3 kW, and adjust the relative sputtering amount of the Cr target and W target, thus forming a Cr2O3-W-C composite layer.

[0046] In this embodiment, at low power (0.5 to 3 kW), the co-sputtering rate of Cr and W is relatively low, the atomic mixing is more uniform, forming a coarse stripe crystal and amorphous carbon doped structure. The Cr2O3 crystal is partially replaced by W and C, forming grains surrounded by an amorphous carbon network. The argon flow rate is 100 to 300 sccm, and the acetylene flow rate is 1 to 5 sccm. A carbon source is introduced to react with the sputtered W to form carbides. The incorporation of carbon destroys the long-range order and forms an amorphous phase. At the same time, the metallic bond of W and the covalent bond of C are combined to enhance the interlayer toughness, and finally a Cr2O3-W-C composite layer is formed. The entire deposition time is 5 to 40 min.

[0047] S540, turn off the Cr target, increase the power of the W target to 4 to 6 kW, the argon flow rate is 100 to 300 sccm, and the acetylene flow rate is slowly increased to 10 to 80 sccm to increase the carbon content and form a W-C composite layer.

[0048] In this embodiment, by increasing the sputtering power of the W target to dominate the deposition process, the kinetic energy of W atoms increases at high power, forming fine grains. By increasing the carbon content, a W-C composite phase is formed, forming an amorphous structure. The negative bias voltage is 50 to 150 V. At the same time, high-energy bombardment inhibits grain growth and promotes a fine stripe amorphous structure. The entire deposition time is 10 to 60 min.

[0049] It can be understood that the bottom layer 210, i.e., the Cr2O3 layer, can be obtained in step S510; this layer can form certain chemical connections or physical occlusions with components such as WC, providing a stable foundation for the subsequent attachment of the transition layer 200 and the DLC layer 300. In addition, Cr2O3 has good chemical stability and oxidation resistance, which can prevent the oxide ceramic coating or WC-based coating of the bottom layer 210 from being oxidized or reacting with substances in the surrounding environment, playing an isolation and protection role. Step S530 can obtain the intermediate layer 220, i.e., the alternating layer of Cr2O3-W-C; this layer gradually reduces the Cr2O3 content and increases the W content, alleviating the performance mutation between Cr2O3 and W, realizing the composition and structure transition from mainly Cr2O3 to mainly W, and enhancing the connection stability between layers. The ductility of W combined with the brittleness of Cr2O3 absorbs the interface stress and prevents crack propagation. The carbon element gradually increases from this layer, providing a pre-transition of the carbon-containing environment for the formation of the subsequent DLC layer 300, making the distribution of carbon elements in the coating system more reasonable, and contributing to the formation and stability of the carbon structure in the DLC layer 300. Step S540 obtains the surface layer 230, i.e., the alternating layer of W and C; the high W content in this layer forms tungsten carbide with C, combines with the sp³ / sp² carbon bonds of DLC, and reduces interface defects.

[0050] S600, preparing a DLC layer 300 on the transition layer 200.

[0051] Specifically, turn off the W target and argon, increase the acetylene flow rate to 100 - 200 sccm, the negative bias voltage is 200 - 900 V, for 30 - 60 min, to form a DLC layer 300 with a high sp³ content.

[0052] In this embodiment, a carbon-rich environment is provided by a high acetylene flow rate, and the negative bias voltage enhances the ion bombardment energy to break the ordered arrangement of carbon chains, forming an amorphous DLC film layer with a high sp³ content (diamond-like). At the same time, the high bias voltage densifies the film layer and reduces pores. As the final functional layer, the DLC layer 300 provides surface protection for the coating system through ultra-low friction, high hardness, and chemical inertness.

[0053] In the embodiment of the present invention, the gradient transition of the composition is achieved by adjusting the power and the flow rate of the introduced gas, and the gradient of the structure is achieved by depositing different layers facing different targets during the rotation of the sample fixed on the turntable.

