CN109602960B

CN109602960B - Preparation method of medical zinc alloy bar with superplasticity

Info

Publication number: CN109602960B
Application number: CN201811544472.8A
Authority: CN
Inventors: 张海军; 王鲁宁; 周超; 冯相蓺; 张军伟; 宋彩霞; 崔晓珊; 徐凯丽; 赵彦伟; 万国江; 尹玉霞; 鲁守涛; 段翠海; 侯文博; 刘光
Original assignee: Shandong Rientech Medical Technology Co ltd
Current assignee: Shandong Rientech Medical Technology Co ltd
Priority date: 2018-12-17
Filing date: 2018-12-17
Publication date: 2022-04-01
Anticipated expiration: 2038-12-17
Also published as: CN109602960A

Abstract

The invention provides a preparation method of a superplastic zinc alloy support material, which comprises the steps of obtaining alloy components aiming at different implantation positions through calculation of a material first principle, smelting alloy main elements including iron (Fe), copper (Cu) and the like in heating equipment to obtain an alloy melt, carrying out high-energy ultrasonic treatment on the alloy melt, cooling the alloy melt step by step in a mould to obtain a zinc alloy cast ingot, and sequentially carrying out extrusion, drawing and annealing to obtain a zinc alloy cylindrical bar with superplastic characteristics. The alloy properties and components required by different parts are calculated by a first principle, the alloy melt is treated by high-energy ultrasonic to achieve the aims of degassing, removing impurities and refining crystal grains, and the crystallization process is more balanced by gradually cooling the die. The vascular stent processed by the zinc alloy material has proper supporting force, good compliance, stable plastic deformation capability and excellent degradability, and can be applied to implantation of blood vessels, cavities and orthopedics.

Description

Preparation method of medical zinc alloy bar with superplasticity

Technical Field

The invention belongs to the field of medical instruments and biomedical materials. In particular to a degradable zinc alloy intravascular and luminal stent material with superplasticity, a bone plate and bone nail material and a preparation method thereof.

Background

Coronary atherosclerotic heart disease is one of the leading causes of human death, and there are currently over 200 million coronary heart disease patients worldwide each year who require Percutaneous Transluminal Coronary Angioplasty (PTCA), with 70% of PTCA procedures requiring stenting, but with restenosis rates up to 20-30% after 6 months, and with about 10% of patients requiring stenting again, with a tremendous economic and psychological burden on the patients.

One of the mechanisms causing restenosis is elastic recoil, the human coronary artery is a muscular artery, and elastic fibers are contained in an inner elastic layer and an outer elastic layer, if the rigidity of the stent is too high, and the compliance of the stent is too poor after the stent is expanded, the elastic fibers can generate recoil force to resist the expansion so as to generate elastic recoil; if the mechanical strength of the stent is too low, the loss of the stent inner cavity can occur, the stent cannot play a supporting role, and the restenosis in the blood vessel can also be caused, and the reasons belong to the inadaptability of the blood vessel to the stent. The other reason is that the traditional stents all belong to inert metal stents with strong supporting force and high corrosion resistance, such as stainless steel, cobalt-chromium alloy, platinum-chromium alloy and the like, and the long-term implantation of the stents can stimulate the exposure of tissue factors formed by thrombus and bring corresponding inflammatory reaction.

In order to solve the problems of long-term indwelling of the stent and poor compliance, researches on degradable stents at home and abroad have already been carried out by a plurality of corresponding technologies:

U.S. Pat. No. 4, 20160213501, 1 discloses a degradable magnesium alloy stent, which comprises a metal coating layer which degrades more slowly than magnesium, similar to iron, zinc and high molecular polymer, so as to adjust the degradation speed of the magnesium stent.

Chinese patent application publication No. CN103736152A discloses a zinc-based alloy containing Ce, Mg, Ca, and Cu, with an elongation of 25%. A plurality of metal elements are introduced into the material, and the mechanical property of zinc is improved, so that the bio-absorbable zinc alloy with corrosion resistance is finally formed.

