Degradable biomedical zinc alloy and preparation method and application thereof

Abstract

The application belongs to the technical field of biomedical alloy materials, and particularly relates to a degradable biomedical zinc alloy material and a preparation method and application thereof. The degradable biomedical zinc alloy is composed of the following elements in percentage by weight: Cu: 1.0%~2.0%, Ag: 0.1%~2.0%, Zr: 0.1%~2.0%, and the balance is Zn. The application provides a preparation method for improving the strength and corrosion resistance of the degradable biomedical zinc alloy. The method is characterized by a cumulative accumulative roll bonding process and a subsequent recrystallization annealing process, so as to manufacture a layered bimodal structure material with alternating distribution of fine grains and coarse grains. The fine grains are strengthened by a back stress strengthening mechanism to give the material strength, and the coarse grains can provide necessary work hardening rate and uniform elongation rate, so that the strength and plasticity are synergistically improved. In addition, the annealing treatment can also improve the grain structure and grain boundary structure of the metal material, eliminate stress and deformation, reduce defects, and improve the corrosion resistance of the alloy.

Description

Technical Field

[0001] This invention belongs to the field of biomedical alloy materials technology, specifically relating to a biodegradable biomedical zinc alloy material, its preparation method, and its application. Background Technology

[0002] Cardiovascular disease has long been a threat to human health, ranking first among the most prevalent diseases globally, according to surveys. However, traditional implantable stents are permanent materials, and their long-term presence in the body increases the probability of readmissions and death, as well as placing a financial burden on patients. Therefore, considering long-term safety, the best solution for interventional vascular treatment is to design and fabricate a fully biodegradable stent device. Biodegradable metallic stents must maintain stable mechanical properties during their service life in the patient's body and gradually corrode and dissolve after 6-12 months. The basic conditions for their application are: yield strength > 200 MPa, tensile strength > 300 MPa, elongation at break > 15-18%, and a corrosion rate < 20 μm / year.

[0003] Currently, biodegradable metallic stent materials mainly include magnesium-based alloys, iron-based alloys, and zinc-based alloys. Among them, magnesium alloys have a relatively short service life and it is difficult to maintain the integrity of their mechanical properties; iron alloys have a slow degradation rate, and their ferromagnetism may cause compatibility issues with certain imaging devices (such as magnetic resonance imaging); while zinc has an electrode potential and chemical activity between the two, exhibiting suitable degradation performance. Zinc ions are an essential nutrient element for the human body and are rapidly transported in human tissues, thus producing virtually no cytotoxicity at the implantation site, ensuring good biocompatibility. Therefore, biodegradable zinc alloy stents are expected to become a typical representative of the next generation of biodegradable metallic vascular stents.

[0004] Pure zinc has poor mechanical properties, failing to meet clinical standards for biodegradable medical materials. Therefore, researchers both domestically and internationally have alloyed pure zinc and processed it using various techniques (such as hot rolling, cold drawing, and extrusion) in hopes of achieving satisfactory performance. Patent application CN112281027A discloses a biodegradable biomedical Zn-Cu-Ag-Zr zinc alloy and its preparation method. This method uses alloying and hot rolling to prepare the Zn-Cu-Ag-Zr zinc alloy, significantly improving its elongation and meeting usage standards. However, its strength and corrosion resistance still do not meet the requirements for biodegradable biomedical vascular stents, failing to achieve a synergistic improvement in strength and ductility. Therefore, developing a material with high strength and strong corrosion resistance is essential. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a biodegradable biomedical zinc alloy, its preparation method, and its application. Specifically, the following technical solution is adopted:

[0006] In one aspect, the present invention provides a biodegradable biomedical zinc alloy, wherein the alloy comprises the following elements by weight percentage: Cu: 1.0%~2.0%, Ag: 0.1%~2.0%, Zr: 0.1%~2.0%, with the balance being Zn.

[0007] The biodegradable biomedical zinc alloy of this invention has the following elemental composition: Cu: 1.0%~2.0%, Ag: 0.1%~2.0%, Zr: 0.1%~2.0%, with the balance being Zn. This weight percentage range of elements can improve the mechanical properties of the material while maintaining good biocompatibility.

