A medical TC4 titanium alloy with a surface texture filled with a lubricating medium and a preparation method thereof

Abstract

The present invention provides a medical TC4 titanium alloy with a surface texture filled with a lubricating medium and a preparation method thereof. The method uses a nanosecond laser to prepare a surface texture with a certain depth at an appropriate power and frequency, and takes it as the positive electrode of the electrode. Through electrophoresis, the charged lubricating medium in the solution is filled into the texture, which can improve the friction reduction and anti-wear performance of the medical TC4 titanium alloy. The present invention directly processes the surface texture on the medical metal using a nanosecond laser, which has low cost, rapid processing, and no pollution. The present invention uses electrophoresis to conduct directional enrichment of the lubricating medium, with simple operation, high feasibility, high enrichment efficiency, and strong controllability. The present invention has directionally filled lubricating medium particles in the texture on the material surface, greatly improving the tribological performance of the medical TC4 titanium alloy, and is expected to increase the service life of friction components.

Description

Technical Field

[0001] The present invention belongs to the field of machining and improving lubrication of moving parts, and relates to a medical TC4 titanium alloy with a surface texture filled with a lubricating medium and a preparation method thereof. Background Art

[0002] Due to its good biocompatibility and non-toxic and harmless properties, titanium alloy is widely used as a metal implant material in clinical medicine, mainly for surgical instruments, artificial joints in orthopedics, implants in dentistry, cardiac pacemakers, and cardiovascular stents. However, currently, the trend in researching medical titanium alloys is towards having a longer service life, fewer adverse reactions, and higher corrosion resistance. However, titanium alloys have a low hardness, a large friction coefficient, and poor wear resistance, and these defects have a greater impact on their mechanical reliability and safety to a large extent.

[0003] In order to eliminate the possible effects of titanium alloy in the human body due to its own defects and improve the wear resistance of titanium alloy, many surface modification technologies have been applied to the surface of titanium alloy. Surface modification methods can be generally divided into electroless plating, sol-gel, micro-arc oxidation, and anodic oxidation. The Chinese invention patent application with publication number CN109609905A discloses a high-hardness erosion-resistant and wear-resistant composite coating, a preparation method and an application thereof. Using TC4 titanium alloy as a substrate, a Cr bonding layer and a Cr / CrSiN working layer are chemically deposited on the substrate material, improving the hardness, wear resistance, and erosion resistance of the titanium alloy; the Chinese invention patent application with publication number CN108103428A discloses a surface treatment method for medical metal materials, using a laser to texture the surface of the medical metal, ablating or inducing a surface structure with a micron-level or nano-level and stacked by multiple rings, reducing the friction coefficient of the surface of the medical metal titanium alloy; the Chinese invention patent application with publication number CN109137036A discloses a composite coating of a ceramic layer grafted with hydrogel on the surface of a titanium alloy and a preparation method thereof. First, the surface of the TC4 titanium alloy is textured by a laser, then a hard ceramic film is formed on the textured titanium alloy surface by micro-arc oxidation, and finally a polyion complex is prepared on the ceramic film by ultraviolet irradiation, having strong wear and corrosion resistance.

[0004] However, as an implantable metal material, medical titanium alloy is used in the human body for a long time, and the metal surface wears severely during use, which may cause various inflammations. Similar problems may also occur in the surface wear-resistant coatings made by surface modification methods. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method for laser surface texturing electrophoresis and filling lubricating medium of medical TC4 titanium alloy to solve the problems in the prior art that medical TC4 titanium alloy has high friction coefficient, is easy to wear, and is easy to cause inflammation during use.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a medical TC4 titanium alloy having a surface texture filled with a lubricating medium comprises the following steps:

[0008] S1. Preparation of surface texture on TC4 alloy surface;

[0009] S2. Using a TC4 alloy with surface texture as the positive electrode, graphite as the negative electrode, and lecithin nanoemulsion as the electrophoresis liquid, a medical TC4 titanium alloy with surface texture filled with a lubricating medium is obtained after electrophoresis.

[0010] A further improvement of the present invention is:

[0011] Preferably, in S1, the TC4 alloy is ground and polished to a roughness of less than Ra0.02 μm.

[0012] Preferably, the surface texture rate in S1 is 18%, the texture diameter is 200 μm, and the depth is 30 μm.

[0013] Preferably, the surface texture is prepared by nanosecond laser in S1.

[0014] Preferably, the laser wavelength of the nanolaser is 1064nm, the laser power is 1~30W, the light-on delay is -150ms, the light-off delay is 300ms, the corner delay is 100ms, the pulse width is 100ns, the laser spot diameter is 20μm, the laser scanning speed is 500mm / s, the laser processing frequency is 20kHz, and the path filling spacing is 1μm.

