High-strength and antibacterial biomedical implant, Ti alloy, molded body, and method for manufacturing the Ti alloy.

Abstract

To provide a biocompatible implant with excellent mechanical properties and antibacterial properties. [Solution] The biomedical implant contains element M selected from Cu, Ag, and Zn, and element X selected from O, C, and N, with the remainder being Ti and unavoidable impurities.

Description

[Technical Field]

[0001] This invention relates to a biomedical implant having high strength and antibacterial properties, a Ti alloy, a molded body, and a method for manufacturing the Ti alloy. [Background technology]

[0002] Titanium (Ti) alloys are widely used in the medical field due to their lightweight, non-magnetic, corrosion-resistant, and biocompatible properties. Conventional dental implants use Ti or Ti64 alloy (Ti-6Al-4V) (Non-Patent Document 1).

[0003] Conventional dental implants are manufactured, for example, by casting or 3D printing (Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Haize Galarraga et al., Effects of the microstructure and porosity on properties of Ti-6Al-4VELI alloy fabricated by electron beam melting (EBM), Additive Manufacturing 10 (2016), 47-57 [Non-Patent Document 2] Rajkumar Velu, et al., A Comprehensive Review on Bio-Nanomaterials for Medical Implants and Feasibility Studies on Fabrication of Such Implants by Additive Manufacturing Technique, Materials 2020, 13, 92; doi:10.3390 / ma13010092, 1-23 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, dental implants made with Ti or Ti64 alloys have low antibacterial properties, making them susceptible to bacterial infection and low resistance to inflammation, which can lead to rapid progression of infection once it occurs. Furthermore, similar to general periodontal disease, bacterial infection can occur around the implant, raising concerns about bone destruction and osteolysis. In addition, although Ti64 alloy has higher mechanical strength than Ti, its strength as an implant is not considered sufficient, and there are concerns that its insufficient strength may limit its lifespan. Furthermore, conventional methods for manufacturing dental implants, as described above, require multiple steps such as casting, molding, and machining, resulting in high costs and making customization for individual users difficult. Additionally, there are concerns that the formation of coarse compounds during the casting process may lead to copper segregation, reducing antibacterial properties.

[0006] The present invention aims to provide a biocompatible implant, a Ti alloy, a molded body, and a method for manufacturing the Ti alloy that are excellent in both mechanical properties and antibacterial properties, and that can be easily customized at low cost. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides the following configuration. [1] A biomedical implant comprising element M selected from Cu, Ag, and Zn, and element X selected from O, C, and N, with the remainder being Ti and unavoidable impurities. [2] A step (A) of mixing Ti powder with a powder of a compound containing element M selected from Cu, Ag and Zn, and element X selected from O, C and N, (B) A step of drying a mixture of Ti powder and the powder of the compound, A method for producing a Ti alloy, comprising the step (C) of adding thermal energy to the mixture after drying to melt the mixture. [3] The method for producing a Ti alloy according to [2], wherein in the step (C), the mixture is melted by a laser powder bed fusion method. [4] The method for producing a Ti alloy according to [2] or [3], wherein when the mass of Ti in the mixture is 100% by mass, the content of the compound is 0.1% by mass or more and 30% by mass or less. [5] The method for producing a Ti alloy according to [2] or [3], wherein the compound is CuO. [6] A Ti alloy comprising an element M selected from Cu, Ag and Zn, an element X selected from O, C and N, with the balance being Ti and unavoidable impurities. [7] The Ti alloy according to [6], wherein when the total mass of the Ti alloy is 100% by mass, the mass of the element M is 0.1% by mass or more and 20% by mass or less. [8] The Ti alloy according to [6] or [7], wherein when the total mass of the Ti alloy is 100% by mass, the mass of the element X is 0.01% by mass or more and 3.0% by mass or less. [9] The Ti alloy according to [6] or [7], wherein the element M is Cu and the element X is O.

[10] comprising an α phase and an α' phase of Ti, The Ti alloy according to [9], wherein Cu is solid-dissolved in at least the α' phase.

