Matsushita Electric Works, Ltd.

Other

Panasonic Electric Works Co., Ltd.

Panasonic Corporation Works, Ltd.

Masahiro Nawa

Koichi Niihara

Tohru Sekino

Atsushi Nakahira

Tadashi Kokubo

Shoichi Nakamoto

Masaki Uchida

Hideo Nakanishi

Yasuhiko Suehiro

Keiichi Yamasaki

Motoyuki Toki

Keiichi Yamazaki

Kouichi Yamaguchi

A ZrO&#x2014;AlOcomposite ceramic material having excellent wear resistance, hardness, strength and toughness is provided. This ceramic material comprises a ZrOphase composed of 90 vol % or more of tetragonal ZrO, and containing 10 to 12 mol % of CeOas a stabilizer, and an AlOphase. An amount of the AlOphase in the ceramic material is in a range of 20 to 70 vol %, and preferably 40 to 70 vol %. In the composite ceramic material, AlOgrains each having a fine ZrOgrain therein are dispersed. Some of the AlOgrains each having the fine ZrOgrain therein are trapped within ZrOgrains to form composite grains. A ratio of the number of the AlOgrains each having the fine ZrOgrain therein relative to the number of the entire AlOgrains dispersed in the composite ceramic material is 10% or more, and preferably 50% or more.

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A hard tissue repairing material includes zirconia as a base material. A surface of the base material has a hydrophilic group. The hydrophilic group is bonded to zirconium atom in the base material. The base material may contain at least an ionic component that is selected from a group consisting of calcium ion, sodium ion, potassium ion, and phosphate ions within the surface. A hard tissue repairing material may include zirconia as a base material and a layer of a main component of an apatite. The layer of the apatite may be formed on a hydrophilic group bonded to zirconium atom in the base material.

Hard tissue repairing material

A ZrO&#x2014;AlOcomposite ceramic material is provided, which is excellent in mechanical strength and toughness, and has the capability of preventing low temperature degradation. This ceramic material includes a first phase of ZrOgrains having an average grain size of 0.1 to 0.8 &#x3bc;m, and containing 10 to 12 mol % of CeOand 0.005 mol % to less than 0.5 mol % of YO, and a second phase of AlOgrains having an average grain size of 0.1 to 0.5 &#x3bc;m. The ZrOgrains is composed of 90 vol % or more of tetragonal ZrO, and a content of the second phase in the composite ceramic material is in a range of 20 to 60 vol %, and preferably 30 to 50 vol %.

A ZrO&#x2014;AlOcomposite ceramic material having high mechanical strength and toughness as well as excellent wear resistance and hardness is provided. This ceramic material includes a first phase of ZrOgrains containing 10 to 12 mol % of CeOas a stabilizer and having an average grain size of 0.1 &#x3bc;m to 1 &#x3bc;m, and a second phase of AlOgrains having an average grain size of 0.1 to 0.5 &#x3bc;m. The ceramic material has a mutual nano-composite structure formed under a condition that a content of the second phase in the ceramic material is within a range of 20 to 60 vol % such that the AlOgrains are dispersed within said ZrOgrains at a first dispersion ratio of 2% or more, and preferably 4% or more, which is defined as a ratio of the number of the AlOgrains dispersed within the ZrOgrains relative to the number of the entire AlOgrains dispersed in the ceramic material, and the ZrOgrains are dispersed within the AlOgrains at a second dispersion ratio of 1% or more, which is defined as a ratio of the number of the ZrOgrains dispersed within the AlOgrains relative to the number of the entire ZrOgrains dispersed in the ceramic material.

A hard tissue repairing material including a base material and a surface layer having a crystalline zirconia covering the base material, being characterized in that the film includes a Zr&mdash;OH group. A middle layer may be formed between the base material and the surface layer and, in such case, includes at least one element of the base material and at least one element of the surface layer having a crystalline zirconia.

