High-corrosion-resistance biomedical degradable magnesium-based composite material and solid-phase additive preparation method thereof

Abstract

The invention discloses a high-corrosion-resistance biomedical degradable magnesium-based composite material and a solid-phase additive preparation method thereof, and belongs to the technical field of biomedical materials. The preparation method of the solid-phase additive comprises the following steps: dissolving a nano reinforced phase and polylactic acid-glycolic acid in a solvent, performing ultrasonic dispersion, stirring to form a uniform suspension, and defoaming to obtain composite slurry; the magnesium alloy foil is vertically immersed in the composite slurry, and drying is performed after multiple times of pulling, so that the magnesium alloy foil coated with a composite layer is formed; the magnesium alloy foil coated with the composite coating is cut into strips, and magnesium alloy wires are manufactured through multiple times of cold drawing; the magnesium alloy wire is used as a raw material, layer-by-layer deposition is carried out on a magnesium alloy substrate by adopting a wire filling stirring friction additive manufacturing technology, and the high-corrosion-resistance biomedical degradable magnesium-based composite material is prepared. The problems of magnesium base material oxidation and grain coarsening caused by high temperature are avoided, the tensile strength of the material is high, and the corrosion resistance is excellent.

Description

Technical Field

[0001] The present invention relates to the technical field of biomedical materials, and particularly relates to a highly corrosion-resistant biomedical degradable magnesium-based composite material and a solid-phase additive manufacturing method therefor. Background Art

[0002] The information disclosed in the background art of the present invention is only intended to enhance the overall understanding of the present invention, and is not necessarily regarded as an admission or an indication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] In recent years, the application demand for biomedical degradable materials in the fields of orthopedic fixation, cardiovascular stents, etc. has been continuously increasing, driving the innovation of material design and preparation technologies. Although traditional medical metal materials such as stainless steel and titanium alloy have excellent mechanical properties, their non-degradable characteristics force patients to bear the risk of secondary surgery. On the other hand, degradable polymer materials such as polylactic acid have defects such as insufficient mechanical strength and inflammatory reactions caused by degradation products. Magnesium alloys have become ideal candidate materials due to their density close to that of human bones, good biocompatibility, and degradable characteristics. However, their excessive degradation in the body fluid environment will lead to premature loss of mechanical support and tissue irritation caused by the increase of local pH value, which severely restricts the clinical application process.

[0004] Although certain progress has been made in the prior art in constructing magnesium-based composites by introducing nano / micron reinforcement phases to delay the degradation rate, there are still multiple technical bottlenecks in the material preparation process: on the one hand, traditional casting and powder metallurgy processes need to go through a high-temperature melting process, which is extremely easy to cause oxidation of the magnesium matrix and grain coarsening, resulting in the simultaneous decline of the corrosion resistance and mechanical properties of the material; on the other hand, although liquid-phase additive manufacturing technologies such as selective laser melting can achieve structure customization, it is also difficult to avoid the problem of thermal damage to the magnesium matrix in the high-temperature deposition environment, and the reinforcement phases are prone to agglomeration due to interface incompatibility or solvent volatilization in the molten pool, resulting in weakening of the interfacial bonding strength of the composite material. Therefore, how to provide a preparation method for biomedical degradable magnesium-based composites with excellent mechanical properties and high corrosion resistance is still an urgent problem to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a highly corrosion-resistant biomedical degradable magnesium-based composite material and a solid-phase additive manufacturing method therefor. The solid-phase additive manufacturing method provided by the present invention avoids the problems of oxidation of the magnesium substrate and grain coarsening caused by high temperature. There is a high interfacial bonding strength between the nano-reinforcement phase and the magnesium alloy, and the obtained magnesium-based composite material has high corrosion resistance and high tensile strength.

[0006] In the first aspect, the present invention provides a solid-phase additive manufacturing method for a highly corrosion-resistant biomedical degradable magnesium-based composite material, including the following steps:

[0007] S1. Dissolve the nano-reinforcing phase and poly(lactic-co-glycolic acid) in a solvent, ultrasonically disperse and then stir to form a uniform suspension, and degas to obtain a composite slurry;

[0008] S2. Vertically immerse the magnesium alloy foil in the composite slurry, lift it multiple times and then dry it to form a magnesium alloy foil coated with a composite layer;

[0009] S3. Cut the magnesium alloy foil coated with the composite coating into strips, and make magnesium alloy wires through multiple cold drawing processes;

[0010] S4. Using the magnesium alloy wire as a raw material, adopt the wire-filled friction stir additive manufacturing technology to deposit layer by layer on a magnesium alloy substrate to obtain the high-corrosion-resistant biodegradable magnesium-based composite material.