[11] A shaped article comprising the Ti alloy according to [6] or [7]. Effects of the Invention

[0008] According to the present invention, there can be provided a biomedical implant, a Ti alloy, a shaped article, and a method for producing a Ti alloy which are excellent in both mechanical properties and antibacterial properties, and can achieve low-cost and easy customization. Brief Description of Drawings

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of a method for producing a Ti alloy according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of a method for adding fine foam in the method for producing a Ti alloy of FIG. 1. [Figure 3] Figure 3 is a diagram showing consideration on the microstructure structure of Ti-1 mass% CuO obtained by laser irradiation, as an example of Ti alloys according to embodiments of the present invention. [Figure 4] Figures 4(a) to 4(d) are electron microscope images showing a mixture of Ti powder and CuO powder used in Examples and Comparative Examples. [Figure 5A] Figure 5A is a diagram showing the correlation between production conditions in Examples and Comparative Examples, and microscope images of a shaped article of the Example formed of CuO-containing Ti alloy and a shaped article of the Comparative Example formed of Ti. [Figure 5B] Figure 5B is a diagram showing the correlation between production conditions in Examples and Comparative Examples, and relative densities of a shaped article of the Example formed of CuO-containing Ti alloy and a shaped article of the Comparative Example formed of Ti. [Figure 6] Figure 6 is a diagram showing X-ray diffraction (XRD) results of a shaped article of the Example formed of CuO-containing Ti alloy and a shaped article obtained in the Comparative Example formed of Ti. [Figure 7] Figure 7 is a diagram showing results of microstructure observation and element mapping of a shaped article of the Example formed of CuO-containing Ti alloy. [Figure 8] Figures 8(a) to 8(c) are diagrams showing TEM images and results of crystal structure analysis by electron diffraction of a shaped article of the Example formed of CuO-containing Ti alloy. [Figure 9A] Figure 9A is a diagram showing results of elemental analysis by EDS of a shaped article of the Example formed of CuO-containing Ti alloy. [Figure 9B] Figure 9B is a diagram showing results of elemental analysis by EDS of a shaped article of the Example formed of CuO-containing Ti alloy. [Figure 10] Figures 10(a) to 10(b) are diagrams showing mechanical properties of a shaped article of the Example formed of CuO-containing Ti alloy. [Figure 11] Figure 11 is a diagram showing comparison of mechanical properties between a shaped article of the Example formed of CuO-containing Ti alloy and a shaped article formed of another Ti alloy. [Figure 12]Figures 12(a) and 12(b) show the results of antibacterial tests on molded bodies made of CuO-containing Ti alloy in the examples. [Figure 13] Figure 13 shows the results of other antimicrobial tests on molded bodies made of CuO-containing Ti alloy in the example. [Modes for carrying out the invention]

[0010] <Bioplastic Implants> The biomedical implant according to this embodiment contains element M selected from Cu, Ag, and Zn, and element X selected from O, C, and N, with the remainder being Ti and unavoidable impurities. The biomedical implant is not particularly limited, but is typically a dental implant.

[0011] The mass of element M, when the total mass of the biomedical implant is taken as 100% by mass, is not particularly limited, but is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, and even more preferably 0.1% by mass or more and 5% by mass or less. By having a mass of element M of 0.1% by mass or more and 20% by mass or less, the antibacterial properties can be further improved.

[0012] The mass of element X, when the total mass of the biomedical implant is taken as 100% by mass, is not particularly limited, but is preferably 0.01% by mass or more and 3.0% by mass or less, more preferably 0.1% by mass or more and 1% by mass or less, and even more preferably 0.2% by mass or more and 0.8% by mass or less. By having a mass of element X of 0.01% by mass or more and 3.0% by mass or less, the mechanical strength can be further improved.

[0013] The combination of element M and element X is not particularly limited, but it is preferable that element M is Cu and element X is O. When element M is Cu and element X is O, the antibacterial effect is more strongly expressed by Cu coming into direct contact with bacteria, and the inclusion of O as a solid solution strengthening element further improves antibacterial properties and mechanical strength. Furthermore, because a chemical bond is formed between Ti and Cu, it is stable and does not ionize, and good antibacterial properties can be maintained over a long period of time.

[0014] The biomedical implant preferably contains the α-phase and α'-phase of Ti. The α-phase is a crystalline structure having a hexagonal close-packed (hcp) structure. The α'-phase is a martensite phase having a hexagonal close-packed structure, and is a non-equilibrium crystalline structure produced when the β-phase is rapidly cooled. The inclusion of the α-phase of Ti in the biomedical implant improves corrosion resistance, and the inclusion of the α'-phase of Ti further improves mechanical strength. In this case, it is preferable that the element M is solid-dissolved in at least the α'-phase. It is preferable that Cu, of the element M, is solid-dissolved in at least the α'-phase. Alternatively, Cu, of the element M, may be solid-dissolved in both the α-phase and the α'-phase. The solid-dissolved Cu in at least the α'-phase allows for better antibacterial properties.

