EP3145894A1

EP3145894A1 - Bioceramic component

Info

Publication number: EP3145894A1
Application number: EP15724240.5A
Authority: EP
Inventors: Karl BILLAU; Gundula Kiefer; Wolfgang Burger
Original assignee: Bbl Technology Transfer & Co KG GmbH; Bbl Tech Transfer & Co KG GmbH
Current assignee: Bbl Technology Transfer & Co KG GmbH
Priority date: 2014-05-19
Filing date: 2015-05-18
Publication date: 2017-03-29
Also published as: RU2016149516A3; WO2015177089A1; RU2016149516A; RU2684551C2; EP2947061A1; EP2947061B1

Abstract

The invention relates to a bioceramic component that is produced at least in part from ceramic material with the following composition: - 55 - 90 vol% of an aluminum oxide matrix, - wherein 10 - 75 vol% of the aluminum oxide matrix is formed as hexagonal wafers of the chemical composition LaAI11O18, - 10 - 45 vol.-% of zirconium dioxide which is coated with a fraction of 0.5 - 2.5 mol% yttrium oxide relative to the zirconium dioxide, and stabilized by 2 - 10 mol% cerium oxide relative to the zirconium oxide, - 0.1 - 1.0 vol% Pr6O11, which forms a mixed crystal with the aluminum oxide and together with cerium oxide acts as bridge-forming oxide between the aluminum oxide and the zirconium dioxide, wherein in the composition of the ceramic component the fraction of aluminum oxide and of zirconium oxide together with the respective other components of the composition add up to 100% other than inevitable impurities.

Description

Bioceramic component

The invention relates to a bioceramic component, which is at least partially made of ceramic material with an aluminum oxide matrix and zirconium dioxide, and to a method for producing such a bioceramic component.

Bioceramic components of this type, namely artificial prostheses such. As hip joint implants or knee joint implants, are given in WO 2011/083 023 A1 (EP 2 513 010 A1). The composition of the ceramic material described therein comprises dispersed zirconium oxide, the tetragonal modification preferably being obtained by mechanical stabilization. In contrast, chemical stabilizers such as yttrium oxide Y2O3 are considered disadvantageous because of the associated hydrothermal aging. A requirement for the mechanical stabilization is an alumina content of at least 65% by volume and a zirconium oxide content of 10 to 35% by volume. Furthermore, EP 0 542 815 B1 describes a ceramic material which has become established in the market. The composition of these known zirconia and platelet-reinforced ceramics comprises a proportion of 60 to 98% by volume of an aluminum-chromium mixed-crystal-based matrix, which accounts for 67.1 to 99.2% by volume of an Al ₂ O 3. Cr ₂ O 3 mixed crystal and a proportion of 0.8-32.9% by volume SrAl _12x Cr _x O ₁₉ (x = 0.0007 to 0.045), the composition furthermore having a content of 2-40% by volume tetragonal zirconium which is stabilized with 0.2-3 mol% yttrium or 10-15 mol% CeO ₂ , Pr ₆ On Tb ₂ 0 ₃ . DE 198 50 366 A1 likewise describes a platelet-reinforced sintered ceramic material having a composition as described in EP 0 542 815 B1. However, platelet formation is based on different oxides.

WO 2008/040 813 A1 has a ceramic material as its content, which has a zirconium dioxide matrix, the zirconium dioxide being mixed-stabilized. In this document, reference is made to the aforementioned EP 0 542 815, which, however, teaches a ceramic with an alumina matrix wherein the alumina forms a solid solution with chromium oxide. It is also expressed here that the addition of cerium oxide, praseodymium oxide, terbium oxide or yttrium oxide exclusively serves as stabilizing oxides for the zirconium dioxide.

WO 2011/000 390 A1 proposes mixed stabilization of zirconium dioxide with yttrium oxide and cerium oxide. Also in this case, the ceramic (as in the aforementioned WO 2008/040 813 A1) is always based on a stabilized zirconium dioxide matrix, the matrix containing 50-75% by weight of the total composition. tion. As the third phase of the ceramic composition, an alkaline earth aluminate or LaAlnOi _{8 is} mentioned. Praseodymium oxide is not mentioned.

