Titanium material, medical member, dental implant constituting member, and capsule for housing diamond sensor

Abstract

This titanium material contains 98.8 mass% or more of titanium. The density ρ g / cm3 of the titanium material and the percentage content c mass% of components other than titanium in the titanium material exhibits the relationship of formula I: ρ>0.007c+4.52. In formula I, c represents 0-1.2.

Description

Titanium materials, medical components, dental implant components, and capsules for storing diamond sensors

[0001] The present disclosure relates to titanium materials, medical components, dental implant components, and capsules for containing diamond sensors.

[0002] Titanium has a high specific strength and is therefore widely used in the aerospace and automotive industries. In addition, its excellent biocompatibility has led to increased demand for it as a biocompatible metal material for dental implants and other applications.

[0003] As shown in the temperature-pressure phase diagram of titanium in Figure 1, titanium exists in three phases: alpha titanium having an alpha phase (the phase designated as α in Figure 1), beta titanium having a beta phase (the phase designated as β in Figure 1), and omega titanium having an omega phase (the phase designated as ω in Figure 1). Alpha titanium is the stable phase at room temperature and pressure, and has a hexagonal close-packed (hcp) crystal structure. Beta titanium is the stable phase at higher temperatures, and has a body-centered cubic (bcc) crystal structure. Omega titanium is a metastable transition phase that occurs when alpha titanium is crystallized from beta titanium, and has a simple hexagonal crystal structure.

[0004] Patent Document 1 discloses a titanium material having high strength in which the α phase and the ω phase are mixed at room temperature and normal pressure.

[0005] Japanese Patent Application Laid-Open No. 2009-228053

[0006] The titanium material of the present disclosure is a titanium material containing titanium at 98.8 mass % or more, and has a density ρg / cm ３ The content c (mass %) of components other than titanium in the titanium material satisfies the relationship of the following formula I: ρ>0.007c+4.52 Formula I In the above formula I, c is 0 or more and 1.2 or less.

[0007] Figure 1 is a temperature-pressure phase diagram for titanium. Figure 2 is a coordinate system showing the relationship between the tensile strength σB and the fracture elongation δ of a conventional titanium material and the titanium material of embodiment 1. Figure 3 is a schematic cross-sectional view of a high-pressure cell of an ultra-high-pressure, high-temperature generator used in producing the titanium material of the present disclosure. Figure 4 is a coordinate system showing the relationship between the density ρ of the titanium material of each sample in the examples and the content c of components other than titanium in the titanium material.

[0008] [Problem to be Solved by the Present Disclosure] In recent years, as the applications of titanium materials have expanded, there has been a demand for titanium materials with higher strength.

[0009] The present disclosure aims to provide a titanium material having high strength.

[0010] [Advantages of the Present Disclosure] The titanium material of the present disclosure can have high strength.

[0011] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. (1) The titanium material of the present disclosure is a titanium material containing 98.8 mass % or more of titanium, and the density of the titanium material is ρg / cm ３ The content c (mass %) of components other than titanium in the titanium material satisfies the relationship of the following formula I: ρ>0.007c+4.52 Formula I In the above formula I, c is 0 or more and 1.2 or less.

[0012] The titanium material of the present disclosure can have high strength. In this disclosure, "the titanium material has high strength" means that the strength of the titanium material of the present disclosure is higher than the strength of a conventional titanium material having the same titanium content and in which the titanium is alpha titanium. In this disclosure, "strength" means tensile strength.

[0013] (2) In the above (1), the titanium material may contain 49 mass % or more of titanium having an omega-phase crystal structure, which allows the titanium material to have even higher strength.

[0014] (3) In the above (1) or (2), the tensile strength σB MPa and the breaking elongation δ% of the titanium material may have the relationship of the following formula II: σB≧1600−30δ Formula II In the above formula II, σB≧400 and δ≧20.

[0015] This allows the titanium material to have high strength and high ductility.

[0016] (4) In any one of (1) to (3) above, the average grain size of the crystal grains constituting the titanium material may be 1 μm or more and 1000 μm or less, thereby enabling the titanium material to have high strength and high ductility.

[0017] (5) In any one of (1) to (4) above, the titanium material may have a Vickers hardness of 200 Hv or more. This allows the titanium material to have high hardness.

[0018] (6) In any of the above (1) to (5), the heat-resistant temperature of the titanium material may be 100°C or higher. This allows the titanium material to maintain high strength even at high temperatures of 100°C or higher.

[0019] (7) In any one of the above (1) to (6), the volume of the titanium material is 0.001 mm ３ As a result, the titanium material has a sufficient size to be used as a biomedical metal material, and can be used for various purposes such as dental implant components and artificial joints. It can also be suitably used as a material for capsules containing diamond sensors.

[0020] (8) In any one of (1) to (7) above, the titanium material may contain at least one impurity element selected from the group consisting of hydrogen, carbon, nitrogen, oxygen, and iron, and the total content of the titanium and the impurity element in the titanium material may be 99.99 mass% or more, thereby enabling the titanium material to have excellent biocompatibility.

[0021] (9) In any of the above (1) to (8), in the volume-based cumulative particle size distribution of crystal grains constituting the titanium material, the ratio D90 / D10 of the cumulative 90% particle diameter D90 from the smaller diameter side to the cumulative 10% particle diameter D10 from the smaller diameter side may be 5 or more and 1000 or less. This homogenizes the strength and ductility of the titanium material, allowing the titanium material to have even higher strength and ductility.

[0022] (10) A medical device according to the present disclosure is a medical device containing any one of the titanium materials described above in (1) to (9). The medical device according to the present disclosure can have high strength.

