A biodegradable low-silicon ferromanganese alloy material and a preparation method and application thereof

Abstract

The application relates to a biodegradable low-silicon iron-manganese alloy material and a preparation method and application thereof, through synergistic regulation of Si and N in the Fe-Mn-Si-N alloy, the Fe-Mn-Si-N effectively improves the elastic modulus and ductility of the Fe-Mn-Zn-Si on the basis of meeting the CT / MRI imaging requirement, the strength meets the requirement, and then the elasticity, compression release effect and shape memory effect of the stent prepared from the Fe-Mn-Zn-Si alloy are improved; through synergistic regulation of Si and N in the Fe-Mn-Si-N alloy, the polarization current density is increased, the corrosion driving force of the Fe-Mn-Si-N alloy is significantly improved, the degradation rate of the Fe-Mn-Si-N alloy is greatly improved, and controllable degradation is realized.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable implantable medical device technology, specifically relating to a biodegradable low-silicon iron-manganese alloy material, its preparation method, and its application. Background Technology

[0002] Portal hypertension is a clinical syndrome caused by a pathological and persistent increase in the portal vein pressure gradient. It commonly occurs in patients with advanced liver disease, but can also be seen in patients with hepatic sinusoids syndrome, portal vein thrombosis, etc. Clinical manifestations include abdominal distension, varicose collateral vessels, ascites, and gastrointestinal bleeding. Without timely and effective treatment, the patient's quality of life will decline sharply, and death may even result from ruptured varicose veins in the gastrointestinal tract. Transjugular intrahepatic portosystemic shunt (TIPS) is a highly effective and rapid method to reduce portal hypertension. Through minimally invasive intervention, a stent is used to create a shunt between the portal venous system and the vena cava system, significantly reducing portal vein pressure. This is beneficial for improving liver function and symptoms, significantly improving the patient's quality of life, prolonging survival time, and buying time for the treatment of liver disease.

[0003] Shape memory alloys (SMAs) made from the biodegradable ternary iron-manganese alloy material Fe-Mn-Si are attracting attention for their use in the fabrication of TIPS scaffolds due to their advantages such as low cost, rapid degradation rate, good mechanical properties, excellent processing performance, and high corrosion resistance. In the Fe-Mn-Si ternary iron-manganese alloy system, Mn is one of the key elements affecting alloy performance. Firstly, an Mn content in the range of 20wt%~35wt% imparts diamagnetic properties to the alloy system, transforming pure Fe from ferromagnetic to non-ferromagnetic, thus giving the Fe-Mn-Si alloy good MRI imaging properties. Secondly, Mn is an essential nutrient for bone formation, lipid, amino acid, and carbohydrate metabolism, exhibiting biocompatibility. However, excessively high Mn content leads to banded structures in the alloy, reducing its strength. Furthermore, increased Mn atom concentration at grain boundaries reduces intergranular bonding forces within the alloy, thereby decreasing impact toughness and inducing brittleness. This leads to a situation in the Fe-Mn-Si alloy system where the Mn content must be high enough to meet the concentration requirements for generating diamagnetism, while also ensuring that the Mn content is not too high to meet the requirements for not reducing the alloy's strength and impact toughness. Once the Mn content in the Fe-Mn-Si alloy system is determined, it is difficult to simultaneously meet the above requirements, i.e., there is a physical contradiction.

[0004] Meanwhile, in the Fe-Mn-Si ternary iron-manganese alloy system, Si is also one of the important elements affecting the alloy properties. On the one hand, Si can lower the Neel transformation temperature of Fe-Mn-Si alloys; on the other hand, Si can regulate the segregation of Mn in the alloy, suppress the magnetic phase transformation caused by excessive Mn content, increase the amount of stress-induced martensite formation, and improve the reversibility of martensitic phase transformation. At the same time, Si helps to suppress dislocation slip, promote the formation of stacking faults in the alloy, form solid solution strengthening, improve the yield strength of the alloy, and reduce the proportion of plastic deformation, enabling the alloy to obtain shape memory effect and improve the shape memory performance of Fe-Mn-Si based alloys. However, when the Si content exceeds 6 wt%, high Si combined with high Mn will cause Fe-Mn-Si based shape memory alloys to become embrittled. Summary of the Invention

[0005] The purpose of this invention is to provide a biodegradable low-silicon iron-manganese alloy material that, with sufficient Mn content to meet the antimagnetic requirements of iron-manganese alloys, solves the problems of reduced strength, reduced impact toughness, and brittleness in Fe-Mn-Si alloys caused by excessive Mn content.

