Medical 3D printing shape memory composite reinforced material and preparation method

Abstract

The application discloses a kind of medical 3D printing shape memory composite reinforcing materials and preparation method, the present application will be mixed after nano-state prussian blue analogue, dispersing agent and surfactant ultrasonic oscillation dispersion prussian blue analogue nano-suspension, medical shape memory alloy powder is added to suspension and is carried out electromagnetic stirring mixing and constant temperature electrostatic assembly, sequentially filter solvent, dry and screen treatment after preparation medical 3D printing shape memory composite powder, and based on the composite powder laser in situ synthesis obtains medical shape memory composite reinforcing material.The present application is highly dispersed by electrostatic assembly shape memory alloy micro powder and prussian blue analogue mixed together;When laser 3D printing is shaped, prussian blue analogue and shape memory alloy are reacted to form meso-entropy nano-alloy precipitated phase, TiN and TiC composite ceramic reinforcement, improve the biocompatibility, tribology and fatigue mechanical properties of shape memory alloy, prolong the service cycle of product.

Description

Technical Field

[0001] This invention belongs to the field of materials and relates to a laser 3D printing material preparation technology, specifically to a medical 3D printing shape memory composite reinforcement material and its preparation method. Background Technology

[0002] Shape memory alloys are considered one of the most promising medical smart materials in the field of engineering technology, exhibiting superior functional properties that traditional metal materials cannot possess. For example, they exhibit superelasticity and shape memory effects, characterized by the complete recovery of plastic strain after stress unloading and the automatic return to the initial shape before deformation after heating. Furthermore, shape memory alloys possess superior thermomechanical stability and corrosion resistance, outperforming widely used clinical stainless steel materials. Their biocompatibility, high elastic damping capacity, and low Young's modulus effectively meet clinical needs, making them valuable for in-depth applications in the medical field. Surgical implants made from medical shape memory alloys, such as orthodontic expanders, jaw fixation pins, venous valve supports, cardiac occluders, zygomatic fixators, and artificial cardiovascular stent grafts, have been actively used in clinical interventional treatments. However, when long-term or even permanent implantation is required, their limited biotribological and fatigue mechanical properties can easily lead to local inflammation and prosthesis loosening in the surrounding tissues, resulting in a shortened service life and a significant increase in production and usage costs for surgical implants and clinical medical devices.

[0003] Currently, the geometric design and functional requirements of medical shape memory alloy implants are becoming increasingly diversified. Generally, they must be customized according to each patient's individual characteristics and treatment plan. Traditional hot-working processes such as forging and casting, followed by milling and machining, inevitably result in disadvantages such as low material utilization, long production cycles, and extremely high manufacturing costs. Laser 3D printing technology can transform the complex three-dimensional structure of medical implants through geometric modeling and layer-by-layer slicing into rapid, layer-by-layer stacking within a two-dimensional plane. This offers extremely high flexibility for personalized customization, shortens a series of mold-making and machining post-processing steps, and enables the rapid, integrated manufacturing of high-precision clinical medical devices integrating materials, structure, and forming. Furthermore, the effective recycling of raw material powder can further reduce the medical costs and production cycles required for personalized patient customization.

[0004] When medical shape memory alloys are modified by introducing nano-state Prussian blue analogues, the excellent tribological properties and non-allergenic detoxification properties of Prussian blue analogues can improve the medical implantability of medical shape memory alloys, preventing premature failure in patients due to short service life. Currently, there is a gap in the technology for laser 3D printing of Prussian blue analogue-modified medical shape memory composite reinforcement materials and their preparation methods. Furthermore, the common technical principle in preparing composite reinforcement materials is to mechanically combine the reinforcement with the alloy matrix to form a powder mixture, which is then laser 3D printed. Medical composite reinforcement materials prepared by the above methods generally suffer from metallurgical defects such as stress concentration and interface cracks caused by interfacial structural mismatch and uneven dispersion during laser 3D printing, which has extremely limited effect on improving the overall performance of medical shape memory composite materials. Summary of the Invention