[0023] (11) A dental implant component of the present disclosure is a dental implant component containing any one of the titanium materials described above in (1) to (9). The dental implant component of the present disclosure can have high strength.

[0024] (12) The capsule for storing a diamond sensor of the present disclosure is a capsule for storing a diamond sensor containing any one of the titanium materials (1) to (9) above. The capsule for storing a diamond sensor of the present disclosure can have high strength.

[0025] [Details of the embodiments of the present disclosure] Specific examples of the titanium material, medical device, dental implant component, and diamond sensor storage capsule of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been changed as appropriate for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0026] In the present disclosure, the notation in the form of "A to B" means the upper and lower limits of a range (i.e., A or more and B or less), and when no unit is specified for A and a unit is specified only for B, the units of A and B are the same.

[0027] In the present disclosure, when one or more numerical values ​​are recited as the lower limit and the upper limit of a numerical range, a combination of any one numerical value recited as the lower limit and any one numerical value recited as the upper limit is also considered to be disclosed. For example, when a1 or more, b1 or more, and c1 or more are recited as the lower limit and a2 or less, b2 or less, and c2 or less are recited as the upper limit, a1 or more and a2 or less, a1 or more and b2 or less, a1 or more and c2 or less, b1 or more and a2 or less, b1 or more and b2 or less, b1 or more and c2 or less, c1 or more and a2 or less, c1 or more and b2 or less, and c1 or more and c2 or less are considered to be disclosed.

[0028] [Embodiment 1: Titanium Material] A titanium material according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 1") is a titanium material containing 98.8 mass % or more of titanium, and has a density ρ (g / cm ３ ) and the content c (mass %) of components other than titanium in the titanium material satisfy the relationship of the following formula I: ρ>0.007c+4.52 Formula I In the above formula I, c is 0 or more and 1.2 or less.

[0029] The titanium material of embodiment 1 can have high strength. In formula I, the slope is 0.007. This indicates that as the content rate c of components other than titanium in the titanium material increases, the density of the titanium material tends to increase, and the strength of the titanium material tends to improve.

[0030] Density ρ (g / cm ３ ) and the content c (mass %) of components other than titanium in the titanium material can show the relationship of the following formula IA or IB: ρ > 0.007c + 4.536 Formula IA ρ > 0.007c + 4.552 Formula IB In the above formulas IA and IB, c is equal to or greater than 0 and equal to or less than 1.2. A titanium material that satisfies the above formula IA or IB can have even higher strength.

[0031] <Composition> The titanium material of embodiment 1 contains 98.8% or more by mass of titanium. From the viewpoint of improving biocompatibility, the lower limit of the titanium content of the titanium material may be 98.80% or more by mass, 98.90% or more by mass, 98.955% or more by mass, 98.96% or more by mass, 99.0% or more by mass, 99.20% or more by mass, 99.205% or more by mass, 99.30% or more by mass, 99.325% or more by mass, 99.40% or more by mass, 99.495% or more by mass, 99.99% or more by mass, or 99.999% or more by mass. The upper limit of the titanium content of the titanium material may be 100% or less by mass. The titanium material may also consist of 100% by mass of titanium. The titanium content of the titanium material may be 98.8% by mass or more and 100% by mass or less, 98.955% by mass or more and 100% by mass or less, 99.0% by mass or more and 100% by mass or less, 99.205% by mass or more and 100% by mass or less, 99.325% by mass or more and 100% by mass or less, 99.495% by mass or more and 100% by mass or less, or 99.999% by mass or more and 100% by mass or less.

[0032] The upper limit of the titanium content of the titanium material of embodiment 1 may be, for example, 99.9999% by mass or less, or 99.999% by mass or less, taking into account inevitable impurities. The titanium content of the titanium material may be 98.8% by mass to 99.9999% by mass, 98.955% by mass to 99.9999% by mass, 99.0% by mass to 99.9999% by mass, 99.205% by mass to 99.9999% by mass, 99.325% by mass to 99.9999% by mass, 99.495% by mass to 99.9999% by mass, or 99.9990% by mass to 99.9999% by mass.

[0033] The content c of components other than titanium in the titanium material of embodiment 1 is 0% by mass or more and 1.2% by mass or less. Examples of components other than titanium include common transition metal elements (e.g., scandium (Sc), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), hafnium (Hf), tantalum (Ta), tungsten (W), platinum (Pt), and gold (Au)), as well as inevitable impurities such as hydrogen (H), carbon (C), nitrogen (N), and oxygen (O).

[0034] In the present disclosure, the method for measuring the content c of components other than titanium in a titanium material is as follows: The titanium material is subjected to ICP (inductively coupled plasma atomic emission spectroscopy) to measure the total content c1 (mass %) of all metal elements other than titanium (Sc, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ag, Hf, Ta, W, Pt, Au, etc.); The titanium material is subjected to SIMS (secondary ion mass spectroscopy) to measure the total content c2 (mass %) of all elements other than metal elements (carbon (C), nitrogen (N), oxygen (O), hydrogen (H), etc.); In the present disclosure, the sum of total content c1 and total content c2 corresponds to the content c of components other than titanium in the titanium material.

[0035] In the present disclosure, the method for measuring the titanium content of a titanium material is to measure the content c of components other than titanium using the method described above, and then subtract the content c of components other than titanium from the titanium material, assuming the titanium material to be 100% by mass.

[0036] In embodiment 1, the titanium material contains 98.8% by mass or more of titanium, and the titanium material contains at least one impurity element selected from the group consisting of hydrogen, carbon, nitrogen, oxygen, and iron, and the total content of titanium and the impurity element in the titanium material may be 99.99% by mass or more. This means that the titanium material does not contain, or contains only trace amounts of, components harmful to living organisms, such as vanadium (V) and aluminum (Al), which are contained in conventional titanium alloys, and therefore has excellent biocompatibility.