[0006] The biodegradable low-silicon iron-manganese alloy material of the present invention comprises: The mass percentage of Mn is 20%~30%; The mass percentage of Si is 1%~2%; The mass percentage of N is 0.05% to 0.1%; the balance is Fe.

[0007] Compared with existing technologies, the biodegradable low-silicon iron-manganese alloy material provided by this invention introduces N into the Fe-Mn-Si ternary system while maintaining the Si content at a low level. This allows the shape-memory Fe-Mn-Si alloy to achieve improved strength and impact toughness while maintaining controllable corrosion rate and good MRI imaging properties, and also prevents embrittlement. N is a biocompatible element, and its introduction can enhance the strength of the Fe-Mn-Si alloy through solid solution strengthening and improve the alloy toughness by inhibiting Mn grain boundary segregation, thereby balancing the embrittlement tendency caused by excessive Mn content. At the same time, the interstitial atomic characteristics of N can refine the grains, reduce the electrode potential difference of the Fe-Mn-Si alloy, and form micro-region electrochemical corrosion units with the Fe matrix, promoting a controllable degradation process. Low Si content (1wt%~2wt%) improves the yield strength of Fe-Mn-Si alloys while avoiding embrittlement. It works synergistically with the introduced N to regulate and suppress grain boundary segregation of high Mn content, improve the toughness and reversibility of shape memory effect of Fe-Mn-Si alloys, and jointly regulate the mechanical properties, phase transformation characteristics and degradation rate of the alloy.

[0008] Furthermore, it also includes C, wherein the mass percentage of C is 0.05% to 0.1%. The introduction of C can further improve the hardness and yield strength of Fe-Mn-Si-N alloy, hinder dislocation slip by forming nanoscale carbides, increase the efficiency of stress-induced martensite formation, and at the same time, the potential difference between the carbides and the matrix can regulate the degradation kinetics, forming a uniform corrosion mode and resulting in better degradation effect.

[0009] Furthermore, it also includes Ti, wherein the mass percentage of Ti is 0.05% to 0.1%. As a strong carbide-forming element, Ti can form stable intermetallic compounds with Fe, improving the corrosion resistance and high-temperature stability of the alloy. At the same time, by suppressing dislocation movement during the inverse martensitic transformation, it further enhances the reversibility of the shape memory effect. It can also optimize the interface matching degree between the austenite and martensite phases, improve the phase transformation driving force, and make the synergistic regulation ability of the composite addition of N, C and Ti stronger, resulting in better mechanical properties, phase transformation characteristics and degradation rate of the Fe-Mn-Si-NC-Ti alloy.

[0010] Meanwhile, this invention provides a method for preparing a biodegradable low-silicon iron-manganese alloy material, comprising the following steps: S10 involves smelting raw materials pure iron, electrolytic Mn, MnN, and Si into a block alloy, wherein the total mass percentage of electrolytic Mn and MnN is 20wt%~30wt%, the mass percentage of Si is 1wt%~2wt%, the mass percentage of N is 0.05wt%~0.1wt%, and the balance is Fe.

[0011] S20 involves homogenizing the bulk alloy under a set annealing temperature, annealing time, and vacuum environment to obtain the FeMnSi-N alloy.

[0012] Compared with the prior art, the present invention provides a method for preparing a biodegradable low-silicon iron-manganese alloy material. The preparation method is simple, and the prepared biodegradable low-silicon iron-manganese alloy material has the same beneficial effects as the above-mentioned biodegradable low-silicon iron-manganese alloy material, which will not be elaborated here.

[0013] Furthermore, the raw materials for smelting in step S10 also include C, or C and Ti, wherein the mass percentage of C is 0.05wt%~0.1wt% and the mass percentage of Ti is 0.05wt%~0.1wt%.