[0015] Preferably, in S2, the distance between the positive electrode and the negative electrode during the electrophoresis process is 3 to 6 cm.

[0016] Preferably, in S2, during the electrophoresis process, the electrophoresis voltage is 5 to 20 V, and the electrophoresis time is 5 to 10 min.

[0017] Preferably, the concentration of the lecithin nanoemulsion is 0.1 to 0.4 wt %;

[0018] Preferably, sodium dodecylbenzenesulfonate is added to the lecithin nanoemulsion.

[0019] A medical TC4 titanium alloy with a lubricating medium filled in the above-mentioned surface texture. The surface of the TC4 alloy is provided with a surface texture, and the lubricating medium is filled in the surface texture. The lubricating medium is lecithin particles wrapped by sodium dodecylbenzenesulfonate.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides a method for laser surface filling of a lubricating medium on a medical TC4 titanium alloy. This method uses a nanosecond laser to prepare a surface texture with a certain depth at an appropriate power and frequency, and takes it as the positive electrode of the electrode. Through electrophoresis, the charged lubricating medium in the solution is filled into the texture, which can improve the friction reduction and anti-wear performance of the medical TC4 titanium alloy. The present invention uses a nanosecond laser to directly process the surface texture on the medical metal surface, with low cost, rapid processing, and no pollution. The present invention uses electrophoresis to achieve directional enrichment of the lubricating medium, with simple operation, high feasibility, high enrichment efficiency, and strong controllability. The present invention fills the lubricating medium particles in the texture on the material surface directionally, greatly improving the tribological properties of the medical TC4 titanium alloy and promising to extend the service life of friction components. After being processed by a nanosecond laser, the circular texture has some relatively prominent edges, which will form an electric field concentration effect during electrophoresis. The charged lubricating medium particles will be transported directionally into the circular texture under the action of the electric field. As time goes by, the concentration of the lubricating medium particles inside the circular texture will be significantly higher than the surrounding environment. After the lubricating medium particles are enriched in the circular texture, biological macromolecules such as lecithin and protein will form a lubricating film on the material surface through adsorption, improving the lubrication environment of the friction interface and reducing friction and wear. The present invention introduces a mixed solution of lecithin particles and sodium dodecylbenzenesulfonate surfactant as the lubricating medium on the medical metal surface and inside its texture, and does not introduce other substances, does not trigger the body's rejection reaction, and does not interfere with the normal physiological functions of the human body.

[0022] Furthermore, by using electrophoresis technology to achieve the directional enrichment of lubricating medium particles in the circular texture on the surface of the TC4 titanium alloy, the final effect of particle enrichment can be adjusted by controlling the concentration of the nanoemulsion in the solution, the electrophoresis voltage, time, and the distance between the positive and negative electrodes. Among them, the higher the concentration of the nanoemulsion, the greater the voltage intensity, and the longer the time, the more obvious the enrichment of the particles inside the circular texture. In addition, the greater the distance between the positive and negative electrodes, the less obvious the enrichment effect. The more the particles are enriched at the texture, the easier it is to form a lubricating film during friction, thereby reducing the friction coefficient of the titanium alloy surface and improving the wear resistance of the titanium alloy, promising to extend the service life of the implantable titanium alloy in the human body.

[0023] The present invention also discloses a method for laser surface filling of a lubricating medium on a medical TC4 titanium alloy. In this lubricating medium, lecithin is embedded in sodium dodecylbenzenesulfonate, enabling biological macromolecules such as lecithin and proteins to form a lubricating film by adsorbing on the material surface, thus achieving ultra-low friction of the friction pair. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the preparation process of electrophoretic enrichment of microparticles;

[0025] Figure 2 It is the original textured surface;

[0026] Figure 3 It is an image after freeze-drying of the nanoemulsion;

[0027] Figure 4 It is an image of the microparticles enriched in the texture obtained by electrophoresis at 5V voltage for 20 minutes;

[0028] Figure 5 Friction curves of the titanium alloy after enriching the nano-lubricating medium at different voltages. DETAILED DESCRIPTION OF THE INVENTION

[0029] The following further describes the present invention in detail with reference to the drawings and specific embodiments:

[0030] Refer to Figure 1 , the present invention discloses a method for laser surface filling of a lubricating medium on a medical TC4 titanium alloy, which includes the following steps:

[0031] Step 1: Grind and polish the TC4 alloy with sandpaper and then polish it to make its roughness less than Ra0.02μm.

