Medical zinc alloy with corrosion resistance and preparation method and application thereof

Abstract

This invention relates to the field of zinc alloy surface modification technology, and particularly to a corrosion-resistant medical zinc alloy, its preparation method, and its applications. The preparation method includes the following steps: weighing raw materials according to the chemical composition of the zinc alloy; cleaning the surface of the raw materials; smelting, refining, and casting to obtain an ingot; subjecting the ingot to equal-channel angular extrusion deformation to obtain an extruded zinc alloy; performing high-energy ion implantation on the zinc alloy to obtain a nitrogen-ion-implanted zinc alloy; and preparing a coating on the surface of the nitrogen-ion-implanted zinc alloy to obtain the final product. This invention achieves a high-adhesion, dense, and uniform deposition effect on the alloy surface through the synergistic control of "equal-channel angular extrusion + high-energy nitrogen ion implantation + biomimetic coating deposition," solving the problem of severe galvanic corrosion at localized sites in existing zinc alloys under corrosive environments. Simultaneously, the dense deposition layer helps inhibit rapid dissolution of the zinc alloy surface, significantly reducing the corrosion rate of the zinc alloy in corrosive environments.

Description

Technical Field

[0001] This invention relates to the field of zinc alloy surface modification technology, and in particular to a corrosion-resistant medical zinc alloy surface, its preparation method, and its application. Background Technology

[0002] With advancements in clinical medical technology, biodegradable zinc alloys for medical use have become an important research direction for orthopedic and cardiovascular implant devices. However, pure zinc and zinc alloys still face a series of technical challenges in practical applications, such as the corrosion process of Zn. 2+ Excessive local release concentration can trigger cytotoxicity or inflammatory reactions; on the other hand, it is prone to non-uniform corrosion, leading to a significant decline in the mechanical properties of the implant, and even sudden breakage without warning. Therefore, optimizing the corrosion behavior of zinc alloys and controlling their degradation rate have become key measures to promote the clinical application of zinc alloys.

[0003] Existing patent CN202310427212.7 describes coating preparation by optimizing the composition of the conversion solution, simplifying the formulation design and providing a relatively concise preparation approach for the surface modification of medical zinc alloys. This technology still has potential for improvement in the synergistic optimization of key process parameters such as pH control, stirring rate, and component addition. Another patent, CN202010028576.4, addresses some of the problems of insufficient corrosion resistance and limited bioactivity in traditional medical metal coatings, better meeting the core needs of biological tissue repair and replacement. However, it still suffers from high equipment costs, complex processes, and low mass production efficiency. Summary of the Invention

[0004] This invention provides a method for preparing a corrosion-resistant medical zinc alloy, solving the problems of uneven corrosion and severe galvanic corrosion at localized sites in corrosive environments in existing medical zinc alloys. This invention achieves a highly adhesive and dense, uniform deposition layer on the alloy surface through a synergistic control of "equal-channel angular extrusion + high-energy nitrogen ion implantation + biomimetic surface coating deposition," thus resolving the severe galvanic corrosion at localized sites in existing zinc alloys under corrosive conditions. Simultaneously, the dense deposition layer helps inhibit rapid dissolution of the zinc alloy surface, significantly reducing the corrosion rate of the zinc alloy in corrosive environments.

[0005] The technical solution of the present invention is as follows: In a first aspect, this invention provides a method for preparing a corrosion-resistant medical zinc alloy, comprising the following steps: According to the chemical composition of the zinc alloy, the raw materials are weighed, the surface of the raw materials is cleaned, and then smelted, refined and cast to obtain ingots; The ingot is subjected to equal-channel angular extrusion deformation to obtain an extruded zinc alloy; The zinc alloy was subjected to high-energy ion implantation to obtain a nitrogen-ion-implanted zinc alloy; A coating is prepared on the surface of the nitrogen-ion-implanted zinc alloy to obtain the zinc alloy.

[0006] In a preferred embodiment of the present invention, the raw materials include Zn ingots, Cu ingots, and Sr-containing master alloys and Dy-containing master alloys.