[0037] The total content of titanium and the above impurity elements in the titanium material may be 99.99% by mass or more and 100% by mass or less, or 99.999% by mass or more and 100% by mass or less, or may be 100% by mass.

[0038] <Density ρ> The lower limit of the density ρ of the titanium material of embodiment 1 is 4.52 g / cm ３ and 4.536 g / cm ３ or more, 4.543 g / cm ３ or more, 4.544 g / cm ３ or more, or 4.552 g / cm ３ The upper limit of the density ρ of the titanium material is 4.58 g / cm ３ or less, 4.57 g / cm ３ or less, 4.56 g / cm ３ The density ρ of the titanium material may be 4.52 g / cm ３ Super 4.58g / cm ３ or less, 4.536 g / cm ３ More than 4.570g / cm ３ or less, or 4.552 g / cm ３ More than 4.560g / cm ３ The following is also acceptable.

[0039] In this disclosure, the density of a titanium material is measured as follows. The volume (gas pycnometer) and mass of the titanium material sample are measured by a dry gas displacement method using a Micromeritics dry automatic density meter (Accupyc II 1345 series). The density of the titanium material is calculated based on the obtained volume and mass. The displacement gas used in the gas pycnometer is helium, nitrogen, or other inert gas. An electronic balance is used for mass measurement, with an accuracy of at least five significant digits. It has been confirmed that the volume of the same sample measured using the pycnometer is measured at least 10 times, with almost no variance in the measurement results (e.g., within 0.02%) and almost no variance in the density calculated from the mass and volume (e.g., within 0.02%).

[0040] <Titanium Having an Omega Phase Crystal Structure> The titanium material of embodiment 1 can contain 49 mass % or more of titanium having an omega phase crystal structure, which allows the titanium material to have excellent strength and ductility.

[0041] The presence of omega titanium at room temperature and pressure has been confirmed in the manufacturing process of alpha pure titanium, which contains approximately 99% by mass or more of alpha titanium, by precipitation of trace amounts of nanoparticles in the alpha titanium phase. Omega titanium weakens alpha pure titanium. Therefore, it has been considered desirable to reduce the content of omega titanium in alpha pure titanium.

[0042] The inventors, based on an idea completely opposite to the conventional technical idea of ​​reducing the omega titanium content in alpha pure titanium, have produced a titanium material containing 49 mass% or more of omega titanium through trial and error. It has been confirmed that the titanium material containing 49 mass% or more of omega titanium has excellent strength and ductility.

[0043] From the viewpoint of improving strength and ductility, the lower limit of the content of titanium having an omega-phase crystal structure in the titanium material (hereinafter also referred to as "omega titanium content") may be 49% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 98.8% by mass or more, 98.955% by mass or more, 99% by mass or more, 99.2% by mass or more, 99.205% by mass or more, 99.325% by mass or more, 99.495% by mass or more, 99.5% by mass or more, or 99.999% by mass or more. The upper limit of the omega titanium content of the titanium material may be 100% by mass or less. The titanium material may also consist of 100% by mass of omega titanium. The omega titanium content of the titanium material may be 49% by mass or more and 100% by mass or less, 50% by mass or more and 100% by mass or less, 55% by mass or more and 100% by mass or less, 60% by mass or more and 100% by mass or less, 65% by mass or more and 100% by mass or less, 70% by mass or more and 100% by mass or less, 75% by mass or more and 100% by mass or less, 80% by mass or more and 100% by mass or less, 85% by mass or more and 100% by mass or less, 90% by mass or less and 100% by mass or less, 95% by mass or less and 100% by mass or less, 98.8% by mass or more and 100% by mass or less, 99% by mass or more and 100% by mass or less, 99.2% by mass or more and 100% by mass or less, or 99.999% by mass or more and 100% by mass or less.

[0044] The upper limit of the omega titanium content of the titanium material of embodiment 1 can be, for example, 99.9999 mass% or less, taking into account inevitable impurities. The omega titanium content of the titanium material may be 49 mass% or more and 99.9999 mass% or less, 50 mass% or more and 99.9999 mass% or less, 55 mass% or more and 99.9999 mass% or less, 60 mass% or more and 99.9999 mass% or less, 65 mass% or more and 99.9999 mass% or less, 70 mass% or more and 99.9999 mass% or less, 75 mass% or more and 99.9999 mass% or less, 80 mass% or more and 99.9999 mass% or less. 9999% by mass or less, 85% by mass or more and 99.9999% by mass or less, 90% by mass or more and 99.9999% by mass or less, 95% by mass or more and 99.9999% by mass or less, 98.8% by mass or more and 99.9999% by mass or less, 99% by mass or more and 99.9999% by mass or less, 99.2% by mass or more and 99.9999% by mass or less, or 99.9990% by mass or more and 99.9999% by mass or less.

[0045] The titanium material of embodiment 1 may contain one or both of alpha titanium and beta titanium in addition to omega titanium, as long as the effects of the present disclosure are exhibited. The total content of alpha titanium and beta titanium in the titanium material can be calculated by subtracting the content of omega titanium from the content of titanium in the titanium material.

