Medical ultra-fine fatigue-resistant tungsten wire and its preparation method

Abstract

This invention discloses an ultrafine fatigue-resistant tungsten wire rope for medical use and its preparation method, belonging to the field of tungsten wire rope technology. The invention first prepares ultrafine tungsten alloy wires with a diameter of 0.013~0.028mm through steps such as air-flow mixing, wet grinding, pre-reduction, spray doping, and multi-stage sintering; then, the wires are twisted into "7×49" or "7×37" fully homogeneous tungsten wire ropes. Through synergistic innovation in materials and structure, this invention solves the problems of easy loosening, low fatigue life, and difficulty in preparing high-performance wires in existing heterogeneous structure wire ropes. It exhibits excellent anti-rotation properties, structural stability, and bending fatigue life, and the process is highly uniform, resulting in good mass production consistency.

Description

Technical Field

[0001] This invention relates to the field of tungsten wire rope technology, specifically to a medical ultrafine fatigue-resistant tungsten wire rope and its preparation method. Background Technology

[0002] In the field of precision surgical robots for vascular and neurointerventional procedures, the key to achieving dexterous and precise intracavitary manipulation lies in the miniaturization and high reliability of their internal drive systems. As a core transmission component, the traction cable needs to possess excellent flexibility, force transmission efficiency, fatigue resistance, and structural stability within an extremely small bending radius. Tungsten wire or tungsten alloy wire, due to their high strength-to-diameter ratio and good creep resistance, has become an ideal material for manufacturing such ultra-fine traction cables.

[0003] To improve the flexibility and fatigue life of yarns, the industry has gradually evolved from simple 7×7 structures to multi-layered complex structures. Currently disclosed heterogeneous weaving methods such as "7×7+8×19" or "7×7+10×19" increase the yarn's flexibility and anti-rotation ability through combinations of different inner and outer layer configurations. However, such heterogeneous structures have significant limitations in actual manufacturing and application: First, differences in parameters such as the number of strands, filaments, twist direction, and twist pitch between the inner and outer layers make it difficult to uniformly control tension and deformation during the twisting process, affecting structural uniformity; Second, under repeated bending and torsional loads, the mismatch between the stiffness and deformation characteristics of the inner and outer layers easily leads to internal friction and stress concentration, causing the structure to loosen, deform, and decrease in stability after long-term use; Third, complex heterogeneous structures increase the difficulty of manufacturing processes and the uncertainty of quality control, making it difficult to meet the stringent requirements of surgical robots for long-life and high-reliability yarns.

[0004] On the other hand, the performance of tungsten alloy wire depends not only on its structural design but also on the properties of the wire used. Existing tungsten alloy wires are mostly produced using traditional powder metallurgy processes, such as introducing dopant elements through soaking, crystallization, or precipitation in ammonium paratungstate and rare earth salt solutions. This method tends to form larger particles, leading to reduced activity during subsequent reduction and sintering, uneven dopant distribution, and consequently affecting the wire's strength, toughness, and fatigue resistance. Furthermore, traditional processes tend to result in grain growth during reduction and sintering, limiting the strengthening effect of fine grains and making it difficult to stably produce ultrafine tungsten alloy wires with diameters below 0.02 mm and tensile strengths exceeding 5000 MPa. This restricts the potential for further reduction in wire diameter and performance improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a medical ultrafine fatigue-resistant tungsten wire rope and its preparation method, so as to solve the problems existing in the prior art.