The degradable zinc-copper alloy mentioned in international publication number WO2017/028646A1 has the Cu content of 1-10 wt%, has the advantages of being good in mechanical property, easy to process, good in corrosion resistance, good in biocompatibility and the like, can be used as a material for preparing various degradable medical implantation instruments, has very good mechanical property and biocompatibility, can be completely degraded within 6-18 months, and meets the requirements of the implantation instruments on comprehensive mechanical property and biosafety of the material.

Chinese patent CN105925848A discloses a biomedical degradable zinc alloy implant material and a preparation method thereof, and the material comprises the following components by mass percent: al: 1-5%, Mg: 0.01-3%, Ca: 0.05-3%, Zr: 0.05-0.2%, and the balance of Zn and inevitable impurities, wherein the elongation of the material is more than 45%. The zinc alloy can be used for degradable medical implants, in particular blood vessel stents and orthopedic implants.

Chinese patent CN106862298A discloses a preparation method of a medical biodegradable zinc alloy capillary wire, which comprises the steps of sequentially carrying out vacuum melting and homogenization heat treatment on medical biodegradable zinc alloy to obtain a zinc alloy ingot, then sequentially carrying out turning and extrusion on the zinc alloy ingot to obtain a zinc alloy thick rod, sequentially carrying out rotary swaging and annealing on the obtained zinc alloy thick rod to obtain a thin rod, coating a graphite lubricant on the surface of the obtained thin rod, and then carrying out cold-drawing wire drawing to obtain the medical biodegradable zinc alloy capillary wire, wherein the diameter of the capillary wire is less than 0.1 mm. The zinc alloy pipe has excellent comprehensive mechanical property, good surface quality, good corrosion resistance and degradation uniformity, and the degradation rate also meets the clinical use requirement.

The material disclosed in the above patent has the main advantage of improving the degradation performance of the stent, but the added elements can greatly influence the degradation products and plastic deformation capability of the zinc alloy, and can influence the preparation of capillary tubes to a certain extent, thereby influencing the performance of the material as a vascular stent. Research on Al-Mg superplastic thin-wall pipes published in the university newspaper of Zhongnan, 8.month, Liuli Ming et Al, 2007 indicates that the superplastic deformation performance is favorable for large-deformation metal processing and pipe processing, and the surface of a processed workpiece is flat. In order to ensure that the mechanical property of the material can adapt to blood vessels as far as possible on the premise of ensuring the degradability, the mechanical property of the material is calculated by a strict first principle, and the mechanical property index and the element addition type which are suitable as a stent material are obtained by combining an animal experiment and a mechanical experiment.

When the zinc alloy bracket material with different mechanical property requirements is accurately prepared, the high-energy ultrasonic treatment is carried out on the alloy melt in order to ensure the plastic deformation capability of the bracket material as much as possible. The high-energy ultrasound has the effects of degassing, deslagging, homogenizing components and refining tissues in the melt treatment process. After the cavity is formed, it is equivalent to a low-pressure zone, the gas dissolved in the liquid phase can overflow and be gathered in the cavity to form bubbles, and the bubbles are gathered, grown and floated, so that the goal of degassing can be reached. And the bubbles are favorable for bringing the impurity particles to the surface of the melt in the floating process, thereby achieving a certain deslagging effect. The homogenization effect of the high-energy ultrasound on the melt is based on the stirring effect of the acoustic flow effect, the high-energy ultrasound depends on the macroscopic acoustic flow effect, and the stirring effect of the high-energy ultrasound is incomparable with that of the traditional stirring means. It not only makes the solid phase material in the liquid distribute more evenly, but also the liquid level is more stable. The result of high-energy ultrasonic can ensure that the alloy with higher Cu content can keep excellent plastic deformation capability while ensuring the requirement of mechanical property.

