Medical zinc alloy and application thereof

Abstract

This invention relates to the field of zinc alloy plastic processing technology, specifically to a medical zinc alloy and its applications. The medical zinc alloy of this invention is composed of the following chemical components by mass percentage: Ag 0.01%~0.02%, Mn 0.01%~0.02%, Cu 0.05%~0.30%, Zr 0.01%~0.03%, with the balance being Zn. This invention utilizes a synergistic deformation process involving isothermal multi-directional forging, medium-low temperature variable diameter extrusion, gradient cooling heat treatment, and surface mechanical grinding. The resulting medical zinc alloy possesses a fine-grained matrix structure and a gradient nanostructure on the surface. This not only enhances the alloy's resistance to plastic deformation under normal loads but also, through the synergistic effect of high-density dislocation structure and severe lattice distortion, increases the resistance to dislocation movement and reduces grain boundary slip, giving the medical zinc alloy comprehensive mechanical properties that combine high hardness and high toughness.

Description

Technical Field

[0001] This invention relates to the field of zinc alloy plastic processing technology, specifically to a medical zinc alloy and its applications. Background Technology

[0002] Compared to traditional medical implant materials, the new generation of medical zinc alloys exhibits several significant advantages. First, the standard electrode potential of zinc alloys falls between that of magnesium (-2.372V) and iron (-0.447V), theoretically providing a moderate degradation rate. This not only ensures the structural integrity of the implant during the fracture healing period (approximately 6 months) but also allows for gradual degradation after healing, avoiding the need for secondary surgery. Second, the low melting point of zinc alloys facilitates molding and processing, significantly reducing the difficulty and cost of medical material manufacturing. Most importantly, zinc alloys possess excellent physiological functions, such as participating in enzyme activity regulation and immune responses; their degradation products are harmless to the human body and can be normally metabolized and excreted. Furthermore, the mechanical strength of zinc alloys is comparable to that of human cortical bone, significantly reducing the stress shielding effect.

[0003] However, the room temperature mechanical strength of zinc alloys is insufficient to meet the long-term load-bearing performance requirements of bone repair materials. Furthermore, nonlinear load friction and wear inevitably occur between clinical implants and human bone / tissue, accompanied by the generation of numerous micro-scale debris. This can even induce a decrease in mitochondrial membrane potential (by as much as 35% ± 6.2%) and an increase in reactive oxygen species levels, severely hindering the bone tissue healing process. Especially with excessive Zn... 2+ Dissolution and debris can easily trigger pathological reactions such as local inflammation and even nerve damage, seriously threatening human life and health. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a medical zinc alloy and its applications. The medical zinc alloy of this invention is composed of Ag 0.01%~0.02%, Mn 0.01%~0.02%, Cu 0.05%~0.30%, Zr 0.01%~0.03%, with the balance being Zn. Through a synergistic deformation process system of "isothermal multi-directional forging + medium-low temperature variable diameter extrusion + gradient cooling heat treatment + surface mechanical grinding treatment", it obtains a microstructure with both high hardness and high toughness, greatly improving the wear performance of the medical zinc alloy.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first objective of this invention is to provide a medical zinc alloy, which is made of the following chemical components by mass percentage: Ag 0.01%~0.02%, Mn 0.01%~0.02%, Cu 0.05%~0.30%, Zr 0.01%~0.03%, with the balance being Zn, and the sum of the mass percentages of each chemical component is 100%. This mass percentage of chemical components is based on the principle of limiting solid solubility of each element in the Zn matrix, ensuring that Ag, Mn, Zr, and Cu exist in solid solution or micro / nano-scale dispersed phases, effectively suppressing the precipitation of coarse and hard intermetallic compounds. This improves the mechanical properties of the medical zinc alloy while avoiding the deterioration effects of harmful second phases on corrosion resistance and biocompatibility.

