Medical Mg-Zn-Mn alloy material and preparation method and application thereof

Abstract

The invention relates to a medical Mg-Zn-Mn alloy material and a preparation method thereof, and the medical Mg-Zn-Mn alloy material comprises the following components in percentage by weight: 1% of Zn, 0.4-0.8% of Mn, 1.25-2.5% of Zn / Mn, and the balance of Mg. Raw materials including pure Mg, pure Zn and an Mg-3% Mn intermediate alloy are smelted, mixed and subjected to water cooling to obtain a cast ingot, the cast ingot is subjected to solid solution treatment and then subjected to water cooling, the biodegradable Mg-Zn-Mn alloy bar is obtained through extrusion, it is detected that the average grain size of the material is smaller than or equal to 7 micrometers, and galvanic corrosion caused by a second phase is reduced due to the fact that the Zn element is completely dissolved into a matrix in a solid solution mode; the invention also relates to an application of the medical Mg-Zn-Mn alloy material in preparation of an orbital bone repair material, the Mg-Zn-Mn alloy material prepared by the invention is directly processed into a nail plate and a matched screw conforming to an orbital bone structure, and in vitro experiments show that the corrosion rate is 0.27-0.37 mm / y, the tensile strength is 255-287 MPa, and the yield strength is 178-225 MPa; in-vivo experiments show that the material is relatively good in biocompatibility, uniform in degradation and stable in structure, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of medical metal materials technology, and in particular to a medical Mg-Zn-Mn alloy material, its preparation method and application. Background Technology

[0002] The orbital bone is a crucial structure that forms the contours of the human face and protects the eyeball; its morphology is complex. Orbital bone fractures are a common and challenging type of bone injury in the craniofacial region. Due to the unique anatomy of this area, bone fragments are typically small and thin, surrounded by important nerves and blood vessels, thus placing extremely high demands on fixation materials and techniques. Currently, internal fixation treatment for such fractures in clinical practice mainly relies on metal plate and screw systems, surgically reducing and fixing the fracture ends to promote successful bone healing.

[0003] In this field, the most widely used internal fixation materials are medical titanium alloys and related alloys. These materials possess excellent mechanical properties; their strength, stiffness, and toughness are sufficient to meet the stability requirements during fixation. However, as a bioinert metal, titanium alloys hardly degrade in the human physiological environment and remain in the body as permanent implants. This brings several significant problems: First, permanent implants may become potential stress shielding sources, hindering the normal mechanical load on the underlying bone in the long term, leading to local bone resorption and bone loss; second, for the orbit, a thin-walled bone region, the indestructible titanium plate may interfere with subsequent medical imaging examinations, such as CT or MRI; furthermore, for some sensitive patients or pediatric patients, there is a possibility of needing a second surgery to remove it, which not only increases the patient's economic and psychological burden but also brings additional surgical trauma and infection risks.

[0004] To overcome the inherent defects of non-degradable materials, bioabsorbable polymer materials, such as polylactic acid (PLA) and polyglycolic acid (PGA), have been developed and applied clinically. The greatest advantage of these materials is their ability to gradually degrade in vivo through hydrolysis and ultimately be metabolized and absorbed by the body, thus avoiding the need for secondary removal surgery. However, polymer materials also have significant limitations. The core problem lies in their generally insufficient mechanical strength, particularly their initial stiffness and load-bearing capacity, which are often lower than cortical bone. Under the stress generated by chewing or facial movements, they may creep or fracture, leading to fixation failure. Furthermore, their degradation process is difficult to precisely control, and the degradation products are often acidic, easily accumulating locally and triggering aseptic inflammatory reactions. Simultaneously, the rate of mechanical property decay during degradation does not match the rate of bone healing, creating a window of fixation failure.

