CN116920180B - Degradable metal material and preparation method and application thereof - Google Patents

Abstract

The invention provides a degradable metal material and a preparation method and application, which relate to the field of metals. In terms of mass percentage, the chemical composition of the degradable metal material includes: C: 0.05%~0.55%; Si: 0.07%~0.37% ; Mn: 0.50% ~ 1.80%; Cr ≤ 0.5%; Ni ≤ 0.5%; Cu ≤ 0.5%; the balance is Fe and inevitable impurities. The degradable metal is made by melting each raw material according to the ratio at 1100~1600℃ and molding it. It can be used in the production of vascular stents, intestinal implants, and orthopedic implants. By introducing the second phase of alloy elements, the present invention effectively controls the mechanical parameters of the degradable metal material. It can not only maintain the early mechanical properties of the degradable metal material, but also gradually degrade it in the later period, so as to meet the requirements of the degradable metal material within a predetermined period of time. controlled corrosion.

Description

A kind of degradable metal material and its preparation method and application

Technical field

The invention relates to the field of metal materials, and in particular to a degradable metal material and its preparation method and application.

Background technique

Implant intervention is one of the important means to treat vascular diseases, bone diseases and injuries. Vascular stents and bone fixation implants are key vascular implants and orthopedic implants, used to assist blood vessels and bone. repair and treatment, with high performance requirements and diverse functional requirements.

Currently, implants are mainly made of inert materials such as titanium and its alloys, stainless steel, etc. Although the above materials are relatively mature in clinical applications, due to their non-degradable and/or bioincompatible characteristics, After the treatment purpose is achieved, it will hinder and delay tissue healing in the body, cause rejection reactions, and also affect medical examination and treatment. This makes the permanent implant need to be re-installed after completing the temporary fixation and support functions. Surgical removal, therefore, research and development of degradable metal materials that can self-degrade after completion of service has become a new goal. The ideal degradable metal implant material should be able to provide better physiological repair, local vascular reconstruction, short-term longitudinal and radial straightening effects, the possibility of growth and later revascularization, and degradable metal implants The material should be detectable by MRI and IVUS during follow-up and not affect the revascularization procedure.

Magnesium alloys were first considered as degradable metal material scaffolds. Their main components are magnesium, aluminum or other alloying elements and a small amount of rare earth metals (Ce, Pr, Nd). Magnesium alloys can meet the requirements of biocompatibility, mechanical strength and degradation speed, and animal (pig) tests show that the inflammatory response is very small and there is no thrombosis, but obvious intimal cell proliferation is also observed. The more important problem with magnesium alloys is that they corrode too quickly in the human body, which limits their application. For example, clinical data released by Biotronik Company shows that bare magnesium alloy stents disappear in blood vessels in less than 2 months, causing blood vessels to collapse. Narrow again.

Recent reports indicate that iron stents are used for vascular stents and have good biocompatibility. As an essential micronutrient for the human body, iron participates in the transport of oxygen inside the body and the respiration of tissues. The production of iron alloys is much more difficult than that of magnesium alloys. There are problems such as low strength, poor plasticity and too fast absorption of magnesium alloys. For example, the medical stainless steel vascular stents disclosed in the prior art have excellent mechanical properties, but are also more corrosion-resistant, that is, they do not have the expected degradable properties and cannot meet the requirements of a controllable degradation rate of implant materials.

Contents of the invention

Therefore, the technical problem to be solved by the present invention is to overcome the shortcoming of the slow degradation rate of iron alloy stents in the prior art, thereby providing a degradable metal material with high mechanical strength and good degradation performance.

On the one hand, the present invention provides a degradable metal material. In terms of mass percentage, the chemical composition of the degradable metal material includes: C: 0.05%~0.55%; Si: 0.07%~0.37%; Mn: 0.50%~ 1.80%; Cr≤0.5%; Ni≤0.5%; Cu≤0.5%; P≤0.1%; S≤0.1%; the balance is Fe and inevitable impurities.

Optionally, the degradable metal material includes the following chemical components: C: 0.47%~0.55%; Si: 0.17%~0.37%; Mn: 0.50%~0.80%; Cr: 0.02%~0.25%; Ni: 0.02 %~0.25%; Cu: 0.02%~0.25%; P: 0.05%~0.035%; S: 0.05%~0.040%; the balance is Fe and inevitable impurities.

The organizational structure of the degradable metal material includes a two-phase alloy. The two-phase alloy includes a first phase and a second phase distributed on the surface of the first phase. The particle size in the second phase is 0.5 μm~ 7.0μm, the number of particles under the 2500X field of view of a metallographic microscope is 700 to 1500.

The particle size in the second phase is 1.5 μm~3.5 μm, and the number of particles under the 2500X field of view of a metallographic microscope is 200~400.

The organizational structure of the degradable metal material further includes a coating, and the coating is disposed on the surface of the second phase. The coating includes a degradable carrier and a drug in a mass ratio of 1~4:1~4.

The degradable carrier is polylactic acid, racemic polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxyalkanoate, polyacrylate, polyethylene succinate, polycarbonate, polyether ester middle.

The drug is at least one of rapamycin and paclitaxel.

On the other hand, the present invention also provides a preparation method of degradable metal materials. The preparation method of the degradable metal material includes the following steps: S1. Smelt each raw material according to the proportion at 1100~1600°C, and form.

It also includes step S2: rolling the steel ingot produced in step S1 into a plate, annealing it at 400°C to 700°C for 1 to 5 hours, and making the annealed plate into the required implant structure.

It also includes step S3: tempering the implant structure produced in step S2, the tempering temperature is above 150°C, and the tempering time is 0.5h~10h.

It also includes step S4: polishing the implant structure produced in step S2 or step S3.

The annealing temperature is 500~600°C. The tempering temperature is 550~650°C.

Electrolytic polishing is used in step S4, and the polishing liquid is composed of at least one of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, perchloric acid, hydrofluoric acid, citric acid, chromic acid, glacial acetic acid and ethylene glycol and pure water. Prepared by at least one mixture.

The polishing fluid temperature is 40~90℃, and the polishing time is 10s~10min.

It also includes step S5: coating the surface of the polished implant structure with a coating material.

In the step S4, the composition of the polishing liquid used includes: phosphoric acid, sulfuric acid and ethylene glycol with a mass ratio of 6~8:3~4:4~6; and/or, in step S5, spraying is used to coat all the polishing fluids. For the above-mentioned coating materials, the advancing speed of the spraying machine is 0.01mL/min~0.07mL/min.

The coating material includes a degradable carrier and a drug with a mass ratio of 1 to 4:1 to 4. The degradable carrier is polylactic acid, racemic polylactic acid, polyglycolic acid, polycaprolactone, and polyhydroxy chain. At least one of alkanoate, polyacrylate, polyethylene succinate, polycarbonate, and polyether ester, and the drug is at least one of rapamycin and paclitaxel.

The degradable metal material provided by the invention or the degradable metal material prepared by the preparation method can be used in the production of vascular stents, intestinal implants, and orthopedic implants.