[0005] This invention addresses the problems of existing medical shape memory composite reinforcement materials, such as low interfacial bonding strength, limited reinforcement types, significant agglomeration effects, and susceptibility to structural damage and reduced sphericity during preparation, as well as the existing problems in the preparation of medical shape memory alloys using laser 3D printing. It provides a method for preparing medical 3D printed shape memory composite reinforcement materials. This invention involves pre-preparing nano-state Prussian blue analogues through chemical synthesis, then adding dispersants and surfactants for ultrasonic dispersion to create a Prussian blue analogue nano-suspension (the surfactants cause the Prussian blue analogue surface to carry a negative charge). Medical shape memory alloy powder is added to a suspension. The medical shape memory alloy powder, carrying a positive charge on its surface, is dispersed in the suspension. During electromagnetic stirring and mixing, electrostatic assembly (isothermal electrostatic assembly) occurs through the positive and negative charge effect, resulting in a high degree of dispersion of the medical shape memory alloy powder and Prussian blue analogue. This avoids the agglomeration, structural damage, and decreased sphericity of the alloy powder caused by mechanical ball milling in existing technologies. After solvent removal, drying, and sieving, a medical 3D printing shape memory composite powder is obtained. Based on this composite powder, a composite reinforcing material is synthesized in situ using laser technology. The powder material prepared by this invention, with functional group-activated modified Prussian blue analogue nanocubes, can form a stable electrostatic assembly effect with the shape memory alloy micropowder. During laser 3D printing, the Prussian blue analogue reacts with the shape memory alloy to form a medium-entropy nano-alloy precipitate phase and a TiN and TiC composite ceramic reinforcement. This allows the composite reinforcing material to possess excellent biocompatibility, tribological, and fatigue mechanical properties, extending its service life as a medical implant.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a medical 3D printing shape memory composite reinforcement material, the specific steps of which are as follows:

[0008] (1) Prepare nano-state Prussian blue analog powder;

[0009] (2) After mixing surfactant, dispersant and nano-state Prussian blue analog powder, ultrasonic vibration is used to make the treatment uniformly dispersed and activate functional groups to prepare Prussian blue analog nano suspension. The surfactant makes the surface of Prussian blue analog in the suspension carry negative charge.

[0010] (3) Prepare medical shape memory alloy powder, add medical shape memory alloy powder to Prussian blue analog nano suspension, mix by electromagnetic stirring and electrostatic assembly at constant temperature, and obtain medical 3D printing shape memory composite powder after solvent removal, drying and sieving treatment in sequence.

[0011] Preferably, in step (1), the preparation method of the nano-state Prussian blue analog powder is as follows:

[0012] Transition metal salts were added to a hydride inorganic ligand solution and aged at a constant temperature under stirring conditions to carry out chemical precipitation.

[0013] After generating the corresponding product, the supernatant was removed by multiple centrifugation and washing until no reactants remained in the supernatant. After drying, nano-sized Prussian blue analog powder was obtained.

[0014] Preferably, in step (1), the transition metal salt is any one or more of nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride hexahydrate; the inorganic ligand solution is a mixed aqueous solution of potassium hexacyanoferrate-polyvinylpyrrolidone-trisodium citrate dihydrate.

[0015] Further preferably, the nano-state Prussian blue analogue is a cubic particle with a particle size of 50–120 nm.

[0016] Further preferably, the concentrations of nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride hexahydrate are not less than 99.9%, and the preparation ratio of the mixed aqueous solution of potassium hexacyanoferrate-polyvinylpyrrolidone-trisodium citrate dihydrate is 2.7g:4g:2.5g:200mL to 3.0g:4.5g:2.8g:200mL, with the concentrations of potassium hexacyanoferrate, polyvinylpyrrolidone, and trisodium citrate dihydrate not less than 99.5%.

[0017] Preferably, in step (1), the constant temperature aging temperature is 25-50℃, and the chemical precipitation time is 18-24h;

[0018] Preferably, in step (1), the duration of each centrifugation treatment is 20 to 35 minutes, and the centrifugation speed is 8000 to 12000 r / min;

[0019] Preferably, in step (1), the drying temperature is 60-80°C and the overnight time is 12-16 hours.

[0020] Preferably, in step (2), the surfactant is any one or more of polyethylene glycol, dodecylbenzenesulfonic acid, dodecyl dimethylamine oxide and sodium hexadecyl sulfate; the dispersant is any one or more of methylpyrrolidone, ammonium polyacrylate, hexadecyltrimethylammonium bromide and sodium dodecylbenzenesulfonate.

[0021] When the dispersant is a solid powder such as hexadecyltrimethylammonium bromide and sodium dodecylbenzenesulfonate, an alcohol solvent such as ethanol should also be added.

