Pure titanium with surface topography and method for manufacturing the same

Abstract

The application provides pure titanium with a surface topological structure and a preparation method thereof, and belongs to the technical field of implant material preparation. The specific process is as follows: sequentially performing multi-pass rotary forging, heat treatment, mechanical grinding, annealing treatment, turning, polishing treatment and corrosion treatment on a pure titanium rod to obtain the pure titanium with the surface topological structure. The pure titanium rod obtained by the simple and mature process has high strength and toughness and excellent biocompatibility, can be widely used to replace titanium alloy in the field of medical implants, and the preparation process has the characteristics of low cost, short cycle, large product size, large scale and industrial production.

Description

Technical Field

[0001] This invention relates to the field of implant material preparation technology, and in particular to a pure titanium with a surface topology and its preparation method. Background Technology

[0002] Orthopedic diseases such as fractures and avascular necrosis of the femoral head, as well as dental diseases such as tooth loss, damage, and decay, often require orthopedic implants or dental implant surgeries. These implant surgeries are often accompanied by significant pain, lengthy recovery periods, and heavy financial burdens, presenting numerous clinical challenges. With an aging population and increasing life expectancy, the field of bio-implants holds immense economic potential, reflecting the exacerbation of these clinical challenges, which urgently require solutions. For the former, implant surgery is largely unavoidable, thus relying on advancements in clinical technology and medical conditions. For the latter two, shortening recovery periods and reducing costs can be improved through innovative implant materials and improved surface treatment techniques. Furthermore, high-performance implant materials can also eliminate the need for secondary surgeries, effectively preventing increased clinical pain and financial burden.

[0003] This necessitates that next-generation implant materials possess both excellent biocompatibility (non-toxic, good osteogenic properties) and long-term implantable mechanical properties (good strength and toughness, corrosion resistance). Among metallic materials, pure titanium has the lowest toxicity and best biocompatibility, significantly reducing the risks of implant rejection, allergies, and complications, thus contributing to successful implantation surgery and improved rehabilitation outcomes. It is the most promising bio-implant material. Compared to commonly used titanium alloys TC4 and third-generation β-type titanium alloys, pure titanium does not contain toxic elements such as Al and V, precious metal elements such as Nb and Ta, or rare earth metals, making it more suitable as a low-cost, long-term implant material. However, compared to the two types of titanium alloys mentioned above, conventional coarse-grained pure titanium has low strength and poor wear resistance, limiting its application as a load-bearing orthopedic implant. Therefore, designing and preparing high-strength and high-toughness pure titanium, achieving comprehensive mechanical parameters such as strength and ductility at the strength and toughness levels of TC4 and β-type titanium alloys, is key to enabling pure titanium to widely replace titanium alloys in the field of medical implants, and is one of the urgent problems that need to be solved.

[0004] After meeting the requirements of high strength and toughness, most metals (including pure titanium) still have problems such as bioinertness and weak antibacterial ability. Therefore, when directly implanted, they have problems such as poor hydrophilicity, poor cell adsorption capacity, and poor cell diffusion growth capacity, resulting in poor performance expression (such as osteogenic performance). A search of published patents and papers found that surface characteristics are crucial to the performance expression of implants. To solve the above problems, special treatment is generally performed on the surface of the implant. The most typical surface treatment methods are as follows: (1) Electrochemical anodic treatment. The patent application CN202511079323.9 states that a low-roughness, intact surface can be obtained through electrochemical anodic treatment. However, this process has the risk of potential pollution from electrolytic byproducts, which may affect the effectiveness of the drug delivery system and patient safety. (2) Sandblasting and acid etching: “Effect of bulk microstructure of commercially pure titanium on surface characteristics and fatigue properties after surface modification by sandblasting and acid-etching” can effectively improve the hydrophilicity and osseointegration performance of implants by sandblasting and acid etching. However, the sandblasting and acid etching process leaves sand particles or bulk particles, resulting in problems such as unsuitable pore size and large roughness. (3) Dopamine fixation: “Polydopamine Linking Substrate for AMPs: Characterisation and Stability on Ti6Al4V” fixes dopamine on the implant surface, making it exhibit significant biodegradability and excellent cell adhesion ability. However, the surface after dopamine fixation treatment leads to a significant reduction in deposition rate and “new bone-implant” bonding strength. (4) Layer-by-Layer Self-Assembly Strategies of Atomically Thin Two Dimensional Nanomaterials: Principles, Methods, and Functional Applications. Through the layer-by-layer self-assembly of the coating, the coating thickness on the implant surface can be precisely controlled. During assembly, a suitable coating, such as a flexible coating, can be selected according to the requirements.However, long-term implantation can lead to problems such as drug loss and decreased coating stability due to weak bonding strength.

