A corrosion-resistant and low-friction medical protective coating, its preparation method and application

Abstract

This invention provides a corrosion-resistant, low-friction protective coating, its preparation method, and its application, relating to the field of medical implant protective materials. The invention involves micro-arc oxidation of a titanium alloy substrate to form a micro-arc oxidation layer on the substrate surface. The electrolyte used in the micro-arc oxidation comprises the following components at concentrations: sodium phosphate 5-30 g / L, sodium silicate 5-30 g / L, sodium hydroxide 1-5 g / L, with the balance being water. Using a transition metal diboride as the target material, magnetron sputtering is performed on the surface of the micro-arc oxidation layer to obtain the corrosion-resistant, low-friction protective coating. The protective coating prepared by this invention exhibits excellent corrosion resistance in simulated body fluid environments, effectively adsorbing proteins in the body fluid and utilizing the lubricating function of proteins, thereby reducing the coefficient of friction between the coating and the friction pair, achieving a low wear rate. Furthermore, it possesses good biocompatibility, facilitating cell adsorption and growth.

Description

Technical Field

[0001] This invention relates to the field of medical implant protective materials technology, and in particular to a corrosion-resistant and low-friction protective coating, its preparation method and application. Background Technology

[0002] Statistics show that there are 355 million people with arthritis worldwide, and in Asia, one in six people suffers from arthritis. Artificial joint replacement is a widely used treatment method in hip and knee surgery, aiming to maintain joint mobility and reduce pain. With the increasing aging population, the number of arthritis patients is constantly increasing, thus the demand for artificial joint replacement is also growing. Furthermore, more and more young people are requiring hip or knee replacements, thus creating a need for longer-lasting artificial joints. However, artificial joints, primarily composed of hip or knee replacement materials, replace the original friction environment and face a series of problems caused by wear. For polymer replacement materials, their lower hardness compared to metals results in wear products that are typically large fragments. Metal replacement materials have higher hardness, and their wear products are usually smaller particles, some of which are biotoxic at high local concentrations. These wear products can lead to local rejection reactions, osteolysis, aseptic loosening, and other problems, resulting in implant failure.

[0003] To overcome this problem, alternative materials have been developed, such as metal-to-metal (MoM) prostheses, including CoCrMo and Ti-6Al-4V components. Second-generation MoM prostheses were introduced in the early 1990s. Titanium (Ti) and its alloys (typically Ti-6Al-4V, i.e., TC4) are favored due to their good mechanical strength, excellent corrosion resistance to corrosive media, and low density (4.43 g·cm³). -3 Ti-6Al-4V is preferred for orthopedic implants due to its good biocompatibility. However, its low hardness results in poor resistance to wear damage, leading to the release of numerous wear particles and potential safety issues. Furthermore, when Ti-6Al-4V is exposed to the human body, the spontaneously formed passivation oxide film on its surface ruptures due to wear, severely accelerating corrosion and dissolution at the corresponding sites, which is insufficient to ensure the material's proper performance in the human body. Therefore, a protective coating with good tribological properties is needed to protect joint implants from wear and the safety issues caused by wear-induced corrosion. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a corrosion-resistant, low-friction protective coating, its preparation method, and its application. The protective coating prepared by this invention exhibits excellent corrosion resistance and lubrication properties.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a corrosion-resistant and low-friction protective coating, comprising the following steps:

[0007] A micro-arc oxidation is performed on a titanium alloy substrate to form a micro-arc oxidation layer on the surface of the titanium alloy substrate; the electrolyte used in the micro-arc oxidation includes the following components at the following concentrations: sodium phosphate 5-30 g / L, sodium silicate 5-30 g / L, sodium hydroxide 1-5 g / L, and the balance being water;

[0008] Using transition metal diborides as the target material, magnetron sputtering is performed on the surface of the micro-arc oxide layer to obtain the corrosion-resistant and low-friction protective coating.

[0009] Preferably, the electrical parameters of the micro-arc oxidation include: constant voltage mode, radio frequency power supply frequency of 100-500Hz, positive duty cycle of 5%-20%, negative duty cycle of -5%--20%, positive voltage of 150-400V, negative voltage of 0--50V, and working time of 2-30min.

[0010] Preferably, the surface of the micro-arc oxidation layer has a porous structure, and the pore diameter of the porous structure is less than 3 micrometers.