[0046] In the titanium material of embodiment 1, the mass percentage of omega titanium to the total of alpha titanium, beta titanium, and omega titanium may be 50% or more and 100% or less, 55% or more and 100% or less, 60% or more and 100% or less, 65% or more and 100% or less, 70% or more and 100% or less, 75% or more and 100% or less, 80% or more and 100% or less, 85% or more and 100% or less, 90% or less and 100% or less, 95% or less and 100% or less, 98.8% or more and 100% or less, 99% or more and 100% or less, 99.2% or more and 100% or less, 99.999% or more and 100% or less, or even 100%. The percentage by weight of omega titanium relative to the sum of alpha titanium, beta titanium and omega titanium refers to the percentage by weight of titanium of omega titanium.

[0047] The omega titanium content (mass%) of a titanium material is measured using the following procedure. First, the content c of components other than titanium in the titanium material is measured using ICP analysis and SIMS analysis. The titanium material is set to 100 mass%, and the content c of components other than titanium is subtracted from this to obtain the titanium content (mass%) of the titanium material. Next, X-ray diffraction measurement is performed on the titanium material to obtain an X-ray diffraction spectrum.

[0048] An example of an apparatus used for X-ray diffraction measurement is the "MiniFlex" (trademark) manufactured by Rigaku Corporation. The conditions for X-ray diffraction measurement are as follows: <X-ray diffraction measurement conditions> Characteristic X-ray: Cu-Kα (wavelength 1.54 Å) Filter: Multilayer mirror Optical system: Focusing method X-ray diffraction method: θ-2θ method Temperature during measurement: 25°C

[0049] In the obtained X-ray diffraction spectrum, the intensities of omega titanium, alpha titanium, and beta titanium are measured. The intensity Iω of omega titanium is the maximum intensity in the range of 2θ = 38.8° to 39.2°. The intensity Iα of alpha titanium is the maximum intensity in the range of 2θ = 39.4° to 40.6°. The intensity Iβ of beta titanium is the maximum intensity in the range of 2θ = 38.2° to 38.7°. The percentage (% by mass) of titanium and omega titanium in the titanium material is obtained by calculating the ratio Iω / (Iω + Iα + Iβ) of the intensity Iω to the total of the intensities Iω, Iα, and Iβ. The content (% by mass) of omega titanium in the titanium material is calculated based on the titanium content (% by mass) of the titanium material and the percentage (% by mass) of omega titanium in the titanium material.

[0050] <Relationship Between Tensile Strength σB MPa and Elongation at Break δ%> In the titanium material of embodiment 1, the tensile strength σB MPa and elongation at break δ% of the titanium material can have the relationship of the following formula II: σB≧1600−30δ Formula II In the above formula II, σB≧400 and δ≧20.

[0051] Titanium materials that exhibit the relationship of Formula II above will be explained using Figure 2. Figure 2 is a coordinate system showing the relationship between tensile strength σB and fracture elongation δ of titanium materials. In the coordinate system of Figure 2, the X-axis represents tensile strength σB (MPa), and the Y-axis represents fracture elongation δ (%). Tensile strength is an index of a material's strength, with a higher value indicating higher strength. Fracture elongation is an index of a material's ductility, with a higher value indicating higher ductility. In Figure 2, conventional titanium materials are shown in JIS-1 to JIS-4. These tensile strength and fracture elongation data were compiled with reference to Figure 1 in Hideki Fujii and Takashi Maeda (2013), "Nippon Steel & Sumitomo Metal Corporation's Proprietary Titanium Alloys," Nippon Steel & Sumitomo Metal Techniques No. 396, pp. 16-22.

[0052] JIS-1 to JIS-4 refer to commercially pure titanium as described in JIS H 4600:2012 "Titanium and Titanium Alloys - Plate and Strip." Specifically, JIS-1 refers to JIS H 4600 Type 1, JIS-2 refers to JIS H 4600 Type 2, JIS-3 refers to JIS H 4600 Type 3, and JIS-4 refers to JIS H 4600 Type 4. JIS-1 to JIS-4 have a titanium content of approximately 99% by mass or more and an alpha-phase crystal structure. Hereinafter, pure titanium with an alpha-phase crystal structure will also be referred to as alpha-pure titanium.

[0053] In Figure 2, the region that satisfies the relationship of formula II above is the shaded region. The shaded region has high ductility, with a fracture elongation of 20% or more, and high strength, with a tensile strength of 400 MPa or more. Titanium materials that satisfy the relationship of formula II above have high strength and high ductility. Alpha pure titanium, a conventional titanium material, has high fracture elongation (hereinafter also referred to as ductility), but low tensile strength (hereinafter also referred to as strength), and does not satisfy the relationship of formula II above.

[0054] The tensile strength σB (MPa) and elongation at break δ% of a titanium material can show the relationship of the following formula II-A or II-B: σB>1875-30δ Formula II-A σB>1900-30δ Formula II-B In the above formulas II-A and II-B, σB≧400 and δ≧20. A titanium material that satisfies the relationship of formula II-A or II-B can have even higher strength and ductility.

[0055] <Tensile Strength σB> The lower limit of the tensile strength σB of the titanium material of embodiment 1 can be 400 MPa or more. From the viewpoint of ensuring excellent strength, the lower limit of the tensile strength σB of the titanium material may be 500 MPa or more, 600 MPa or more, or 800 MPa or more. The upper limit of the tensile strength σB of the titanium material is not particularly limited, but can be, for example, less than 1550 MPa. The tensile strength σB of the titanium material may be 400 MPa or more and less than 1550 MPa, 500 MPa or more and less than 1550 MPa, 600 MPa or more and less than 1550 MPa, or 800 MPa or more and less than 1550 MPa.

[0056] The tensile strength σB of titanium material is measured in accordance with JIS Z 2241:2011 "Method of tensile testing for metallic materials." The test temperature is 23°C ± 5°C.