After a series of processing and annealing, the developed zinc alloy is refined, the sliding coefficient of grain boundaries of grains is increased, and the superplasticity characteristic is shown. Therefore, the degradable superplastic zinc alloy material disclosed by the invention is suitable for different implantation parts, different environments, pathological processes and the like, the plasticity of the zinc alloy is improved, the Young modulus of the alloy is reduced, the stress shielding effect in the application process of the orthopedic implantation material and the cardiovascular implantation material is reduced, the compliance of the stent is improved in the application of a cardiac stent, the recovery of vascular lesions is facilitated, the degradable superplastic zinc alloy material is easy to process and form, and the degradable superplastic zinc alloy material has application significance compared with other zinc alloy materials.

The zinc alloy material prepared by the invention is not only used as a coronary stent material, but also can be used for peripheral blood vessels and other body cavities, such as: urethra, esophagus, etc., and can also be used as internal fixing systems such as bone plate and bone nail, such as maxillofacial bone, skull, phalanx, etc.

Disclosure of Invention

The invention aims to make the following improvements aiming at the defects of plastic deformation capability and mechanical property improvement of magnesium and zinc alloy in the prior art:

in a first aspect, the invention provides a zinc-based alloy, which has superplastic characteristics at room temperature, can process special-shaped workpieces in a simpler and more effective mode in the process of processing a stent, has small stress after being implanted into a blood vessel, and is beneficial to the recovery of the elasticity of the blood vessel.

In a second aspect, the zinc-based alloy implant material provided by the invention is degradable.

In a third aspect, the present invention provides a method of making a zinc-based alloy implant material as described above.

In a fourth aspect, the invention provides a version of the zinc-based alloy implant material in the preparation of a vascular stent.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the invention, iron is introduced as a component of the zinc-based alloy implant material, so that a microelectrode is formed between zinc and iron, the microelectrode sacrifices an anode to protect a cathode, the activity of iron is low, and zinc can be preferentially degraded, namely, the iron is protected from degrading the zinc, so that the degradation rate of a zinc component is adjusted;

(2) the introduction of iron can also obviously improve the mechanical property of the zinc-based alloy implant material, so that the implant material is easy to process and form, the strength, the plasticity and other properties meet the basic requirements of human implant materials such as vascular stents, orthopedic internal fixation systems and the like, and Fe is widely present in hemoglobin in human bodies, and the amount required by adults every day is about 1mg, and finally the Fe can be metabolized in the bodies;

(3) in the invention, the copper element is introduced as the component of the zinc-based alloy implant material because the degradation product Cu of the copper in the zinc-based alloy implant material²⁺Has certain antibacterial effect, and can prevent infection (BCI) centered on apparatus;

(4) degradation product of copper, Cu²⁺Can promote the secretion of endothelial nitric oxide synthase (eNOS), maintain the integrity of vascular endothelium and the function of endothelial cells; is beneficial to stimulating the secretion of VEGF (vascular endothelial growth factor) and promoting the proliferation and migration of vascular endothelial cells, thereby being capable of promoting the rapid re-endothelialization of an implanted part and the recovery and maintenance of the normal function of vascular endothelium and inducing angiogenesis;

(5) as shown in a schematic diagram of high-energy ultrasonic treatment of an alloy melt in fig. 5, the alloy melt is transferred into a temperature control mold 3, a high-energy ultrasonic probe 1 is inserted into an alloy melt 4, an ultrasonic power supply 2 is turned on, and ultrasonic treatment is performed, so that the purposes of removing impurities, degassing and refining grains can be achieved;

(6) superplasticity is generally considered to be the property of a material to exhibit an abnormally higher than normal deformation state at a certain strain rate and a certain temperature, and is particularly indicated by low rheological resistance and high rheological performance. The zinc alloy discovered in the invention has the characteristic of superplastic deformation at room temperature, and the elongation before failure can reach 190% when the zinc alloy is stretched at a low speed. In the zinc-copper alloy, the mass fraction of Cu is preferably 0-5%, the total elongation at break of the alloy after drawing is greatly improved in the experimental process, the alloy melt is subjected to a series of process improvements, and high-energy ultrasonic treatment, so that the final elongation at break reaches over 100%, and the elongation at break can be used as a stent material after being over 20%, therefore, the zinc alloy has high plastic deformation capacity, the biocompatibility of the zinc alloy and the softness of human blood vessels and the convenience in the production and processing processes are greatly improved, and the zinc alloy has great significance in the processing process research of zinc alloy materials.