[0014] Furthermore, the purity of the raw materials smelted in step S10, namely pure iron, electrolytic Mn, MnN, Si, C, and Ti, is ≥99.9%.

[0015] Furthermore, the annealing temperature is set to 1000℃~1100℃; the annealing time is set to 5 hours~7 hours; and the vacuum degree in the vacuum environment is 10.-3 ~10 -5 Pa.

[0016] Meanwhile, this invention provides an application of a biodegradable low-silicon iron-manganese alloy material for preparing a biodegradable TIPS scaffold with controllable corrosion rate, comprising the following preparation steps: S30 The biodegradable low-silicon iron-manganese alloy material described in any of the above items is drawn into wire to obtain FeMn Si-N alloy wire. S40 involves braiding Fe Mn Si-N alloy wires using a structural braiding pattern with sine curves as the basic unit to obtain a self-expanding Fe Mn Si-N alloy bare scaffold. S50 uses a coating material to coat the self-expanding FeMnSi-N alloy bare scaffold.

[0017] Compared with the prior art, the biodegradable TIPS scaffold with controllable corrosion rate prepared by the above-mentioned biodegradable low silicon iron manganese alloy material provided by the present invention can be degraded in vivo without toxic side effects; and the scaffold has good elasticity, shape memory effect and compression release effect.

[0018] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation method of the biodegradable low-silicon iron-manganese alloy material of the present invention; Figure 2 This is a schematic diagram illustrating the application process of the biodegradable low-silicon iron-manganese alloy material of the present invention. Figure 3 A schematic diagram of a self-expanding bare biliary stent prepared according to an embodiment of the present invention; Figure 4 for Figure 3 Schematic diagram of the coating process; Figure 5 This is a schematic diagram of a self-expanding bare vascular stent graft prepared according to one embodiment of the present invention; Figure 6 These are constant voltage polarization curves of Examples 1-6 and Comparative Examples 1-3 of the present invention; Figure 7 These are open-circuit potential curves for Embodiments 1-6 and Comparative Examples 1-3 of the present invention; Figure 8 This is a comparison image of the corrosion process before and after in Example 1 of the present invention; Figure 9 This is a comparison image of the corrosion process before and after in Example 2 of the present invention; Figure 10 This is a comparison image of the corrosion process before and after in Example 3 of the present invention; Figure 11 This is a comparison image of the corrosion process before and after in Example 4 of the present invention; Figure 12 This is a comparison image of the corrosion process before and after in Example 5 of the present invention; Figure 13 This is a comparison image of the corrosion process before and after in Example 6 of the present invention; Figure 14 This is a comparison image of Comparative Example 1 of the present invention before and after corrosion; Figure 15 This is a comparison image of Comparative Example 2 of the present invention before and after corrosion; Figure 16 This is a comparison image of Comparative Example 3 of the present invention before and after corrosion. Detailed Implementation

[0020] To facilitate understanding of the present invention, a more comprehensive and detailed description of the present invention will be provided below, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0021] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0022] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention are well known in the art, but do not limit the implementation of this invention. Other reagents and equipment well known in the art can also be applied to the implementation of the following embodiments of this invention.

[0023] To address the issues of reduced strength and decreased toughness in existing high-manganese-content biodegradable shape memory alloys Fe-Mn-Si while maintaining imaging compatibility in medical imaging examinations, this invention proposes a biodegradable low-silicon iron-manganese alloy material. By introducing N into the Fe-Mn-Si alloy and reducing the Si content, the shape memory Fe-Mn-Si alloy can improve its strength and impact toughness while maintaining controllable corrosion rate and good MRI imaging properties, and prevent the Fe-Mn-Si alloy from becoming embrittled.

[0024] Please see Figure 1 The following details the preparation method of the biodegradable low-silicon iron-manganese alloy material of this application, including the following steps.

[0025] S10 is made by melting raw materials pure iron, electrolytic Mn, MnN, and Si into a block alloy.