[0011] In a second aspect, the present invention provides a high-corrosion-resistant biodegradable magnesium-based composite material prepared by the above solid-phase additive manufacturing method.

[0012] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0013] (1) The present invention uses poly(lactic-co-glycolic acid) (PLGA) as a dispersion medium and a temporary binder for the nano-reinforcing phase, and combines the ultrasonic-mechanical stirring synergistic process to ensure the uniform dispersion of the reinforcing phase and better combination with the magnesium substrate, avoiding the early failure caused by interface debonding in traditional composite materials.

[0014] (2) From impregnation drying, cold drawing forming to solid-phase additive manufacturing, the present invention avoids the problems of magnesium substrate oxidation and grain coarsening caused by high temperature throughout the process. The tensile strength of the material is improved compared with traditional cast magnesium alloys, and at the same time, a uniformly dispersed reinforcing phase is obtained to improve the corrosion resistance and mechanical properties of the magnesium alloy.

[0015] (3) The cold drawing and solid-phase additive manufacturing (wire-filled friction stir additive manufacturing) of the present invention support continuous production, the material utilization rate is increased compared with traditional cutting processing, and the shape and mechanical properties can be customized according to patient data, and the structure can be flexibly prepared to meet the personalized medical needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The schematic diagram of the specification drawings constituting a part of the present invention is used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a schematic diagram of the preparation process of the high-corrosion-resistant biodegradable magnesium-based composite material in the specific embodiment of the present invention;

[0018] Figure 2 It is the microstructure picture of the high corrosion-resistant biodegradable magnesium-based composite material of Example 1 of the present invention;

[0019] Figure 3 It is the scanning picture of the reinforcing particles of the high corrosion-resistant biodegradable magnesium-based composite material of Example 1 of the present invention;

[0020] Figure 4 It is the microstructure picture of the high corrosion-resistant biodegradable magnesium-based composite material of Example 2 of the present invention;

[0021] Figure 5 It is the scanning picture of the reinforcing particles of the high corrosion-resistant biodegradable magnesium-based composite material of Example 2 of the present invention;

[0022] Figure 6 It is the corrosion morphology diagram of the high corrosion-resistant biodegradable magnesium-based composite material of Example 1 of the present invention;

[0023] Figure 7 It is the corrosion morphology diagram of the high corrosion-resistant biodegradable magnesium-based composite material of Example 2 of the present invention. Detailed implementation manners

[0024] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0025] The present invention provides a solid-phase additive manufacturing method for a high corrosion-resistant biodegradable magnesium-based composite material. The schematic diagram of the preparation process is as Figure 1 shown, and it includes the following steps:

[0026] S1. Dissolve the nano-reinforcing phase and polylactic acid-glycolic acid in a solvent, stir after ultrasonic dispersion to form a uniform suspension, and de-bubble to obtain a composite slurry;

[0027] S2. Vertically immerse the magnesium alloy foil into the composite slurry, lift it multiple times and then dry it to form a magnesium alloy foil coated with a composite layer;

[0028] S3. Cut the magnesium alloy foil coated with the composite coating into strips, and make magnesium alloy wires through multiple cold drawing processes;

[0029] S4. Using the magnesium alloy wire as raw material, adopt the wire-fed friction stir additive manufacturing technology to deposit layer by layer on the magnesium alloy substrate to obtain the high corrosion-resistant biodegradable magnesium-based composite material.

[0030] In the present invention, first, polylactic acid-glycolic acid (PLGA) is used as a dispersion medium and a temporary binder for the nano-reinforcing phase so that the nano-reinforcing particles can be conveniently and uniformly coated on the magnesium alloy foil subsequently. Combining the ultrasonic-mechanical stirring synergistic process ensures the uniform dispersion of the reinforcing phase, which is beneficial for better bonding with the magnesium alloy foil and avoiding early failure caused by interfacial debonding. PLGA is used because it is randomly polymerized from lactic acid and glycolic acid, and is a biodegradable functional polymer organic compound with good biocompatibility, non-toxicity, and good properties of forming capsules and films.