Compared with the existing technology, the technical solution of the present invention has the following advantages:

1. A degradable metal material provided by the invention. In terms of mass percentage, the chemical composition of the degradable metal material includes: C: 0.05%~0.55%; Si: 0.07%~0.37%; Mn: 0.50%~ 1.80%; Cr≤0.5%; Ni≤0.5%; Cu≤0.5%; the balance is Fe and inevitable impurities. The present invention introduces alloying elements on the basis of the iron base material, and the content of the alloying elements is higher than its solubility in the iron base. It can effectively control the mechanical parameters of the degradable metal material and maintain the early mechanical properties of the degradable metal material. At the same time, it can gradually degrade in the later stage to meet the controllable degradation of degradable metals within a certain period of time.

2. A degradable metal material provided by the present invention. The organizational structure of the degradable metal material includes a two-phase alloy. The two-phase alloy includes a first phase and a second phase distributed on the surface of the first phase. The particle size in the second phase is 0.5 μm~7.0 μm, and the number of particles under the 2500X field of view of a metallographic microscope is 700~1500. The present invention introduces a second phase of alloy elements on the surface of the iron element scaffold structure, and effectively controls the mechanical parameters of the degradable metal material by limiting the particle size and quantity of the second phase distributed on the surface of the first phase, forming a two-phase alloy. The atomic arrangement on the phase interface no longer has lattice integrity. The phase interface will hinder the slippage of dislocations, thereby strengthening the material and increasing the overall strength and hardness of the material. The grains on the second phase formed are There are differences in the composition of the substrate, which can destroy the bond between grains under the action of phase interface stress and increase the corrosion rate of degradable metal materials.

3. The surface of the degradable metal material provided by the present invention can be provided with a coating. The coating includes a carrier and a contained drug. The present invention uses a degradable polymer carrier, which can not only realize the drug-loading function, but also improve the performance of the degradable metal material. It is biocompatible and promotes the degradation of degradable materials. The drug contained is rapamycin or paclitaxel, which has the ability to inhibit endothelial hyperproliferation and prevent restenosis. Among them, the higher the drug content, the higher the degree of endothelialization (vascular tissue coating the stent) in the body, the thicker the endothelium, and the degradation will be relatively slower; the larger the carrier amount, the faster the stent will degrade. The present invention limits the mass ratio of the carrier and the contained drug to further control the degradation of degradable metal materials. By controlling the thickness change ratio through the process, the amounts of drugs and carriers can be controlled, thereby collaboratively controlling the degradation rate of degradable metal materials in the body.

4. The present invention provides a method for preparing degradable metal materials, which includes smelting and shaping each raw material at 1100~1600°C according to the proportion. In the present invention, by smelting elements with specific components and specific contents, a degradable metal with a certain degradation rate and maintaining certain mechanical properties is formed. The formed iron-based alloy is first annealed so that crystal grains are generated on the surface of the first phase to form two phase alloy. The degradable metal formed after annealing will cause local plastic deformation or local relaxation inside the iron-based alloy to relax residual stress due to changes in the particle size, quantity and distribution of the second phase particles formed, eliminating part of the internal stress and reducing the overall hardness. , eliminating the possibility of partial stress corrosion, allowing the corrosion resistance to be restored to a certain extent; when tempering degradable metals after annealing, the particles are quickly cooled and refined after high-temperature tempering, and the grain structure morphology is restored and along the grain. Boundary distribution, by controlling the distribution of the second phase grain microstructure, the overall strength and plasticity of the material can be comprehensively optimized to control changes in mechanical properties and corrosion properties, and achieve a balance between the strength and corrosion rate of degradable metal materials while ensuring strength while also providing a good degradation rate.

5. In the preparation method of degradable metal materials provided by the present invention, the degradable metal materials are polished after tempering to further control the corrosion rate of the substrate. The present invention removes the material surface by polishing the prepared degradable metal materials. Defects such as pits, protrusions, inclusions, cracks, etc. reduce the activation energy of the material surface, reduce the surface area, further reduce corrosive sites, reduce the tendency of pitting corrosion, ensure the strength during service, and avoid problems due to pitting corrosion. Causes errors in corrosion rate.

6. The degradable metal prepared by the present invention can further control the degradation rate of the degradable metal by coating it on the surface of the implant structure and arranging degradable carriers and drugs to match the service time of the implant structure. , the propulsion speed of the carrier and the contained drug mixture sprayed on the degradable metal material is limited to control the uniformity of the coating on the degradable metal and ensure the uniformity of each position of the degradable metal during degradation, and finally spray The amount of carrier and drug can be controlled by the final wall thickness of the stent, and its uniformity can be determined by observation through light microscopy and other means.

Description of drawings

In order to more clearly explain the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings that need to be used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description The drawings illustrate some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is a microscopic observation view of the degradable metal stent after annealing in Embodiment 1 of the present invention under a 2500X field of view;

Figure 2 is a mechanical property curve measured on the degradable metal material plate after annealing in Example 1 of the present invention;

Figure 3 is a microscopic observation view of the degradable metal stent after tempering in Example 1 of the present invention under a 2500X field of view;

Figure 4 is the electrochemical polarity curve of the polished degradable metal stent prepared in Example 1 of the present invention;

Figure 5 shows the surface morphology of the metal matrix after corrosion products have been released from the degradable metal material prepared in Example 1 of the present invention after being soaked in vitro for 28 days;

Figure 6 is the surface morphology of the metal matrix after the drug-loaded degradable metal material prepared in Example 1 of the present invention was soaked in vitro for 28 days to produce corrosion products;

Figure 7 is the OCT scan result one month after the undrug-loaded degradable metal stent prepared in Example 1 of the present invention was implanted into the right coronary artery LCX of pigs;

Figure 8 is the OCT scan result one month after the drug-loaded metal stent prepared in Example 1 of the present invention was implanted into the right coronary artery RCA of pigs;

Figure 9 is a tissue section taken out after the drug-loaded metal stent prepared in Example 1 of the present invention was implanted into an animal.

Detailed ways

The following examples are provided to better understand the present invention. They are not limited to the best embodiments and do not limit the content and protection scope of the present invention. Anyone who is inspired by the present invention or uses the present invention to Any product that is identical or similar to the present invention by combining it with other features of the prior art falls within the protection scope of the present invention.

If no specific experimental steps or conditions are specified in the examples, the procedures can be carried out according to the conventional experimental steps or conditions described in literature in the field. If the manufacturer of the reagents or instruments used is not indicated, they are all conventional reagent products that can be purchased commercially.

The invention discloses a degradable metal material that enhances the overall strength by introducing a second phase. At the same time, the base material can be corroded controllably within a predetermined period of time, ensuring that the early mechanical properties can be maintained under prescribed scenarios. , and can be gradually degraded in the later stage. Biodegradable metal materials can be made into different shapes such as wires, sheets, blocks, and plates to meet the needs of different scenarios. Taking plates as an example, through mechanical mortise and tenon joints, welding and other processes, plates can be made into degradable metal brackets to meet treatment needs.

