JPH0568707A - Artificial articulating capital ball made of ti or ti alloy with excellent abrasion resistance and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an artifical articulating capital ball made of Ti or Ti alloy and having excellent abrasion resistance and a simple manufacturing method therefor. CONSTITUTION:(1) An artificial articulating capital ball made of Ti or Ti alloy with excellent abrasion resistance and having an oxygen diffusion solid hard layer on its surface and (2) a method for casting the artificial articulating capital ball made of Ti or Ti alloy and having excellent abrasion resistance whereby Ti or Ti alloy is casted into a zirconia ceramics mold having a composition comprising one or two kinds of alumina (2 to 50wt.%) and titania (2 to 30wt.%) and the rest zirconia in such a manner that the total amount of the alumina and the titania does not exceed 50wt.%.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head ball for artificial joints made of Ti or Ti alloy having excellent wear resistance and a method for producing the same.

[0002]

2. Description of the Related Art In general, Ti or Ti alloy is a metal having excellent corrosion resistance, particularly excellent corrosion resistance to human tissues and body fluids, and further to human tissues, inflammation, hypersensitivity, allergies, caries. It is used as an implant material to be embedded in a living body such as an artificial joint or an artificial tooth root because it does not cause such problems.

However, Ti or Ti alloys are also known to have poorer wear resistance than other implant materials. Therefore, a portion requiring wear resistance, for example, a head portion ball portion of a Ti or Ti alloy artificial joint forms a nitride layer on its surface by a method such as a gas nitriding method, an ion nitriding method, or an ion implantation method, Attempts have also been made to improve wear resistance (see Japanese Patent Laid-Open No. 1-148263).

[0004]

However, the above Ti
Alternatively, the hard nitriding layer formed on the surface of the Ti-alloy head bone ball for artificial joints by the above-mentioned gas nitriding method, ion nitriding method or the like has a layer thickness of about 0.02 to 0.2 μm, and is thicker than this. Since it is difficult to do so, there is a problem that a sufficient layer thickness cannot be formed against abrasion and it cannot be used for a long period of time.

[0005]

Therefore, the present inventors have
As a result of research to solve such problems, alumina:
2 to 50% by weight, titania: 2 to 30% by weight, containing 1 or 2 types, and 2 or more of the above alumina and titania
If the total amount of the seeds is contained in a range not exceeding 50% by weight, and the Ti or Ti alloy-made femoral head ball for artificial joints is cast using a zirconia-based ceramic mold having a composition of the rest being zirconia, A part of the oxygen reduced from the alumina and titania diffuses and forms a solid solution on the surface of the Ti or Ti alloy artificial head ball casting for artificial joints, and the surface of the Ti or Ti alloy artificial head ball casting for artificial joints has a Vickers hardness of 400. The above oxygen-diffused solid solution hard layer having excellent wear resistance is formed, and the oxygen-diffused solid solution hard layer retains excellent wear resistance for a long period from the thickness of at least 100 μm or more. I got the knowledge that I can.

The present invention was made on the basis of such findings, and (1) Ti or T having excellent wear resistance is characterized by having an oxygen diffusion solid solution hard layer on the surface.
i alloy bony head for artificial joints, and (2) 1 to 2 kinds of alumina: 2 to 50% by weight and titania: 2 to 30% by weight, the total amount of alumina and titania exceeds 50% by weight. To the zirconia-based ceramic mold containing T.
The present invention is characterized by a casting method of a Ti or Ti alloy femoral head ball for artificial joints, which is excellent in wear resistance, for casting an i or Ti alloy.

[0007] In the method of casting the above-mentioned Ti or Ti alloy femoral head ball for artificial joints, Ti or Ti alloy is cast into the above-mentioned ceramic mold, and then immediately Ti or Ti is used.
If the alloy-made bone head ball casting for artificial joints is kept at a high temperature below the melting temperature of Ti or Ti alloy for a predetermined period of time without being taken out, the oxygen diffusion solid solution is further promoted, and a thick oxygen diffusion solid solution hard layer is formed. Obtainable.

Next, the reason for limiting the numerical values in the present invention will be described. In the present invention, the oxide that can be contained in the zirconia-based ceramic mold is sufficient if it can easily release oxygen at a higher temperature than zirconia, but oxides having a low melting point such as silicon dioxide are not preferable, and alumina and titania are preferable. Is preferred. In that case, if the content of alumina and titania is less than 2% by weight, the desired effect cannot be obtained because the thickness of the oxygen solid solution diffusion hard layer obtained is small, while the content of alumina exceeds 50% by weight or the titania content is 30% or less. If the content is more than 10% by weight, the surface of the casting becomes rough and, at the same time, the surface becomes brittle and the desired effect as a head ball for an artificial joint cannot be obtained.

Even if alumina is 50% by weight or less and titania is 30% by weight or less, if alumina and titania are contained at the same time, the total amount is 50% by weight.
If it is not set to the following, the surface of the casting becomes rough and at the same time the surface becomes brittle, which is not preferable.