Drawings

FIG. 1 is a schematic view showing a shape of a zinc-based alloy implant material of example 1 when applied to a coronary stent;

FIG. 2 is a stress-strain curve after Zn-0.2Fe-0.5Cu drawing;

FIG. 3 is a schematic diagram of the metallographic structure of as-cast Zn-0.2Fe-0.5 Cu;

FIG. 4 is a schematic metallographic structure of as-cast Zn-0.8 Cu;

FIG. 5 is a schematic view of a high energy ultrasonic treatment of an alloy melt.

Detailed Description

According to the zinc-based alloy implant material, 0-14 wt% of Fe, 0-13 wt% of Cu, 0-1% of Mg, 0-1 wt% of Mn and the balance of Zn are contained according to the mass percentage, and 0.01-2 wt% of Fe, 0.01-2 wt% of Cu and the balance of Zn are preferably selected from the degradable superplastic zinc-based alloy implant material; more preferably, from 0.00wt% to 1.00wt% Fe, from 0.00wt% to 1.00wt% Cu, and the balance Zn, with the total amount of impurities being < 0.01 wt%. Wherein, the purity of the zinc, the iron and the copper is more than 99.99 percent, and the total content of impurities is less than or equal to 0.01 percent; particularly, the mixing of Al as an impurity is avoided because Al and Fe form Fe-Al intermetallic compounds, which affect the subsequent processing (mainly polishing).

The method for preparing the degradable superplastic zinc-based alloy implant material comprises the following steps:

according to the mass percentage, Zn and Cu or Zn, Fe and Cu are mixed evenly and then placed in a high-purity graphite crucible in SF₆And CO₂Smelting in the mixed gas atmosphere, and obtaining the zinc-based alloy implant material through high-energy ultrasonic treatment, extrusion, drawing and annealing; finally, the required shape is formed through a series of processing for use.

The present invention will be described more specifically and further illustrated with reference to specific examples, which are by no means intended to limit the scope of the present invention.

The methods used in the following examples are conventional methods unless otherwise specified (example 1). The percentages are mass percentage amounts unless otherwise specified.

Example 1: zinc-iron-copper alloy

The zinc-based alloy material of the embodiment is zinc-iron-copper alloy, and the preparation process specifically comprises the following steps:

1) according to the mass percentage, 12wt% of Fe, 1.8wt% of Cu and the balance of Zn (the total content of impurities is less than 0.001 wt%) are put in a protective gas SF₆(1 vol.%) and CO₂And in the atmosphere, adding the mixture into a high-purity graphite crucible, mixing and smelting to obtain the zinc-based alloy.

2) After smelting, the obtained zinc-based alloy is extruded into a bar with the diameter of 100mm and the length of 50 cm.

3) The obtained bar is annealed for a plurality of times (the temperature is 200-500 ℃, 30 min), drilled and finally drawn to form a capillary tube with the diameter of 1.58mm and the wall thickness of 0.127mm, and is formed by femtosecond laser engraving (the engraving pattern is shown in figure 1) and is intended to be used for coronary vessel stents.

Effect verification:

the zinc-based alloy material prepared by the method has the yield strength of about 210MPa, the tensile strength of about 264MPa and the elongation of 22 percent. Can adapt to the processing and using processes of the support pressing and lying and the support spreading, and is a coronary vessel support material with ideal mechanical property. The prepared coronary vessel stent is expanded according to the nominal diameter and then compressed to 90 percent, the supporting force is 1.8N, and the clinical use requirement is met; the degradation rate measured according to ASTM _ G31-72 was 0.19 mm/a; detecting blood compatibility according to a GB16886 series method, wherein the hemolysis rate is 1 percent and is 5 percent lower than a standard specified value; the cytotoxicity reaction is grade I, no subcutaneous stimulation and sensitization rate of 0%.