[0005] Another promising surface treatment method is to process and prepare topological structures of specific shapes on the implant surface by means of laser etching, directional acid etching and other methods. Topological structures have the advantages of arbitrary shape and size change and non-detachment based on the bulk material. They can easily achieve the goals of improving surface hydrophilicity, enhancing cell adhesion and diffusion ability, and establishing drug delivery systems to locally release anti-inflammatory, antibacterial or osteoinducing drugs. It can be seen that topological structure optimization is another important advancement in implant surface treatment technology. Although artificially designed and prepared topological structures can exhibit good biocompatibility, there are the following problems when preparing artificial topological structures with micro-nano precision by means of laser etching and other methods: (1) The technical difficulty is extremely high. At present, advanced etching technology is monopolized by foreign countries; (2) Large-scale industrialization is difficult, especially for large orthopedic implants; (3) The production process is complicated, the processing cycle is long and the cost is high, which greatly increases the economic burden on patients.

[0006] The solution to these challenges lies in innovating the bulk material, enabling it to possess high strength and toughness, excellent biocompatibility, and customizable surface epitaxial growth topology, especially for bioimplants using pure titanium as the bulk material. However, no relevant reports have been published to date. Therefore, developing a pure titanium substrate with high strength and toughness, excellent biocompatibility, and customizable surface epitaxial growth topology, along with its preparation method, is of great significance. Summary of the Invention

[0007] The purpose of this invention is to provide a pure titanium with a surface topological structure and its preparation method, so as to solve the problems of high technical difficulty, high industrialization difficulty and high cost in the preparation of topological structures in implants in the prior art.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing pure titanium with a surface topological structure, comprising the following steps: sequentially subjecting a pure titanium rod to multi-pass rotary forging, heat treatment, mechanical grinding, annealing, turning, polishing and etching to obtain pure titanium with a surface topological structure.

[0009] Preferably, the strain of the multi-pass rotary forging is 1.2~3.5, the processing temperature is 20~300℃, and the diameter reduction of each pass of rotary forging is 0.5~2mm.

[0010] Preferably, the heat treatment is a single surface induction heat treatment, with a temperature of 400~475℃, a current of 15~80A, and a time of 2~30s.

[0011] Preferably, the temperature of the mechanical grinding is -196~20℃ and the speed is 2~40mm / s.

[0012] Preferably, the annealing process involves a heating rate of 3-5°C / min, a temperature of 300-500°C, and a holding time of 20-40 min; followed by a cooling process with a cooling rate of 5-7°C / min.

[0013] Preferably, the peeling thickness during turning is 0.5~4.5mm.

[0014] Preferably, the corrosion treatment uses Kroll reagent and the corrosion treatment time is 20~80s.

[0015] The present invention also provides a pure titanium with a surface topological structure prepared by the above-described method for preparing pure titanium with a surface topological structure, wherein the surface of the pure titanium has an array of pits and protrusions.

[0016] Preferably, the array of pits and protrusions is an equiaxial array of pits and protrusions, an array of equiaxial and elongated mixed pits and protrusions, or an elongated array of pits and protrusions.

[0017] Preferably, the width and depth of the equiaxial pit and boss array are independently 30~90nm; the length of the elongated pit and boss array is 200~6500nm, and the width and depth are independently 100~500nm.

[0018] The beneficial effects of this invention are: This invention can obtain a naturally epitaxially grown topological structure on the surface of a pure titanium implant, which greatly reduces the production cycle and cost. The pure titanium with surface topological structure prepared can exceed the strength and toughness of the most widely used titanium alloy TC4 and the third-generation titanium alloy β titanium alloy.

[0019] The pure titanium with a unique surface topology prepared in this invention exhibits excellent strength, toughness, and osteogenic properties. Its tensile yield strength is 1.7 to 2.5 times that of conventional coarse-grained pure titanium, while its uniform elongation is close to that of conventional coarse-grained pure titanium. Furthermore, the pure titanium with the optimal structure possesses mechanical properties comparable to titanium alloys TC4 and β-titanium alloys. The osteogenic cycle of the pure titanium prepared in this invention is shortened to 1 / 4 to 2 / 3 of that of conventional coarse-grained pure titanium and the aforementioned titanium alloys, achieving the same amount of new bone formation in one week as the latter would take one month.

