A biomedical magnesium-based composite material, its preparation method and application

Abstract

The present invention discloses a biomedical magnesium-based composite material, a preparation method thereof and an application thereof, belonging to the technical field of biomedical materials. The preparation raw materials of the biomedical magnesium-based composite material include micron titanium particles coated with nano manganese and magnesium-zinc-zirconium alloy powder; the mass of the micron titanium particles is 1% to 5% of the magnesium-zinc-zirconium alloy powder, and the mass of the nano manganese is 1% to 2% of the magnesium-zinc-zirconium alloy powder; the magnesium-zinc-zirconium alloy powder contains 1 wt% to 6 wt% of zinc and 0.5 wt% to 1 wt% of zirconium, and the balance is magnesium; a nano-scale MnZn2 phase is formed in the biomedical magnesium-based composite material, and part of the manganese exists in a solid solution form in the magnesium alloy matrix formed by the magnesium-zinc-zirconium alloy powder; the magnesium-based composite material contains nano twins with a volume fraction of 5% to 15%. The magnesium-based composite material has relatively excellent mechanical properties, corrosion resistance and good biocompatibility, and can meet the requirements of clinical applications.

Description

Technical Field

[0001] The present invention relates to the technical field of biomedical materials, and in particular, to a biomedical magnesium-based composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Among biomedical implant materials, ceramic materials have potential risks under impact loads in the body due to their excessive brittleness; polymer materials often exhibit low strength, rigidity, and stability; metal materials have been widely used in the fields of orthopedics, oral repair, and cardiovascular treatment due to their good comprehensive mechanical properties. Among them, biomedical magnesium alloys have good biocompatibility and biosafety, and show great application prospects in implant medical devices such as bone scaffolds, cardiovascular stents, and bone nails.

[0003] Compared with other medical metals (such as stainless steel), the Young's modulus of magnesium alloys is closer to that of natural bone tissue, which helps to reduce the stress shielding effect during bone reconstruction and create a more favorable environment for bone healing and integration with surrounding tissues. Importantly, magnesium alloys can gradually degrade in the body during service until they are completely absorbed, skillfully meeting their clinical requirements as temporary substitutes; at the same time, the released magnesium ions during degradation can not only participate in various metabolic reactions in the body, but also play a key role in the activity, proliferation, and differentiation of bone cells. The above characteristics have changed the design and function of traditional medical metal implant devices and brought new medical effects, and are known as "revolutionary medical metal materials".

[0004] For the series of biomedical magnesium alloys developed currently, they have received extensive attention due to their excellent comprehensive properties, especially in the applications of orthopedic implants and cardiovascular stents (such as including cardiovascular stents, bone fixation materials, porous bone repair materials, wound suture materials, etc.), and substantial and encouraging research progress has been made. However, the standard electrode potential of magnesium is very low and it is prone to corrosion, and an effective protective oxide film cannot be formed, especially Cl in body fluids -It will accelerate the corrosion of magnesium alloys. The relatively fast degradation rate causes the implant material to corrode severely before the body heals, reducing the mechanical properties and stability of the material, rendering the material ineffective, and even potentially degrading completely. At the same time, the rapid corrosion of magnesium alloys is accompanied by a large release of hydrogen gas, which forms bubbles around the implant before it can diffuse and be absorbed. Although the bubbles can be removed by subcutaneous puncture, the formation of bubbles will to a certain extent affect the physiological functions of the tissues around the implant and the recovery treatment of the implant site. In addition, the excessively fast degradation rate will cause the local pH value of the body fluid near the implant to rise, posing potential hazards to human bone and tissue growth. For example, it can lead to protein deposition and inflammation in human tissues, or cause hemolysis and local osteolysis. It is precisely due to the relatively fast degradation rate of magnesium alloys and the resulting problems such as material failure, large-scale concentrated release of hydrogen gas, and pH value increase that restrict the application of magnesium alloys in biomedical clinics.

[0005] Therefore, alloying the matrix with elements such as magnesium, zinc, zirconium, and manganese required by the human body, and then regulating the microstructure of magnesium-based composites, improving the mechanical properties and corrosion rate in biological body fluids of magnesium-based composites, are the keys to the wide application of implant materials in the biomedical field.

[0006] In view of this, the present invention is specifically proposed. Summary of the Invention

[0007] The purpose of the present invention is to provide a biomedical magnesium-based composite material, its preparation method and application to solve or improve the above technical problems.

[0008] The present invention can be realized as follows:

[0009] In the first aspect, the present invention provides a biomedical magnesium-based composite material. The preparation raw materials of the biomedical magnesium-based composite material include micron titanium particles coated with nano manganese and magnesium-zinc-zirconium alloy powder;

[0010] In the micron titanium particles coated with nano manganese, the mass of the micron titanium particles is 1% - 5% of the magnesium-zinc-zirconium alloy powder, and the mass of the nano manganese is 1% - 2% of the magnesium-zinc-zirconium alloy powder; the magnesium-zinc-zirconium alloy powder contains 1wt% - 6wt% of zinc and 0.5wt% - 1wt% of zirconium, and the balance is magnesium;

[0011] The micron titanium particles coated with nano manganese and the magnesium alloy matrix formed by the magnesium-zinc-zirconium alloy powder form a nano-scale MnZn 2 phase at the bonding interface, and a part of the manganese in the micron titanium particles coated with nano manganese exists in the magnesium alloy matrix formed by the magnesium-zinc-zirconium alloy powder in a solid solution form; the biomedical magnesium-based composite material contains high-density nano-sized twins with a volume fraction of 5% - 15%.