In US 2012/308 837 A1, the production of 3D components via a printing process is described, wherein the 3D component is built up in layers with typical layer thicknesses of 15-30 μιη. In this case, the alternating application of yttria-stabilized zirconia and a mixture of alumina and zirconia is proposed. In the journal article Jin X et al., "Effects of powder preparation method on the microstructure and mechanical performance of ZTA / LaAlnOis composites" JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, vol. 24, 1 April 2004 (2004- 04-01), pages 653 -659, producing a ZTA ceramic (alumina matrix ceramic-dispersed zirconia) with LaAlnO is written ₁₈ platelets loading. the preparation of the powder mixture based on the fact that an alumina suspension with salts is offset from the alloy components, the compression takes place by the hot pressing method. It is stated that the zirconia undergoes no phase transformation, it is mentioned an increase in strength without changing the fracture toughness, but in particular, a high fracture toughness is also essential for bioceramic components.

The journal articles IPEK Akin et al., "Effect of CeO ₂ addition on densification and microstructure of AI ₂ O ₃ -YSZ composites", CERAMICS INTERNATIONAL, vol. 37, no. 8, 23 May 2011 (2011-05-23), pages 3273-3280, and, F. Kern: "Effect of In-Formed Cerium Hexaaluminates Precipitates on Properties of Alumina -24 Vol% Zirconia (1.4Y) Composites", JOURNAL OF CERAMIC SCIENCE AND TECHNOLOGY, vol.4, no 4, 5 August 2013 (2013-08-05), pages 177-186, deals with the Material system of alumina-yttrium-stabilized zirconia and the addition of cerium oxide and the sintering in a reducing atmosphere. In both works, the formation of the CeAlnOi ₈ phase is described by the application of a reducing atmosphere. In the second mentioned document mentions that for the formation of the CeAlnOi ₈ phase a hot pressing temperature of 1425 ° C is not sufficient. There is no talk of mixed crystal formation.

EP 2 684 555 A2 proposes a glass or a glass ceramic which contains inter alia aluminum oxide and rare earth oxides or yttrium oxide. These oxides are incorporated in a glass or a glass ceramic, with boron oxide, germanium oxide, phosphorus pentoxide, silicon dioxide, tellurium oxide and vanadium pentoxide being used as the glass former. The main goal is to generate an amorphous phase. The object of the present invention is to provide bioceramic components which have improved material stability.

The object is achieved with the features of claims 1 and 1 1. Here, the bioceramic component is at least partially made of ceramic material, which has the following composition:

55-90% by volume of an alumina matrix,

wherein 10 to 75% by volume of the alumina matrix are formed as hexagonal platelets of the chemical composition LaAlnOis,

10 to 45% by volume of zirconium dioxide, which is replaced by yttrium oxide in a proportion of 0.5 to 2.5 mol%, based on the zirconium dioxide and by cerium oxide in one

Proportion of 2 - 10 mol% based on the zirconia is stabilized, 0.1-1.0% by volume of Pr ₆ On, which forms a mixed crystal with the aluminum oxide and, together with cerium oxide, acts as a bridging oxide between the aluminum oxide and zirconium dioxide,

wherein in the ceramic material, the proportion of alumina and zirconia together with the relevant bridging oxide comprising further

Components of the composition to complement unavoidable impurities to 100%.

The method for producing such a bioceramic component is characterized by the production steps:

Providing a ceramic material having the following composition:

55-90% by volume of an alumina matrix,

wherein 10 to 75 vol.% of the alumina matrix are formed as hexagonal platelets of the chemical composition LaAlnO-is,

From 10 to 45% by volume of zirconia stabilized by yttria in a proportion of 0.5 to 2.5 mol% based on the zirconia and by ceria in a proportion of 2 to 10 mol% relative to the zirconia, 0.1-1.0% by volume of Pr ₆ On, which forms a mixed crystal with the aluminum oxide and, together with cerium oxide, forms bridges between the oxide

Alumina and zirconia are effective,

wherein in the composition of the ceramic material, the proportion of alumina and zirconia together with the relevant, the bridging oxide comprising constituents of the composition to complement unavoidable impurities to 100%.

There are different approaches for the production of the ceramic material from the powder mixture in that these pressed (as part steps) and sintered or plasticized, sprayed, debindered and sintered. The final shape of the bioceramic component is finally adjusted via a grinding and polishing process. Advantageous embodiments with particularly advantageous ranges of the composition of the ceramic material are specified in claims 2 to 9.

Particular bioceramic components are the subject of claim 10.