[0005] In recent years, biodegradable metallic materials, especially magnesium alloys, have brought new hope to this field. Magnesium alloys have a density close to that of human bone, effectively avoiding stress shielding effects. Their elastic modulus is also much lower than that of titanium alloys, more closely resembling natural bone, which is beneficial for bone mechanical conduction and healing. Most importantly, magnesium alloys can undergo controlled corrosion degradation in physiological environments and be metabolized by the body, ultimately disappearing completely and avoiding permanent retention or secondary surgery. Magnesium ions, as an essential trace element for the human body, play an active role in bone integration and metabolism. However, directly applying traditional magnesium alloys to the harsh environment of the orbital bone still faces significant challenges. The main bottleneck lies in the excessively rapid degradation rate; in the presence of chloride ions in bodily fluids, they corrode rapidly, causing the implant to prematurely lose its mechanical integrity and fail to provide sufficient support for fracture healing. Simultaneously, excessively rapid degradation is accompanied by the release of large amounts of hydrogen gas, which may form air cavities around the thin orbital tissue, affecting healing. Furthermore, some traditional cast magnesium alloys contain impurities or microscopic defects, which can exacerbate local corrosion and potentially cause biocompatibility issues. Therefore, developing a novel magnesium alloy that combines high initial mechanical properties, controllable degradation rate, and excellent biocompatibility, specifically for manufacturing orbital bone fixation plate systems, has become a crucial and urgently needed technological direction in the field of biomaterials. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a medical Mg-Zn-Mn alloy material, its preparation method, and its applications.

[0007] The technical solution of this invention is as follows: A medical Mg-Zn-Mn alloy material comprises the following raw material components: by weight percentage, Zn 1%, Mn 0.4-0.8%, Zn / Mn ratio 1.25-2.5, and the balance being Mg and unavoidable impurities.

[0008] Furthermore, the average grain size of the medical Mg-Zn-Mn alloy material is ≤7μm.

[0009] The preparation method of the medical Mg-Zn-Mn alloy material includes the following steps: melting, mixing and water-cooling the raw materials pure Mg, pure Zn and Mg-3%Mn master alloy to obtain an ingot, water-cooling the ingot after solution treatment, and extruding to obtain a biodegradable Mg-Zn-Mn alloy rod.

[0010] Furthermore, the melting temperature is 720-740℃.

[0011] Furthermore, the technical parameters for the solution treatment are: solution treatment at 400-420℃ for 12 hours.

[0012] Furthermore, the technical parameters of the extrusion are: temperature of 260-300℃ and extrusion ratio of (20-28):1.

[0013] Application of the medical Mg-Zn-Mn alloy material prepared by the above method in the preparation of orbital bone repair materials.

[0014] Compared with the prior art, the present invention has at least the following advantages: 1. This invention relates to a medical Mg-Zn-Mn alloy material and its preparation method. The medical Mg-Zn-Mn alloy material, by weight percentage, contains 1% Zn, 0.4-0.8% Mn, a Zn / Mn ratio of 1.25-2.5, and the balance is Mg. The raw materials, pure Mg, pure Zn, and Mg-3%Mn master alloy, are melted, mixed, and water-cooled to obtain an ingot. The ingot is then solution-treated, water-cooled, and extruded to obtain a biodegradable Mg-Zn-Mn alloy rod. The material is tested to have an average grain size ≤7μm, wherein the Zn element is completely dissolved in the matrix, reducing galvanic corrosion caused by the second phase.

[0015] 2. This invention also relates to the application of the aforementioned medical Mg-Zn-Mn alloy material in the preparation of orbital bone repair materials. The Mg-Zn-Mn alloy material prepared by this invention is directly processed into nail plates and matching screws that conform to the orbital bone structure. In vitro experiments show that the corrosion rate is 0.27-0.39 mm / y, the tensile strength is 255-287 MPa, and the yield strength is 178-225 MPa. In vivo experiments show that the material has good biocompatibility, uniform degradation, and stable structure, and has broad application prospects. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0017] Figure 1 The image shows the morphology of the medical Mg-Zn-Mn alloy material prepared in Example 1 of this invention. Figure 2 The XRD patterns of the medical Mg-Zn-Mn alloy materials prepared in Examples 1 and 2 and Comparative Example 1 of this invention are shown below. Figure 3 X-ray images of the orbital bone plate structure implanted in the body at 3, 5, and 12 weeks; Figure 4 SEM image of the orbital bone plate structure after removal 3 months after implantation. Detailed Implementation

[0018] The present invention will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above application content.