[0006] To address the aforementioned technical problems, the present invention provides the following technical solution: a method for preparing ultrafine fatigue-resistant tungsten wire rope for medical use, wherein the tungsten wire rope is made from micron-sized tungsten alloy wire, and the preparation method of the tungsten alloy wire is as follows: S1: Ammonium paratungstate and lanthanum oxide with a particle size of 50-100 μm are subjected to air jet milling at a mass ratio of 80-100:0.2-2.5, followed by wet milling. The ball milling medium is an ethanol solution containing 5-10% PEG400 by mass. Then, pre-reduction is performed to obtain a doped tungsten precursor with microcracks on the surface. S2: By mass fraction, take 0.8-1.5 parts zirconium oxynitrate, 0.5-1.2 parts cobalt acetylacetonate, 1.0-2.5 parts polyacrylonitrile, 0.3-0.8 parts scandium oxide, and 100-150 parts of 50% ethanol aqueous solution to prepare a dopant. Spray the doped tungsten precursor with the doped material, dry it after spraying, and then sinter it at a higher temperature to obtain doped tungsten powder. S3: Tungsten powder is isostatically pressed into a blank, sintered under hydrogen protection, and then processed by blanking, pressure processing, and drawing to obtain tungsten alloy wire with a diameter of 0.013 mm-0.028 mm.

[0007] Furthermore, the powder particle size after air jet milling in step S1 is 10-40 μm.

[0008] Furthermore, in step S1, the ball-to-material ratio of the wet grinding process is 4-5:1, the ball milling time is 24-36 hours, the drying temperature is 80-100°C, and the drying time is 2-4 hours.

[0009] Furthermore, in step S1, the pre-reduction temperature is 430-450°C, the heating rate is 1-3°C / min, and the hydrogen flow rate is 0.3m³. 3 / h~0.4m 3 / h, the time is 6-8h.

[0010] Furthermore, in step S2, the spraying temperature of the dopant is 60-70℃, the spraying speed is 50-150mL / min, and the spraying amount is 100-300g of dopant / 100kg of doped tungsten precursor.

[0011] Furthermore, the heating and sintering process described in step S2 is as follows: at a hydrogen flow rate of 1.0 m³ / s... 3 / h~1.5m 3 At a temperature of / h, raise the temperature to 400-500℃ and hold for 60 minutes, raise the temperature to 850-920℃ and hold for 120 minutes, and raise the temperature to 1000-1050℃ and hold for 90 minutes.

[0012] Furthermore, the isostatic pressing pressure in step S3 is 140-240 MPa, and the weight of the compact is 1.5-5.0 kg.

[0013] Furthermore, the temperature / time parameters for the electric sintering in step S3 are as follows: 1250℃ / 90min, 1500℃ / 120min, 1800℃ / 150min, 2000℃ / 120min, 2200℃ / 180min, 2400℃ / 300min.

[0014] Furthermore, the tungsten wire rope made from the tungsten wire has a 7×49 structure or a 7×37 structure.

[0015] Furthermore, the tungsten wire rope has a 7×49 structure, which is a 7×7×7 fully homogeneous structure, i.e., 7 core strands, each strand consisting of 7×7 monofilaments. Specifically, the entire rope is composed of 1 core strand and 6 outer strands arranged closely in a "1+6" manner, while each strand consists of 49 fine filaments, and each strand continues to exhibit a "1+6" substructure. The specific preparation method includes the following steps: A. Single strand preparation: Multiple micron-sized tungsten alloy wires are twisted into 1×49 single strands with an internal structure of "1 core wire + 6 layers of outer wires" using a tubular cable forming machine, and the strand diameter is controlled to be 0.12 mm~0.21 mm; B. Preparation of the outer strand: Using the same raw materials, equipment and process parameters as in step A, prepare a single 1×49 structural strand as the outer strand; C. Joining the strands to form the core: Join the 7 strands obtained in step A in a “1+6” layout of “1 central strand + 6 outer strands” to form the core. The twist direction of each strand inside the core is opposite to the twist direction of the entire core. D. Final Rope Assembly: The rope core obtained in step C is assembled with the outer strand prepared in step B to obtain the finished tungsten wire rope, wherein the twist direction of the outer strand is opposite to the twist direction of the rope core. E. Post-processing: The tungsten wire rope after being combined is straightened and stress-relieved.