[0020] The pure titanium prepared by this invention exhibits excellent biocompatibility because: pure titanium, as the bulk material, inherently possesses excellent biocompatibility; a specific texture is formed during processing, meaning that the crystal orientation of most grains tends to be consistent; importantly, the close-packed crystal faces of pure titanium are exposed on the surface of the rod, which facilitates the formation of anatase titanium dioxide on the surface; the surface-formed topological structure improves hydrophilicity and is conducive to the adsorption and growth of osteoblasts, greatly improving the growth environment of osteoblasts; the surface-formed topological structure allows for the addition of specific drugs to further enhance osteogenic performance.

[0021] This invention yields pure titanium rods with high strength, toughness, and excellent biocompatibility through a simple and mature process, which can widely replace titanium alloys in the field of medical implants. The preparation process of this invention is characterized by low cost, short cycle time, sufficiently large product size, and the ability to be mass-produced and industrialized. Attached Figure Description

[0022] Figure 1 SEM image of the pure titanium rod with surface topology prepared in Example 3; Figure 2 This is a depth data diagram of the surface topology of the pure titanium rod with surface topology prepared in Example 3. Detailed Implementation

[0023] This invention provides a method for preparing pure titanium with a surface topological structure, comprising the following steps: sequentially subjecting a pure titanium rod to multi-pass rotary forging, heat treatment, mechanical grinding, annealing, turning, polishing and etching to obtain pure titanium with a surface topological structure.

[0024] In this invention, the strain of the multi-pass rotary forging is 1.2~3.5, and the processing temperature is 20~300℃, specifically 20℃, 50℃, 70℃, 100℃, 150℃, 200℃, 250℃, and 300℃. The diameter reduction of each pass of rotary forging is 0.5~2mm, specifically 0.5mm, 1.0mm, 1.5mm, and 2.0mm.

[0025] In this invention, rotary forging can rapidly refine and elongate grains and adjust crystal orientation to form an ultrafine fibrous crystalline structure. By changing parameters such as temperature and deformation, the length, proportion, and orientation of the slender grains are controlled to obtain an ultrafine fibrous crystalline structure. The matrix is ​​obtained through multiple rotary forging passes, serving as the inner layer of pure titanium with a surface topological structure.

[0026] In this invention, the heat treatment is a single surface induction heat treatment, with a temperature of 400~475℃, specifically 400℃, 425℃, 450℃, or 475℃, a current of 15~80A, specifically 15A, 20A, 30A, 40A, 50A, 60A, 70A, or 80A, and a time of 2~30s, specifically 2s, 5s, 10s, 15s, 20s, 25s, or 30s.

[0027] In this invention, surface induction heat treatment can introduce equiaxed nanoscale recrystallization in a partially crystalline manner from the surface of the substrate to a specific depth. By changing the parameters such as temperature, time and number of induction heat treatments, the size of the equiaxed crystals and their depth from the surface can be controlled. A sub-surface layer composed of a non-uniform structure is obtained on the surface of the substrate through surface induction heat treatment, with a thickness of 1 mm < ≤ 4 mm.

[0028] Surface induction heat treatment, due to its short heating time and limited heat transfer to deeper layers, does not cause recrystallization of the internal ultrafine fiber crystalline structure. Instead, it only induces restorative annealing, thus preserving the intact ultrafine fiber crystalline structure of the inner layers. The non-uniform structure formed by partial recrystallization on the surface layer constitutes the subsurface microstructure, laying the foundation for subsequent processing steps. Materials treated with surface induction heat treatment have grains in a restored state with low dislocation density, providing space for dislocation generation, multiplication, and storage, thereby improving work hardening capacity and tensile plasticity. In gradient structures, synergistic deformation between layers provides additional work hardening capacity and back stress reinforcement, further enhancing the material's strength and toughness.

[0029] In this invention, the heat treatment is followed by rapid cooling.