[0026] In practice, a high-frequency electromagnetic induction melting furnace or an electric arc induction melting furnace is used to melt pure iron, electrolytic Mn, MnN, and Si. The high-frequency electromagnetic induction melting furnace or the electric arc induction melting furnace rapidly melts the above raw materials using a high-power current, reducing the volatilization of Mn. Specifically, the electrolytic Mn and MnN have a combined Mn mass percentage of 20%~30%, Si a mass percentage of 1%~2%, and N a mass percentage of 0.05%~0.1%.

[0027] In some embodiments, the raw materials smelted in step S10 further include C, or C and Ti, wherein the mass percentage of C is 0.05% to 0.1% and the mass percentage of Ti is 0.05% to 0.1%.

[0028] In some embodiments, the purity of the raw materials smelted in step S10, including pure iron, electrolytic Mn, MnN, Si, C, and Ti, is ≥99.9%.

[0029] S20 involves homogenizing the bulk alloy under a set annealing temperature, annealing time, and vacuum environment to obtain the FeMnSi-N alloy.

[0030] In practice, the annealing temperature is set to 1000℃~1100℃, and the annealing time is set to 5 hours~7 hours. The annealing is performed under vacuum conditions with a vacuum level of 10⁻³~10⁻⁵ Pa. Homogenization annealing can make the FeMnSi-N alloy have a uniform microstructure and composition, eliminate material defects, and improve plasticity and ductility.

[0031] Fe Mn Si-N alloy can be prepared according to steps S10 and S20. If C and Ti are added to the raw materials in step S10, Fe Mn Si-N alloy containing C or Fe Mn Si-N alloy containing C and Ti can be prepared.

[0032] The Fe Mn Si-N alloy, or Fe Mn Si-N alloy containing C, or Fe Mn Si-N alloy containing C and Ti, prepared above, is ground to remove its outer skin and cut into regular shapes using a wire cutting machine. It can then be used to prepare biodegradable TIPS scaffolds with controllable corrosion rates.

[0033] Please see Figure 2 The following describes in detail the method of preparing biodegradable TIPS scaffolds with controllable corrosion rate using FeMnSi-N alloy, including the following steps.

[0034] S30 is used to draw Fe Mn Si-N alloy into wire to obtain Fe Mn Si-N alloy wire.

[0035] In practice, the diameter of the FeMnSi-N alloy wire is controlled between 0.10mm and 0.25mm.

[0036] S40 involves weaving Fe Mn Si-N alloy wires using a sine curve as the basic structural unit to obtain a self-expanding Fe Mn Si-N alloy bare scaffold.

[0037] Please refer to step 3. In step S40, a sine curve is used as the basic unit to form a ring. The peaks and troughs of adjacent rings are connected to form a cylindrical self-expanding FeMnSi-N alloy bare stent. The weaving length and diameter of this self-expanding FeMnSi-N alloy bare stent are determined according to its application scenario. For example, when applied to the bile duct, its length is 40~120mm and its diameter is 6~12mm; when applied to blood vessels, its length is 60~120mm and its diameter is 6~12mm.

[0038] S50 uses a coating material to coat the self-expanding FeMnSi-N alloy bare scaffold.

[0039] For specific implementation details, please refer to [link / reference]. Figure 4 , Figure 5 One or both ends of a self-expanding FeMnSi-N alloy bare stent may not be covered. Whether the two ends of the stent are covered and the length of the uncovered length are determined according to the application scenario. Generally, 5mm to 10mm of the length of the uncovered length is left at each end of the stent. For example, when the stent is applied to a blood vessel, 20mm of the stent portal vein end is left uncovered.

[0040] In terms of biocompatibility, the coating material must be non-toxic, not cause rejection reactions, and possess excellent antithrombotic properties and cell compatibility. In terms of mechanical properties, it must have good compliance, good softness and transportability, be easily deployed to the affected area, and have sufficient tensile strength and ultra-thin thickness. In some embodiments, polycaprolactone (PCL) fibers prepared by electrospinning are used as the coating material. The diameter of the PCL fibers is less than 100 nm, and the inner diameter of the PCL fiber coating is determined according to the application scenario. For example, the inner diameter of a self-expanding FeMnSi-N alloy bare scaffold is 6 mm, so the inner diameter of the PCL fiber coating is also 6 mm. The electrospinning parameters are: voltage of 10KV~15KV, spinning distance of 20cm~30cm, and spinning solution concentration of approximately 0.5g / mL~0.9g / mL.