[0019] This invention provides a general and / or specific description of the materials and experimental methods used in the experiments. Unless otherwise specified, all experimental or testing methods are conventional methods; all reagents or instruments used, unless otherwise specified, are commercially available conventional products prepared or used using conventional methods.

[0020] This invention relates to magnesium ingots with a purity of ≥99.98% and zinc granules with a purity of ≥99.9%.

[0021] Example 1: Preparation method of medical Mg-Zn-Mn alloy material S1. Using high-purity Mg ingots, high-purity Zn particles and Mg-3%Mn master alloy as raw materials, the raw materials are weighed and batched according to the following mass percentage content: Zn 1%, Mn 0.4% (Zn / Mn is 2.5), with the balance being Mg and unavoidable impurities. S2. Under the protective atmosphere of CO2+SF6 mixed gas (volume ratio of 99:1), pure Mg is melted at a temperature of 720℃. After the pure Mg melts, preheated pure Zn and Mg-3%Mn master alloy are added. After all the solid metals have melted, the mixture is stirred to ensure that the alloy elements in the crucible are evenly distributed. The floating residue is removed, and the mixture is allowed to stand for 15 minutes before water cooling. After the ingot cools, the magnesium alloy ingot is removed, machined, and then processed. S3. The magnesium alloy ingot obtained in step S2 is solution treated at 400℃ for 12 hours and then water cooled. The ingot is then extruded at an extrusion ratio of 28:1 and an extrusion temperature of 300℃ to obtain a bar.

[0022] Example 2: Preparation method of medical Mg-Zn-Mn alloy material S1. Using high-purity Mg ingots, high-purity Zn particles and Mg-3%Mn master alloy as raw materials, the raw materials are weighed and batched according to the mass percentage content of Zn 1%, Mn 0.8% (Zn / Mn is 1.25), with the balance being Mg and unavoidable impurities. S2. Under the protective atmosphere of CO2+SF6 mixed gas (volume ratio of 99:1), pure Mg is melted at a temperature of 720℃. After the pure Mg melts, preheated pure Zn and Mg-3%Mn master alloy are added. After all the solid metals have melted, the mixture is stirred to ensure that the alloy elements in the crucible are evenly distributed. The floating residue is removed, and the mixture is allowed to stand for 15 minutes before water cooling. After the ingot cools, the magnesium alloy ingot is removed, machined, and then processed. S3. The magnesium alloy ingot obtained in step S2 is solution treated at 400℃ for 12 hours and then water cooled. The ingot is then extruded at an extrusion ratio of 25:1 and an extrusion temperature of 300℃ to obtain a bar.

[0023] Comparative Example 1 The difference between this comparative example and Example 2 lies in the preparation method: the weight percentage of Zn is 1%, and no Mn element is added. The remaining steps are the same, and the specific operation is as follows: S1. Using high-purity Mg ingots and high-purity Zn granules as raw materials, the raw materials are weighed and batched according to the mass percentage content of Zn 1% and the balance being Mg and unavoidable impurities. S2. Under the protective atmosphere of CO2+SF6 mixed gas (volume ratio of 99:1), pure Mg is melted at a temperature of 720℃. After the pure Mg melts, preheated pure Zn is added. After all the solid metals have melted, the mixture is stirred to ensure that the alloying elements in the crucible are evenly distributed. The floating residue is removed, and the mixture is allowed to stand for 15 minutes before water cooling. After the ingot cools, the magnesium alloy ingot is removed, machined, and then processed. S3. The magnesium alloy ingot obtained in step S2 is solution treated at 400℃ for 12 hours and then water cooled. The ingot is then extruded at an extrusion ratio of 25:1 and an extrusion temperature of 300℃ to obtain a bar.

[0024] Performance testing The Mg-Zn-Mn alloy materials prepared in Examples 1 and 2 and Comparative Example 1 were subjected to performance tests. The mechanical properties were tested according to GB / T 1177-2018; the degradation rate was tested according to ISO 10993-15:2019, and the materials were immersed in SBF solution at 37°C for 7 days. The specific results are shown in Table 1.