[0006] The preparation method of the medical zinc alloy includes the following steps: S1. Using Zn ingots, Ag chips, Zn-3%Mn master alloy, Zn-5%Zr master alloy and Zn-5%Cu master alloy as smelting metals, the smelting metals are smelted according to the mass percentage of each chemical component to form a molten alloy liquid, which is then cast and cooled to obtain an alloy ingot.

[0007] S2. The alloy ingot is subjected to isothermal multi-directional forging treatment. The isothermal multi-directional forging treatment refines the grains of the alloy ingot and compacts the pores of the alloy ingot, thereby improving its density and obtaining a relatively uniform forged zinc alloy.

[0008] S3. The forged zinc alloy is subjected to medium-low temperature variable diameter extrusion treatment to further refine the microstructure of the forged zinc alloy and improve its deformation resistance, thereby obtaining the extruded zinc alloy.

[0009] S4. The extruded zinc alloy is subjected to gradient cooling heat treatment to accelerate the formation of fine equiaxed crystals and obtain the heat-treated zinc alloy.

[0010] S5. The heat-treated zinc alloy is subjected to surface mechanical polishing (SMAT) to induce severe plastic deformation on the surface of the heat-treated alloy, driving the proliferation and entanglement of dislocations, which in turn triggers grain fragmentation and dynamic recrystallization, forming a nanocrystalline-submicron-fine-grained composite structure with a gradient distribution from the surface to the interior. This further improves the wear resistance and comprehensive mechanical properties of the heat-treated zinc alloy, resulting in a medical-grade zinc alloy. This composite microstructure not only significantly improves surface hardness and deformation resistance, but also endows the alloy with excellent wear resistance by reducing the coefficient of friction, inhibiting abrasive grain embedding and crack initiation.

[0011] Preferably, the isothermal multi-directional forging process is carried out under the following conditions: the initial forging temperature is 350℃~360℃, the final forging temperature is 310℃~320℃, and the forging strain rate is 0.1 / s~0.2 / s, and each side is forged 4 to 6 times.

[0012] Preferably, before the isothermal multidirectional forging process, the alloy ingot is subjected to a solution treatment. The solution treatment conditions are: holding at 350℃ for 6 hours. This temperature-time parameter is determined comprehensively based on the limiting solid solubility of each alloying element in the Zn matrix, the characteristics of the Zn-Ag / Cu / Mn / Zr binary phase diagram, and atomic diffusion kinetics. The aim is to achieve sufficient solid solution of microalloying elements, eliminate casting segregation, and provide a uniform single-phase solid solution structure for subsequent isothermal forging.

[0013] Preferably, a three-section horizontal continuous variable diameter die is used for medium and low temperature variable diameter extrusion at 320℃~380℃. The die orifice diameters are as follows: the first section diameter is 40mm, the second section diameter is 25mm, and the third section diameter is 8mm~10mm. The extrusion rates of the first and second sections are the same, both 5m / min~10m / min, and the extrusion rate of the third section is 10m / min~15m / min.

[0014] Preferably, the conditions for gradient cooling heat treatment are: a vacuum degree of less than 1×10⁻⁶. -2 In an environment of Pa, first heat-treat at 240℃~280℃ for 1h~2h, then heat-treat at 180℃~220℃ for 1h~3h.

[0015] Preferably, the surface mechanical grinding treatment conditions are as follows: using GCr15 steel as the grinding ball and alcohol as the medium filler, grinding for 30 min to 45 min at a vibration frequency of 60 Hz and a vibration amplitude of 3 mm to 6 mm; wherein, the filling rate of the grinding ball is 60% to 80%, and the volume percentage of alcohol is 0.05% to 0.5%.

[0016] Preferably, the smelting conditions are: first, evacuate to a vacuum of 3×10⁻⁶. -3 Argon gas is then introduced into Pa, and the mixture is melted at 650~750℃ for 10min~20min.