By introducing alloying elements C, Si, Mn, Cu, Ni, Cr, P and S into the material, a second phase particle dispersion phase is introduced on the metal surface. The alloying elements are dissolved in the matrix metal atoms. In this ratio, the content is so high that it exceeds its solubility, and a second phase appears, forming a two-phase alloy. The atomic arrangement at the interface between the two phases no longer has lattice integrity, and the phase interface will hinder the slip of dislocations, thereby strengthening the material and increasing the overall strength and hardness of the metal material. At the same time, compared with the base material without the introduction of alloying elements, the existence of the second phase increases its tendency of intergranular corrosion. Due to the composition difference between the second phase particles and the matrix, the existence of internal stress at the phase interface destroys the bonding between grains and increases the corrosion or degradation rate of the material to a certain extent. By adjusting the processing and treatment process of degradable metal materials and adjusting the shape, distribution and size of the second phase particles, a stable balance can be achieved between the overall strength of the material and the degradation rate, ensuring good degradation while ensuring strength. rate to meet demand.

After the metal components are smelted into molten steel, they are cast into steel ingots and shaped through different forming processes. Taking the rolling process as an example, under the external force of rolling, the grains on the surface of the material are extruded and elongated, resulting in deformation or even fragmentation, which further hinders the movement of dislocations and greatly improves the overall hardness and strength, but at the same time reduces The plasticity of the material is reduced, and residual stress is generated internally, which increases the phenomenon of stress corrosion and reduces the corrosion resistance of the material, making it difficult to process later or reducing the service life.

Based on this, the present invention performs annealing treatment on the rolled material, and the annealing temperature in this step is 500°C to 650°C. Within this temperature range, local plastic deformation or local relaxation process inside the material relaxes the residual stress, eliminates part of the internal stress, reduces the overall hardness, eliminates the possibility of partial stress corrosion, and restores corrosion resistance to a certain extent. Before tempering, there are second particles in the microstructure, but the size is large and no obvious grains are observed. At this time, the hardness and strength properties of the material are low. After the corresponding required structure is obtained (the structure can This structure is tempered for vascular stents, intestinal implants, orthopedic implants). After tempering, the grain boundaries are obvious, which can improve the overall strength. At the same time, the second phase particles are smaller and distributed along the grain boundaries, which hinders dislocation movement, further increasing the overall strength, but reducing the elongation, and the grain boundaries are obvious. The corrosion rate is increased to a certain extent, but the strength is improved to a greater extent. In the present invention, the tempering temperature is 400°C to 700°C. After tempering, the second phase particles of the microstructure are refined and distributed along the grain boundaries, so that the overall strength and plasticity of the material are comprehensively optimized. At the same time, by adjusting the temperature, duration and cooling method of tempering, the microstructure distribution of the material can be controlled and adjusted, thereby controlling the changes in mechanical properties and corrosion properties, so that the overall performance can meet the actual needs of various use scenarios. .

In order to further control the corrosion rate of the substrate, the present invention polishes the obtained structure, mainly through mechanical polishing, chemical polishing, and electrolytic polishing, aiming to remove surface defects such as pits, protrusions, inclusions, cracks, etc. By removing defects, the activation energy of the overall surface is reduced, the surface area is reduced, the corrodible sites are reduced, the tendency of pitting corrosion is reduced, and the strength during service is guaranteed to a certain extent. By adjusting the polishing time, the composition and temperature of the polishing fluid used in chemical and electrolytic polishing, the overall degradation and corrosion performance can be further controlled and adjusted. The polishing liquid can be prepared by mixing at least one of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, perchloric acid, hydrofluoric acid, citric acid, chromic acid, and glacial acetic acid with at least one of ethylene glycol and purified water. Taking the prepared metal stent as an example, the polishing effect can be controlled by the wall thickness of the prepared stent, and can be observed and judged using means such as a light microscope.

The degradable polymer coating has good biocompatibility, and the degradable polymer carrier can be polylactic acid, racemic polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxyalkanoate, polyacrylate , at least one of polyethylene succinate, polycarbonate, and polyether ester. It can load drugs and improve the overall biocompatibility, while promoting the degradation of metal structures. Taking the prepared metal stent as an example, the drug contained therein can be rapamycin or paclitaxel, which can inhibit excessive proliferation of endothelium and prevent restenosis to a certain extent. By adjusting the ratio of the two, the drug content and carrier amount on the final stent can be controlled, thereby controlling the degradation of the metal stent. At the same time, by adjusting the advancement speed of the sprayer when spraying the degradable polymer carrier and the contained drug mixture, the uniformity of the coating on the stent can be controlled, ensuring the uniformity of degradation at each location. The final amount of carrier and drug sprayed can be controlled by the final wall thickness of the stent, and its uniformity can be determined by observation using light microscopy and other means.

The testing methods for material mechanical properties, degradation and electrochemical properties, biocompatibility, etc. used in the following examples are as follows;

1. Mechanical properties—Testing methods for tensile strength and elongation:

According to Appendix B, Appendix C, and Appendix D in GB/T228.1-2010 "Metal Materials Tensile Test Part 1: Room Temperature Test Methods", make the annealed degradable metal plate sample into a suitable size. Taking the plate as an example, cut the annealed degradable metal plate into a tensile specimen with a width of 12.5mm, the original gauge length is 50mm, set the tensile speed to 5mm/min, and measure its tensile strength and elongation.

2. Test methods for degradation and electrochemical performance:

Taking a metal stent made of degradable metal as an example, the degradation performance test method is: ultrasonically clean the stent with purified water for 5 to 10 minutes with a cleaning power of 500W. After washing away impurities, use absolute ethanol for ultrasonic cleaning for 5 to 10 minutes. The cleaning power is 500W, and then the remaining ethanol on the surface is dried with an air gun for 3 to 5 minutes. After the preparation is completed, record the initial mass M ₀ of the cleaned scaffold, then completely immerse it in the prepared PBS solution, and culture it at 37±1°C. Take out the stent according to different set time points, ultrasonically clean it with 3wt% tartaric acid solution for 3 to 5 minutes to wash away the corrosion products on the stent surface, expose the metal matrix, record the mass M ₁ after cleaning with purified water and absolute ethanol, and calculate the stent mass Loss rate, the formula is as follows:

W=(M ₀ -M ₁ )/M ₀ ×100%;

W——stent mass loss rate;

M ₁ - the mass of the remaining metal stent matrix that has not been corroded or degraded;

M ₀ ——The initial mass of the metal stent matrix.

Regarding the electrochemical performance, a Princeton P4000 electrochemical workstation was used to measure the polarization curve of the degradable metal material in a PBS solution at 37°C. The test adopts a standard three-electrode system. The sample to be tested exposed in the solution is the working electrode, the saturated calomel electrode is the reference electrode, and the platinum electrode is the counter electrode. The test of the polarization curve is carried out at the open circuit potential. Place the working electrode in a PBS solution at 37°C and soak it until the open circuit potential is stable. Set the potential test range to select the relative open circuit potential ±600 mV, and set the potential scan rate to 0.1 mV/s. . The Keyence VHX7000 ultra-depth-of-field microscope was used to measure the exposed area of the working electrode, and the test results were analyzed using Origin software. The corrosion potential E _c and corrosion current density I _c of the degradable metal material in a 37°C PBS solution can be obtained.