[0011] Preferably, the transition metal diborides include titanium diboride, tantalum diboride, zirconium diboride, hafnium diboride, or niobium diboride.

[0012] Preferably, the angle between the target material and the horizontal plane is 45°, and the target-substrate distance between the target material and the titanium alloy substrate is 6-10 cm.

[0013] Preferably, the working gas for magnetron sputtering is argon, and the flow rate of the argon is 50–100 sccm; the working pressure for magnetron sputtering is 0.8–1 Pa.

[0014] Preferably, during the magnetron sputtering process, the power of the target material is DC 50-200W, the temperature of the titanium alloy substrate is 25-500℃, the voltage applied to the titanium alloy substrate is 0-130V, and the magnetron sputtering time is 20min-6h.

[0015] The present invention provides a corrosion-resistant and low-friction protective coating prepared by the preparation method described above, comprising a micro-arc oxidation layer and a transition metal diboride layer deposited on the surface of the micro-arc oxidation layer, wherein the micro-arc oxidation layer comprises oxides of titanium, phosphorus and silicon.

[0016] Preferably, the thickness of the micro-arc oxide layer is 1 to 10 micrometers, and the thickness of the transition metal diboride layer is 0.1 to 3 micrometers.

[0017] This invention provides the application of the corrosion-resistant and low-friction protective coating described above in the preparation of medical implants.

[0018] This invention provides a method for preparing a corrosion-resistant and low-friction protective coating, comprising the following steps: micro-arc oxidation of a titanium alloy substrate to form a micro-arc oxide layer on the surface of the titanium alloy substrate; the electrolyte used in the micro-arc oxidation comprises the following components at the following concentrations: sodium phosphate 5-30 g / L, sodium silicate 5-30 g / L, sodium hydroxide 1-5 g / L, with the balance being water; using a transition metal diboride as a target, magnetron sputtering is performed on the surface of the micro-arc oxide layer to obtain the corrosion-resistant and low-friction protective coating. This invention first performs micro-arc oxidation on the surface of the titanium alloy substrate, followed by magnetron sputtering. The micro-arc oxide layer formed is an oxide of titanium, phosphorus, and silicon, which has high chemical inertness and strong stability, exhibiting good corrosion resistance. However, its porous structure is not conducive to blocking corrosive media. In contrast, the transition metal diboride layer formed by magnetron sputtering is dense and chemically inert, capable of filling the pores of the micro-arc oxide layer and improving corrosion resistance. Furthermore, the micro-arc oxide layer is obtained through reactive growth and has good adhesion to the substrate, making it less prone to detachment during friction. The transition metal diboride layer formed by magnetron sputtering deposition has high hardness and is not easily worn. In addition, the transition metal diboride layer can adsorb proteins in body fluids and play a lubricating role, reducing the coefficient of friction.

[0019] This invention provides a corrosion-resistant, low-friction protective coating prepared by the method described above. The protective coating provided by this invention exhibits excellent corrosion resistance in simulated body fluid environments, effectively adsorbs proteins in the body fluid, and utilizes the lubricating function of proteins, thereby reducing the coefficient of friction between the coating and the friction pair, achieving a low wear rate. Furthermore, it possesses good biocompatibility, facilitating cell adsorption and growth. The corrosion-resistant, low-friction protective coating provided by this invention can be used in the preparation of medical implants. Attached Figure Description

[0020] Figure 1 The electrolytic cell and power supply for micro-arc oxidation in Example 1 are shown. Figure 1 In the image, (a) is a micro-arc oxidation power source, and (b) is an electrolytic cell;

[0021] Figure 2 This is a diagram showing the positional relationship between the TiB2 target and the MAO sample (substrate) in Example 1;

[0022] Figure 3 The images are scanning electron microscope (SEM) images of the surfaces of the MAO coating obtained by the micro-arc oxidation step in Example 1 and the TiB2 coating obtained after magnetron sputtering, where (a) corresponds to the MAO coating and (b) corresponds to the TiB2 coating.

[0023] Figure 4 The images show the wear morphology of the protective coatings finally obtained in Example 1 and Comparative Examples 1-3.

