A method for preparing a biomaterial layered isomorphic graphene magnesium-based composite material

Abstract

This invention discloses a method for preparing biomedical layered heterogeneous graphene-magnesium-based composite materials. The method involves depositing graphene oxide onto magnesium-based alloy sheets using electrophoretic deposition. By varying the deposition time and the initial graphene thickness, layered graphene-magnesium-based composite materials with different structural parameters are constructed. The composite materials are then subjected to spark plasma sintering and multiple rolling steps to obtain the biomedical layered heterogeneous graphene-magnesium-based composite material. This method can reduce the degradation rate of bio-magnesium alloys in vivo, increase the service life of biomedical magnesium alloys in the human body environment, and simultaneously improve the strength and toughness of the material itself.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composites technology, and more specifically to a method for preparing biomedical layered heterogeneous graphene magnesium matrix composites. Background Technology

[0002] Graphene is prone to agglomeration, which prevents it from fully utilizing its structural advantages of ultra-large specific surface area; the poor wettability of graphene at the magnesium matrix interface affects interfacial bonding; graphene has a low density and tends to float on the surface of magnesium alloy melts, making it difficult to distribute uniformly within the magnesium matrix, and sometimes even impossible to incorporate into the matrix material, resulting in a low success rate in the preparation of composite materials; biomedical magnesium alloys degrade rapidly in vivo and are highly susceptible to degradation in Cl-containing environments. - Pitting corrosion in corrosive environments limits the clinical application of bio-magnesium alloys in biomedicine. Currently, most researchers address these issues using pretreatments such as ultrasonic dispersion, ball milling, and graphene modification; however, these methods are likely to damage the graphene reinforcement and alter the graphene structure.

[0003] For metallic materials, simultaneously possessing high strength and good ductility has always been a challenging problem for the academic community. The emergence of layered metal matrix composites provides a reliable approach to solving this problem. Inspired by biomimicry, layered metal matrix composites have been found to significantly improve the strength and toughness of materials in nature, as evidenced by the layered stacking structure of seashells. This led to the concept of layered composite structures, allowing the creation of composite materials with the superior properties of both materials using two different properties. For biomedical magnesium alloys, the urgent technical challenge is how to introduce layered carbon materials with poor water wettability to reduce the degradation rate of bio-magnesium alloys in vivo and increase their lifespan in the human body environment. Summary of the Invention

[0004] In view of this, one objective of the present invention is to provide a method for preparing biomedical layered heterogeneous graphene magnesium-based composite materials. This method achieves the synthesis of biomedical layered heterogeneous graphene magnesium-based composite materials by employing steps such as graphene oxide electrophoretic deposition, spark plasma sintering, and multi-pass rolling. The biomedical magnesium alloy prepared by the method of the present invention has good mechanical properties, and its corrosion resistance can be effectively controlled by the magnesium alloy composition. Another objective of the present invention is to provide biomedical layered heterogeneous graphene magnesium-based composite materials prepared by the aforementioned method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] 1. A method for preparing biomedical layered isomeric graphene-magnesium matrix composites.

[0007] Graphene oxide was deposited onto magnesium-based alloy sheets using electrophoretic deposition. By changing the deposition time and the initial graphene thickness, layered graphene-magnesium-based composite materials with different structural parameters were constructed. Then, through spark plasma sintering and multiple rolling steps, the biomedical layered heterogeneous graphene-magnesium-based composite material was synthesized.

[0008] The present invention preferably includes the following steps:

[0009] (1) Graphene was acidified by mixed acid, heated in a water bath, washed and dried to obtain graphene oxide.

[0010] (2) Graphene oxide was ultrasonically dispersed in isopropanol solution, and then the electrolyte Al(NO3)3 was added and ultrasonically mixed.

[0011] (3) Using a stainless steel plate as the anode and a magnesium-based alloy sheet as the cathode, graphene oxide is electrophoretically deposited onto the magnesium-based alloy sheet in the electrolyte solution prepared in step (2).

[0012] (4) Prepare composite material blocks by performing spark plasma sintering in a closed graphite mold with 25 pieces as a group;

[0013] (5) By rolling or hot extrusion deformation treatment, the layered structure of the composite material is regulated and the interlayer bonding is strengthened to obtain biomedical layered heterogeneous graphene magnesium-based composite material.

[0014] Preferably, in step (2) of this invention, the concentration of graphene oxide is 0.05 g / L and the concentration of Al(NO3)3 is 0.01 g / L.

[0015] Preferably, in step (3) of the present invention, the magnesium-based alloy comprises 6% Zn, 1% Nd and 0.5% Ca by mass.