[0017] Preferably, the casting conditions are: casting at a casting rate of 10 mm / min to 30 mm / min at a temperature of 640°C to 660°C.

[0018] Preferably, the cooling rate is 0.5℃ / s to 2℃ / s. The cooling rate is designed to prevent the formation of hot cracks during the alloy solidification process and to obtain relatively fine as-cast grains.

[0019] A second objective of this invention is to provide the application of the above-mentioned medical zinc alloy in the preparation of medical zinc alloy rods or plates.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides a medical zinc alloy, which is made of the following chemical components in mass percentage: Ag 0.01%~0.02%, Mn 0.01%~0.02%, Cu 0.05%~0.30%, Zr 0.01%~0.03%, with the balance being Zn, and the sum of the mass percentages of each chemical component is 100%. The preparation method of medical zinc alloy is as follows: using Ag chips, Zn-3%Mn, Zn-5%Zr and Zn-5%Cu master alloys as smelting metals, the smelting metals are melted according to the mass percentage of each chemical component to form a molten alloy liquid. After casting and cooling, an alloy ingot is obtained. The alloy ingot is subjected to isothermal multi-directional forging to obtain a forged zinc alloy. The forged zinc alloy is subjected to medium and low temperature variable diameter extrusion to obtain an extruded zinc alloy. The extruded zinc alloy is subjected to gradient cooling heat treatment to obtain a heat-treated zinc alloy. The heat-treated zinc alloy is subjected to surface mechanical grinding to obtain a medical zinc alloy.

[0021] Compared to traditional single-deformation processes, this invention utilizes a synergistic deformation process system of "isothermal multi-directional forging + low-temperature variable-diameter extrusion + gradient cooling heat treatment + surface mechanical grinding," achieving a microstructure with both high hardness and high toughness, thus significantly enhancing the wear resistance of medical-grade zinc alloys. Specifically, isothermal multi-directional forging introduces high-density dislocation entanglement into the Zn matrix, laying the foundation for subsequent microstructure control; low-temperature variable-diameter extrusion achieves strain gradient accumulation, controllably introducing a residual compressive stress layer in the subsurface; gradient cooling heat treatment reduces the deformation resistance within the extruded zinc alloy, accelerating the formation of fine equiaxed grains; and surface mechanical grinding forms an ultrafine-grained microstructure with a gradient grain size distribution on the surface of the medical-grade zinc alloy. This gradient structure not only effectively resists abrasive grain embedding but also significantly reduces the risk of adhesive wear and fatigue wear by inhibiting crack initiation and propagation.

[0022] 2. Based on the principle of electronegativity of atomic standard electrodes, this invention involves the micro-composite addition of Zr, Cu, and Ag, which effectively increases the lattice distortion and the number of non-uniform nucleation sites in the molten alloy. Simultaneously, the oxidation tendency of Cu and Mn promotes the modification of the zinc oxide layer, reducing the susceptibility of localized corrosion on the surface of the medical zinc alloy.

[0023] 3. This invention significantly improves the density of the surface film of medical zinc alloy by regulating the Mn and Ag elements. At the same time, the micro-nano-scale second phase formed by the Mn and Ag elements with the Zn matrix can enhance the mechanical strength of the matrix as a hard phase. In addition, the zinc shavings generated during the wear process can repair wear defects under hydrolysis, effectively improving the friction performance of the alloy. Attached Figure Description

[0024] Figure 1 This is a microstructure diagram of the gradient fine-grained structure on the surface of the medical zinc alloy in Example 1.

[0025] Figure 2 The image shows the three-dimensional wear morphology of the medical zinc alloy in Example 1 under Hank's simulated body fluid environment.

[0026] Figure 3 This is a three-dimensional wear morphology image of the medical zinc alloy in Example 2 under Hank's simulated body fluid environment.