[0007] More preferably, the purity of the Cu ingot is ≥99.99%, the master alloy of Sr is Zn-5%Sr (where the mass fraction of Sr is 5%), and the master alloy of Dy is Zn-5%Dy (where the mass fraction of Dy is 5%).

[0008] More preferably, the zinc alloy is composed of the following raw materials by mass fraction: Dy 0.01%~0.05%, Sr 0.05%~0.15%, Cu 0.01%~0.03%, with the balance being Zn.

[0009] In a preferred embodiment of the present invention, the melting temperature is 480℃~520℃ and the melting time is 30 min~40 min; The refining agent used in the refining process is zinc chloride, and the amount of the refining agent added is 0.3% to 0.8% based on the total weight of the zinc alloy system. The casting temperature is 440℃~480℃, and the mold preheating temperature is 180℃~200℃.

[0010] In a preferred embodiment of the present invention, the extrusion angle of the equal channel corner extrusion deformation is 105°~120°, and multiple extrusions are performed by rotating 90° around the long axis after each extrusion.

[0011] More preferably, the extrusion temperature of the equal channel corner extrusion deformation is 250℃~310℃, the extrusion speed is 5 mm / s~15 mm / s, the number of extrusion passes is 2~6, and a hydrostatic pressure of 0~10 MPa is applied at the outlet end.

[0012] More preferably, air cooling or water mist cooling is used after extrusion to prevent deformation or grain growth.

[0013] In a preferred embodiment of the present invention, the high-energy nitrogen ion implantation has an implantation energy of 25-30 keV and a nitrogen ion implantation dose of 1×10⁻⁶. 17 ~2×10 17 cm -2 .

[0014] More preferably, the high-energy nitrogen ion implantation beam current density is 15~20 μA / cm², and the workpiece is subjected to argon ion sputtering cleaning treatment before nitrogen ion implantation, with a sputtering time of 6 min~10 min; the nitrogen ion injection angle is 0~15°, the implantation time is 1.5~3 h, and the vacuum degree is 1×10⁻⁶. -3 Pa.

[0015] More preferably, the workpiece surface is machined by turning 0.2 to 0.6 mm before ion implantation.

[0016] In a preferred embodiment of the present invention, the coating preparation involves depositing a biomimetic coating on the surface of a zinc alloy via nitrogen ion implantation. The biomimetic deposition solution used for the biomimetic coating deposition has a Ca / P ratio of 1.60 to 1.67, a pH value of 7.4 to 7.8, and a conversion temperature of 37℃ ± 1℃.

[0017] More preferably, the biomimetic deposition solution comprises a calcium salt and a phosphate, wherein the calcium salt is calcium nitrate and the phosphate is ammonium dihydrogen phosphate. More preferably, the alloy surface is subjected to an alkaline washing and activation treatment before depositing the coating.

[0018] More preferably, the alkaline washing and activation treatment uses a 5%~7% NaOH solution and is performed at 40℃~60℃ for 2~4 min. More preferably, the reaction time for the deposited coating is 4~6 hours.

[0019] In a second aspect, the present invention provides a zinc alloy prepared according to the above method.

[0020] In a third aspect, the present invention provides an application of the zinc alloy described above in medical implantable devices.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention solves the problem of severe galvanic corrosion of existing zinc alloys in corrosive environments by synergistically matching the processes of "equal channel corner extrusion + high-energy nitrogen ion implantation + surface biomimetic coating deposition". At the same time, the dense deposition layer helps to inhibit the rapid dissolution of zinc alloy surface and significantly reduces the corrosion rate of zinc alloy in corrosive environments.

[0022] (2) The preparation method provided by the present invention is convenient to operate, has strong parameter controllability, and is suitable for mass industrial production. The good deposition layer helps to inhibit the activation and dissolution of the zinc alloy surface, and provides an effective solution for the surface modification of medical biodegradable zinc alloy.

[0023] (3) This invention achieves dense coating deposition by precisely controlling key process parameters such as pH, conversion time, and reaction temperature, thus avoiding the deposition of Zn. 2+ Potential risks of localized excessive release.