[0031] In the present invention, taking the magnesium alloy foil as the raw material, through impregnation drying, cold drawing forming, and solid-phase additive manufacturing (wire-filled friction stir additive manufacturing), the problems of oxidation and grain coarsening of the magnesium substrate caused by high temperature are avoided throughout the process. The tensile strength of the material is increased compared with traditional cast magnesium alloys, and at the same time, uniformly dispersed reinforcing phases are obtained to improve the corrosion resistance and mechanical properties of the magnesium alloy. In addition, cold drawing and solid-phase additive manufacturing support continuous production, the material utilization rate is increased compared with traditional machining, and the shape and mechanical properties can be customized according to patient data, and the structure can be flexibly prepared to meet the personalized medical needs.

[0032] In the present invention, no special restrictions are imposed on the specific type of magnesium alloy of the magnesium alloy foil, and the commonly used magnesium alloy types in the art can be adopted.

[0033] In the present invention, the nano-reinforcing phase is selected from one or more of hydroxyapatite, Y2O3, ZrO2, CaO, SiC, or TiC; due to its high specific surface area and interfacial effect, it can effectively fill the grain boundary defects of the magnesium matrix and block the diffusion path of the corrosion medium; at the same time, as a physical barrier, it delays the degradation rate of the magnesium matrix and improves the corrosion resistance. The particle size of the nano-reinforcing phase is 20 - 500 nm, ensuring that the reinforcing phase can be uniformly dispersed (avoiding agglomeration) and has sufficient mechanical bearing capacity (too small nano-particles are easily wrapped by the matrix and lose the strengthening effect).

[0034] In the polylactic acid-glycolic acid of the present invention, the molar ratio of polylactic acid to glycolic acid is (70 - 85):(15 - 30) to balance the degradation rate and mechanical strength of PLGA. Glycolic acid (GA) can increase the chain segment flexibility and accelerate the degradation rate, but the mechanical strength decreases; while lactic acid can increase the crystallinity and thus enhance the mechanical properties. The appropriate ratio ensures that PLGA has both temporary bonding strength (in the cold drawing stage) and controllable degradability (gradually releasing the reinforcing phase after implantation) in the coating.

[0035] In the present invention, the dosage ratio of the nano-reinforcing phase, polylactic acid-glycolic acid, and the solvent is 1 g:(5 - 10) g:(30 - 80) mL, and the solvent is selected from one or more of acetone, tetrahydrofuran, or ethyl acetate, ensuring the formation of a uniform composite slurry and being easy to dry to form a composite layer.

[0036] In step S1 of the present invention, the time of ultrasonic dispersion is 10 - 60 min, the power of ultrasonic is 100 - 800 W; the rotation speed of stirring is 50 - 800 rpm, and the time of stirring is 10 - 60 min. Ultrasonic cavitation generates micro-jet through high-frequency vibration to break the agglomerates of nanoparticles; the mechanical shear force of continuous stirring maintains the dynamic stability of the suspension to avoid sedimentation. The dual action ensures that the particle agglomeration size < 1000 nm and the absolute value of Zeta potential > 30 mV, guaranteeing the stability of the composite slurry.

[0037] The present invention does not impose special restrictions on the defoaming process. Preferably, the present invention performs vacuum defoaming for 10 - 60 min.

[0038] In the present invention, in step S2, before the magnesium alloy foil is vertically immersed in the composite slurry, it further includes a step of pretreating the magnesium alloy foil. The pretreatment includes sequentially cleaning with acetone, nitric acid, and water, and then drying to obtain it, so as to remove impurities and oxide layers.

[0039] The present invention uses gravity to uniformly spread the composite slurry along the surface of the foil, avoiding the retention of air bubbles during horizontal impregnation; through the "impregnation - lifting - re - impregnation" cycle, the thickness of the composite layer is gradually increased to 5 - 30 μm layer by layer, while discharging the interfacial air bubbles and improving the density of the coating.

[0040] In step S2 of the present invention, the thickness of the magnesium alloy foil is 0.1 - 2.0 mm; the drying is carried out at 40 - 60 °C under the protection of inert gas; the inert gas is selected from one or more of nitrogen or argon; drying at a lower temperature prevents the thermal decomposition of PLGA, and the protection of inert gas inhibits the pre - corrosion of the magnesium matrix in a humid environment, ensuring the chemical stability of the coating / matrix interface.

[0041] In the present invention, in step S3, the width of the strip is 1.5 - 6.0 mm, and the diameter of the magnesium alloy wire is 0.8 - 4.0 mm. The present invention does not impose special restrictions on the number of cold drawing times, as long as the magnesium alloy wire of the set size can be formed.