[0015] In the biomedical implant of this embodiment, the yield strength may be 900 MPa or more, 1000 MPa or more, or 1100 MPa or more. The tensile strength may be 900 MPa or more, 1000 MPa or more, 1100 MPa or more, or 1200 MPa or more. The growth rate may be 21% or less, 20% or less, or 15% or less. The Vickers hardness may be 250 HV or higher, 300 HV or higher, or 350 HV or higher.

[0016] <Method for Producing Ti Alloy> Fig. 1 is a diagram illustrating an example of a method for producing a Ti alloy according to an embodiment of the present invention. The method for producing a Ti alloy according to the present embodiment comprises: a step (A) of mixing Ti powder with powder of a compound containing an element M selected from Cu, Ag and Zn and an element X selected from O, C and N; a step (B) of drying a mixture of the Ti powder and the powder of the compound; and a step (C) of applying thermal energy to the dried mixture to melt the mixture.

[0017] (Step (A)) In step (A), Ti powder is mixed with the powder of the above compound containing an element M selected from Cu, Ag and Zn and an element X selected from O, C and N. As a mixing method, for example, the powder of the compound is dispersed in deionized water by ultrasonic treatment to prepare a colloidal solution in which the compound is dispersed. Subsequently, Ti powder is added to the colloidal solution under mechanical stirring.

[0018] The average particle diameter of the Ti powder is not particularly limited, but is preferably 10 µm or more and 45 µm or less, more preferably 15 µm or more and 35 µm or less, and still more preferably 20 µm or more and 30 µm or less. The average particle diameter of the powder of the compound containing an element M selected from Cu, Ag and Zn and an element X selected from O, C and N is not particularly limited, but is preferably less than 50 nm, more preferably 30 nm or less, and still more preferably 5 nm or more and 20 nm or less.

[0019] When adding Ti powder to the colloidal solution, microbubbles may also be added together. The microbubbles can be added, for example, by a microbubble generator.

[0020] Fig. 2 is a schematic diagram illustrating an example of a method for adding microbubbles in the method for producing the Ti alloy of Fig. 1. As shown in Figure 2, in step (A), it is preferable to use a powder mixing method using electrostatic force called the heteroaggregation method. In the heteroaggregation method, nanoparticles are attached to the original Ti powder by electrostatic force between particles, enabling uniform powder mixing while maintaining shape, size, and fluidity to the maximum extent. When the two powders to be mixed are charged with different charges, they are mixed by electrostatic attraction and uniform powder production is possible. However, since the zeta potential of pure Ti particles (CP-Ti) is positive and the CuO particles to be mixed also have a positive value, a substance is needed to bridge the powders. Microbubbles, especially ultrafine bubbles (UFB), are fine bubbles with a size of tens to hundreds of nanometers that are generated during the contraction process of fine bubbles, and since they are composed only of water and gas, they do not contain impurities. Also, according to Conway et al., H + and OH - The enthalpy of hydration (ΔH) of H is -1104 kJ / mol and -446.8 kJ / mol, respectively. + It preferentially remains in the water layer, OH - Ions preferentially accumulate at the gas-liquid interface. As a result, the surface of the ultrafine bubbles becomes negatively charged. Therefore, when adding Ti powder to the above colloidal solution, adding fine bubbles along with it allows the negatively charged fine bubbles to adhere to the surface of the positively charged Ti particles, and the positively charged particles of the above compound to adhere more easily to the surface of the Ti particles via the fine bubbles, thereby enabling a more uniform dispersion of the above compound on the Ti particles.

[0021] The average particle size of the microbubbles is not particularly limited, but is preferably 10 nm to 300 nm, more preferably 30 nm to 250 nm, and even more preferably 80 nm to 200 nm.

[0022] The compound containing element M selected from Cu, Ag, and Zn, and element X selected from O, C, and N, is preferably CuO. The presence of CuO in the compound allows for greater antibacterial activity through direct contact between Cu and bacteria, and the inclusion of O as a solid solution strengthening element further enhances antibacterial properties and mechanical strength.

[0023] In the mixture obtained in step (A), the content of the compound is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.1% by mass or more and 20% by mass or less, even more preferably 0.1% by mass or more and 10% by mass or less, and particularly preferably 0.1% by mass or more and 5% by mass or less. By having a compound content of 0.1% by mass or more and 30% by mass or less, in addition to improving mechanical strength, ductility can be improved.