[0024] (4) This invention uses Sr, Dy, and Cu elements to purify the alloy liquid, improve the uniformity of the microstructure, and avoid the occurrence of local galvanic corrosion. The addition of copper can improve fluidity and enhance the corrosion resistance of zinc alloys in corrosive media. However, excessive copper content will increase the tendency for hot cracking. Therefore, this invention controls the copper content at 0.01%~0.03%. Strontium is a powerful deoxidizer and desulfurizer. During the smelting of copper alloys, it can react with harmful impurities such as oxygen and sulfur in the melt, thereby improving the purity of the alloy. The addition of strontium can also effectively refine the grain structure of the alloy casting, making its performance more uniform in subsequent processing and avoiding hot brittleness. In addition, strontium can promote bone formation and inhibit bone resorption (osteoclast activity), which is crucial for maintaining bone density and bone strength. However, excessive addition can easily lead to increased alloy brittleness. This invention controls the strontium content at 0.05%~0.15%. Dysprosium has a strong affinity for impurities such as oxygen, sulfur, and hydrogen, which can increase the recrystallization temperature of the alloy and form stable dispersed particles. Furthermore, by purifying impurities and forming a dense surface oxide film, it can significantly improve the corrosion resistance of the alloy. More importantly, due to its low solubility and poor absorption by the gastrointestinal tract, its content must be strictly controlled. This invention controls its content to 0.01%~0.05%. The alloy prepared by this invention exhibits excellent corrosion resistance, and the surface profile after corrosion is relatively smooth (S... a With a thickness of only 1.03 μm, and especially with the high controllability of parameters during the preparation process, it provides an effective solution for the surface modification of medical zinc alloys. Attached Figure Description

[0025] Figure 1 The surface morphology of the medical zinc alloy obtained in Example 1 after immersion (A) and the three-dimensional corrosion profile after product removal (B) are shown.

[0026] Figure 2 The surface morphology of the medical zinc alloy obtained in Example 2 after immersion (A) and the three-dimensional corrosion profile after product removal (B) are shown.

[0027] Figure 3 The surface morphology of the medical zinc alloy obtained in Example 3 after immersion (A) and the three-dimensional corrosion profile after product removal (B) are shown. Detailed Implementation

[0028] This invention provides a method for preparing a medical zinc alloy surface with excellent corrosion resistance and its application, solving the problems of uneven corrosion and severe localized corrosion in existing medical zinc alloys.

[0029] The technical solution of the present invention is as follows: This invention provides a method for preparing a medical zinc alloy with excellent corrosion resistance, comprising the following steps: S1. According to the mass percentage of chemical composition, the oxide scale on the surface of high-purity Zn ingots, high-purity Cu ingots (≥99.99%) and intermediate alloys Zn-5%Sr (≥99.16%) and Zn-5%Dy (≥99.58%) is mechanically polished and then melted, refined and cast.

[0030] S2. The ingot described in S1 is subjected to equal channel angular extrusion deformation to obtain an extruded zinc alloy; S3. Perform a high-energy ion implantation process on the zinc alloy described in S2 to obtain a nitrogen ion implanted zinc alloy; S4. The alloy described in S3 is coated to obtain a medical zinc alloy with excellent corrosion resistance.

[0031] In this invention, the surface oxide scale is polished and then mixed in a certain proportion before being melted. The melting temperature is 480℃~520℃ and the melting time is 30 min~40 min. The refining agent used is zinc chloride, with a dosage of 0.3%~0.8%. The casting temperature is 440℃~480℃ and the mold preheating temperature is 180℃~200℃. After cooling, the product is demolded.

[0032] In this invention, a certain amount of molybdenum disulfide + graphite lubricant is sprayed before extrusion. The extrusion temperature is 250℃~310℃, the extrusion speed is 5 mm / s~15 mm / s, the number of extrusion passes is 2~6, the extrusion angle is 105°~120°, the extrusion path alternates and rotates 90° each time, and a hydrostatic pressure of 0~10 MPa is applied at the outlet end. After extrusion, air cooling or water mist cooling is used to prevent deformation or grain growth.