[0057] <Fracture elongation δ> The fracture elongation δ of the titanium material of embodiment 1 can be 20% or more. From the viewpoint of ensuring excellent ductility, the lower limit of the fracture elongation δ of the titanium material may be 25% or more, 30% or more, or 35% or more. The upper limit of the fracture elongation δ of the titanium material may be, for example, 50% or less, or 45% or less. The fracture elongation δ of the titanium material may be 20% or more and 50% or less, 25% or more and 50% or less, 30% or more and 50% or less, 35% or more and 50% or less, 20% or more and 45% or less, 25% or more and 45% or less, or 30% or more and 45% or less.

[0058] The fracture elongation δ of the titanium material is measured in accordance with JIS Z 2241:2011 "Method of tensile testing for metallic materials." The test temperature is 23°C ± 5°C.

[0059] <Average grain size> The average grain size of the crystal grains constituting the titanium material of embodiment 1 (hereinafter also referred to as "average grain size of the titanium material") can be 1 μm or more and 1000 μm or less, which further improves the strength and ductility of the titanium material.

[0060] From the viewpoint of improving strength, the lower limit of the average particle size of the titanium material may be 1 μm or more, 3 μm or more, 5 μm or more, 10 μm or more, or 20 μm or more. From the viewpoint of ensuring excellent strength, the upper limit of the average particle size of the titanium material may be 1,000 μm or less, 500 μm or less, 200 μm or less, 100 μm or less, or 50 μm or less. The average particle size of the titanium material may be 1 μm or more to 1,000 μm or less, 3 μm or more to 500 μm or less, 5 μm or more to 200 μm or less, 10 μm or more to 100 μm or less, 10 μm or more to 50 μm or less, or 20 μm or more to 50 μm or less.

[0061] In this disclosure, the average grain size of the titanium material is measured by a cutting method. The specific measuring method is as follows: The surface of the titanium material is polished with SiC polishing paper and Al ２ O ３ The surface is polished with a lapping film, and the polished surface is photographed using an optical microscope at a magnification of 100 times to obtain an optical microscope image.

[0062] A circle with a diameter of 50 mm is drawn on the optical microscope image, and eight straight lines are drawn radially from the center of the circle to the periphery of the circle, and the number of grain boundaries that the lines cross within the circle is counted. The average intercept length is calculated by dividing the length of the line by the number of crossings, and the average intercept length is multiplied by 1.128, a conversion coefficient to two-dimensional particle size, to obtain the average particle size.

[0063] The above measurement is performed at three locations on one measurement sample, and the average value of the average particle diameters at the three locations is defined as the average particle diameter of the titanium material in this disclosure.

[0064] As far as the applicant has measured, it has been confirmed that there is almost no variation in the measurement results, even if the average particle size of titanium material is measured multiple times at different measurement locations, as long as the measurements are performed on the same sample.

[0065] From the viewpoint of homogenizing strength and ductility, it is preferable that the grain size of the crystal grains constituting the titanium material have small variations. In the volume-based cumulative grain size distribution of the crystal grains constituting titanium, the ratio D90 / D10 of the cumulative 90% particle diameter D90 from the small diameter side to the cumulative 10% particle diameter D10 from the small diameter side may be 5 or more and 1000 or less, or may be 10 or more and 1000 or less. A smaller value of D90 / D10 indicates smaller variations in the grain size of the crystal grains.

[0066] The particle size of each crystal grain for calculating the D90 / D10 is determined by measuring the equivalent circle diameter of each crystal grain by image processing using commercially available image analysis software on an optical microscope image taken under the same conditions as the above-mentioned cutting method. A measurement field of view of 50 mm x 50 mm is set in the optical microscope image, and a volume-based cumulative particle size distribution is created based on all crystal grains observed in the measurement field. D90 / D10 is calculated based on this cumulative particle size distribution.

[0067] <Vickers Hardness> The Vickers hardness of the titanium material of embodiment 1 can be set to 200 Hv or more. This gives the titanium material excellent hardness and improved wear resistance.

[0068] The lower limit of the Vickers hardness of the titanium material may be 200 Hv or more, or 220 Hv or more, from the viewpoint of ensuring excellent hardness. The upper limit of the Vickers hardness of the titanium material is preferably as high as possible, so is not particularly limited, but may be, for example, 400 Hv or less. The Vickers hardness of the titanium material may be 200 Hv or more and 400 Hv or less, or 220 Hv or more and 400 Hv or less.

[0069] The Vickers hardness of titanium materials is measured in accordance with JIS Z 2244:2009 "Vickers hardness test - Test method." The test temperature is 23°C ± 5°C.

[0070] As far as the applicant has measured, it has been confirmed that there is almost no variation in the measurement results when measuring the Vickers hardness of titanium material multiple times by changing the measurement location, as long as the measurements are made on the same sample.

[0071] <Heat Resistance Temperature> The heat resistance temperature of the titanium material of embodiment 1 can be set to 100° C. or higher. This allows the titanium material to maintain excellent strength even at high temperatures of 100° C. or higher.

[0072] The lower limit of the heat-resistant temperature of the titanium material of embodiment 1 may be 100°C or higher, 120°C or higher, or 140°C or higher, from the viewpoint of ensuring excellent strength. The upper limit of the heat-resistant temperature of the titanium material is not particularly limited, as a higher limit is preferable, but it may be, for example, 190°C or lower. The heat-resistant temperature of the titanium material may be 100°C or higher and 190°C or lower, 120°C or higher and 190°C or lower, or 140°C or higher and 190°C or lower.

[0073] The heat resistance temperature of a titanium material is measured by X-ray diffraction analysis, by comparing the X-ray diffraction pattern at 25° C. with the X-ray diffraction pattern at a predetermined temperature. The specific measurement method is as follows.