[0042] In the present invention, liquid paraffin is sprayed as a lubricant during the cold drawing process to reduce the friction coefficient between the drawing die and the magnesium wire, prevent surface scratches (scratches will become the starting point of corrosion), and at the same time avoid overheating of the magnesium wire due to plastic deformation (the cold working temperature < 100 °C).

[0043] In the present invention, after the cold drawing step, it further includes a step of low - temperature plasma sterilization. Further, in the low - temperature plasma sterilization, the sterilization power is 200 - 300 W, the temperature is 30 - 40 °C, and the time is 20 - 40 min. Low - temperature sterilization avoids causing softening of PLGA or oxidation of the magnesium wire; the active particles of the plasma kill microorganisms through free - radical reactions and do not leave toxic substances.

[0044] In the present invention, the parameters of the friction stir additive manufacturing technology are as follows: the rotational speed of the stirring head is 200 - 3000 rpm, the traveling speed is 12 - 300 mm / min; the deposition layer spacing is 0.5 - 3.0 mm, and the axial pressure is 2 - 15 kN, so as to control the input of frictional heat, make the magnesium wire undergo plastic flow but not exceed the solidus temperature, and avoid grain coarsening.

[0045] After the additive layer is obtained by layer-by-layer deposition using the friction stir additive manufacturing technology in the present invention, it further includes the step of separating the magnesium alloy substrate and the additive layer, and then the additive layer is precisely machined by numerical control machining (CNC) according to clinical requirements. It is necessary to ensure the machining accuracy, with the dimensional tolerance ≤ ±0.05 mm and the surface roughness ≤ 2 μm. The thickness of the additive layer in the present invention is not particularly limited and can be selected according to actual needs. Preferably, it is 0.8 - 1.5 mm in the present invention.

[0046] The present invention also provides a highly corrosion-resistant biodegradable magnesium-based composite material prepared by the above preparation method.

[0047] The technical solution of the present invention will be further elaborated below in conjunction with specific embodiments. The present invention has no special restrictions on the sources of the reagents used in the following embodiments, and commercially available products well-known to those skilled in the art can be used. In the following embodiments, the molar ratio of polylactic acid to glycolic acid in PLGA is 75:25. In the following embodiments, the particle size of Y2O3 is 30 - 60 nm, the particle size of HA (hydroxyapatite) is 20 - 80 nm, and the particle size of ZrO2 is 40 - 75 nm.

[0048] Example 1

[0049] This example provides a solid-phase additive preparation method for a highly corrosion-resistant biodegradable magnesium-based composite material.

[0050] The substrate and foil used in this example are AZ91 magnesium alloy. The size of the substrate is 200 mm * 40 mm * 5 mm, the width of the foil is 15 mm, and the thickness is 0.1 mm. The reinforcing phases used are Y2O3 and HA. The thickness of a single additive layer is 1 mm. The diameter of the shoulder used is 20 mm. The additive component is a cuboid component of 150 mm * 20 mm * 20 mm. The specific method includes the following steps:

[0051] (1) Add 2.5 g of Y2O3, 2.5 g of HA and 40 g of PLGA into 200 mL of acetone, ultrasonically disperse (300 W, 40 kHz, 30 min), then mechanically stir (1000 rpm, 30 min), and degas under vacuum for 30 min to obtain a uniform composite slurry.

[0052] (2) Vertically immerse the magnesium foil that has been ultrasonically cleaned with acetone, pickling-activated (5% HNO3, 30 s), washed with water and dried into the composite slurry at a lifting speed of 10 mm / s and a residence time of 45 s. Then dry it at 50 °C for 1 h under Ar gas protection. The coating thickness is about 15 μm.

[0053] (3) Cut the coated magnesium foil into 1.5-mm-wide strips and draw them into 1.0-mm-diameter wire through 5 passes of cold drawing, spraying liquid paraffin for lubrication during drawing. Then sterilize it by low-temperature plasma with a power of 200 W, a temperature of 40 °C, and a time of 30 min.

[0054] (4) Set the rotational speed of the friction stir additive manufacturing device to 1000 rpm, the traveling speed to 80 mm / min, and the axial pressure to 5 kN. Start the device and perform additive manufacturing according to the set program.

