| The work of this thesis primary has three parts : 1) Preparation and characterization of nano-sized hydroxyapatite/β-tricalcium phosphate compound powder and bio-ceramic; 2) Preparation and Properties of Porous Bioceramics Made of Bovine Bone; 3) Sintering Kinetics of Hydroxyapatite Ceramics.Nano-sized hydroxyapatite/β-tricalcium phosphate (HAP/β-TCP) compound powder was prepared by the glycine-nitrate process.The best mechanical Properties can be obtained when the HAP bioceramics were sinteringed at 1300oC for 3 hours,which was consistent with the demand of human bone.Hydroxyapatite can be produced from bovine-bone by heat treatment. It was found that the HAP was decomposed and TCP created when the sintering temperatures was higher than 1200oC. The bending strength was similar to those from artificial HAP ceramic, and the Young's modulus was smaller, which was more close to those of nature bone.The porous hydroxyapatite (HAP) bioceramics was prepared using HAP powder from calcined bovine bone and urea as pore-creating agent. The average pore size was about 110μm. The porosities distribute from 34%～60%. As a kind of special materials, porous ceramics which had internected microstructure can produce high ductility and shock resistance while was inplanted in the human body.The sintering kinetics of the hydroxyapatite ceramics which was produced from synthesis and bovine-bone was investigated by stepwise isothermal dilatometry (SID), combined with XRD and SEM. The isothermal shrinkage data of synthesis HAP from SID can be well analyzed to get kinetic parameters according to the empirical rate equation developed by Makipirtti-Meng and the value of apparent activation energy obtained at 1000℃～1150℃was 86.3kJ/mol. Similarly, the exponent n that can be served to reveal the morphology changing during the sintering process are also much different in the two temperature ranges, which is well consistent with the SEM observation. |
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