[0032] Step 2: Rinse with deionized water to remove the surface polishing solution and ultrasonicate in an absolute ethanol solution for 10 minutes.

[0033] Step 3: Use a nanosecond laser to prepare a surface texture with a certain depth at an appropriate power and frequency;

[0034] The laser used for preparing the surface texture is a fiber laser, with a laser wavelength of 1064nm, a power of 1 - 30W, a turn-on delay of -150ms, a turn-off delay of 300ms, a corner delay of 100ms, a pulse width of 100ns, a laser spot diameter of 20μm, a laser scanning speed of 500mm / s, a laser processing frequency of 20kHz, and a path filling pitch of 1μm.

[0035] The prepared surface texture ratio is 18%, the texture diameter is 200μm, and the depth is 30μm. After laser processing, the burrs around the texture need to be removed.

[0036] Step 4, weighing lecithin and joining it in 100ml distilled water under stirring, the concentration of lecithin is 0.1~0.4wt%, and sodium dodecylbenzene sulfonate is added after continuing stirring for 10min. Sodium dodecylbenzene sulfonate is used to make the lecithin nanoparticles dispersed and stable in water base. The lecithin emulsion particles carry negative charge. The mass ratio of lecithin and sodium dodecylbenzene sulfonate is (1-1.5): 1. After stirring for 10min, ultrasonic dispersion is carried out for 4min to obtain nanoemulsion.

[0037] In step 5, the TC4 alloy with surface texture is used as the positive electrode of the electrode, and the charged lubricating medium in the solution is filled into the interior of the texture by electrophoresis, thereby improving the friction reduction and anti-wear properties of the medical TC4 titanium alloy.

[0038] The titanium alloy with surface texture is used as the electrophoresis positive electrode, the graphite is used as the negative electrode, the distance between the positive and negative electrodes is 3 to 6 cm, the electrophoresis voltage is 5 to 20 V, and the electrophoresis time is 5 to 15 minutes.

[0039] The lubricating medium is lecithin nanoemulsion, which is dispersed stably in a water base using sodium dodecylbenzenesulfonate and carries negative charges. The concentration of the nanoemulsion is 0.1-0.4 wt%.

[0040] Finally, the surface texture of the TC4 alloy is filled with a lubricating medium, which is lecithin particles wrapped by sodium dodecylbenzenesulfonate.

[0041] Example 1

[0042] (1) Grind the titanium alloy surface with #400, #800, and #1200 sandpaper in turn, and polish it.

[0043] (2) Rinse with deionized water to remove the surface polishing liquid, and ultrasonicate in anhydrous ethanol solution for 10 minutes.

[0044] (3) Adjust the fiber laser power to 18W, the speed to 500mm / s, the light on delay to -150ms, the light off delay to 300ms, the corner delay to 100ms, the laser path filling spacing to 1μm, and place the sample to be processed at the laser focal plane. A circular surface texture with a texture rate of 18%, a texture depth of 30μm, and a diameter of 200μm was processed, and after polishing, the following was obtained: Figure 2 The surface texture is shown. It can be seen that the circular texture is relatively regular, the recast layer around the texture has been removed, and the surface burrs have no obvious traces after polishing.

[0045] (4) 0.4 g of lecithin was weighed using an analytical balance and added to 100 ml of distilled water under stirring. After continuous stirring for 10 min, 0.35 g of sodium dodecylbenzenesulfonate was added. After stirring for 10 min, ultrasonic dispersion was performed for 4 min to obtain the following: Figure 3The nanoemulsion shown in the figure has spherical nanoparticles with a particle size ranging from 500 to 700 nm.

[0046] (5) The titanium alloy sample with surface texture treatment was used as the positive electrode, and the graphite was fixed as the negative electrode in the electrophoresis pool so that the distance was 4 cm. The lecithin emulsion was used as the electrophoresis liquid. Four electrophoresis cycles were performed, with voltages of 5 V, 10 V, 15 V, and 20 V applied respectively. The electrophoresis time was set to 10 min each time, forming a TC4 alloy surface filled with a lubricating medium. Figure 4 As shown, there are obvious particle depositions inside the texture, and these particles will play a lubricating role during the friction process.

[0047] Using ultra-high molecular polyethylene as the friction pair, a reciprocating pin-on-disk test was conducted on a UMT-2 friction and wear testing machine with a test load of 25N and a test frequency of 2Hz. Using simulated body fluid as the lubricant, the friction coefficient curves of the electrophoresis disc surface at different voltages were obtained as shown below. Figure 5 As shown in the figure, as the voltage increases, the overall friction curve first rises and then falls. The electrophoretic disk surface friction coefficient is the lowest under the action of a voltage of 15V, which has the best friction reduction effect.

