JP4931298B2 - Manufacturing method of artificial joint made of high-strength zirconia sintered body - Google Patents
Manufacturing method of artificial joint made of high-strength zirconia sintered body Download PDFInfo
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- JP4931298B2 JP4931298B2 JP2001229700A JP2001229700A JP4931298B2 JP 4931298 B2 JP4931298 B2 JP 4931298B2 JP 2001229700 A JP2001229700 A JP 2001229700A JP 2001229700 A JP2001229700 A JP 2001229700A JP 4931298 B2 JP4931298 B2 JP 4931298B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、アルミナを含有した高強度ジルコニア質焼結体に関するものである。
【０００２】
【従来の技術】
従来、セラミック部材の中でも耐摩耗性、耐熱性、耐薬品性等の点で優れた特性を有するとともに、圧倒的に安価でかつ工業的に有用な材料としてアルミナ質焼結体が使用されており、例えば、ディスクバルブ、ベアリングボール、ベーンポンプのベーン、プランジャーポンプのプランジャーロッド等の摺動部材や粉砕部材、また切削、研磨工具、さらには生体用補綴部材など様々な用途で使用されている。
【０００３】
しかしながら、アルミナ質焼結体は上述のような優れた特性を有する反面、ジルコニア質焼結体や窒化珪素質焼結体などの他のセラミック焼結体に比べて抗折強度が低いことから、高い応力のかかる部分に安定して使用することができなかった。
【０００４】
そこで、高強度材料としてジルコニア質焼結体が用いられることがあり、特に、抗折強度が必要な用途には、アルミナを含有した高強度ジルコニア質焼結体が用いられている。ジルコニア結晶粒子のマトリックス中に数十重量％（２０〜４０％）のアルミナ結晶粒子を分散させるとより高強度な複合体が得られる。これはマイクロクラックに対してジルコニア結晶粒子が正方晶から単斜晶へ変態することと、ジルコニアとアルミナの熱膨張係数のミスマッチによる残留応力が存在することでマイクロクラックが効果的に遮蔽されるためであると考えられる。通常のジルコニア質焼結体でもその抗折強度は最大で１４００ＭＰａ程度であり、これに対して工業的に利用されているアルミナを含有した高強度ジルコニア質焼結体の抗折強度は１８００ＭＰａ程度であった。因みに、上記アルミナを含有した高強度ジルコニア質焼結体においてアルミナ結晶粒子の平均粒径はジルコニア結晶粒子の平均粒径よりかなり大きく、ジルコニア結晶粒子の平均粒径に比べて２倍以上の平均粒径であった。
【０００５】
【発明が解決しようとする課題】
しかしながら、例えば、人工股関節の骨頭部材のように非常に大きな応力受ける部位に用いるジルコニア質焼結体としては、より大きな抗折強度を持った高強度ジルコニア質焼結体が望まれている。それは、ジルコニアは生体内で用いても生体組織に対する毒性がほとんどない生体材料だからである。生体用としては、概ね２０００ＭＰａを超える抗折強度であれば、生体内高荷重部位で使用しても破壊の恐れがほとんどなくなる。
そこで、本発明はジルコニア質焼結体の抗折強度を飛躍的に向上させることを目的とするものである。
【０００６】
【課題を解決するための手段】
上記従来技術の課題を解決するため本発明の高強度ジルコニア質焼結体からなる人工関節の製造方法は、ジルコニアを主成分とし、アルミナを１５〜４５重量％の割合で含有し、かつジルコニアの全結晶相のうち正方晶と立方晶の結晶相が９０％以上を占めるとともに、前記焼結体中のジルコニア結晶粒子のみの平均粒径とこのジルコニア結晶粒子と前記アルミナ結晶粒子とを合わせた全体の平均粒径との比が０．９５〜１．００であり、かつ上記ジルコニア結晶粒子の平均粒径が０．２５μｍ以上であり、抗折強度が２０００ＭＰａ以上である高強度ジルコニア質焼結体からなる人工関節の製造方法であって、前記ジルコニアとイットリアとの混合粉末およびアルミナの粉末を混合して原料粉末を得る工程、前記原料粉末に水を添加して混練乾燥することにより造粒体を得る工程、および前記造粒体を冷間静水圧成形法により成形し、１９０ＭＰａ以上の圧力で高温静水圧焼成する工程を包含する。かかる構成によれば、アルミナの含有率が１５〜４５重量％のジルコニア質焼結体において平均粒径を上記範囲に設定したので、ジルコニア質焼結体に高い抗折強度をもたらす応力誘起変態を起こそうとするジルコニア結晶粒子のエネルギーが高くなる一方で、これを阻害しようとするアルミナ結晶粒子のエネルギーが低くなる。