Metal substrate surface antibacterial antifriction composite coating and preparation method thereof

Abstract

The invention relates to a metal substrate surface antibacterial antifriction composite coating and a preparation method thereof, and belongs to the technical field of vacuum deposition. A layered structure of a vanadium metal base layer, a gradient transition layer and a vanadium-silver-carbon composite layer is constructed on the surface of a metal matrix through a multi-arc ion plating process. Through gradient transition, the interface stress is reduced, the middle layer provides antibacterial ion reserve, the top layer slowly releases bacteria, amorphous carbon lubrication and ceramic phase bearing are combined, cooperation of high bonding strength, low frictional wear and long-acting bacteria resistance is achieved, the problem that friction reduction, wear resistance and long-acting bacteria resistance of a traditional coating are difficult to achieve at the same time is solved, and the coating is suitable for surface protection of medical surgical instruments.

Description

Technical Field

[0001] This invention relates to an antibacterial and friction-reducing composite coating for a metal substrate and its preparation method, belonging to the field of vacuum deposition technology. Background Technology

[0002] In medical device applications, physical vapor deposition of metal carbides / nitrides and carbon-based coatings is widely used on the surfaces of instruments such as scalpels, bone forceps, and bone saws due to their ultra-thin (micron- and submicron-level), high hardness (approximately 1500-3000 HV), good biocompatibility, and wear / corrosion resistance. This reduces friction, extends service life, and ensures long-term stability and safety. To address the risk of hospital-acquired infections, the antibacterial properties of silver have attracted attention, particularly through the release of Ag. + Interfering with bacterial metabolism and membrane structure to achieve broad-spectrum antibacterial activity, and the appropriate incorporation of hard coatings is considered a feasible strategy that balances antibacterial properties and durability.

[0003] To simultaneously achieve low friction and antibacterial functions, Ag-containing nitride or carbide composite layers are constructed on the surface of metal instruments. Existing silver-containing hard coatings are mostly formed using processes such as ion plating and sputtering. For example, Chinese invention patent CN112126900B discloses a high-temperature, low-friction, hard nano-multilayer VAlCN / VN-Ag coating. This coating is formed by alternating layers of multiple VAlCN barrier layers and multiple VN-Ag composite layers, with the alternation frequency ranging from 5 to 30 times. The VAlCN layer contains sp... 2 The coating comprises a graphite-like structure composed of hybrid carbon. The preparation method includes: activating the substrate surface; placing the activated substrate in a coating apparatus, selecting a V-target, an Ag-target, and an Al-target as cathodes, and introducing nitrogen and acetylene gases during the deposition process after selecting parameters. By controlling the Ag and Al target currents, the flow rates of nitrogen and acetylene gases, and the deposition time, a VAlCN barrier layer and a VN-Ag composite layer are alternately deposited on the substrate surface using multi-arc ion plating technology to form the coating. This composite coating system exhibits significant high-temperature and low-friction advantages, making it suitable for aerospace, metallurgy, automotive, foil bearing, and other fields.

[0004] Nitride coatings containing Ag and Cu antibacterial components are deposited on the surface of medical metal devices through ion plating and sputtering. However, these coatings have the following problems: first, existing hard coatings fail to effectively combine long-lasting antibacterial properties with friction reduction; second, insufficient bonding between the hard coating and the metal substrate leads to the risk of detachment, which can result in serious adverse conditions such as coating fragment residue, thrombosis, and tissue necrosis. Therefore, when applying these processes to medical applications, a more refined structural and kinetic match needs to be achieved between strong bonding, low friction, and stable antibacterial release to ensure both the reliability of the device during service and its long-term antibacterial effectiveness. Summary of the Invention

[0005] The present invention aims to solve the above problems by providing a composite coating for antibacterial and friction-reducing properties on the surface of a metal substrate.

[0006] The technical solution of the present invention to solve the above problems is as follows:

[0007] An antibacterial and friction-reducing composite coating for a metal substrate is formed on the surface of the metal substrate by a multi-arc ion plating process, and includes, in sequence away from the surface of the metal substrate, a vanadium metal underlayer, a gradient transition layer and a vanadium-silver-carbon composite layer.

[0008] The gradient transition layer comprises a vanadium metal phase and a vanadium carbide ceramic phase, wherein the vanadium carbide content increases from 0 to not less than 80 at.% along the direction away from the metal substrate.

