Surface treatment method of titanium-tantalum alloy, application and titanium-tantalum alloy

Abstract

The application belongs to the technical field of metal surface treatment, and particularly relates to a surface treatment method of titanium-tantalum alloy, application and titanium-tantalum alloy. The method comprises the following steps: pretreating the surface of the titanium-tantalum alloy, and performing surface nanocrystallization treatment on the surface of the titanium-tantalum alloy after the pretreatment; the surface nanocrystallization treatment comprises mechanical grinding and / or ball milling and / or shot blasting. The application can realize the surface treatment of the titanium-tantalum alloy through a simple and efficient process, forms a micro-nano composite gradient layer structure on the surface of the titanium-tantalum alloy, realizes the mechanical property strengthening and surface functional modification of the titanium-tantalum alloy through the layer structure, significantly improves the antibacterial adhesion performance of the surface of the titanium-tantalum alloy, and can be more effectively used as a human implant device material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal surface treatment, and particularly relates to a surface treatment method of a titanium-tantalum alloy, application and titanium-tantalum alloy. BACKGROUND

[0002] Titanium alloy is considered as an ideal material for surgical implants due to its excellent biocompatibility and excellent processing performance, and has appeared many milestone applications in high-end metal instrument products. Among them, titanium-tantalum alloy, as one of the representatives of new medical titanium alloy, has good biocompatibility and corrosion resistance,

[0003] However, due to the mismatch of the strong plasticity of titanium-tantalum alloy, the mechanical properties thereof cannot meet the use standard, and the titanium-tantalum alloy cannot work smoothly under the influence of various cyclic loads, thereby limiting the biomedical application thereof. In addition, after the titanium-tantalum alloy is implanted into the human body, bacteria and other microorganisms are easily adhered to the surface of the titanium-tantalum alloy. After the bacteria are adhered to the surface of the material, the bacteria begin to proliferate, and finally reach a high enough density to form a biofilm infection. Once the infection occurs, it may cause local tissue damage and implant failure, and may also cause serious diseases and complications. Therefore, it is necessary to seek an efficient surface treatment method to improve the mechanical properties of the titanium-tantalum heterogeneous structure alloy and limit the initial adhesion of bacteria.

[0004] In recent years, researchers have developed surface nanocrystallization technology, that is, using a specific method to gradually refine the coarse crystal structure of the material surface to a nano-layer structure with a certain thickness, and the substrate part still maintains the original coarse crystal structure. After surface nanocrystallization, there is a "synergistic strengthening" effect between the gradient structure layer and the coarse crystal substrate layer. In addition, the coordinated deformation between the gradient structure layers during stretching can effectively inhibit the strain concentration and early necking caused by the deformation of the surface nanocrystalline grains, thereby delaying the deformation localization and crack initiation of the surface nanocrystalline structure, and thus the material can exhibit good tensile properties. Nanocrystalline can increase the specific surface area, micro-roughness and wettability, thereby enhancing the biological activity of the material. In addition, the nano-structured surface has higher surface energy and can exhibit better hydrophilicity, which can quickly bind water molecules near the surface of the titanium-tantalum heterogeneous structure alloy to form a hydration layer, thereby blocking the mutual contact between bacteria and the surface, thereby reducing bacterial adhesion.

[0005] However, these methods also have some problems, such as being unable to process parts with large size or complex shape, expensive equipment, complex process, etc. Therefore, it is necessary to develop a method which is simple in process and can realize surface nanocrystallization of parts with complex shape or large size to promote the application of nanocrystallization process in actual production. SUMMARY

[0006] In order to solve the problems of the existing surface nanocrystallization treatment method, such as complex process, difficult processing, expensive equipment, and inability to treat parts with complex shape, the present application provides a surface treatment method of titanium-tantalum alloy, application thereof, and titanium-tantalum alloy prepared by the method.

[0007] The present application aims at:

[0008] I. The nanocrystallization of the surface of titanium-tantalum alloy can be realized by a low-cost, simple and easy method.

[0009] II. It can be applied to the treatment of parts with complex shape.

[0010] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions.