[0074] The surface of the titanium material is polished to prepare a measurement sample. Using an X-ray diffractometer, the measurement sample is irradiated with X-rays under the following measurement conditions to obtain an X-ray diffraction pattern. The measurement temperature is selected to be 25°C and multiple temperatures above 25°C, and an X-ray diffraction pattern is obtained at each temperature.

[0075] <<X-ray diffraction measurement conditions>> Characteristic X-ray: Cu-Kα (wavelength 1.54 Å) Filter: Multilayer mirror Optical system: Concentration method X-ray diffraction method: θ-2θ method

[0076] The X-ray diffraction pattern at 25°C is compared with the X-ray diffraction pattern at a predetermined temperature above 25°C (hereinafter also referred to as "predetermined temperature"), and if the shapes of both X-ray diffraction patterns match, the measurement sample is judged to have heat resistance and maintain its crystalline structure at the predetermined temperature. Here, "the two X-ray diffraction patterns match" is confirmed by the fact that all the diffraction peak positions match and the order of the intensities of each diffraction peak also matches.

[0077] The X-ray diffraction measurement is performed by increasing the temperature condition until the X-ray diffraction pattern at a predetermined temperature above 25° C. becomes different in shape from the X-ray diffraction pattern at 25° C. Among the multiple X-ray diffraction patterns obtained, the X-ray diffraction pattern at the highest temperature that matches the X-ray diffraction pattern at 25° C. is identified. The highest temperature is determined to be the heat-resistant temperature of the measurement sample.

[0078] <Volume> The volume of the titanium material of embodiment 1 is 0.001 mm ３ The titanium material has a size sufficient for use as a biomedical metal material, and can be used in a variety of applications, such as dental implant components and artificial joints. It can also be suitably used as a material for capsules containing diamond sensors.

[0079] The lower limit of the volume of titanium material is 0.001 mm ３ More than 0.01 mm is acceptable. ３ More than 0.1 mm is acceptable. ３ More than 1 mm is also acceptable. ３ More than 10 mm is also acceptable. ３ It may be more than 100 mm, or ３ The upper limit of the volume of the titanium material is preferably as large as possible, but is not particularly limited. For example, it may be 100,000 mm ３ Preferably, the volume of the titanium material is less than 0.001 mm ３ More than 100,000 mm ３ It may be less than 10 mm ３ More than 100,000 mm ３ It may be less than 100 mm, or ３ More than 100,000 mm ３ The volume of the titanium material is measured by Archimedes' method.

[0080] <0.2% Yield Strength in Tensile Test> The 0.2% yield strength in a tensile test of the titanium material of embodiment 1 can be made to exceed 180 MPa, which further improves the strength.

[0081] From the viewpoint of ensuring excellent strength, the lower limit of the 0.2% yield strength in a tensile test of a titanium material may be 250 MPa or more, 400 MPa or more, or 550 MPa or more. The upper limit of the 0.2% yield strength in a tensile test of a titanium material is preferably as large as possible, and is therefore not particularly limited.

[0082] Measurement of 0.2% yield strength in tensile tests of titanium materials is carried out in accordance with JIS Z 2241:2011 "Method of tensile testing of metallic materials." The test temperature is 23°C ± 5°C.

[0083] <0.2% Yield Strength in Compression Test> The 0.2% yield strength in a compression test of the titanium material of embodiment 1 can be set to 570 MPa or more, which further improves the strength.

[0084] The lower limit of the 0.2% yield strength in a compression test of a titanium material may be 600 MPa or more, 700 MPa or more, or 800 MPa or more, from the viewpoint of ensuring excellent strength. The upper limit of the 0.2% yield strength in a compression test of a titanium material is preferably higher, so is not particularly limited, but can be, for example, 5000 MPa or less. The 0.2% yield strength in a compression test of a titanium material may be 570 MPa or more and 5000 MPa or less, 600 MPa or more and 5000 MPa or less, 700 MPa or more and 5000 MPa or less, or 800 MPa or more and 5000 MPa or less.

[0085] Measurement of the 0.2% yield strength in a compression test of titanium material is carried out in accordance with JIS R 1608:2003 "Test method for compressive strength of fine ceramics." The test temperature is 23°C ± 5°C.

[0086] [Embodiment 2: Medical Device] A medical device according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 2") is a medical device containing the titanium material described in Embodiment 1. The medical device of Embodiment 2 can have high strength. Examples of medical devices include dental implant components, artificial joints, and housings and components for implantable devices.

[0087] [Embodiment 3: Dental implant component] A dental implant component according to one embodiment (hereinafter also referred to as "Embodiment 3") of the present disclosure is a dental implant component comprising the titanium material described in Embodiment 1. The dental implant component of Embodiment 3 can have high strength.

[0088] [Embodiment 4: Capsule for storing a diamond sensor] A capsule for storing a diamond sensor according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 4") is a capsule for storing a diamond sensor that includes the titanium material described in Embodiment 1. The titanium material of Embodiment 1 has high strength, so it can be suitably used as a material for a capsule for storing a diamond sensor.

[0089] [Embodiment 5: Method for Producing Titanium Material] The method for producing the titanium material of embodiment 1 (hereinafter also referred to as "embodiment 5") will be described below.

[0090] To better understand the method for producing a titanium material according to the fifth embodiment, a conventional method for producing a titanium material will be described.