[0022] More preferably, the formulation ratio of surfactant, dispersant and nano-state Prussian blue analog is 20mL:100mL:1g to 40mL:150mL:1g, the concentration of polyethylene glycol, dodecylbenzenesulfonic acid, dodecyl dimethylamine oxide and sodium hexadecyl sulfate solution is not less than 99%, and the concentration of methylpyrrolidone, ammonium polyacrylate, hexadecyl trimethylammonium bromide and sodium dodecylbenzenesulfonate solution is not less than 90%.

[0023] Preferably, in step (2), the ultrasonic oscillation time is 1 to 2 hours.

[0024] Preferably, in step (2), the ultrasonic oscillation dispersion process is carried out in an experimental high-frequency ultrasonic cleaner, with an ultrasonic oscillation output power of 300-400W and a fixed frequency of 40kHz.

[0025] Preferably, in step (3), the medical shape memory alloy powder is a spherical powder with a particle size of 15-105 μm, wherein the powder particle size suitable for selective laser melting process is 15-53 μm, and the powder particle size suitable for laser near-net-shape forming process is 53-105 μm;

[0026] Preferably, the mass fraction of nano-Prussian blue analogue in the medical 3D printing shape memory composite powder is 1.0%–5.0%.

[0027] More preferably, both the medical shape memory composite powder and the prepared medical 3D printing shape memory composite reinforcing material conform to the ASTM F 2063-18 standard, "Ni-TiO2 Shape Memory Alloy Processed Materials for Medical Devices and Surgical Implants".

[0028] Preferably, by mass percentage, the medical shape memory alloy powder contains 52.5-58.5% Ni, ≤0.03% Fe, ≤0.05% C, ≤0.01% Co, ≤0.02% Cu, ≤0.02% Nb, ≤0.01% Cr, ≤0.002% H, ≤0.005% N, ≤0.01% O, with the balance being Ti.

[0029] Preferably, in step (3), the electromagnetic stirring mixing time is 30-60 min, the constant temperature electrostatic assembly temperature is 45-65℃, and the constant temperature electrostatic assembly time is 60-90 min.

[0030] Preferably, in the filtration, drying and sieving process of step (3), the solvent filtration process is carried out in a vacuum filtration device, the vacuum drying temperature is 80-120℃, and the vacuum drying time is 6-8h; the sieving preferably uses composite powder with a particle size range of 15-105μm and a highly spherical surface.

[0031] This invention is based on the high-temperature self-propagating in-situ chemical reaction between functional group-activated modified nano-Prussian blue analogues and medical shape memory alloys. Utilizing the interaction between a high-energy-density laser beam and the powder material system, a high-temperature self-propagating in-situ chemical reaction is induced in the composite powder material during laser 3D printing to synthesize a medium-entropy nano-alloy precipitate phase and a TiN / TiC composite ceramic reinforcement. This allows for the preparation of a shape-and-property synergistically controlled medical shape memory composite reinforcement material, thereby regulating the biocompatibility, tribological properties, and fatigue mechanical properties of the composite reinforcement material. The relevant high-temperature self-propagating in-situ chemical reaction equation is as follows:

[0032]

[0033] The preparation principle of medical 3D printed shape memory composite reinforcement material: A surfactant is used to activate the functional groups on the surface of controllably synthesized nano-state Prussian blue analogues, exciting the covalent hydrogen atoms in chemical functional groups such as amino, carboxyl, and hydroxyl groups to form negative charges. This generates the electrostatic repulsion force required to maintain the stable dispersion of the Prussian blue analogues, further weakening the van der Waals attraction. This results in uniform dispersion and electrostatic assembly on the surface of medical shape memory alloy micropowder, producing a medical modified composite powder. Subsequently, under laser 3D printing induction, a medium-entropy nano-alloy precipitate phase and a TiN / TiC composite ceramic reinforcement phase are synthesized in situ through self-propagation.

[0034] The beneficial effects of this invention are:

[0035] (1) In the preparation process of the medical 3D printing shape memory composite reinforcement material of the present invention, the surfactant treats the free amino, carboxyl and hydroxyl groups of the negatively charged nano-state Prussian blue analogue on the surface, which can form a stable electrostatic assembly effect on the surface of the positively charged shape memory alloy micro powder. The Prussian blue analogue nanocubes are uniformly dispersed and electrostatically adsorbed on the surface of the shape memory alloy micro powder, which effectively avoids the dense agglomeration, structural damage and reduction of alloy powder sphericity caused by mechanical ball milling and mixing. At the same time, it has excellent assembly stability and laser printing performance.