[0027] Figure 4 This is a three-dimensional wear morphology image of the medical zinc alloy of Example 3 under Hank's simulated body fluid environment. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the data in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] It should be noted that the technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased on the market or prepared by existing methods. Among them, high-purity Zn ingot refers to high-purity Zn ingot.

[0030] In existing technologies, it is often difficult to simultaneously achieve both mechanical properties and wear resistance in medical zinc alloys. On the one hand, traditional cast zinc alloys have coarse grains and loose structure, and their room temperature strength is insufficient to meet the long-term load-bearing requirements of bone repair materials (ASTM F382 standard specifies that the bending strength of bone plates must be >500MPa). On the other hand, although single deformation processes (such as conventional extrusion or rolling) can refine the grains, they are prone to forming texture and residual tensile stress inside the medical zinc alloy, leading to increased crack sensitivity and limited improvement in surface hardness. During friction and wear under physiological conditions, microscale debris is easily generated, inducing local inflammatory reactions and cytotoxicity.

[0031] To address the problems existing in the prior art, this invention provides a medical zinc alloy, made from the following chemical components by mass percentage: Ag 0.01%~0.02%, Mn 0.01%~0.02%, Cu 0.05%~0.30%, Zr The zinc alloy comprises 0.01%~0.03% zinc, with the balance being Zn, and the sum of the mass percentages of each chemical component is 100%. Its preparation method includes the following steps: using Zn ingots, Ag chips, Zn-3%Mn, Zn-5%Zr, and Zn-5%Cu master alloys as smelting metals, the smelting metals are melted according to the mass percentages of each chemical component to form a molten alloy liquid. After casting and cooling, an alloy ingot is obtained. The alloy ingot is subjected to isothermal multi-directional forging to obtain a forged zinc alloy. The forged zinc alloy is subjected to medium-low temperature variable diameter extrusion to obtain an extruded zinc alloy. The extruded zinc alloy is subjected to gradient cooling heat treatment to obtain a heat-treated zinc alloy. The heat-treated zinc alloy is subjected to surface mechanical grinding to obtain a medical-grade zinc alloy.

[0032] This invention utilizes a synergistic deformation process system of "isothermal multi-directional forging + medium-low temperature variable diameter extrusion + gradient cooling heat treatment + surface mechanical grinding treatment" to construct a high-density dislocation entanglement and residual compressive stress layer in the zinc matrix, and form a nanocrystalline-submicron-fine-grained composite structure with a gradient distribution of grain size on the surface. This results in comprehensive mechanical properties that combine high hardness, high toughness, and excellent wear resistance, effectively overcoming the technical bottlenecks of insufficient strength, easy surface wear, and limited biocompatibility of existing medical zinc alloys.

[0033] To enable those skilled in the art to more clearly understand the technical solution of the present invention, the following will provide a detailed description in conjunction with specific embodiments: Example 1 A method for preparing a medical-grade zinc alloy includes the following steps: S1. According to the mass percentage of each chemical component of the medical zinc alloy: Ag 0.02%, Mn 0.01%, Cu 0.10%, Zr 0.03%, Zn 99.84%, weigh out high-purity Zn ingots, Ag chips, Zn-3%Mn master alloy, Zn-5%Zr master alloy, and Zn-5%Cu master alloy; evacuate the melting furnace to 3×10 -3After Pa, argon gas is introduced, and an appropriate amount of high-purity Zn ingot is pre-melted at 620℃ for 15 minutes and then poured out to remove impurities in the furnace. Subsequently, after the furnace temperature is raised to 680℃, the weighed high-purity Zn ingot, Ag chips, Zn-3%Mn master alloy, Zn-5%Zr master alloy and Zn-5%Cu master alloy are placed together in the melting furnace and melted at 680℃ for 15 minutes. After melting, the temperature is lowered to 640℃, and a graphite cylindrical mold with an outer diameter of 150mm and an inner diameter of 110mm is used to cast the alloy at a casting rate of 10mm / min. After casting, the alloy ingot is cooled at a cooling rate of 0.5℃ / s to prevent cracking.