[0091] In Patent Document 1, titanium materials are produced by subjecting pure titanium, α-titanium alloys, and α+β-titanium alloys to plastic processing with a processing strain of 0.5 or more under a pressure of 1.5 GPa or more. The grain size of the crystal grains that make up the titanium material in Patent Document 1 is small, on the order of several hundred nanometers, and is therefore presumably low in ductility. Furthermore, because the titanium material is produced while applying processing strain to the raw material, a strain gradient exists between the center and edges of the titanium material, making it heterogeneous and unsuitable for measuring mechanical properties such as tensile strength.

[0092] As a result of extensive research, the present inventors have discovered a new method for producing a titanium material having high strength according to the present disclosure. The method for producing a titanium material according to a fifth embodiment will be described in detail below.

[0093] <Ultra-high-temperature, high-pressure generator> The ultra-high-pressure, high-temperature generator used in the production of titanium material in embodiment 5 will be described with reference to Figure 3. Figure 3 is a schematic cross-sectional view of a high-pressure cell of the ultra-high-pressure, high-temperature generator used in embodiment 5. The high-pressure cell 10 comprises a pressure medium 1 having a regular octahedron shape, a sample container 2 placed inside the pressure medium 1, and a heating element 3 placed around the sample container 2. The sample container 2 is made of hexagonal boron nitride. The heating element 3 is made of graphite. A raw material 4 is sealed inside the sample container 2. The maximum load of the ultra-high-pressure, high-temperature generator used in embodiment 5 is, for example, 2,800 tons.

[0094] <Preparation of Raw Material> Conventional alpha pure titanium containing at least 98.8 mass% titanium is prepared as the raw material. The titanium in alpha pure titanium is alpha titanium having an alpha phase crystal structure.

[0095] <High-Pressure, High-Temperature Treatment> The above raw materials are placed in a sample container made of hexagonal boron nitride polycrystalline material, and pressurized to 5 GPa at room temperature using an ultra-high-pressure, high-temperature generator, and then heated to 300°C. The pressure is then further increased to 9-11 GPa, and the material is heated to 500-700°C and maintained at this temperature for 45-60 minutes. This produces the titanium material of the present disclosure.

[0096] In the manufacturing method of the fifth embodiment, the synthesis pressure is 9 GPa to 11 GPa, and the maximum load of the manufacturing apparatus is 2800 tons. For example, the diameter is 10 mm, the height is 6 mm, and the volume is 471 mm. ３ It is possible to fabricate large cylindrical titanium materials as described above. These titanium materials have a sufficient diameter to fabricate test pieces for tensile testing.

[0097] In addition, "Sawahata et al. (2018), Synthesis of Single-Phase Polycrystalline ω-Ti and ω-Zr Under High Pressure and Evaluation of Their Mechanical Properties, Science and Technology of High Pressure, Vol. 28, Special Issue" (hereinafter also referred to as "Reference 1") and "Sawahata et al. (2019), Synthesis of Single-Phase Polycrystalline ω-Ti Under High Pressure and Evaluation of Their Bending Properties, Science and Technology of High Pressure, Vol. 29, Special Issue, 93" (hereinafter also referred to as "Reference 2") disclose that ω-Ti was produced by treating commercially available α-Ti at 12 GPa and 400°C for 3 hours using a multi-anvil high-pressure apparatus (maximum load 1000 tons). References 1 and 2 use lanthanum chromite oxide (LaCr ２ O ３ , thermal conductivity: 5 W / (m·K) or less), and magnesia (MgO: 60 W / (m·K)) was used as the sample container. These materials have low thermal conductivity, so temperature gradients tend to occur around the raw materials during high-pressure, high-temperature processing. Furthermore, these materials have high hardness, so pressure gradients tend to occur. Therefore, it is presumed that the grain size of the crystal grains in the obtained titanium material is likely to vary. From the above, it is presumed that the ω-Ti produced in References 1 and 2 has lower strength than the titanium material of the present disclosure.

[0098] Furthermore, the titanium materials obtained in References 1 and 2 are small (diameter 4 mm, height 3 mm, volume 37.7 mm). ３ It was impossible to prepare test pieces for measuring mechanical properties such as tensile strength (cylindrical shape). The manufacturing conditions of References 1 and 2 used a pressure of 12 GPa, making it difficult to enlarge the titanium material.

[0099] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0100] [Samples 1 to 7] <Production of Titanium Materials> Alpha pure titanium having the composition shown in the "Raw Material Composition" column in Table 1 was prepared as the raw material for each sample. The titanium contained in the raw material for each sample was alpha titanium (α-Ti).

[0101] The raw materials for each sample were placed in a sample container made of hexagonal boron nitride polycrystal, and pressurized to 5 GPa at room temperature using a multi-anvil ultra-high pressure, high temperature generator (Voggenreiter "mavo press LPR 1000-400 / 50", graphite heating element, maximum load 2800 tons), and then heated to 300°C. The sample was then further pressurized to the pressure listed in the "Pressure" column of Table 1, heated to the temperature listed in the "Temperature" column of Table 1, and held for the time listed in the "Holding time" column of Table 1 to obtain a titanium material. The size of the obtained titanium material was 10 mm in diameter, 6 mm in height, and 471 mm in volume. ３ It was cylindrical.

[0102] [Samples 101 to 107] Samples 101 to 107 correspond to alpha pure titanium, which is the raw material for Samples 1 to 7, respectively. Sample 102 corresponds to JIS-1, Sample 103 corresponds to JIS-2, Sample 104 corresponds to JIS-3, and Samples 105 and 107 correspond to JIS-4. Samples 101 and 106 were prepared specifically for this example. For Sample 101, the total of the raw materials is 100.0001 mass%, but this is due to rounding.

