Compositions: ceramic – Ceramic compositions – Refractory
Reexamination Certificate
1999-12-21
2002-04-09
Group, Karl (Department: 1755)
Compositions: ceramic
Ceramic compositions
Refractory
C501S001000, C501S087000, C501S097100, C501S095300, C264S125000, C264S641000
Reexamination Certificate
active
06368993
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ceramic composite and a fabrication method thereof, and in particular to a sintered ceramic composite implant material and a fabrication method thereof.
2. Description of the Background Art
Bioceramic implant material is one of the biomaterials that can be replaced for the damaged human tissues. As a substitute material for damaged teeth or bones, apatite has attracted much attention over the past several decades, because of its crystallographical and chemical similarity with various classified tissues of vertebrates. This ceramic is known to be biocompatible, not harmful to tissues, and to form a direct bond with the neighboring bones. Among the apatites that have above-described properties, a hydroxyapatite (hereinafter, referred to as ‘HAp’) is most widely used material.
However, the poor mechanical properties of the HAp compared to those of natural bone are one of the most serious obstacles for load-bearing part replacement. As a result, it is only used for inner ear bone and bone filler as a non-load-bearing part implant. In order to replace the load-bearing hard tissue such as hip joint that has high strength and fracture toughness, HAp needs to be composite with other material. That is to say, it is needed to improve the mechanical properties of HAp.
There has been an approach for the improvement in mechanical properties of the HAp; metal implants coated with HAp, which are widely used these days. The metal part is for mechanical properties and HAp part is for bioactivity and biocompatibility of the implant. However, large differences in physical and thermal properties between the metals and the HAp cast limitation to this approach.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a sintered ceramic composite implant material and a fabrication method thereof which are capable of utilizing the bioactivity and biocompatibility of apatite and of compensating for the poor mechanical properties of apatite.
It is another object of the present invention to provide a sintered ceramic composite implant material and a fabrication method thereof using reinforcement which has similar physical and thermal properties to those of apatite and which are capable of compensating for the poor mechanical properties of apatite without problems caused by differences in physical and thermal properties.
To achieve the above object, there is provided a sintered ceramic composite implant material comprising an apatite matrix phase, and secondary phase composed of ceramic material and located in the apatite matrix phase, and barrier layer coating the secondary phase. The secondary phase improves the mechanical properties of a sintered ceramic composite implant material by compensating for the poor mechanical properties of apatite matrix phase. The barrier layer restrains an interfacial reaction between the apatite matrix phase and the secondary phase.
In another aspect, the present invention contemplates a method for fabricating a sintered ceramic composite implant material, comprising the steps of providing reinforcement powder coated with barrier layer, providing mixed powder by mixing the coated reinforcement powder with apatite powder, sintering the mixed powder. The coated reinforcement powder is provided by making reinforcement powder and barrier layer powder charged with different sign to each other in a suspension.
Additional advantages, objects and features of the invention will become more apparent from the description which follows.
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patent: 5232878 (1993-08-01), Kasuga et al.
patent: 02124775 (1990-05-01), None
patent: WO93/20018 (1993-10-01), None
Kim Hyoun Ee
Kong Young Min
Lee In Seop
Group Karl
Kim Hyoun Ee
Scully Scott Murphy & Presser
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