[0055] (5) After the additive manufacturing is completed, wait for the component to cool to room temperature and then take it out. Use wire cutting to separate the substrate and the additive layer, and then machine it into a rectangular component with a milling machine.

[0056] Figure 2 The microstructural picture of the highly corrosion-resistant biodegradable magnesium-based composite material prepared in this example is shown. It can be seen that the reinforcing phase is evenly mixed with the magnesium alloy matrix, and the forming is good without defects. Figure 3 It is the scanning picture of the reinforcing particles of the highly corrosion-resistant biodegradable magnesium-based composite material prepared in this example. It can be seen that the reinforcing phase is evenly distributed in the magnesium alloy matrix without obvious agglomeration phenomenon.

[0057] Example 2

[0058] This example provides a solid-phase additive manufacturing method for a highly corrosion-resistant biodegradable magnesium-based composite material.

[0059] The substrate and foil used are AZ91 magnesium alloy. The substrate size is 200 mm * 40 mm * 5 mm, the foil width is 15 mm, and the thickness is 0.1 mm. The reinforcing phases used are Y2O3 and ZrO2. The thickness of a single additive layer is 1 mm. The diameter of the shoulder used is 20 mm. The additive component is a rectangular component of 150 * 20 * 20 mm 3 Specific methods include the following steps:

[0060] (1) Add 2.5 g of Y2O3, 2.5 g of ZrO2 and 40 g of PLGA into 200 mL of acetone. After ultrasonic dispersion (300 W, 40 kHz, 30 min), mechanically stir (1000 rpm, 30 min), and perform vacuum degassing for 30 min to obtain a uniform slurry;

[0061] (2) Vertically immerse the magnesium foil that has been ultrasonically cleaned with acetone, pickling-activated (5% HNO3, 30 s), washed with water and dried into the slurry at a pulling speed of 10 mm / s and a residence time of 45 s. Then dry it at 50 °C for 1 h under Ar gas protection, and the coating thickness is 15 μm;

[0062] (3) Cut the coated magnesium foil into 1.5-mm-wide strips and draw them into 1.0-mm-diameter wire through 5 passes of cold drawing, spraying liquid paraffin for lubrication during drawing. Then sterilize it by low-temperature plasma with a power of 200 W, a temperature of 40 °C, and a time of 30 min;

[0063] (4) Set the rotational speed of the friction stir additive manufacturing device to 1000 rpm, the traveling speed to 80 mm / min, and the axial pressure to 5 kN. Start the device and perform additive manufacturing according to the set program;

[0064] (5) After the additive manufacturing is completed, wait for the component to cool to room temperature and then take it out. Use wire cutting to separate the substrate and the additive layer, and then machine it into a rectangular component with a milling machine.

[0065] Figure 4 This is the microstructure picture of the high-corrosion-resistant biomedical degradable magnesium-based composite material prepared in this example. It can be seen that the reinforcing phase and the magnesium alloy matrix are evenly mixed, and there are microvoids in some parts of the magnesium-based composite material. Figure 5 This is the scanning picture of the reinforcing particles of the high-corrosion-resistant biomedical degradable magnesium-based composite material prepared in this example. It can be seen that the reinforcing phase is relatively evenly distributed in the magnesium alloy matrix, and there is an agglomeration phenomenon of nano-reinforcing phase in some areas.

[0066] Example 3

[0067] This example provides a solid-phase additive manufacturing method for a high-corrosion-resistant biomedical degradable magnesium-based composite material.

[0068] The substrate and foil used in this example are AZ31 magnesium alloy. The substrate size is 200 mm * 40 mm * 5 mm, the foil width is 15 mm, and the thickness is 0.3 mm. The reinforcing phases used are HA and ZrO2. The thickness of a single additive layer is 1 mm. The diameter of the shoulder used is 20 mm. The additive component is a 150 mm * 20 mm * 20 mm rectangular component. The specific method includes the following steps:

[0069] (1) Add 2.5 g of HA, 2.5 g of ZrO2 and 40 g of PLGA to 200 mL of acetone, ultrasonically disperse (300 W, 40 kHz, 30 min), then mechanically stir (1000 rpm, 30 min), and degas under vacuum for 30 min to obtain a uniform slurry;

[0070] (2) Vertically immerse the magnesium foil that has been ultrasonically cleaned with acetone, pickling-activated (5% HNO3, 30 s), washed with water and dried into the slurry at a pulling speed of 10 mm / s and a residence time of 45 s. Then dry it at 50 °C for 1 h under Ar gas protection, and the coating thickness is 15 μm;