[0012] In an alternative embodiment, the biomedical magnesium-based composite material has at least one of the following characteristics:

[0013] Characteristic 1: The average particle size of the magnesium-zinc-zirconium alloy powder is 50 μm to 80 μm;

[0014] Characteristic 2: The grains in the biomedical magnesium-based composite material are mainly in an equiaxed state after recrystallization, the grain size is 1.0 μm to 3.0 μm, and there is no obvious texture orientation;

[0015] Characteristic 3: In the micron titanium particles coated with nano manganese, the nano manganese is uniformly coated on the surface of the micron titanium particles.

[0016] In an alternative embodiment, the biomedical magnesium-based composite material further has at least one of the following characteristics:

[0017] Characteristic 4: The size of the twins contained in the biomedical magnesium-based composite material is 0.1 μm to 1 μm;

[0018] Characteristic 5: The tensile strength of the biomedical magnesium-based composite material is not less than 340 MPa;

[0019] Characteristic 6: The yield strength of the biomedical magnesium-based composite material is not less than 305 MPa;

[0020] Characteristic 7: The elastic modulus of the biomedical magnesium-based composite material is 41 GPa to 43 GPa;

[0021] Characteristic 8: The corrosion rate of the biomedical magnesium-based composite material under the condition of pH value of 7.4 to 7.6 is not higher than 0.18 mm / a.

[0022] In a second aspect, the present invention provides a preparation method of a biomedical magnesium-based composite material according to any one of the foregoing embodiments, including the following steps: ball-milling the micron titanium particles coated with nano manganese and the magnesium-zinc-zirconium alloy powder, and then performing spark plasma sintering and thermo-free forging deformation.

[0023] In an alternative embodiment, the preparation of the micron titanium particles coated with nano manganese includes: coating nano manganese powder on the surface of micron titanium particles by radio frequency plasma to obtain micron titanium particles coated with nano manganese;

[0024] Wherein, the average particle size of the nano manganese powder is 200 nm to 500 nm, the average particle size of the micron titanium particles is 10 μm to 20 μm, and the coating thickness is 0.1 μm to 1 μm.

[0025] In an alternative embodiment, the radio frequency plasma conditions include: the plasma power is 33 kW to 45 kW, the powder feeding rate is 12 g / min to 16 g / min, and the argon carrier gas flow rate is 70 L / min to 90 L / min.

[0026] In an alternative embodiment, the ball milling conditions include: a ball-to-material ratio of 20:1 to 30:1, a ball milling time of 1 h to 2 h, and a ball milling rotation speed of 180 rpm to 220 rpm.

[0027] In an alternative embodiment, the temperature of the spark plasma sintering is 500 °C to 520 °C, the pressure of the spark plasma sintering is 30 MPa to 40 MPa, the time of the spark plasma sintering is 5 min to 9 min, and air cooling is performed after the spark plasma sintering for temperature reduction.

[0028] In an alternative embodiment, the temperature of the hot free forging deformation is 300 °C to 350 °C, and the rate of the hot free forging deformation is 100 mm / min to 200 mm / min.

[0029] In a third aspect, the present invention provides a medical implant, and the preparation raw materials of the medical implant include the biomedical magnesium-based composite material of the foregoing embodiment.

[0030] The beneficial effects of the present invention include:

[0031] The biomedical magnesium-based composite material provided by the present invention is prepared from micron titanium particles coated with nano manganese and magnesium-zinc-zirconium alloy powder in a specific ratio. Among them, the nano manganese particles uniformly coated on the surface of the titanium particles preferentially combine with the zinc element in the magnesium-zinc-zirconium matrix alloy powder at the interface to in-situ form nano-scale MnZn 2 phase. The nano-scale MnZn 2 phase and the titanium particles act synergistically to hinder the movement of grain boundaries, significantly refining the grains of the composite material and promoting the formation of high-density and small-size twins. In addition, in addition to a part of the manganese element reacting in-situ at the interface to form the MnZn 2 phase, a part of it is also dissolved in the magnesium alloy matrix, playing an Orowan strengthening role and significantly improving the mechanical properties of the biomedical magnesium-based composite material.

[0032] At the same time, due to the good corrosion resistance of manganese itself, no severe galvanic corrosion phenomenon occurs between the matrix, and the overall corrosion resistance of the composite material can be significantly improved.

[0033] In the present invention, the mass of nano-manganese is specifically controlled to be 1% - 2% of the magnesium-zinc-zirconium alloy powder. The reason is that as the manganese content increases, the corrosion rate of the composite material first decreases significantly. With the addition of excessive manganese particles, the corrosion rate rebounds, but it is still better than that of the magnesium alloy without manganese addition. This is mainly because excessive manganese elements remain at the interface, promoting the formation of large-sized twins. The presence of large-sized twins will reduce the plasticity and ductility of the metal material, and cracks are likely to spread along the twin boundaries, resulting in easy fracture and fatigue damage of the material. In addition, the large-sized twins are a kind of defect-like existence, which is likely to promote local electrochemical reactions in the material and accelerate the corrosion of the material. The reason may be that the large-sized twin structure makes the material more likely to form electrochemical inhomogeneity in the corrosion environment, leading to accelerated local corrosion and severely reducing the service life of the biomedical material.