[0024] Figure 5 The following are the potentiodynamic polarization curves of the protective coatings finally obtained in Example 1 and Comparative Examples 1-3. Detailed Implementation

[0025] This invention provides a method for preparing a corrosion-resistant and low-friction protective coating, comprising the following steps:

[0026] A micro-arc oxidation is performed on a titanium alloy substrate to form a micro-arc oxidation layer on the surface of the titanium alloy substrate; the electrolyte used in the micro-arc oxidation includes the following components at the following concentrations: sodium phosphate 5-30 g / L, sodium silicate 5-30 g / L, sodium hydroxide 1-5 g / L, and the balance being water;

[0027] Using transition metal diborides as the target material, magnetron sputtering is performed on the surface of the micro-arc oxide layer to obtain the corrosion-resistant and low-friction protective coating.

[0028] This invention involves micro-arc oxidation (MAO) on a titanium alloy substrate to form a micro-arc oxide layer on the substrate surface. This invention does not have specific requirements for the titanium alloy substrate; any titanium alloy well-known to those skilled in the art can be used. In this embodiment, the titanium alloy is preferably TC4 titanium alloy; this titanium alloy possesses excellent mechanical and biological properties. Before micro-arc oxidation, this invention preferably pre-treats the titanium alloy substrate. The pre-treatment preferably includes: ultrasonically cleaning the titanium alloy substrate sequentially in acetone, ethanol, and water, and drying the substrate with nitrogen gas after each ultrasonic cleaning. In this invention, the water is preferably deionized water, the power of each ultrasonic cleaning is preferably independently 220–260 W, and the time of each ultrasonic cleaning is preferably independently 15–20 min.

[0029] In this invention, the electrolyte used in the micro-arc oxidation comprises the following components at the following concentrations: sodium phosphate 5-30 g / L, preferably 10-25 g / L, more preferably 20 g / L; sodium silicate 5-30 g / L, preferably 10-20 g / L, more preferably 10 g / L; sodium hydroxide 1-5 g / L, preferably 2-4 g / L, more preferably 2 g / L; and the balance is water. In this invention, the electrolyte is obtained by adding sodium phosphate, sodium silicate, and sodium hydroxide to water and stirring until completely dissolved; the water is preferably deionized water.

[0030] In this invention, the preferred electrical parameters for the micro-arc oxidation include: a constant voltage mode; a radio frequency power supply frequency of 100–500 Hz, preferably 200–300 Hz; a positive duty cycle of 5%–20%, preferably 10%–15%; a negative duty cycle of -5%–-20%, preferably -10%–-15%; a positive voltage of 150–400 V, preferably 200–300 V; a negative voltage of 0–-50 V, preferably -10–-20 V; and a working time of 2–30 min, preferably 5–10 min. This invention does not impose any special requirements on the equipment used for the micro-arc oxidation; any micro-arc oxidation equipment well-known to those skilled in the art can be used. The specific operation of the micro-arc oxidation in this invention is as follows: the electrolyte is placed in an electrolytic cell; the titanium alloy substrate is connected to the anode of the micro-arc oxidation power supply and placed in the electrolyte; the electrolytic cell is connected to the cathode of the micro-arc oxidation power supply; and this process maintains that the titanium alloy substrate and the electrolytic cell do not directly contact each other. During the micro-arc oxidation process, it is preferable to stir the electrolyte in the electrolytic cell, and the stirring rate is preferably 2 revolutions per second.

[0031] During the micro-arc oxidation process, a voltage is applied to the titanium alloy substrate. As the voltage increases, passivation occurs on the substrate surface, forming a thin oxide film. When the voltage continues to increase and reaches a certain critical value, the weak areas of the passivation film are broken down, forming a discharge channel, and spark discharge occurs on the metal surface. Under continuous oxidation with the applied voltage, the spark discharge becomes increasingly intense, accompanied by a series of complex physicochemical reactions within the discharge channel, ultimately forming a coating. The surface of the micro-arc oxidation coating has a porous structure due to the spark discharge channel, and the coating generally consists of an inner dense layer and an outer porous layer.

[0032] In this invention, after micro-arc oxidation, the resulting coating is preferably ultrasonically cleaned with deionized water and then dried with nitrogen gas; the ultrasonic cleaning time is preferably 15 minutes. In this invention, the surface of the micro-arc oxidized layer has a porous structure, and the pore diameter of the porous structure is preferably less than 3 micrometers.