[0008] Furthermore, the aforementioned biodegradable biomedical zinc alloy comprises the following elements by weight percentage: Cu: 1.5%, Ag: 0.5%, Zr: 0.1%, with the balance being Zn.

[0009] Furthermore, the above-mentioned biodegradable biomedical zinc alloy has a tensile strength of 217±6MPa, an elongation of 36.1±3%, and a corrosion rate of 0.0395±0.003mm / year.

[0010] A second aspect of the present invention also provides a method for preparing the above-mentioned biodegradable biomedical zinc alloy, comprising the following steps:

[0011] S1: The Zn-Cu-Ag-Zr alloy prepared by gravity casting is cut into plates with a thickness of 2 mm to 6 mm, and subjected to homogenization annealing at a temperature of 250℃ to 600℃. Then, the surface oxide layer is removed and the plate is cleaned with acetone to obtain the Zn-Cu-Ag-Zr alloy substrate.

[0012] S2: The Zn-Cu-Ag-Zr alloy substrate obtained in step S1 is subjected to a cumulative rolling process; in the cumulative rolling process, the rolling deformation is selected to be 40%~70%, the rolling temperature is 150℃~350℃, the rolling speed is 0.5m / s~1.5m / s, the number of rolling cycles is 2~6, and the rolling temperature is held for 20min during each rolling cycle to obtain the Zn-Cu-Ag-Zr alloy material;

[0013] S3: The Zn-Cu-Ag-Zr alloy material obtained in step 2 is annealed at a temperature of 150℃~400℃ for 5min~60min, and then quenched to room temperature to finally obtain a biodegradable biomedical zinc alloy.

[0014] This invention proposes a cumulative rolling large plastic deformation process and a recrystallization annealing process for processing Zn-Cu-Ag-Zr zinc alloy materials. On the one hand, compared with conventional rolling, where the strain is limited, cumulative rolling allows for repeated rolling, enabling the cumulative strain to reach its maximum value and breaking through the limitation of the reduction in conventional rolling, thus obtaining ultrafine-grained metal materials. Compared with surface plastic deformation processes (such as conventional rolling and ultrasonic rolling), where plastic deformation only acts on the surface, in each cycle of the cumulative rolling process, half of the surface enters the thickness center, and the entire thickness area of ​​the high-pass cumulatively rolled plate can generate huge strain. On the other hand, after recrystallization annealing, the material forms a layered bimodal microstructure. Fine grains impart strength to the material through the back stress strengthening mechanism, while coarse grains provide the necessary work hardening rate and uniform elongation, thereby achieving a synergistic improvement in strength and plasticity. Annealing treatment can also improve the grain structure and grain boundary structure of the metal material, eliminate stress and deformation, reduce defects, and improve the corrosion resistance of the alloy.

[0015] Furthermore, in step S1 above, the thickness of the plate is 3mm, and the temperature of the homogenization annealing treatment is 350℃.

[0016] Furthermore, in step S2 above, during the cumulative rolling process, the rolling deformation is 50%, the rolling temperature is 300℃, the rolling speed is 1m / s, and the number of rolling cycles is 3. Additionally, during each cumulative rolling cycle, the surface oxide layer needs to be removed and the material cleaned with acetone. The range of rolling deformation is crucial: too low a deformation will result in insufficient grain refinement, affecting performance and surface quality; too high a deformation will cause cracking or failure; too low a rolling temperature will result in insufficient viscosity during rolling, preventing the material from being rolled together; too high a temperature will affect the internal structure of the material, thus impacting its properties.

[0017] Furthermore, in step S3 above, the annealing temperature is 150°C and the annealing time is 30 min. An annealing temperature of 150°C allows the material to recrystallize, further refining the grain size; an annealing time of 30 min allows the material to recrystallize completely. If the annealing temperature is too high or too low, or the annealing time is too long or too short, it will affect the crystallization of the material, resulting in poor material performance.

[0018] A third aspect of the present invention also provides the use of the above-mentioned biodegradable biomedical zinc alloy in the preparation of biodegradable medical implants. The biodegradable medical implants include bone screws, bone plates, cardiovascular stents, anastomotic devices, sutures, intestinal stents, biliary stents, fixation needles, and intramedullary nails.