[0011] A surface treatment method of titanium-tantalum alloy,

[0012] The method comprises:

[0013] The surface of the titanium-tantalum alloy is pretreated, and the surface nanocrystallization treatment is performed on the surface of the titanium-tantalum alloy after pretreatment.

[0014] The surface nanocrystallization treatment comprises mechanical milling and / or ball milling and / or shot blasting.

[0015] For the present application, the mechanical properties and the antibacterial adhesion properties of titanium-tantalum alloy can be effectively improved by a simple and efficient mechanical treatment method. It mainly includes two processes. The first process is pretreatment. In the pretreatment process, the crystal structure of the surface of the titanium-tantalum alloy is improved and adjusted, and it has the basis for further nanocrystallization treatment. The second process is the nanocrystallization treatment based on the results of the pretreatment. For different pretreatment results, the present application provides three different nanocrystallization treatment methods.

[0016] As a preferred,

[0017] The titanium-tantalum alloy is a titanium-tantalum heterogeneous structure alloy.

[0018] The homogeneous structure alloy and the heterogeneous structure alloy of titanium-tantalum alloy have certain differences in mechanical properties. For example, the grain structure is different. The homogeneous structure has smaller spacing and higher L-C lock (Lomer-Cottrell lock) density between each nanoscale layer structure, which leads to better tensile ductility, prevents dislocation slip and dislocation accumulation. While the heterogeneous material alloy is more prone to defects, which makes the grain more prone to fragmentation and refinement, and realizes dislocation accumulation. For the present application, dislocation accumulation and grain refinement are obviously the key factors to improve the treatment effect. Therefore, for the present application, the titanium-tantalum heterogeneous structure alloy has obviously better use effect.

[0019] As preferred,

[0020] The pre-treatment comprises grinding and / or polishing and / or ultrasonic cleaning, and at least grinding treatment.

[0021] For the technical solution of the present application, grinding treatment is an indispensable process. Under normal conditions, the titanium-tantalum heterogeneous structure alloy surface after rolling treatment and wire cutting has a relatively thick oxide layer, which has an impact on the mechanical properties of the titanium-tantalum alloy. Therefore, in the technical solution of the present application, by grinding the titanium-tantalum heterogeneous structure alloy, the oxide layer can be removed to a certain extent, which is beneficial to the subsequent surface nanocrystallization treatment.

[0022] As preferred, the grinding is performed at least four times, and the grinding mesh increases with the grinding process, the difference between the mesh of adjacent two grindings is ≥200 mesh, and the mesh of the last grinding is 1100-1300 mesh.

[0023] For the technical solution of the present application, the grinding process needs to be strictly controlled. Especially for the control of the grinding mesh, the most important thing is to ensure that the mesh of the last grinding should be between 1100-1300 mesh. If the mesh is too small, it cannot effectively realize sub-micronization or micro-nanocrystallization, and cannot effectively utilize the advantages of the heterogeneous structure titanium-tantalum alloy. If the mesh is too large, due to the characteristics of the heterogeneous structure titanium-tantalum alloy itself, it is easy to cause the loss of micron grains and micro-nanocrystalline grains formed by grinding, and the retention rate is low. Controlling the number of grindings and the difference between the meshes of adjacent grindings is to improve the stability of the micron grains and micro-nanocrystalline grains formed.

[0024] As preferred, in the mechanical grinding process, the control pass amount is 25-100 μm, the grinding pass is 3-5 times, the total pass amount is 100-400 μm, and the grinding head feeding rate is 60-120 mm / min.

[0025] Mechanical grinding is essentially different from conventional mechanical grinding. Mechanical grinding mainly plays a role in refining grains, while the mechanical grinding of the present application fixes the substrate material to the numerical control machine tool with grinding tooling, selects the amount of pressure of the grinding head according to the strength and thickness of the substrate material, and the numerical control machine tool drives the grinding head to perform surface grinding treatment on the titanium alloy plate with a preset amount of pressure, thereby generating a deep residual compressive stress layer and a hardening layer on the metal surface.

[0026] Combined with the grinding process described above, the nanocrystalline layer can be further refined, and the thickness of the nanocrystalline layer can be increased.