[0009] The vanadium-silver-carbon composite layer comprises a silver metallic phase, a carbide ceramic phase, and an amorphous carbon phase, including an intermediate layer with a silver content of 3~20 at.% and a top layer with a silver content of 0.5~3 at.%.

[0010] In the above-mentioned technical solution of the present invention, performance synergy is achieved through a layered structural design. The bottom layer uses pure vanadium metal, which has a similar coefficient of thermal expansion and interfacial affinity to common metal substrates (such as stainless steel and titanium alloys), effectively reducing thermal stress and interfacial energy between the coating and the substrate, and improving initial bonding strength. The gradient transition layer transitions continuously from vanadium metal to the vanadium carbide ceramic phase (vanadium carbide content gradually increases from 0 to ≥80 at.%), avoiding abrupt changes in interfacial stress caused by direct contact between the metal and ceramic phases, reducing residual stress and crack initiation risk within the coating. Simultaneously, the high hardness and chemical stability of vanadium carbide provide a foundation for subsequent composite layers. The vanadium-silver-carbon composite layer further refines the function. The middle layer maintains a high silver content (3~20 at.%), serving as a "reservoir" for antibacterial active ingredients, ensuring sufficient silver ion release for efficient antibacterial effects. The top layer reduces the silver content to 0.5~3 at.%, reducing excessive exposure and burst release risk of surface silver, while combining with amorphous carbon (sp... 2 The self-lubricating properties of the primary phase and the wear-resistant and load-bearing capacity of the carbide ceramic phase ensure continuous antibacterial activity while reducing the coefficient of friction and improving wear resistance. Through compositional gradients and functional complementarity, each layer ultimately achieves a synergistic effect of high bonding strength, low friction and wear, and long-lasting antibacterial properties.

[0011] As a preferred embodiment of the above technical solution, the thickness of the gradient transition layer is 1 to 3 times that of the vanadium metal underlayer; the thickness of the vanadium metal underlayer is 0.1 to 1 μm.

[0012] The thickness of the underlayer is controlled at 0.1~1 μm, which ensures sufficient bonding with the substrate (too thin a layer can lead to insufficient bonding, while too thick a layer increases the process cost and may introduce greater residual stress), and forms a uniform metal transition layer through short-time deposition. The thickness of the gradient transition layer is 1~3 times that of the underlayer. This range can achieve a sufficient compositional gradient transition from vanadium to vanadium carbide (avoiding abrupt interface changes), and will not reduce the functionality of the overall coating due to excessive thickness of the transition layer. At the same time, the thickness ratio of 1~3 times ensures the stress buffering effect in the gradient region and the bonding reliability of the subsequent composite layer.

[0013] As a preferred embodiment of the above technical solution, the thickness of the vanadium-silver-carbon composite layer is 2~10 μm; wherein, the thickness of the top layer is less than 500 nm.

[0014] The total thickness of the composite layer (2~10 μm) falls within the typical application range of hard coatings (balancing wear resistance and process economy). The layered design of the intermediate layer (high silver content) and the top layer (low silver content) ensures a reasonable distribution of antibacterial components by controlling the total thickness. The intermediate layer provides the main antibacterial activity, while the top layer, with its low silver content, reduces the rapid consumption of surface silver. The top layer thickness of less than 500 nm (an extremely thin surface layer) further reduces the direct exposure of silver, utilizing amorphous carbon (sp...)... 2 The main component (silver) works synergistically with a small amount of silver to achieve slow-release antibacterial effect, while avoiding a decrease in hardness or an increase in the coefficient of friction due to an excessively thick silver layer.

[0015] Another object of the present invention is to provide a method for depositing a composite coating as described above on a metal substrate.

[0016] The technical solution is as follows:

[0017] The method for depositing the antibacterial and friction-reducing composite coating as described above on a metal substrate includes the following steps:

[0018] Step 1: Arc target installation and substrate pretreatment:

[0019] Three rows of metal targets are arranged vertically, two of which are vanadium targets and the third is a silver target;

[0020] Polish the metal substrate, then clean the metal substrate with acetone and alcohol in sequence, place the substrate on the vacuum chamber rotating frame, and set the distance between the metal target and the metal substrate to 100~300 mm.