3. Biocompatibility testing methods:

The biocompatibility of the application of degradable metal materials in the present invention is mainly determined by implanting the prepared structure into an animal for service and observing its endothelialization effect. After the structure corresponding to the needs is produced (the structure can be a vascular stent, intestinal implant, or orthopedic implant), it is sterilized to meet the sterility requirements and implanted into the corresponding use position in the animal's body. Taking metal stents made of degradable metal materials as an example, the sterilized stents are implanted into the left anterior descending artery LAD, left circumflex artery LCX or right coronary artery RCA of animals, and the stents are implanted at different set time points. The blood vessels were scanned using optical coherence tomography (OCT) to observe their endothelialization.

4. Test method for wall thickness:

Observe measurements under an ultra-depth-of-field microscope. The structure takes a metal bracket as an example. Select a measurement point at both ends and the middle of the bracket to measure the wall thickness of the bracket and record the average value. For stents with degradable polymer drug-loaded coatings, the measurement location selection method remains unchanged. The edges of the drug coating need to be clearly distinguished during measurement to avoid large errors. The number of measurement points can be increased if necessary.

Example 1

This embodiment provides a method for preparing degradable metal materials. The specific steps and parameters are as follows:

The composition of degradable metal materials is: C: 0.51%; Si: 0.27%; Mn: 0.60%; P: 0.022%; S: 0.030%; Cr: 0.20%; Ni: 0.23%; Cu: 0.19%; Impurities to avoid. The metal component is melted to form molten steel, and the steel ingot is prepared after the melting temperature is 1600°C. The plate is formed by rolling, then rolled into a steel strip, and annealed at the same time. The annealing temperature is 650°C and the annealing time is 2 hours. After annealing, observe the microstructure of the plate at 2500X, as shown in Figure 1. The size of the second phase particles on the surface is 0.5-3.2 μm, and the number of second-phase particles in the field of view is 900-1000. At the same time, no obvious grains are observed in this field of view, which may be due to the crushing of grains after rolling. The performance was tested by the above detection method, and the measured mechanical property curve is shown in Figure 2. After annealing, the tensile strength of the sheet of this composition is 1237MPa, and the elongation is 1.33%. After testing the performance by the above detection method, the measured corrosion potential of the plate with this composition after annealing was -0.67V, and the corrosion current was 9.33×10 ^-5 A·cm ^-2 . At the same time, it can be seen that compared with pure iron, the plate made in this embodiment has an increased corrosion rate and increases the possibility of being used as a degradable metal material.

In Example 1, plates are welded into metal brackets. A total of 5 metal brackets were made using the same materials and the same process, and were tempered and heat treated. The tempering heat treatment temperature is 700°C and the tempering time is 1 hour. The microstructure of the treated metal stent surface at 2500X is shown in Figure 3. Second phase particles can be observed on the surface, and their components are metal carbides. Compared with the annealed sheet, the distribution of second phase particles is more uniform and the size gap is smaller, and obvious grains can be observed. According to analysis, it is due to the rapid cooling of particles after high-temperature tempering and the recovery of the grain structure morphology, which shows that tempering can control the distribution, size and grain size of the second phase to a certain extent. The structure grain size is 1.5~2.2μm. The number of grains in this field of view is 300 to 400, and the restoration of grain boundaries is conducive to improving the overall mechanical strength.

The polishing slurry is configured according to the mass ratio of phosphoric acid, hydrochloric acid and ethylene glycol to 6:3:4. The metal stent after removing the surface oxide is electrolytically polished at a polishing slurry temperature of 68°C. The polishing time is 43 seconds. The stent is Wall thickness is 66μm. The mechanical properties of the polished degradable metal stent were tested. It was found that the tensile strength of the metal stent was 792MPa and the elongation rate was 5.69%. The performance was tested by the above detection method, and the measured electrochemical polarization curve is shown in Figure 4. The corrosion potential of the metal stent is -0.75V, and the corrosion current is 1.72×10 ^-4 A·cm ^-2 . Figure 5 shows the surface morphology of the metal matrix after the metal stent was soaked and degraded in vitro for 28 days to remove corrosion products. Corrosion products can be observed on part of the surface. The rest of the stent is the corroded metal matrix, but no obvious corrosion products are seen. Figure 6 The surface morphology of the metal matrix after the drug-loaded metal stent was soaked and degraded in vitro for 28 days to remove corrosion products. Compared with the bare stent without drug loading in Figure 5, it can be observed in Figure 6 that corrosion products are attached to almost all surfaces, proving the impact of the carrier on the degradation rate of the matrix.

In this embodiment, the polished metal stent is sprayed with drug. The degradable polymer carrier in the degradable polymer drug-loaded coating is polylactic acid, the drug is rapamycin, the mass ratio of the polymer carrier to the drug is 1:1, and the sprayer advancement speed is 0.030mL/min. The wall thickness of the drug stent after spraying is 73 μm. Figure 7 shows the OCT scan results one month after the drug-loaded metal stent was implanted into the pig's right coronary artery RCA, and Figure 8 shows the OCT scan results one month after the undrug-loaded bare metal stent was implanted into the pig's right coronary artery LCX. Comparing the two, it can be seen that the degradable polymer drug-loaded coating can promote endothelialization to a certain extent and improve biocompatibility. From Figure 9, it is observed that the tissue sections after degradation of the drug-loaded metal stent are well endothelialized at the degradation site, further indicating that the degradation products have excellent biocompatibility.

Example 2

This embodiment provides a method for preparing degradable metal materials. The specific steps and parameters are as follows:

The composition of degradable metal materials is: C: 0.51%; Si: 0.27%; Mn: 0.60%; P: 0.022%; S: 0.030%; Cr: 0.20%; Ni: 0.23%; Cu: 0.19%; Impurities to avoid. The metal component is melted to form molten steel, and the steel ingot is prepared after the melting temperature is 1600°C. The plate is formed by rolling, then rolled into a steel strip, and annealed at the same time. The annealing temperature is 650°C and the annealing time is 1.5 hours. After annealing, the microstructure of the plate was observed at 2500X. The size of the second phase particles on the surface was 0.9 to 3.8 μm. The number of second phase particles in the field of view was 700 to 900. At the same time, no second phase particles could be observed in the field of view. Obvious grains may be caused by grain breakage after rolling. After testing the performance through the above detection method, the measured mechanical properties are as follows: tensile strength is 1068MPa, and elongation is 2.01%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the plate of this composition after annealing is -0.52V, and the corrosion current is 6.75×10 ^-5 A·cm ^-2 .

In this embodiment, the plates are welded into a metal bracket. A total of 5 metal brackets were made using the same materials and the same process, and were tempered and heat treated. The tempering heat treatment temperature is 700°C and the tempering time is 1 hour. The microstructure of the treated metal stent surface at 2500X, and second phase particles can be observed on the surface. Compared with the annealed sheet, the distribution of second phase particles is more uniform and the size gap is smaller, and obvious grains can be observed. According to analysis, it is due to the rapid cooling of particles after high-temperature tempering and the recovery of the grain structure morphology, which shows that tempering can control the distribution, size and grain size of the second phase to a certain extent. The structure grain size is 1.7~2.9μm. The number of grains in this field of view is 250 to 360, and the restoration of grain boundaries is conducive to improving the overall mechanical strength.