[0030] In this invention, the temperature of the mechanical grinding is -196~20℃, specifically -196℃, -180℃, -160℃, -140℃, -120℃, -100℃, -80℃, -70℃, -60℃, -50℃, -40℃, -20℃, and -10℃, and the speed is 2~40mm / s, specifically 2mm / s, 5mm / s, 10mm / s, 15mm / s, 20mm / s, 25mm / s, 30mm / s, 35mm / s, and 40mm / s.

[0031] In this invention, mechanical grinding can refine the surface grains to the nanoscale. By changing parameters such as temperature and speed, the size of the equiaxed crystals and their depth from the surface can be controlled. Through mechanical grinding, an outer surface layer composed of uniform nanocrystals is obtained on the surface of the sub-surface layer, where 0 < thickness of the outer surface layer ≤ 1 mm.

[0032] Mechanical grinding only subjectes the surface layer at a certain depth to intense plastic deformation, rapidly refining the surface layer to nanoscale. Mechanical grinding can only process a certain depth of surface layer, and the depth processed is much smaller than the depth of the previous induction heat treatment. Therefore, the surface layer is preserved, forming a multi-layer gradient structure of pure titanium.

[0033] In this invention, the heating rate during the annealing process is 3~5℃ / min, specifically 3℃ / min, 4℃ / min, or 5℃ / min; the temperature is 300~500℃, specifically 300℃, 350℃, 400℃, 450℃, or 500℃; and the holding time is 20~40min, specifically 20min, 25min, 30min, 35min, or 40min. After the annealing process, a cooling process is performed at a cooling rate of 5~7℃ / min, specifically 5℃ / min, 6℃ / min, or 7℃ / min.

[0034] The pure titanium obtained after annealing has a three-layer stepped structure from the surface to the core. The outer layer is composed of equiaxed nanocrystals with a size of 30~90nm. The inner layer is composed of ultrafine fiber crystals with a long axis size of 200nm~6500nm and a short axis size of 100nm~500nm. The sub-surface layer is composed of equiaxed nanocrystals and ultrafine fiber crystals, and its grain size is determined by the size of the two structures that make up its structure.

[0035] Reversible annealing is used to eliminate residual stresses introduced by the above steps in the sample and restore the sample's plasticity.

[0036] In this invention, the peeling thickness during turning is 0.5~4.5mm, specifically 0.5mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, or 4.5mm.

[0037] In this invention, different layers are obtained by peeling off different thicknesses. When the peeling thickness is less than 1 mm, an equiaxial array topology can be formed on the outer layer. When 1 mm < peeling thickness < 4 mm, a mixed array topology on the sub-surface layer can be formed. When the peeling thickness is greater than 4 mm, a slender array topology on the inner layer can be formed.

[0038] In this invention, the polishing process uses a medium-short fiber ultrafine polishing cloth and a medical-grade diamond suspension as the polishing medium. The medium particle size is 1~3μm, and the polishing time for a single pass is 3~6min. The polishing process is carried out with anhydrous ethanol for temperature control throughout to ensure that the sample surface temperature does not exceed 30℃.

[0039] In this invention, the corrosion treatment uses Kroll reagent, and the corrosion treatment time is 20~80s, specifically 25s, 30s, 45s, 50s, or 75s.

[0040] The technological principle behind the formation of surface topological structures is as follows: During the rotary forging process, while refining the grains, the newly formed grains are reoriented, resulting in a regular distribution of exposed crystal faces on the surface, with grains of specific orientation occupying a significant proportion. The crystal faces of these specific grains differ considerably in hardness and wear resistance from those of other grains. During the surface polishing process, these grains experience more severe wear, leading to the formation of a natural grain-like topological structure on the surface. Furthermore, during the corrosion process, these natural topological structures expose even more crystal faces, creating a potential difference with other grains, accelerating the corrosion rate, and further promoting the formation of the grain-like topological structure.

[0041] The pure titanium prepared by this invention has both high strength and toughness and high biocompatibility, and can be preferred as a replacement for titanium alloys in the fields of biological implants and medical devices. The preparation process is simple, efficient and cost-controllable. It can be achieved by using simple and mature rotary forging, surface induction heat treatment and surface mechanical grinding processes, and can be mass-produced.

[0042] The present invention also provides a pure titanium with a surface topological structure prepared by the above-described method for preparing pure titanium with a surface topological structure, wherein the surface of the pure titanium has an array of pits and protrusions.

[0043] In this invention, the array of pits and protrusions is an equiaxial array of pits and protrusions, an equiaxial and elongated mixed array of pits and protrusions, or an elongated array of pits and protrusions.