[0034] S2. The alloy ingot is first solution treated at 350℃ for 6 hours to obtain a solution-treated alloy ingot; then, under the conditions of initial forging temperature of 350℃, final forging temperature of 310℃ and forging strain rate of 0.1 / s, the solution-treated alloy ingot is subjected to isothermal multi-directional forging treatment, with each side forged 5 times to obtain a forged zinc alloy.

[0035] S3. A three-section horizontal continuous variable diameter die is used to perform medium-low temperature variable diameter extrusion treatment on forged zinc alloy at 350℃. After extrusion, water cooling treatment is performed immediately to obtain extruded zinc alloy. The die orifice diameters are as follows: the first section has a diameter of 40mm, the second section has a diameter of 25mm, and the third section has a diameter of 10mm. The extrusion rates of the first and second sections are the same, both at 8m / min, and the extrusion rate of the third section is 15m / min.

[0036] S4. When the vacuum degree is less than 1×10 -2 Under the condition of Pa, the extruded zinc alloy was subjected to gradient cooling heat treatment, first heat-treated at 260℃ for 1 hour, and then heat-treated at 220℃ for 1 hour to obtain the heat-treated zinc alloy.

[0037] S5. Using GCr15 steel grinding balls (hardness HRC 65+, total filler content 70%), the surface of the heat-treated zinc alloy was mechanically ground for 45 minutes at a vibration frequency of 60Hz and a vibration amplitude of 4mm to obtain medical-grade zinc alloy. The grinding balls were made of 2mm and 9mm particles graded in a 1:1 volume ratio, with alcohol as the filler medium, accounting for 0.5% of the volume.

[0038] According to GB / T12444-2006 "Metallic Materials Wear Test Methods", the medical zinc alloy was subjected to friction and wear tests using an MFT-4000 multifunctional surface performance tester. The load was 60N, the sliding distance was 8mm, the reciprocating linear speed was 240mm / s, the test time was 25min, the friction pair material was SiC (diameter 6mm), and the test was conducted in Hank's simulated body fluid environment. Figure 1The microstructure of the medical zinc alloy section prepared in Example 1 is shown. Figure 2 The three-dimensional friction and wear morphology of the medical zinc alloy prepared in Example 1 under simulated body fluid environment.

[0039] Figure 1 The results demonstrate that the surface nano-scale gradient fine-grained structure can significantly reduce the indentation depth of the medical zinc alloy surface and avoid local deformation defects and microcrack formation, thereby improving the material's resistance to friction and wear in simulated body fluid environments.

[0040] Example 2 A method for preparing a medical-grade zinc alloy includes the following steps: S1. According to the mass percentage of each chemical component of the medical zinc alloy: Ag 0.02%, Mn 0.01%, Cu 0.20%, Zr 0.03%, Zn 99.74%, weigh out high-purity Zn ingots, Ag chips, Zn-3%Mn master alloy, Zn-5%Zr master alloy, and Zn-5%Cu master alloy; evacuate the melting furnace to 3×10 -3 After Pa, argon gas is introduced, and an appropriate amount of high-purity Zn ingot is pre-melted at 620℃ for 15 minutes and then poured out to remove impurities in the furnace. Subsequently, after the furnace temperature is raised to 680℃, the weighed high-purity Zn ingot, Ag chips, Zn-3%Mn master alloy, Zn-5%Zr master alloy and Zn-5%Cu master alloy are placed together in the melting furnace and melted at 680℃ for 15 minutes. After melting, the temperature is lowered to 640℃, and a graphite cylindrical mold with an outer diameter of 150mm and an inner diameter of 110mm is used to cast the alloy at a casting rate of 10mm / min. After casting, the alloy ingot is cooled at a cooling rate of 1℃ / s to prevent cracking.