[0016] This invention employs a "7×49" fully homogeneous fractal structure in the wire rope structure, meaning the core and outer strands use identical 1×49 single-strand structures, with each strand exhibiting a "1+6" self-similar arrangement. This achieves full-scale structural consistency from the microscopic filament to the macroscopic strand, fundamentally solving the problems of uneven twisting, internal stress concentration, and easy loosening during long-term service in heterogeneous structures. By using opposite twisting directions at both the strand and rope levels in the core and outer layers, this invention maximizes the cancellation of internal torque, ensuring excellent anti-rotation capability and structural stability, maintaining high-precision transmission even under repeated bending and torsional loads. The tungsten wire rope described in this invention achieves a finer single-wire diameter for the same diameter, is compatible with high-performance tungsten alloy wires with a tensile strength of not less than 5000 MPa, significantly improves overall breaking strength, and increases bending fatigue life by more than 50% compared to traditional heterogeneous structures. The preparation method described in this invention has a highly uniform process. The entire manufacturing process requires only one single-strand structure, and the entire process from strand formation to rope formation can be completed using the same tubular cable forming machine based on the same principle. There is no need to switch equipment, which greatly reduces the complexity of the process and the difficulty of quality control, and has excellent advantages in mass production consistency and cost control.

[0017] Furthermore, the tungsten wire rope has a 7×37 structure, which is a 1+6+12+18 wire bundle arrangement. The specific preparation method includes the following steps: A. Core strand preparation: Using tungsten wire with the aforementioned specific composition and properties, it is twisted into a 1X37 structure single strand using a special cage stranding machine, controlling the single strand diameter within the range of 0.1~0.2mm. The 37-strand structure is divided into four layers: 1+6+12+18, with layer 6 twisted in the opposite direction to layer 12, and layer 12 twisted in the opposite direction to layer 18.

[0018] B. Preparation of the outer strand: Using the same tungsten wire material and process as in step A, prepare a 1X37 structural single strand with the same strand diameter as the outer strand. The twist phase of the outer strand is opposite to that of the core strand.

[0019] C. Final Rope Assembly: The core strand obtained in step A and the six outer strands obtained in step B are assembled into a rope to finally produce a complete tungsten wire rope with a diameter between 0.3 and 0.6 mm.

[0020] E. Post-assembly treatment: The tungsten wire rope after assembly is post-treated using a post-deformation equipment to eliminate stress, improve dimensional stability, and ensure its performance.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) This invention uses ammonium paratungstate and lanthanum oxide air jet milling to help achieve rapid homogenization and improve the performance of tungsten wire rope. Compared with the existing technology of soaking, crystallizing or precipitating ammonium paratungstate and rare earth salts, which easily form relatively large particles, resulting in lower activity in subsequent reduction and sintering, affecting the performance of tungsten wire rope, this invention adopts preliminary grinding to obtain high-activity narrow particle size range rare earth doped tungsten powder to produce tungsten wire rope. This not only eliminates the production scale effect limitation caused by particle size combination powder, but also obtains stable, nanoscale initial crystallization. Through powder mixing treatment, the local doping unevenness of different batches of coarse-grained powder during the reduction process is avoided, and the agglomeration and enrichment of fine-grained powder after reduction is effectively suppressed, so that the subsequent alloy powder doping micro-uniformity leads to the generation of defects in the subsequent pressure processing process and reduces the risk of wire breakage. Then, anhydrous ethanol containing PEG is added for wet grinding to prevent green cracks. Then, the temperature is slowly raised for pre-reduction, so that there is no PEG residue. Metallic tungsten and rare earth elements achieve preliminary combination, and at the same time, high-temperature pre-reduction causes certain cracks in the doped tungsten powder.