[0019] The beneficial effects of this invention are as follows: This invention proposes a process method to improve the strength and corrosion resistance of biodegradable biomedical Zn-Cu-Ag-Zr zinc alloys. Through cumulative rolling and subsequent recrystallization annealing, a layered bimodal structure material with alternating fine and coarse grains is manufactured. The fine grains impart strength to the material through the back stress strengthening mechanism, while the coarse grains provide the necessary work hardening rate and uniform elongation, thereby achieving a synergistic improvement in strength and plasticity. Annealing treatment can also improve the grain structure and grain boundary structure of the metallic material, eliminate stress and deformation, reduce defects, and improve the corrosion resistance of the alloy. Attached Figure Description

[0020] Figure 1 The image shown is a metallographic image of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in the as-cast state in Example 1;

[0021] Figure 2 The image shown is a metallographic diagram of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in Example 1 after cumulative roll annealing;

[0022] Figure 3 The figure shows the mechanical properties of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in Example 1 in the as-cast state and after cumulative roll annealing.

[0023] Figure 4 The image shown is a diagram of the electrochemical corrosion morphology of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in the as-cast state in Example 1.

[0024] Figure 5 The image shown is an electrochemical corrosion morphology diagram of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in Example 1 after cumulative roll annealing.

[0025] Figure 6 The figure shows the dynamic polarization curves of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in Example 1 in the as-cast state and after cumulative rolling annealing. Detailed Implementation

[0026] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] In this document, unless otherwise stated, the term "%" means "mass %"; the term "μg / mL" means micrograms per milliliter. In this document, unless otherwise stated, the term "%" refers to the total weight of the compositions of this application.

[0029] In this article, the term "all ranges" refers to both each specific range within a given range and combinations of subranges between given ranges. For example, the range 1–5 specifically includes 1, 2, 3, 4, and 5, and also includes subranges such as 2–5, 3–5, 2–3, 2–4, and 1–4.

[0030] Example 1

[0031] This embodiment is a biodegradable biomedical Zn-Cu-Ag-Zr alloy with the following elemental mass fractions: Cu: 1.5%, Ag: 0.5%, Zr: 0.1%, and the balance being Zn.

[0032] The preparation method of the biodegradable biomedical zinc alloy in this embodiment includes the following steps:

[0033] Step 1: Gravity casting yields a Zn-1.5Cu-0.5Ag-0.1Zr alloy, with the following mass percentages: Cu: 1.5%, Ag: 0.5%, Zr: 0.1%, and the balance being Zn. This alloy is then prepared into a 3mm thick plate and subjected to homogenization annealing at 350℃. It is then sanded to 2000# grit and polished to obtain the Zn-1.5Cu-0.5Ag-0.1Zr alloy substrate.

[0034] Step 2: The Zn-1.5Cu-0.5Ag-0.1Zr alloy substrate obtained in Step 1 is subjected to a cumulative rolling process. The deformation is selected as 50%, the number of rolling cycles is 3, the rolling temperature is 300℃, and the rolling speed is 1m / s. Note that after each rolling cycle, it is necessary to hold at 300℃ for 20min. After each rolling cycle, the surface oxide layer needs to be removed and the substrate cleaned with acetone.

[0035] Step 3: Anneal the Zn-1.5Cu-0.5Ag-0.1Zr alloy treated in Step 2 at a temperature of 150℃ for 30 minutes, followed by water quenching to room temperature to obtain a biodegradable biomedical Zn-1.5Cu-0.5Ag-0.1Zr alloy with a layered bimodal structure.