[0048] Example 2

[0049] (1) Grind the titanium alloy surface with #400, #800, and #1200 sandpaper in turn, and polish it.

[0050] (2) Rinse with deionized water to remove the surface polishing liquid, and ultrasonicate in anhydrous ethanol solution for 10 minutes.

[0051] (3) Adjust the fiber laser power to 18W, the speed to 500mm / s, the on-delay to -150ms, the off-delay to 300ms, the corner delay to 100ms, the laser path filling spacing to 1μm, and place the sample to be processed at the laser focal plane. A circular surface texture with a texture rate of 18%, a texture depth of 30μm, and a diameter of 200μm was produced.

[0052] (4) Using an analytical balance, 0.3 g of lecithin was weighed and added to 100 ml of distilled water under stirring. After continuous stirring for 10 min, 0.2 g of sodium dodecylbenzenesulfonate was added. After stirring for 10 min, ultrasonic dispersion was performed for 4 min to obtain a nanoemulsion.

[0053] (5) The titanium alloy sample with surface texture treatment was used as the positive electrode, and the graphite was used as the negative electrode and fixed in the electrophoresis pool with a distance of 6 cm. Lecithin emulsion was used as the electrophoresis liquid. Voltages of 10 V, 15 V, and 20 V were applied respectively, and the electrophoresis time was set to 15 min.

[0054] Example 3

[0055] (1) Grind the titanium alloy surface with #400, #800, and #1200 sandpaper in turn, and polish it.

[0056] (2) Rinse with deionized water to remove the surface polishing liquid, and ultrasonicate in anhydrous ethanol solution for 10 minutes.

[0057] (3) Adjust the fiber laser power to 18W, the speed to 500mm / s, the on-delay to -150ms, the off-delay to 300ms, the corner delay to 100ms, the laser path filling spacing to 1μm, and place the sample to be processed at the laser focal plane. A circular surface texture with a texture rate of 18%, a texture depth of 30μm, and a diameter of 200μm was produced.

[0058] (4) Using an analytical balance, 0.1 g of lecithin was weighed and added to 100 ml of distilled water under stirring. After continuous stirring for 10 min, 0.1 g of sodium dodecylbenzenesulfonate was added. After stirring for 10 min, ultrasonic dispersion was performed for 4 min to obtain a nanoemulsion.

[0059] (5) The titanium alloy sample with surface texture treatment was used as the positive electrode, and the graphite was used as the negative electrode and fixed in the electrophoresis pool with a distance of 3 cm. Lecithin emulsion was used as the electrophoresis liquid. Voltages of 10 V, 15 V, and 20 V were applied respectively, and the electrophoresis time was set to 5 min.

[0060] Example 4

[0061] (1) Grind the titanium alloy surface with #400, #800, and #1200 sandpaper in turn, and polish it.

[0062] (2) Rinse with deionized water to remove the surface polishing liquid, and ultrasonicate in anhydrous ethanol solution for 10 minutes.

[0063] (3) Adjust the fiber laser power to 18W, the speed to 500mm / s, the on-delay to -150ms, the off-delay to 300ms, the corner delay to 100ms, the laser path filling spacing to 1μm, and place the sample to be processed at the laser focal plane. A circular surface texture with a texture rate of 18%, a texture depth of 30μm, and a diameter of 200μm was produced.

[0064] (4) Using an analytical balance, 0.2 g of lecithin was weighed and added to 100 ml of distilled water under stirring. After continuous stirring for 10 min, 0.15 g of sodium dodecylbenzenesulfonate was added. After stirring for 10 min, ultrasonic dispersion was performed for 4 min to obtain a nanoemulsion.

[0065] (5) The titanium alloy sample with surface texture treatment was used as the positive electrode, and the graphite was used as the negative electrode and fixed in the electrophoresis pool with a distance of 4 cm. Lecithin emulsion was used as the electrophoresis liquid. Voltages of 10 V, 15 V, and 20 V were applied respectively, and the electrophoresis time was set to 7 min.

[0066] Example 5

[0067] (1) Grind the titanium alloy surface with #400, #800, and #1200 sandpaper in turn, and polish it.

[0068] (2) Rinse with deionized water to remove the surface polishing liquid, and ultrasonicate in anhydrous ethanol solution for 10 minutes.