[0022] (2) The present invention uses a spray dopant, which is a solution composed of zirconium oxynitrate, cobalt acetylacetonate, and scandium oxide. The solution is sprayed onto doped tungsten powder and then sintered to form a dense tungsten alloy, thereby achieving fatigue resistance, high strength, and creep resistance. (3) The use of air jet milling, wet milling and special doping methods in this invention is beneficial to obtaining fine and uniformly distributed initial tungsten powder particles. During the densification sintering process, the doping elements pin the grain boundaries, strongly inhibit grain growth, and improve the strength and fatigue resistance of the ultrafine tungsten wire rope. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is an example image of a 7*49 (OD 0.5mm) tungsten wire rope magnified 100x; Figure 2 This is a 100x magnified comparison example of a 7*37 (OD 0.5mm) tungsten wire rope; Figure 3 This is a comparison example image of a 7*7+8*19 (OD 0.5mm) tungsten wire rope magnified 100x. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 A method for preparing tungsten alloy wire: (1) Ammonium paratungstate and lanthanum oxide with a particle size of 50 μm were subjected to air jet milling at a mass ratio of 100:0.8. The air jet milling wheel speed was 5000 rpm, the mill chamber weight was 50 kg, the grinding gas pressure was 0.7 MPa, and the powder particle size after air jet milling was 40 μm. Wet grinding was then performed using a 10% PEG40 alcohol solution as the ball milling medium, a ball-to-material ratio of 4:1, a ball milling time of 24 h, and drying at 100 °C for 4 h. The hydrogen flow rate was 0.4 m³ / h. 3 At a rate of 2°C / min, the temperature was increased to 450°C and pre-reduced for 8 hours to obtain a tungsten-doped precursor with surface cracks. (2) By mass fraction, take 1.5 parts zirconium oxynitrate, 1.2 parts cobalt acetylacetonate, 2.5 parts polyacrylonitrile, 0.8 parts scandium oxide, and 150 parts of a 50% (v / v) aqueous ethanol solution to prepare a dopant. Maintain the temperature at 70℃, the spraying speed at 150 mL / min, and the spraying amount at 200 g dopant / 100 kg doped tungsten precursor. After spraying, continue drying at 120℃ for 3.5 hours, with a hydrogen flow rate of 1.5 m³ / min. 3 At a temperature of / h, the temperature is increased to 500℃ and held for 60 min, then increased to 920℃ and held for 120 min, then increased to 1050℃ and held for 90 min to obtain doped tungsten powder; (3) The doped tungsten powder was pressed into a compact weighing 5.0 kg by isostatic pressing at 240 MPa. Under hydrogen protection, it was sintered by electric current. The temperature / time parameters were as follows: 1250℃ / 90 min, 1500℃ / 120 min, 1800℃ / 150 min, 2000℃ / 120 min, 2200℃ / 180 min, 2400℃ / 300 min. After blanking, pressure processing and drawing, a tungsten alloy wire with a diameter of 0.024 mm was obtained.

[0026] Example 2 A method for preparing tungsten alloy wire: (1) Ammonium paratungstate, lanthanum oxide with a particle size of 50 μm, and scandium oxide with a particle size of 50 μm were mixed in an air jet mill at a mass ratio of 100:0.5. The air jet mill separator speed was 3000 rpm, the mill chamber weight was 70 kg, the grinding gas pressure was 0.4 MPa, and the powder particle size after air jet milling was 10 μm. Wet grinding was then performed using a 5% PEG40 alcohol solution as the ball milling medium, with a ball-to-material ratio of 5:1 and a ball milling time of 36 h. The powder was dried at 80 °C for 2 h, and the hydrogen flow rate was 0.3 m³ / h. 3 At a rate of 2°C / min, the temperature was increased to 430°C and pre-reduced for 6 hours to obtain a tungsten-doped precursor with surface cracks. (2) By mass fraction, take 0.8 parts zirconium oxynitrate, 0.5 parts cobalt acetylacetonate, 1.0 part polyacrylonitrile, 0.3 parts scandium oxide, and 100 parts of 50% ethanol aqueous solution to prepare a dopant. Maintain the temperature at 60℃, the spraying speed at 50 mL / min, and the spraying amount at 300 g dopant / 100 kg doped tungsten precursor. After spraying, continue drying at 100℃ for 3.5 hours, with a hydrogen flow rate of 1.0 m³ / min. 3 At a temperature of / h, the temperature is increased to 400℃ and held for 60 min, then increased to 850℃ and held for 120 min, then increased to 1000℃ and held for 90 min to obtain doped tungsten powder; (3) The doped tungsten powder was pressed into a compact weighing 1.5 kg by isostatic pressing at 140 MPa. Under hydrogen protection, it was sintered by electric current. The temperature / time parameters were as follows: 1250℃ / 90 min, 1500℃ / 120 min, 1800℃ / 150 min, 2000℃ / 120 min, 2200℃ / 180 min, 2400℃ / 300 min. After blanking, pressure processing and drawing, a tungsten alloy wire with a diameter of 0.024 mm was obtained.