[0021] Step 2: Etching and cleaning of the substrate surface:

[0022] Start the vacuum system and turn on the heating system to raise the temperature to 250~550 ℃. Wait until the background vacuum of the vacuum chamber is lower than 2×10 - 2At Pa, inert gas is introduced and the pressure is controlled between 0.5 and 2 Pa. All arc targets are turned on for target cleaning, and the target material is turned on for 3 to 5 minutes. The filament power supply is turned on, the filament current is set to 10 to 30 A, and the pulse bias voltage is set to -500 to -1000 V for ion cleaning of the metal substrate.

[0023] Step 3: Coating deposition:

[0024] When the background vacuum is lower than 5×10 -3 When Pa is reached, an inert gas is introduced, and two V-targets are activated to deposit the vanadium metal as the bottom layer.

[0025] The acetylene gas flow rate is gradually increased from 0 to 50-100 sccm to deposit the gradient transition layer; 50-300 sccm of acetylene gas is introduced while the silver target is turned on to deposit the vanadium-silver-carbon composite layer; during the deposition process, the pulse bias voltage is -50 to -300 V, the axial magnetic field strength at the center of the target is 30-60 Gs, and the coil current is 0.5-1.5 A.

[0026] In the above technical solution of this invention, the precise construction of the coating structure is achieved through step-by-step process parameter control. Step one employs a two-row vanadium target and a one-row silver target arrangement, providing the target material foundation for subsequent layered deposition (underlayer, transition layer, and composite layer). Substrate pretreatment (polishing + organic solvent cleaning) removes surface oxides and contaminants, ensuring a clean interface between the coating and the substrate. Step two, ion etching cleaning (high vacuum + high temperature + bias ion bombardment), further removes adsorbed gas molecules and weak bonding layers from the substrate surface, while simultaneously improving substrate surface activity, facilitating the tight adhesion of the subsequent coating. Step three involves first depositing pure vanadium as the underlayer, then gradually increasing the acetylene flow rate (from 0 to 50~100 sccm) to achieve a gradient generation of vanadium carbide (vanadium reacts with carbon to form VC), controlling the vanadium carbide content to continuously change from 0 to ≥80 at.%. Finally, during the deposition of the vanadium-silver-carbon composite layer, pulsed bias (-50~-300 V), magnetic field strength (30~60 Gs), and coil current (0.5~1.5) are used. The synergistic regulation of A) optimizes plasma density and energy distribution, promotes uniform co-deposition of silver, vanadium, and carbon, and forms a composite structure containing silver metallic phase, carbide ceramic phase and amorphous carbon phase.

[0027] As a preferred embodiment of the above technical solution, a fourth step, performed after step three, is also included: cooling and sampling.

[0028] The arc target, bias voltage, and gas are turned off in sequence. After maintaining the temperature for at least 30 minutes, the heating system is turned off. The workpiece is removed after the vacuum chamber has cooled down.

[0029] This step, through the sequence of "first turning off the arc target and bias voltage (stopping deposition), then maintaining a constant temperature (avoiding rapid cooling that could lead to stress concentration within the coating), and finally allowing it to cool naturally," ensures that the coating undergoes a slow and controlled cooling process after deposition. This reduces the risk of coating cracking or peeling caused by sudden changes in thermal stress and improves the overall structural integrity and bonding reliability of the coating.

[0030] As a preferred embodiment of the above technical solution, in step one, the purity of the metal target is higher than 99.5%; the material of the metal substrate is selected from one of iron-based alloys, titanium-based alloys, and nickel-based alloys.

[0031] High-purity target materials (>99.5%) reduce the introduction of impurity elements (such as oxygen and nitrogen), avoiding defects such as the formation of brittle phases or reduced antibacterial / wear-resistant properties in the coating; iron-based, titanium-based and nickel-based alloys are selected as substrates, covering commonly used materials in mainstream medical devices and industrial components, enhancing the universality of the solution.

[0032] As a preferred embodiment of the above technical solution, in step three, the working gas pressure during the deposition process is 0.2~2.0 Pa; when using a mixture of inert gas and acetylene to deposit the vanadium-silver-carbon composite layer, the flow ratio of inert gas to acetylene is (2~5):1, and the purity of the gases is higher than 99.9%.

[0033] The working pressure (0.2~2.0 Pa) provides a suitable plasma density environment for multi-arc ion plating. Too low a pressure may lead to plasma instability, while too high a pressure may reduce ion energy. The flow ratio of inert gas (such as argon) to acetylene (carbon source) (2~5):1 controls the proportion of carbide formation (too much acetylene can lead to excessive carbon, while too little acetylene will result in insufficient VC formation). At the same time, high-purity gas (>99.9%) avoids the reaction of impurity gases (such as oxygen and nitrogen) with metal / carbon to form brittle oxides or nitrides, ensuring the purity and performance stability of the coating.