[0034] Therefore, selecting an appropriate amount of manganese element to coat the micron-sized titanium particles to reinforce the magnesium-zinc-zirconium alloy helps to improve the mechanical properties of the biomedical magnesium-based composite implant, improve the appropriate corrosion rate, and significantly improve the service life of the implant material in the biological environment. In addition, the biomedical magnesium-based composite material contains high-density nano-sized twins with a volume fraction of 5% - 15%, which is beneficial to controlling the degradation rate of the biomedical magnesium-based composite material within a suitable range.

[0035] The biomedical magnesium-based composite material provided by the present invention has a high yield strength, tensile strength, appropriate elastic modulus, and a low corrosion rate, and can be used as a biomedical implant. Brief Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 SEM image of the nano-manganese-coated micron-sized titanium particles prepared in Example 1;

[0038] Figure 2 Cross-sectional SEM image of the biomedical magnesium-based composite material prepared in Example 1;

[0039] Figure 3 Longitudinal-sectional SEM image of the biomedical magnesium-based composite material prepared in Example 1;

[0040] Figure 4 Transmission electron microscope image of the high-density and small-sized twins in the biomedical magnesium-based composite material prepared in Example 1;

[0041] Figure 5 TEM image of the nanoscale MnZn 2 phase in the biomedical magnesium-based composite material prepared in Example 1;

[0042] Figure 6 TEM image of the large-sized twins in the biomedical magnesium-based composite material prepared in Comparative Example 10. Detailed implementation manners

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. For those not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are followed. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0044] The biomedical magnesium-based composite material provided by the present invention, its preparation method, and applications will be specifically described below.

[0045] The present invention provides a biomedical magnesium-based composite material, and the raw materials for preparing the biomedical magnesium-based composite material include micron titanium particles coated with nano manganese and magnesium-zinc-zirconium alloy powder.

[0046] In the above-mentioned micron titanium particles coated with nano manganese, the mass of the micron titanium particles is 1% - 5% of the magnesium-zinc-zirconium alloy powder, such as 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc., and can also be other values within the range of 1% - 5%.

[0047] If the amount of the micron titanium particles is too small, it is not conducive to improving the strength of the magnesium-based composite material; if the amount of the micron titanium particles is too large, the number of particle-matrix interfaces is too large, which is not conducive to improving the plasticity of the composite material.

[0048] The mass of the nano manganese is 1% - 2% of the magnesium-zinc-zirconium alloy powder, such as 1%, 1.5%, or 2%, etc., and can also be other values within the range of 1% - 2%.

[0049] If the amount of the nano manganese is too small, the area of the coated micron titanium particles is less, which is not conducive to the reaction of manganese and zinc elements at the interface and cannot significantly improve the interface bonding situation; if the amount of the nano manganese is too large, it is easy to form agglomerates at the interface, which is not conducive to uniform coating and dispersion. At the same time, if the manganese content is too high, it is easy to form large-sized MnZn 2 phases and large-sized twins at the interface, which is not conducive to grain refinement, mechanical properties, and corrosion properties improvement. By adjusting the manganese element content in the biomedical magnesium-based composite material within the above range provided in this application, the grain and twin sizes can be refined more precisely, and the mechanical properties and degradation rate of the biomedical magnesium-based composite material can be controlled within a large range.

[0050] The magnesium-zinc-zirconium alloy powder contains 1 wt% - 6 wt% of zinc and 0.5 wt% - 1 wt% of zirconium, with the balance being magnesium. Among them, the content of zinc can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt% or 6 wt%, etc., or other values within the range of 1 wt% - 6 wt%. The content of zirconium can be 0.5 wt%, 0.8 wt% or 1 wt%, etc., or other values within the range of 0.5 wt% - 1 wt%.

[0051] In the biomedical magnesium-based composite material provided by the present invention, a nanoscale MnZn phase is formed at the bonding interface between the micron titanium particles coated with nano manganese and the magnesium alloy matrix formed by the magnesium-zinc-zirconium alloy powder, and a part of the manganese in the micron titanium particles coated with nano manganese exists in the magnesium alloy matrix formed by the magnesium-zinc-zirconium alloy powder in a solid solution form. 2 Moreover, in the biomedical magnesium-based composite material provided by the present invention, the biomedical magnesium-based composite material internally contains high-density twins with a volume fraction of 5% - 15% and a size of 0.1 μm - 1 μm. The twins with this content are beneficial to controlling the degradation rate of the biomedical magnesium-based composite material within a suitable range. It should be noted that the twins in the biomedical magnesium-based composite material refer to the existence of two or more crystals in the biomedical magnesium-based composite material, and their crystal structures are mirror images of each other. The formation of twins is due to a small energy difference in certain directions during the crystallization process, which causes the crystal planes to deflect a certain angle to form a twin boundary, thus forming twins. The nano-sized twin structure can increase the number of grain boundaries, and these grain boundaries can serve as a barrier for corrosive media to enter the interior of the material, thereby slowing down the corrosion process in the biological environment. Under the synergistic effect of nano-twins and low-angle grain boundaries, a stable passivation film is more likely to form on the surface of the material, further improving its corrosion resistance. At the same time, the nano-twin structure reduces the dislocation movement, making the plastic deformation more uniform and the stress concentration smaller when the material is subjected to external forces, thereby improving the mechanical properties of the material.

[0052] In some alternative embodiments, in the micron titanium particles coated with nano manganese, the nano manganese is uniformly coated on the surface of the micron titanium particles.