[0027] Example 3 A method for preparing tungsten alloy wire: (1) Ammonium paratungstate and lanthanum oxide with a particle size of 50 μm were subjected to air jet milling at a mass ratio of 90:1.0. The air jet milling wheel speed was 4000 rpm, the mill chamber weight was 60 kg, the grinding gas pressure was 0.5 MPa, and the powder particle size after air jet milling was 25 μm. Wet grinding was then performed using a 5% PEG40 alcohol solution as the ball milling medium, with a ball-to-material ratio of 4:1 and a ball milling time of 30 h. The powder was then dried at 90 °C for 3 h, with a hydrogen flow rate of 0.35 m³ / h. 3 At a rate of 2℃ / min, the temperature was increased to 440℃ and pre-reduced for 7h to obtain a tungsten-doped precursor with surface cracks. (2) By mass fraction, take 1.0 part zirconium oxynitrate, 0.8 part cobalt acetylacetonate, 1.8 parts polyacrylonitrile, 0.5 part scandium oxide, and 120 parts of 50% ethanol aqueous solution to prepare a dopant. Maintain the temperature at 65℃, the spraying speed at 100mL / min, and the spraying amount at 100g dopant / 100kg doped tungsten precursor. After spraying, continue drying at 110℃ for 3.5 hours, with a hydrogen flow rate of 1.2m. 3 At a temperature of / h, the temperature is increased to 450℃ and held for 60 min, then increased to 880℃ and held for 120 min, then increased to 1025℃ and held for 90 min to obtain doped tungsten powder; (3) The doped tungsten powder was pressed into a compact weighing 3.0 kg by isostatic pressing at 190 MPa. Under hydrogen protection, it was sintered by electric current. The temperature / time parameters were as follows: 1250℃ / 90 min, 1500℃ / 120 min, 1800℃ / 150 min, 2000℃ / 120 min, 2200℃ / 180 min, 2400℃ / 300 min. After blanking, pressure processing and drawing, a tungsten alloy wire with a diameter of 0.024 mm was obtained.

[0028] Example 4 A method for preparing tungsten alloy wire: (1) Ammonium paratungstate, lanthanum oxide with a particle size of 50 μm, and scandium oxide with a particle size of 50 μm were subjected to air jet milling at a mass ratio of 85:1.8:2.0. The air jet milling wheel speed was 3500 rpm, the mill chamber weight was 65 kg, the grinding gas pressure was 0.45 MPa, and the powder particle size after air jet milling was 15 μm. Wet grinding was then performed using a 5% PEG40 alcohol solution as the ball milling medium, with a ball-to-material ratio of 4:1 and a ball milling time of 32 h. The powder was then dried at 95 °C for 2.5 h, with a hydrogen flow rate of 0.32 m³ / h. 3 At a rate of 2℃ / min, the temperature was increased to 435℃ and pre-reduced for 6.5h to obtain a tungsten-doped precursor with surface cracks. (2) By mass fraction, take 0.9 parts zirconium oxynitrate, 0.7 parts cobalt acetylacetonate, 1.2 parts polyacrylonitrile, 0.4 parts scandium oxide, and 110 parts of a 50% (v / v) aqueous ethanol solution to prepare a dopant. Maintain the temperature at 62℃, the spraying speed at 70 mL / min, and the spraying amount at 200 g dopant / 100 kg doped tungsten precursor. After spraying, continue drying at 105℃ for 3.5 hours, with a hydrogen flow rate of 1.1 m³ / min. 3 At a temperature of / h, the temperature is increased to 480℃ and held for 60 min, then increased to 900℃ and held for 120 min, then increased to 1010℃ and held for 90 min to obtain doped tungsten powder; (3) The doped tungsten powder was pressed into a blank with a single weight of 2.0 kg by isostatic pressing at 160 MPa. Under hydrogen protection, it was sintered by electric current. The temperature / time parameters were as follows: 1250℃ / 90 min, 1500℃ / 120 min, 1800℃ / 150 min, 2000℃ / 120 min, 2200℃ / 180 min, 2400℃ / 300 min. After blanking, pressure processing and drawing processing, a tungsten alloy wire with a diameter of 0.024 mm was obtained.