したがって上記応力誘起変態が起こりやすい組織状態であるので、抗折強度が非常に大きい。ジルコニア結晶粒子の平均粒径が０．２５μｍ未満のとき、結晶粒子の表面積が小さく、上記応力誘起変態を起こそうとするジルコニア結晶粒子のエネルギーが不十分となる。また前記焼結体中のジルコニア結晶粒子のみの平均粒径とこのジルコニア結晶粒子と前記アルミナ結晶粒子とを合わせた全体の平均粒径との比が０．９５以下のとき、上記応力誘起変態を起こそうとするジルコニア結晶粒子のエネルギーに対して、これを阻害しようとするアルミナ結晶粒子のエネルギーが大きくなり、十分な応力誘起変態が起こりにくくなる。これに対して、前記焼結体中のジルコニア結晶粒子のみの平均粒径とこのジルコニア結晶粒子と前記アルミナ結晶粒子とを合わせた全体の平均粒径との比が１．００より大きいとき、アルミナとジルコニアの熱膨張係数の違いにより無視できない内部応力（アルミナは圧縮応力、ジルコニアは引っ張り応力）が発生する。そして、引っ張り応力過多となり、その結果、抗折強度の低下につながる。なお、アルミナの含有率が１５重量％未満の場合、アルミナ結晶粒子の存在による残留応力の寄与が不十分となり抗折強度があまり向上しない。これに対して、アルミナ含有率が４５重量％より大きい場合、アルミナ結晶粒子の存在がジルコニア結晶粒子の応力誘起変態を抑える方向に働いてしまうため抗折強度があまり向上しない。
【０００７】
【発明の実施の形態】
以下、本発明の実施形態について詳述する。
【０００８】
本発明の高強度ジルコニア質焼結体（以下、ジルコニア質焼結体と略称する）は、ほぼ全体が正方晶と立方晶の結晶相を有する微細なジルコニア質焼結体中の粒界にアルミナを分散してなる。
上記焼結体中、ジルコニアの全結晶相のうち正方相と立方相の結晶相が９０％以上を占める。これは、正方晶と立方晶の結晶相が９０％未満であると、正方相ジルコニアが相変態したとしても、既存の単斜晶に存在するマイクロクラックにより、焼結体の抗折強度を向上させることが出来ないからである。
なお、正方晶と立方晶の結晶相の割合は、Ｘ線回折法にて測定することができる。すなわち、Ｘ線回折により単斜晶ジルコニアのピーク強度と正方晶ジルコニアと立方晶ジルコニアのピーク強度を測定し、数１に示す式から算出すれば良い。
【０００９】
【数１】
ところで、走査型電子顕微鏡（ＳＥＭ）による反射電子像を画像解析すると、アルミナ質焼結体中のジルコニア結晶粒子は白色に見え、アルミナ結晶粒子は黒色又は灰色に見える。なお、画像解析において、白色に見える結晶粒子がジルコニアであるかどうかは、波長分散型Ｘ線マイクロアナライザー分析（ＥＰＭＡ）により定性分析し、その元素を同定すれば良い。また、ジルコニア質焼結体に含まれるジルコニア結晶粒子の平均粒径を０．２５μｍ以上とし、かつ前記焼結体中のジルコニア結晶粒子のみの平均粒径とこのジルコニア結晶粒子と前記アルミナ結晶粒子とを合わせた全体の平均粒径との比を０．９５〜１．００とすることが重要である。これは、ジルコニア結晶粒子の平均粒径が０．２５μｍ未満であると、ジルコニア結晶粒子が小さくなり過ぎるためジルコニアの応力誘起変態が発生せず２０００ＭＰａを超える抗折強度を実現することができないからである。また、前記焼結体中のジルコニア結晶粒子のみの平均粒径とこのジルコニア結晶粒子と前記アルミナ結晶粒子とを合わせた全体の平均粒径（以下、焼結体の平均粒径という）との比が０．９５〜１．００の範囲外である場合、強度低下を招き２０００ＭＰａを超える抗折強度を得ることができない。次に、本発明に係る高強度ジルコニア質焼結体の製造方法について説明する。本発明に係る高強度ジルコニア質焼結体の原料は共沈法により得ることができる。原料粉末として、イットリア／ジルコニアのモル比が２／９８〜７／９３の範囲であることを特徴とする混合粉末と、アルミナの粉末を均質に混合した粉末を用いる。次に、得られた原料粉体に、溶媒及びバインダーを添加して混練乾燥することにより造粒体を作製し、この造粒体を一軸加圧成形法、泥しょう鋳込み法、等軸加圧成形法、射出成形法など通常のセラミック成形法により所定形状に成形した後、大気雰囲気中あるいは水素雰囲気中や窒素雰囲気中にて焼成する。この時、焼成温度が１３５０℃未満では、焼結性が不十分であるために緻密化することができず、１６５０℃より高くなると、粒成長を促進させてしまうため、いずれも得られたジルコニア質焼結体の抗折強度を２０００ＭＰａより高くすることができない。このため、焼成温度は１３５０℃〜１６５０℃の温度範囲とする。
【００１１】
次にガラスなどの高温で軟化するカプセルに封入し、高温静水圧焼成（以下、ＨＩＰ処理という）を行う。ＨＩＰ処理の条件は不活性雰囲気中で行い、温度は１２００℃〜１６００℃、圧力は１９０ＭＰａ以上が好ましい。
【００１２】
このとき、イットリアはジルコニア結晶粒子内に固溶し、ジルコニア結晶粒子の一部を構成する。
【００１３】
なお上記ＨＩＰ処理は、好ましくは１４７５℃〜１５７５℃の温度で行うことがよい。
【００１４】
以上、本発明の実施形態例を説明したが本発明はこの実施形態に限定されるものではない。発明の目的を逸脱しない限り任意の形態とすることができる。
