Studies On Preparation Of Carbonate-contained Hydroxyapatite/β-tricalcium Phosphate Porous Ceramics And Formation Of The Bone-like Apatite In The Ceramics

In this dissertation, the carbonate-contained hydroxyapatite (HA)/β -tricalcium phosphate (β-TCP) porous ceramics with good pore structure were prepared by adding the porosifer. The relation between the dry-press conditions and the ceramics' quality in forming was discussed in detail. Moreover, the effect of the macropores, the micropores and the phase composition on the formation of bone-like apatite in this ceramics was discussed by using the simulated devices in vitro.Ceramics' quality was closely related to the forming conditions. The results have shown that the carbonate calcium phosphate porous ceramics prepared under the optimum forming conditions had good macropore/micropore structure and other property. The stearic acid ball and PVB powders were selected as maeropore and micropore porosifer, respectively. The optimum forming conditions were concluded that theratio of m calcium phosphate powders: m stearic acid : m PVB Was equal to 1:0.25: 0.3,and 4wt% PVA was added as binder as well as 7MPa was heldfor 3 minutes. And all the materials were mixing by a special method before forming.The porous ceramics were sintered in muffle without Al2O3 powders embedding. Under the optimum sintering schedule of 200℃ for 1h, 800 ℃ for Ih, and 1150℃ for 2h, the porous ceramics exhibited good interconnections between the pores which distributed uniformly. The grain size and the distribution of the calcium phosphate crystals were symmetrical in the ceramics. And the connection between the crystals in the ceramics was the netlike structure, which is good for its osteoinduction.The macropore diameter affected greatly on the formation of bone-like apatite in the ceramics. The results have shown that 300-400 m macropores favored the formation of the bone-like apatite crystals in shorter time when the porous ceramics were immersed in SBF solution. Compared with other porous ceramics with different macropore diameter, this ceramics could form more bone-like apatite crystals when they were immersed in SBF solution for the same time. The crystals were identifiedas the B-substituted bone-like apatite; that is CO32- is substituted for PO4 in the structure of apatite.The micropore porosifer also affected on the formation of the bone-like apatite in the ceramics. The results have shown that the ceramics with PVB porosifer led to better formation of the bone-like apatite compared with the stearic acid porosifer when they were immersed in SBF solution. This is attributed to higher local concentration of Ca and P ion. The ratio of m calcium phosphate powders:rn PVB=1: 0.3 was chose as better condition.The phase composition is also important for the formation of bone-likeapatite in the surface and on the pore wall of the porous ceramics. As for the carbonate-contained HA/β-TCP porous ceramics, when the HA/β -TCP ratio was equal to 9/1, the bone-like apatite crystals could be formed in the surface and on the pore wall in the same immersion time. The results showed that with the increase of β -TCP amount, the formation of bone-like apatite crystals in the surface and on the pore wall of the ceramics was more easy. And when HA/β-TCP ratio was up to 6/4, the bone-like apatite crystals formation was best.