[0029] Example 5 A method for preparing tungsten alloy wire: (1) Ammonium paratungstate, lanthanum oxide with a particle size of 50 μm, and scandium oxide with a particle size of 50 μm were subjected to air jet milling at a mass ratio of 95:1.5:1.5. The air jet milling wheel speed was 4500 rpm, the milling chamber weight was 55 kg, the grinding gas pressure was 0.6 MPa, and the powder particle size after air jet milling was 20 μm. Wet grinding was then performed using a 5% PEG40 alcohol solution as the ball milling medium, with a ball-to-material ratio of 5:1 and a ball milling time of 28 h. The powder was dried at 85 °C for 3 h, and the hydrogen flow rate was 0.36 m³ / h. 3 At a rate of 2℃ / min, the temperature was increased to 445℃ and pre-reduced for 7h to obtain a tungsten-doped precursor with surface cracks. (2) By mass, take 1.2 parts zirconium oxynitrate, 1.0 parts cobalt acetylacetonate, 2.0 parts polyacrylonitrile, 0.7 parts scandium oxide, and 130 parts of 50% ethanol aqueous solution to prepare a dopant. Maintain the temperature at 68℃, the spraying speed at 80mL / min, and the spraying amount at 100g dopant / 100kg doped tungsten precursor. After spraying, continue drying at 115℃ for 3.5 hours, with a hydrogen flow rate of 1.3m³ / min. 3 At a temperature of / h, the temperature is increased to 470℃ and held for 60 min, then increased to 890℃ and held for 120 min, then increased to 1030℃ and held for 90 min to obtain doped tungsten powder; (3) The doped tungsten powder was pressed into a blank with a single weight of 4.0 kg by isostatic pressing at 220 MPa. Under hydrogen protection, it was sintered by electric current. The temperature / time parameters were as follows: 1250℃ / 90 min, 1500℃ / 120 min, 1800℃ / 150 min, 2000℃ / 120 min, 2200℃ / 180 min, 2400℃ / 300 min. After blanking, pressure processing and drawing processing, a tungsten alloy wire with a diameter of 0.024 mm was obtained.

[0030] Table 1 Comparison of tungsten wires in the examples Table 2 Comparison of Tungsten Wire Rope Structures As shown in the comparison data in the table above, under the same rope diameter, this invention achieves a single filament diameter of 0.024 mm and 0.019 mm, which allows it to be safely compatible with advanced tungsten alloy wires that have higher strength and a certain degree of brittleness, thereby directly improving the overall load-bearing capacity of the rope. Simultaneously, the extremely fine single filaments endow the rope with superior flexibility and a smaller minimum bending diameter, providing a foundation for the flexible movement of the surgical robot's end effector within confined cavities. Test data clearly shows that the bending fatigue life of both fully homogeneous structures (7×49 and 7×37) far exceeds that of the traditional heterogeneous composite structure (7×7+8*19). This confirms the fundamental advantages of homogenization design in eliminating internal stress concentration and achieving uniform load distribution, effectively solving the inherent problems of loosening and short lifespan of heterogeneous structures in the prior art. This invention, through the synergistic design of a fully homogeneous structure and "core-outer layer opposite twist direction," achieves optimal torque balance and anti-rotation performance, ensuring accurate positioning in precision transmission and long-term shape stability.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing a medical ultrafine fatigue-resistant tungsten wire rope, characterized in that, The tungsten wire rope is made of micron-sized tungsten alloy wire, and the preparation method of the tungsten alloy wire is as follows: S1: Ammonium paratungstate and lanthanum oxide with a particle size of 50-100 μm are subjected to air jet milling at a mass ratio of 80-100:0.2-2.5, followed by wet milling. The ball milling medium is an ethanol solution containing 5-10% PEG400 by mass. Then, pre-reduction is performed to obtain a doped tungsten precursor with microcracks on the surface. S2: By mass fraction, take 0.8-1.5 parts zirconium oxynitrate, 0.5-1.2 parts cobalt acetylacetonate, 1.0-2.5 parts polyacrylonitrile, 0.3-0.8 parts scandium oxide, and 100-150 parts of 50% ethanol aqueous solution to prepare a dopant. Spray the doped tungsten precursor with the doped material, dry it after spraying, and then sinter it at a higher temperature to obtain doped tungsten powder. S3: Tungsten powder is isostatically pressed into a blank, sintered under hydrogen protection, and then processed by blanking, pressure processing, and drawing to obtain tungsten alloy wire with a diameter of 0.013 mm-0.028 mm.