[0024] (Process (B)) In step (B), the mixture of Ti powder and the powder of the above compound is dried. As a drying method, for example, the suspension obtained in step (A) is mixed with liquid nitrogen to produce frozen particles, and the frozen body is vacuum dried to remove water by sublimation. The method of mixing the suspension and liquid nitrogen is not particularly limited; the suspension may be added to the liquid nitrogen, or the liquid nitrogen may be added to the suspension. This forms a dried powder composed of the mixture of Ti powder and the powder of the above compound.

[0025] (Process (C)) In configuration (C), thermal energy is applied to the above mixture after drying to melt it. The mixture is melted by the application of thermal energy, and a Ti alloy is obtained by subsequent slow cooling or cooling. As for the melting method, it is preferable to melt the above mixture by laser powder bed fusion (L-PBP). When using laser powder bed fusion, for example, a powder bed is prepared by spreading a dry powder mixture consisting of Ti powder and the above compound powder in an inert environment, and a laser is irradiated onto the powder bed. By repeatedly and alternately spreading the above particle powder and scanning the powder bed with a laser, a molded body made of Ti alloy can be formed. By using L-PBP, supersaturated solid solution is achieved by rapid cooling solidification by laser irradiation, and the formation of coarse compounds can be suppressed. In addition, shape control is easy, multi-product / small-batch production can be easily carried out, and yield can be improved.

[0026] When using laser powder bed fusion fusion, specify the type of laser, laser power p (W), scanning speed v (mm / s), hatch spacing h (μm), layer thickness t (μm), and energy density Ev (J / mm²). 3 The material is not particularly limited, provided that it can form a Ti alloy. As an inert environment, for example, Ar (oxygen concentration less than 0.1%) can be used. As for the type of laser, a general fiber laser, such as a ytterbium laser (wavelength 1030-1070 nm), can be used, and special lasers such as the blue laser (wavelength 400-450 nm) used for Ti are not required.

[0027] The laser output p (W) is preferably 65 W to 95 W, more preferably 80 W to 95 W, and still more preferably 90 W to 95 W. The scanning speed is preferably 400 to 1200 mm / s, more preferably 600 mm / s to 1200 mm / s, and still more preferably 800 mm / s to 1000 mm / s. The hatch spacing is preferably 80 to 100 µm, more preferably 80 µm to 90 µm, and still more preferably 85 to 90 µm. The layer thickness is preferably 10 µm to 50 µm, more preferably 15 µm to 35 µm, and still more preferably 20 µm to 25 µm. The energy density is 20 J / mm 3 to 110 J / mm 3 , preferably 20 J / mm 3 to 80 J / mm 3 , more preferably 20 J / mm 3 to 40 J / mm 3 , and even more preferably within this range.

[0028] Figure 3 is a diagram showing an analysis of the microstructure of Ti-1 mass% CuO obtained by laser irradiation, as an example of the Ti alloy according to an embodiment of the present invention. As shown in Figure 3, when a dry powder composed of a mixture of Ti powder and CuO powder is irradiated with a laser, Marangoni convection occurs in the vicinity of CuO aggregates in the molten region. Cu and O are generated through decomposition of CuO, and a β phase is formed. Thereafter, martensitic transformation occurs due to rapid solidification of the β phase, forming a solid solution of Cu and O (α' phase). Along with this, regions with high Cu concentration are formed near the grain boundaries of the base material.

[0029] <Ti alloy> The Ti alloy according to the present embodiment contains an element M selected from Cu, Ag and Zn, an element X selected from O, C and N, with the balance being Ti and unavoidable impurities.

[0030] The mass of element M, when the total mass of the Ti alloy is 100% by mass, is not particularly limited, but is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, and even more preferably 0.1% by mass or more and 5% by mass or less. By having a mass of element M of 0.1% by mass or more and 20% by mass or less, the antibacterial properties can be further improved.

[0031] The mass of element X when the total mass of the Ti alloy is 100% by mass is not particularly limited, but is preferably 0.01% by mass or more and 3.0% by mass or less, more preferably 0.1% by mass or more and 1% by mass or less, and even more preferably 0.2% by mass or more and 0.8% by mass or less. By having a mass of element X of 0.01% by mass or more and 3.0% by mass or less, the mechanical strength can be further improved.