Prepare the polishing slurry according to the mass ratio of phosphoric acid, hydrochloric acid and ethylene glycol at 8:3:6. Under the condition that the temperature of the polishing slurry is 67°C, electrolytic polish the metal stent after removing the surface oxide. The polishing time is 50 seconds. The wall thickness of the polished metal stent measured by the above detection method is 69 μm. The mechanical property curve of the metal stent measured by the above detection method is as follows: the tensile strength is 715MPa and the elongation is 6.87%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the metal stent is -0.69V and the corrosion current is 1.24×10 ^-4 A·cm ^-2 .

In this embodiment, the polished metal stent is sprayed with drug. The degradable polymer carrier in the degradable polymer drug-loaded coating is polylactic acid, the drug is rapamycin, the ratio of polymer carrier to drug is 1:1, and the sprayer advancement speed is 0.030mL/min. The wall thickness of the sprayed metal stent measured by the above detection method is 74 μm.

Example 3

This embodiment provides a method for preparing degradable metal materials. The specific steps and parameters are as follows:

The composition of degradable metal materials is: C: 0.51%; Si: 0.27%; Mn: 0.60%; P: 0.022%; S: 0.030%; Cr: 0.20%; Ni: 0.23%; Cu: 0.19%; Impurities to avoid. The metal component is melted to form molten steel, and the steel ingot is prepared after the melting temperature is 1600°C. The plate is formed by rolling, then rolled into a steel strip, and annealed at the same time. The annealing temperature is 650°C and the annealing time is 1 hour. After annealing, the microstructure of the plate was observed at 2500X. The size of the second phase particles on the surface was 1.4 to 5.3 μm. The number of second phase particles in the field of view was 600 to 850. At the same time, no second phase particles could be observed in the field of view. Obvious grains may be caused by grain breakage after rolling. After testing the performance through the above detection method, the measured mechanical properties are as follows: tensile strength is 994MPa, and elongation is 2.74%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the plate of this composition after annealing is -0.42V, and the corrosion current is 3.83×10 ^-5 A·cm ^-2 .

In this embodiment, the plates are welded into a metal bracket. A total of 5 metal brackets were made using the same materials and the same process, and were tempered and heat treated. The tempering heat treatment temperature is 700°C and the tempering time is 2 hours. The microstructure of the treated metal stent surface at 2500X, and second phase particles can be observed on the surface. Compared with the annealed sheet, the distribution of second phase particles is more uniform and the size gap is smaller, and obvious grains can be observed. According to analysis, it is due to the rapid cooling of particles after high-temperature tempering and the recovery of the grain structure morphology, which shows that tempering can control the distribution, size and grain size of the second phase to a certain extent. The structure grain size is 2.2~3.7μm. The number of grains in this field of view is 200 to 350, and the restoration of grain boundaries is conducive to improving the overall mechanical strength.

Prepare the polishing slurry according to the mass ratio of phosphoric acid, hydrochloric acid and ethylene glycol at 6:4:6. Under the condition that the temperature of the polishing slurry is 68°C, electrolytic polish the metal stent after removing the surface oxide. The polishing time is 40 seconds. The wall thickness of the polished metal stent measured by the above detection method is 68 μm. The mechanical property curve of the metal stent measured by the above detection method is as follows: the tensile strength is 667MPa and the elongation is 7.09%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the metal stent is -0.64V and the corrosion current is 9.97×10 ^-5 A·cm ^-2 .

In this embodiment, the polished metal stent is sprayed with drug. The degradable polymer carrier in the degradable polymer drug-loaded coating is polylactic acid, the contained drug is rapamycin, the ratio of polymer carrier to drug is 1:1, and the spraying machine advancement speed is 0.030mL/min. The wall thickness of the sprayed metal stent measured by the above detection method is 71 μm.

Example 4

This embodiment provides a method for preparing degradable metal materials. The specific steps and parameters are as follows:

The composition of degradable metal materials is C: 0.51%; Si: 0.27%; Mn: 0.60%; P: 0.022%; S: 0.030%; Cr: 0.20%; Ni: 0.23%; Cu: 0.19%; Fe and inevitable of impurities. The metal component is melted to form molten steel, and the steel ingot is prepared after the melting temperature is 1600°C. The plate is formed by rolling, then rolled into a steel strip, and annealed at the same time. The annealing temperature is 500°C and the annealing time is 2 hours. After annealing, the microstructure of the plate was observed at 2500X. The size of the second phase particles on the surface was 0.5 to 3.2 μm. The number of second phase particles in the field of view was 900 to 1000. At the same time, no second phase particles could be observed in the field of view. Obvious grains may be caused by grain breakage after rolling. After testing the performance with the above detection method, the measured mechanical properties are as follows: tensile strength is 1237MPa, and elongation is 1.33%. After testing the performance by the above detection method, the measured electrochemical polarization curve conversion data showed that the corrosion potential of the plate with this composition after annealing was -0.67V, and the corrosion current was 9.33×10 ^-5 A·cm ^-2 .

In this embodiment, the plates are welded into a metal bracket. A total of 5 metal brackets were made using the same materials and the same process, and were tempered and heat treated. The tempering heat treatment temperature is 600°C and the tempering temperature is 1 hour. The microstructure of the treated metal stent surface at 2500X, and second phase particles can be observed on the surface. Compared with the annealed sheet, the distribution of second phase particles is more uniform and the size gap is smaller, and obvious grains can be observed. According to analysis, it is due to the rapid cooling of particles after high-temperature tempering and the recovery of the grain structure morphology, which shows that tempering can control the distribution, size and grain size of the second phase to a certain extent. The structure grain size is 2.3~3.1μm. The number of grains in this field of view is 250 to 350, and the restoration of grain boundaries is conducive to improving the overall mechanical strength.

The polishing slurry is configured according to the mass ratio of phosphoric acid, hydrochloric acid and ethylene glycol to 6:3:4. When the polishing slurry temperature is 68°C, the metal stent is electrolytically polished after removing the surface oxide. The polishing time is 45 seconds. The wall thickness of the polished metal stent measured by the above detection method is 69 μm. The mechanical property curve of the metal stent measured by the above detection method is as follows: the tensile strength is 704MPa and the elongation is 6.11%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the metal stent is -0.84V and the corrosion current is 2.31×10 ^-4 A·cm ^-2 .

In this embodiment, the polished metal stent is sprayed with drug. The degradable polymer carrier in the degradable polymer drug-loaded coating is polylactic acid, the drug is rapamycin, the ratio of polymer carrier to drug is 1:1, and the sprayer advancement speed is 0.030mL/min. The wall thickness of the sprayed metal stent measured by the above detection method is 75 μm.

Example 5

This embodiment provides a method for preparing degradable metal materials. The specific steps and parameters are as follows:

The composition of degradable metal materials is: C: 0.51%; Si: 0.27%; Mn: 0.60%; P: 0.022%; S: 0.030%; Cr: 0.20%; Ni: 0.23%; Cu: 0.19%; Impurities to avoid. The metal component is melted to form molten steel, and the steel ingot is prepared after the melting temperature is 1600°C. The plate is formed by rolling, then rolled into a steel strip, and annealed at the same time. The annealing temperature is 500°C and the annealing time is 1.5 hours. After annealing, the microstructure of the plate was observed at 2500X. The size of the second phase particles on the surface was 0.5 to 3.2 μm. The number of second phase particles in the field of view was 900 to 1000. At the same time, no second phase particles could be observed in the field of view. Obvious grains may be caused by grain breakage after rolling. After testing the performance with the above detection method, the measured mechanical properties are as follows: tensile strength is 1237MPa, and elongation is 1.33%. After testing the performance by the above detection method, the measured electrochemical polarization curve conversion data showed that the corrosion potential of the plate with this composition after annealing was -0.67V, and the corrosion current was 9.33×10 ^-5 A·cm ^-2 .