[0053] In some alternative embodiments, the average particle size of the magnesium-zinc-zirconium alloy powder can be 50 μm - 80 μm, such as 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm or 80 μm, etc., or other values within the range of 50 μm - 80 μm.

[0054]

[0055] ​If the average particle size of the magnesium-zinc-zirconium alloy powder is less than 50 μm, the magnesium alloy powder is relatively active, which is not conducive to ensuring the safety during the preparation processes of hot sintering and hot extrusion; if the average particle size of the magnesium-zinc-zirconium alloy powder is greater than 80 μm, the pores between the powders are relatively large, which is not conducive to obtaining a sintered dense and fine-grained magnesium-based composite material.

[0056] In some alternative embodiments, the grains in the biomedical magnesium-based composite material are mainly in the equiaxed state after recrystallization, and the grain size is 1.0 μm to 3.0 μm (such as 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm or 3.0 μm, etc.), and there is no obvious texture orientation. In some relatively typical embodiments, the grain size in the biomedical magnesium-based composite material is 1.5 μm to 2.1 μm, such as 1.5 μm, 1.8 μm or 2.1 μm, etc.

[0057] In some alternative embodiments, the tensile strength of the biomedical magnesium-based composite material provided by the present invention is not less than 340 MPa, and can be, for example, 340 MPa to 360 MPa, such as 342 MPa, 346 MPa or 358 MPa, etc.

[0058] In some alternative embodiments, the yield strength of the biomedical magnesium-based composite material provided by the present invention is not less than 305 MPa, and can be, for example, 305 MPa to 333 MPa, such as 305 MPa, 325 MPa or 333 MPa, etc.

[0059] In some alternative embodiments, the elastic modulus of the biomedical magnesium-based composite material provided by the present invention is 41 GPa to 43 GPa, and can be, for example, 41 GPa, 42 GPa or 43 GPa, etc. This elastic modulus is close to that of human bone, making it have good biocompatibility and being suitable for use as a medical implant.

[0060] In some alternative embodiments, the corrosion rate of the biomedical magnesium-based composite material provided by the present invention under the condition of pH value of 7.4 to 7.6 is not higher than 0.18 mm / a, and can be, for example, 0.12 mm / a to 0.18 mm / a, such as 0.12 mm / a, 0.15 mm / a or 0.18 mm / a, etc. This corrosion rate is relatively low and is suitable for use as a medical implant.

[0061] That is to say, the magnesium-based composite material provided by the present invention has high strength, appropriate elastic modulus and low corrosion rate, and can meet the requirements of clinical applications.

[0062] Correspondingly, the present invention also provides a preparation method of the above-mentioned biomedical magnesium-based composite material, including the following steps: ball-milling the micron titanium particles coated with nano manganese and the magnesium-zinc-zirconium alloy powder, and then performing spark plasma sintering and hot free forging deformation.

[0063] In some alternative embodiments, the preparation of the nano-manganese-coated micro-sized titanium particles includes: coating nano-manganese powder on the surface of micro-sized titanium particles by radio frequency plasma method to obtain nano-manganese-coated micro-sized titanium particles.

[0064] Among them, the average particle size of the nano-manganese powder can be 200 nm to 500 nm, such as 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm, etc., or other values within the range of 200 nm to 500 nm.

[0065] If the average particle size of the nano-manganese powder is less than 200 nm, the specific surface area is relatively large and it is easy to agglomerate, which is not conducive to uniform coating on the surface of micro-sized titanium particles, and the improvement of the interfacial effect is significantly reduced; if the average particle size of the nano-manganese powder is greater than 500 nm, the effect of coating micro-sized titanium is significantly reduced, and the MnZn 2 formed by the interfacial reaction and the twin crystal size are relatively large, which is not conducive to further refining the grain size, and the corrosion resistance will also be significantly reduced.

[0066] The average particle size of the micro-sized titanium particles can be 10 μm to 20 μm, such as 10 μm, 12 μm, 15 μm, 18 μm or 20 μm, etc., or other values within the range of 10 μm to 20 μm.

[0067] If the average particle size of the micro-sized titanium particles is greater than 20 μm, the pores between the powders are too large, which is not conducive to the densification of the composite material during sintering.

[0068] The coating thickness can be 0.1 μm to 1 μm, such as 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm or 1 μm, etc., or other values within the range of 0.1 μm to 1 μm.

[0069] It should be noted that if only the nano-manganese powder and the micro-sized titanium particles are simply mechanically mixed instead of being prepared in the form of manganese-coated titanium, a Ti-Mn alloy will be formed after mechanical ball milling, weakening the solid solution effect of the Mn element; and during the subsequent preparation process, nano-scale MnZn 2 phase cannot be formed at the interface, the effect of weakening the grain size is greatly reduced, the driving force for promoting the formation of small-sized twins is weakened, and the corrosion resistance decreases accordingly.

[0070] In some alternative embodiments, the radio frequency plasma conditions include: the plasma power is 33 kW to 45 kW, the powder feeding rate is 12 g / min to 16 g / min, and the argon carrier gas flow rate is 70 L / min to 90 L / min.

[0071] Among them, the plasma power can be 33kW, 35kW, 38kW, 40kW, 42kW or 45kW, etc., or other values within the range of 33kW to 45kW.

[0072] The powder feeding rate can be 12g / min, 13g / min, 14g / min, 15g / min or 16g / min, etc., or other values within the range of 12g / min to 16g / min.