Antibacterial performance tests are carried out according to appendix A of QB/T2591-2003, namely Experimental methods for antibacterial Plastic antibacterial performance and antibacterial Effect, the antibacterial rates of Staphylococcus aureus and Escherichia coli are respectively 92% and 94%, and the antibacterial rate is judged to be 'antibacterial' according to 5.1 in the standard, namely table 1.

The materials of the following examples can be processed into the vascular stent of the present embodiment, and the preparation process of the alloy material will be highlighted below.

Example 2: zinc-iron-copper alloy

The zinc-based alloy material of this example is a zinc-iron-copper alloy containing 0.2wt% iron, 0.5wt% copper, and the balance zinc, with a total impurity content of < 0.001 wt%. The preparation process comprises the following steps:

1) putting the raw materials into a smelting furnace according to the mass percentage for smelting, and carrying out smelting under the protection of inert gas to obtain a bar with the diameter of 100mm and the length of 500 mm;

2) cutting the bar into zinc alloy bars with the diameter of 8-10 mm;

3) drawing the bar in the step 2) to a thin cylindrical bar with the diameter of 3mm

Example 3: zinc-copper alloy

The zinc-based alloy material of this example is a zinc-copper alloy containing 0.80wt% copper, the balance being zinc, and the total impurity content being less than 0.001%. The preparation process is as follows (method one):

1) mixing and smelting copper and zinc in a high-purity graphite crucible according to mass percent, and smelting in SF₆And CO₂The mixed gas atmosphere is protected;

2) transferring the alloy melt into a die, placing a high-energy ultrasonic probe, and cooling and forming step by step to obtain a bar with the diameter of 100mm and the length of 500 mm;

3) heating and extruding the mixture into a zinc alloy bar with the diameter of 8-10 mm;

4) drawing the alloy thin rod in the step 2) to form a thin wire with the diameter of 3mm for each lower 50 wires;

5) the filaments were annealed at 250 ℃ for 10 min.

Example 4: zinc-iron-copper alloy

The zinc-based alloy material of this example is a zinc-iron-copper alloy containing 0.2wt% iron, 0.5wt% copper, and the balance zinc, with a total impurity content of < 0.001 wt%. The procedure was as in example 3.

Example 5: zinc-iron-copper alloy

The zinc-based alloy material of this example is a zinc-copper alloy containing 0.5wt% of iron, 0.5wt% of copper, and the balance of zinc, and the total content of impurities is less than 0.001%, and the preparation process is the same as that of example 4.

Example 6: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 0.20wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 4.

Example 7: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 0.40wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 4.

Example 8: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 0.60wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 4.

Example 9: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 0.70wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 4.

Example 10: zinc-copper alloy

The zinc-based alloy material of this example is a zinc-copper alloy containing 1.00wt% copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 4.

Example 11: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 2.00wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 4.

Example 12: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 3.00wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 4.

Example 13: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 4.00wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 4.

Example 14: zinc-copper alloy

The zinc-based alloy material of this example is a zinc-iron alloy containing 0.5wt% copper, the balance being zinc, with a total impurity content of < 0.001 wt%. The preparation process is as follows (method two):

2) transferring the alloy melt into a die, placing a high-energy ultrasonic probe, and cooling and forming step by step;

4) drawing the alloy thin rod in the step 2) to form a thin wire with the diameter of 3mm for each lower 20 wires;

5) the filaments were annealed at 250 ℃ for 30 min.

Example 15: zinc-copper alloy

The zinc-based alloy material of this example is a zinc-copper alloy containing 0.60wt% copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 14.

Example 16: zinc-copper alloy

The zinc-based alloy material of this example is a zinc-copper alloy containing 0.80wt% copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 14.

Example 17: zinc-copper alloy

The zinc-based alloy material of this example is a zinc-copper alloy containing 1.00wt% of copper, the balance being zinc, and the total content of impurities being less than 0.001%, and the preparation process is the same as that of example 14.

Example 18: zinc-copper alloy

The zinc-based alloy material of this example is a zinc-copper alloy containing 2.00wt% copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as example 14.