【００１５】
例えば、材料組成として、イットリア、ジルコニア、アルミナ以外の任意のものを添加してもよい。その場合、ジルコニア結晶粒子及びアルミナ結晶粒子以外に結晶粒子があったとしても、その結晶粒子は平均粒子径の計測に含める必要はない。
【００１６】
【実施例】
（実施例）以下、本発明の具体例について説明する。
【００１７】
共沈法により表１に示す組成の原料粉末を得た。この原料粉体にバインダーと溶媒としての水を添加して混練乾燥することにより造粒体を作製し、該造粒体を型内に充填して冷間静水圧成形法により円柱状に成形した後、この成形体を１３５０℃〜１４５０℃の大気雰囲気中にて焼成し、さらに表１に示す温度によりＨＩＰ処理することにより、アルミナを含有してなるジルコニア質焼結体を得た。
【００１８】
【表１】
これらのジルコニア質焼結体の表面に研磨加工を施して中心線平均粗さ（Ｒａ）０．２μｍの鏡面に仕上げ、その表面の反射電子像を走査型電子顕微鏡にて撮影し、インターセプト法によりジルコニア結晶粒子の平均粒径とアルミナ結晶粒子の平均粒径、並びに焼結体の平均粒径とジルコニア結晶粒子の平均粒径の比を求めた。これらの結果を表１に示す。
ジルコニアの結晶状態について確認するため、Ｘ線回折により正方晶と立方晶ジルコニアのピーク強度と単斜晶ジルコニアのピーク強度をそれぞれ測定し、上記数１の式により正方晶と立方晶の結晶相の割合を測定したところ、９９．５％と、焼結体中におけるジルコニアの大部分が正方晶及び／又は立方晶のジルコニアであった。
【００２０】
さらに、ジルコニア質焼結体に切削加工を施して３ｍｍ×４ｍｍ×４０ｍｍの角柱体を製作し、ＪＩＳ Ｒ １６０１に準拠して、３点曲げ抗折強度を測定した。この結果を表１に示す。
【００２１】
表１に示すように本発明範囲内の試料３、４、８、９はすべて抗折強度２０００ＭＰａを超えている。
【００２２】
試料１、２、６、７、１１、１２、１３はジルコニア結晶粒子の平均粒径が０．２５μｍ未満であり、本発明の範囲から外れる。これら試料の抗折強度は１７００ＭＰａを下まわっていた。また、試料５、１０、１４、１６はジルコニア結晶粒子の平均粒径が０．２５μｍ以上であるものの、本発明範囲内のジルコニア結晶粒子の平均粒径と焼結体の平均粒径の比が０．９５〜１．００の範囲から外れていた。これらの試料も抗折強度１７００ＭＰａを下まわっていた。試料１５はジルコニア結晶粒子の平均粒径が０．２５μｍ以上で、かつジルコニア結晶粒子の平均粒径と焼結体の平均粒径の比が０．９５〜１．００の範囲内であったが、抗折強度１７００ＭＰａを上回ることはなかった。上記の結果から、ジルコニア質焼結体にアルミナを１５〜４５重量％含み、ジルコニアの平均粒径が０．２５μｍ以上であって、かつジルコニア結晶粒子の平均粒径と焼結体の平均粒径の比が０．９５〜１．００のときに非常に高い抗折強度が得られた。これにより従来工業的に使用されてきたジルコニア質焼結体では得られなかった２０００ＭＰａという非常に高い抗折強度を得ることが可能である。これに対して、本発明範囲外のものは抗折強度向上の十分な効果が見られなかった。
【００２３】
【発明の効果】
以上のように、本発明の高強度ジルコニア質焼結体によれば、アルミナの含有率が１５〜４５重量％のジルコニア質焼結体において結晶粒子の平均粒径を上記範囲に設定したので、ジルコニア質焼結体に高い抗折強度をもたらす応力誘起変態を起こそうとするジルコニア結晶粒子のエネルギーが高くなる一方で、これを阻害しようとするアルミナ結晶粒子のエネルギーが低くなる。したがって上記応力誘起変態が起こりやすい組織状態であるので、抗折強度が非常に大きい。例えば、人工関節の骨頭部材のような高負荷状況にさらされる箇所において信頼性よく使用することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-strength zirconia sintered body containing alumina.
[0002]
[Prior art]
Conventionally, among ceramic members, it has excellent characteristics in terms of wear resistance, heat resistance, chemical resistance, etc., and alumina sintered bodies have been used as overwhelmingly inexpensive and industrially useful materials. For example, it is used in various applications such as sliding members and grinding members such as disc valves, bearing balls, vanes of vane pumps, plunger rods of plunger pumps, cutting and polishing tools, and bioprosthetic members. .