[0016] In the preferred embodiment of the present invention, in step (3), under the conditions of a voltage of 30V and an electrode distance of 50mm, the electrophoretic deposition time is: 0min for layers 1-5, 4min for layers 6-10, 6min for layers 11-15, 8min for layers 16-20, and 10min for layers 21-25.

[0017] Preferably, in step (3) of the present invention, the magnesium-based alloy sheet has a length of 30 mm, a width of 20 mm, and a thickness of 0.2 mm.

[0018] In a preferred embodiment of the present invention, the sintering conditions in step (4) are: 40 MPa, 540 °C for 8 min.

[0019] In a preferred embodiment of the present invention, in step (5), the rolling conditions are: rolling at 400°C with a small deformation of 8% in multiple passes, and after 5 rolling deformations, the total deformation can reach 40%.

[0020] 2. Biomedical layered isomeric graphene-magnesium matrix composite material prepared by the method described above.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention attaches graphene to a magnesium substrate via electrophoretic deposition, thus solving the problem of graphene's tendency to agglomerate in the substrate.

[0023] (1) The present invention uses the spark plasma sintering process to prepare sintered bulk material. The contact area between each matrix sheet will be reduced. The graphene particles mixed in will increase the current density here, thereby increasing the local problem of the contact between graphene particles and magnesium matrix, enhancing the bonding between sheets and the bonding between graphene and matrix.

[0024] (2) By changing the deposition time and adjusting the initial graphene thickness, layered graphene-magnesium-based composite materials with different structural parameters were constructed. The design was based on the principle that as bone healing improves in biomedical applications, the tensile strength and corrosion resistance of magnesium alloys need to gradually decrease, which is consistent with the basic laws of human rehabilitation.

[0025] (3) Through multiple passes of small deformation rolling or hot extrusion, the bonding between the layers and between graphene and the matrix is ​​strengthened again, which further promotes the dispersion of graphene. Attached Figure Description

[0026] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration:

[0027] Figure 1 A flowchart illustrating the preparation of layered isomeric graphene-magnesium-based composite materials for biomedical applications;

[0028] Figure 2 A schematic diagram of the sintering process for biomedical layered isomeric graphene-magnesium-based composite materials;

[0029] Figure 3 The image shows the outermost layer morphology of the final layered heterogeneous graphene-magnesium composite material. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0031] Example 1: A method for preparing a biomedical layered isomeric graphene-magnesium-based composite material.

[0032] Graphene films coated with Mg-6Zn-1Nd-0.5Ca magnesium alloy were prepared by electrodeposition, then stacked into 25 layers, sintered in a spark plasma sintering furnace, and finally formed into layered carbon nanotube magnesium-based composite materials by hot rolling.

[0033] The flowchart for the preparation of biomedical layered isomeric graphene magnesium-based composite materials is as follows: Figure 1 As shown in the diagram, a schematic diagram of the sintering process for biomedical layered isomeric graphene-magnesium-based composite materials is presented. Figure 2 As shown.

[0034] The specific steps of Option 1 are as follows:

[0035] (1) Mg-6Zn-1Nd-0.5Ca magnesium alloy ingots were prepared in a vacuum melting furnace and then cut into thin sheets with a length of 30 mm, a width of 20 mm, and a thickness of 0.2 mm on a wire cutting machine.

[0036] (2) The thin film is polished with SiC sandpaper, cleaned with ethanol and acetone solution, dried and stored for later use;

[0037] (3) Acidify the graphene with mixed acid (concentrated nitric acid: concentrated sulfuric acid = 1:3), heat it in a water bath at 70°C for 5 hours, and repeatedly dilute and filter it until there is no residual acid. Then dry and store it.

[0038] (3) Disperse the pretreated GNPs in isopropanol solution at a concentration of 0.05 g / L and sonicate for 5 h. Add Al(NO3)3 electrolyte at a concentration of 0.01 g / L and continue to sonicate to disperse the electrolyte for 2 h.

[0039] (4) Construct an electrophoretic deposition apparatus, using a stainless steel plate as the anode and a magnesium alloy sheet as the cathode, with a fixed distance of 50 mm between the plates. The voltage is 30V. Electrophoretic deposition is performed for layers 1-5 for 0 min, layers 6-10 for 4 min, layers 11-15 for 6 min, layers 16-20 for 8 min, and layers 21-25 for 10 min.

[0040] (5) GNPs / Mg layered composite material blocks were prepared by spark plasma sintering in a sealed graphite mold in groups of 25 pieces under the following conditions: 40 MPa, 540 °C for 8 min. After furnace cooling, the GNPs / Mg layered composite material blocks were prepared.