[0073] The flow rate of argon carrier gas can be 70L / min, 75L / min, 80L / min, 85L / min or 90L / min, etc., or other values within the range of 70L / min to 90L / min.

[0074] In some alternative embodiments, the ball milling conditions include: the ball-to-material ratio is from 20:1 to 30:1, the ball milling time is from 1h to 2h, and the ball milling speed is from 180rpm to 220rpm.

[0075] Among them, the ball-to-material ratio can be 20:1, 22:1, 25:1, 28:1 or 30:1, etc., or other values within the range of 20:1 to 30:1.

[0076] The ball milling time can be 1h, 1.5h or 2h, etc., or other values within the range of 1h to 2h.

[0077] The ball milling speed can be 180rpm, 190rpm, 200rpm, 210rpm or 220rpm, etc., or other values within the range of 180rpm to 220rpm.

[0078] In some alternative embodiments, the temperature of spark plasma sintering is 500°C to 520°C, the pressure of spark plasma sintering is 30MPa to 40MPa, the time of spark plasma sintering is 0.5min to 0.9min, and air cooling is carried out after spark plasma sintering.

[0079] Among them, the temperature of spark plasma sintering can be 500°C, 505°C, 510°C, 515°C or 520°C, etc., or other values within the range of 500°C to 520°C.

[0080] If the temperature of spark plasma sintering is higher than 520°C, it is easy to cause oxidation of metallic magnesium, accelerate the crystal growth rate, lead to coarsening and growth of crystal grains, and more pores are likely to form inside the metal material, affecting the mechanical properties and corrosion resistance of the implant material.

[0081] The time of spark plasma sintering can be 5min, 6min, 7min, 8min or 9min, etc., or other values within the range of 5min to 9min.

[0082] In some alternative embodiments, the temperature of the hot free forging deformation is 300°C to 350°C, and the rate of the hot free forging deformation is 100 mm / min to 200 mm / min.

[0083] Among them, the temperature of the hot free forging deformation can be 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C or 350°C, etc., or other values within the range of 300°C to 350°C.

[0084] The above-mentioned hot free forging deformation temperature can obtain fine equiaxed crystal structures after dynamic recrystallization, and the texture orientation is significantly weakened.

[0085] If the temperature of the hot free forging deformation is too low, it is not conducive to the thermoplastic deformation of the composite material, and the work hardening phenomenon is serious; if the temperature of the hot free forging deformation is too high, it is easy to cause serious grain coarsening, and oxygen and other oxidizing gases in the magnesium alloy penetrate into the voids between grains to form eutectics of fusible oxides, destroying the connection between grains and resulting in a sharp decrease in the plasticity of the material.

[0086] The rate of the hot free forging deformation can be 100 mm / min, 120 mm / min, 150 mm / min, 180 mm / min or 200 mm / min, etc., or other values within the range of 100 mm / min to 200 mm / min.

[0087] It should be noted that the hot free forging deformation process is a favorable stress state of compressive stress, so it has obvious advantages in processing metals with poor workability. By adopting this uniform large plastic deformation method, it helps to refine the grain size and introduce a high density of twins, thereby significantly improving the mechanical properties of the composite material.

[0088] Continuing from the above, micron-sized titanium particles uniformly coated with nano-manganese were successfully prepared by using the radio frequency plasma method. The obtained nano-manganese-coated micron-sized titanium particles were ball-milled with the magnesium-zinc-zirconium alloy under the above conditions. The manganese element uniformly coated on the surface of the titanium particles can react with the matrix magnesium alloy at the interface to in-situ form fine nano-scale MnZn 2 phase. The cooperation of this phase with the titanium particles helps to refine the average grain size of the composite material. At the same time, a part of the manganese element enters the magnesium alloy matrix in a solid solution form, promoting the formation of high-density, nano-sized twins, which helps to improve the corrosion resistance of the biomedical magnesium-based composite material and significantly improve the service life of the implanted material in the biological environment. In addition, the elastic modulus of this biomedical magnesium-based composite material is moderate, which is similar to the elastic modulus of bone, avoiding the occurrence of stress concentration fracture failure of the implanted material.

[0089] In addition, the present invention also provides a medical implant, and the preparation raw materials of the medical implant include the above-mentioned biomedical magnesium-based composite material.

[0090] Exemplarily, the medical implant may include a cardiovascular stent, a bone fixation material, a porous bone repair material, a wound suture material, etc.

[0091] The features and properties of the present invention will be further described in detail below in conjunction with embodiments.

[0092] Example 1

[0093] This example provides a biomedical magnesium-based composite material, and its preparation method includes:

[0094] S1: Using a radio frequency plasma device to coat nano-manganese powder on the surface of micron-sized titanium particles to obtain nano-manganese-coated micron-sized titanium particles.

[0095] Among them, the average particle size of the nano-manganese powder is 200 nm, the average particle size of the micron-sized titanium particles is 10 μm, and the coating thickness is 0.5 μm. The plasma power is 40 kW, the powder feeding rate is 14 g / min, and the argon carrier gas flow rate is 80 L / min.

[0096] S2: Ball-milling the nano-manganese-coated micron-sized titanium particles with Mg-Zn-Zr alloy powder.

