JP2000087160A - Titanium alloy for living body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a titanium alloy for a living body excellent in mechanical characteristics and restraining metallic elements from eluting as ions when the alloy is used in a living body. SOLUTION: This titanium alloy has a compsn. consisting of, by weight, 4.0-7.0% Al, 8.0-18.0% Ta, one or more selected from <=1% (Nb+Mo), <=1% (Zr+Sn), <=0.2% Si, <=0.2% O and <=0.1% (N+C) and the balance substantially Ti.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is suitable as a dental material such as an artificial tooth root and a tooth bed, an artificial bone material such as an artificial knee joint, a medical tool such as surgical tweezers and clips, and other biological materials. The present invention relates to a titanium alloy for living bodies.

[0002]

2. Description of the Related Art
As a dental alloy, gold, silver, palladium, nickel chromium alloy or the like is used. Recently, Ti is also excellent in corrosion resistance and has good compatibility with a living body, so as an artificial bone material such as an artificial knee joint, or It is used as a crown, an inlay and the like, or as a dental material for implants such as artificial roots and tooth beds, and other biological materials.

[0003] By the way, for example, most of Ti currently used for dentistry is generally called commercial pure Ti (CP-Ti). Is not enough.

[0004] According to JIS H 4600, Ti is classified into four types according to the content of impurities. However, the four types having the highest content of impurities and the highest strength have a tensile strength of about 500 MPa, and are used for dental purposes. It is not sufficiently strong to be used for all prostheses, and is not enough to be used as a dental material or other biological material subjected to large cyclic stress.

[0005] Under such circumstances, the use of a Ti alloy (titanium alloy) having a higher strength than Ti as a biomaterial such as a dental material has been studied. Here, Ti-6Al-4V is widely known as a Ti alloy, and is also used as a biomaterial including artificial joints. However, in this Ti-6Al-4V alloy, it has been reported that V as an alloying element has cytotoxicity, and there is a concern about the effect on human bodies.

Therefore, as an alternative to the Ti-6Al-4V alloy, there has been proposed a Ti-6Al-7Nb alloy in which V is replaced by Nb which is a homologous element. This Ti-6Al-7Nb alloy has a tensile strength of Ti-
Although slightly inferior to 6Al-4V alloy, it is sufficiently large compared to pure Ti, and can be cast in a casting system for Ti, and has corrosion resistance of Ti and Ti-6Al-4V.
As good as or better than alloys.

In the case of a material used in a living body, if a metal element dissolves in the living body as an ion, the influence on the human body is concerned, and the elution of the element deteriorates the characteristics of the material in the living body and causes corrosion. It also causes fatigue.

[0008]

In this respect, the above Ti-6A
Although 1-7Nb can be said to be a material excellent in the elution resistance of metal ions (less elution), the present inventor conducted a study to find a more excellent Ti alloy for a living body.
The following Ti alloys for living body were developed.

That is, the Ti alloy for living body of the present invention contains 4.0 to 7.0% of Al and 8.0 to 18.0% of Ta by weight, and further contains (Nb + Mo), (Zr + Sn), Si,
O, (N + C), one or more of Nb + M
o: ≦ 1.0%, Zr + Sn: ≦ 1.0%, Si: ≦
0.2%, O: ≦ 0.2%, N + C: ≦ 0.1%, with the balance substantially consisting of Ti.

[0010]

Operation and Effect of the Invention As described above, the Ti alloy of the present invention
Is the same periodicity table V in place of V as an alloying element _aGroup element
Is added, and (Nb + Mo), (Zr
+ Sn), any one or two of Si, O, (N + C)
The above is contained as a strengthening element. Where T
a is a metal having better corrosion resistance than Ti,
The compatibility is equal to or higher than that of Ti.

In the present invention, instead of V and Nb,
The addition of Ta, which is a homologous element, was aimed at obtaining a Ti alloy. When the mechanical properties and the degree of metal ion elution of the obtained alloy were examined, the tensile strength was not inferior to that of Ti-6Al-4V, and the elongation was superior to that of Ti-6Al-4V. In particular, the elution of metal ions (Ti ions) is T
It was less than i-6Al-4V and Ti-6Al-7Nb, and had higher safety and better mechanical properties than Ti-6Al-7Nb.

The inventor of the present invention has made efforts to further improve the mechanical properties of (Nb + Mo), (Zr + Sn), Si,
When one or more of O and (N + C) are used as the strengthening element, the tensile strength is further increased while suppressing the elution of Ti ions to a low level and maintaining the elongation property at a high level of Ti-6Al-4V or higher. It can be strengthened and its strength characteristics
It was confirmed that it could be increased to a level close to -6Al-4V. Such a Ti alloy of the present invention is promising as a material superior to that conventionally provided as a biomaterial.