[0036] (2) In the medical 3D printing shape memory composite powder of the present invention, the Prussian blue analog nanomaterial has extremely high laser absorption efficiency, and the uneven cubic surface features can effectively hinder the multiple reflections, absorption and escape of the laser beam, effectively improve the laser heat input efficiency of the medical shape memory alloy material system, and help improve the forming quality of 3D printing.

[0037] (3) This invention uses medical 3D printing shape memory composite powder laser printing to prepare medical shape memory composite reinforcement materials. During laser 3D printing, nano-Prussian blue analogues and shape memory alloys are synthesized in situ at high temperature through high-entropy nano-alloy precipitates and TiN and TiC composite ceramic reinforcements. This is beneficial for the composite reinforcement materials to have excellent biocompatibility, tribological and fatigue mechanical properties, which can extend the service life of medical artificial implants. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating the fabrication process of shape memory composite reinforcement materials for medical 3D printing.

[0039] Figure 2 The image shows the surface morphology of the medical 3D printing shape memory composite powder used in Example 1. Figure 2 Image A is a low-magnification surface morphology image of shape memory composite powder for medical 3D printing. Figure 2 Image B is a high-magnification image of the surface morphology of shape memory composite powder used in medical 3D printing;

[0040] Figure 3 The image shows the microstructure of the shape memory composite reinforced material prepared from medical 3D printing shape memory composite powder in Example 1. Figure 3 Image A is a low-magnification micrograph of the shape memory composite reinforced material. Figure 3 Image B is a high-magnification micrograph of the shape memory composite reinforced material;

[0041] Figure 4 This is a comparison chart of the friction and wear test results of the shape memory composite reinforced material prepared from the medical 3D printing shape memory composite powder in Example 1 and the original alloy material. Figure 4Figure A shows a comparison of the friction coefficients between the shape memory composite reinforced material and the original alloy material. Figure 4 Image B shows a comparison of the wear mark depth between the shape memory composite reinforced material and the original alloy material. Figure 4 C represents the three-dimensional profile microstructure of the shape memory composite reinforced material and the original alloy material after friction and wear testing. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that several adjustments or improvements can be made without departing from the concept of the present invention, and these adjustments or improvements should still fall within the protection scope of the present invention.

[0043] Example 1: A method for preparing a medical 3D printed shape memory composite reinforcement material (see...) Figure 1 The specific steps are as follows:

[0044] (1) Preparation of nano-state Prussian blue analog powder: An inorganic ligand solution was prepared by mixing potassium hexahydrate and cobalt chloride hexahydrate metal salts with potassium hexacyanoferrate-polyvinylpyrrolidone-trisodium citrate dihydrate and deionized water in a ratio of 2.7g:4g:2.5g:200mL. The solution was then chemically precipitated by maintaining a constant temperature of 50℃ for 24 hours under continuous stirring. After aging, the solution was centrifuged for 30 minutes in a high-speed refrigerated centrifuge to remove the supernatant. The centrifugation speed was set to... After adding anhydrous ethanol at 9000 r / min, the reaction was repeated several times until no reactants remained in the supernatant. Then, the mixture was placed in a vacuum drying oven and dried overnight at 70℃ for 12 h. After collection, FeCoNi Prussian blue analog nanocube particles with a particle size of approximately 120 nm were obtained, which is the preparation of nano-state Prussian blue analog powder. The concentrations of nickel chloride hexahydrate and cobalt chloride hexahydrate were both 99.9%, and the concentrations of potassium ferric hexacyanate, polyvinylpyrrolidone, and trisodium citrate dihydrate were all 99.5%.

[0045] (2) The surfactant, dispersant and controllably synthesized nano-state Prussian blue analogue were prepared in a ratio of 20 mL: 100 mL: 1 g. The mixture was then subjected to ultrasonic oscillation for 2 h in an experimental high-frequency ultrasonic cleaner until it was uniformly dispersed and the functional groups were activated. The ultrasonic oscillation output power was 350 W and the fixed frequency was 40 kHz to obtain a Prussian blue analogue nano-suspension. The surfactant used was a 99% polyethylene glycol solution and the dispersant used was a 95% methylpyrrolidone solution.