[0097] Among them, the mass of the micron-sized titanium particles is 5.0% of the Mg-Zn-Zr alloy powder, and the mass of the nano-manganese is 2.0% of the Mg-Zn-Zr alloy powder. The Mg-Zn-Zr alloy powder contains 4 wt% of zinc and 0.5 wt% of zirconium, and the balance is magnesium, denoted as Mg4Zn0.5Zr alloy powder. The average particle size of the Mg-Zn-Zr alloy powder is 60 μm. The ball-to-powder ratio is 25:1, the ball-milling speed is 180 r / min, and the ball-milling time is 1.0 h.

[0098] S3: Subjecting the ball-milled material to spark plasma sintering, and then air-cooling it to room temperature.

[0099] Among them, the temperature of the spark plasma sintering is 500 °C, the pressure of the spark plasma sintering is 40 MPa, and the time of the spark plasma sintering is 5 min.

[0100] S4: Subjecting the sintered part after spark plasma sintering to hot free forging deformation to obtain a biomedical magnesium-based composite material.

[0101] Among them, the temperature of the hot free forging deformation is 350 °C, and the rate of the hot free forging deformation is 100 mm / min.

[0102] Example 2

[0103] This embodiment provides a biomedical magnesium-based composite material, and its preparation method includes:

[0104] S1: Using a radio frequency plasma device to coat nano-manganese powder on the surface of micron-sized titanium particles to obtain nano-manganese-coated micron-sized titanium particles.

[0105] Among them, the average particle size of the nano-manganese powder is 400 nm, the average particle size of the micron-sized titanium particles is 15 μm, and the coating thickness is 0.1 μm. The plasma power is 33 kW, the powder feeding rate is 12 g / min, and the argon carrier gas flow rate is 70 L / min.

[0106] S2: Ball-milling the nano-manganese-coated micron-sized titanium particles with magnesium-zinc-zirconium alloy powder.

[0107] Specifically, the mass of the micron-sized titanium particles is 3.0% of the magnesium-zinc-zirconium alloy powder, and the mass of the nano-manganese is 1.5% of the magnesium-zinc-zirconium alloy powder. The magnesium-zinc-zirconium alloy powder contains 3 wt% of zinc and 0.8 wt% of zirconium, and the balance is magnesium, denoted as Mg3Zn0.8Zr alloy powder. The average particle size of the magnesium-zinc-zirconium alloy powder is 70 μm. The ball-to-powder ratio is 20:1, the ball-milling rotation speed is 200 r / min, and the ball-milling time is 2 h.

[0108] S3: Subjecting the ball-milled material to spark plasma sintering, and then air-cooling it to room temperature.

[0109] Among them, the temperature of the spark plasma sintering is 510 °C, the pressure of the spark plasma sintering is 30 MPa, and the time of the spark plasma sintering is 6 min.

[0110] S4: Subjecting the sintered part after spark plasma sintering to hot free forging deformation to obtain a biomedical magnesium-based composite material.

[0111] Among them, the temperature of the hot free forging deformation is 300 °C, and the rate of the hot free forging deformation is 200 mm / min.

[0112] Example 3

[0113] This embodiment provides a biomedical magnesium-based composite material, and its preparation method includes:

[0114] S1: Using a radio frequency plasma device to coat nano-manganese powder on the surface of micron-sized titanium particles to obtain nano-manganese-coated micron-sized titanium particles.

[0115] Among them, the average particle size of the nano-manganese powder is 500 nm, the average particle size of the micron-sized titanium particles is 20 μm, and the coating thickness is 1 μm. The plasma power is 45 kW, the powder feeding rate is 16 g / min, and the argon carrier gas flow rate is 90 L / min.

[0116] S2: Ball mill the micron titanium particles coated with nano manganese and the magnesium-zinc-zirconium alloy powder.

[0117] Specifically, the mass of the micron titanium particles is 1.0% of the magnesium-zinc-zirconium alloy powder, and the mass of the nano manganese is 1.0% of the magnesium-zinc-zirconium alloy powder. The magnesium-zinc-zirconium alloy powder contains 2 wt% of zinc and 1 wt% of zirconium, and the balance is magnesium, denoted as Mg2Zn1Zr alloy powder. The average particle size of the magnesium-zinc-zirconium alloy powder is 80 μm. The ball-to-material ratio is 30:1, the ball milling speed is 220 r / min, and the ball milling time is 1 h.

[0118] S3: Carry out spark plasma sintering on the ball-milled material, and then air-cool it to room temperature.

[0119] Among them, the temperature of the spark plasma sintering is 520 °C, the pressure of the spark plasma sintering is 35 MPa, and the time of the spark plasma sintering is 9 min.

[0120] S4: Carry out hot free forging deformation on the sintered part after spark plasma sintering to obtain a biomedical magnesium-based composite material.

[0121] Among them, the temperature of the hot free forging deformation is 325 °C, and the rate of the hot free forging deformation is 150 mm / min.

[0122] Comparative Example 1

[0123] The difference between this comparative example and Example 1 is that in S1, the nano manganese powder and the micron titanium particles are directly mechanically mixed without coating treatment.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Example 1 is that in S1, Cu is used instead of Mn.

[0126] Comparative Example 3

[0127] The difference between this comparative example and Example 1 is that in S1, the average particle size of the nano manganese powder is 10 nm.

[0128] Comparative Example 4

[0129] The difference between this comparative example and Example 1 is that in S1, the average particle size of the nano manganese powder is 600 nm.

[0130] Comparative Example 5

[0131] The difference between this comparative example and Example 1 is that in S1, the average particle size of the micron titanium particles is 5 μm.