In this embodiment, the plates are welded into a metal bracket. A total of 5 metal brackets were made using the same materials and the same process, and were tempered and heat treated. The tempering heat treatment temperature is 600°C, and the tempering temperature is 1 hour. The microstructure of the treated metal stent surface at 2500X, and second phase particles can be observed on the surface. Compared with the annealed sheet, the distribution of second phase particles is more uniform and the size gap is smaller, and obvious grains can be observed. According to analysis, it is due to the rapid cooling of particles after high-temperature tempering and the recovery of the grain structure morphology, which shows that tempering can control the distribution, size and grain size of the second phase to a certain extent. The structure grain size is 2.5~3.5μm. The number of grains in this field of view is 200 to 350, and the restoration of grain boundaries is conducive to improving the overall mechanical strength.

The polishing slurry is configured according to the mass ratio of phosphoric acid, hydrochloric acid and ethylene glycol to 8:3:4. The metal stent after removing the surface oxide is electrolytically polished at a polishing slurry temperature of 68°C. The polishing time is 40 seconds. The wall thickness of the polished metal stent measured by the above detection method is 64 μm. The mechanical property curve of the metal stent measured by the above detection method is as follows: the tensile strength is 673MPa and the elongation is 6.83%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the metal stent is -0.89V and the corrosion current is 2.85×10 ^-4 A·cm ^-2 .

In this embodiment, the polished metal stent is sprayed with drug. The degradable polymer carrier in the degradable polymer drug-loaded coating is polylactic acid, the drug is rapamycin, the ratio of polymer carrier to drug is 1:1, and the sprayer advancement speed is 0.030mL/min. The wall thickness of the sprayed metal stent measured by the above detection method is 77 μm.

Example 6

This embodiment provides a method for preparing degradable metal materials. The specific steps and parameters are as follows:

The composition of degradable metal materials is: C: 0.51%; Si: 0.27%; Mn: 0.60%; P: 0.022%; S: 0.030%; Cr: 0.20%; Ni: 0.23%; Cu: 0.19%; Impurities to avoid. The metal component is melted to form molten steel, and the steel ingot is prepared after the melting temperature is 1600°C. The plate is formed by rolling, then rolled into a steel strip, and annealed at the same time. The annealing temperature is 500°C and the annealing time is 1 hour. After annealing, the microstructure of the plate was observed at 2500X. The size of the second phase particles on the surface was 0.5 to 3.2 μm. The number of second phase particles in the field of view was 900 to 1000. At the same time, no second phase particles could be observed in the field of view. Obvious grains may be caused by grain breakage after rolling. After testing the performance with the above detection method, the measured mechanical properties are as follows: tensile strength is 1237MPa, and elongation is 1.33%. After testing the performance by the above detection method, the measured electrochemical polarization curve conversion data showed that the corrosion potential of the plate with this composition after annealing was -0.67V, and the corrosion current was 9.33×10 ^-5 A·cm ^-2 .

In this embodiment, the plates are welded into a metal bracket. A total of 5 metal brackets were made using the same materials and the same process, and were tempered and heat treated. The tempering heat treatment temperature is 600°C, and the tempering time is 2 hours. The microstructure of the treated metal stent surface at 2500X, and second phase particles can be observed on the surface. Compared with the annealed sheet, the distribution of second phase particles is more uniform and the size gap is smaller, and obvious grains can be observed. According to analysis, it is due to the rapid cooling of particles after high-temperature tempering and the recovery of the grain structure morphology, which shows that tempering can control the distribution, size and grain size of the second phase to a certain extent. The structure grain size is 1.5~2.2μm. The number of grains in this field of view is 300 to 400, and the restoration of grain boundaries is conducive to improving the overall mechanical strength.

The polishing slurry is configured according to the mass ratio of phosphoric acid, hydrochloric acid and ethylene glycol to 6:3:4. When the polishing slurry temperature is 60°C, the metal stent after removing the surface oxide is electropolished for 54 seconds. The wall thickness of the polished metal stent measured by the above detection method is 61 μm. The mechanical property curve of the metal stent measured by the above detection method is as follows: the tensile strength is 786MPa and the elongation is 5.57%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the metal stent is -0.81V and the corrosion current is 1.99×10 ^-4 A·cm ^-2 .

In this embodiment, the polished metal stent is sprayed with drug. The degradable polymer carrier in the degradable polymer drug-loaded coating is polylactic acid, the drug is rapamycin, the ratio of polymer carrier to drug is 1:1, and the sprayer advancement speed is 0.030mL/min. The wall thickness of the sprayed metal stent measured by the above detection method is 68 μm.

Example 7

This embodiment provides a method for preparing degradable metal materials. The specific steps and parameters are as follows:

The composition of degradable metal materials is: C: 0.51%; Si: 0.27%; Mn: 0.60%; P: 0.022%; S: 0.030%; Cr: 0.20%; Ni: 0.23%; Cu: 0.19%; Impurities to avoid. The metal component is melted to form molten steel, and the steel ingot is prepared after the melting temperature is 1600°C. The plate is formed by rolling, then rolled into a steel strip, and annealed at the same time. The annealing temperature is 550°C and the annealing time is 2 hours. After annealing, the microstructure of the plate was observed at 2500X. The size of the second phase particles on the surface was 0.5 to 3.2 μm. The number of second phase particles in the field of view was 900 to 1000. At the same time, no second phase particles could be observed in the field of view. Obvious grains may be caused by grain breakage after rolling. After testing the performance with the above detection method, the measured mechanical properties are as follows: tensile strength is 1237MPa, and elongation is 1.33%. After testing the performance by the above detection method, the measured electrochemical polarization curve conversion data showed that the corrosion potential of the plate with this composition after annealing was -0.67V, and the corrosion current was 9.33×10 ^-5 A·cm ^-2 .

In this embodiment, the plates are welded into a metal bracket. A total of 5 metal brackets were made using the same materials and the same process, and were tempered and heat treated. The tempering heat treatment temperature is 500°C, and the tempering time is 1 hour. The microstructure of the treated metal stent surface at 2500X, and second phase particles can be observed on the surface. Compared with the annealed sheet, the distribution of second phase particles is more uniform and the size gap is smaller, and obvious grains can be observed. According to analysis, it is due to the rapid cooling of particles after high-temperature tempering and the recovery of the grain structure morphology, which shows that tempering can control the distribution, size and grain size of the second phase to a certain extent. The structure grain size is 1.5~2.2μm. The number of grains in this field of view is 300 to 400, and the restoration of grain boundaries is conducive to improving the overall mechanical strength.