[0041] S2. The alloy ingot is first solution treated at 350℃ for 6 hours to obtain a solution-treated alloy ingot; then, under the conditions of initial forging temperature of 350℃, final forging temperature of 310℃ and forging strain rate of 0.1 / s, the solution-treated alloy ingot is subjected to isothermal multi-directional forging treatment, with each side forged 4 times to obtain a forged zinc alloy.

[0042] S3. A three-section horizontal continuous variable diameter die is used to perform medium-low temperature variable diameter extrusion treatment on forged zinc alloy at 350℃. After extrusion, water cooling treatment is performed immediately to obtain extruded zinc alloy. The die orifice diameters are as follows: the first section has a diameter of 40mm, the second section has a diameter of 25mm, and the third section has a diameter of 8mm. The extrusion rates of the first and second sections are the same, both at 8m / min, and the extrusion rate of the third section is 15m / min.

[0043] S4. When the vacuum degree is less than 1×10 -2Under the condition of Pa, the extruded zinc alloy was subjected to gradient cooling heat treatment, first heat-treated at 260℃ for 1 hour, and then heat-treated at 220℃ for 1 hour to obtain the heat-treated zinc alloy.

[0044] S5. Using GCr15 steel grinding balls (hardness HRC 65+, total filler content 70%), the surface of the heat-treated zinc alloy was mechanically ground for 45 minutes at a vibration frequency of 60Hz and a vibration amplitude of 3mm to obtain medical-grade zinc alloy. The grinding balls were made of 4mm and 9mm particles spaced in a 1:1 volume ratio, with alcohol as the filler medium, accounting for 0.5% of the volume.

[0045] Refer to GB / T12444-2006 "Metallic Materials - Test Methods for Wear". Figure 3 The three-dimensional friction and wear morphology of the medical zinc alloy prepared in Example 2 under simulated body fluid environment.

[0046] Example 3 A method for preparing a medical-grade zinc alloy includes the following steps: S1. According to the mass percentage of each chemical component of the medical zinc alloy: Ag 0.02%, Mn 0.01%, Cu 0.30%, Zr 0.03%, Zn 99.64%, weigh out high-purity Zn ingots, Ag chips, Zn-3%Mn master alloy, Zn-5%Zr master alloy, and Zn-5%Cu master alloy; evacuate the melting furnace to 3×10 -3 After Pa, argon gas is introduced, and an appropriate amount of high-purity Zn ingot is pre-melted at 620℃ for 15 minutes and then poured out to remove impurities in the furnace. Subsequently, after the furnace temperature is raised to 680℃, the weighed high-purity Zn ingot, Ag chips, Zn-3%Mn master alloy, Zn-5%Zr master alloy and Zn-5%Cu master alloy are placed together in the melting furnace and melted at 680℃ for 15 minutes. After melting, the temperature is lowered to 640℃, and a graphite cylindrical mold with an outer diameter of 150mm and an inner diameter of 110mm is used to cast the alloy at a casting rate of 10mm / min. After casting, the alloy ingot is cooled at a cooling rate of 0.5℃ / s to prevent cracking.

[0047] S2. The alloy ingot is first solution treated at 350℃ for 6 hours to obtain a solution-treated alloy ingot; then, under the conditions of initial forging temperature of 350℃, final forging temperature of 310℃ and forging strain rate of 0.1 / s, the solution-treated alloy ingot is subjected to isothermal multi-directional forging treatment, with each side forged 4 times to obtain a forged zinc alloy.

[0048] S3. A three-section horizontal continuous variable diameter die is used to perform medium-low temperature variable diameter extrusion treatment on forged zinc alloy at 350℃. After extrusion, water cooling treatment is performed immediately to obtain extruded zinc alloy. The die orifice diameters are as follows: the first section has a diameter of 40mm, the second section has a diameter of 25mm, and the third section has a diameter of 8mm. The extrusion rates of the first and second sections are the same, both at 6m / min, and the extrusion rate of the third section is 12m / min.