[0034] As a preferred embodiment of the above technical solution, in step three, the vanadium target current during the deposition process is 50~120 A.

[0035] According to analytical techniques, the vanadium target current (50~120 A) determines the evaporation rate and deposition efficiency of vanadium atoms. Too low a current will result in slow deposition of the underlayer or transition layer (affecting efficiency), while too high a current may cause arc spot instability or increased coating roughness. This range ensures uniform deposition of the vanadium metal phase, laying the foundation for subsequent gradient transition and composition control of the composite layer.

[0036] As a preferred embodiment of the above technical solution, during the deposition of the vanadium-silver-carbon composite layer, the top layer of the vanadium-silver-carbon composite layer is deposited by periodically starting and stopping the silver target.

[0037] Periodic start-stop of the silver target enables precise control of the silver content in the top layer. By intermittently turning on the silver target, the continuous input amount of silver atoms is restricted, reducing the surface silver content to 0.5 - 3 at.% (compared with the intermediate layer deposited continuously), thus reducing the risk of excessive exposure and sudden release of surface silver. At the same time, combined with the self-lubricating effect of amorphous carbon, the antibacterial slow-release and low-friction properties of the top layer are optimized.

[0038] As a further optimization of the above technical solution, the top layer of the vanadium-silver-carbon composite layer is deposited by periodically starting and stopping the silver target. Specifically: set the start-stop cycle of the silver target as x min, the single-cycle opening time as y min (y < x) which is less than x, and the coating lasts for n cycles to deposit the said top layer.

[0039] By defining specific start-stop cycles (x min), single-cycle opening times (y min, y < x), and coating cycle numbers (n), periodic regulation of silver atom input is achieved. During the opening period, a silver source is introduced to form local silver enrichment, and during the closing period, silver input is reduced, lowering the surface silver content gradient; this design further refines the silver distribution uniformity, ensuring that the overall silver content in the top layer is stably maintained at 0.5 - 3 at.%. At the same time, through periodic fluctuations, the mixing uniformity of amorphous carbon and silver is promoted, enhancing the comprehensive performance of the top layer (such as antibacterial slow-release stability and lubrication consistency).

[0040] In summary, the present invention has the following beneficial effects:

[0041] 1. Precise gradient composition regulation: Through the hierarchical structure design of the vanadium metal bottom layer, V / VC gradient transition layer (the vanadium carbide content gradually increases from 0 at.% to ≥80 at.%), and vanadium-silver-carbon composite layer (Ag 3 - 20 at.% in the intermediate layer, Ag 0.5 - 3 at.% in the top layer), precise coordination of bonding strength, wear resistance, and antibacterial function is achieved, effectively solving the technical problem that it is difficult to balance wear resistance and antibacterial properties in traditional coatings.

[0042] 2. Optimized interface bonding performance: The gradient transition layer realizes continuous composition transition from vanadium metal phase to vanadium carbide ceramic phase, avoiding sudden changes in interface stress caused by direct contact between metal and ceramic phases, significantly reducing the residual stress inside the coating and the risk of crack initiation, and enhancing the bonding strength between the coating and the metal substrate (such as stainless steel, titanium alloy, etc.) and the long-term service reliability.

[0043] 3. Realization of long-term antibacterial function: The vanadium-silver-carbon composite layer adopts a hierarchical design of "high Ag content (3 - 20 at.%) in the intermediate layer + low Ag content (0.5 - 3 at.%) in the top layer", which not only ensures sufficient silver ion release for efficient antibacterial, but also reduces the risk of sudden release by reducing excessive exposure of surface silver. Combined with the self-lubricating characteristics of amorphous carbon, long-term stable release of antibacterial performance is achieved.

[0044] 4. Excellent tribological properties: amorphous carbon (sp) 2 The self-lubricating properties of the vanadium carbide ceramic phase (primarily vanadium carbide) work synergistically with the load-bearing capacity of the vanadium carbide ceramic phase to exhibit a low and stable coefficient of friction in the room temperature to medium temperature range. The gradient transition layer and multi-layer interlocking structure effectively suppress crack initiation and propagation, significantly improving the wear resistance and anti-fretting wear performance of the coating.