[0044] In this invention, the width and depth of the equiaxial pit and boss array are independently 30~90nm; the length of the elongated pit and boss array is 200~6500nm, and the width and depth are independently 100~500nm.

[0045] In this invention, the pure titanium with surface topology has a yield strength range of 520MPa to 820MPa, a tensile strength range of 610MPa to 970MPa, a uniform elongation of >5%, and an elongation after fracture of >12%.

[0046] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] The pure titanium rods used in the embodiments of the present invention are of grade TA2 and conform to the technical standard GB / T3620.1-2007.

[0048] Example 1

[0049] A pure titanium bar with an initial diameter of 40 mm was subjected to multiple rotary forgings at 25°C. Each rotary forging reduced the diameter by 1.5 mm, resulting in a pure titanium bar with a final diameter of 14 mm. The total strain of the rotary forging was 2.09, forming an inner layer.

[0050] Replace the induction heating equipment with an induction heating coil adapted to a 14mm diameter bar. Perform surface induction heat treatment on a 14mm diameter pure titanium bar after rotary forging. Set the current to 45A and use an infrared instrument to detect the sample surface temperature. Automatically cut off the power when the sample surface temperature reaches 475℃. The time for a single surface induction heat treatment is 10s. Then quickly place the sample in the cooling pool below and repeat the above steps until a recrystallized layer with a thickness of 4mm is formed on the sample surface, which serves as the secondary surface layer.

[0051] A 14mm diameter pure titanium rod that has undergone surface induction heat treatment was subjected to surface mechanical grinding at a grinding temperature of -196℃ and a grinding speed of 5mm / s. This process was repeated until an outer surface layer composed of nanoscale grains with a thickness of 1mm was formed.

[0052] Subsequently, the 14mm diameter pure titanium rods that had undergone surface mechanical grinding were annealed. The titanium rods were placed in a tube furnace and evacuated. The temperature was raised from room temperature to 400℃ at a heating rate of 4℃ / min and held for 30min. Then, the temperature was lowered to ambient temperature at a cooling rate of 6℃ / min. After the vacuum tube furnace was filled with gas, the sample was taken out.

[0053] A 14mm diameter pure titanium rod that has undergone annealing was turned to remove a 0.5mm thick outer layer, followed by fine polishing. The specific process involved using a medium-short fiber ultrafine polishing cloth and a medical-grade diamond suspension as the polishing medium with a particle size of 1-3μm. Each polishing pass lasted 5 minutes, and the entire polishing process was carried out with anhydrous ethanol for temperature control to ensure that the sample surface temperature did not exceed 30℃. Finally, the pure titanium rod was etched with Kroll reagent for 25 seconds to obtain the surface metallographic structure. The outer layer of the obtained pure titanium rod has a surface topological structure.

[0054] The outer surface microstructure of the pure titanium rod in Example 1 is composed of equiaxed nanocrystals with a grain size of approximately 82 nm. The surface of the rod is formed with an array of nanoscale equiaxed pits and protrusions that are close to the size of the microstructure, with a width and depth of approximately 90 nm.

[0055] When the pure titanium bar of Example 1 is stretched along the axial direction, its yield strength is 805 MPa, tensile strength is 920 MPa, uniform elongation is 6.8%, and elongation after fracture is 16.7%.

[0056] The osteogenic cycle of the pure titanium rod in Example 1 is shortened to about 2 / 3 of that of Ti-6Al-4V.

[0057] Example 2

[0058] The difference from Example 1 is that after annealing, the surface is turned to peel off a thickness of 2.6 mm to expose the subsurface layer, and then fine polishing is performed. All other conditions are the same.

[0059] The subsurface microstructure of the pure titanium rod in Example 2 is composed of a mixture of equiaxed nanocrystals and ultrafine fiber grains. A cross-scale array of equiaxed and elongated mixed pits and protrusions is formed on the surface of the rod. The long axis dimension of the elongated pit is about 4500 nm, and its width and depth are about 500 nm.

[0060] When the pure titanium bar of Example 2 is stretched along the axial direction, its yield strength is 760 MPa, tensile strength is 840 MPa, uniform elongation is 8.2%, and elongation after fracture is 19.5%.

[0061] The osteogenic cycle of the pure titanium rod in Example 2 was shortened to about half that of Ti-6Al-4V, and the osteogenic performance was slightly improved compared with Example 1.

