JP2001089224A - Ceramic biomember - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic biomember comprising aluminous ceramics, in particular a joint member excellent in wear resistance. SOLUTION: The ceramic biomember comprises aluminous ceramics containing at least 0.5-10 wt.% (expressed in terms of TiO2) Ti or <=5 wt.% (expressed in terms of MgO) Mg, part or all of which is allowed to enter into solid solution in the alumina grains, and further containing dispersed oxide grains containing at least one selected from Zr, Hf and group IIIa elements in the grain boundaries of the alumina grains.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, artificial bones,
The present invention relates to a ceramic biological member such as an artificial tooth root, and particularly to a ceramic biological member suitable as an artificial joint member.

[0002]

2. Description of the Related Art Conventionally, a ceramic biological member has been used, for example, as an artificial hip joint, an artificial joint member comprising a metal stem, a metal or ceramic head, and a socket made of ultra-high molecular weight polyethylene has been used. ing.

[0003] For example, Japanese Patent No. 2579212 and Japanese Patent Publication No. 7-94344 disclose alumina containing 99.5% by weight or more, with the balance being Mg, Ca, Ba, Sr, Sr.
It is disclosed that a high-purity alumina ceramic made of at least one of c, Y, La, and Ce becomes a living body member having excellent biocompatibility. In addition, biomaterials made of zirconia ceramics or the like other than alumina have been proposed.

Further, a joint having a structure in which the head and the socket are made of ceramics and the ceramics are brought into direct contact with each other and slid, has been proposed, and it has been proposed that the wear resistance can be improved.

[0005]

However, the above-mentioned living body made of high-purity alumina ceramics is excellent in biocompatibility but has a bending strength of at most 80 kg / mm ^2.
It is likely to break or break in vivo, and when the head and socket are made of alumina ceramics and the ceramics slide with each other, the wear resistance is not sufficient and the ceramics There was a risk that the sliding part of the bearing would be worn. In addition, biomaterials made of zirconia ceramics have a problem in that, although they are excellent in toughness, they have low abrasion resistance. For example, when used as a head of a joint member, the head is worn.

An object of the present invention is to provide a living body member made of alumina ceramics which has high strength and excellent wear resistance and does not adversely affect the living body.

[0007]

Means for Solving the Problems As a result of studying the above problems, the present inventors have found that at least 0.5 to 10% by weight of Ti in terms of TiO _{2 is} contained, and a part or all of Ti is contained in the alumina crystal. It has been found that the wear resistance of a biological member can be dramatically improved by using an alumina ceramic formed as a solid solution in a biological member.

[0008] In addition, M
5 wt% or less in terms of MgO, and a part or all of Mg is dissolved in alumina crystals, and Ti-containing oxide crystals are precipitated and dispersed in the alumina crystals by 0.5 vol% or more. It is preferable that the Mg-containing oxide crystal is precipitated and dispersed in the alumina crystal by 0.5% by volume or more.

Further, Z is added to the grain boundary of the alumina crystal.
It is desirable that an oxide crystal containing at least one of r, Hf, and group 3a elements be present.

[0010] The ceramic biological member of the present invention can be particularly suitably used as an artificial joint member.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic sectional view of an artificial hip joint which is an example to which a ceramic biomaterial according to the present invention is applied.
Shown in According to FIG. 1, the hip prosthesis 1 is made of Ti alloy, C
A head 4 is fitted to a tapered portion of a stem 2 having a tapered portion at the tip made of a metal such as an o-Cr alloy or stainless steel.
It has a configuration in which the head 3 can rotate.

According to the present invention, the head 3 or the head 3 and the socket 4 are formed by converting at least Ti to 0.5% in terms of TiO _2.
It is a great feature that it is formed of alumina ceramics in which a part or the whole of Ti is dissolved in the alumina crystal while containing 10 to 10% by weight, thereby greatly increasing the friction coefficient of the head 3 and the socket 4. The wear resistance of ceramics can be increased, and when used for joint members, etc., it is possible to prevent wear of the members, reduce wear powder and suppress osteolysis (osteolysis), The loosening of the artificial hip joint 1 can be prevented.

Further, even when sliding with other members such as zirconia and polyethylene, the alumina-based ceramic of the present invention has high abrasion resistance. As a result, the amount of wear of other members can be reduced.

From the viewpoint of such wear resistance, the surface roughness (Ra) of the alumina ceramic is desirably 0.1 μm or less, particularly 0.05 μm or less, and further desirably 0.02 μm or less. Has a relative density of 95
%, Especially 98% or more.

Here, the reason for setting the content of Ti to the above range is that if the content of Ti is less than 0.5% by weight in terms of TiO ₂ , there is no effect of adding Ti, and if the content of Ti is TiO 2 _{If the} amount is more than 10% by weight in terms of ₂ , Ti cannot be completely dissolved in the alumina crystal, and a large amount of Al ₂ TiO ₅ crystal or TiO ₂ crystal precipitates at the grain boundary of the alumina crystal to lower the strength of the ceramic.