[0032] The combination of element M and element X is not particularly limited, but it is preferable that element M is Cu and element X is O. When element M is Cu and element X is O, the antibacterial effect is more strongly expressed when Cu comes into direct contact with bacteria, and the antibacterial properties and mechanical strength can be further improved by the inclusion of O as a solid solution strengthening element.

[0033] The Ti alloy preferably contains the α-phase and α'-phase of Ti. The α-phase is a crystalline structure having a hexagonal close-packed (hcp) structure. The α'-phase is a martensite phase having a hexagonal close-packed structure, and is a non-equilibrium crystalline structure formed when the β-phase is rapidly cooled. The inclusion of the α-phase of Ti in the Ti alloy improves corrosion resistance, and the inclusion of the α'-phase of Ti further improves mechanical strength. In this case, it is preferable that the element M is dissolved in at least the α'-phase, and it is preferable that Cu, of the element M, is dissolved in at least the α'-phase. Alternatively, Cu, of the element M, may be dissolved in both the α-phase and the α'-phase. The presence of Cu dissolved in at least the α'-phase allows for better antibacterial properties.

[0034] In the Ti alloy of this embodiment, the yield strength may be 900 MPa or more, 1000 MPa or more, 1100 MPa or more, or 1200 MPa or more. The tensile strength may be 900 MPa or more, 1000 MPa or more, or 1100 MPa or more. The growth rate may be 21% or less, 20% or less, or 15% or less. The Vickers hardness may be 250 HV or higher, 300 HV or higher, or 350 HV or higher.

[0035] <Sculpture> The molded body according to this embodiment contains the above-mentioned Ti alloy. The molded body is not particularly limited and can be any various parts used in the medical field, etc. Specific examples of molded bodies include, for example, medical-related components, medical device components, and instruments where antibacterial properties are required. More specifically, examples include surgical instruments, dental instruments, medical device exterior components, hospital equipment components, food processing equipment components, cooking utensils, and contact components for public facilities (door handles, handrails, etc.). The Ti alloy content when the total mass of the molded body is 100% by mass is not particularly limited and can be set according to the application. Furthermore, it is preferable that the molded body is made of the above-mentioned Ti alloy. [Examples]

[0036] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples.

[0037] (Example 1) A colloidal solution was prepared by mixing CuO powder (manufactured by SIGMA-ALDRICH, average particle size 40 nm) with deionized water and stirring for 20 minutes using a stirrer and ultrasonic horn to disperse the CuO powder in the deionized water. Next, pure Ti powder (manufactured by AP&C Inc., average particle size 32 μm) was added to the colloidal solution so that the CuO content in the mixture was 1% by mass, with the mass of pure Ti being 100% by mass. Furthermore, microbubble water (average particle size 167 nm) was added using a microbubble generator (manufactured by the Institute of Ultrafine Science, device name "Nanobubble Generator"), and the mixture was stirred with a stirrer for 30 minutes to prepare a suspension containing a mixture in which CuO particles were attached to the surface of pure Ti particles. Next, the above suspension was dropped into liquid nitrogen to produce frozen particles, and the frozen material was vacuum-dried at 228K in a freeze-dryer (EYELA Corporation, equipment name "FDU-1200") to obtain a powder composed of a mixture of Ti powder and CuO powder. Using an additive manufacturing system (Concept Laser, name "Mlab R"), a powder bed was prepared by laying the powder obtained above in an Ar environment (oxygen concentration less than 0.1%) using the Laser Powder Bed Fusion (L-PBF) method. A laser was then irradiated onto the powder bed, and the process of laying the powder and scanning the powder bed with the laser was repeated alternately 240 times to form a structure made of Ti alloy. The laser irradiation conditions were as follows.

[0038] Laser type: Ytterbium (Yb) fiber laser (wavelength 1070 nm) Laser output p: 95W Scanning method: island method Scanning speed v: 1200 mm / s Hatch spacing h: 90 μm Layer thickness t: 25μm Energy density Ev: 105.6 J / mm² 3

[0039] (Example 2) A molded body made of a Ti alloy was formed in the same manner as in Example 1, except that the CuO content in the above mixture was adjusted to 1.5% by mass when the mass of Ti was set to 100% by mass. (Example 3) A molded body made of a Ti alloy was formed in the same manner as in Example 1, except that the CuO content in the above mixture was adjusted to 2.0% by mass when the mass of Ti was set to 100% by mass.