[0049] S4. When the vacuum degree is less than 1×10 -2 Under the condition of Pa, the extruded zinc alloy was subjected to gradient cooling heat treatment, first heat-treated at 260℃ for 1 hour, and then heat-treated at 220℃ for 1 hour to obtain the heat-treated zinc alloy.

[0050] S5. Using GCr15 steel grinding balls (hardness HRC 65+, total filler content 70%), the surface of the heat-treated zinc alloy was mechanically ground for 35 minutes at a vibration frequency of 60Hz and a vibration amplitude of 4mm to obtain medical-grade zinc alloy. The grinding balls were made of 7mm and 9mm particles graded in a 1:1 volume ratio, with alcohol as the filler medium, accounting for 0.5% of the volume.

[0051] Refer to GB / T12444-2006 "Metallic Materials - Test Methods for Wear". Figure 4 The three-dimensional friction and wear morphology of the medical zinc alloy prepared in Example 3 under simulated body fluid environment.

[0052] contrast Figure 2 , Figure 3 and Figure 4 The results showed that, compared to the three-dimensional wear profiles of the medical zinc alloys in Examples 2 and 3, the three-dimensional wear profile of the medical zinc alloy in Example 1 was flatter and had a lower wear rate. This is because the addition of mixed grinding balls ensured the depth of the surface nanolayer and optimized the surface roughness quality, while the surface refinement rate was higher, thereby reducing the wear behavior of debris particles on the substrate surface.

[0053] Example 4 A method for preparing a medical zinc alloy is the same as the method in Example 1, except that the isothermal multi-directional forging conditions in S2 are replaced with forging at an initial forging temperature of 360°C, a final forging temperature of 320°C, and a forging strain rate of 0.2 / s, and forging is performed 6 times on each side to obtain the medical zinc alloy.

[0054] Example 5 A method for preparing a medical zinc alloy is the same as that in Example 1, except that the conditions for low-temperature variable diameter extrusion in S3 are replaced with extrusion at 380°C, and the die apertures are as follows: the first section has a diameter of 40 mm, the second section has a diameter of 25 mm, and the third section has a diameter of 8 mm; the extrusion rates for the first and second sections are both 10 m / min, and the extrusion rate for the third section is 10 m / min, thus obtaining the medical zinc alloy.

[0055] Example 6 A method for preparing a medical zinc alloy is the same as that in Example 1, except that the gradient cooling heat treatment conditions in S4 are replaced with: a vacuum degree of less than 1×10⁻⁶. -2 In an environment of Pa, the zinc alloy is first heat-treated at 240℃ for 2 hours, and then heat-treated at 180℃ for 3 hours to obtain a medical-grade zinc alloy.

[0056] Example 7 A method for preparing a medical zinc alloy is the same as that in Example 1, except that the gradient cooling heat treatment conditions in S4 are replaced with: a vacuum degree of less than 1×10⁻⁶. -2 In an environment of Pa, the zinc alloy is first heat-treated at 280℃ for 1.5h, and then heat-treated at 200℃ for 2h to obtain a medical-grade zinc alloy.

[0057] Example 8 A method for preparing a medical zinc alloy is the same as the preparation method in Example 1, except that the surface mechanical grinding treatment conditions in S5 are replaced with: using GCr15 steel as the grinding ball and alcohol as the medium filler, grinding for 30 minutes at a vibration frequency of 60Hz and a vibration amplitude of 6mm; wherein the filling rate of the grinding ball is 80% and the volume percentage of alcohol is 0.05%, thus obtaining the medical zinc alloy.

[0058] Example 9 A method for preparing a medical zinc alloy is the same as the preparation method in Example 1, except that the surface mechanical grinding treatment conditions in S5 are replaced with: using GCr15 steel as the grinding ball and alcohol as the medium filler, grinding for 40 minutes at a vibration frequency of 60Hz and a vibration amplitude of 3mm; wherein the filling rate of the grinding ball is 60% and the volume ratio of alcohol is 0.5%, thus obtaining the medical zinc alloy.