Further, the dissolution of Ti into alumina is promoted by the presence of Mg, the abnormal grain growth of alumina can be suppressed, and the wear resistance of the ceramic can be further increased. It is desirable that Mg be contained in an amount of 5% by weight or less in terms of MgO, and that part or all of Mg be dissolved in alumina crystals.

Further, in order to increase the strength of the alumina crystal, a Ti or Mg-containing oxide crystal having an average particle diameter of 0.3 μm or less may be precipitated and dispersed in the alumina crystal in an amount of 0.5% by volume or more. desirable. That is, such T
Since i or Mg-containing oxide crystals can generate structural defects or stresses due to different thermal expansion coefficients in the alumina crystals, a minute amount of Ti or Mg-containing oxide crystals in the alumina crystals is generated around the i or Mg-containing oxide crystals. As a result of generating a stress field and suppressing the growth of external stress and cracks, the strength and toughness of the alumina ceramics can be increased, the wear resistance can be increased, and the risk of breakage can be reduced. Accordingly, it is possible to prevent the loosening between the head 3 and the socket 4 from occurring.

The socket 4 is made of the ceramic ceramic of the present invention.
If it is formed of a body member, the strength of the socket 4 can be improved.
The thickness of the socket 4 can be reduced by the
The amount of human bone resection can be reduced when implanting
You. Furthermore, Ti or Ti that precipitates and disperses in alumina crystals
Is MgAl-containing oxide crystal, MgAl_TwoO_Four, TiO
_Two, Al_TwoTiO_Five, RE_TwoTi_TwoO₇It is desirable that
No.

Further, Z is formed at the grain boundary of the alumina crystal.
It is desirable that an oxide crystal containing at least one of r, Hf and 3a group elements be present, whereby the grain growth of alumina crystal can be suppressed and the grain boundary can be strengthened. As a result, the strength and toughness of the alumina ceramics can be further increased, and the wear resistance can be increased.

Next, a method for producing the above alumina ceramics will be described. First, the average particle size is 0.1 to 2
based on the alumina powder [mu] m, the TiO ₂ 0.5 to 10
And weight%, optionally, MgO mentioned above, ZrO _2, H
fO ₂ and a Group 3a element oxide are added and mixed. In addition,
As the oxide to be added, an oxide powder, a solution of carbonate, nitrate, acetate or the like which can form an oxide by firing, or a solution of an organic salt or the like can be used.

Next, the mixed powder is formed into a predetermined shape by press molding, casting, cold isostatic pressing or the like, and then fired.

A specific firing method is that the compact is heat-treated under a reducing atmosphere to increase the solid solution amount of Ti in alumina, specifically, to reduce the ion valence of Ti from 4+ to 3+.
By changing to +, a solid solution in which Al ³⁺ in the alumina crystal is replaced with Ti ³⁺ to form a solid solution can be produced.

After firing in the above reducing atmosphere,
Firing in an oxidizing atmosphere reduces the amount of Ti that can be dissolved in alumina crystals, so that fine Ti-containing oxide crystals can be precipitated and dispersed in the alumina crystals.

When Mg is further added, heat treatment is first performed in an oxidizing atmosphere to replace Ti ⁴⁺ and Mg ²⁺ with two Al ^3+, whereby Ti and M 2 are added.
g can be dissolved in alumina crystals.

Further, after the above-mentioned Ti and Mg are dissolved, a heat treatment is carried out in a reducing atmosphere, so that T
The valence of i changes from 4+ to 3+, and by replacing Ti ³⁺ with Al ³⁺ , Mg dissolved together with Ti is precipitated and dispersed in alumina crystals in the form of MgAl ₂ O _4. Can be.

The above heat treatment is preferably performed at a temperature in the range of 1200 ° C. or more in order to obtain a sufficiently high amount of solid solution when the above-mentioned elements are solid-dissolved. From the viewpoint of suppressing the increase of the crystal and the grain growth of the precipitated crystal, it is desirable to perform the heat treatment in a temperature range of 1100 ° C to 1500 ° C. Further, in the present invention, the reducing atmosphere means, for example, an atmosphere in which a hydrogen-containing gas, an inert gas, or the like is flown or an oxygen partial pressure such as vacuum is 10 ⁻⁶ atm or less. For example, an atmosphere having an oxygen partial pressure of 10 ⁻² atm or more in the atmosphere or the like.

On the other hand, Zr, Hf, 3
The element of the group a element reacts with alumina and other additives and unavoidable impurities to form a small amount of glass phase or crystal, and exists at the grain boundary of the alumina crystal.

[0028]

(Example 1) TiO ₂ powder having an average particle diameter of 0.7 μm, Mg (OH) ₂ powder having an average particle diameter of 0.6 μm, and alumina powder having an average particle diameter of 0.5 μm were added to alumina powder having an average particle diameter of 0.5 μm. 0.0μ
and Y ₂ O ₃ powder of m, additives and ZrO ₂ powder and HfO ₂ powder so that the ratio shown in Table 1, were mixed, 1 ton / cm
After press-molded at ^2, cold isostatic pressing and molding at a pressure of 3 ton / cm ^2, the relative density was obtained 98% of the sintered body was fired under the conditions shown in Table 1.