FIG. 1 is a sectional view of the femoral head ball for artificial joints according to the present invention. An oxygen-diffused solid solution hard layer 3 is formed on the surface of the femoral head ball 1 for an artificial joint of the present invention,
It is used by being fitted to the tip of the stem portion 2 of the artificial joint shown by the dotted line in FIG.

[0011]

EXAMPLES The present invention will be specifically described based on examples. First, zirconia-based ceramic molds A to K having the component compositions shown in Table 1 were prepared.

On the other hand, a Ti alloy having a composition of Ti-6% Al-4% V was melted, and the molten Ti alloy was cast into zirconia-based ceramic molds A to K having the composition shown in Table 1, and the diameter was: The hip head balls for artificial hip joints of Examples 1 to 7 and the femoral head ball for artificial hip joints of Comparative Examples 1 to 4 having a size of 25 mm were manufactured.

The surface condition of the castings of the obtained artificial head joint ball for artificial hip joints of Examples 1 to 7 and comparative example 1 to 4 was observed, and the depth of the formed oxygen diffusion solid solution hard layer was observed. And the thickness of an effective oxygen diffusion solid solution hard layer having a Vickers hardness of 400 Hv or more are measured, and a femoral head ball for an artificial hip joint is applied to high density polyethylene and a load is 2
50 kgf, rotation speed: 60 r. p. m. The specific wear amount = wear volume / load × wear distance was measured by pressing for 70 hours under the condition of 1. and the results are shown in Table 2.

Further, pure Ti is melted, and this pure Ti molten metal is cast into zirconia-based ceramic molds A to K having the composition shown in Table 1, kept at a temperature of 1250 ° C. for 10 minutes, and a diameter of 25 mm. The artificial head joint ball for artificial hip joints of Examples 8 to 14 and the artificial head joint ball for artificial hip joints of Comparative Examples 5 to 8 were produced.

The surface condition of the casting of the obtained bone head ball was observed, and then the depth of the formed oxygen diffusion solid solution hard layer and the thickness of the effective oxygen diffusion solid solution hard layer having a Vickers hardness of 400 Hv or more were measured. In addition, the hip head ball for artificial hip joints is made of high density polyethylene, load: 250kgf, rotation speed:
60r. p. m. The specific wear amount = wear volume / load × wear distance was measured by pressing for 70 hours under the above condition, and the results are shown in Table 3.

From the results shown in Tables 1 and 2, a Ti or Ti alloy femoral head ball cast in a ceramics mold H made of zirconia alone does not cause surface roughening, but has a sufficient depth of hardness. No layer is obtained, while Ti or Ti cast using ceramic molds I and J containing alumina and titania in excess of 50 wt% and 30 wt% respectively and ceramic mold K containing silica or It is understood that the Ti-alloy bone head balls for artificial hip joints are not preferable because the surface thereof is roughened.

[0017]

[Table 1]

[0018]

[Table 2]

[Table 3]

[0019]

INDUSTRIAL APPLICABILITY The present invention makes it possible to easily obtain a femoral head ball for an artificial joint having an oxygen solid solution diffusion hard layer on the surface simply by casting Ti or a Ti alloy in a zirconia-based ceramic mold having a specific component composition. The oxygen solid solution diffusion hard layer has a desired hardness, and a hard layer thicker than before can be obtained, so that it can withstand long-term wear, and the thickness of the hard layer Since it is thick, it is possible to polish the surface if necessary, which is an excellent effect in the medical industry.

[0020]

[Brief description of drawings]

FIG. 1 is an explanatory sectional view of a femoral head ball for an artificial joint,

[Explanation of symbols]

 1 Bone head ball for artificial joint, 2 Stem part of artificial joint, 3 Oxygen diffusion solid solution hard layer,

Claims (5)

[Claims] 1. A femoral head ball for artificial joints made of Ti or Ti alloy having excellent wear resistance, which has a hard layer of oxygen-diffused solid solution on its surface. 2. A Ti or Ti alloy having excellent wear resistance, which comprises casting Ti or a Ti alloy in a zirconia-based ceramic mold containing alumina: 2 to 50% by weight and the balance being zirconia. Casting method for alloy head ball for artificial joint. 3. Ti or Ti having excellent wear resistance, characterized in that Ti or Ti alloy is cast in a zirconia-based ceramic mold having a composition containing 2 to 30% by weight of titania and the balance being zirconia. Casting method for alloy head ball for artificial joint. 4. Alumina: 2 to 50% by weight, titania:
Casting Ti or Ti alloy into a zirconia-based ceramic mold containing 2 to 30% by weight, and containing the above alumina and titania in an amount not exceeding 50% by weight, the balance being zirconia. A method for casting a femoral head ball for artificial joints made of Ti or Ti alloy, which has excellent wear resistance. 5. The zirconia-based ceramic mold according to claim 2, 3 or 4 is cast with Ti or a Ti alloy, and then kept at a temperature lower than the melting temperature of the Ti or Ti alloy for a predetermined time. Casting method of Ti or Ti alloy head ball for artificial joints with excellent wear resistance. [0001]