[0045] 6. Controllable process parameter matching: The multi-arc ion plating process, combined with precisely controlled parameters such as acetylene flow gradient (from 0 to 50~100 sccm), pulse bias voltage (-50~-300 V) and magnetic field strength (30~60 Gs), achieves precise deposition and composition control of each functional layer, ensuring the continuity of gradient transition and the stability of the composite layer phase structure.

[0046] 7. Reliable structural integrity assurance: Through optimized coating thickness design (0.1~1 μm for the underlayer, 0.1~2 μm for the gradient transition layer, and 2~10 μm for the composite layer) and strict process flow (including ion etching cleaning, step deposition and controlled cooling), the overall structural uniformity, bonding strength and anti-peeling performance of the coating are improved.

[0047] 8. Wide applicability of substrates: The process solution is compatible with a variety of commonly used medical metal materials such as iron-based alloys, titanium-based alloys and nickel-based alloys, which meets the diverse needs of different medical devices for surface protection and functionalization. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the coating structure described in this invention;

[0049] Figure 2 The EDS spectrum of coating 1 prepared in Example 1 of this invention;

[0050] Figure 3 The scratch morphology of coating 1 prepared in Example 1 of the invention;

[0051] Figure 4 The friction coefficient of coating 1 prepared in Example 1 of the present invention.

[0052] Figure 5 This is a test diagram of the antibacterial performance of Example 1 of the present invention. Detailed Implementation

[0053] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present application.

[0054] Example 1 Coating 1:

[0055] An antibacterial and friction-reducing V-Ag-C composite coating (such as...) Figure 1 As shown), its preparation method includes the following steps:

[0056] (1) Install 3 V targets in each of the two vertical target columns and 3 Ag targets in the third vertical target column, and adjust the axial magnetic field strength at the center of the target material to between 35 and 45 Gs.

[0057] (2) Polish the TC4 titanium alloy substrate with water using 600 grit, 1200 grit, 2500 grit and 5000 grit sandpaper respectively. After polishing, immerse the sample and silicon wafer in stainless steel containers containing petroleum ether, acetone and ethanol solvents for ultrasonic cleaning for 15 min. Then blow dry with compressed air. After wiping the sample to be coated with a lint-free cloth, clamp it on the vacuum chamber rotating frame. The distance between the target and the substrate is between 150 and 250 mm. Start the rotating frame and set the rotation speed to 2 rpm.

[0058] (3) Turn on the heating and vacuum systems, and wait until the chamber temperature reaches 400 ℃ and the vacuum is below 5×10 ℃. -2 At Pa, 1500 sccm of argon gas is introduced, and the gas pressure is controlled at 1.2~1.8 Pa. All arc targets are turned on for target cleaning. The arc target turning time is 5 min. The current of all arc targets is set to 70 A, the pulse bias voltage is -700 V, the duty cycle is 70%, and the pulse frequency is 20 kHz. The filament ion source is turned on, and the filament current is 20 A. The substrate surface is ion cleaned for 30 min.

[0059] (4) Turn off the gas and continue evacuating until the vacuum level in the coating chamber is below 2×10⁻⁶. -3 At Pa, 1500 sccm of argon gas was introduced, and two rows of six V targets were turned on to deposit the metal underlayer. The coating gas pressure was maintained at 1.5 Pa, the V target current was set to 80 A, the axial magnetic field was turned on, the coil current was set to 1.2 A, the pulse bias voltage was -100 V, the duty cycle was 50%, the pulse frequency was 20 kHz, and the deposition time was 10 min.

[0060] (5) Adjust the argon flow rate to 500 sccm, set the acetylene flow rate to increase from 0 to 60 sccm within 20 min, deposit the V / vanadium carbide gradient transition layer, keep the coating pressure between 0.4 and 0.6 Pa, keep the V target current, pulse bias voltage and coil current constant, and the deposition time is 20 min;

[0061] (6) Adjust the V target current to 100 A, turn on the Ag target and set the current to 45 A, the target magnetic field coil current to 1.2 A, set the argon flow rate to 350 sccm, the acetylene flow rate to 150 sccm, the pulse bias to -150 V, the duty cycle to 50%, the pulse frequency to 20 kHz, and the deposition time to 120 min to prepare a V-Ag-C intermediate layer with high Ag content; reduce the Ag target current to 30 A, set the Ag target start-stop cycle to 2 min, the single cycle start time to 1 min, and the coating lasts for 5 cycles. Keep the pulse bias, gas flow rate and coil current unchanged to deposit a V-Ag-C top layer with low Ag content.