[0040] (Example 4) Among the laser irradiation conditions, the energy density was set to 35.2 J / mm². 3 Aside from the change made to the above, a molded body made of Ti alloy was formed in the same manner as in Example 1.

[0041] (Example 5) Among the laser irradiation conditions, the energy density was set to 28.9 J / mm². 3 Except for the change made to the above, three molded bodies made of Ti alloy were formed in the same manner as in Example 1.

[0042] (Comparative Example 1) A molded body composed of pure Ti was formed in the same manner as in Example 1, except that CuO powder was not added.

[0043] (Comparative Example 2) Among the laser irradiation conditions, the energy density was set to 35.2 J / mm². 3 Apart from the change, a molded body made of pure Ti was formed in the same manner as in Comparative Example 1.

[0044] (Comparative Example 3) Among the laser irradiation conditions, the energy density was set to 28.9 J / mm². 3 Apart from the change, a molded body made of pure Ti was formed in the same manner as in Comparative Example 1.

[0045] The powders used in the examples and comparative examples, and the molded bodies obtained in the examples and comparative examples, were measured and evaluated using the following methods.

[0046] [Electron Microscope Observation] The powder composed of a mixture of Ti powder and CuO powder used in the examples was observed using an electron microscope. The powder composed of pure Ti used in the comparative example was also observed using an electron microscope. Furthermore, the fabricated bodies obtained in the examples and comparative examples were observed using a scanning electron microscope (SEM).

[0047] [X-ray diffraction (XRD) measurement] X-ray diffraction measurements were performed using the 2θ / θ method with an X-ray diffractometer (manufactured by Rigaku Holdings, model name "SmartLab 9kW") and JADE analysis software. The X-ray diffraction measurements were performed under the following conditions: scan speed of 2 degrees / min, scan range of 30-80 degrees, and step size of 0.02 degrees.

[0048] [Tissue observation and elemental mapping] Crystal structure analysis was performed using a scanning electron microscope with an energy-dispersive X-ray analyzer (JOEL Corporation, instrument name "JSM-6010LV"), based on secondary electron imaging. The crystal structure analysis was performed under conditions of a tube voltage of 15 kV and a tube current of 90 μA.

[0049] [Crystal structure analysis] Crystal structure analysis was performed using a high-resolution transmission electron microscope (Hitachi, Ltd., model name "HF-2000EDX") and selective region electron diffraction (SAED) patterns. The crystal structure analysis was performed under an acceleration voltage of 200 kV.

[0050] [Elemental analysis] Using a SEM-EDX (manufactured by JOEL, instrument name "JSM-6010LV"), the surface of the fabricated bodies obtained in the examples and comparative examples was observed, and the distribution of elements Ti, Cu, and O was measured.

[0051] [Evaluation of mechanical properties] Yield stress, tensile strength, elongation, and Vickers hardness were measured in accordance with JIS Z 2241 and JIS Z 2244. The results are shown in Tables 1 and 2.

[0052] [Table 1]

[0053] [Table 2]

[0054] As shown in Figures 4(b) to 4(d), it was confirmed that the amount of CuO particles adhering to the surface of the Ti particles in the mixtures used in Examples 1 to 3 increased with increasing CuO content. Furthermore, CuO aggregation was observed as the CuO concentration in the mixture increased. In addition, as shown in Figure 4(a), it was confirmed that nothing was adhering to the surface of the pure Ti particles used in the comparative example. When the laser absorptivity of the CuO-containing Ti particle powder used in Examples 1 to 3 and the pure Ti particle powder used in the comparative example was measured, it was confirmed that the CuO-containing Ti particles used in Examples 1 to 3 maintained the same laser absorptivity as the pure Ti particles used in Comparative Example 1, even after the addition of CuO particles.

[0055] As shown in Figures 5A and 5B, under low energy density conditions, (28.9 J / mm²) 3 ), defects due to insufficient melting were observed in all molded bodies of Examples 1, 4, and 5, and Comparative Examples 1 to 3. Furthermore, under high energy density conditions (105.6 J / mm²), 3 ), defects called keyholes, caused by metal evaporation, were observed. Under medium energy density conditions (35.2 J / mm²), 3 No defects were observed in the molded body of Example 4. On the other hand, a small number of defects due to insufficient melting were observed in the molded body of Comparative Example 2. Furthermore, as shown in Figure 5B, in Examples 1, 4, and 5, which used a Ti-1 mass%CuO mixture, it was found that high-density fabricated bodies could be obtained under the same energy density conditions compared to Comparative Examples 1-3, which used pure Ti particles. It was also found that by optimizing the energy density, high-density structures with a relative density exceeding 99% can be achieved.