[0036] The following are the relevant tests performed on the materials obtained in the above embodiments, as detailed below:

[0037] Figure 1 The image shown is a metallographic diagram of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in its as-cast state. Figure 2 The image shown is a metallographic diagram of a Zn-1.5Cu-0.5Ag-0.1Zr alloy after cumulative roll annealing. Figure 3 The figures shown are mechanical property diagrams of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in Example 1, in the as-cast state and after cumulative roll annealing; Figure 1 and Figure 2 It can be seen that the Zn-Cu-Ag-Zr zinc alloy, through cumulative rolling and recrystallization annealing processes, yields a layered bimodal structure with alternating fine and coarse grains, and the second phase also exhibits a layered distribution. These processes complete the preparation of the layered bimodal structure of the Zn-Cu-Ag-Zr zinc alloy. Figure 3 It can be seen that the mechanical properties of the cumulative rolled annealed material are improved compared with those of the cast material. The elongation is increased by 980.84% ​​to 36.16%, which meets the implantation standard; the tensile strength is increased by 96.65% to 217.66 MPa.

[0038] Figure 4 The image shows the electrochemical corrosion morphology of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in its as-cast state. Figure 5 The image shows the electrochemical corrosion morphology of the Zn-1.5Cu-0.5Ag-0.1Zr alloy after cumulative roll annealing. Figure 6 The figure shows the dynamic polarization curves of the Zn-1.5Cu-0.5Ag-0.1Zr alloy in Example 1 in the as-cast state and after cumulative rolling annealing; from Figure 4 , Figure 5 and Figure 6 It can be seen that the corrosion resistance of the layered bimodal zinc alloy obtained after cumulative rolling annealing is also improved. The corrosion resistance of the cast material is 144.7 μm / year, and the corrosion resistance of the cumulative rolling annealed material is 39.53 μm / year, which is an improvement of 72.68%, close to the standard for biomaterial implantation.

[0039] Example 2

[0040] A method for preparing a biodegradable biomedical Zn-2.0Cu-1.0Ag-0.3Zr alloy specifically includes the following steps:

[0041] Step 1: Gravity casting yields a Zn-2.0Cu-1.0Ag-0.3Zr alloy with a mass percentage of Cu: 2.0%, Ag: 1.0%, Zr: 0.3%, and the balance being Zn. This alloy is then prepared into a 4mm thick plate, subjected to homogenization annealing at 350℃, sanded to 2000# grit, and polished to obtain the Zn-2.0Cu-1.0Ag-0.3Zr alloy substrate.

[0042] Step 2: The Zn-2.0Cu-1.0Ag-0.3Zr alloy substrate obtained in Step 1 is subjected to a cumulative rolling process. The deformation is selected as 50%, the number of rolling cycles is 4, the rolling temperature is 280℃, and the rolling speed is 1m / s. Note that after each rolling cycle, it is necessary to hold at 280℃ for 20min. After each rolling cycle, the surface oxide layer needs to be removed and the substrate cleaned with acetone.

[0043] Step 3: Anneal the Zn-2.0Cu-1.0Ag-0.3Zr alloy treated in Step 2 at a temperature of 180℃ for 20 minutes, followed by water quenching to room temperature to obtain a biodegradable biomedical Zn-2.0Cu-1.0Ag-0.3Zr alloy with a bimodal structure.

[0044] Example 3

[0045] A method for preparing a biodegradable biomedical Zn-1.3Cu-0.8Ag-0.5Zr alloy for human use, specifically including the following steps:

[0046] Step 1: Gravity casting yields a Zn-1.3Cu-0.8Ag-0.5Zr alloy with a mass percentage of Cu: 1.3%, Ag: 0.8%, Zr: 0.5%, and the balance being Zn. This alloy is then prepared into a 5mm thick plate and subjected to homogenization annealing at 400℃. It is then sanded to 2000# grit and polished to obtain the Zn-1.3Cu-0.8Ag-0.5Zr alloy substrate.

[0047] Step 2: The Zn-1.3Cu-0.8Ag-0.5Zr alloy substrate obtained in Step 2 is subjected to a cumulative rolling process. The deformation is selected as 50%, the number of rolling cycles is 2, the rolling temperature is 250℃, and the rolling speed is 1m / s. Note that after each rolling cycle, it is necessary to hold at 250℃ for 20min. After each rolling cycle, the surface oxide layer needs to be removed and the substrate cleaned with acetone.