[0062] (7) After the coating deposition is completed, turn off the arc target, bias voltage, gas and magnetic field devices, continue to evacuate the vacuum, and turn off the heating system and vacuum system after 30 minutes of constant temperature. Take out the workpiece after the vacuum chamber temperature drops below 100 ℃.

[0063] EDS energy dispersive spectroscopy analysis of coating 1 is shown in [reference needed]. Figure 2 .

[0064] Figure 3 The scratch characterization of coating 1 is given. When the normal load is less than 80 N, no coating peeling occurs inside the scratch, indicating that coating 1 has excellent bonding strength with the substrate and the bonding force exceeds 80 N.

[0065] Figure 4 The friction coefficient of coating 1 as a function of sliding time is shown. The average friction coefficient is 0.2, which shows a good friction reduction effect.

[0066] Figure 5 Antibacterial performance tests were conducted, and the antibacterial rate of the coating reached 99.7% after one hour of contact with Staphylococcus aureus or Escherichia coli, demonstrating excellent antibacterial ability.

[0067] The resulting coating 1 has a silver-gray appearance, a nano-indentation hardness test result of 16.8 GPa, and a total coating thickness of 4.5 μm.

[0068] Example 2 Coating 2:

[0069] An antibacterial and friction-reducing V-Ag-C composite coating (such as...) Figure 1 As shown), its preparation method includes the following steps:

[0070] (1) Install 3 V targets in each of the two vertical target columns and 3 Ag targets in the third vertical target column, and adjust the axial magnetic field strength at the center of the target material to between 35 and 45 Gs.

[0071] (2) Polish the TC4 titanium alloy substrate with water using 600 grit, 1200 grit, 2500 grit and 5000 grit sandpaper respectively. After polishing, immerse the sample and silicon wafer in stainless steel containers containing petroleum ether, acetone and ethanol solvents for ultrasonic cleaning for 15 min. Then blow dry with compressed air. After wiping the sample to be coated with a lint-free cloth, clamp it on the vacuum chamber rotating frame. The distance between the target and the substrate is between 150 and 250 mm. Start the rotating frame and set the rotation speed to 2 rpm.

[0072] (3) Turn on the heating and vacuum systems, and wait until the chamber temperature reaches 400 ℃ and the vacuum is below 5×10 ℃. -2 At Pa, 1500 sccm of argon gas is introduced, and the gas pressure is controlled at 1.2~1.8 Pa. All arc targets are turned on for target cleaning. The arc target turning time is 5 min. The current of all arc targets is set to 70 A, the pulse bias voltage is -700 V, the duty cycle is 70%, and the pulse frequency is 20 kHz. The filament ion source is turned on, and the filament current is 20 A. The substrate surface is ion cleaned for 30 min.

[0073] (4) Turn off the gas and continue evacuating until the vacuum level in the coating chamber is below 2×10⁻⁶. -3 At Pa, 1500 sccm of argon gas was introduced, and two rows of six V targets were turned on to deposit the metal underlayer. The coating gas pressure was maintained at 1.2 Pa, the V target current was set to 80 A, the axial magnetic field was turned on, the coil current was set to 1.2 A, the pulse bias voltage was -100 V, the duty cycle was 50%, the pulse frequency was 20 kHz, and the deposition time was 10 min.

[0074] (5) Adjust the argon flow rate to 500 sccm, set the acetylene flow rate to increase from 0 to 75 sccm within 20 min, deposit the V / vanadium carbide gradient transition layer, keep the coating pressure between 0.4 and 0.6 Pa, keep the V target current, pulse bias voltage and coil current constant, and the deposition time is 30 min;

[0075] (6) Adjust the V target current to 100 A, turn on the Ag target and set the current to 50 A, the target magnetic field coil current to 1.2 A, set the argon flow rate to 350 sccm, the acetylene flow rate to 150 sccm, the pulse bias to -120 V, the duty cycle to 50%, the pulse frequency to 20 kHz, and the deposition time to 150 min to prepare a V-Ag-C intermediate layer with high Ag content; reduce the Ag target current to 35 A, set the Ag target start-stop cycle to 2 min, the single cycle start time to 1 min, and the coating lasts for 5 cycles. Keep the pulse bias, gas flow rate and coil current unchanged to deposit a V-Ag-C top layer with low Ag content.