[0027] Preferably, the ball milling is carried out in a protective atmosphere, the ball-to-charge ratio is controlled to be (4-5):1, the diameter of the milling ball is 5-10 mm, the rotation speed of the ball mill is 400-600 r / min, and the ball milling time is 12-24 h.

[0028] The ball milling of the application is not a conventional crushing ball milling, but a new type of finishing ball milling and polishing technology.

[0029] Preferably, the diameter of the shot is 0.3-2.0 mm, the shot time is 15-60 min, and the shot speed is 30-60 m / s.

[0030] The shot is a relatively common surface treatment method. During the shot treatment, the shot media densely act on the surface of the substrate, forming a continuous impact effect, so that the grains on the surface of the titanium-tantalum alloy are continuously refined and fragmented. The micro-nano grains formed during the polishing process further intensify the process, and a nanocrystalline layer with a larger thickness than that formed by mechanical milling is formed on the surface of the titanium-tantalum alloy.

[0031] A surface treatment method of a titanium-tantalum alloy and an application thereof,

[0032] The method is used to improve the mechanical properties and antibacterial adhesion properties of the titanium-tantalum alloy.

[0033] After being treated by the method, the mechanical properties and antibacterial adhesion properties of the titanium-tantalum alloy can be significantly improved.

[0034] A titanium-tantalum alloy,

[0035] The titanium-tantalum alloy comprises, from the surface to the inside, a nanocrystalline layer, a transition layer, and a substrate layer.

[0036] The nanocrystalline layer and the transition layer on the surface of the titanium-tantalum alloy form a gradient structure layer, producing a synergistic strengthening effect. At the same time, coordinated deformation is formed between the gradient structure organizations during the stretching process, inhibiting the strain concentration or early necking process on the surface of the titanium-tantalum alloy. Meanwhile, the surface energy of the surface of the titanium-tantalum alloy is improved, the hydrophilicity is enhanced, the titanium-tantalum alloy surface can quickly combine water molecules to form a hydration layer, thereby reducing bacterial adhesion.

[0037] The beneficial effects of the present application are:

[0038] The present application can realize the surface treatment of titanium-tantalum alloy through a simple and efficient process, form a composite gradient layer structure on the surface of the titanium-tantalum alloy, realize the mechanical property strengthening and surface functional modification of the titanium-tantalum alloy through the layer structure, and significantly improve the antibacterial adhesion performance of the titanium-tantalum alloy surface, so that the titanium-tantalum alloy can be more effectively used as a human implant device material. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a schematic diagram of a plate-shaped sample;

[0040] Figure 2 It is a schematic diagram of a grinding track and a grinding head;

[0041] Figure 3 It is the XRD characterization result of the sample of Example 1;

[0042] Figure 4 It is the SEM characterization result of the sample of Example 1;

[0043] Figure 5 It is the TEM characterization result of the sample with a 100 μm pass amount of downward pressure in Example 1;

[0044] Figure 6 It is the tensile strength characterization result of the sample of Example 1;

[0045] Figure 7 It is a diagram of the adhesion of Staphylococcus aureus on the surface of the sample under a fluorescence microscope in Example 1. DETAILED DESCRIPTION

[0046] The present application will be further described and illustrated in detail in the following in combination with specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present application based on these descriptions. In addition, the embodiments of the present application involved in the following descriptions are generally only a part of the embodiments of the present application, but not all the embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments in the present application without making creative efforts shall belong to the scope of protection of the present application.

[0047] Unless otherwise specified, the raw materials used in the embodiments of the present application are commercially available or can be obtained by those skilled in the art; unless otherwise specified, the methods used in the embodiments of the present application are the methods mastered by those skilled in the art.

[0048] Unless otherwise specified, the titanium-tantalum alloy used in the present application is prepared as Figure 1The plate-shaped specimen shown has a gauge length of 19.75 mm, a width of 7 mm, and a thickness of 3 mm.

[0049] Example 1

[0050] A surface treatment method for titanium-tantalum alloy,

[0051] The specific method is as follows:

[0052] The titanium-tantalum alloy surface, after the oxide layer has been removed and the surface has been cleaned, is then polished.

