Fiber reinforced ceramics of calcium phosphate series compounds

Details Fiber reinforced ceramics of calcium phosphate series compounds Fiber reinforced ceramics of calcium phosphate series compounds

1989-09-27

1992-02-25

Dixon, Jr., William R.

Compositions: ceramic

Ceramic compositions

501 95, 501 32, 501123, 106 35, 264 60, 264 62, 423308, 423311, C04B 3500

Patent

active

050913441

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to fiber reinforced ceramics of calcium phosphate series compounds, and proposes fiber reinforced ceramics of calcium phosphate series compounds in which flawless heat-resistant inorganic short fibers are three-dimensionally and uniformly dispersed in a matrix composed of calcium phosphate series compound and entangled with each other to form a high strength shaped body and hence provide both high strength and high rupture toughness values as well as a method of producing the same.


BACKGROUND ART

Recently, ceramics of calcium phosphate series compounds such as apatite hydroxide [Ca.sub.10 (PO.sub.4).sub.6 (OH).sub.2 ], tricalcium phosphate [Ca.sub.3 (PO.sub.4).sub.2 ] and the like are expected as an implant material for artificial tooth root, artificial bone or the like because of excellent bioaffinity. However, these calcium phosphate compound ceramics cannot be said to have sufficient strength and toughness against mechanical impact or stress produced when being used as the artificial bone or tooth root, so that they are not yet put into practical use at present.
Under obtaining above circumstances, there has hitherto been made many studies and developments for the implant materials having excellent affinity to biotexture as well as excellent strength and toughness. Among them, composite ceramics obtained by adding heat-resistant inorganic short fibers to the calcium phosphate series compound ceramic are highlighted as effective.
For instance, there are proposed "Artificial tooth, artificial bone and method of producing the same" in Japanese Patent Application Publication No. 59-219, "Carbon fiber-apatite series composite fired bodies" in Japanese Patent Application Publication No. 61-41876, "Mineral fiber-apatite series composite fired bodies" in Japanese Patent laid open No. 59-57971 and the like as a related technique, and also there is a study by Iida, Iijima et al, "Fiber reinforced apatite through pressurized sintering so as to orient mild carbon fibers into long axis direction" in Association of Japan Ceramics, abstract collection for forum, forum item number 3G09.
In the case of the above conventional techniques, the toughness of apatite is somewhat improved, but there are not yet developed high density fiber reinforced apatities satisfying conditions required as an implant material for artificial bone, artificial tooth root or the like, i.e. having excellent strength and toughness.
That is, the high density fiber reinforced apatites produced by these known techniques have a drawback that a large shrinkage is caused during the sintering because a relatively low density green shaped body is forcedly densified by sintering under a pressure. In other words, the heat-resistant inorganic fibers such as whisker and the like contained in the green shaped body are subjected to a large deformation during the pressurized sintering or broken in extreme cases. Furthermore, the mixture of powder and fibers is merely fixed, so that the adhesion property between the fiber and the powder matrix is poor. Therefore, the toughness and also the strength are not so improved through the heat-resistant inorganic fibers are added.
Furthermore, in the above conventional techniques, the heat-resistant inorganic fibers are apt to be oriented in a two-dimensional direction, so that the anistropy is caused in the strength and toughness, and consequently there should be considered the anisotropy in use.
It is an object of the invention to propose fiber reinforced ceramics of calcium phosphate compounds capable of advantageously solving the above drawbacks of the conventional technique as well as a method of producing the same.


DISCLOSURE OF INVENTION

Now, the inventors have made various studies with respect to fiber reinforced calcium phosphate series compound ceramics capable of solving the aforementioned drawbacks of the conventional technique and having excellent strength and toughness, as well as their production method. Consequently, they have developed novel ceramics and the

REFERENCES:
patent: 4215033 (1980-07-01), Bowen
patent: 4230455 (1980-10-01), Hidaka et al.
patent: 4503157 (1985-03-01), Hatahira

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