[0041] (6) The layered structure of composite materials is controlled and the interlayer bonding is strengthened by rolling or hot extrusion deformation treatment;

[0042] The rolling conditions are as follows: rolling is carried out at 400℃ with a small deformation of 8% in multiple passes. After five rolling deformations, the total deformation can reach 40%. A 20-minute homogenization preheating is performed before the first pass, and a 5-minute annealing treatment is performed between each pass to eliminate stress and improve the deformation capacity.

[0043] The mechanical properties of the layered composite material prepared using Scheme 1 are as follows: yield strength 238 MPa, elongation 11.1%, and corrosion rate in simulated body fluid 1.272 g / (m²). 2 •h). The total mass of graphene accounts for 0.6% of the mass of the magnesium-based composite material, but the mass of graphene in different magnesium-based alloy sheets accounts for 0-0.9% of the mass of the magnesium-based composite material. The outermost layer morphology of the final formed layered heterogeneous graphene magnesium-based composite material is as follows. Figure 3 As shown.

[0044] Comparative Example 1: All 25 layers were not electrodeposited; the composite material was sintered by spark plasma at 540℃ and 40MPa for 8 minutes. The mechanical properties of the rolled layered composite material were: yield strength 156MPa, elongation 4.1%, and corrosion rate in simulated body fluid 1.722g / (m³). 2 ·h).

[0045] Comparative Example 2: All 25 layers were deposited by electrophoresis for 4 minutes, followed by spark plasma sintering at 460℃ and 40MPa for 8 minutes. The mechanical properties of the rolled layered composite material were: yield strength 188MPa, elongation 4.5%, and corrosion rate in simulated body fluid 1.645g / (m³). 2 ·h).

[0046] Comparative Example 3: All 25 layers were deposited by electrophoresis for 4 minutes, followed by spark plasma sintering at 500℃ and 40MPa for 8 minutes. The mechanical properties of the rolled layered composite material were: yield strength 201MPa, elongation 8.7%, and corrosion rate in simulated body fluid 1.341g / (m³). 2 ·h).

[0047] Comparative Example 4: All 25 layers were deposited by electrophoresis for 4 minutes, followed by spark plasma sintering at 540℃ and 40MPa for 8 minutes. The mechanical properties of the rolled layered composite material were: yield strength 234MPa, elongation 12.2%, and corrosion rate in simulated body fluid 1.122g / (m³). 2 ·h).

[0048] Comparative Example 5: All 25 layers were deposited by electrophoresis for 4 minutes, followed by spark plasma sintering at 580℃ and 40MPa for 8 minutes. The mechanical properties of the rolled layered composite material were: yield strength 198MPa, elongation 9.1%, and corrosion rate in simulated body fluid 1.522g / (m³).2 ·h).

[0049] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A biomedical layered isomeric graphene-magnesium-based composite material, characterized in that, The preparation method is as follows: graphene oxide is deposited onto magnesium-based alloy sheets using electrophoretic deposition. By changing the deposition time, layered graphene-magnesium-carbon composite materials with different structural parameters are constructed. Then, through spark plasma sintering and multiple rolling steps, biomedical layered heterogeneous graphene-magnesium-based composite materials are obtained. The specific steps include the following: (1) Graphene was acidified by mixed acid, heated in a water bath, washed and dried to obtain graphene oxide. (2) Graphene oxide is ultrasonically dispersed in isopropanol solution, and then the electrolyte Al(NO3)3 is added and ultrasonically mixed; the concentration of graphene oxide is 0.05 g / L and the concentration of Al(NO3)3 is 0.01 g / L. (3) Using a stainless steel plate as the anode and a magnesium-based alloy sheet as the cathode, graphene oxide is electrophoretically deposited onto the magnesium-based alloy sheet in the electrolyte solution prepared in step (2). The composition of the magnesium-based alloy sheet is Mg-6Zn-1Nd-0.5Ca by mass fraction. The size of the magnesium-based alloy sheet is 30mm long, 20mm wide, and 0.2mm thick. Under the conditions of a voltage of 30V and an electrode distance of 50mm, the electrophoretic deposition time is: 0min for layers 1-5, 4min for layers 6-10, 6min for layers 11-15, 8min for layers 16-20, and 10min for layers 21-25. (4) The 25-layer magnesium-based alloy sheets obtained in step (3) are used as a group and are subjected to spark plasma sintering in a closed graphite mold to prepare a composite material block; the sintering conditions are: 40MPa, 540℃ for 8min. (5) By rolling or hot extrusion deformation treatment, the layered structure of the composite material is regulated and the interlayer bonding is strengthened to obtain biomedical layered heterogeneous graphene magnesium-based composite material. The rolling conditions are as follows: rolling is carried out at 400°C with a small deformation of 8% in multiple passes, and after 5 rolling deformations, the total deformation reaches 40%.

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