[0071] (3) Cut the coated magnesium foil into 1.5-mm-wide strips and draw them into 1.0-mm-diameter wire through 5 passes of cold drawing, and spray liquid paraffin for lubrication during drawing. Then carry out low-temperature plasma sterilization with a power of 200 W, a temperature of 40 °C, and a time of 30 min;

[0072] (4) Set the rotational speed of the friction stir additive manufacturing device to 1000 rpm, the traveling speed to 80 mm / min, and the axial pressure to 5 kN. Start the device and carry out additive manufacturing according to the set program;

[0073] (5) After the additive manufacturing is completed, wait for the component to cool to room temperature and then take it out. Separate the substrate and the additive layer by wire cutting, and then machine it into a rectangular component with a milling machine.

[0074] Example 4

[0075] This example provides a solid-phase additive manufacturing method for a highly corrosion-resistant biodegradable magnesium-based composite material for biomedical use.

[0076] The substrate and foil used in this example are WE43 magnesium alloy. The substrate size is 200 mm * 40 mm * 5 mm, the width of the foil is 12 mm, and the thickness is 0.5 mm. The reinforcing phases used are HA and ZrO2. The thickness of a single additive layer is 1.8 mm. The diameter of the shoulder used is 20 mm. The additive component is a rectangular component of 150 * 20 * 20 mm 3 . The specific method includes the following steps:

[0077] (1) Add 2.5 g of HA, 2.5 g of ZrO2 and 30 g of PLGA to 100 mL of acetone, ultrasonically disperse (300 W, 40 kHz, 30 min), then mechanically stir (300 rpm, 30 min), and carry out vacuum degassing for 30 min to obtain a uniform slurry;

[0078] (2) Vertically immerse the magnesium foil that has been ultrasonically cleaned with acetone, pickling-activated (5% HNO3, 30 s), washed with water and dried into the slurry at a pulling speed of 10 mm / s and a residence time of 45 s. Then dry it at 50 °C for 1 h under Ar gas protection, and the coating thickness is 15 μm;

[0079] (3) Cut the coated magnesium foil into 1.5-mm-wide strips and draw them into 1.5-mm-diameter wire through 5 passes of cold drawing, and spray liquid paraffin for lubrication during drawing. Then carry out low-temperature plasma sterilization with a power of 200 W, a temperature of 40 °C, and a time of 30 min;

[0080] (4) Set the rotational speed of the friction stir additive manufacturing device to 1000 rpm, the travel speed to 80 mm / min, and the axial pressure to 5 kN. Start the device and perform additive manufacturing according to the set program;

[0081] (5) After the additive manufacturing is completed, wait for the component to cool to room temperature and then take it out. Use wire cutting to separate the substrate and the additive layer, and then use a milling machine to process it into a rectangular component.

[0082] Example 5

[0083] This example provides a solid-phase additive manufacturing method for a highly corrosion-resistant biodegradable magnesium-based composite material for biomedical use.

[0084] The substrate and foil used in this example are ZK61 magnesium alloy. The size of the substrate is 150*60*3 mm 3 , the width of the magnesium foil is 16 mm, and the thickness is 0.3 mm. The reinforcing phases used are Y2O3, HA, and ZrO2. The thickness of a single additive layer is 2.1 mm. The diameter of the shoulder used is 28 mm. The additive component is a rectangular component of 120*28*40 mm 3 . The specific method includes the following steps:

[0085] (1) Add 5 g of Y2O3, 2.5 g of HA, 2.5 g of ZrO2, and 50 g of PLGA to 150 mL of acetone. After ultrasonic dispersion (200 W, 20 kHz, 25 min), perform mechanical stirring (200 rpm, 50 min), and vacuum degas for 40 min to obtain a uniform slurry;

[0086] (2) Vertically immerse the magnesium foil that has been ultrasonically cleaned with acetone, pickled and activated (5% HNO3, 60 s), washed with water and dried in the slurry. The lifting speed is 10 mm / s, the residence time is 25 s, and then dry it at 50 °C for 1 h under Ar gas protection to obtain a uniform coating;

[0087] (3) Cut the coated magnesium foil into 2.5-mm-wide strips, and make wires with a diameter of 2.0 mm through 5 passes of cold drawing. Spray liquid paraffin for lubrication during drawing. Then perform low-temperature plasma sterilization, with a power of 300 W, a temperature of 60 °C, and a time of 30 min;

[0088] (4) Set the rotational speed of the friction stir additive manufacturing device to 500 rpm, the travel speed to 150 mm / min, and the axial pressure to 7.5 kN. Start the device and perform additive manufacturing according to the set program;

[0089] (5) After the additive manufacturing is completed, wait for the component to cool to room temperature and then take it out. Use wire cutting to separate the substrate and the additive layer, and then use a milling machine to process it into a rectangular component.