[0033] The present invention uses the electrolyte to perform micro-arc oxidation on the titanium alloy substrate. The resulting micro-arc oxide layer is an oxide of titanium, phosphorus and silicon, which has high chemical inertness, strong stability and good corrosion resistance. Furthermore, the micro-arc oxide layer is obtained through reactive growth and has good adhesion to the substrate, making it less likely to fall off during friction.

[0034] After forming the micro-arc oxide layer, this invention uses transition metal diborides as targets and performs magnetron sputtering (PVD) on the surface of the micro-arc oxide layer to obtain the corrosion-resistant and low-friction protective coating. In this invention, the transition metal diborides preferably include titanium diboride, tantalum diboride, zirconium diboride, hafnium diboride, or niobium diboride; the purity of the target material is preferably 99–99.99%; the target material is preferably cylindrical, with a diameter preferably 40–80 mm, more preferably 60 mm, and a thickness preferably 5 mm. In embodiments of this invention, two targets are preferably used, and there are no particular requirements for the distance between the two targets. In this invention, the angle between the target material and the horizontal plane is preferably 45°, and the target-substrate distance between the target material and the titanium alloy substrate is preferably 6–10 cm, more preferably 8 cm. By adopting the above positional relationship, this invention can ensure that the target material glows and the released plasma is uniformly deposited onto the substrate surface.

[0035] In this invention, before the magnetron sputtering, the target material is preferably pre-sputtered to remove impurities such as oxides from the target surface. In this invention, the pre-sputtering is preferably performed under an argon atmosphere, with the target power preferably at 100W and the time preferably at 15–20 minutes. During the pre-sputtering process, the substrate surface is preferably shielded to prevent plasma glow from reaching the substrate surface.

[0036] In this invention, the working gas for magnetron sputtering is preferably argon, i.e., argon is used as the discharge gas. Preferably, the magnetron sputtering deposition chamber is first evacuated, and then argon is introduced into the deposition chamber; the vacuum level is preferably 6 × 10⁻⁶. -5 Pa. In this invention, the flow rate of the argon gas is preferably 50-100 sccm, more preferably 60 sccm; the working pressure of the magnetron sputtering is preferably 0.8-1 Pa, more preferably 0.8 Pa. During the magnetron sputtering process, the power of the target material is preferably 50-200 W DC, more preferably 75-100 W DC. This invention preferably uses a DC power supply to drive the target material to ignite; the temperature of the titanium alloy substrate is preferably 25-500℃, more preferably 100-300℃; the voltage applied to the titanium alloy substrate is preferably 0--130V, more preferably -80V--100V; the magnetron sputtering time is preferably 20 min-6 h.

[0037] After the magnetron sputtering is completed, the resulting coating is preferably placed in an inert atmosphere to cool naturally to room temperature, and then placed in an atmospheric environment.

[0038] This invention utilizes transition metal diborides as targets for magnetron sputtering on the surface of a micro-arc oxide layer. The magnetron sputtered transition metal diboride layer is dense and chemically inert, capable of filling the pores in the micro-arc oxide layer and improving corrosion resistance. Furthermore, the magnetron sputtered transition metal diboride layer exhibits high hardness and is resistant to wear. In addition, the transition metal diboride layer can adsorb proteins in body fluids and exert the lubricating function of proteins, reducing the coefficient of friction.

[0039] This invention provides a corrosion-resistant, low-friction protective coating prepared by the method described above, comprising a micro-arc oxidation layer and a transition metal diboride layer deposited on the surface of the micro-arc oxidation layer. The micro-arc oxidation layer comprises oxides of titanium, phosphorus, and silicon. In this invention, the thickness of the micro-arc oxidation layer is preferably 1–10 micrometers, more preferably 3 micrometers, and the thickness of the transition metal diboride layer is preferably 0.1–3 micrometers, more preferably 1 micrometer. In this invention, the transition metal diboride layer may also contain a small amount of oxygen, which comes from two sources: oxygen detected in the micro-arc oxidation layer during the detection process, and a small amount of oxygen present inside the target material during the preparation process. The protective coating provided by this invention exhibits excellent corrosion resistance in simulated body fluid environments, effectively adsorbing proteins in the body fluid and utilizing the lubricating function of the proteins, thereby reducing the coefficient of friction between the coating and the friction pair, achieving a low wear rate; it also possesses good biocompatibility, facilitating cell adsorption and growth.