[0076] (7) After the coating deposition is completed, turn off the arc target, bias voltage, gas and magnetic field devices, continue to evacuate the vacuum, and turn off the heating system and vacuum system after 30 minutes of constant temperature. Take out the workpiece after the vacuum chamber temperature drops below 100 ℃.

[0077] The resulting coating 2 has a silver-gray appearance, a nano-indentation hardness of 15.6 GPa, a total coating thickness of 6.7 μm, and excellent antibacterial ability. After one hour of contact with Staphylococcus aureus or Escherichia coli, the antibacterial rate reaches 99.9%.

[0078] Example 3 Coating 3:

[0079] An antibacterial and friction-reducing V-Ag-C composite coating (such as...) Figure 1 As shown), its preparation method includes the following steps:

[0080] (1) Install 3 V targets in each of the two vertical target columns and 3 Ag targets in the third vertical target column, and adjust the axial magnetic field strength at the center of the target material to between 35 and 45 Gs.

[0081] (2) Polish the 304 stainless steel substrate with water using 600 grit, 1200 grit, 2500 grit and 5000 grit sandpaper respectively. After polishing, immerse the sample and silicon wafer in stainless steel containers containing petroleum ether, acetone and ethanol solvents for ultrasonic cleaning for 15 min. Then blow dry with compressed air. After wiping the sample to be coated with a lint-free cloth, clamp it on the vacuum chamber rotating frame. The distance between the target and the substrate is between 150 and 250 mm. Start the rotating frame and set the rotation speed to 2 rpm.

[0082] (3) Turn on the heating and vacuum systems, and wait until the chamber temperature reaches 450 ℃ and the vacuum is below 5×10 -2 At Pa, 2000 sccm of argon gas is introduced, and the gas pressure is controlled at 1.8~2.0 Pa. All arc targets are turned on for target cleaning for 5 min. The current of all arc targets is set to 80 A, the pulse bias voltage is -700 V, the duty cycle is 70%, and the pulse frequency is 20 kHz. The filament ion source is turned on with a filament current of 20 A, and the substrate surface is ion cleaned for 60 min.

[0083] (4) Turn off the gas and continue evacuating until the vacuum level in the coating chamber is below 2×10⁻⁶. -3 At Pa, 1500 sccm of argon gas was introduced, and two rows of six V targets were turned on to deposit the metal underlayer. The coating gas pressure was maintained at 1.2 Pa, the V target current was set to 80 A, the axial magnetic field was turned on, the coil current was set to 1.2 A, the pulse bias voltage was -100 V, the duty cycle was 50%, the pulse frequency was 20 kHz, and the deposition time was 10 min.

[0084] (5) Adjust the argon flow rate to 500 sccm, set the acetylene flow rate to increase from 0 to 75 sccm within 20 min, deposit the V / vanadium carbide gradient transition layer, keep the coating pressure between 0.4 and 0.6 Pa, keep the V target current, pulse bias voltage and coil current constant, and the deposition time is 15 min;

[0085] (6) Adjust the V target current to 100 A, turn on the Ag target and set the current to 50 A, the target magnetic field coil current to 1.2 A, set the argon flow rate to 350 sccm, the acetylene flow rate to 150 sccm, the pulse bias to -200 V, the duty cycle to 50%, the pulse frequency to 20 kHz, and the deposition time to 100 min to prepare a V-Ag-C intermediate layer with high Ag content; reduce the Ag target current to 30 A, set the Ag target start-stop cycle to 3 min, the single cycle start time to 1 min, and the coating lasts for 3 cycles. Keep the pulse bias, gas flow rate and coil current unchanged to deposit a V-Ag-C top layer with low Ag content.

[0086] (7) After the coating deposition is completed, turn off the arc target, bias voltage, gas and magnetic field devices, continue to evacuate the vacuum, and turn off the heating system and vacuum system after 30 minutes of constant temperature. Take out the workpiece after the vacuum chamber temperature drops below 100 ℃.

[0087] The resulting coating 2 has a silver-gray appearance, a nano-indentation hardness of 17.5 GPa, a total coating thickness of 3.6 μm, and excellent antibacterial ability. After one hour of contact with Staphylococcus aureus or Escherichia coli, the antibacterial rate reaches 99.8%.

[0088] It should be understood that the above embodiments are only used to illustrate the technical concept and features of the invention, and their purpose is to enable those skilled in the art to understand and implement the invention, but this does not limit the scope of protection of the invention. Any equivalent changes or improvements made based on the spirit and essence of the invention should be included within the scope of protection of the invention.