[0054] In the embodiment of the present invention, the NiCr alloy is used as the bonding phase of the WC-based coating or directly uses an oxide ceramic coating, which can provide long-term anti-corrosion and strong support for the surface layer; through the double-gradient transition of the composition and structure, the internal stress between the surface layer and the bottom layer 210 can be alleviated, ensuring the long-term anti-corrosion, wear resistance, and lubrication effects of the double-layer structure composite coating. Currently, it has been applied to components such as the thrust disk of a water-lubricated bearing, coupling, shaft sleeve, and spherical plain bearing, realizing its wear-resistant, anti-corrosion, and lubrication functions.

[0055] In the embodiments of the present invention, the corrosion resistance of WC-based coatings with four different binder phases, namely Co, NiMoCrFeCo, NiCrCoMo, and NiCrMo, was studied and compared. The research results found that WC-Ni-based alloys have the best anti-corrosion performance. During the preliminary exploratory research process, the applicant prepared WC-based hard alloy coatings with different binder phases such as WC-Ni, WC-Co-Cr, WC-Cr3C2-Ni, WC-NiCr alloy, and WC-Co by using the HVOF technology, and evaluated the anti-corrosion performance of the coatings through electrochemical analysis and salt spray tests. The results further confirmed that the WC-Ni-based alloy coatings have excellent anti-corrosion performance (since the oxide coatings themselves have extremely excellent anti-corrosion performance, they are not within the scope of verification).

[0056] Furthermore, the applicant prepared DLC film layers on the surfaces of five materials, namely WC-Ni, WC-Co-Cr, WC-Cr3C2-Ni, WC-NiCr alloy, and WC-Co, among which Figure 6 are the salt spray test image data of WC-Co-Cr, WC-Cr3C2-Ni, and WC-Co as the substrate coatings ( Figure 6 in (a) shows the image of the WC-Co-Cr substrate coating before the salt spray test, Figure 6 in (b) shows the image of the WC-Co-Cr substrate coating after 1155 h of salt spray test, Figure 6 in (c) shows the image of the WC-Cr3C2-Ni substrate coating before the salt spray test, Figure 6 in (d) shows the image of the WC-Cr3C2-Ni substrate coating after 120 h of salt spray test, Figure 6 in (e) shows the image of the WC-Co substrate coating before the salt spray test, Figure 6 in (f) shows the image of the WC-Co substrate coating after 150 h of salt spray test), Figure 7 are the salt spray test image data of WC-Ni and WC-NiCr alloy as the substrate coatings ( Figure 7 in (a) shows the image of the WC-Ni alloy substrate coating before the salt spray test, Figure 7 in (b) shows the image of the WC-Ni alloy substrate coating after 2470 h of salt spray test, Figure 7 in (c) shows the image of the WC-NiCr alloy substrate coating before the salt spray test, Figure 7 in (d) shows the image of the WC-NiCr alloy substrate coating after 2470 h of salt spray test). The salt spray results show that there is a phenomenon of DLC film layer peeling off in the coatings with WC-Co-Cr, WC-Cr3C2-Ni, and WC-Co as the bottom layer 210.

[0057] The applicant prepared a DLC layer 300 on the surface of alumina-3wt.% titanium oxide ceramic coating (hereinafter referred to as AT3 coating) for comparison. The specific performance parameter comparison is referred to Figures 8 - 11 , where Figure 8 shows the comparison of the mechanical properties of AT3 (alumina-3%Wt. titanium oxide) coating and AT3-DLC coating. The results show that under the same maximum normal load, the hardness and elastic modulus of AT3-DLC coating are higher than those of AT3 coating, and the hardness is increased by 107.72%. The hardness and elastic modulus of the coating contribute to improving wear resistance. The H³ / E² value (defined as the ability to resist plastic deformation) indicates that as this value increases, the ability to resist plastic deformation becomes stronger. Figure 8 (c) in

[0058] Figure 9 shows the tribological property comparison of AT3 coating and AT3-DLC coating in the atmospheric environment, while Figure 10 shows the tribological property comparison of AT3 coating and AT3-DLC coating in the seawater environment. Figure 9 and Figure 10 The results shown indicate that whether in the atmospheric environment or the seawater environment, the AT3-DLC coating has a lower friction coefficient and a lower wear rate compared with the AT3 coating.