[0053] The polishing process is carried out sequentially using 400 grit, 600 grit, 800 grit and 1200 grit sandpaper, with mechanical polishing in the same direction 100 times, without changing the sandpaper during the polishing process;

[0054] After the grinding process, the titanium-tantalum alloy was subjected to conventional mechanical polishing at a speed of 1000 r / min. The polishing cloth was made of synthetic leather polymer material with an abrasive particle size of W 0.5 and a polishing time of 5 min. Then, it was placed in acetone for ultrasonic cleaning for 20 min to complete the pretreatment and serve as the substrate.

[0055] The pretreated titanium-tantalum alloy was subjected to mechanical grinding for surface nano-sizing treatment:

[0056] The substrate is fixed to the CNC machine tool equipped with a grinding fixture. The CNC machine tool drives the grinding head to perform surface grinding on the titanium alloy plate using a preset pressure, generating a deep residual compressive stress layer and a hardened layer on the metal surface. Specifically, during the mechanical grinding process: the grinding head is a conventional bullet-shaped grinding head; the grinding medium is WC / Co with a diameter of 14.35 mm; the row spacing of the grinding head is 0.5 mm; the pressure per pass is 25 μm-100 μm; the grinding passes are 4 times; the total pressure is 100 μm-400 μm; and the grinding head feed rate is 60 mm·min. -1 The grinding trajectory is cyclical, and the macroscopic view of the grinding head and the schematic diagram of the grinding trajectory are as follows: Figure 2 As shown.

[0057] Specifically, three experimental groups were set up with pass compression amounts of 25 μm, 50 μm, and 100 μm, respectively, and a blank control group (original, without mechanical milling surface nano-treatment) was set up. The total compression amounts of the three experimental groups were 100 μm, 200 μm, and 400 μm, respectively.

[0058] The samples prepared from the three experimental groups and the blank control group were characterized by XRD. The characterization results are as follows: Figure 3 As shown. From Figure 3The characterization results clearly show that the grain structure of the obtained sample products differs significantly under different pass pressure treatments. Simultaneous SEM and TEM characterization were performed, and partial SEM characterization results for each group of samples are shown below. Figure 4 As shown, Figure 4 The indentation depths for each pass, from left to right, are 25 μm, 50 μm, and 100 μm, respectively. The characterization results for the sample with an indentation depth of 100 μm are as follows: Figure 5 As shown. From Figure 4 SEM characterization results and Figure 5 The TEM characterization results clearly show that as the pressure decreases, the thickness of the nanocrystalline layer on the surface increases from 1 μm to 9 μm, which is positively correlated with the pressure decrease. At the same time, SEM and TEM characterization revealed that a transition layer with a thickness of 30–90 μm was formed during this process, and the thickness of the transition layer was also positively correlated with the pressure decrease. The size of the grains in the nanocrystalline layer was 10–20 nm. However, it was found that the grain size was not negatively correlated with the pressure decrease per pass as expected. That is, the smallest grain size was found in the experimental group sample with a pressure decrease of 50 μm per pass. This shows that a larger pressure decrease per pass is not necessarily better.

[0059] In addition, tensile strength tests were performed on the three experimental groups and the blank control group. Room temperature tensile tests and cyclic loading / unloading tests on the plate samples were conducted on an INSTRON 5982 universal testing machine at a tensile rate of 1 mm / min. The test results are as follows: Figure 6 As shown. From Figure 6 The characterization test results show that the tensile strength of the plate-shaped sample continuously increases with the increase of the compression depth per pass. When the compression depth per pass is 25 μm, the tensile strength increases from approximately 820 MPa to approximately 900 MPa, which is a very significant improvement. When the compression depth per pass reaches 100 μm, the tensile strength can even reach 1100 MPa. This demonstrates that the process of the present invention has a significant strengthening and improving effect on the mechanical properties of titanium-tantalum alloys.