Example 19: zinc-copper alloy

The zinc-based alloy material of this example is a zinc-copper alloy containing 4.00wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 14.

Example 20: zinc-copper alloy

The zinc-based alloy material of the embodiment is zinc-copper alloy, which contains 0.60wt% of copper and the balance of zinc, the total content of impurities is less than 0.001%, and the preparation process is as follows (method three):

1) mixing and smelting the raw materials in a high-purity graphite crucible according to the mass percentage, and smelting the mixture in SF₆And CO₂The mixed gas atmosphere is protected;

4) drawing the alloy thin rods in the step 2) to form cylinders with the diameter of 6mm by using 20 wires below each pass; annealing the cylinder at 250 deg.C for 30 min;

5) drawing 50 filaments below each channel of the thin strips in the step 4) to form thin cylindrical bars with the diameter of 3 mm;

6) annealing the cylindrical bar from 5) at 250 ℃ for 30 min.

Example 21: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 0.80wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 20.

Example 22: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 1.00wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 20.

Example 23: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 2.00wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 20.

Example 24: zinc-copper alloy

The zinc-based alloy material of this example is zinc-copper alloy, which contains 4.00wt% of copper, the balance being zinc, and the total impurity content being less than 0.001%, and the preparation process is the same as that of example 20.

Comparative example 1 (zinc-iron-copper alloy with Fe higher than 14%): a zinc-based alloy material was prepared according to the preparation method of example 1 of the present invention, and contains 16wt% of iron, 1wt% of copper, and the balance of zinc.

Comparative example 2 (zinc-copper alloy with Fe less than 0.01%): a zinc-based alloy material was prepared according to the preparation method of example 1 of the present invention, and contained 1wt% of copper, 0.001% of iron, and the balance of zinc.

Comparative example 3 (zinc-iron-copper alloy with functional ingredients such as Cu higher than 13%): the zinc-based alloy material prepared according to the preparation method of the embodiment 1 of the invention contains 14wt% of copper, 1wt% of iron and the balance of zinc.

Comparative example 4 (zinc-iron-copper-strontium-calcium alloy with Fe higher than 14%): the zinc-based alloy material prepared according to the preparation method of the embodiment 1 of the invention contains 16wt% of iron, 1wt% of copper, 8wt% of strontium, 8wt% of calcium and the balance of zinc.

Comparative example 5 (prior art zinc-based alloy without Fe): a zinc-based alloy material, prepared according to the method of the published patent application CN103736152A, contains 0.1wt% Ce,0.5wt% Mg,0.1wt% Ca,1.5wt% Cu, and the balance Zn.

Comparative example 6 (zinc-iron alloy with Fe higher than 14%): a zinc-based alloy material was prepared according to the preparation method of example 1 of the present invention, and contains 17wt% of iron, and the balance of zinc.

Comparative example 7 (Fe-free zinc material): a zinc-based alloy material was prepared according to the preparation method of example 1 of the present invention, which contained only zinc, 1wt% copper, and no other elements.

TABLE 1 mechanical properties of the examples

The results in table 1 show that the zinc-based alloy material of the invention, whether the mechanical strength (yield strength, tensile strength) or the elastic property (elastic modulus) and the elongation property (elongation), can meet the requirements of the material for being implanted in the body as support and processability; in addition, the material can be used as a biodegradable metal for implantable medical devices, the degradation speed (corrosion speed) is ideal, the average degradation speed is about 0.3mm/a, the cytotoxicity of the materials in examples 1 to 22 is 2 grade according to the test of an ISO10993 method, and the materials have no obvious cytotoxicity, no subcutaneous irritation, no sensitization and genetic toxicity and can be used as in-vivo implantation materials.