[0090] Comparative Example 1

[0091] Compared with Example 1, this comparative example is different in that this comparative example does not contain PLGA, as well as Y2O3 and HA nano-reinforcing phases.

[0092] Comparative Example 2

[0093] Compared with Example 2, this comparative example is different in that Y2O3 and ZrO2 nano-reinforcing phases are not added to the materials of this comparative example.

[0094] Comparative Example 3

[0095] Compared with Example 3, this comparative example is different in that no coating and reinforcing nanoparticles are coated on the surface of the magnesium foil. The specific preparation method is as follows:

[0096] (1) Cut the magnesium foil that has been ultrasonically cleaned with acetone and pickling-activated (5% HNO3, 30 s) into 1.5 mm wide strips, and cold-draw it into a wire with a diameter of 1.0 mm through 5 passes. Liquid paraffin is sprayed for lubrication during drawing. Then it is subjected to low-temperature plasma sterilization with a power of 200 W, a temperature of 40 °C, and a time of 30 min;

[0097] (2) Set the rotational speed of the friction stir additive manufacturing device to 1000 rpm, the traveling speed to 80 mm / min, and the axial pressure to 5 kN. Start the device and add materials according to the set program;

[0098] (3) After the additive manufacturing is completed, wait for the component to cool to room temperature and then take it out. Separate the substrate and the additive layer by wire cutting, and then machine it into a rectangular component with a milling machine.

[0099] Comparative Example 4

[0100] This comparative example prepares a biodegradable magnesium-based composite material for biomedical use by the method of traditional casting magnesium alloy. The specific steps are as follows:

[0101] S1 Vacuum melt the WE43 magnesium alloy at 650 °C for 30 minutes, add 3 wt% of HA and ZrO2 (mass ratio 1:1) and carry out mechanical stirring;

[0102] S2 Pour the magnesium-based composite material into a mold, cool and solidify it, and carry out homogenization annealing treatment at 420 °C for 18 hours, and then extrude it into shape;

[0103] S3 Carry out T6 post-heat treatment (solution treatment at 425 °C for 8 hours + artificial aging at 225 °C for 16 hours) on the above magnesium-based composite material, and cut it into the required components.

[0104] Test Example

[0105] 1. Determination of mechanical properties

[0106] The tensile strength of the biodegradable magnesium-based composite materials of Examples 1-5 and Comparative Examples 1-4 was tested using a universal tensile testing machine, as shown in Table 1.

[0107] Table 1 Tensile strength data of the biodegradable magnesium-based composite materials for biomedical applications

[0108] Number Tensile Strength (MPa) Number Tensile Strength (MPa) Example 1 265.6 Comparative Example 1 215.6 Example 2 273.8 Comparative Example 2 206.9 Example 3 335.6 Comparative Example 3 286.5 Example 4 312.1 Comparative Example 4 256.5 Example 5 326.8

[0109] It can be seen from the comparative implementation examples that compared with the preparation of magnesium-based composite materials by traditional methods, the mechanical properties of the magnesium alloys prepared by the present invention are more excellent, the distribution of their reinforcing particles is more uniform, and the agglomeration phenomenon is not obvious.

[0110] 2. Determination of corrosion resistance

[0111] After the prepared magnesium-based composite materials were polished and ultrasonically cleaned, they were dried. Subsequently, they were placed in a sterile simulated body fluid for corrosion tests. After the set corrosion time, the corrosion specimens were taken out and dried and weighed at 60 °C for 24 hours to analyze the corrosion weight loss of the materials (the corrosion weight loss of typical Comparative Example 15 days is shown in Table 2), and the corrosion specimens were observed by SEM electron microscopy. Figure 6 and Figure 7 are the corrosion morphology diagrams of the highly corrosion-resistant biodegradable magnesium-based composite materials prepared in Example 1 and Example 2 after 15 days of corrosion in sterile simulated body fluid. It can be seen that the corrosion pits in Example 1 are small and uniform, and there are many pitting corrosion pits and fibrous corrosion on the surface; the corrosion pits in Example 2 are deeper, and there are relatively obvious microbial pitting corrosion pits.