[0048] Step 3: Anneal the Zn-1.3Cu-0.8Ag-0.5Zr treated in Step 2 at a temperature of 250℃ for 10 minutes, and then quench it in water to room temperature to obtain a biodegradable biomedical Zn-1.3Cu-0.8Ag-0.5Zr alloy with a layered bimodal structure.

[0049] Example 4

[0050] Step 1: Gravity casting yields a Zn-1.8Cu-1.5Ag-0.8Zr alloy with a mass percentage of Cu: 1.8%, Ag: 1.5%, Zr: 0.8%, and the balance being Zn. This alloy is then prepared into a 6mm thick plate and subjected to homogenization annealing at 400℃. It is then sanded to 2000# grit and polished to obtain the Zn-1.8Cu-1.5Ag-0.8Zr alloy substrate.

[0051] Step 2: The Zn-1.8Cu-1.5Ag-0.8Zr alloy substrate obtained in Step 1 is subjected to a cumulative rolling process. The deformation is set at 50%, the number of rolling cycles is 3, the rolling temperature is 250℃, and the rolling speed is 1m / s. Note that after each rolling cycle, the substrate needs to be held at 250℃ for 20min; after each rolling cycle, the surface oxide layer needs to be removed and the substrate cleaned with acetone.

[0052] Step 3: Anneal the Zn-1.8Cu-0.5Ag-0.3Zr alloy treated in Step 2 at a temperature of 300℃ for 15 minutes, followed by water quenching to room temperature to obtain a Zn-1.8Cu-1.5Ag-0.8Zr alloy with a layered bimodal junction.

[0053] Although the description of the invention has been quite detailed and particularly of several described embodiments, it is not intended to limit it to any of these details or embodiments or any particular embodiment, but should be considered as providing a broad possible interpretation of the claims by referring to the appended claims and taking into account the prior art, thereby effectively covering the intended scope of the invention. Furthermore, the invention has been described above with respect to embodiments foreseeable by the inventors in order to provide a useful description, and non-substantial modifications to the invention that have not yet been foreseen may still represent equivalent modifications.

Claims

1. A method for preparing a biodegradable biomedical zinc alloy, characterized in that, Includes the following steps: S1: The Zn-Cu-Ag-Zr alloy prepared by gravity casting is cut into plates with a thickness of 2 mm to 6 mm, and subjected to homogenization annealing at a temperature of 250℃ to 600℃. Then, the surface oxide layer is removed and the plate is cleaned with acetone to obtain the Zn-Cu-Ag-Zr alloy substrate. S2: The Zn-Cu-Ag-Zr alloy substrate obtained in step S1 is subjected to a cumulative rolling process; in the cumulative rolling process, the rolling deformation is selected to be 40%~70%, the rolling temperature is 150℃~350℃, the rolling speed is 0.5m / s~1.5m / s, the number of rolling cycles is 2~6, and the rolling temperature is held for 20 minutes after each rolling to obtain the Zn-Cu-Ag-Zr alloy material; S3: The Zn-Cu-Ag-Zr alloy material obtained in step S2 is annealed at a temperature of 150℃~400℃ for 5min~60min, and then quenched to room temperature to finally obtain a biodegradable biomedical zinc alloy. The biodegradable biomedical zinc alloy comprises, by weight percentage, the following elements: Cu: 1.0%~2.0%, Ag: 0.1%~2.0%, Zr: 0.1%~2.0%, with the balance being Zn; The biodegradable biomedical zinc alloy has a tensile strength of 217±6MPa, an elongation of 36.1±3%, and a corrosion rate of 0.0395±0.003mm / year.

2. The preparation method according to claim 1, characterized in that, In step S1, the thickness of the sheet material is 3mm, and the homogenization annealing temperature is 350℃.

3. The preparation method according to claim 1, characterized in that, In step S2, during the cumulative rolling process, the rolling deformation is 50%, the rolling temperature is 300℃, the rolling speed is 1m / s, and the number of rolling cycles is 3.

4. The preparation method according to claim 3, characterized in that, During the cumulative rolling process, the surface oxide layer needs to be removed and the surface cleaned with acetone after each rolling cycle.

5. The preparation method according to claim 1, characterized in that, In step S3, the annealing temperature is 150℃ and the annealing time is 30min.

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