[0132] Comparative Example 6

[0133] The difference between this comparative example and Example 1 is that in S1, the average particle size of the micron titanium particles is 50 μm.

[0134] Comparative Example 7

[0135] The difference between this comparative example and Example 1 is that in S2, the mass of the micron titanium particles is 0.5% of the magnesium-zinc-zirconium alloy powder.

[0136] Comparative Example 8

[0137] The difference between this comparative example and Example 1 is that in S2, the mass of the micron titanium particles is 10% of the magnesium-zinc-zirconium alloy powder.

[0138] Comparative Example 9

[0139] The difference between this comparative example and Example 1 is that in S2, the mass of the nano manganese is 0.5% of the magnesium-zinc-zirconium alloy powder.

[0140] Comparative Example 10

[0141] The difference between this comparative example and Example 1 is that in S2, the mass of the nano manganese is 5% of the magnesium-zinc-zirconium alloy powder.

[0142] Comparative Example 11

[0143] The difference between this comparative example and Example 1 is that in S2, the average particle size of the magnesium-zinc-zirconium alloy powder is 20 μm.

[0144] Comparative Example 12

[0145] The difference between this comparative example and Example 1 is that in S2, the average particle size of the magnesium-zinc-zirconium alloy powder is 100 μm.

[0146] Comparative Example 13

[0147] The difference between this comparative example and Example 1 is that in S4, the temperature of the spark plasma sintering is 550 °C.

[0148] Comparative Example 14

[0149] The difference between this comparative example and Example 1 is that in S5, the temperature of the hot free forging deformation is 280 °C.

[0150] Comparative Example 15

[0151] The difference between this comparative example and Example 1 is that in S5, the temperature of the hot free forging deformation is 380 °C.

[0152] Test Example

[0153] ①. Taking the biomedical magnesium-based composite materials prepared in Example 1 and Comparative Example 10 as an example, their morphology was detected, and the MnZn formed by them2 Transmission crystal fine structure characterization was carried out on the phase and high-density twins, and the results are as follows Figures 1 to 6 and shown in Table 1

[0154] It can be seen from Figures 1 to 5 that in the biomedical magnesium-based composite material prepared in Example 1 (denoted as Ti@Mn / Mg4Zn0.5Zr), a part of manganese elements form fine MnZn 2 phases at the grain boundaries. The nano-scale rectangular phases and nano-titanium particles act synergistically, which is more conducive to hindering the movement of grain boundaries. At the same time, a part of the manganese particles dissolved in the magnesium alloy matrix are entangled with dislocations, causing stress concentration, which helps to generate high-density and small-sized twins, and is beneficial to greatly improve the mechanical properties and bio-corrosion resistance rate of the biomedical magnesium-based composite material

[0155] Among them, it can be seen from Figure 1 that nano-manganese elements are uniformly coated on the surface of micron-sized titanium particles. The titanium particles, as dispersed carriers, help to reduce the agglomeration of nano-manganese elements

[0156] It can be seen from Figures 2 to 4 that in this biomedical magnesium-based composite material, micron-sized titanium particles are mainly distributed at the grain boundaries, and fine MnZn 2 phases are formed at the interface, and many fine manganese phases precipitate inside the grains

[0157] It can be seen from Figure 5 that there are high-density and small-sized twins inside this biomedical magnesium-based composite material. The formation of twins will cause a certain amount of deformation, thereby alleviating local stress concentration and playing a role in coordinating metal plastic deformation; at the same time, the generation of small-sized twins will induce the lattice structure to rotate to form new crystal orientations, which is beneficial to activating more types of slip systems. Moreover, the intersecting twin boundaries divide the parent crystal into several fine grains, inducing the Hall-Petch effect and hindering the movement of dislocations. The pile-up of dislocations at the grain boundaries causes stress concentration, which may provide new nucleation sites for twins or secondary twins. The combined action of these mechanisms helps to improve the mechanical properties and bio-corrosion resistance

[0158] It can be seen from Figure 6It can be seen that for the biomedical magnesium-based composite material prepared in Comparative Example 10, due to the excessive amount of manganese element, the formation of large-sized twins occurred. The large-sized twins were arranged in parallel, showing obvious texture orientation. Large-sized twins are prone to form stress concentration at grain boundaries when stressed, leading to cracks and fractures. The defects during the growth process of large-sized twins will significantly weaken the toughness of the material, making the internal structure of the material uneven and affecting the overall mechanical properties of the material. The grain boundary stability of large-sized twins is poor, which easily leads to preferential corrosion at grain boundaries. Grain boundaries are the weak links in materials. The large grain boundary area of large-sized twins increases the opportunity for corrosion medium to penetrate and attack, thus accelerating the biological corrosion process.

[0159] ② The mechanical properties and biocorrosion resistance of the biomedical magnesium-based composite materials prepared in Examples 1 to 3 and Comparative Examples 1 to 15 were tested, and the results are shown in Table 1.

[0160] Among them, the tensile test was to apply a tensile force to the material sample under standard room temperature conditions until it broke, measure its stress-strain relationship, and conduct the test according to the standard of 《GB / T 228.1-2010》, and calculate the yield strength and tensile strength; the elastic modulus was calculated by the ratio of stress to strain within the elastic deformation range of the tensile test; the biocorrosion resistance was tested according to the standard of 《YY / T 1434-2016》 in a simulated human environment (pH value of 7.4 - 7.6).