Claims

1. An antibacterial and friction-reducing composite coating for a metal substrate, formed on the surface of a metal substrate by a multi-arc ion plating process, characterized in that, The layers, arranged in sequence away from the surface of the metal substrate, include a vanadium metal underlayer, a gradient transition layer, and a vanadium-silver-carbon composite layer. The gradient transition layer comprises a vanadium metal phase and a vanadium carbide ceramic phase, wherein the vanadium carbide content increases from 0 to not less than 80 at.% along the direction away from the metal substrate. The vanadium-silver-carbon composite layer comprises a silver metallic phase, a carbide ceramic phase, and an amorphous carbon phase, including an intermediate layer with a silver content of 3~20 at.% and a top layer with a silver content of 0.5~3 at.%.

2. The composite coating for antibacterial and friction-reducing properties on a metal substrate surface according to claim 1, characterized in that: The thickness of the gradient transition layer is 1 to 3 times that of the vanadium metal underlayer; the thickness of the vanadium metal underlayer is 0.1 to 1 μm.

3. The antibacterial and friction-reducing composite coating for a metal substrate surface according to claim 1 or 2, characterized in that: The thickness of the vanadium-silver-carbon composite layer is 2~10 μm; wherein the thickness of the top layer is less than 500 nm.

4. The method for preparing an antibacterial and friction-reducing composite coating on a metal substrate as described in claim 1, characterized in that, Includes the following steps: Step 1: Arc target installation and substrate pretreatment: Three rows of metal targets are arranged vertically, two of which are vanadium targets and the third is a silver target; Polish the metal substrate, then clean the metal substrate with acetone and alcohol in sequence, place the substrate on the vacuum chamber rotating frame, and keep the distance between the target and the metal substrate 100~300 mm. Step 2: Etching and cleaning of the substrate surface: Start the vacuum system and turn on the heating system to raise the temperature to 250~550 ℃. Wait until the background vacuum of the vacuum chamber is lower than 2×10 -2 At Pa, inert gas is introduced and the gas pressure is controlled between 0.5 and 2 Pa. All arc targets are turned on for target cleaning, and the target material is turned on for 3 to 5 minutes. The filament power supply is turned on, the filament current is set to 10 to 30 A, and the pulse bias voltage is set to -500 to -1000 V for ion cleaning of the metal substrate. Step 3: Coating deposition: When the background vacuum is lower than 5×10 -3 When Pa is reached, an inert gas is introduced, and two V-targets are activated to deposit the vanadium metal as the bottom layer. The acetylene gas flow rate is gradually increased from 0 to 50-100 sccm to deposit the gradient transition layer; 50-300 sccm of acetylene gas is introduced while the silver target is turned on to deposit the vanadium-silver-carbon composite layer; during the deposition process, the pulse bias voltage is -50 to -300V, the axial magnetic field strength at the center of the target is 30-60 Gs, and the coil current is 0.5-1.5 A.

5. The method according to claim 4, characterized in that, In step three, the bias voltage of the vanadium-silver-carbon intermediate layer is lower than that of the top vanadium-silver-carbon layer. The bias voltage of the vanadium-silver-carbon intermediate layer is -40~-120 V, and the bias voltage of the top vanadium-silver-carbon layer is -100~-180 V.

6. The method according to claim 4, characterized in that: In step one, the purity of the metal target is higher than 99.5%; the metal substrate is selected from one of iron-based alloys, titanium-based alloys and nickel-based alloys.

7. The method according to claim 4, characterized in that: In step three, the working gas pressure during the deposition process is 0.2~2.0 Pa; when depositing the vanadium-silver-carbon composite layer using a mixture of inert gas and acetylene, the flow ratio of inert gas to acetylene is (2~5):1, and the purity of the gas is not less than 99.9%.

8. The method according to claim 4, characterized in that: In step three, the vanadium target current is 50~120A during the deposition process.

9. The method according to claim 4, characterized in that, During the deposition of the vanadium-silver-carbon composite layer, the top layer of the vanadium-silver-carbon composite layer is deposited by periodically starting and stopping the silver target.

10. The method according to claim 9, characterized in that, The top layer of the vanadium-silver-carbon composite layer is deposited by periodically starting and stopping the silver target. Specifically, the start-stop cycle of the silver target is set to x min, the single cycle start time is y min which is less than x, and the coating continues for n cycles to deposit the top layer.

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