[0056] As shown in Figure 6, it was confirmed that the α and α' phases of Ti in the fabricated bodies of Examples 1 to 3 were composed of a hexagonal close-packed structure. Furthermore, as shown in Table 1, it was confirmed that the lattice constant of the a-axis tended to increase with increasing CuO content.

[0057] As shown in Figure 7, needle-shaped crystals, considered to be the α' phase (martensite phase), were observed in the fabricated bodies of Examples 1-2 and Comparative Example 1. Furthermore, no segregation of Cu and O occurred in the fabricated bodies of Examples 1-2, and they were uniformly distributed in the matrix. In addition, the concentrations of Ti, Cu, and O in the fabricated bodies of Examples 1-2 were consistent with the concentrations of Ti, Cu, and O in the CuO-containing Ti particle powder, respectively.

[0058] As shown in Figures 8(a) to 8(c), a long, plate-like (lath-like) α' phase (martensite phase) was observed in the fabricated bodies of Examples 1 and 2 and Comparative Example 1. Furthermore, the lath thickness of the α' phase in the fabricated bodies of Examples 1 and 2 was 0.37 μm and 0.34 μm, respectively, while the lath thickness of the α' phase in the fabricated body of Comparative Example 1 was 0.45 μm. From these results, it was confirmed that the lath thickness decreased when CuO α was added to Ti, and that the lath thickness tended to decrease with increasing CuO content. In addition, nanoparticles were observed in the fabricated bodies of Examples 1 and 2.

[0059] As shown in Figure 9A, in the fabricated body of Example 1, nanoparticles were distributed along the grain boundaries of the martensite phase, and these nanoparticles showed a high Cu concentration of approximately 20 at%. In addition to the nanoparticles with high Cu concentration, solid solution of Cu was observed in the matrix material, particularly near the grain boundaries. Furthermore, as shown in Figure 9B, in the fabricated body of Example 2, nanoparticles with high Cu concentration were randomly distributed in the matrix and partially aggregated. Solid solution of Cu was also observed in the base material, suggesting that the CuO particles were partially melted.

[0060] As shown in Figure 10(a), it was found that the strength of all the molded bodies in Examples 1 to 3 was higher than that of the molded body in Comparative Example 1. Furthermore, it was found that the strength of the molded bodies in Examples 1 to 3 increased significantly with increasing CuO content. In addition, it was found that the molded body in Example 1, which is Ti-1 mass%CuO, showed improved strength while maintaining high elongation compared to the molded body in Comparative Example 1, which is pure Ti. Furthermore, as shown in Figure 10(b) and Table 2, the calculated toughness values ​​revealed that the fabricated bodies of Examples 1 and 2 had higher toughness compared to the fabricated body of Comparative Example 1. In particular, the fabricated body of Example 1, which is Ti-1 mass%CuO, was found to have the best balance of strength and ductility.

[0061] As shown in Figure 11, all of the fabricated bodies from Examples 1 to 3 were found to exhibit tensile strength comparable to that of Ti64 alloy (Ti-6Al-4V). In particular, the fabricated body of Example 1, which is Ti-1 mass%CuO, and the fabricated body of Example 2, which is Ti-1.5 mass%CuO, were found to exhibit a better balance of strength and ductility than Ti64 alloy and Ti-Cu alloy.

[0062] [Antibacterial evaluation test] The antibacterial test was conducted using the film adhesion method in accordance with JIS Z 2801 (Antibacterial processed products - Antibacterial test methods and antibacterial effects). (1) Cleaning of metal samples and samples for antimicrobial evaluation As a test sample, a Ti alloy plate material, which is Ti-1 mass%CuO as the fabricated object of Example 1, was prepared by laser powder bed fusion (L-PBF). As a comparative example, a pure Ti plate material was prepared by the L-PBF method, and a known industrial pure Ti plate material was also prepared. The laser irradiation conditions were the same as above. Each sample was processed to have a diameter of approximately 8 mm and uniform thickness, and the test surface was mirror-polished. After polishing, surface contaminants were removed by ultrasonic cleaning in acetone and isopropanol. Subsequently, sterilization was performed using 70% by volume ethanol, followed by washing with ultrapure water and phosphate-buffered saline (PBS(-)), and then the samples were subjected to testing under sterile conditions.