[0003]
However, the alumina sintered body has excellent characteristics as described above, but has a lower bending strength than other ceramic sintered bodies such as a zirconia sintered body and a silicon nitride sintered body. It could not be used stably in a portion where high stress was applied.
[0004]
Therefore, a zirconia sintered body may be used as a high-strength material, and a high-strength zirconia sintered body containing alumina is used particularly for applications that require bending strength. When several tens weight% (20 to 40%) of alumina crystal particles are dispersed in a matrix of zirconia crystal particles, a higher strength composite can be obtained. This is because the microcracks are effectively shielded by the transformation of the zirconia crystal grains from tetragonal to monoclinic with respect to the microcracks and the presence of residual stress due to the mismatch between the thermal expansion coefficients of zirconia and alumina. It is thought that. Even a normal zirconia sintered body has a bending strength of about 1400 MPa at the maximum. On the other hand, a bending strength of a high-strength zirconia sintered body containing alumina that is industrially used is about 1800 MPa. there were. Incidentally, in the high-strength zirconia sintered body containing alumina, the average particle size of the alumina crystal particles is considerably larger than the average particle size of the zirconia crystal particles, and the average particle size is more than twice the average particle size of the zirconia crystal particles. It was a diameter.
[0005]
[Problems to be solved by the invention]
However, for example, a high-strength zirconia sintered body having a higher bending strength is desired as a zirconia sintered body used for a portion subjected to a very large stress, such as a bone head member of an artificial hip joint. This is because zirconia is a biomaterial that has almost no toxicity to living tissue even when used in vivo. For living organisms, if the bending strength exceeds approximately 2000 MPa, there is almost no risk of destruction even if it is used at a high load site in the living body.