[0059] Figure 11 shows the corrosion resistance comparison of AT3 coating and AT3-DLC coating. The results show that the polarization resistance (Rp) of AT3-DLC coating reaches 4.178×10 6 Ω·cm², which is two orders of magnitude higher than that of AT3 coating. In addition, the corrosion current density of AT3-DLC coating is only 7.7441×10⁻ 9 A / cm², showing its excellent corrosion resistance compared with AT3 coating.

[0060] And by preparing a DLC layer 300 on the surface of WC-NiCr alloy coating for comparison. The specific performance parameter comparison is referred to Figures 12 - 14 , Figure 12 shows the comparison of the mechanical properties of WC coating and WC-DLC coating. The results show that the hardness of WC-DLC coating is higher than that of WC coating. The hardness of the coating helps to improve wear resistance. The H³ / E² value (defined as the ability to resist plastic deformation) indicates that as this value increases, the ability to resist plastic deformation becomes stronger. Figure 12 (c) in

[0061] Figure 13 shows the tribological property comparison of WC coating and WC-DLC coating in the atmospheric environment.Figure 14 For the comparison of the tribological properties of WC coatings and WC-DLC coatings in a seawater environment, Figure 13 and Figure 14 The results shown schematically indicate that the WC-DLC coating has a lower friction coefficient and a lower wear rate compared to the WC coating, whether in an atmospheric environment or a seawater environment.

[0062] Based on Figures 8 - 14 the comparative data, in the embodiments of the present invention, a DLC film is deposited on the surfaces of thermally sprayed oxide ceramic coatings and WC-based hard coatings, and a double-gradient transition layer in terms of composition and structure is designed, significantly improving the mechanical, tribological and corrosion resistance properties of the coatings. Compared with the original coatings, the DLC-coated composite coatings not only achieve breakthroughs in single properties, but also exhibit excellent comprehensive properties under various complex working conditions and environments. This fully demonstrates that the DLC coatings in the solutions of the present invention can form a good composite structure with different substrate coatings, play a synergistic role, and optimize the comprehensive properties of the coatings. It provides a more reliable technical solution for the application of coating materials in fields such as mechanical manufacturing and ocean engineering, and has significant innovation and practical value.

[0063] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0064] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "plurality" is two or more.

[0065] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. In the description of this specification, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A self-lubricating, anti-corrosion and wear-resistant coating, characterized in that: include: Coating substrate; A transition layer, wherein the transition layer is disposed on the coating substrate, the transition layer contains a Cr-OWC component, and includes a bottom layer, an intermediate layer, and a surface layer in a direction from close to the coating substrate to away from the coating substrate, wherein the bottom layer, the intermediate layer, and the surface layer are respectively a crystal layer composed of columnar crystals, a crystal-amorphous alternating layer with coarse stripes, and an amorphous layer with fine stripes, and the interlayer thickness of the bottom layer, the intermediate layer, and the surface layer is 50 to 200 nm; wherein the content of Cr in the transition layer gradually decreases from the bottom layer to the surface layer, and the content of W in the transition layer gradually increases from the intermediate layer to the surface layer; A DLC layer, the DLC layer is arranged on the surface of the transition layer; Among them, the bottom layer is a Cr2O3 layer, the middle layer is a Cr2O3-WC composite layer, and the surface layer is a WC composite layer.

2. The self-lubricating, anti-corrosion and wear-resistant coating according to claim 1, characterized in that: The coating substrate is a WC-Ni based hard alloy coating or an oxide ceramic based coating.

3. The self-lubricating, anti-corrosion and wear-resistant coating according to claim 1, characterized in that: The thickness of the bottom layer of the transition layer is 100-170 nm, the thickness of the middle layer is 50-120 nm, and the thickness of the surface layer is 50-140 nm.