In the process of material development, the super-plasticity characteristic is discovered, so that the processing technology is improved on the basis of the

embodiments

1, 2 and 3, the processing parameters are refined, and the zinc alloy has the super-plasticity characteristic by multi-pass extrusion and drawing. From the mechanical property data in table 1, it can be seen that the yield strength and tensile strength are improved and the young's modulus is increased to some extent as the Cu content is increased in any of the three processing methods. The elongation at break of the zinc alloy with 0.2% to 1% Cu content is the best, and 0.6% and 0.8% are preferred. The three processing methods are combined with performance requirements of different implantation positions calculated by theory, and processing methods of different embodiments are preferably selected for different implantation positions. The method I is preferably selected for the stent material used for coronary vessels, blood vessels in an oven and peripheral blood vessels, wherein the components of the stent material are 0.2-1.0% of Cu and the balance of zinc; for the stent material components of esophagus, trachea, bronchus, stomach and intestine, biliary tract, ureter, urethra and the like, 1-4% of Cu and the balance of Zn, the processing method is a second method; for processing internal fixing systems such as bone plate and bone nails, the material components are 2% -4% of Cu and the balance of Zn, and the processing method is the third method.

Compared with the zinc-based alloy implant material of the invention, the materials of comparative examples 1-6 have too low mechanical strength (like comparative example 2) to be used as implants with requirements on load-bearing performance; or the elongation at break is poor, the plasticity is not suitable for processing and forming the bracket microtube, and the superplastic zinc alloy of the invention well solves the problem of plastic forming.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a medical zinc alloy stent material with superplasticity is characterized by comprising the following steps:

1) feeding zinc, copper or zinc, copper and iron raw materials according to a certain proportion, and smelting in vacuum or inert atmosphere;

2) wherein the mass fraction of copper in the zinc-copper-iron alloy is 0.5wt%, the mass fraction of iron is not more than 0.2wt%, the content of iron is not zero, and the balance is zinc with the purity of more than 99%;

3) wherein the mass fraction of copper in the zinc-copper alloy is 0.6-0.8wt%, and the balance is zinc with the purity of more than 99%;

4) heating metal zinc to 650 +/-50 ℃ for melting, adding other metals with the calculated mass ratio into the molten zinc, transferring the molten alloy into a temperature control mold after the metals are completely melted, opening protective gas equipment, inserting a high-energy ultrasonic probe into the molten alloy for ultrasonic treatment, and cooling and forming step by step to obtain a bar ingot;

5) heating and extruding a bar material with the diameter of 8-10mm, drawing by the reducing amount of 20-50 wires per pass, and carrying out heat preservation and annealing at 250 ℃ for a period of time to obtain the bar material with the diameter of 3mm, which is refined in crystal grains and uniform in structure, and has the deformability which is abnormally higher than that of zinc casting;

6) the material is suitable for in vivo vascular implant materials, cavity implant materials and bone implant materials.

2. The preparation method of the medical zinc alloy stent material with superplasticity according to claim 1, wherein the smelting furnace is a resistance furnace or an induction furnace.

3. The preparation method of the medical zinc alloy stent material with superplasticity according to claim 1, wherein the protective gas is SF₆、CO₂Or other inert gas that does not react with the metal element.

4. The preparation method of the medical zinc alloy stent material with superplasticity according to claim 1, wherein the alloy casting mold has a temperature-controllable function, and the alloy melt is gradually cooled at 400 ℃, 350 ℃, 300 ℃ and 250 ℃.

5. The preparation method of the medical zinc alloy stent material with superplasticity according to claim 1, wherein 50 wires are preferably arranged at each passage during drawing, and finally a bar with the diameter of 3mm is obtained.

6. The preparation method of the medical zinc alloy stent material with superplasticity according to claim 1, wherein the annealing time is preferably 10-30 min.

7. The method for preparing medical zinc alloy stent material with superplasticity as claimed in claim 1, wherein the applicable scope includes dilation, fixation and repair of coronary vessels, intracranial vessels, peripheral vessels, esophagus, trachea, bronchus, stomach and intestine, biliary tract, ureter, urethra, human maxillofacial bone, skull and phalanx.

8. The preparation method of the medical zinc alloy stent material with superplasticity according to claim 1, wherein the drawing process comprises cold drawing and hot drawing.