[0041] The technical solutions and effects of the present invention will be further described below with reference to embodiments and comparative examples. It should be noted that the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] Example 1 This embodiment prepares Fe-28Mn-1Si-0.05NC-Ti alloy and self-expanding Fe-28Mn-1Si-0.05NC-Ti biliary stent grafts. The specific preparation method is shown below.

[0043] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, MnN, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the N content is 0.05wt%, the Si content is 1wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0044] S20 homogenized the bulk alloy by annealing it in a vacuum environment at 1050℃ for 5 hours to obtain the Fe-28Mn-1Si-0.05NC-Ti alloy.

[0045] The outer skin of the Fe-28Mn-1Si-0.05NC-Ti alloy from step S20 is ground off, and it is cut into regular samples using a wire EDM machine. Steps S30 to S50 are performed on each sample.

[0046] S30 is used to draw Fe-28Mn-1Si-0.05NC-Ti alloy into wires, resulting in Fe-28Mn-1Si-0.05NC-Ti alloy wires with a diameter of 0.2 mm.

[0047] S40 uses Fe-28Mn-1Si-0.05NC-Ti alloy wires woven in a structural braiding pattern with a sine curve as the basic unit to obtain a self-expanding Fe-28Mn-1Si-0.05NC-Ti bare biliary stent with a length of 80mm and a diameter of 6mm.

[0048] S50 uses polycaprolactone (PCL) fibers prepared by electrospinning as a coating material to coat a self-expanding Fe-28Mn-1Si-0.05NC-Ti alloy bare scaffold, leaving 10mm uncoated at both ends of the scaffold.

[0049] Example 2 In this embodiment, Fe-28Mn-2Si-0.05NC-Ti alloy and self-expanding Fe-28Mn-2Si-0.05NC-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0050] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, MnN, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the N content is 0.05wt%, the Si content is 2wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0051] Example 3 In this embodiment, Fe-28Mn-1Si-0.08NC-Ti alloy and self-expanding Fe-28Mn-1Si-0.08NC-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0052] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, MnN, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the N content is 0.08wt%, the Si content is 1wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0053] Example 4 In this embodiment, Fe-28Mn-2Si-0.08NC-Ti alloy and self-expanding Fe-28Mn-2Si-0.08NC-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0054] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, MnN, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the N content is 0.08wt%, the Si content is 2wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0055] Example 5 In this embodiment, Fe-28Mn-1Si-0.1NC-Ti alloy and self-expanding Fe-28Mn-1Si-0.1NC-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0056] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, MnN, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the N content is 0.1wt%, the Si content is 1wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0057] Example 6 In this embodiment, Fe-28Mn-2Si-0.1NC-Ti alloy and self-expanding Fe-28Mn-2Si-0.1NC-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0058] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, MnN, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the N content is 0.1wt%, the Si content is 2wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0059] Comparative Example 1 In this embodiment, Fe-28Mn-0.05NC-Ti alloy and self-expanding Fe-28Mn-0.05NC-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0060] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, MnN, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the N content is 0.05wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0061] Comparative Example 2 This embodiment prepares Fe-28Mn-0.08NC-Ti alloy and self-expanding Fe-28Mn-0.08NC-Ti biliary stent graft. The preparation method is basically the same as in Example 1, except for step S10.

[0062] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, MnN, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the N content is 0.08wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0063] Comparative Example 3 In this embodiment, Fe-28Mn-0.1NC-Ti alloy and self-expanding Fe-28Mn-0.1NC-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0064] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, MnN, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the N content is 0.1wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0065] Comparative Example 4 In this embodiment, Fe-28Mn-1Si-C-Ti alloy and self-expanding Fe-28Mn-1Si-C-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0066] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the Si content is 1wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0067] Comparative Example 5 In this embodiment, Fe-28Mn-2Si-C-Ti alloy and self-expanding Fe-28Mn-2Si-C-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0068] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, Si, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the Si content is 2wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe.