With respect to the obtained sintered body, the lattice constant of alumina was measured by X-ray diffraction to confirm whether or not a solid solution was formed. Further, the three-point bending strength was measured based on JISR1601. Furthermore, in the pin-on-disk method, a pin and a disk are manufactured in the same manner as the sintered body,
The wear volume and wear coefficient of the disk were measured under the conditions of a load of 1 kg, a rotational speed of the disk of 0.1 m / s, and 24 hours.

As a comparative example, a partially stabilized zirconia ceramic containing 3% Y ₂ O ₃ was prepared and evaluated in the same manner as in the examples. The results are shown in Table 1 (Sample No.
20).

[0031]

[Table 1]

[0032] As apparent from Table 1, the samples containing no TiO ₂ No. Sample No. 1 which was fired in the air after adding TiO ₂ and TiO ₂ . In Sample No. 17, no solid solution was formed in the alumina crystals, and the content of TiO ₂ was less than 0.5% by weight. 2, the effect of adding TiO ₂ is small,
All had low bending strength and wear resistance.
Further, the sample N having a TiO ₂ content of more than 10% by weight was used.
o. In No. 10, although a solid solution was formed in the alumina crystal, a large amount of Al ₂ TiO ₅ was precipitated at the alumina crystal grain boundary, and the bending strength and wear resistance were reduced. In addition, 3% Y ₂
Sample No. 1 consisting of partially stabilized zirconia ceramics containing O ₃ No. 20 had high bending strength but low wear resistance.

On the other hand, the sample N within the scope of the present invention
o. In the case of 3 to 9 and 11 to 16, the bending strength was 600 MPa or more, the abrasion volume was 20 × 10 ⁻³ mm ³ or less, and the friction coefficient was 0.1 MPa.
8 or less, indicating excellent wear resistance.

(Example 2) The samples obtained by adding MgO to the ceramic raw materials shown in Table 2
For the sample to which O was not added, while flowing hydrogen gas,
A sample was prepared and evaluated in the same manner as in Example 1, except that after baking at 1500 ° C. for 2 hours, baking was performed under the baking conditions shown in Table 2. The results are shown in Table 2.

[0035]

[Table 2]

[0036] than the results in Table 2, the samples containing no TiO ₂ No. In No. 19, Ti did not form a solid solution in the alumina crystal phase in the alumina crystal, no Ti-containing oxide crystal was precipitated, and the content of TiO ₂ was 0.5% by weight.
Less sample no. Even in No. 20, the effect of adding TiO ₂ was small, and both had low flexural strength and abrasion resistance. Further, the sample No. having a TiO ₂ content of more than 10% by weight. At 28, solid solution and T
Although i-containing oxide crystals were precipitated, a large amount of Al ₂ TiO ₅ was precipitated at the alumina crystal grain boundaries, and the bending strength and wear resistance were reduced.

On the other hand, the sample N within the scope of the present invention
o. For 21-27 and 29-34, bending strength 700MP
a, the wear volume was 17 × 10 ⁻³ mm ³ or less, and the friction coefficient was 0.7 or less, indicating excellent wear resistance.

Therefore, it was found that a biological member having excellent wear resistance can be produced by using the alumina ceramics within the scope of the present invention.

[0039]

As described in detail above, according to the present invention,
Abrasion resistance can be enhanced by using a ceramic in which a predetermined amount of TiO ₂ is added to form a solid solution in alumina crystals as a living body member. It is possible to manufacture a joint member that is unlikely to cause cracks. In addition, TiO ₂ or Mg
Precipitating and dispersing microcrystals of O, and Z
By precipitating an oxide crystal containing at least one of r, Hf, and 3a group elements, the strength of the ceramic can be increased, and the risk of damage to the biological member can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an artificial hip joint which is an application example of the ceramic biological member of the present invention.

[Explanation of symbols]

 Reference Signs List 1 artificial hip joint 2 stem 3 head 4 socket

Claims (6)

[Claims] 1. The method according to claim 1, wherein at least Ti is 0.5 to TiO ₂ equivalent.
A ceramic biomaterial made of alumina ceramics containing 10% by weight and part or all of Ti dissolved in alumina crystals. (2) containing 5% by weight or less of Mg in terms of MgO;
2. The ceramic biomaterial according to claim 1, wherein part or all of Mg is dissolved in the alumina crystal. 3. The ceramic biomaterial according to claim 1, wherein 0.5% by volume or more of Ti-containing oxide crystals are precipitated and dispersed in the alumina crystals. 4. The ceramic biomaterial according to claim 2, wherein 0.5% by volume or more of Mg-containing oxide crystals are precipitated and dispersed in said alumina crystals. 5. The method according to claim 1, wherein Zr, Hf,
The ceramic biomaterial according to any one of claims 1 to 4, wherein an oxide crystal containing at least one of Group 3a elements is dispersed. 6. The ceramic biological member according to claim 1, which is used as an artificial joint member.