JP3176233B2 - Biological implant components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a living body implant member used for a hip joint, a shoulder joint, a knee joint or the like of a living body.

[0002]

2. Description of the Related Art Metals, polymers, ceramics, and the like have conventionally been used as materials for biological implants for restoring bone and joint functions lost due to illness or accident. These are required to have biocompatibility, static strength, abrasion resistance, etc., but recently they are used for aircraft engines, etc.
Titanium or T with excellent specific strength, corrosion resistance and biocompatibility
Titanium alloys such as i-6Al-4V alloy have been used.

In recent years, the use of titanium-based metals has been expanding not only as aircraft members, but also as mechanical structural members such as marine development equipment, automobiles, chemical industrial plants, medical tools and the like. No. 185964 discloses an invention of a lightweight structural material having excellent oxidation resistance by forming a Ti-Al-based intermetallic compound layer on a surface of a base material made of titanium or a titanium alloy via a titanium oxide-based layer. The use has been expanded in the fields of the bicycle and aerospace industries.

When such a titanium-based metal is used for medical use, it has excellent specific strength, corrosion resistance, and biocompatibility as described above, but has difficulty in abrasion resistance. Many attempts have been made to combine with alumina which has improved wear resistance or is extremely poor in toughness, but is also excellent in corrosion resistance and wear resistance.

As such a proposal, for example, US Pat. No. 4,693,760 describes a method in which wear resistance is greatly improved by ion implantation of N, C ions and the like.

In Japanese Patent Application Laid-Open No. 5-317346, Ti
_{N, Zr, TiB 2, Al} 2 O 3, the implant member coated on the surface of the metal alloy hard ceramic material of the diamond to a thickness of 5~15mm is described.

In Japanese Patent Application Laid-Open No. 62-122669,
Ti, Nb, Ta, B,
Si, Zr, Hf, W, Mo, Al nitride, carbide,
A biological implant member coated with a boride, a carbonitride, a carbonate, a carbonitride, or an oxide at 0.1 to 30 μm is described.

Japanese Patent Application Laid-Open No. 5-168691 discloses an artificial joint in which a slightly soft alumina layer containing 3% of titanium oxide is sprayed on the surface of a metal artificial bone head and white alumina is sprayed on the alumina layer. .

In Japanese Patent Application Laid-Open No. 4-295354, a ceramic coating layer is formed by explosive spraying on the sliding surface of an artificial joint having a sliding portion, and the coating layer is mirror-finished to provide sliding and wear resistance. Is described as being improved.

[0010]

However, the above prior art has the following problems. That is, the conventional surface modification method by the ion implantation treatment has excellent controllability of the treatment and has an advantage of a low-temperature treatment, but it is troublesome because a large amount of ions must be implanted in order to produce an effect. The cost is high. It is also reported that the segregation of implanted atoms causes characteristic deterioration, and that the treated film peels off due to residual strain.

Further, as described above, forming a film having a thickness of 5 to 15 .mu.m by a coating method using a normal PVD method requires a very high cost as compared with a normal thickness of 2 to 4 .mu.m. And peeling easily occur.

In addition, thermal CVD, plasma CV
D, when a surface film is formed by laser CVD or ion plating, cracking or peeling of the film easily occurs.

Since the alumina ceramic layer formed on the metal surface has a thickness of 100 to 300 μm, the adhesive strength at the interface between the metal and the film is very small, so that it is easy to peel off.

Further, when the coating layer is mirror-finished as described above, there is a problem that the cost is high and the coating layer is formed by explosive spraying, so that the mirror surface must be finished.

[0015]

In order to solve the above-mentioned problems of the prior art, the present invention provides a method for forming a layer containing titanium, aluminum and oxygen on a surface portion of a substrate made of titanium or a titanium alloy by, for example, oxygen ion beam mixing. Thick
After forming an ion mixing layer of 1 to 100 nm , A
there is provided a biomedical implant member characterized by coating the surface membrane of l ₂ 0 _3.

[0016]

[Action] Cobalt-chromium-molybdenum alloy is often used as a metal material for a biological implant, but elution of metal ions due to corrosion after being placed in a biological tissue of a human body for a long time has been reported. For this reason, if a titanium-based metal such as titanium or a titanium alloy is used as the base material, the biocompatibility is much better than the cobalt-chromium-molybdenum alloy in terms of corrosion resistance, but the wear resistance is poor. Inferior. Therefore, Al ₂ O
_3. Coat the surface film.