[0063] (2) Preparation of test bacteria and bacterial suspension The test organisms used were Escherichia coli (JCM 5491), a Gram-negative bacterium, and Staphylococcus aureus (JCM2413), a Gram-positive bacterium. Each bacterial strain was pre-cultured on a standard Nutrient agar medium, and then a bacterial suspension was prepared using physiological salt. The number of bacteria in the bacterial suspension was measured using a spectrophotometer to determine the OD600 count, which was approximately 1.0 × 10⁶ at the start of the test using physiological salt. 6 After dilution to a CFU / mL concentration, the number of viable cells (CFU) was confirmed by plate culture.

[0064] (3) Antimicrobial test (film adhesion method) A predetermined amount of bacterial suspension was dropped onto the evaluation surface of each test sample, and a sterile film was then placed in close contact with it. This ensured that the bacterial suspension was in uniform contact with the entire surface of the sample. This test was conducted in accordance with JIS Z 2801, with an initial bacterial concentration of 10 5 ~10 6 By seeding a bacterial suspension of CFU / mL in a predetermined volume, substantially 10 units per unit area of ​​the test specimen are obtained. 2 ~10 3 The procedure was carried out under conditions that resulted in a CFU level. Subsequently, the cells were incubated at 37°C for 24 hours in an incubator.

[0065] (4) Recovery and measurement of viable bacteria After the culture was complete, bacteria were collected from the sample surface and film using a predetermined recovery solution. The recovery solution was serially diluted and seeded onto Nutrient agar medium. After 24 hours of incubation, the number of colonies formed was counted to calculate the number of viable bacteria (CFU).

[0066] (5) Statistical analysis Analysis of variance (ANOVA) was performed on the viable cell count data obtained from each sample, followed by multiple comparisons using t-tests. The criterion for statistical significance was p<0.05.

[0067] As shown in Figure 12(a), an antimicrobial test using E. coli confirmed that the Ti alloy plate material used as the molded body in Example 1, which is Ti-1 mass%CuO, exhibited superior antimicrobial effects compared to the pure Ti plate material produced by the L-PBF method and the known industrial pure Ti plate material. Furthermore, as shown in Figure 12(b), a cell proliferation test confirmed that the Ti alloy plate material used as the molded body in Example 1, which is Ti-1 mass%CuO, exhibited biocompatibility equivalent to that of Ti.

[0068] As shown in Figure 13, the results of an antibacterial test using Staphylococcus aureus confirmed that using the Ti alloy sheet material of Example 1, which is Ti-1 mass%CuO, as the molded body, yielded an equivalent antibacterial effect compared to using the pure Ti sheet material produced by the L-PBF method and the known industrial pure Ti sheet material.

Claims

1. A biomedical implant containing element M selected from Cu, Ag, and Zn, and element X selected from O, C, and N, with the remainder being Ti and unavoidable impurities.

2. Step (A) involves mixing Ti powder with a powder of a compound containing element M selected from Cu, Ag, and Zn, and element X selected from O, C, and N. (B) A step of drying a mixture of Ti powder and the powder of the compound, A method for producing a Ti alloy, comprising the step (C) of adding thermal energy to the mixture after drying to melt the mixture.

3. The method for producing a Ti alloy according to claim 2, wherein in step (C), the mixture is melted by a laser powder bed fusion method.

4. The method for producing a Ti alloy according to claim 2 or 3, wherein the content of the compound in the mixture is 0.1% by mass or more and 30% by mass or less, when the mass of Ti is 100% by mass.

5. The method for producing a Ti alloy according to claim 2 or 3, wherein the compound is CuO.

6. A Ti alloy containing element M selected from Cu, Ag, and Zn, and element X selected from O, C, and N, with the remainder being Ti and unavoidable impurities.

7. The Ti alloy according to claim 6, wherein the mass of element M is 0.1% by mass or more and 20% by mass or less when the total mass of the Ti alloy is 100% by mass.

8. The Ti alloy according to claim 6 or 7, wherein the mass of element X when the total mass of the Ti alloy is 100% by mass is 0.01% by mass or more and 3.0% by mass or less.

9. The Ti alloy according to claim 6 or 7, wherein the element M is Cu and the element X is O.

10. It includes the α-phase and α'-phase of Ti, The Ti alloy according to claim 9, wherein Cu is solid-dissolved in at least the α' phase.

11. A molded body containing the Ti alloy described in claim 6 or 7.

Images