[0060] Furthermore, from Figure 6 It can also be clearly seen that as the compression of each pass increases, the elongation at break gradually decreases. When the compression of each pass is 25 μm and 50 μm, the tensile strength and elongation at break are significantly better than the original control group. However, the elongation at break of the experimental group with a compression of 100 μm is lower than that of the original control group. It can also be seen from the figure that as the compression of each pass increases, the end of the tensile curve gradually becomes flat, and its brittleness increases significantly. Therefore, it is necessary to reasonably control the compression of each pass. Therefore, the following experiment was conducted.

[0061] The pass down pressure was adjusted to 20 μm and 110 μm, respectively, and the rest of the parameters were the same as the above-mentioned test group, which was used as a test control group, and the above-mentioned characterization and testing were also carried out. The test results showed that when the pass down pressure was 20 μm, the tensile strength of the plate-shaped sample was almost not increased compared with the original control group, and was about 835 MPa. When the pass down pressure was 110 μm, the plate-shaped sample was brittlely fractured at about 900 MPa, and the SEM characterization results showed that the nanocrystalline layer thickness increased to about 10 μm but the transition layer thickness decreased sharply, which destroyed the multi-layer gradient layer structure and led to a significant decrease in mechanical properties. It can be seen that in the selection of pass down pressure, 25-100 μm should be selected to ensure that it has a relatively optimal strengthening effect.

[0062] In addition, comparative tests were carried out on the down pressure pass, and the test group with a pass down pressure of 50 μm was used as the basis, and the pass was changed to 2, 3, 5, 6, and 8 times. When the pass was 2 times, the nanocrystalline layer thickness was relatively thick compared with the original 25 μm pass down pressure (4 passes), but the transition layer was thin, and the mechanical property characterization showed that the elongation at break was significantly decreased and lower than the original control group, and the tensile strength also did not produce a significant improvement effect. When the rolling pass was 3 and 5 times, the mechanical properties were relatively close to the 4-pass test group, and as the rolling pass further increased, to 6 times, the plate-shaped sample gradually began to produce obvious brittleness, and the elongation at break began to decrease significantly. When the rolling pass was 8 times, the elongation at break was close to the 100 μm pass down pressure, 4-pass test group, but the tensile strength was only about 960 MPa, and the actual effect was not good, so controlling the rolling pass to 3-5 times can ensure a relatively optimal strengthening result.

[0063] In addition, the feed rate of the grinding head also has a significant influence on the mechanical properties of the sample. In the case of controlling the pass under-pressing amount to be 50 μm and the rolling pass to be 4 passes, the feed rate of the grinding head is controlled to be 20 mm / min, 40 mm / min, 60 mm / min, 80 mm / min, 100 mm / min, 120 mm / min and 140 mm / min, respectively. With the increase of the feed rate of the grinding head, the elongation at break of the plate-shaped sample is increased, and the elongation at break is positively correlated with the feed rate of the grinding head during 20-80 mm / min. In the 20-40 mm / min test group, the elongation at break is slightly smaller than that of the original control group, and it increases explosively to 8.1% from 7.6% of the original control group at 60 mm / min. During 100-120 mm / min, the elongation at break gradually decreases, and the elongation at break at 120 mm / min is similar to that of the 60 mm / min test group. The tensile strength basically shows a gradual downward trend with the increase of the feed rate of the grinding head. In order to ensure good strengthening effect of the material, the feed rate of the grinding head is selected to be 60-120 mm / min, which is a relatively optimal choice.

[0064] On the basis of the above test, the commercially available titanium-tantalum homogeneous structure alloy is selected to prepare the same plate-shaped sample, and the same processing as the 50 μm pass under-pressing amount and 4 pass test group is carried out. The blank control is also set, and compared with the blank control, the elongation at break of the sample is decreased by about 0.6%, and the tensile strength is increased by only about 1.2%. It can be seen that the effect of the present application is significantly different for homogeneous structure alloy and heterogeneous structure alloy, and the processing mode of the present application is more suitable for heterogeneous structure alloy.

[0065] In addition, the anti-bacterial adhesion performance test is carried out on each test group (the pass under-pressing amount is 25 μm, 50 μm and 100 μm, and the rolling pass is 4 passes) and the original control group. Specifically, Staphylococcus aureus (S. aurues) is selected as the test object, and after cultivation, the terminal single colony is inoculated into Luria-Bertani (LB) liquid medium, and incubated at 37°C in a shaking incubator for 12 h at a speed of 180 rpm. The surface-treated substrate material is subjected to live and dead bacteria staining test, and the number distribution of live and dead bacteria is observed under a fluorescence inverted microscope at 40 times magnification and 20 μm.