In this case, when Al ₂ O ₃ is directly coated on a titanium-based metal substrate, the adhesion is weak, and the surface film is easily peeled off.
In addition, the hardness of the base material is relatively high, and the hardness of the surface film may be insufficient due to the influence.

Therefore, in the present invention, an ion mixing layer containing a base material component, aluminum and oxygen is formed on the surface of the base material by oxygen ion beam mixing, and then the surface film of Al ₂ O ₃ is coated.

This ion mixing layer is formed at the time of pretreatment when forming a surface film of Al ₂ O _3. At the same time as oxygen ions are implanted, aluminum and a base material deposited by collision with the implanted ions are removed. The components are pushed into the substrate. Further, the pushed moving particles are mixed by collision. Therefore, the ion mixing layer is an intermediate layer between the surface film of Al ₂ O _{3 and} a mixture of aluminum and base components. The modified surface by the ion implantation treatment has an implantation amount of 10 ¹⁷ to 10 ¹⁸ ions / cm ^2.
But the ion mixing layer is 10 ¹⁵ to 10 ¹⁶
It can be formed at about ions / cm ² .

As a function of the implant member for living body thus configured, excess oxygen ions are mixed into the base material, thereby increasing the nucleation density and increasing Al _2.
The crystal structure in the surface film of O ₃ is good, and therefore, the strength, hardness and surface smoothness of the surface film are very excellent.

In addition, since the continuity between the substrate and the surface film is realized by the above-mentioned mixing, the adhesion strength between them is large, and the surface film is hardly peeled off.

Further, since surplus metal ions are not generated by the surface film, there is no concern about adverse effects on living organisms due to elution of metal ions.

The preferred thickness of the surface layer is 0.1
５5 μm. If the film thickness is larger than 5 μm, cracking and delamination may occur due to an increase in residual stress, and surface irregularities may increase, which may require a mirror finish after coating. On the other hand, if the film thickness is smaller than 0.1 μm, the durability may be reduced. A more preferable thickness is 0.7 to 2 μm, and the thickness may be arbitrarily selected in consideration of surface roughness, film formation cost, and the like.

The preferred thickness of the ion mixing layer is 1 to 100 nm. If the layer thickness is less than 1 nm, the cushioning effect is expected to be slightly insufficient,
On the other hand, if it is larger than 100 nm, there is a possibility that the layer may be easily broken.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show an artificial bone head 1 as a living body implant member of the present invention constituting an artificial hip joint A. In the artificial hip joint A, the head 1 is fitted to the tip of a stem 2. The head 1 has a titanium alloy substrate 3 with a surface film 5 of Al ₂ O ₃ coated on the outermost surface thereof through an ion mixing layer 4 containing titanium, aluminum and oxygen.

Hereinafter, a method of forming the ion mixing layer 4 and the surface film 5 on the head 1 will be described. The titanium alloy base material 3 is a Ti-6Al-4V alloy, and is mirror-finished to a surface roughness Ra = 50 nm by a spherical machining machine. This was set on a sample holder 6 which revolves around itself in an IBAD apparatus (ion beam assisted deposition apparatus) as shown in FIG. This IBAD apparatus forms a thin film by irradiating an oxygen ion beam from the ECR ion source 8 onto the surface of the base material 3 if the vacuum deposition amount of Al from the electron beam vacuum evaporation source 7 is monitored by a film thickness monitor. is there.

After setting the titanium alloy substrate 3 in the sample holder 6 of the IBAD apparatus, the inside of the apparatus is set to 2 × 10 ^-6 T
The vacuum was applied to orr, and the surface was cleaned with alumina ions of 2 KeV. Subsequently, ion irradiation is performed under the conditions of oxygen ion beam energy: 20 KeV and transport ratio Al / O = 0.5, and further, the surface layer of Al ₂ O ₃ is performed under the condition of oxygen ion beam energy 5 KeV and transport ratio Al / O = 2. Was formed in a thickness of 1 μm.

After the above coating operation, it was confirmed by X-ray diffraction measurement that α-Al ₂ O ₃ was formed on the surface of the head 1. Further, composition analysis in the depth direction by XPS was performed. As a result, the ion mixing layer 4 containing titanium, aluminum and oxygen has a thickness of 50 nm, α-Al ₂
The surface film of O ₃ was 1.0 μm.

Further, when the hardness and the surface roughness were measured, the micro Vickers hardness was 1200 and the surface roughness was 50 nm, which was unchanged.