[0033] In this invention, the surface is machined to a thickness of 0.20 mm to 0.60 mm before extrusion, and simultaneously subjected to argon ion sputtering cleaning. The sputtering time is 6 min to 10 min, the implantation energy is 25 to 30 keV, and the nitrogen ion implantation dose is 1 × 10⁻⁶. 17 ~2×10 17 cm -2 The injection angle is 0~15°, the injection time is 1.5~3 h, the beam current density is 15~20 μA / cm², and the vacuum degree is 1×10⁻⁶. -3 Pa.

[0034] In this invention, the alloy surface needs to undergo a certain alkaline pretreatment in NaOH solution (the mass concentration of the alkaline solution is 5%~7%, the alkaline washing temperature is 40℃~60℃, the alkaline washing time is 2 min~4 min, the biomimetic deposition solution contains Ca(NO3)2·4H2O (0.025 mol) + NH4H2PO4 (0.015 mol), the Ca / P ratio is 1.60~1.67, the pH value is 7.4~7.8, the conversion temperature is 37℃±1℃, and the reaction time is 4~6 h).

[0035] In this invention, the zinc alloy is composed of the following raw materials by mass fraction: Dy 0.01%~0.05%, Sr 0.05%~0.15%, Cu 0.01%~0.03%, with the balance being Zn.

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1 A medical zinc alloy with excellent corrosion resistance comprises the following components by weight percentage: Dy: 0.01%, Sr: 0.07%, Cu: 0.01%, with the balance being Zn.

[0038] This embodiment also provides a method for preparing a medical zinc alloy surface coating with excellent corrosion resistance, including the following steps: S1. After the surface oxide scale is polished, it is mixed and added in proportion and melted. The melting temperature is 500℃ and the melting time is 30 min. The refining agent is zinc chloride, and the dosage is 0.8%. The casting temperature is 460℃, the mold preheating temperature is 180℃, and it is demolded after cooling.

[0039] S2. Before extrusion, a certain amount of molybdenum disulfide + graphite lubricant is sprayed. The extrusion temperature is 280℃, the extrusion speed is 10mm / s, the number of extrusion passes is 4, and the extrusion angle is 105°. The extrusion is carried out in multiple passes by rotating 90° around the long axis of the sample after each extrusion. A hydrostatic pressure of 2 MPa is applied to the outlet end. After extrusion, air cooling or water mist cooling is used.

[0040] S3. After extrusion, the surface is machined to 0.20 mm and simultaneously cleaned by argon ion sputtering for 10 min at an implantation energy of 30 keV and a nitrogen ion implantation dose of 2 × 10⁻⁶. 17 cm -2 The injection angle was 15°, the injection time was 1.5 h, the beam current density was 20 μA / cm², and the vacuum degree was 1×10⁻⁶. -3 Pa.

[0041] S4. The alloy surface was pretreated by alkaline washing in NaOH solution (solution mass concentration of 5%, temperature of 60℃, alkaline washing time of 4 min, biomimetic deposition solution containing Ca(NO3)2·4H2O (0.025 mol) + NH4H2PO4 (0.015 mol), Ca / P ratio of 1.67, pH value of 7.5, conversion temperature of 37℃±1℃, reaction time of 4 h).

[0042] Figure 1 The surface morphology of the medical zinc alloy with excellent corrosion resistance obtained in Example 1 after immersion for 21 days and the three-dimensional corrosion profile after product removal are shown. The results indicate that the surface roughness S after product removal is... a Only 1.03 μm, root mean square height S q =1.73μm, maximum indentation height S v =16.0μm, skewness S sk =0.692, the surface morphology after immersion is relatively smooth and flat, showing a good uniform corrosion and dissolution process.

[0043] Example 2 A medical zinc alloy with excellent corrosion resistance comprises the following components by weight percentage: Dy: 0.02%, Sr: 0.10%, Cu: 0.03%, with the balance being Zn.