The polishing slurry is configured according to the mass ratio of phosphoric acid, hydrochloric acid and ethylene glycol to 8:3:4. When the polishing slurry temperature is 60°C, the metal stent after removing the surface oxide is electropolished for 120 seconds. The wall thickness of the polished metal stent measured by the above detection method is 53 μm. The mechanical property curve of the metal stent measured by the above detection method is as follows: the tensile strength is 739MPa and the elongation is 5.86%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the metal stent is -0.94V and the corrosion current is 2.51×10 ^-4 A·cm ^-2 .

In this embodiment, the polished metal stent is sprayed with drug. The degradable polymer carrier in the degradable polymer drug-loaded coating is polylactic acid, the drug is rapamycin, the ratio of polymer carrier to drug is 1:1, and the sprayer advancement speed is 0.030mL/min. The wall thickness of the sprayed metal stent measured by the above detection method is 59 μm.

Experimental example 8

This embodiment provides a method for preparing degradable metal materials. The specific steps and parameters are as follows:

The composition of degradable metal materials is: C: 0.51%; Si: 0.27%; Mn: 0.60%; P: 0.022%; S: 0.030%; Cr: 0.20%; Ni: 0.23%; Cu: 0.19%; Impurities to avoid. The metal component is melted to form molten steel, and the steel ingot is prepared after the melting temperature is 1100°C. The plate is formed by rolling, then rolled into a steel strip, and annealed at the same time. The annealing temperature is 400°C and the annealing time is 5 hours. After annealing, the microstructure of the plate was observed at 2500X. The size of the second phase particles on the surface was 0.5 to 3.2 μm. The number of second phase particles in the field of view was 900 to 1000. At the same time, no second phase particles could be observed in the field of view. Obvious grains may be caused by grain breakage after rolling. After testing the performance with the above detection method, the measured mechanical properties are as follows: tensile strength is 1237MPa, and elongation is 1.33%. After testing the performance by the above detection method, the measured electrochemical polarization curve conversion data showed that the corrosion potential of the plate with this composition after annealing was -0.67V, and the corrosion current was 9.33×10 ^-5 A·cm ^-2 .

In this embodiment, the plates are welded into a metal bracket. A total of 5 metal brackets were made using the same materials and the same process, and were tempered and heat treated. The tempering heat treatment temperature is 250°C, and the tempering time is 6 hours. The microstructure of the treated metal stent surface at 2500X, and second phase particles can be observed on the surface. Compared with the annealed sheet, the distribution of second phase particles is more uniform and the size gap is smaller, and obvious grains can be observed. According to analysis, it is due to the rapid cooling of particles after high-temperature tempering and the recovery of the grain structure morphology, which shows that tempering can control the distribution, size and grain size of the second phase to a certain extent. The structure grain size is 1.5~2.2μm. The number of grains in this field of view is 300 to 400, and the restoration of grain boundaries is conducive to improving the overall mechanical strength.

The polishing slurry is configured according to the mass ratio of phosphoric acid, hydrochloric acid and ethylene glycol to 8:4:4. When the temperature of the polishing slurry is 40°C, the metal stent after removing the surface oxide is electropolished for 5 minutes. The wall thickness of the polished metal stent measured by the above detection method is 68 μm. The mechanical property curve of the metal stent measured by the above detection method is as follows: the tensile strength is 786MPa and the elongation is 5.57%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the metal stent is -0.81V and the corrosion current is 1.99×10 ^-4 A·cm ^-2 .

In this embodiment, the polished metal stent is sprayed with drug. The degradable polymer carrier in the degradable polymer drug-loaded coating is polylactic acid, the drug is rapamycin, the ratio of polymer carrier to drug is 2:1, and the sprayer advancement speed is 0.070mL/min. The wall thickness of the sprayed metal stent measured by the above detection method is 74 μm. In addition, the in vitro degradation test observed the accelerated generation of stent corrosion products, which had coated the entire substrate surface around 21 days.

Example 9

This embodiment provides a method for preparing degradable metal materials. The specific steps and parameters are as follows:

The composition of degradable metal materials is: C: 0.51%; Si: 0.27%; Mn: 0.60%; P: 0.022%; S: 0.030%; Cr: 0.20%; Ni: 0.23%; Cu: 0.19%; Impurities to avoid. The metal component is melted to form molten steel, and the steel ingot is prepared after the melting temperature is 1400°C. The plate is formed by rolling, then rolled into a steel strip, and annealed at the same time. The annealing temperature is 700°C and the annealing time is 3 hours. After annealing, the microstructure of the plate was observed at 2500X. The size of the second phase particles on the surface was 0.5 to 3.2 μm. The number of second phase particles in the field of view was 900 to 1000. At the same time, no second phase particles could be observed in the field of view. Obvious grains may be caused by grain breakage after rolling. After testing the performance with the above detection method, the measured mechanical properties are as follows: tensile strength is 1237MPa, and elongation is 1.33%. After testing the performance by the above detection method, the measured electrochemical polarization curve conversion data showed that the corrosion potential of the plate with this composition after annealing was -0.67V, and the corrosion current was 9.33×10 ^-5 A·cm ^-2 .

In this embodiment, the plates are welded into a metal bracket. A total of 5 metal brackets were made using the same materials and the same process, and were tempered and heat treated. The tempering heat treatment temperature is 150°C and the tempering time is 10h. The microstructure of the treated metal stent surface at 2500X, and second phase particles can be observed on the surface. Compared with the annealed sheet, the distribution of second phase particles is more uniform and the size gap is smaller, and obvious grains can be observed. According to analysis, it is due to the rapid cooling of particles after high-temperature tempering and the recovery of the grain structure morphology, which shows that tempering can control the distribution, size and grain size of the second phase to a certain extent. The structure grain size is 1.5~2.2μm. The number of grains in this field of view is 300 to 400, and the restoration of grain boundaries is conducive to improving the overall mechanical strength.

The polishing slurry is configured according to the mass ratio of phosphoric acid, hydrochloric acid and ethylene glycol to 6:4:6. When the temperature of the polishing slurry is 90°C, the metal stent after removing the surface oxide is electropolished for 10 minutes. The wall thickness of the polished metal stent measured by the above detection method is 72 μm. The mechanical property curve of the metal stent measured by the above detection method is as follows: the tensile strength is 786MPa and the elongation is 5.57%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the metal stent is -0.81V and the corrosion current is 1.99×10 ^-4 A·cm ^-2 .

In this embodiment, the polished metal stent is sprayed with drug. The degradable polymer carrier in the degradable polymer drug-loaded coating is polylactic acid, the drug is rapamycin, the ratio of polymer carrier to drug is 3:1, and the sprayer advancement speed is 0.010mL/min. The wall thickness of the sprayed metal stent measured by the above detection method is 79 μm. In addition, the in vitro degradation test observed the accelerated generation of stent corrosion products, which had coated the entire substrate surface around 18 days.

Comparative example 1

The preparation method of the metal stent provided in this comparative example is basically the same as that of Embodiment 1, and the only difference is that the material of the stent is pure iron. Pure iron ingots are rolled to form plates, then rolled into strips, and annealed at the same time. The annealing temperature is 500°C. After annealing, the microstructure of the plate was observed at 2500X. There were no second phase particles on the surface. At the same time, no obvious grains are observed in this field of view, which may be due to the crushing of grains after rolling. After testing the performance with the above detection method, the measured mechanical properties are as follows: tensile strength is 258MPa and elongation is 31%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the plate of this composition after annealing is -0.59V, and the corrosion current is 8.26×10 ^-5 A·cm ^-2 . It can be seen that compared with degradable metal materials, pure iron has improved corrosion resistance but greatly reduced strength, which cannot meet the needs of use.