[0040] This invention provides the application of the corrosion-resistant and low-friction protective coating described above in the preparation of medical implants. This invention does not impose any particular requirements on the method of application; any application method well-known to those skilled in the art can be used. Specifically, the protective coating can serve as an anti-corrosion coating for medical implants.

[0041] To further illustrate the present invention, the corrosion-resistant and low-friction protective coating, its preparation method, and its application provided by the present invention are described in detail below with reference to examples, but these should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] Substrate pretreatment: Before the experiment, the titanium alloy (TC4) was ultrasonically cleaned. The titanium alloy was placed in acetone, ethanol and deionized water and ultrasonically cleaned for 15 minutes each. After each step, it was dried with nitrogen gas to obtain a clean substrate.

[0044] Prepare the electrolyte: Dissolve 60g sodium phosphate, 30g sodium silicate, and 6g sodium hydroxide in 3L of deionized water and stir until completely dissolved. Pour the solution into the electrolytic cell. Figure 1 (as shown in (b)).

[0045] Micro-arc oxidation (MAO) step: The treated titanium alloy is connected to a MAO power source ( Figure 1 The anode (shown in (a)) was placed in an electrolytic cell immersed in the electrolyte. The electrolytic cell was connected to the cathode of the MAO power supply, ensuring that the titanium alloy did not directly contact the electrolytic cell. During the experiment, the electrolyte in the electrolytic cell was stirred at a rate of 2 rpm. The MAO power supply used a constant voltage mode with a frequency of 300 Hz, a positive duty cycle of 10%, a negative duty cycle of -10%, a constant positive voltage of 300 V, and a negative voltage of -20 V for 5 minutes. The sample obtained from the MAO process was ultrasonically cleaned with deionized water for 15 minutes and dried with nitrogen gas, serving as the substrate for the PVD step. The elemental contents of the resulting coating were Ti (21.8 at.%), O (68.1 at.%), Si (3.9 at.%), and P (6.2 at.%).

[0046] Magnetron sputtering (PVD) steps: Target placement and vacuuming of the coating chamber: Place the TiB2 target into the target stage, then place the MAO sample into the sample tray. The positions of the TiB2 target and the MAO sample (substrate) are as follows: Figure 2 As shown, the angle between the TiB2 target and the horizontal plane is 45°, and the target-substrate distance between the TiB2 target and the substrate is 8.0 cm. The coating chamber and the vent valve are closed. Then, the pressure in the coating chamber is sequentially pumped down to 6 × 10⁻⁶ using a mechanical pump and a molecular pump. -5 Pa;

[0047] Pre-sputtering: Before sample preparation begins, the TiB2 target is air-sputtered for 20 minutes in an argon atmosphere using a DC power supply of 100W. During sputtering, the sample baffle is kept closed to prevent plasma glow from shining onto the MAO sample.

[0048] Formal sputtering: After completing the above steps, according to the pre-designed experimental parameters, connect the TiB2 target to a DC power supply with a power of 100W; adjust the target-substrate distance to 8.0cm, introduce argon gas and maintain the working pressure of the coating chamber at 0.8-1Pa through the regulating valve, with an argon gas flow rate of 60sccm; adjust the temperature control system to raise the temperature of the MAO sample to 300℃, and apply a bias voltage of -80V to the substrate.

[0049] End of experiment: After 2 hours, the power was turned off, sputtering was stopped, and the coating was allowed to cool naturally to room temperature in an argon atmosphere before being removed and placed in an atmospheric environment to obtain the composite coating, which is the corrosion-resistant and low-friction protective coating. Surface composition of the composite coating: Ti (32.3 at.%), B (63.3 at.%), O (4.4 at.%).

[0050] Figure 3These are scanning electron microscope (SEM) images of the surfaces of the MAO coating obtained by the micro-arc oxidation step and the TiB2 coating obtained after magnetron sputtering, where (a) corresponds to the MAO coating and (b) corresponds to the TiB2 coating. Figure 3 It can be seen that the MAO coating surface has a porous structure with pore diameters of less than 3 micrometers. The TiB2 coating grows on the MAO layer surface, maintaining the porous morphology but with a significantly reduced pore diameter.