In the method, it is advantageously provided that the step of producing the ceramic material comprises as substeps:

Preparing the powder mixture;

Pressing the powder mixture into a compact;

mechanical processing of the compact to a near-net shape blank;

Pre-sintering the blank until a closed porosity is achieved;

hot isostatic re-densification of the pre-sintered body;

Temperature treatment of the densified body and

subsequent grinding and polishing to the finished bioceramic component.

In the composition of the ceramic material specified in claim 1, the proportion of alumina and zirconia with its constituents including the bridging oxide add up to 100 vol .-%, except for unavoidable impurities. So if z. For example, if a proportion of 1.0% by volume of praseodymium oxide is used, the proportions of zirconium dioxide and of aluminum oxide matrix are chosen such that (with the exception of the unavoidable impurities) 100% by volume results, said range boundaries forming the outer frame , The upper limit of the The proportion of aluminum oxide and / or of zirconium oxide is thus reduced in accordance with the proportion of Pr ₆ On added, so that the addition is 100% complied with. The composition having the chemical stabilization and bridge-forming oxide taught in claim 1 gives bioceramic components of high stability, which in particular also have high resistance to moisture and temperature. The stability is enhanced by the added ceria, which stabilizes the metastable zirconia phase and forms anisotropic crystals with alumina, the process being directed at the formation of the crystallites.

As indicated in the dependent claims 2 to 9, the proportion of the matrix in the form of hexagonal platelets of the composition LaAlnO-ts is advantageously 20-60% by volume, in particular 33-50% by volume; the proportion of stabilizing yttrium oxide is advantageously 1 to 2 mol%, in particular 1, 5 to 1, 8 mol%; the proportion of stabilizing cerium oxide is advantageously from 2.5 to 6 mol%, in particular from 3 to 5 mol%; and the proportion of Pr ₆ On advantageously 0.2 to 0.8 vol .-%, in particular 0.25 to 0.5 vol .-%.

Hereinafter, a bioceramic component will be described as an exemplary embodiment. Fig. 1 shows a bioceramic component, a ball head 1, which can be used as part of a ball joint.

The ball head 1 is compatible with biological tissue (biocompatible) and has a spherical portion 10, which is to fit accurately into a ball socket of a joint of a patient. In the inner region of the ball head 1, a hollow receiver 11 is formed to insert and fix therein an outwardly projecting member. The ball head 1 is made of a ceramic material having the above-described composition. The surface 10 is polished and gives permanently stable, very good sliding properties. The receptacle 11 is formed so that it ensures a stable connection with the protruding part inserted therein, including z. B. a screw, adhesive connection and / or a cementing is used (come).

The preparation of the ceramic material having the stated composition and the bioceramic component produced therefrom comprises as essential steps: dispersing the constituents in water

Grinding and mixing in a stirred ball mill

Addition of a binder

Spray-drying the suspension

Pressing the powder mixture

Processing of the compact by cutting or cutting processes in order to obtain a blank in the form approximated to the final component,

Pre-sintering of the compact to closed porosity (with approximately 95-96 vol% of theoretical density)

hot isostatic pressing of the presintered compact until a practically complete final compaction is achieved,

Temperature treatment of the compacted body,

Grind and polish the post-compacted body until the final component contour is achieved.

The ceramic material is therefore provided that the composition of the ceramic material by mixing aluminum oxide Al ₂ O ₃ , zirconium dioxide ZrO ₂ , yttrium oxide Y ₂ O ₃ , cerium oxide CeO ₂ , lanthanum oxide La ₂ O ₃ and praseodymium Pr ₆ On in corresponding proportions to the powder mixture and by subsequent sintering is produced. After sintering, an alumina matrix in a proportion of 55-90% by volume and zirconium dioxide in a proportion of 10-45% by volume are present in the finished material, the zirconium dioxide being at least 75% by volume in the finished material. % is in its tetragonal modification and is chemically stabilized by a mixture of yttria and ceria.

A proportion of 10 to 75% by volume of the aluminum oxide matrix is in the form of hexagonal platelets of the composition (Ce, La) -AlnOie (cerium or lanthanum aluminate). The ceria is preferably in its tetravalent oxidation state and acts as a stabilizer oxide for the zirconia through the formation of a solid solution. Part of the cerium oxide may also be in its trivalent oxidation state. This then forms (Ce, La) -aluminate in the form of anisotropic hexagonal platelets. By alloying 0.1 to 1.0% by volume of P 2 O 1 based on the total mixture (overall composition), a corresponding mixed crystal is formed during sintering, preferably with the aluminum oxide matrix, specifically by chemical reaction with the aluminum oxide and praseodymium oxide. On the other hand, praseodymium oxide can also form a mixed crystal with zirconium dioxide by a solid-state chemical reaction. The preferred embodiment of the Al ₂ O ₃ : Pr mixed crystal takes place at relatively high temperatures (1450-1550 ° C.). The mixed crystal formation of Y ₂ O ₃ -CeO ₂ -ZrO ₂ '.Pr, however, takes place already at temperatures between 1390-1480 ° C.