[0044] This embodiment also provides a method for preparing a medical zinc alloy surface coating, including the following steps: S1. After the surface oxide scale is polished, it is mixed and added in proportion and melted. The melting temperature is 500℃ and the melting time is 35min. The refining agent is zinc chloride, and the dosage is 0.8%. The casting temperature is 460℃ and the mold preheating temperature is 200℃. After cooling, it is demolded.

[0045] S2. Before extrusion, a certain amount of molybdenum disulfide + graphite lubricant is sprayed. The extrusion temperature is 280℃, the extrusion speed is 10mm / s, the extrusion passes are 6, the extrusion angle is 110°, and multiple extrusions are performed by rotating 90° around the long axis of the sample after each extrusion. A hydrostatic pressure of 2 MPa is applied to the outlet end, and air cooling or water mist cooling is used after extrusion.

[0046] S3. After extrusion, the surface is machined to 0.30 mm and simultaneously cleaned by argon ion sputtering. The sputtering time is 8 min, the implantation energy is 30 keV, and the nitrogen ion implantation dose is 2×10⁻⁶. 17 cm -2 The injection angle was 15°, the injection time was 1.5 h, the beam current density was 20 μA / cm², and the vacuum degree was 1×10⁻⁶. -3 Pa.

[0047] S4. The alloy surface was pretreated by alkaline washing in NaOH solution (solution concentration 5%, temperature 60℃, alkaline washing time 4 min, biomimetic deposition solution containing Ca(NO3)2·4H2O (0.025 mol) + NH4H2PO4 (0.015 mol), Ca / P ratio 1.67, pH value 7.5, conversion temperature 37℃±1℃, reaction time 4 h).

[0048] Figure 2 The surface morphology of the medical zinc alloy with excellent corrosion resistance obtained in Example 2 after immersion for 21 days and the three-dimensional corrosion profile after product removal are shown. The results indicate that the surface roughness S after product removal is... a =1.17μm, root mean square height S q =1.80μm, maximum indentation height S v =21.2μm, skewness S sk =0.235, the surface morphology after corrosion is relatively flat and uniform, and it also shows a uniform corrosion and dissolution process.

[0049] Example 3 A medical zinc alloy with excellent corrosion resistance comprises the following components by weight percentage: Dy: 0.05%, Sr: 0.08%, Cu: 0.03%, with the balance being Zn.

[0050] This embodiment also provides a method for preparing a medical zinc alloy surface coating, including the following steps: S1. After the surface oxide scale is polished, it is mixed and added in proportion and melted. The melting temperature is 500℃ and the melting time is 40min. The refining agent is zinc chloride, and the dosage is 0.8%. The casting temperature is 470℃ and the mold preheating temperature is 190℃. After cooling, it is demolded.

[0051] S2. Before extrusion, a certain amount of molybdenum disulfide + graphite lubricant is sprayed. The extrusion temperature is 290℃, the extrusion speed is 10mm / s, the extrusion passes are 4, the extrusion angle is 120°, and multiple extrusions are performed by rotating 90° around the long axis of the sample after each extrusion. A hydrostatic pressure of 2 MPa is applied to the outlet end, and air cooling or water mist cooling is used after extrusion.

[0052] S3. After extrusion, the surface is machined to 0.20 mm and simultaneously cleaned by argon ion sputtering. The sputtering time is 6 min, the implantation energy is 30 keV, and the nitrogen ion implantation dose is 2×10⁻⁶. 17 cm -2 The injection angle was 15°, the injection time was 1.5 h, the beam current density was 20 μA / cm², and the vacuum degree was 1×10⁻⁶. -3 Pa.

[0053] S4. The alloy surface was pretreated by alkaline washing in NaOH solution (solution concentration 5%, temperature 60℃, washing time 4 min, biomimetic deposition solution containing Ca(NO3)2·4H2O (0.025 mol) + NH4H2PO4 (0.015 mol), Ca / P ratio 1.67, pH value 7.5, conversion temperature 37℃±1℃, reaction time 4 h).