[0046] (3) Medical shape memory alloy powder was added to a Prussian blue analog nano suspension and electromagnetically stirred for 60 min. Then, it was electrostatically assembled at 45°C for 90 min. After filtering out the solvent using a vacuum filtration device, it was dried in a vacuum drying oven at 120°C for 8 h. Powder particles with a preferred particle size range of 15–105 μm and a highly spherical surface were sieved to prepare medical 3D printing shape memory composite powder (hereinafter referred to as shape memory composite powder). The mass fraction of nano-Prussian blue analog in the medical 3D printing shape memory composite powder was 1.0%. The medical shape memory alloy powder was spherical with an average particle size of 45.5 μm, conforming to ASTM F 2063-18 "Ni-Titanium Shape Memory Alloy Processed Materials for Medical Devices and Surgical Implants". By mass percentage, the medical nickel-titanium alloy powder contained Ni 57.45%, Fe 0.02%, C 0.001%, Co 0.01%, Cu 0.008%, and Nb 0.02%. 0.015%, Cr 0.005%, H 0.002%, N 0.002%, O 0.008%, balance Ti;

[0047] The shape memory composite powder prepared in this embodiment contains 1.0% by mass of nano-Prussian blue analogue. The surface morphology of the shape memory composite powder is shown in [reference needed]. Figure 2 ,from Figure 2 It can be seen that the composite powder has no dense agglomeration, structural damage and reduced sphericity. Its surface is assembled with controllable synthesized nano-Prussian blue analogs with a particle size of about 120nm. After laser 3D printing, a medical shape memory composite reinforcement material containing a medium-entropy nano-alloy precipitate phase and a TiN and TiC composite ceramic reinforcement phase is synthesized in situ at high temperature through high temperature self-propagation.

[0048] The microstructure of the medical shape memory composite reinforcement material in this embodiment is shown in the figure. Figure 3 ,from Figure 3 It can be seen that under the action of high-energy laser, the composite powder generates in situ fine particulate FeCoNiTi medium-entropy nano-alloy precipitates and dendritic TiN and TiC composite ceramic reinforcing phases.

[0049] The tribological properties of the medical shape memory composite reinforced material in this embodiment are shown below. Figure 4 ,from Figure 4 It can be seen that the composite reinforced material prepared by laser 3D printing has a lower coefficient of friction and a shallower wear track depth compared with the original alloy material, thus exhibiting significantly improved tribological properties.

[0050] Example 2: A method for preparing a medical 3D printed shape memory composite reinforcement material (see Example 2) Figure 1 The specific steps are as follows:

[0051] (1) Preparation of nano-state Prussian blue analog powder: Add nickel chloride hexahydrate and manganese chloride hexahydrate metal salts to potassium hexacyanoferrate-polyvinylpyrrolidone-trisodium citrate dihydrate and deionized water in a ratio of 3.0g:4.5g:2.8g:200mL to prepare an inorganic ligand solution. Under continuous stirring, maintain a constant temperature of 25℃ for 18h for chemical precipitation treatment. After aging, centrifuge in a high-speed refrigerated centrifuge for 20min to remove the supernatant. The liquid was centrifuged at 12000 r / min, and anhydrous ethanol was added. The process was repeated several times until no reactants remained in the supernatant. Then, it was placed in a vacuum drying oven and dried overnight at 60℃ for 16 h. FeNiMn Prussian blue analog nanocube particles with a particle size of about 50 nm were obtained. The concentrations of nickel chloride hexahydrate and cobalt chloride hexahydrate were both 99.9%, and the concentrations of potassium ferric hexacyanate, polyvinylpyrrolidone, and trisodium citrate dihydrate were all 99.5%.

[0052] (2) The surfactant, dispersant and controllably synthesized nano-state Prussian blue analogue were prepared in a ratio of 40mL:150mL:1g. The mixture was then subjected to ultrasonic oscillation for 1 hour in an experimental high-frequency ultrasonic cleaner until it was uniformly dispersed and the functional groups were activated. The ultrasonic oscillation output power was 300W and the fixed frequency was 40kHz to obtain a Prussian blue analogue nano-suspension. The surfactant used was a 99% sodium hexadecyl sulfate solution and the dispersant used was a 90% hexadecyltrimethylammonium bromide solution.