[0062] Example 3

[0063] The difference from Example 1 is that after annealing, the surface is machined to peel off a thickness of 4.5 mm to expose the inner layer, and then fine polishing is performed. All other conditions are the same.

[0064] The internal microstructure of the pure titanium rod in Example 3 consists of ultrafine fiber crystals, and an array of ultrafine-scale elongated pits and protrusions is formed on the surface of the rod. The long axis of the elongated pits is approximately 4500 nm, and their width and depth are approximately 500 nm. Figure 1 and Figure 2 As shown.

[0065] When the pure titanium bar of Example 3 is stretched along the axial direction, its yield strength is 820 MPa, tensile strength is 970 MPa, uniform elongation is 5.5%, and elongation after fracture is 14.2%.

[0066] The osteogenic cycle of the pure titanium rod in Example 3 was shortened to about 1 / 3 of that of Ti-6Al-4V, and the osteogenic performance was significantly improved compared with Example 1.

[0067] The test results of yield strength, tensile strength, uniform elongation and elongation after fracture of the pure titanium rods prepared in Examples 1-3 are shown in Table 1.

[0068] Table 1 Test results of pure titanium rods in Examples 1-3

[0069] In Table 1, the mechanical property standards for TA2 and TC4 are derived from GB / T 2965-2023; the mechanical properties of β titanium alloy refer to "Effect of Various Annealing Temperature on Microstructure and Properties of Metastable b-Type Ti-35Nb-2Ta-3Zr Alloy for Biomedical Applications".

[0070] As shown in Table 1, the high-strength and high-toughness pure titanium with excellent biocompatibility and customizable surface self-topology optimization prepared by this invention naturally generates a customizable self-topological structure on the surface of the bulk material without the need for additional processing technology. Moreover, the strength of the bulk material can reach 970 MPa and the elongation can reach 14.2%, which far exceeds the mechanical properties of conventional pure titanium and is close to the mechanical properties of load-bearing metal implants such as the most widely used titanium alloy TC4 and the third-generation titanium alloy β titanium alloy.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle 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 pure titanium with a surface topological structure, characterized in that, The process includes the following steps: sequentially subjecting a pure titanium rod to multiple passes of rotary forging, heat treatment, mechanical grinding, annealing, turning, polishing, and etching to obtain pure titanium with a surface topological structure.

2. The method for preparing pure titanium with a surface topological structure according to claim 1, characterized in that, The strain of the multi-pass rotary forging is 1.2~3.5, the processing temperature is 20~300℃, and the diameter reduction of each pass of rotary forging is 0.5~2mm.

3. The method for preparing pure titanium with a surface topological structure according to claim 1 or 2, characterized in that, The heat treatment is a single surface induction heat treatment, with a temperature of 400~475℃, a current of 15~80A, and a time of 2~30s.

4. The method for preparing pure titanium with a surface topological structure according to claim 3, characterized in that, The temperature of the mechanical grinding is -196~20℃, and the speed is 2~40mm / s.

5. The method for preparing pure titanium with a surface topological structure according to claim 1, 2, or 4, characterized in that, The annealing process involves a heating rate of 3-5°C / min, a temperature of 300-500°C, and a holding time of 20-40 min. After the annealing process, a cooling process is performed at a rate of 5-7°C / min.

6. The method for preparing pure titanium with a surface topological structure according to claim 5, characterized in that, The peeling thickness during turning is 0.5~4.5mm.

7. The method for preparing pure titanium with a surface topological structure according to claim 4 or 6, characterized in that, The corrosion treatment uses Kroll reagent and the corrosion treatment time is 20~80s.

8. The pure titanium with a surface topological structure prepared by the method for preparing pure titanium with a surface topological structure according to any one of claims 1 to 7, characterized in that, The surface of the pure titanium has an array of pits and protrusions.

9. The pure titanium with a surface topological structure according to claim 8, characterized in that, The array of pits and protrusions is an equiaxial array of pits and protrusions, an array of equiaxial and elongated mixed pits and protrusions, or an elongated array of pits and protrusions.

10. The pure titanium with a surface topological structure according to claim 9, characterized in that, The width and depth of the equiaxial pit and boss array are independently 30~90nm; the length of the elongated pit and boss array is 200~6500nm, and the width and depth are independently 100~500nm.

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