Accordingly, the object of the present invention is to dramatically improve the bending strength of the zirconia sintered body.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems of the prior art, the method for producing an artificial joint comprising a high-strength zirconia sintered body according to the present invention comprises zirconia as a main component, alumina in a proportion of 15 to 45% by weight, and zirconia Of all the crystal phases, the tetragonal and cubic crystal phases occupy 90% or more, and the average particle size of only the zirconia crystal particles in the sintered body is combined with the zirconia crystal particles and the alumina crystal particles. the average particle diameter and a ratio of 0.95 to 1.00, and Ri der average particle diameter more than 0.25 micron m above the zirconia crystal grains, transverse rupture strength Ru der least 2000MPa high strength zirconia of a process for producing an artificial joint made of sintered, to obtain a raw material powder by mixing powder of the mixed powder and alumina and the zirconia and yttria, and adding water to the raw material powder mixed Obtaining a granule by drying, and the granular material was molded by cold isostatic pressing method, comprising the step of hot isostatic firing at pressures above 190 MPa. According to such a configuration, since the average particle diameter is set in the above range in the zirconia sintered body having an alumina content of 15 to 45% by weight, the stress-induced transformation that provides high bending strength to the zirconia sintered body is achieved. While the energy of the zirconia crystal particles to be raised is increased, the energy of the alumina crystal particles to be hindered is decreased. Therefore, since the stress-induced transformation is likely to occur, the bending strength is very high. When the average particle size of the zirconia crystal grains is less than 0.25 micron m, the surface area of the crystal grains is small, the energy of the zirconia crystal particles to be wake of the stress-induced transformation becomes insufficient. When the ratio of the average particle size of only the zirconia crystal particles in the sintered body to the total average particle size of the zirconia crystal particles and the alumina crystal particles is 0.95 or less, the stress-induced transformation is performed. The energy of the alumina crystal particles to inhibit this becomes larger than the energy of the zirconia crystal particles to be caused, so that sufficient stress-induced transformation is difficult to occur. On the other hand, when the ratio of the average particle size of only the zirconia crystal particles in the sintered body to the total average particle size of the zirconia crystal particles and the alumina crystal particles is larger than 1.00, alumina Internal stress (compressive stress for alumina and tensile stress for zirconia) is generated due to the difference in thermal expansion coefficient between zirconia and zirconia. And it becomes excessive tensile stress, As a result, it leads to the fall of bending strength. When the alumina content is less than 15% by weight, the contribution of residual stress due to the presence of alumina crystal particles is insufficient, and the bending strength is not improved so much. On the other hand, when the alumina content is higher than 45% by weight, the presence of alumina crystal particles works in a direction to suppress the stress-induced transformation of zirconia crystal particles, so that the bending strength is not improved so much.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0008]
The high-strength zirconia sintered body of the present invention (hereinafter abbreviated as zirconia sintered body) is made of alumina at a grain boundary in a fine zirconia sintered body having substantially a tetragonal crystal structure and a cubic crystal phase. Is distributed.
In the sintered body, the crystal phase of the tetragonal phase and the cubic phase occupy 90% or more of the total crystal phase of zirconia. This is because when the tetragonal and cubic crystal phases are less than 90%, even if the tetragonal zirconia undergoes phase transformation, the bending strength of the sintered body is improved due to the microcracks existing in the existing monoclinic crystals. It is because it cannot be made to do.
The ratio of tetragonal and cubic crystal phases can be measured by the X-ray diffraction method. That is, the peak intensity of monoclinic zirconia and the peak intensity of tetragonal zirconia and cubic zirconia may be measured by X-ray diffraction and calculated from the equation shown in Equation 1.