[0053] (3) Medical shape memory alloy powder was added to a Prussian blue analog nano suspension and electromagnetically stirred for 30 min. Then, it was electrostatically assembled at 65°C for 60 min. After filtering out the solvent using a vacuum filtration device, it was dried in a vacuum drying oven at 80°C for 6 h. Powder particles with a particle size range of 15–105 μm and a highly spherical surface were selected by sieving to prepare medical 3D printing shape memory composite powder (hereinafter referred to as shape memory composite powder). The mass fraction of nano-Prussian blue analog in the medical 3D printing shape memory composite powder was 4.0%. The medical shape memory alloy powder was spherical with an average particle size of 85.9 μm, conforming to ASTM F 2063-18 "Ni-Titanium Shape Memory Alloy Processed Materials for Medical Devices and Surgical Implants". By mass percentage, the medical nickel-titanium alloy powder contained Ni 56.78%, Fe 0.03%, C 0.004%, Co 0.009%, Cu 0.01%, and Nb 0.00%. 0.015%, Cr 0.005%, H 0.001%, N 0.004%, O 0.009%, balance Ti;

[0054] The shape memory composite powder prepared in this embodiment contains 4.0% by mass of nano-Prussian blue analogue. The composite powder exhibits no dense agglomeration, structural damage, or reduction in sphericity. A medical shape memory composite reinforcement material containing FeMnNiTi medium-entropy nano-alloy precipitates and TiN and TiC composite ceramic reinforcement phases is synthesized in situ at high temperature via laser 3D printing.

[0055] Example 3: A method for preparing a medical 3D printed shape memory composite reinforcement material (see...) Figure 1 The specific steps are as follows:

[0056] (1) Preparation of nano-state Prussian blue analog powder: Add nickel chloride hexahydrate metal salt to potassium hexacyanoferrate-polyvinylpyrrolidone-trisodium citrate dihydrate and deionized water in a ratio of 2.8g:4.2g:2.6g:200mL to prepare an inorganic ligand solution. Under continuous stirring, maintain a constant temperature of 35℃ for 20h for chemical precipitation treatment. After aging, centrifuge in a high-speed refrigerated centrifuge for 30min to remove the supernatant. The centrifugation speed is set to 8000r / min. After adding anhydrous ethanol, repeat the process several times until there is no reactant residue in the supernatant. Then place it in a vacuum drying oven and dry at 70℃ overnight for 14h. After collection, FeNi Prussian blue analog nanocube particles with a particle size of about 105nm are obtained. The concentration of nickel chloride hexahydrate is 99.9%, and the concentrations of potassium hexacyanoferrate, polyvinylpyrrolidone and trisodium citrate dihydrate are all 99.5%.

[0057] (2) The surfactant, dispersant and controllably synthesized nano-state Prussian blue analogue were prepared in a ratio of 25 mL: 120 mL: 1 g. The mixture was then subjected to ultrasonic oscillation for 1.5 h in an experimental high-frequency ultrasonic cleaner until it was uniformly dispersed and the functional groups were activated. The ultrasonic oscillation output power was 400 W and the fixed frequency was 40 kHz to obtain a Prussian blue analogue nano-suspension. The surfactant used was a 99% dodecylbenzenesulfonic acid solution and the dispersant used was a 90% hexadecyltrimethylammonium bromide solution.

[0058] (3) Medical shape memory alloy powder was added to a Prussian blue analog nano suspension and electromagnetically stirred for 45 min. Then, it was electrostatically assembled at 50°C for 75 min. After filtering out the solvent using a vacuum filtration device, it was dried in a vacuum drying oven at 100°C for 7 h. Powder particles with a preferred particle size range of 15–105 μm and a highly spherical surface were sieved to prepare medical 3D printing shape memory composite powder (hereinafter referred to as shape memory composite powder). The mass fraction of nano-Prussian blue analog in the medical 3D printing shape memory composite powder was 3.0%. The medical shape memory alloy powder was spherical with an average particle size of 35.5 μm, conforming to ASTM F 2063-18 "Ni-TiO2 Shape Memory Alloy Processed Materials for Medical Devices and Surgical Implants". By mass percentage, the medical nickel-titanium alloy powder contained Ni 56.78%, Fe 0.03%, C 0.004%, Co 0.009%, Cu 0.01%, and Nb 0.00%. 0.015%, Cr 0.005%, H 0.001%, N 0.004%, O 0.009%, balance Ti;

[0059] The shape memory composite powder prepared in this embodiment contains 3.0% by mass of nano-Prussian blue analogue. The composite powder exhibits no dense agglomeration, structural damage, or reduction in sphericity. A medical shape memory composite reinforcement material containing FeNiTi medium-entropy nano-alloy precipitates and TiN and TiC composite ceramic reinforcement phases is synthesized in situ at high temperature through laser 3D printing.