[0054] Figure 3 The images show the surface morphology and three-dimensional corrosion profile of the medical zinc alloy with excellent corrosion resistance obtained in Example 3 after immersion for 21 days, and the three-dimensional corrosion profile after product removal. Measurements were performed using a Zeiss LSM800 laser confocal microscope based on an ICCS infinity apochromatic and contrast-enhanced optical system at a wavelength of 405 nm. Roughness parameters were automatically acquired using Olympus LEXT software.

[0055] The measurement results show that the surface roughness S after product removal is... a =1.23μm, root mean square height S q =1.81μm, maximum indentation height S v =15.5μm, skewness S sk =0.594, the surface morphology after corrosion is relatively flat and uniform, and it also shows a uniform corrosion and dissolution process.

[0056] Compared to Examples 2 and 3, the zinc alloy obtained in Example 1 exhibits a surface morphology with fewer defects and a smoother corrosion profile. Its overall surface corrosion profile is only 1.03 μm. By adjusting the process parameters of the equal channel corner extrusion process, the high-energy nitrogen ion implantation process, and the reasonable ratio of the composition, concentration, and conversion time of the conversion solution, a medical zinc alloy material with relatively excellent corrosion resistance was obtained, providing an effective solution for the surface modification of medical zinc alloys.

[0057] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a corrosion-resistant medical zinc alloy, characterized in that, Includes the following steps: Raw materials are weighed according to the chemical composition of zinc alloy, and after cleaning the surface of the raw materials, they are smelted, refined and cast to obtain ingots. The ingot is subjected to equal-channel angular extrusion deformation to obtain an extruded zinc alloy; The zinc alloy was subjected to high-energy ion implantation to obtain a nitrogen-ion-implanted zinc alloy; A coating is prepared on the surface of the nitrogen-ion-implanted zinc alloy to obtain the zinc alloy.

2. The preparation method according to claim 1, characterized in that, The raw materials include Zn ingots, Cu ingots, and Sr-containing master alloys and Dy-containing master alloys.

3. The preparation method according to claim 2, characterized in that, The zinc alloy is composed of the following raw materials by mass fraction: Dy 0.01%~0.05%, Sr 0.05%~0.15%, Cu 0.01%~0.03%, with the balance being Zn.

4. The preparation method according to claim 1, characterized in that, The melting temperature is 480℃~520℃, and the melting time is 30 min~40 min; The refining agent used in the refining process is zinc chloride, and the amount of the refining agent added is 0.3% to 0.8% based on the total weight of the zinc alloy system. The casting temperature is 440℃~480℃, and the mold preheating temperature is 180℃~200℃.

5. The preparation method according to claim 1, characterized in that, The extrusion angle of the equal channel corner extrusion deformation is 105°~120°, and multiple extrusions are performed using a path that rotates 90° around the long axis after each extrusion.

6. The preparation method according to claim 5, characterized in that, The extrusion temperature for the equal channel corner extrusion deformation is 250℃~310℃, the extrusion speed is 5 mm / s~15 mm / s, the number of extrusion passes is 2~6, and a hydrostatic pressure of 0~10 MPa is applied at the outlet end.

7. The preparation method according to claim 1, characterized in that, The high-energy nitrogen ion injection has an injection energy of 25-30 keV, a nitrogen ion injection dose of 1×10 17 ~2×10 17 cm -2 , a beam current density of 15-20 μA / cm², and an argon ion sputtering cleaning treatment for 6-10 min before nitrogen ion injection; the nitrogen ion injection angle is 0-15°, the injection time is 1.5-3 h, and the vacuum degree is 1×10 -3 Pa.

8. The preparation method according to claim 1, characterized in that, The coating preparation is carried out in the following... Nitrogen ions are implanted into the surface of zinc alloy to deposit a biomimetic coating. The biomimetic deposition solution used for the biomimetic coating deposition has a Ca / P ratio of 1.60~1.67, a pH value of 7.4~7.8, and a conversion temperature of 37℃±1℃.

9. A zinc alloy prepared by the method according to any one of claims 1 to 8.

10. The application of the zinc alloy of claim 9 in a medical implant device.

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