[0069] (3) Adjust the fiber laser power to 18W, the speed to 500mm / s, the on-delay to -150ms, the off-delay to 300ms, the corner delay to 100ms, the laser path filling spacing to 1μm, and place the sample to be processed at the laser focal plane. A circular surface texture with a texture rate of 18%, a texture depth of 30μm, and a diameter of 200μm was produced.

[0070] (4) Using an analytical balance, 0.25 g of lecithin was weighed and added to 100 ml of distilled water under stirring. After continuous stirring for 10 min, 0.2 g of sodium dodecylbenzenesulfonate was added. After stirring for 10 min, ultrasonic dispersion was performed for 4 min to obtain a nanoemulsion.

[0071] (5) The titanium alloy sample with surface texture treatment was used as the positive electrode, and the graphite was used as the negative electrode and fixed in the electrophoresis pool with a distance of 5 cm. Lecithin emulsion was used as the electrophoresis liquid. Voltages of 10 V, 15 V, and 20 V were applied respectively, and the electrophoresis time was set to 12 min.

[0072] Example 6

[0073] (1) Grind the titanium alloy surface with #400, #800, and #1200 sandpaper in turn, and polish it.

[0074] (2) Rinse with deionized water to remove the surface polishing liquid, and ultrasonicate in anhydrous ethanol solution for 10 minutes.

[0075] (3) Adjust the fiber laser power to 18W, the speed to 500mm / s, the on-delay to -150ms, the off-delay to 300ms, the corner delay to 100ms, the laser path filling spacing to 1μm, and place the sample to be processed at the laser focal plane. A circular surface texture with a texture rate of 18%, a texture depth of 30μm, and a diameter of 200μm was produced.

[0076] (4) Using an analytical balance, 0.35 g of lecithin was weighed and added to 100 ml of distilled water under stirring. After continuous stirring for 10 min, 0.25 g of sodium dodecylbenzenesulfonate was added. After stirring for 10 min, ultrasonic dispersion was performed for 4 min to obtain a nanoemulsion.

[0077] (5) Take the titanium alloy sample treated with surface texture as the positive electrode, and graphite as the negative electrode. Fix them in the electrophoresis cell with a distance of 6 cm. Use the lecithin emulsion as the electrophoresis solution, and apply voltages of 10 V, 15 V, and 20 V respectively. Set the electrophoresis time to 10 min.

[0078] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a medical TC4 titanium alloy with a lubricating medium filled in its surface texture, characterized in that, The following steps are involved: S1. Preparation of surface texture on TC4 alloy surface; In S1, surface texture was prepared by nanosecond laser; The laser wavelength of the nanolaser is 1064 nm, the laser power is 1~30 W, the light-on delay is -150 ms, the light-off delay is 300 ms, the corner delay is 100 ms, the pulse width is 100 ns, the laser spot diameter is 20 μm, the laser scanning speed is 500 mm / s, the laser processing frequency is 20 kHz, and the path filling spacing is 1 μm; S2, using the TC4 alloy with surface texture as the positive electrode, graphite as the negative electrode, and lecithin nanoemulsion as the electrophoresis liquid, to obtain a medical TC4 titanium alloy with surface texture filled with a lubricating medium after electrophoresis; Sodium dodecylbenzenesulfonate is added into the lecithin nanoemulsion.

2. The preparation method of a medical TC4 titanium alloy with a lubricating medium filled in a surface texture according to claim 1, characterized in that, In S1, the TC4 alloy was ground and polished to a roughness less than Ra0.02 μm.

3. The preparation method of a medical TC4 titanium alloy with a lubricating medium filled in the surface texture according to claim 1, characterized in that, The surface texture rate in S1 is 18%, the texture diameter is 200 μm, and the depth is 30 μm.

4. The preparation method of a medical TC4 titanium alloy with a lubricating medium filled in the surface texture according to claim 1, characterized in that, In S2, the distance between the positive and negative electrodes during electrophoresis was 3–6 cm.

5. The preparation method of a medical TC4 titanium alloy with a lubricating medium filled in the surface texture according to claim 1, characterized in that, In S2, the electrophoresis voltage was 5-20 V and the electrophoresis time was 5-10 min.

6. The preparation method of a medical TC4 titanium alloy with a lubricating medium filled in the surface texture according to claim 1, characterized in that, The concentration of lecithin nanoemulsion was 0.1~0.4 wt%.

7. A medical TC4 titanium alloy with a lubricating medium filled in the surface texture prepared by the preparation method according to any one of claims 1-6, characterized in that, The surface of the TC4 alloy is provided with a surface texture, and the surface texture is filled with a lubricating medium, and the lubricating medium is lecithin particles wrapped by sodium dodecylbenzene sulfonate.

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