JPH10130757A - Inplant made of ti alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight inplant excellent in suitable for an organism and having high strength at a low cost. SOLUTION: A stock having an alloy compsn. contg. by weight, 5.3 to 7.5% Al, 6.5 to 8.0% Nb, <=0.30% O, and the balance Ti with inevitable impurities is subjected to casting and molding to from into an inplant material. If required, the alloy compsn. of the stock is composed of the one contg. one or >= two kinds among C, N, Ta and Fe in the ranges of <=0.10% C, <=0.08% N, <=1.0% Ta and <=1.0% Fe and furthermore contg. B in the range of <=0.02%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an artificial bone for medical use,
The present invention relates to an implant material such as an artificial joint implanted in a living body, and more particularly to an implant material made of a Ti alloy.

[0002]

2. Description of the Related Art Artificial bones, artificial joints, and the like are implanted in a living body when a bone or a joint cannot recover its function due to a fracture or various diseases.

As a material for an implant (artificial bone) such as an artificial bone (artificial joint), stainless steel has been put to practical use, and is still used today. 18% initially
Although Cr-8% Ni was used, the corrosion resistance was not sufficient. Therefore, SUS316 system was used. However, the corrosion resistance was still insufficient, and corrosion occurred during long-term implantation in a living body. Some examples have been reported.

Accordingly, attention has been paid to an implant material made of a Ti alloy which is excellent in corrosion resistance and is familiar with a living body, and an implant material made of a forged product of Ti-6Al-4V is actually used. .

[0005] However, it has been pointed out that in the case of an implant made of a forged product of Ti-6Al-4V, V has allergic properties and has a bad effect on the human body. Further, in the case of an implant material made of a forged product, there is a problem that the number of processing steps is increased and the cost is increased.

[0006]

The invention of the present application has been made to solve such a problem. Thus, the implant material according to claim 1 is, by weight%, Al: 5.5 to 5.5%.
7.5%, Nb: 6.5 to 8.0%, O: ≦ 0.30
%, A material having an alloy composition consisting of Ti, Ti and unavoidable impurities, and Ti.

According to a second aspect of the present invention, in the first aspect, the alloy composition of the raw material is further changed by adding at least one of C, N, Ta, and Fe in weight%, and C: ≦ 0.10. %,
N: ≦ 0.08%, Ta: ≦ 1.0%, Fe: ≦ 1.0
% Of the composition.

According to a third aspect of the present invention, in any one of the first and second aspects, the alloy composition of the raw material is further represented by the following formula:
The composition is characterized by being contained in the range of ≦ 0.02%.

A fourth aspect of the present invention is characterized in that, in any one of the first, second, and third aspects, after the casting, HIP processing is performed at a temperature of 800 ° C. or more and β transus or less.

A fifth aspect of the present invention is the method according to any one of the first, second, and third aspects, wherein after performing the HIP treatment at a temperature of 800 ° C. or more and β transus or less after the casting, 600-
It is characterized by being annealed at a temperature of 850 ° C.

[0011]

The implant material of the present invention comprises the above Ti-6Al.
-4V allergic problem is pointed out V
Is substituted with Nb, has excellent compatibility with living organisms, is lightweight and has high strength, and is suitable as an implant material. Further, since it is a cast product, the labor for processing is significantly reduced, and the cost can be reduced.

In the present invention, various casting methods can be used. In particular, those obtained by the reduced pressure suction precision casting method can obtain a fine cast surface, and have a thin-walled complicated shape product (minimum wall thickness: 0.3 mm). Is desirable because it can be easily obtained.

FIG. 1 schematically shows an embodiment of the vacuum suction precision casting. In the figure, 10 is a decompression chamber, 12
Is a vacuum suction port, and 14 is a porous ceramic shell mold set in the vacuum chamber 10. A melting furnace 16 has a high-frequency induction heating coil 20 wound around the outer periphery of a water-cooled copper crucible 18.