[0069] Comparative Example 6 In this embodiment, Fe-28Mn-C-Ti alloy and self-expanding Fe-28Mn-C-Ti biliary stent were prepared. The preparation method was basically the same as in Example 1, except for step S10.

[0070] S10 uses an arc induction melting furnace to melt raw materials pure iron, electrolytic Mn, C, and Ti into a block alloy, wherein the Mn content is 28wt%, the C content is 0.065wt%, the Ti content is 0.07wt%, and the remainder is Fe. Results Test Analysis To verify the synergistic effect of the Si and N ratio in the Fe-Mn-Si-NC-Ti alloy, an orthogonal experimental design was employed, with Si and N included as factors. Mechanical properties of the biliary stents prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were analyzed, particularly the elastic modulus and elongation. When shape memory alloys are used in the stent field, their elastic modulus and elongation are particularly important. The elastic modulus describes a material's resistance to deformation within its elastic range, reflecting its stiffness. For stents, the elastic modulus is crucial in applications requiring high stability in maintaining a specific shape and dimensions. A suitable elastic modulus ensures that the stent does not deform excessively under normal stress, thus guaranteeing its proper support and positioning functions; for example, orthopedic implanted stents must maintain a stable support shape within the human body. If the elastic modulus is too low, the stent is prone to large deformation under small external forces, and cannot effectively support the object it carries. For example, the vascular stent cannot provide stable support for the blood vessel wall, affecting the normal shape of the blood vessel and blood flow. On the other hand, if the elastic modulus is too high, it may lead to poor mechanical compatibility with the surrounding tissues. For example, when in contact with biological tissues, it may be too rigid to adapt to the normal micro-movements of the tissues, which may easily cause adverse effects such as local stress concentration.

[0071] The elastic modulus, elongation, yield strength, tensile strength, constant voltage polarization, and open circuit voltage are tested in accordance with relevant national and industry standards.

[0072] Table 1. Effects of Si and N variations on the mechanical properties of biliary stent grafts Table 2. Range analysis of mechanical properties in Si-N synergistic changes in biliary stent grafts. The range calculation formula is R=X max -X min .

[0073] As can be seen from the table above, Fe-Mn-Si-N alloy exhibits unique comprehensive advantages in elastic modulus and elongation compared to Fe-Mn alloy, Fe-Mn-Si alloy, and Fe-Mn-N alloy.

[0074] Further analysis of the data in Tables 1 and 2 reveals that, with a constant Si content, the elastic modulus of the Fe-Mn-Si-N alloy exhibits a trend of first significantly increasing and then slowly decreasing with increasing N content, reaching an optimal value at an N content of 0.08%. With a constant N content, the elastic modulus of the Fe-Mn-Si-N alloy shows a parabolic trend with increasing Si content, reaching an optimal value at a Si content of 1%; however, with increasing N content, the influence of Si content becomes more pronounced, and the range increases rapidly.

[0075] Furthermore, with a fixed Si content, the elongation of the Fe-Mn-Si-N alloy exhibits a slight upward trend along a gentle parabola as the N content increases, reaching an optimal value at an N content of 0.08%. With a fixed N content, the elongation of the Fe-Mn-Si-N alloy shows a positive correlation with the increase in Si content, and higher ductility is beneficial for the compression and release of the support. However, with the increase in N, the influence of Si content becomes smaller and smaller, and the range decreases rapidly.

[0076] In summary, when the Si content is 1% and the N content is 0.08%, the synergistic effect of Si and N on improving the elastic modulus and elongation of Fe-Mn-Si-N alloy is significant, with the highest elastic modulus and elongation, and good compression-release effect of biliary stent graft.

[0077] Please see Figure 6 , Figure 7 Examples 1 and 4 exhibited significant corrosion activity characteristics, with their polarization current density reaching a maximum value and their open circuit potential shifting significantly negatively. This indicates that the synergistic effect of the ratio of 1Si-0.05N and 2Si-0.08N significantly enhances the corrosion driving force of the Fe-Mn-Si-N alloy, thereby greatly increasing the degradation rate of the Fe-Mn-Si-N alloy and achieving the goal of controllable degradation.