[0059] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

Claims

1. A medical zinc alloy, characterized in that, The medical zinc alloy is made of the following chemical components by mass percentage: Ag 0.01%~0.02%, Mn 0.01%~0.02%, Cu 0.05%~0.30%, Zr 0.01%~0.03%, with the balance being Zn, and the sum of the mass percentages of each chemical component is 100%. The preparation method of the medical zinc alloy includes the following steps: Using Zn ingots, Ag chips, Zn-3%Mn master alloy, Zn-5%Zr master alloy and Zn-5%Cu master alloy as smelting metals, the smelting metals are smelted according to the mass percentage of each chemical component to form a molten alloy liquid, which is then cast and cooled to obtain an alloy ingot. The alloy ingot was subjected to isothermal multi-directional forging to obtain a forged zinc alloy. Forged zinc alloy is subjected to medium- and low-temperature variable diameter extrusion treatment to obtain extruded zinc alloy; The extruded zinc alloy was subjected to gradient cooling heat treatment to reduce the deformation resistance within the extruded zinc alloy and accelerate the formation of fine equiaxed crystals, thus obtaining a heat-treated zinc alloy. The surface of the heat-treated zinc alloy is mechanically ground to form a nano-gradient microstructure on the surface of the heat-treated zinc alloy, thus obtaining a medical zinc alloy.

2. The medical zinc alloy according to claim 1, characterized in that, The conditions for isothermal multidirectional forging are as follows: forging is carried out at an initial forging temperature of 350℃~360℃, a final forging temperature of 310℃~320℃, and a forging strain rate of 0.1 / s~0.2 / s, with each side forged 4 to 6 times.

3. The medical zinc alloy according to claim 1, characterized in that, Before isothermal multidirectional forging, the alloy ingot was also subjected to solution treatment, which was carried out at 350℃ for 6 hours.

4. The medical zinc alloy according to claim 1, characterized in that, A three-section horizontal continuous variable diameter die was used for medium and low temperature variable diameter extrusion at 320℃~380℃. The die orifice diameters were as follows: the first section diameter was 40mm, the second section diameter was 25mm, and the third section diameter was 8mm~10mm. The extrusion rates of the first and second sections were the same, 5m / min~10m / min, and the extrusion rate of the third section was 10m / min~15m / min.

5. The medical zinc alloy according to claim 1, characterized in that, The conditions for gradient cooling heat treatment are: a vacuum degree of less than 1×10⁻⁶. -2 In an environment of Pa, first heat-treat at 240℃~280℃ for 1h~2h, then heat-treat at 180℃~220℃ for 1h~3h.

6. The medical zinc alloy according to claim 1, characterized in that, The surface mechanical grinding conditions are as follows: using GCr15 steel as grinding balls, alcohol as the medium filler, and grinding for 30 min to 45 min at a vibration frequency of 60 Hz and a vibration amplitude of 3 mm to 6 mm. The grinding balls have a filling rate of 60% to 80%, and the alcohol has a volume percentage of 0.05% to 0.5%.

7. The medical zinc alloy according to claim 1, characterized in that, The smelting conditions are: first, evacuate to a vacuum of 3×10⁻⁶. - 3 Argon gas is then introduced into Pa, and the mixture is melted at 650~750℃ for 10min~20min.

8. The medical zinc alloy according to claim 1, characterized in that, The casting conditions are as follows: casting is carried out at a casting rate of 10 mm / min to 30 mm / min and at a temperature of 640℃ to 660℃.

9. The medical zinc alloy according to claim 1, characterized in that, The cooling rate is 0.5℃ / s to 2℃ / s.

10. The application of the medical zinc alloy of claim 1 in the preparation of medical zinc alloy rods or plates.

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