In this vacuum vacuum suction precision casting, the alloy material 22 is heated in a high-frequency induction heating coil 20 under an inert atmosphere.
Induction heating. At this time, in the molten alloy, the magnetic field due to the current induced in the surface layer and the magnetic field due to the current generated in the wall of the water-cooled copper crucible 18 have phases opposite to each other. Thus, the crucible 18 is separated from the wall. That is, the molten alloy separates from the inner wall surface of the crucible 18 and becomes in a floating state.

Then, vacuum suction is performed from the vacuum suction port 12 to make the interior of the vacuum chamber 10 under reduced pressure, and a negative pressure is applied to the inside of the porous ceramic shell mold 14. Is sucked up to the ceramic shell mold 14 side and filled inside the mold 14.

Thereafter, by cooling the mold 14 and the molten alloy, a casting having a shape corresponding to the ceramic shell mold 14 is obtained.

[0017] According to the vacuum suction precision casting method, the molten alloy can be poured gently and quickly into the mold, and the molten alloy can be poured and filled all over the mold. A product with a small number of defects and a thin complex shape can be easily cast, and the casting surface can be made a fine and good casting surface. Therefore, unlike an implant material made of a forged product, subsequent machining can be largely omitted, and the cost can be reduced.

In the present invention, C,
Any one or more of N, Ta, and Fe may be C ≦
0.10%, N ≦ 0.08%, Ta ≦ 1.0%, Fe ≦
It can be contained in a range of 1.0% (claim 2),
Thereby, the strength of the implant material can be effectively increased. Further, it can be contained in the range of B ≦ 0.02% (claim 3), whereby the crystal grains in the implant material can be refined.

Next, the implant material according to claim 4 is subjected to HIP treatment at a temperature of 800 ° C. or more and β transus or less after casting. In the case of this implant material, casting defects such as cavities generated during casting are compressed. And have good ductility.

Here, β transus means β phase and (β + α)
A phase boundary, that is, a transformation point from the β phase to the (β + α) phase. The reason why the HIP treatment is performed at a temperature equal to or lower than β transus in the fourth aspect is that the crystal grains become coarser when the HIP treatment is performed at a temperature higher than β transus, that is, in the β phase region.

The implant material according to the fifth aspect is characterized in that the HIP
In addition to the treatment, it is further subjected to an annealing treatment at a temperature of 600 to 850C, and the ductility can be further increased by this treatment.

Next, the reasons for limiting each chemical component in the present invention will be described in detail below. Al: 5.5 to 7.5% Al is embrittlement caused by formation of an intermetallic compound Ti ₃ Al when the strength is less than 5.5% can not be ensured, On the other hand more than 7.5%. Therefore, in the present invention, Al is 5.5 to 5.5.
Limited to 7.5%.

Nb: 6.5-8.0% If Nb is less than 6.5%, the strength cannot be secured, and if Nb exceeds 8.0%, the specific gravity increases, and Nb is an expensive material. This leads to an increase in cost. Therefore, in the present invention, Nb is limited to the range of 6.5 to 8.0%.

O: ≦ 0.30% (preferably 0.05 to
0.25%) O is an effective element for increasing the strength, but 0.30%
If it exceeds, the toughness will decrease. Therefore, in the present invention, the content of O is limited to 0.30% or less. The preferred content is 0.05 to 0.25%.

C: ≤0.10% (preferably ≤0.07%)
%) N: ≤ 0.08% (preferably ≤ 0.05%) Ta: ≤ 1.0% Fe: ≤ 1.0% These C, N, Ta, and Fe are all effective as reinforcing elements for implant materials. Element. Of these, C and N are effective for improving strength, but 0.10% and 0.08%, respectively.
If N exceeds N, the toughness is significantly reduced.
, The upper limits were set to 0.10% and 0.08%. Each preferred range is C ≦ 0.07%, N ≦ 0.05.
%.

Next, Ta is an element contained in the Nb raw material and is known to have good biocompatibility. However, if the content exceeds 1.0%, the specific gravity becomes heavy and the cost becomes high, so the upper limit is set to 1.0%.