Comparative example 2

The preparation method of the metal stent provided in this comparative example is basically the same as that of Example 1, with the only difference being that the annealing temperature of the stent is 750°C. After annealing, the microstructure of the plate at 2500X was observed. The second phase particles on the surface decreased rapidly, with the number less than 100. At the same time, obvious large grains and smaller grains were observed in the field of view, which may be due to the annealing. The recrystallization temperature is increased, causing the originally broken grains to nucleate and grow again to produce new recrystallized grains. The large gap between grains may be due to the original second phase particles promoting the occurrence of recrystallization, resulting in the preferential nucleation of the second phase particles at a faster speed, resulting in size differences between grains. After testing the performance with the above detection method, the measured mechanical properties are as follows: tensile strength is 542MPa, and elongation is 0.96%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the plate with this composition after annealing is -0.62V, and the corrosion current is 8.94×10 ^-5 A·cm ^-2 . It can be seen that for the same kind of degradable metal materials, when the annealing temperature is too high, the recrystallization process occurs, which can reduce the second phase particles and enhance the corrosion resistance. However, at the same time, due to the larger grain size, the strength and elongation will decrease. It is greatly reduced and cannot meet the needs of use.

Comparative example 3

The preparation method of the metal stent provided in this comparative example is basically the same as that of Example 1. The only difference is that the tempering temperature of the stent is 100°C. The microstructure of the surface of the metal stent after tempering treatment at 2500X can be observed. Second phase particles. Compared with the plate after annealing, the distribution of second phase particles is more uniform and the number is increased. The analysis is due to the deepening of particle refinement after tempering. However, low-temperature tempering results in higher overall hardness and a lower elongation of 3.64%, which may cause the welding joint to break more easily, which is not conducive to subsequent actual use. After removing the surface oxide, the metal stent was electrolytically polished. The wall thickness of the polished metal stent measured by the above detection method was 71 μm. During the use of the metal stent produced by this method, it was found that the fractures at the welding joints increased significantly, which further verified the shortcomings of low-temperature tempering.

Comparative example 4

The preparation method of the metal stent provided in this comparative example is basically the same as that of Example 1, and the only difference is that the polishing time of the stent is 5 seconds. The wall thickness of the polished metal stent measured by the above detection method is 98 μm. The mechanical property curve of the metal stent measured by the above detection method is as follows: the tensile strength is 729MPa and the elongation is 4.11%. After testing the performance with the above detection method and converting the measured electrochemical polarization curve data, it was obtained that the corrosion potential of the metal stent is -0.89V and the corrosion current is 2.31×10 ^-4 A·cm ^-2 . This polishing method shortens the polishing time, increases the overall thickness of the stent, and improves the final mechanical strength. However, the overall surface has many burrs, which cannot be used for subsequent use without polishing.

Obviously, the above-mentioned embodiments are only examples for clear explanation and are not intended to limit the implementation. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. An exhaustive list of all implementations is neither necessary nor possible. The obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims (13)

1. A degradable metallic material, characterized in that the chemical composition of the degradable metallic material comprises, in mass percent:

c:0.05% -0.55%; si:0.07% -0.37%; mn:0.50% -1.80%; cr is less than or equal to 0.5%; ni is less than or equal to 0.5%; cu is less than or equal to 0.5%; p is less than or equal to 0.1 percent; s is less than or equal to 0.1 percent; the balance of Fe and unavoidable impurities;

the structure of the degradable metal material comprises a two-phase alloy, wherein the two-phase alloy comprises a first phase and a second phase distributed on the surface of the first phase, the particle size of the second phase is 0.5-7.0 mu m, and the number of particles under the 2500X visual field of a metallographic microscope is 700-1500.

2. The degradable metallic material according to claim 1, comprising the following chemical composition: c:0.47% -0.55%; si:0.17% -0.37%; mn:0.50% -0.80%; cr:0.02% -0.25%; ni:0.02% -0.25%; cu:0.02% -0.25%; p:0.05% -0.035%; s:0.05% -0.040%; the balance being Fe and unavoidable impurities.

3. The degradable metallic material according to claim 2, wherein the particle size in the second phase is 1.5 μm to 3.5 μm, and the number of particles is 200 to 400 under a 2500X field of a metallographic microscope.

4. The degradable metallic material according to claim 3, wherein the texture of the degradable metallic material further comprises a coating layer provided on the surface of the second phase.

5. The degradable metallic material according to claim 4, wherein the coating comprises a degradable carrier and a drug in a mass ratio of 1-4:1-4.

6. The degradable metallic material according to claim 5, wherein the degradable carrier is at least one of polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxyalkanoate, polyacrylate, polyethylene succinate, polycarbonate, polyether ester; and/or, the number of the groups,

the medicine is at least one of rapamycin and paclitaxel.

7. The method for preparing the degradable metal material according to any one of claims 1 to 6, comprising the steps of:

s1, smelting and molding the raw materials at 1100-1600 ℃ according to the proportion.

8. The method according to claim 7, further comprising step S2: and (3) rolling the steel ingot prepared in the step (S1) into a plate, annealing at 400-700 ℃ for 1-5 h, and manufacturing the annealed plate into a required implant structure.

9. The method of claim 8, further comprising step S3: tempering the implant structure prepared in the step S2, wherein the tempering temperature is above 150 ℃ and the tempering time is 0.5-10 h; and/or the number of the groups of groups,

Further comprising step S4: the implant structure produced in step S2 or step S3 is subjected to a polishing treatment.

10. The method according to claim 9, wherein the annealing temperature is 500-600 ℃; and/or, the tempering temperature is 550-650 ℃.

11. The method according to claim 10, wherein the step S4 is performed by electropolishing, and the polishing solution is prepared by mixing at least one of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, perchloric acid, hydrofluoric acid, citric acid, chromic acid, glacial acetic acid, and at least one of ethylene glycol and pure water;

and/or the temperature of the polishing solution is 40-90 ℃, and the polishing time is 10 s-10 min; and/or the number of the groups of groups,

further comprising step S5: coating the polished surface of the implant structure with a coating material.

12. The method according to claim 11, wherein in the step S4, the composition of the polishing liquid used includes: the mass ratio is 6-8: 3-4: 4-6 parts of phosphoric acid, sulfuric acid and ethylene glycol; and/or coating the coating material in the step S5 in a spraying manner, wherein the propelling speed of the spraying machine is 0.01-0.07 mL/min; and/or the number of the groups of groups,

the coating material comprises a degradable carrier and a drug, wherein the mass ratio of the degradable carrier to the drug is 1-4:1-4, the degradable carrier is at least one of polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxyalkanoate, polyacrylate, polyethylene succinate, polycarbonate and polyether ester, and the drug is at least one of rapamycin and paclitaxel.

13. Use of the degradable metallic material according to any one of claims 1 to 6 or the degradable metallic material produced by the production method according to any one of claims 7 to 12 for the production of vascular stents, intestinal implants, orthopedic implants.