Hard tissue repairing materials and the process for producing the same

A zirconia based ceramic material having improved and well-balanced mechanical strength and toughness consists essentially of 0.5 to 50 vol % of Al.sub.2 O.sub.3 having an average grain size of 2 .mu.m or less and the balance of a partially stabilized zirconia having an average grain size of 5 .mu.m or less. The partially stabilized zirconia consists essentially of 8 to 12 mol % of CeO.sub.2, 0.05 to 4 mol % of TiO.sub.2 and the balance of ZrO.sub.2. Fine Al.sub.2 O.sub.3 grains having an average grain size of 1 .mu.m or less are dispersed within the grains of the partially stabilized zirconia at a dispersion ratio. The dispersion ratio is defined as a ratio of the number of Al.sub.2 O.sub.3 grains dispersed within the grains of the partially stabilized zirconia relative to the number of the entire Al.sub.2 O.sub.3 grains dispersed in the ceramic material, and at least 2% in the present invention. The ceramic material can be made by the following process. A first constituent formed of the partially stabilized zirconia is mixed with a second constituent formed of Al.sub.2 O.sub.3 to obtain a mixture. The mixture is molded into a desired shape, and then sintered in the air under an atmospheric pressure to obtain the ceramic material.

Process of making zirconia based ceramic material

A ZrO.sub.2 based ceramic material having excellent mechanical strength and fracture toughness comprises a first phase of ZrO.sub.2 grains containing CeO.sub.2 as a stabilizer and having an average grain size of 5 .mu.m or less, a second phase of Al.sub.2 O.sub.3 grains having an average grain size of 2 .mu.m or less, and a third phase of elongated crystals of a complex oxide of Al, Ce, and one of Mg and Ca. At least 90 vol % of the first phase is composed of tetragonal ZrO.sub.2. An aluminum (Al) content in the ceramic material is determined such that when Al of the complex oxide is converted to Al.sub.2 O.sub.3, a total amount of Al.sub.2 O.sub.3 in the ceramic material is within a range of 0.5 to 50 vol %. A content of the third phase in the ceramic material is determined within a range of 0.5 to 5 by area %. It is preferred that fine Al.sub.2 O.sub.3 grains having an average grain size of 1 .mu.m or less of the second phase are dispersed within the ZrO.sub.2 grains at a dispersion ratio of at least 2%.

ZrO.sub.2 based ceramic material and method of producing the same

Zirconia based ceramic material

A zirconia based composite material with improved strength and toughness includes a partially stabilized zirconia including 1.5 to 4.5 mol % of yttrium oxide as a matrix thereof and a metal phase of at least one metal selected from the group consisting of titanium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten as metal grains dispersed in the matrix. The metal phase has a melting point higher than a sintering temperature of the partially stabilized zirconia. In addition, it is preferred that the composite material further contains a ceramic phase of at least one ceramic selected from the group consisting of Al.sub.2 O.sub.3, SiC, Si.sub.3 N.sub.4, B.sub.4 C, carbides, nitrides and borides of titanium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten as ceramic grains dispersed in the matrix. The composite material of the present invention is manufactured by the following steps. A mixture is prepared by incorporating at least one first constituent forming the partially stabilized zirconia with at least one second constituent forming the metal phase, and if necessary, at least one third constituent forming the ceramic phase. The mixture is sintered in a non-oxidation atmosphere to obtain the composite material.

Zirconia based composite material and method of manufacturing the same

A sintered ceramic-metal composite product has a ceramic matrix of polycrystalline ceramic in which a metal phase is dispersed for adding improved toughness. The metal phase has a higher melting point than the sintering temperature of the ceramic matrix and comprises at least one metal selected from the groups IVa, Va and VIa of the periodic table. The metal phase is dispersed intragranular within the grains of the ceramic matrix to realize nano-order dispersion of the metal phase which is responsible for remarkably improved toughness as well as strength. The ceramic-metal composite product is successfully fabricated by several unique methods utilizing the mixture of the ceramic and metal or metal oxide, hydride or alkoxide.

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Katano, Japan

Masahiro Nawa