Next, the reasons for limiting each chemical component in the present invention will be described in detail. Al: 4.0 to 7.0 Al is an element effective for strengthening the α phase, and the alloy strength can be increased by adding 4.0% or more. 7.0
%, The α2 (Ti ₃ Al) phase is precipitated, which causes a decrease in ductility. Here, in the present invention, the upper limit is set to 7.0%.

Ta: 8.0-18.0% Ta has the function of suppressing the elution of Ti ions, and is also an element stabilizing the β phase. It is effective in improving the heat treatment property and improving the alloy strength. is there. For that purpose, it is necessary to add 8.0% or more. On the other hand, if it is added in excess of 18.0%, the productivity decreases. Specifically, because of the high melting point metal, it becomes difficult to dissolve as the amount of addition increases. Therefore, in the present invention, the upper limit is set to 18.0%.

Nb + Mo: ≦ 1.0% These Nb and Mo are β-stabilizing elements like Ta,
It is possible to add one or two of Mo and Nb in such a manner that Ta is partially substituted. However, if added in excess of 1.0%, the elution resistance decreases, so the upper limit is set to 1.0%.
And The desirable content of Nb + Mo is 0.1% or more.

Zr + Sn: ≦ 1.0 Zr and Sn are neutral elements effective for strengthening both α and β. Therefore, in the present invention, it is also effective to add one or two of them. However, if the content exceeds 1.0%, the elution resistance decreases, so the upper limit is made 1.0%. The desirable content of these Zr + Sn is 0.1% or more.

Si: ≦ 0.2% Si is an element effective for improving the strength, and it is also effective to add Si. However, if the content exceeds 0.2%, the upper limit is set to 0.2% in order to lower the grain boundary strength and lower the ductility. A desirable content is 0.02% or more.

O: ≦ 0.2% O is effective for improving the strength of the Ti alloy. However, if the content is more than 0.2%, the toughness and the ductility are reduced, so the upper limit is made 0.2%. Desirable content is 0.05%
That is all.

N + C: ≦ 0.1% N and C are effective in improving the strength similarly to O, and one or two of them can be added up to a maximum of 0.1%. However, if the content exceeds 0.1%, toughness and ductility decrease, so the upper limit is made 0.1%. Desirable content is 0.005% or more.

[0020]

Next, embodiments of the present invention will be described in detail. Table 1
Was melted in an argon arc melting furnace, and the alloy was cast using a Ti casting machine to form a 25 × 1
A sample of 0 × 1.5 mm was obtained. Thereafter, the surface was polished and subjected to a metal ion elution test as a test piece of 20 × 10 × 1.0 mm. In addition, a test piece having a diameter of 3 mm and a distance between gauge points of 15 mm according to ISO 6871 was cast and subjected to a tensile test.

Here, the dissolution test was performed by immersing in 1% lactic acid at 310 K for 30 days using a 20 ml polyethylene container.
The elution amount of metal (Ti) was measured using a CP spectrometer.
In the tensile test, the test piece was pulled at a pulling speed of 1 mm / min, and the tensile strength and elongation were determined. The result is Ti-6A
Table 1 in comparison with 1-4V, Ti-6Al-7Nb
Are also shown.

[0022]

[Table 1]

As can be seen from the results in Table 1, Ti-6Al-7Nb in which V was substituted by Nb (Comparative Example of No. 11) was replaced by Ti-6Al-4V (Comparative Example of No. 12). An alloy in which the amount of elution of Ti is reduced as compared to the above, and an alloy using Ta instead of V and Nb as an alloy element (Comparative Example of No. 1)
In the case of, the elution amount of Ti is further reduced as compared with Ti-6Al-7Nb.

On the other hand, in the case of the Ti alloy of the present invention containing various reinforcing elements, the elution amount of Ti is Ti-Al-
While maintaining almost the same level as the Ta alloy, the tensile strength is T
It is even higher than i-Al-Ta alloy and Ti-Al-Nb alloy, and in particular, those of No. 7, No. 8, No. 9, and No. 10 have almost the same level as Ti-6Al-4V. Or more.

The elongation of Ti-6Al-7Nb
, And shows higher elongation than the Ti-6Al-4V alloy, and has excellent ductility.

From these results, it can be seen that the Ti alloy of the present invention is excellent as a biomaterial. Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention can be implemented in various modified forms without departing from the gist of the invention.

Claims (1)

[Claims] (1) Al: 4.0 to 7.0% by weight Ta: 8.0 to 18.0% by weight, and (Nb + Mo), (Zr + Sn), S
One or more of i, O and (N + C) are Nb + Mo: ≦ 1.0% Zr + Sn: ≦ 1.0% Si: ≦ 0.2% O: ≦ 0.2% N + C: ≦ 0.1% A titanium alloy for living body having excellent resistance to dissolution in a living body, characterized in that it is contained in the range of (1) and the balance is substantially composed of Ti.