[0066] Among them:

[0067] The culture process of Staphylococcus aureus is specifically as follows: the bacterial strain is coated on the surface of solid culture medium, sealed, and then inverted and incubated at 37°C for overnight, and then a proper amount of the concentrated bacterial liquid after culture is dropped into new LB liquid culture medium and diluted to a proper concentration (ODS≈0.05 at 600 nm wavelength) before subsequent testing;

[0068] The test of live and dead bacteria staining is specifically as follows: the base material is placed in a petri dish, soaked with 75wt% ethanol for 10 min, PBS for 10 min, and sterilized and disinfected by ultraviolet lamp irradiation for 10 min, and then placed in a 12-well plate, 3ml of diluted LB liquid culture medium is injected into each well, and placed in a 37°C shaking incubator for incubation for 12h at a speed of 120rpm, then the sample surface is washed with PBS solution to remove the bacteria not adhered to the sample surface, the paper towel is used to absorb the excess PBS solution, the sample is placed on a glass slide with the front face upward, and 10μL of diluted Live / Dead BackLight kit staining agent is dropped on the sample surface to stain the bacteria, and after staining for 10 min, the excess staining agent is washed away with PBS solution, and the sample is inverted on the glass slide.

[0069] In the above test, the results of the original control group and the 100μm test group are represented by the comparison graph as shown in Figure 7 From the graph, it can be seen that after the titanium-tantalum alloy is treated by the process of the application, the bacterial adhesion rate is obviously reduced. The bacterial adhesion rate of the 25μm pass amount test group is 18.1% of that of the original control group, the bacterial adhesion rate of the 50μm pass amount test group is 12.9% of that of the original control group, and the bacterial adhesion rate of the 100μm pass amount test group is 16.6% of that of the original control group, so the titanium-tantalum alloy surface treated by the process of the application has very excellent antibacterial adhesion performance.

[0070] Example 2

[0071] A surface treatment method of a titanium-tantalum alloy,

[0072] The specific method is as follows:

[0073] The titanium-tantalum alloy surface after removing the oxide layer and cleaning is polished:

[0074] The polishing process is performed in sequence with 400 mesh, 600 mesh, 800 mesh and 1200 mesh sandpaper, and the sandpaper is not replaced during the polishing process.

[0075] After the polishing treatment, the titanium-tantalum alloy is subjected to conventional mechanical polishing treatment at a polishing speed of 1000 r / min, using synthetic leather high molecular material as polishing cloth, abrasive particle size of W 0.5, and polishing time of 5 min, and then is subjected to ultrasonic cleaning in acetone for 20 min to complete the pretreatment as a base material.

[0076] The titanium-tantalum alloy subjected to the pretreatment is subjected to ball milling polishing surface nanocrystallization treatment:

[0077] The ball milling is performed on a Haas CNC vertical machining center VF-3, the base material and the milling ball are assembled, then vacuum is extracted to control the vacuum degree < 10 Pa, then argon is filled, and the ball milling is performed under argon protection, the ball-to-material ratio is controlled to be 4:1, the milling ball is made of stainless steel, the diameter of the milling ball is 6 mm, the ball milling speed is 300-700 r / min (with an interval of 100 r / min, a total of 5 test groups), and the ball milling time is 18 h. A test group without ball milling polishing is set as an original control group.

[0078] The samples prepared in the five test groups and the original control group are also subjected to XRD characterization, and the characterization shows that the grain structures of the products obtained in the test groups at different ball milling speeds are obviously different. Meanwhile, SEM characterization and TEM characterization are performed, and the characterization results show that with the increase of the ball milling polishing speed, the thickness of the nanocrystalline layer on the surface first increases and then decreases, the thickness of the nanocrystalline layer is less than 0.5 μm when the ball milling polishing speed is 300 r / min and 700 r / min, and the thickness of the nanocrystalline layer is 0.8-3 μm between 400 r / min and 600 r / min. Meanwhile, it is found in the SEM characterization and the TEM characterization that a transition layer with a thickness of 50-110 μm is formed in the process, and the thickness of the transition layer first increases and then decreases with the increase of the ball milling polishing speed.