[0161] Table 1 Test Results

[0162]

[0163] As can be seen from Table 1, the biomedical magnesium-based composite material prepared by the method provided by the present invention has a relatively high yield strength, tensile strength, appropriate elastic modulus, and relatively appropriate corrosion rate.

[0164] In summary, the biomedical magnesium-based composite material provided by the present invention is a biomedical magnesium-based composite material with a high-density twin structure and controllable degradation. Among them, titanium particles help to improve the strength and plasticity of the magnesium matrix. At the same time, a part of the manganese element on the surface of the titanium particles can react with the matrix to form fine MnZn 2 phase at the interface, which helps to refine the grains; another part of the manganese element is dissolved in the magnesium alloy matrix, promoting the formation of high-density nanoscale twins and improving the overall mechanical properties and biocorrosion resistance of the alloy. The biomedical magnesium-based composite material provided by the present invention has a relatively high yield strength, tensile strength, appropriate elastic modulus, and relatively appropriate biocorrosion rate, and can be used as a medical implant.

[0165] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A biomedical magnesium-based composite material, characterized in that: The raw materials for preparing the biomedical magnesium-based composite material include nano-manganese-coated micron titanium particles and magnesium-zinc-zirconium alloy powder; In the nano-manganese-coated micron titanium particles, the mass of the micron titanium particles is 1% to 5% of the magnesium-zinc-zirconium alloy powder, and the mass of the nano-manganese is 1% to 2% of the magnesium-zinc-zirconium alloy powder; the magnesium-zinc-zirconium alloy powder contains 1wt% to 6wt% zinc and 0.5wt% to 1wt% zirconium, with the remainder being magnesium; The nano-manganese coated micron titanium particles and the magnesium alloy matrix formed by the magnesium-zinc-zirconium alloy powder form a nano-scale MnZn2 phase at the bonding interface, and part of the manganese in the nano-manganese coated micron titanium particles exists in the magnesium alloy matrix formed by the magnesium-zinc-zirconium alloy powder in the form of solid solution; the biomedical magnesium-based composite material contains high-density nano-sized twins with a volume fraction of 5% to 15%; the size of the twins contained in the biomedical magnesium-based composite material is 0.1μm to 1μm; the average particle size of the nano-manganese powder is 200nm to 500nm; the average particle size of the magnesium-zinc-zirconium alloy powder is 50μm to 80μm; the average particle size of the micron titanium particles is 10μm to 20μm; The preparation of the biomedical magnesium-based composite material comprises: ball milling nano-manganese-coated micron titanium particles and magnesium-zinc-zirconium alloy powder, followed by spark plasma sintering and hot free forging deformation; the spark plasma sintering temperature is 500° C. to 520° C.; the hot free forging deformation temperature is 300° C. to 350° C.

2. The biomedical magnesium-based composite material according to claim 1, characterized in that: The biomedical magnesium-based composite material has at least one of the following characteristics: Feature 1: The grains in the biomedical magnesium-based composite material are mainly in an equiaxed state after recrystallization, with a grain size of 1.0 μm to 3.0 μm and no obvious texture orientation; Feature 2: In the nano-manganese coated micron titanium particles, nano-manganese is uniformly coated on the surface of the micron titanium particles.

3. The biomedical magnesium-based composite material according to claim 2, characterized in that: The biomedical magnesium-based composite material also has at least one of the following characteristics: Feature 3: The tensile strength of the biomedical magnesium-based composite material is not less than 340 MPa; Feature 4: The yield strength of the biomedical magnesium-based composite material is not less than 305 MPa; Feature 5: The elastic modulus of the biomedical magnesium-based composite material is 41 GPa to 43 GPa; Feature 6: The corrosion rate of the biomedical magnesium-based composite material is no more than 0.18 mm / a under a pH value of 7.4 to 7.

6.

4. A method for preparing a biomedical magnesium-based composite material according to any one of claims 1 to 3, characterized in that: The following steps are involved: The nano-manganese coated micron titanium particles were ball milled with magnesium-zinc-zirconium alloy powder, followed by spark plasma sintering and hot free forging deformation; The temperature of spark plasma sintering is 500℃~520℃; the temperature of hot free forging deformation is 300℃~350℃.

5. The preparation method according to claim 4, characterized in that: The preparation of the nano-manganese coated micron titanium particles comprises: coating the nano-manganese powder on the surface of the micron titanium particles by radio frequency plasma to obtain the nano-manganese coated micron titanium particles; Among them, the coating thickness is 0.1μm~1μm.

6. The preparation method according to claim 5, characterized in that: The RF plasma conditions include: plasma power of 33 kW to 45 kW, powder feeding rate of 12 g / min to 16 g / min, and argon carrier gas flow rate of 70 L / min to 90 L / min.

7. The preparation method according to claim 4, characterized in that: The ball milling conditions include: a ball-to-material ratio of 20:1 to 30:1, a ball milling time of 1 h to 2 h, and a ball milling speed of 180 rpm to 220 rpm.

8. The preparation method according to claim 4, characterized in that: The pressure of spark plasma sintering is 30MPa~40MPa, the time of spark plasma sintering is 5min~9min, and air cooling is performed after spark plasma sintering.

9. The preparation method according to claim 4, characterized in that: The hot free forging deformation rate is 100mm / min~200mm / min‌.

10. A medical implant, characterized in that: The raw material for preparing the medical implant comprises the biomedical magnesium-based composite material according to claim 1.

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