[0009]
[Expression 1]
By the way, when an image analysis of the reflected electron image by a scanning electron microscope (SEM) is performed, the zirconia crystal particles in the alumina sintered body appear white and the alumina crystal particles appear black or gray. In the image analysis, whether or not the crystal particles that appear white are zirconia may be qualitatively analyzed by wavelength dispersive X-ray microanalyzer analysis (EPMA) to identify the element. Further, the average particle diameter of the zirconia crystal particles contained in the zirconia sintered body is 0.25 μm or more, and the average particle diameter of only the zirconia crystal particles in the sintered body, the zirconia crystal particles and the alumina crystal particles, It is important that the ratio to the average particle diameter of the total of 0.95 is set to 0.95 to 1.00. This is because when the average particle size of the zirconia crystal grains is less than 0.25 [mu] m, since the stress induced transformation of zirconia for the zirconia crystal grains is too small can not be realized is exceeded the flexural strength of 2000MPa not occur It is. Further, the ratio between the average particle size of only the zirconia crystal particles in the sintered body and the total average particle size of the zirconia crystal particles and the alumina crystal particles (hereinafter referred to as the average particle size of the sintered body). If is outside the scope of 0.95 to 1.00, it is impossible to a 2000MPa lead to reduced strength obtain Exceeding bending strength. Next, the manufacturing method of the high intensity | strength zirconia sintered compact concerning this invention is demonstrated. Raw material of high strength zirconia sintered body according to the present invention is Ru can be obtained by coprecipitation. As the raw material powder, a mixed powder characterized in that the molar ratio of yttria / zirconia is in the range of 2/98 to 7/93 and a powder in which alumina powder is homogeneously mixed are used. Next, a granulated body is prepared by adding a solvent and a binder to the obtained raw material powder, followed by kneading and drying, and the granulated body is subjected to a uniaxial pressure molding method, a slurry casting method, and an equiaxed pressure. After forming into a predetermined shape by an ordinary ceramic forming method such as a forming method or an injection forming method, firing is performed in an air atmosphere , a hydrogen atmosphere, or a nitrogen atmosphere. At this time, if the firing temperature is less than 1350 ° C., it cannot be densified due to insufficient sinterability, and if it is higher than 1650 ° C., it promotes grain growth, so that all obtained zirconia The bending strength of the sintered material cannot be made higher than 2000 MPa. For this reason, a calcination temperature shall be the temperature range of 1350 to 1650 degreeC.
[0011]
Next, it is encapsulated in a capsule that softens at a high temperature such as glass and fired at a high temperature under isostatic pressure (hereinafter referred to as HIP treatment). The HIP treatment is performed in an inert atmosphere, and the temperature is preferably 1200 ° C. to 1600 ° C. and the pressure is preferably 190 MPa or more.
[0012]
At this time, yttria is dissolved in the zirconia crystal particles and constitutes a part of the zirconia crystal particles.
[0013]
The HIP treatment is preferably performed at a temperature of 1475 ° C to 1575 ° C.
[0014]
The embodiment of the present invention has been described above, but the present invention is not limited to this embodiment. Any form can be used without departing from the object of the invention.
[0015]
For example, any material composition other than yttria, zirconia, and alumina may be added. In that case, even if there are crystal particles other than zirconia crystal particles and alumina crystal particles, the crystal particles need not be included in the measurement of the average particle diameter.
[0016]
【Example】
EXAMPLES Examples of the present invention will be described below.
[0017]
Raw material powders having the compositions shown in Table 1 were obtained by the coprecipitation method. This raw material powder is mixed with a binder and water as a solvent and kneaded and dried to produce a granulated body. The granulated body is filled in a mold and molded into a cylindrical shape by a cold isostatic pressing method. Thereafter , the compact was fired in an air atmosphere at 1350 ° C. to 1450 ° C., and further subjected to HIP treatment at a temperature shown in Table 1 , thereby obtaining a zirconia sintered body containing alumina.
[0018]
[Table 1]
The surface of these zirconia sintered bodies is polished to give a mirror surface with a center line average roughness (Ra) of 0.2 μm, and a reflected electron image of the surface is taken with a scanning electron microscope, and intercepted. The average particle diameter of the zirconia crystal particles and the average particle diameter of the alumina crystal particles, and the ratio of the average particle diameter of the sintered body to the average particle diameter of the zirconia crystal particles were determined. These results are shown in Table 1.
In order to confirm the crystal state of zirconia, the peak intensity of tetragonal and cubic zirconia and the peak intensity of monoclinic zirconia are measured by X-ray diffraction, respectively. When the ratio was measured, 99.5%, and most of the zirconia in the sintered body was tetragonal and / or cubic zirconia.
[0020]
Furthermore, a 3 mm × 4 mm × 40 mm prismatic body was manufactured by cutting the zirconia sintered body, and the three-point bending strength was measured in accordance with JIS R 1601. The results are shown in Table 1.
[0021]
As shown in Table 1, all the samples 3, 4, 8, and 9 within the scope of the present invention exceed the bending strength of 2000 MPa.