[0079] In addition, the tensile strength and the antibacterial adhesion performance of the five test groups and the original control group are detected, and compared with the original control group. The comparison results are as follows.

[0080] Ball milling rotation speed Relative change rate of tensile strength Relative change rate of elongation at break Relative change rate of bacterial adhesion rate Original control group / / / 300 r / min -1.1％ +5.7％ -90.1％ 400 r / min +1.1％ +7.3％ -89.9％ 500 r / min +3.2％ +8.6％ -92.0％ 600 r / min +2.0％ +6.2％ -91.9％ 700 r / min +0.1％ +6.6％ -73.3％

[0081] In the table, "+" indicates an increase, "-" indicates a decrease, and the relative change rate Re is calculated as follows:

[0082]

[0083] Wherein Cv1 is the test group characterization value, Cv0 is the original control group characterization value, Cv1 and Cv0 are the same characterization values, and are the tensile strength, the elongation at break or the bacterial adhesion rate.

[0084] From the above characterization results, it can be seen that the ball milling speed has a relatively significant influence on the mechanical properties and bacterial adhesion resistance of the treated samples. The relatively optimal treatment result can be obtained by selecting a ball milling speed of 400-600 r / min.

[0085] In addition, the ball milling speed was controlled at 500 r / min, and only the ball milling time was changed for comparative tests. The ball milling time was 6 h, 12 h, 24 h, and 30 h, respectively. The treated sample specimens were characterized and compared with the original 18 h test group. The comparative test results show that as the ball milling time is prolonged, the mechanical properties of the titanium-tantalum alloy gradually increase, the bacterial adhesion resistance increases first and then decreases, but the antibacterial performance is significantly better than that of the original control group. However, when the ball milling time is only 6 h, the mechanical properties do not significantly increase compared with the original control group. Therefore, the ball milling time should be controlled to be ≥12 h, and in order to ensure relatively optimal bacterial adhesion resistance, the ball milling time should be controlled to be 12-30 h.

[0086] Example 3

[0087] A surface treatment method of a titanium-tantalum alloy,

[0088] The specific method is as follows:

[0089] The surface of the titanium-tantalum alloy after removing the oxide layer and cleaning is polished:

[0090] The polishing process is performed in sequence using 400-mesh, 600-mesh, 800-mesh, and 1200-mesh sandpaper, and the sandpaper is not replaced during the polishing process.

[0091] After the polishing treatment, the titanium-tantalum alloy is subjected to conventional mechanical polishing treatment, the polishing speed is 1000 r / min, the polishing cloth is made of synthetic leather high molecular material, the abrasive particle size is W 0.5, and the polishing time is 5 min. Then, the titanium-tantalum alloy is placed in acetone for ultrasonic cleaning for 20 min, and the pretreatment is completed, serving as a base material.

[0092] The titanium-tantalum alloy after the pretreatment is subjected to shot blasting surface nanocrystallization treatment:

[0093] The shot blasting is to spray the projectile at high speed to the metal surface by means of high-pressure airflow to cause strong plastic deformation of the surface. In this embodiment, the shot blasting medium is stainless steel ball, the diameter of the shot blasting medium is 1.0 mm, the shot blasting time is 15-90 min (with an interval of 15 min, and a total of 6 test groups), and the shot blasting medium spraying speed is 45 m / s.

[0094] The XRD characterization was also performed on the samples prepared in the 6 test groups and the original control group, and the characterization showed that the grain structure of the products of the samples had obvious differences under the treatment of different ball milling speeds. The SEM characterization and the TEM characterization were also performed, and the characterization results showed that with the extension of the shot peening time, the thickness of the nanocrystalline layer on the surface first increased and then rapidly decreased, and the thickness of the nanocrystalline layer reached a maximum value when the shot peening time was 45 min, and the thickness of the nanocrystalline layer could reach 12 μm, and after the shot peening time reached 75 min, the thickness of the nanocrystalline layer rapidly decreased from 10.3 μm at 60 min to 3.2 μm, and the thickness of the nanocrystalline layer was about 6-12 μm within the shot peening time of 15-60 min, and it was found in the SEM characterization and the TEM characterization that a transition layer with a thickness of 20-60 μm was formed in the process, and the thickness of the transition layer gradually increased with the extension of the shot peening time.