4. A method for preparing a self-lubricating, anti-corrosion and wear-resistant coating, for preparing the self-lubricating, anti-corrosion and wear-resistant coating as claimed in any one of claims 1 to 3, characterized in that: The preparation method comprises: S100, after degreasing and removing oil from the substrate, the spraying position is sandblasted; S200, preparing a coating substrate on the surface of the substrate; S300, grinding and polishing the coating substrate; S400, performing ion beam cleaning on the polished coating substrate; S500, depositing a transition layer on the coating substrate; S600, preparing a DLC layer on the transition layer.

5. The method for preparing the self-lubricating, anti-corrosion and wear-resistant coating according to claim 4, characterized in that: In S200, a coating substrate is prepared on the surface of a substrate, including: The surface of the substrate that has been sandblasted and preheated is sprayed using atmospheric plasma spraying equipment, with a plasma spray gun current of 450 A to 650 A, an argon flow rate of 30 L / min to 45 L / min, a hydrogen flow rate of 4 L / min to 10 L / min, a spraying distance of 100 mm to 150 mm, and a powder feeding rate of 5 g / min to 25 g / min, to form an oxide ceramic-based coating after spraying.

6. The method for preparing the self-lubricating, anti-corrosion and wear-resistant coating according to claim 4, characterized in that: In S200, a coating substrate is prepared on the surface of a substrate, including: The surface of the substrate that has been sandblasted and preheated is sprayed using a supersonic flame spraying device, with a carrier gas of 5 to 10 MPa, an oxygen flow rate of 850 to 1000 L / min, a kerosene flow rate of 20 to 30 L / h, a powder feeding rate of 50 to 130 g / min, a spray distance of 130 to 180 mm, and a spray gun moving speed of 10 to 30 mm / s, to form a WC-Ni-based cemented carbide coating after spraying.

7. The method for preparing the self-lubricating, anti-corrosion and wear-resistant coating according to claim 4, characterized in that: In S300, the coating substrate is ground and polished, including: Under the condition of 400-800 rpm, the sample is ground and polished with 300, 600, 1000, 1500 and 2000 mesh diamond grinding discs in sequence until the surface roughness of the coating substrate reaches Ra 0.1-0.3 μm; the thickness of the coating substrate after grinding and polishing is 50-200 μm.

8. The method for preparing the self-lubricating, anti-corrosion and wear-resistant coating according to claim 4, characterized in that: In S400, the polished coating substrate is ion beam cleaned, including: The cleaning is carried out for 40 to 80 minutes by using an ion beam under the conditions of a pressure of 0.2 to 0.8 Pa in a deposition furnace, an argon gas flow rate of 150 to 300 sccm, an ion source of 1.0 to 2.5 kW, and a negative bias voltage of 100 to 600 V.

9. The method for preparing the self-lubricating, anti-corrosion and wear-resistant coating according to claim 4, characterized in that: In S500, a transition layer containing Cr-OWC components is deposited on the coating substrate, including: S510: Pump the vacuum of the deposition furnace to 1~7×10 -3 After Pa, magnetron sputtering of Cr target was started, with power of 3-8 kW, argon flow rate of 50-200 sccm, oxygen flow rate of 1-1.5 sccm, and time of 10-20 min, thereby forming a Cr2O3 layer; S520, turn off the magnetron Cr target, oxygen, and argon, and evacuate for 10-30 min; S530, start the magnetron Cr target and W target, the power is 0.5~3kw, adjust the relative sputtering amount of the Cr target and the W target, the argon flow rate is 100~300sccm, the acetylene flow rate is 1~5sccm, and introduce a carbon source to form a Cr2O3-WC composite layer; S540, turn off the Cr target, increase the W target power to 4~6kW, the argon flow rate to 100~300sccm, and slowly increase the acetylene flow rate to 10~80sccm to increase the carbon content and form a WC composite layer.

10. The method for preparing the self-lubricating, anti-corrosion and wear-resistant coating according to claim 4, characterized in that: In S600, a DLC layer is prepared on the transition layer, including: Turn off the W target and argon gas, increase the acetylene flow rate to 100~200 sccm, and negative bias 200~900 V for 30~60 min to form a DLC layer with a high sp³ content.

Images