(Experimental Example 1) 40 × 10 × 6 mm titanium alloy test piece (Ti-6Al-4V) 40 × 10 mm
The surface, using the IBAD device, to form a surface layer of the ion mixing layer and Al ₂ O ₃ in the same manner. As a comparative example, a titanium alloy test piece which had not been subjected to any coating treatment and a cobalt / chromium alloy were prepared, and a wear test by PIN ON FLAT friction was performed, and the surface condition was visually observed. Table 1 shows the results.

[0031]

[Table 1]

As is apparent from Table 1, the test piece of the present invention having the ion mixing layer and the surface film of Al ₂ O ₃ formed thereon was smaller than the titanium alloy and the cobalt / chromium alloy test piece.
Exhibited abraded wear characteristics.

(Experimental Example 2) A 10 × 15 × 1.5 mm titanium alloy test piece (Ti-6Al-4V) having a size of 10 × 15 was used.
An ion mixing layer and a surface layer of Al ₂ O ₃ were formed on the surface of mm in the same manner as in Experimental Example 1. Further, as a comparative example, a test piece coated with TiN having a thickness of 1 μm by a normal PVD method was prepared.

A scratch test was performed on a 10 × 15 surface of these test pieces with a diamond needle. Table 2 shows the results.

[0035]

[Table 2]

As is clear from Table 2, the results of the test piece of the present invention were significantly higher than those of the TiN-coated test piece.

(Experiment 3) In the method of the above embodiment,
The thickness of the ion mixing layer 4 was set as shown in Table 3 by adjusting the Al / O ratio to the ion irradiation time, and the artificial bone head 1 as a biological implant member of the present invention was produced. The thickness of the surface film 5 of Al ₂ O ₃ was 1 μm.

[0038]

[Table 3]

With respect to these artificial heads 1, the micro Vickers hardness was measured. Table 3 shows the results.

As is clear from Table 3, the micro Vickers hardness was particularly large when the thickness of the ion mixing layer 4 exceeded 10 nm.

(Experimental example 4) In the same manner as in Experimental example 1,
Table 4 shows the thickness of Al ₂ O _{3 and} the thickness of the ion mixing layer.
Various test pieces were prepared in the same manner.

[0042]

[Table 4]

With respect to such a test piece, the Knoop hardness was measured, and the number of cycles until the Al ₂ O ₃ film was peeled off at a temperature between 25 ° C. and 300 ° C. for 1 minute in air was measured. Table 4 shows the results.

As is clear from Table 4, each of the samples exhibited high values of both thermal shock resistance and Knoop hardness, but excellent results were obtained especially when the thickness of the ion mixing layer was 20 to 70 nm.

[0045]

As described above, the implant member for a living body according to the present invention has a high nucleation density due to the mixing of oxygen ions into the base material, thereby increasing the nucleation density in the surface film of Al ₂ O _3. The crystal structure is good, so the strength of the surface film,
Excellent in hardness and surface smoothness.

In addition, since the continuity between the substrate and the surface film is realized by the above-mentioned mixing, the adhesion strength between them is large, and the surface film is hardly peeled off. Further, according to the present invention, the ion
By setting the thickness of the mixing layer to 1 to 100 nm,
The on-mixing layer is not
Can provide sufficient strength.

Further, since surplus metal ions are not generated by the surface film, there is no fear of adverse effects on living organisms due to elution of metal ions.

Al ₂ O ₃ which is excellent in biocompatibility
Since the film is coated with sufficient adhesion strength, the amount of wear caused by vibration with high-density polyethylene can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a side view of an artificial hip joint equipped with an artificial head as an implant member for a living body according to an embodiment of the present invention.

FIG. 2 is a central sectional view of the artificial head shown in FIG. 1;

FIG. 3 is a schematic view of an apparatus used for a coating operation in an embodiment of the present invention.

[Explanation of symbols]

 A artificial hip joint 1 (artificial) head 2 stem 3 base material 4 ion mixing layer 5 surface film 6 sample holder 7 electron beam vacuum evaporation source 8 ECR evaporation source

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) A61L 27/00 C23C 14/00-14/58

Claims (1)

(57) [Claims] The thickness of a layer containing titanium, aluminum and oxygen is 1 to 1 on the surface of a substrate made of titanium or a titanium alloy .
Biological implant member obtained by coating the surface layer of Al ₂ 0 ₃ via ion mixing layer of 100 nm.