[0095] In addition, the tensile strength and the antibacterial adhesion performance of the 6 test groups and the original control group were detected, and the original control group was compared. The comparison results are as follows.

[0096] Shot time Relative change rate of tensile strength Relative change rate of elongation at break Relative change rate of bacterial adhesion rate Original control group / / / 15 min +16.7％ +3.1％ -88.9％ 30 min +19.7％ +0.6％ -90.1％ 45 min +21.2％ -2.7％ -89.2％ 60 min +18.0％ -6.2％ -90.8％ 75 min +13.2％ -19.7％ -89.3％ 90 min +7.1％ -39.6％ -89.2％

[0097] In the table, "+" represents increase, "-" represents decrease, and the relative change rate Re is calculated by the following formula:

[0098]

[0099] Wherein Cv1 is the characterization value of the test group, Cv0 is the characterization value of the original control group, and Cv1 and Cv0 are the same characterization values, which are the tensile strength, the elongation at break or the bacterial adhesion rate.

[0100] From the above characterization results, it can be seen that with the extension of the shot peening time in the shot peening process, the elongation at break of the material obviously decreases, and becomes brittle at 75 min, and the tensile strength of the titanium-tantalum alloy also gradually decreases from 45 min, so for the technical scheme of the present application, the shot peening time should be controlled within 60 min, and the optimal should be 15-60 min.

[0101] From the above embodiments, it can be obviously seen that the present application can effectively strengthen the titanium-tantalum alloy by the simple and efficient two-step method. In terms of mechanical properties and antibacterial adhesion performance, the present application can produce obvious promotion effect. The prepared titanium-tantalum heterogeneous structure alloy has very excellent performance, and can be effectively used for the preparation of implantable medical devices.

Claims

1.A method for surface treatment of titanium-tantalum alloy, characterized in that, the method comprises: pre-treating the surface of the titanium-tantalum alloy, and then performing surface nanocrystallization treatment on the surface of the titanium-tantalum alloy after the pre-treatment; the surface nanocrystallization treatment comprises mechanical rolling and / or ball milling and / or shot peening; the titanium-tantalum alloy is a titanium-tantalum heterostructure alloy; the pre-treatment comprises grinding and / or polishing and / or ultrasonic cleaning, and at least grinding; the grinding is performed at least four times, and the grit size is increased with the progress of the grinding, the difference between the grit sizes of two adjacent times of grinding is greater than or equal to 200 mesh, and the grit size of the last time of grinding is 1100-1300 mesh; in the mechanical rolling, the pass amount is controlled to be 25-100 μm, the rolling pass is 3-5 times, the total pass amount is 100-400 μm, and the feed rate of the rolling head is 60-120 mm / min; the ball milling is performed in a protective atmosphere, the ball-to-material mass ratio is controlled to be (4-5) : 1, the diameter of the milling ball is 5-10 mm, the rotation speed of the milling ball is 400-600 r / min, and the ball milling time is 12-24 h; and after the surface nanocrystallization treatment, the titanium-tantalum alloy has, from the surface to the inside, a nanocrystalline layer, a transition layer and a matrix layer. 2.The method according to claim 1, characterized in that, the diameter of the shot peening medium is controlled to be 0.3-2.0 mm, the shot peening time is 15-60 min, and the shot peening speed of the shot peening medium is 30-60 m / s. 3.An application of the method according to any one of claims 1-2, characterized in that, the method is used to improve the mechanical properties and the anti-bacterial adhesion properties of the titanium-tantalum alloy. 4.A titanium-tantalum alloy treated by the method according to any one of claims 1-2, characterized in that, the titanium-tantalum alloy has, from the surface to the inside, a nanocrystalline layer, a transition layer and a matrix layer. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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