Due to this effect, Pr ₆ On acts as a bridging agent for the consistent cohesion of the alumina / zirconia composite with increased fracture toughness.

The chemical composition of the powder mixture consists of the following educts: 55 - (approximately) 90 vol.% Al ₂ O ₃

10 - (approximately) 45% by volume Zr0 ₂

Y ₂ O ₃ and CeO ₂ (as a stabilizer for metastable tetragonal

Zr0 ₂ or Ce0 ₂ to form a mixed crystal or

CeO ₂ potentially for the training of

CeAliiOis or possibly also as a mixed crystal former, if it is present in low concentrations),

La ₂ 0 ₃ (to form LaAlnO-i ₈ )

Pr ₆ On (to form a mixed crystal with Al ₂ O ₃ or ZrO ₂ )

During the sintering process, the following chemical reactions take place:

11 Al ₂ 0 ₃ + La ₂ O ₃ -> LaAln0 ₁₈

ZrO ₂ + Y ₂ O ₃ + CeO ₂ - »ZrO ₂ : Y, Ce

11 AI ₂ 0 ₃ + Ce0 ₂ - + CeAliiOie

Al ₂ O ₃ + ZrO ₂ + Pr ₆ On -> Al ₂ O ₃ : Pr + ZrO ₂ : Pr

(With the notation Zr0 ₂ : Y, Ce the formation of a mixed crystal is expressed, whereas the formation of crystallographically defined phases is expressed in each case by the formula.)

In particular, the formation of the mixed crystal by the chemical reaction of Pr ₆ On and Al ₂ O ₃ or ZrO ₂ or the lanthanum aluminate is essential.

The chemical mixed stabilization results in the said composition high resistance. This is further enhanced by the fact that the alloyed ceria stabilizes both the metastable zirconia phase and simultaneously but also anisotropically formed crystallites with alumina forms, the process management is aligned with this formation of the crystallites.

In the process, it is provided that a homogeneous powder mixture of yttrium- and cerium oxide-coated zirconia grains, alumina, lanthanum oxide and praseodymium oxide is prepared by a Mischmahlung in water in a stirred ball mill, after which in a further step after addition of a binder system, the aqueous powder dispersion a spray-drying process is subjected.

For advantageous properties of the ceramic material, the measures contribute that the maximum proportion of yttria in the range of 0.5 to 2.5 mol% and the proportion of cerium oxide in the range between 2 to 10 mol% based on the zirconia.

The resistance of the ceramic material is favored by the fact that the proportion of hexagonal platelets is in the range of 20-60% by volume, in particular 33-50% by volume, of the aluminum oxide matrix. Further advantages result from the fact that the maximum proportion of yttrium oxide is in the range from 1.0 to 2.0 mol%, in particular from 1.5 to 1.8 mol%, based on the zirconium dioxide, and furthermore in that the maximum proportion of cerium oxide is in the range from 2.5 to 6 mol%, in particular from 3 to 5 mol%, based on the zirconium dioxide.

Significant advantages are further achieved in that the proportion of alloying of Pr ₆ O in the range of 0.2 to 0.8 vol .-%, in particular from 0.25 to 0.5 vol .-%, is. In the process, depending on the requirements of the bioceramic Component be provided that the spray granules obtained from the spray-drying process is compressed directly or plasticized with the addition of organic polymers and then processed by injection molding to form the bioceramic component.

The preparation of the powder mixture takes place via the mixed grinding, followed by a spray-drying process. Either the spray granules are pressed directly or plasticized with the addition of organic polymers and then processed by injection molding to the bioceramic component.

By the mixed stabilization, the phase transformation of tetragonal ZrO 2 to monoclinic phase, which z. B. can be induced by hydrothermal treatment or mechanical processing, largely prevented. This counteracts dimensional changes or eliminates them.

Some compositions of the novel ceramic materials are reproduced in the following table with relevant parameters, wherein also two comparative examples are mentioned.