[0025] Table 1 Properties of alloy materials prepared in Examples 1-2 and Comparative Example 1 As shown in Table 1, compared to Comparative Example 1, the medical Mg-Zn-Mn alloy materials prepared in the examples achieved significant grain refinement through the addition of Mn. The average grain size decreased significantly from 20.62 μm in Comparative Example 1 (Mg-1Zn) to 6.97 μm and 4.18 μm, respectively, indicating that Mn effectively promoted grain nucleation and inhibited grain growth in the alloy, resulting in a finer and more uniform microstructure. Grain refinement significantly improved the mechanical properties of the material: the tensile strengths of Examples 1 and 2 were 255 MPa and 287 MPa, respectively, and the yield strengths were 178 MPa and 225 MPa, respectively, both significantly higher than those of Comparative Example 1 (tensile strength 234 MPa, yield strength 158 MPa). Meanwhile, the elongation remained at a high level (19.3–20.9%), demonstrating a good balance between strength and ductility.

[0026] Regarding corrosion resistance, the in vitro corrosion rates of Examples 1 and 2 were 0.27 mm / y and 0.39 mm / y, respectively, both comparable to or slightly improved from Comparative Example 1 (0.29 mm / y). This indicates that the biodegradability of the material was not adversely affected while maintaining good mechanical properties. Overall, without the introduction of rare earth elements, a good balance between mechanical properties and degradation rate can be achieved by adjusting the Mn content and process parameters.

[0027] In contrast, Comparative Example 1, lacking the addition of Mn, exhibited significantly larger grain sizes (20.62 μm), resulting in lower yield strength and tensile strength, and ultimately, poorer overall performance. This demonstrates that the introduction of Mn plays a crucial role in refining the microstructure and improving the mechanical properties of Mg-Zn alloys, providing an effective approach for the optimized design of biodegradable magnesium alloys for medical applications.

[0028] Application examples This invention uses the medical Mg-Zn-Mn alloy material (Mg-1Zn-0.4Mn) prepared in Example 1 as an example. This alloy was precision-machined into an orbital bone plate system and implanted into rabbits. X-ray imaging was performed at weeks 3, 5, and 12 post-surgery, and the results are as follows: Figure 3 As shown; the experimental animals were euthanized and the implants were removed 3 months after implantation. The average corrosion rate during implantation, calculated using the weightlessness method, was approximately 0.34 mm / y, as shown in the figure. Figure 4 As shown.

[0029] During implantation, all experimental animals exhibited good health, stable weight gain, and normal activity. Surgical incisions healed well without significant redness, swelling, exudation, purulent discharge, or conjunctival hemorrhage. No signs of infection or immune rejection were observed. Both alloy plate systems maintained their overall shape without breakage even after prolonged implantation, indicating a relatively uniform degradation process and structural stability.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A medical Mg-Zn-Mn alloy material, characterized by, The raw material components include the following: Zn 1%, Mn 0.4-0.8%, Zn / Mn is 1.25-2.5, the balance is Mg and inevitable impurities.

2. The medical Mg-Zn-Mn alloy material according to claim 1, characterized in that, The average grain size of the medical Mg-Zn-Mn alloy material is less than or equal to 7 microns.

3. The production method of the medical Mg-Zn-Mn alloy material according to any one of claims 1 to 2, characterized by, The method comprises the following steps: The raw materials pure Mg, pure Zn and Mg-3% Mn intermediate alloy are melted, mixed and water-cooled to obtain a cast ingot, the cast ingot is solid solution treated and water-cooled, and then extruded to obtain a biodegradable Mg-Zn-Mn alloy rod.

4. The production method according to claim 3, characterized by, The melting temperature is 720-740 DEG C.

5. The production method according to claim 4, characterized by, The technical parameters of the solid solution treatment are: solid solution treatment at 400-420 DEG C for 12 hours.

6. The preparation method according to claim 3, characterized in that, The technical parameters of the extrusion are: temperature is 260-300 DEG C, and the extrusion ratio is (20-28):

1.

7. The application of the medical Mg-Zn-Mn alloy material prepared by the preparation method in claim 3-6 in the preparation of an orbital bone repair material.

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