Fe is an element having the same function as Nb and Ta, and can be added as needed. However, Fe is an element that easily segregates, and if it exceeds 1.0%, segregation becomes a problem. Therefore, the upper limit is set to 1.0%.

B: ≦ 0.02% Since B has an effect of refining crystal grains, it can be added up to 0.02% in the present invention. However, if it exceeds 0.02%, the ductility decreases and the material becomes brittle, so the upper limit was made 0.02%.

HIP treatment: 800 ° C. to β-transus temperature HIP treatment is effective for compressing casting defects such as cavities generated at the time of casting as described above and improving ductility. However, if the temperature is lower than 800 ° C., the casting defect cannot be effectively pressed, and if the temperature exceeds the β transus temperature, the crystal grains become coarse and the ductility decreases. Therefore, in the present invention, the HI
P processing is performed. The pressure condition is 1000 kg / c
It can be employed m ² or more.

Annealing treatment: 600 to 850 ° C. Annealing at 600 to 850 ° C. is effective in adjusting the balance between strength and ductility of the implant material. However, the strength is practically unchanged at a temperature lower than 600 ° C., and the strength is reduced at a temperature higher than 850 ° C., so that the temperature condition needs to be 600 to 850 ° C.

[0031]

Next, embodiments of the present invention will be described in detail. Table 1
1 was subjected to reduced pressure suction precision casting according to the method shown in FIG. 1 to produce an implant material 25 having the form shown in FIG. Here, the implant material 25 is for an artificial hip joint.

[0032]

[Table 1]

Incidentally, in the column of HIP in the table, for example, 900 ° C. × 3
h × 1220 kg / cm ² means temperature (900 ° C.), time (3 h) and pressure (1220 kg / c
m ² ).

Furthermore, 3, No. 5, No. For No. 9, an annealing treatment was performed after the HIP treatment. Tensile test piece (JIS No. 14 test piece) from the obtained implant material 25
Was cut out and subjected to a tensile test. The obtained results are shown in the table together with the comparative examples.

From the above results, it can be seen that even in the case of the cast implant material, which tends to have lower ductility than the forged implant material, the implant material of this example shows good ductility as well as strength. .

Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention is not limited to the above-described hip prosthesis, but includes various joints such as knee joints, elbows, shoulders, fingers, and other artificial bones. The present invention can be embodied in variously modified forms without departing from the gist thereof, such as being generally applicable to living materials including living organisms.

[0037]

As described above, the implanted Ti alloy implant material of the present invention is excellent in compatibility with living organisms, is lightweight and has high strength, and is a cast product, so that the processing time is reduced. The effect is excellent in practical use, such as being extremely small and inexpensive.

[Brief description of the drawings]

FIG. 1 is a view schematically showing one embodiment of a vacuum suction precision casting method as a casting method employed in the present invention.

FIG. 2 is a view showing the shape of an artificial bone for a hip joint as an implant material manufactured in an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Decompression chamber 12 Decompression suction port 14 Ceramic shell mold 16 Melting furnace 18 Water-cooled copper crucible 20 High-frequency induction heating coil 25 Implant material

Claims (5)

[Claims] 1. An alloy composition consisting of Al: 5.5 to 7.5% Nb: 6.5 to 8.0% O: ≤ 0.30% by weight% An implant material made of Ti alloy. 2. The alloy according to claim 1, wherein the alloy composition of the raw material further comprises C: ≦ 0.10% N: ≦ 0. 08% Ta: ≦ 1.0% Fe: ≦ 1.0% A Ti alloy implant material characterized in that it has a composition in the range of: 3. The Ti alloy according to claim 1, wherein the alloy composition of the material further includes B: ≦ 0.02% by weight. Implant material. 4. The Ti alloy implant material according to claim 1, wherein the HIP treatment is performed at a temperature of 800 ° C. or more and β transus or less after the casting. 5. The method according to claim 1, wherein after the casting, a HIP treatment is performed at a temperature of 800 ° C. or more and β transus or less, and then an annealing treatment is performed at a temperature of 600 to 850 ° C. An implant material made of Ti alloy, characterized by the following.