2. The method for preparing a medical ultrafine fatigue-resistant tungsten wire rope according to claim 1, characterized in that, The powder particle size after air jet milling in step S1 is 10-40 μm.

3. The method for preparing a medical ultrafine fatigue-resistant tungsten wire rope according to claim 1, characterized in that, In step S1, the ball-to-material ratio of wet grinding is 4-5:1, the ball milling time is 24-36 hours, the drying temperature is 80-100℃, and the drying time is 2-4 hours.

4. The method for preparing a medical ultrafine fatigue-resistant tungsten wire rope according to claim 1, characterized in that, The pre-reduction temperature in step S1 is 430-450℃, the heating rate is 1-3°C / min, and the hydrogen flow rate is 0.3m³. 3 / h~0.4m 3 / h, the time is 6-8h.

5. The method for preparing a medical ultrafine fatigue-resistant tungsten wire rope according to claim 1, characterized in that, In step S2, the spraying temperature of the dopant is 60-70℃, the spraying speed is 50-150mL / min, and the spraying amount is 100-300g of dopant / 100kg of doped tungsten precursor.

6. The method for preparing a medical ultrafine fatigue-resistant tungsten wire rope according to claim 1, characterized in that, The heating and sintering process described in step S2 is as follows: At a hydrogen flow rate of 1.0 m³ / s... 3 / h~1.5m 3 At a temperature of / h, raise the temperature to 400-500℃ and hold for 60 minutes, raise the temperature to 850-920℃ and hold for 120 minutes, and raise the temperature to 1000-1050℃ and hold for 90 minutes.

7. The method for preparing a medical ultrafine fatigue-resistant tungsten wire rope according to claim 1, characterized in that, The isostatic pressing pressure in step S3 is 140-240 MPa, and the weight of the compact is 1.5-5.0 kg.

8. The method for preparing a medical ultrafine fatigue-resistant tungsten wire rope according to claim 1, characterized in that, The temperature / time parameters for the sintering in step S3 are as follows: 1250℃ / 90min, 1500℃ / 120min, 1800℃ / 150min, 2000℃ / 120min, 2200℃ / 180min, 2400℃ / 300min.

9. The method for preparing a medical ultrafine fatigue-resistant tungsten wire rope according to claim 1, characterized in that, The tungsten wire rope made from the tungsten wire has a 7×49 structure or a 7×37 structure.

10. The method for preparing a medical ultrafine fatigue-resistant tungsten wire rope according to claim 1, characterized in that, The tungsten wire rope has a 7×49 structure, which is a 7×7×7 fully homogeneous structure, that is, 7 core strands, each strand is composed of 7×7 monofilaments. Specifically, the whole rope is composed of 1 core strand and 6 outer strands arranged closely in a "1+6" manner, while each strand is composed of 49 fine filaments, and each strand continues to present a "1+6" substructure. The tungsten wire rope has a 7×37 structure, which is a bundle arrangement of 1+6+12+18 wires.

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