[0112] Table 1 Comparison of corrosion data of the biodegradable magnesium-based composite materials for biomedical applications (corrosion in simulated body fluid for 15 days)

[0113] Number <![CDATA[Corrosion weight loss (mg / mm 3 )]]> Number <![CDATA[Corrosion weight loss (mg / mm 3 )]]> Example 1 0.053 Comparative Example 1 0.193 Example 2 0.046 Comparative Example 2 0.201 Example 3 0.031 Comparative Example 3 0.186

[0114] It can be seen from Table 1 that after 15 days of corrosion in simulated body fluid, the corrosion weight loss of the magnesium-based composite materials prepared by the method of the examples of the present invention is significantly lower than that of the corresponding comparative examples, confirming that the magnesium-based composite materials prepared by the examples of the present invention have better corrosion resistance.

[0115] 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 can have various changes and modifications. 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 solid-phase additive manufacturing method for a highly corrosion-resistant biodegradable magnesium-based composite material, characterized in that, It includes the following steps: S1. Dissolve the nano-reinforcement phase and poly(lactic-co-glycolic acid) in a solvent, ultrasonically disperse and then stir to form a uniform suspension, and defoam to obtain a composite slurry; S2. Vertically immerse the magnesium alloy foil into the composite slurry, lift it multiple times and then dry it to form a magnesium alloy foil coated with a composite layer; S3. Cut the magnesium alloy foil coated with the composite coating into strips, and manufacture magnesium alloy wires through multiple cold drawing processes; S4. Using the magnesium alloy wire as a raw material, layer-by-layer deposit on a magnesium alloy substrate by wire-filled friction stir additive manufacturing technology to obtain the highly corrosion-resistant biodegradable magnesium-based composite material.

2. The solid-phase additive manufacturing method according to claim 1, wherein The nano-reinforcement phase is selected from one or more of hydroxyapatite, Y2O3, ZrO2, CaO, SiC or TiC; the particle size of the nano-reinforcement phase is 20 - 500 nm.

3. The solid-phase additive manufacturing method according to claim 1, wherein In the poly(lactic-co-glycolic acid), the molar ratio of polylactic acid to glycolic acid is (70 - 85):(15 - 30); in step S1, the dosage ratio of the nano-reinforcement phase, poly(lactic-co-glycolic acid) and the solvent is 1 g:(5 - 10) g:(30 - 80) mL; the solvent is selected from one or more of acetone, tetrahydrofuran or ethyl acetate.

4. The solid-phase additive manufacturing method according to claim 1, wherein The time of ultrasonic dispersion is 10 - 60 min, and the power of ultrasonic is 100 - 800 W; the rotation speed of stirring is 50 - 800 rpm, and the time of stirring is 10 - 60 min.

5. The solid-phase additive manufacturing method according to claim 1, wherein In step S2, before the magnesium alloy foil is vertically immersed into the composite slurry, it also includes a step of pre-treating the magnesium alloy foil, and the pre-treatment includes cleaning with acetone, nitric acid and water in sequence, and drying to obtain.

6. The solid-phase additive manufacturing method according to claim 1, wherein, In step S2, the thickness of the magnesium alloy foil is 0.1 - 2.0 mm; the drying is carried out at 40 - 60 °C under the protection of inert gas; in the magnesium alloy foil coated with the composite layer, the thickness of the composite layer is 5 - 30 μm.

7. The solid-phase additive manufacturing method according to claim 1, wherein In step S3, the width of the strip is 1.5 - 6.0 mm, and the diameter of the magnesium alloy wire is 0.8 - 4.0 mm.

8. The solid-phase additive manufacturing method according to claim 1, wherein, Liquid paraffin is sprayed as a lubricant during the cold drawing process; after the cold drawing step, it also includes a step of low-temperature plasma sterilization.

9. The solid-phase additive manufacturing method according to claim 1, wherein, The parameters of the friction stir additive manufacturing technology are as follows: the rotation speed of the stirring head is 200 - 3000 rpm, the traveling speed is 12 - 300 mm / min; the deposition layer spacing is 0.5 - 3.0 mm, and the axial pressure is 2 - 15 kN.

10. A highly corrosion-resistant biodegradable magnesium-based composite material prepared by the solid-phase additive preparation method according to any one of claims 1 - 9.

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