[0060] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above. Those skilled in the art can make various adjustments or improvements within the scope of the claims, and all such adjustments or improvements should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a medical 3D printing shape memory composite reinforcement material, characterized in that, The specific steps are as follows: Prepare nano-state Prussian blue analogue powder; After mixing surfactant, dispersant and nano-state Prussian blue analog powder, ultrasonic oscillation was used to make the treatment uniformly dispersed and activate the functional groups to prepare a Prussian blue analog nano suspension. The surfactant made the surface of the Prussian blue analog in the suspension carry a negative charge. Medical shape memory alloy powder was prepared, and the medical shape memory alloy powder was added to a Prussian blue analog nano suspension. The mixture was electromagnetically stirred and electrostatically assembled at a constant temperature. After solvent removal, drying and sieving, medical 3D printing shape memory composite powder was obtained. Medical 3D printing shape memory composite powder is laser 3D printed. During laser 3D printing, nano-state Prussian blue analogue undergoes a high-temperature self-propagating in-situ chemical reaction with medical shape memory alloy to generate medium-entropy nano-alloy precipitates and TiN and TiC composite ceramic reinforcement, thus obtaining medical shape memory composite reinforcement material. The preparation method of the nano-state Prussian blue analog powder is as follows: A transition metal salt is added to an inorganic ligand solution and chemically precipitated by constant temperature aging under stirring conditions. The transition metal salt is any one or more of nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride hexahydrate. The inorganic ligand solution is a mixed aqueous solution of potassium hexacyanoferrate, polyvinylpyrrolidone, and trisodium citrate dihydrate. After generating the corresponding product, the supernatant was removed by multiple centrifugation and washing until no reactants remained in the supernatant. After drying, nano-sized Prussian blue analog powder was obtained.

2. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 1, characterized in that: The nano-state Prussian blue analogue is a cubic particle with a particle size of 50~120nm.

3. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 1, characterized in that: The constant temperature aging temperature is 25~50℃, and the chemical precipitation time is 18~24h.

4. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 1, characterized in that: Each centrifugation process lasted 20-35 minutes, and the centrifugation speed was 8000-12000 r / min.

5. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 1, characterized in that: The drying temperature is 60~80℃, and the drying time is 12~16h.

6. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 1, characterized in that: The surfactant is any one or more of polyethylene glycol, dodecylbenzenesulfonic acid, dodecyl dimethylamine oxide, and sodium hexadecyl sulfate; the dispersant is any one or more of methylpyrrolidone, ammonium polyacrylate, hexadecyltrimethylammonium bromide, and sodium dodecylbenzenesulfonate.

7. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 1, characterized in that: Medical-grade shape memory alloy powder is spherical powder with a particle size of 15~105μm.

8. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 1, characterized in that: The mass fraction of nano-state Prussian blue analogues in the obtained medical 3D printing shape memory composite powder is 1.0~5.0%.

9. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 1, characterized in that: The electromagnetic stirring mixing time is 30~60 minutes.

10. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 1, characterized in that: The temperature for constant temperature electrostatic assembly is 45~65℃, and the duration of constant temperature electrostatic assembly is 60~90min.

11. The method for preparing the medical 3D printing shape memory composite reinforcement material according to claim 9, characterized in that: By mass percentage, the medical shape memory alloy powder contains Ni 52.5~58.5%, Fe ≤ 0.03%, C ≤ 0.05%, Co ≤ 0.01%, Cu ≤ 0.02%, Nb ≤ 0.02%, Cr ≤ 0.01%, H ≤ 0.002%, N ≤ 0.005%, O ≤ 0.01%, with the balance being Ti.

12. A medical 3D printing shape memory composite reinforcement material, characterized in that: Prepared by the preparation method according to any one of claims 1-11.

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