[0051] The performance of the obtained protective coating was tested.

[0052] Friction Test: The composite coating was subjected to friction tests in SBF simulated body fluid (pH 7.4) containing protein (0.25 mg / mL). Test conditions: applied load 1 N, sliding speed 2 cm / s, friction trajectory diameter 6 mm, friction pair was alumina, and an MFTR4000 friction corrosion apparatus from the Lanzhou Institute of Chemical Physics, China was used. Test Results: The coefficient of friction remained stable at 0.11, the open circuit potential decreased by 0.001 V during friction, and no significant wear was observed after more than 5000 cycles over 3 hours (wear rate was very small, almost incalculable, less than 1 × 10⁻⁶). -7 mm / N·m).

[0053] Corrosion resistance test: After immersion in SBF simulated body fluid (protein-free) for 168 hours, the corrosion resistance test was conducted using an electrochemical workstation (CORRTEST CS350H). The measurement employed a typical three-electrode setup, including a reference electrode (saturated calomel electrode), a counter electrode (1 cm² area), and a reference electrode (saturated calomel electrode). 2 High-purity platinum sheet and working electrode (sample) were used, and potential polarization tests were performed at a scan rate of 1 mV / s. Test results: The corrosion current density of the composite coating was 2.7 × 10⁻⁶. -9 A / cm 2 The electrochemical impedance value is 2×10 6 Ωcm 2 .

[0054] Example 2

[0055] The preparation method differs from Example 1 in that, when preparing the electrolyte, 30g of sodium phosphate, 30g of sodium silicate, and 6g of sodium hydroxide are added to 3L of deionized water and stirred until completely dissolved. The rest is the same as in Example 1. The elemental contents of the coating obtained after the MAO step are Ti (23.5 at.%), O (69.5 at.%), Si (4 at.%), and P (3 at.%).

[0056] The final composite coating exhibits essentially the same friction and corrosion resistance properties as in Example 1.

[0057] Example 3

[0058] The preparation method differs from Example 1 in that, when preparing the electrolyte, 30g of sodium phosphate, 60g of sodium silicate, and 6g of sodium hydroxide are added to 3L of deionized water and stirred until completely dissolved. The rest is the same as in Example 1. The elemental contents of the coating obtained after the MAO step are Ti (23 at.%), O (67.8 at.%), Si (7.2 at.%), and P (2 at.%).

[0059] The final composite coating exhibits essentially the same friction and corrosion resistance properties as in Example 1.

[0060] Example 4

[0061] The preparation method differs from that in Example 1 in that the TiB2 target power is set to 75W during the formal sputtering in the PVD step, while the rest is the same as in Example 1.

[0062] The final composite coating was immersed in SBF simulated body fluid for 168 hours and then subjected to corrosion resistance testing. The test results showed that the corrosion current density of the composite coating was 3.5 × 10⁻⁶. -9 A / cm 2 The electrochemical impedance value is 1.3 × 10⁻⁶. 6 Ωcm 2 .

[0063] Comparative Example 1

[0064] Compared with a titanium alloy (TC4) substrate.

[0065] A friction experiment was conducted on a titanium alloy substrate in SBF simulated body fluid containing protein (0.25 mg / mL). The friction experiment conditions were the same as in Example 1. The friction test results were: a friction coefficient of 0.45, an open circuit potential decrease of 0.68 V during the friction process, and a wear rate of 4.37 × 10⁻⁶ after 3 hours of friction experiment. -4 The wear resistance was measured at mm / N·m, with a wear track depth of 30 micrometers. After immersion in SBF simulated body fluid for 168 hours, the corrosion resistance test showed that the titanium alloy had a corrosion current density of 5 × 10⁻⁶ mm / N·m. -7 A / cm 2 The electrochemical impedance value is 3×10 5 Ωcm 2 .

[0066] Comparative Example 2

[0067] Compared with the MAO sample, i.e. the sample obtained in the MAO step of Example 1.

[0068] The MAO sample was subjected to a friction experiment in SBF simulated body fluid containing protein (0.25 mg / mL). The friction experiment conditions were the same as in Example 1. The friction test results were: a friction coefficient of 0.6, an open circuit potential decrease of 0.04 V during the friction process, and a wear rate of 6.24 × 10⁻⁶ after 3 hours of friction experiment. -7 mm / N·m; After immersion in SBF simulated body fluid for 168 hours, corrosion resistance testing was conducted, and the corrosion current density of the MAO sample was 4.2 × 10 mm / N·m. -9 A / cm 2 The electrochemical impedance value is 1.2 × 10⁻⁶. 6 Ωcm 2 .