[0022]
Samples 1 , 2 , 6, 7, 1 1 , 1 2 , 1 and 3 have an average particle diameter of zirconia crystal particles of less than 0.25 μm, and are out of the scope of the present invention. The bending strength of these samples was below 1700 MPa. In Sample 5, 10, 1 4, 1 6 although the average particle size of the zirconia crystal particles is 0.25μm or more, the average particle sizes of the sintered body of zirconia crystal grains within the scope of the invention The ratio was outside the range of 0.95 to 1.00. These samples also had a bending strength of less than 1700 MPa. Sample 1 5 with an average particle size of the zirconia crystal grains 0.25μm or more and the ratio of the average particle sizes of the sintered body of zirconia crystal grains is within the range of 0.95 to 1.00 However, the bending strength did not exceed 1700 MPa. From the above results, the zirconia sintered body contains 15 to 45% by weight of alumina, the average particle diameter of zirconia is 0.25 μm or more, and the average particle diameter of the zirconia crystal particles and the average particle diameter of the sintered body When the ratio was 0.95 to 1.00, a very high bending strength was obtained. As a result, it is possible to obtain a very high bending strength of 2000 MPa, which has not been obtained with zirconia sintered bodies that have been used industrially. On the other hand, those outside the scope of the present invention did not show a sufficient effect of improving the bending strength.
[0023]
【Effect of the invention】
As described above, according to the high-strength zirconia sintered body of the present invention, the average particle diameter of the crystal particles is set in the above range in the zirconia sintered body having an alumina content of 15 to 45% by weight. While the energy of the zirconia crystal particles that attempt to cause stress-induced transformation that brings high bending strength to the zirconia-based sintered body is increased, the energy of the alumina crystal particles that are intended to inhibit this is decreased. Therefore, since the stress-induced transformation is likely to occur, the bending strength is very high. For example, Ru can be used reliably in places which are exposed to high load conditions, such as bone head member of the prosthesis.
Claims (1)
前記焼結体中のジルコニア結晶粒子のみの平均粒径とこのジルコニア結晶粒子と前記アルミナ結晶粒子とを合わせた全体の平均粒径との比が０．９５〜１．００であり、かつ上記ジルコニア結晶粒子の平均粒径が０．２５μｍ以上であり、抗折強度が２０００ＭＰａ以上である高強度ジルコニア質焼結体からなる人工関節の製造方法であって、
前記ジルコニアとイットリアとの混合粉末およびアルミナの粉末を混合して原料粉末を得る工程、
前記原料粉末に水を添加して混練乾燥することにより造粒体を得る工程、
および前記造粒体を冷間静水圧成形法により成形し、１９０ＭＰａ以上の圧力で高温静水圧焼成する工程を包含することを特徴とする高強度ジルコニア質焼結体からなる人工関節の製造方法。The main component is zirconia, the alumina is contained in a proportion of 15 to 45% by weight, and the total crystal phase of zirconia accounts for 90% or more of tetragonal and cubic crystal phases,
The ratio of the average particle size of only the zirconia crystal particles in the sintered body to the total average particle size of the zirconia crystal particles and the alumina crystal particles is 0.95 to 1.00, and the zirconia der average particle diameter of more than 0.25 micron m of the crystal grains is, a process for producing an artificial joint bending strength made of a high strength zirconia sintered body Ru der least 2000 MPa,
Mixing raw powder of zirconia and yttria and alumina powder to obtain a raw material powder;
A step of obtaining granules by adding water to the raw material powder and kneading and drying;
And a method for producing an artificial joint comprising a high-strength zirconia sintered body, comprising a step of forming the granulated body by a cold isostatic pressing method and firing it at a high pressure hydrostatic pressure at a pressure of 190 MPa or more .
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| US7820577B2 (en) | 2003-10-30 | 2010-10-26 | Kyocera Corporation | Biomedical member and method for producing the same |
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| JP5036271B2 (en) * | 2006-10-16 | 2012-09-26 | 株式会社ニッカトー | Zirconia conductive sintered body |
| JP2011017415A (en) * | 2009-07-10 | 2011-01-27 | Nsk Ltd | Rolling bearing for turbocharger and method for manufacturing the same |
| JP5779878B2 (en) * | 2010-12-24 | 2015-09-16 | 日本精工株式会社 | Rolling support device |
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| DE3610528A1 (en) * | 1985-06-14 | 1986-12-18 | Agency of Industrial Science & Technology, Ministry of International Trade & Industry, Tokio/Tokyo | METHOD FOR SUPERPLASTIC MOLDING OF CERAMIC MATERIAL |
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