Claims

1. Bioceramic component, which is at least partially made of ceramic material, which has the following composition:

55-90% by volume of an alumina matrix,

wherein 10 to 75% by volume of the alumina matrix are formed as hexagonal platelets of the chemical composition LaAlnOis or (Ce, La) -AlnOi ₈ ,

10 to 45% by volume of zirconium dioxide which is stabilized by yttrium oxide in a proportion of 0.5 to 2.5 mol% based on the zirconium dioxide and by ce- oxide in a proportion of 2 to 10 mol%, based on the zirconium dioxide is

0.1 - 1, 0 vol .-% Pr ₆ On, which forms a mixed crystal with the alumina and acts together with ceria as a bridging oxide between the alumina and zirconia, wherein in the composition of the ceramic material, the proportion of alumina and zirconia together with the other constituents of the composition in question, with the exception of unavoidable impurities, which add up to 100%.

2. Bioceramic component according to claim 1,

characterized,

that 20-60% by volume of the alumina matrix are formed as hexagonal platelets LaAl Oi8.

3. Bioceramic component according to claim 1 or 2,

characterized, that 33-50 vol.% of the alumina matrix are formed as hexagonal platelets LaA iOi8.

Bioceramic component according to one of the preceding claims, characterized

the maximum proportion of stabilizing yttrium oxide is 1 to 2 mol%.

Bioceramic component according to one of the preceding claims, characterized

the maximum proportion of stabilizing yttrium oxide is 1, 5 - 1, 8 mol%.

Bioceramic component according to one of the preceding claims, characterized

the maximum amount of stabilizing cerium oxide is 2.5-6 mol%.

Bioceramic component according to one of the preceding claims, characterized

the maximum amount of cerium oxide is 3 - 5 mol%.

Bioceramic component according to one of the preceding claims, characterized

that the maximum proportion of P ^ O-H is 0.2 to 0.8% by volume.

Bioceramic component according to one of the preceding claims, characterized

the maximum proportion of P ^ On is 0.25-0.5% by volume.

0. Bioceramic component according to one of the preceding claims, characterized in that

that it is designed as a knee joint prosthesis, hip joint prosthesis, shoulder joint prosthesis, finger joint prosthesis or as a prosthesis of a leg or arm leg.

1. A method for producing a bioceramic component of the structure specified in claim 1,

characterized by the manufacturing steps:

Providing a powder mixture and producing a ceramic material from the same, which has the following composition:

55-90% by volume of an alumina matrix,

wherein 10 to 75 vol.% of the alumina matrix are formed as hexagonal platelets of the chemical composition LaAlnO-is, 10 to 45 vol.% zirconia, which is based on yttria in a proportion of 0.5 to 2.5 mol% the zirconium dioxide is stabilized by ce- oxide in a proportion of 2 to 10 mol% with respect to the zirconium dioxide,

0.1-1.0% by volume of Pr ₆ On, which forms a mixed crystal with the aluminum oxide and, together with cerium oxide, acts as a bridging oxide between the aluminum oxide and zirconium dioxide,

wherein in the ceramic material, the proportion of alumina and zirconia together with the relevant other constituents of the composition add up to unavoidable impurities to 100%, and

Making the final shape of the part through a grinding and polishing process. 12. The method according to claim 11,

characterized,

the production of the ceramic material from the powder mixture as partial steps comprises pressing and sintering of the powder mixture.

13. The method according to claim 12,

characterized,

in that the step of producing the ceramic material comprises as substeps:

Providing the powder mixture;

Pressing the powder mixture into a compact;

mechanical processing of the compact to a blank;

Pre-sintering the blank until a closed porosity is achieved; hot isostatic re-densification of the pre-sintered body;

Temperature treatment of the densified body and subsequent grinding and polishing to the finished bioceramic component

in the order named with or without intermediate steps.

14. The method according to claim 11,

characterized in that the production of the ceramic material from the powder mixture as part steps comprises plasticizing, spraying, debinding and sintering.

15. The method according to claim 11 or 14,

characterized, that the step of producing the ceramic material comprises as substeps:

Providing the powder mixture;

Debinding and plasticizing the powder mixture;

- Injection molding of the desired component in a mold

Debinding and pre-sintering of the blank until a closed porosity is achieved

hot isostatic re-densification of the pre-sintered body;

Tempeaturbehandlung the post-compacted body and

Subsequent grinding and polishing to the finished bioceramic

component

in the order named with or without intermediate steps.