[0069] Comparative Example 3

[0070] Compared with the PVD sample, the MAO removal step in Example 1 only retains the PVD step.

[0071] The PVD sample was subjected to a friction experiment in SBF simulated body fluid containing protein (0.25 mg / mL). The friction experiment conditions were the same as in Example 1. The friction test results were: a friction coefficient of 0.2, an open circuit potential decrease of 0.012 V during the friction process, and a wear rate of 5.64 × 10⁻⁶ after 3 hours of friction experiment. -6 mm / N·m; After immersion in SBF simulated body fluid for 168 hours, corrosion resistance testing was conducted, and the corrosion current density of the PVD sample was 4.3 × 10 mm / N·m. -7 A / cm 2 The electrochemical impedance value is 3×10 5 Ωcm 2 .

[0072] Figure 4 These are wear morphology diagrams of the protective coatings finally obtained in Examples 1 and Comparative Examples 1-3.

[0073] Figure 5 These are the potentiodynamic polarization curves of the protective coatings finally obtained in Example 1 and Comparative Examples 1-3, based on... Figure 5 The test results, fitted using the Tafel extrapolation method, are shown in Table 1. A higher corrosion current density indicates a higher corrosion rate and poorer corrosion resistance.

[0074] Table 1. Corrosion current density of the protective coatings obtained in Example 1 and Comparative Examples 1-3

[0075]

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a corrosion-resistant and low-friction protective coating, characterized in that, Includes the following steps: A micro-arc oxidation is performed on a titanium alloy substrate to form a micro-arc oxidation layer on the surface of the titanium alloy substrate. The electrolyte used in the micro-arc oxidation comprises the following components at the following concentrations: sodium phosphate 5~30 g / L, sodium silicate 5~30 g / L, sodium hydroxide 1~5 g / L, with the remainder being water; Using transition metal diborides as the target material, magnetron sputtering is performed on the surface of the micro-arc oxide layer to obtain the corrosion-resistant and low-friction protective coating; the transition metal diborides are selected from titanium diboride, tantalum diboride, zirconium diboride, hafnium diboride or niobium diboride.

2. The preparation method according to claim 1, characterized in that, The electrical parameters of the micro-arc oxidation include: constant voltage mode, radio frequency power supply frequency of 100~500Hz, positive duty cycle of 5%~20%, negative duty cycle of -5%~-20%, positive voltage of 150~400V, negative voltage of 0~-50V, and working time of 2~30min.

3. The preparation method according to claim 1 or 2, characterized in that, The surface of the micro-arc oxidation layer has a porous structure with a pore diameter of less than 3 micrometers.

4. The preparation method according to claim 1, characterized in that, The angle between the target material and the horizontal plane is 45°, and the target-substrate distance between the target material and the titanium alloy substrate is 6~10cm.

5. The preparation method according to claim 1, characterized in that, The working gas for magnetron sputtering is argon, and the flow rate of the argon is 50~100 sccm; the working pressure for magnetron sputtering is 0.8~1 Pa.

6. The preparation method according to claim 1, characterized in that, During the magnetron sputtering process, the power of the target material is DC 50~200W, the temperature of the titanium alloy substrate is 25~500℃, the voltage applied to the titanium alloy substrate is 0~-130V, and the magnetron sputtering time is 20min~6h.

7. The corrosion-resistant and low-friction protective coating prepared by the preparation method according to any one of claims 1 to 6 comprises a micro-arc oxidation layer and a transition metal diboride layer deposited on the surface of the micro-arc oxidation layer, wherein the micro-arc oxidation layer comprises oxides of titanium, phosphorus and silicon.

8. The corrosion-resistant and low-friction protective coating according to claim 7, characterized in that, The thickness of the micro-arc oxide layer is 1 to 10 micrometers, and the thickness of the transition metal diboride layer is 0.1 to 3 micrometers.

9. The application of the corrosion-resistant and low-friction protective coating of claim 7 or 8 in the preparation of medical implants.

Images