[0078] Please see Figure 8-16 ,Depend on Figure 8-13 Various embodiments and Figure 14-16 The electron micrographs of the comparison examples before and after corrosion (a and b) show that Example 6 has the best corrosion rate; after corrosion, the growth in Example 4 is evenly distributed and appears as a large-scale dotted distribution; Example 6 has the most growth and a wide distribution range.

[0079] Therefore, it can be seen that the present invention has the following beneficial effects compared with the prior art: 1) The Fe-Mn-Si-N alloy has excellent biodegradability and biocompatibility. Fe and Mn are both trace elements that are beneficial to the human body. Si is an important component of bones, teeth, hair and skin. N is a basic component of the human body. Even if C and Ti are added, Ti is physiologically inert to the human body. C is also a basic component of the human body. The scaffold material made of this alloy can be degraded in the body without toxic side effects. 2) By synergistically regulating Si and N in Fe-Mn-Si-N alloy, Fe-Mn-Si-N can effectively improve the elastic modulus and ductility of Fe-Mn-Zn-Si while meeting the requirements of CT / MRI imaging, and also ensure that the strength meets the requirements, thereby improving the elasticity, compression release effect and shape memory effect of the scaffold made of Fe-Mn-Zn-Si alloy. 3) By synergistically regulating Si and N in the Fe-Mn-Si-N alloy, the polarization current density is increased, which significantly enhances the corrosion driving force of the Fe-Mn-Si-N alloy, thereby greatly improving the degradation rate of the Fe-Mn-Si-N alloy and achieving controllable degradation.

[0080] This invention is not limited to the above-described embodiments. If any modifications or variations to this invention do not depart from the spirit and scope of this invention, and if such modifications and variations fall within the scope of the claims and equivalent technologies of this invention, then this invention also intends to include such modifications and variations.

Claims

1. An application of a biodegradable low-silicon iron-manganese alloy material, wherein the biodegradable low-silicon iron-manganese alloy material comprises Mn, Si, N, Fe, C, and Ti, characterized in that: S10: The raw materials pure iron, electrolytic Mn, MnN, Si, C and Ti are smelted into a block alloy; S20: The block alloy is homogenized by annealing under a set annealing temperature, annealing time and vacuum environment to obtain a biodegradable low silicon iron manganese alloy. The annealing temperature is 1000℃~1100℃ and the annealing time is 5 hours to 7 hours. S30: Biodegradable low-silicon iron-manganese alloy material is drawn into alloy wire. S40: The alloy wire is braided with a structural braiding pattern using a sine curve as the basic unit to obtain a self-expanding alloy bare support. S50: The self-expanding alloy bare stent is coated with a coating material; In the biodegradable low-silicon iron-manganese alloy, the mass percentage of Mn is 20%~30%, the mass percentage of Si is 1%~2%, the mass percentage of N is 0.05%~0.1%, the mass percentage of Ti is 0.05%~0.1%, the mass percentage of C is 0.05%~0.1%, and the balance is Fe.

2. The application of the biodegradable low-silicon iron-manganese alloy material according to claim 1, characterized in that, One or both ends of the self-expanding alloy bare support are not covered with a membrane.

3. The application of the biodegradable low-silicon iron-manganese alloy material according to claim 1, characterized in that, The coating material is PCL fiber prepared by electrospinning; the diameter of the PCL fiber is less than 100 nm; the parameters of the electrospinning are: voltage of 10KV~15KV, spinning distance of 20cm~30cm, and spinning solution concentration of 0.5g / mL~0.9g / mL.

4. The application of the biodegradable low-silicon iron-manganese alloy material according to claim 1, characterized in that, The raw materials smelted in step S10 have a purity of ≥99.9% for pure iron, electrolytic Mn, MnN, Si, C, and Ti.

5. The application of the biodegradable low-silicon iron-manganese alloy material according to claim 1, characterized in that, The vacuum level in the vacuum environment is 10. -3 ~10 -5 Pa.

6. A biodegradable TIPS scaffold, characterized in that, The biodegradable TIPS scaffold is obtained based on the application described in any one of claims 1-5.

7. A biodegradable biliary stent, characterized in that, The biodegradable biliary stent graft is obtained based on the application described in any one of claims 1-5.

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