[0103]

[0104] <Evaluation> For each sample of titanium material, the titanium (Ti) content, the mass-based percentage of omega titanium (ω-Ti / Ti) of titanium (shown in Table 2 under the column "ω-Ti / Ti"), the content c of components other than titanium in the titanium material, the type of impurity element, the total content of titanium and impurity elements in the titanium material (total content of Ti and impurity elements), density ρ, tensile strength σB, elongation at break δ, the average grain size of the crystal grains constituting the titanium material, D90 / D10, Vickers hardness, heat-resistant temperature (only for Samples 1 to 7), volume, 0.2% proof stress in a tensile test, and 0.2% proof stress in a compression test were measured. The measurement methods for each measurement item were as described in Example 1. The results are shown in Tables 2 to 4.

[0105] Each sample of titanium material was checked to see if it satisfied the relationship of the following formula I: ρ>0.007c+4.52 Formula I In the above formula I, c is 0 or more and 1.2 or less.

[0106] The density ρ (g / cm ３ The relationship between the content c (mass%) of components other than titanium in the titanium material and the content c (mass%) of components other than titanium in the titanium material is shown in the coordinate system of Figure 4. In the coordinate system of Figure 4, the X axis represents the content c (mass%) of components other than titanium, and the Y axis represents the density ρ (g / cm ３ In FIG. 4, the region showing the relationship of the above formula I is the region indicated by diagonal lines.

[0107] It is confirmed that the titanium materials of Samples 1 to 7 satisfy the relationship of Formula I, while the alpha pure titanium of Samples 101 to 107 do not satisfy the relationship of Formula I.

[0108] Each sample of titanium material was checked to see if it satisfied the relationship of the following formula II: σB≧1600−30δ Formula II In the above formula II, σB≧400 and δ≧20.

[0109] In the "Formula I" column of Table 2, "Yes" indicates that the relationship of Formula I is satisfied, and "No" indicates that the relationship of Formula I is not satisfied. In the "Formula II" column of Table 3, "Yes" indicates that the relationship of Formula II is satisfied, and "No" indicates that the relationship of Formula II is not satisfied.

[0110]

[0111]

[0112]

[0113] <Discussion> The titanium materials of Samples 1 to 7 correspond to Examples, and the alpha pure titanium of Samples 101 to 107 correspond to Comparative Examples.

[0114] Sample 1 and Sample 101 have the same titanium content. It was confirmed that Sample 1 had higher strength (tensile strength) than Sample 101.

[0115] Sample 2 and Sample 102 have the same titanium content. It was confirmed that Sample 2 had higher strength (tensile strength) than Sample 102.

[0116] Sample 3 and Sample 103 have the same titanium content. It was confirmed that Sample 3 had higher strength (tensile strength) than Sample 103.

[0117] Sample 4 and Sample 104 have the same titanium content. It was confirmed that Sample 4 had higher strength (tensile strength) than Sample 104.

[0118] Sample 5 and Sample 105 have the same titanium content. Sample 5 was confirmed to have higher strength (tensile strength) than Sample 1051.

[0119] Sample 6 and Sample 106 have the same titanium content. It was confirmed that Sample 6 had higher strength (tensile strength) than Sample 106.

[0120] Sample 7 and Sample 107 have the same titanium content. It was confirmed that Sample 7 had higher strength (tensile strength) than Sample 107.

[0121] From the above results, it was confirmed that the strength of the titanium materials of Samples 1 to 7 was higher than the strength of titanium materials with the same titanium content but in which the titanium was alpha titanium, and that the titanium materials of Samples 1 to 7 had high strength.

[0122] Although the embodiments and examples of the present disclosure have been described above, it is intended from the beginning that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments and examples, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0123] 1 Pressure medium, 2 Sample container, 3 Heating element, 4 Raw material, 10 High-pressure cell

Claims

1. A titanium material containing 98.8% by mass or more of titanium, The density ρg / cm of the titanium material ３ and the content c mass % of the component other than titanium in the titanium material satisfies the relationship of the following formula I: ρ>0.007c+4.52 Formula I A titanium material, wherein in the above formula I, c is 0 or more and 1.2 or less.

2. The titanium material according to claim 1 , wherein the titanium material contains 49% by mass or more of titanium having an omega phase crystal structure.

3. The tensile strength σB MPa of the titanium material and the breaking elongation δ% of the titanium material are related by the following formula II: σB≧1600−30δ Formula II 3. The titanium material according to claim 1 or 2, wherein, in the above formula II, σB≧400 and δ≧20.

4. 3. The titanium material according to claim 1, wherein the average grain size of the crystal grains constituting the titanium material is 1 μm or more and 1000 μm or less.

5. 3. The titanium material according to claim 1, wherein the titanium material has a Vickers hardness of 200 Hv or more.

6. 3. The titanium material according to claim 1, wherein the titanium material has a heat resistance temperature of 100°C or higher.

7. The volume of the titanium material is 0.001 mm ３ The titanium material according to claim 1 or 2, wherein

8. the titanium material contains at least one impurity element selected from the group consisting of hydrogen, carbon, nitrogen, oxygen, and iron; 3. The titanium material according to claim 1, wherein the total content of the titanium and the impurity elements in the titanium material is 99.99 mass% or more.

9. 3. The titanium material according to claim 1, wherein a ratio D90 / D10 of a cumulative 90% particle diameter D90 from the smaller diameter side to a cumulative 10% particle diameter D10 from the smaller diameter side in a volume-based cumulative particle size distribution of crystal grains constituting the titanium material is 5 or more and 1,000 or less.

10. A medical device comprising the titanium material according to claim 1 or 2.

11. A dental implant component comprising the titanium material of claim 1 or claim 2.

12. A capsule for storing a diamond sensor, comprising the titanium material according to claim 1 or 2.