| The research of biocomposites combining the bioactivity of nano-hydroxy-apatite (nHA) and excellent mechanical properties of titanium (Ti) is the hotpot of biomedical and material science and engineering. There are academical and scientific significances and bright prospects for the researching of HA/Ti biocomposites. This work focused on processing of the nHA/Ti composite powders and nHA/Ti biocomposite by using mechanical ball milling and powder metallurgy respectively. The effects of sintering processing and original component on the microstructure, density, hardness, compressive elastic modulus and flexural strength were studied. The decomposition of pure nHA and the interface reaction of nHA/Ti composites in vacuum sintering were discussed respectively. Then the in vitro bioactivity of the selected composites was performed systematically in simulated body fluid (SBF).The nHA/Ti composite powders are refined with increasing of milling time. The refined structure and homogeneity are acquired via milling for 30h.It has been found that the decomposition components of nHA are made of β-Ca3(PO4)2 and Ca4P2O9 after sintering at 1200℃. The phases of Ti2O,Ti5P3, CaTiO3 and TiOx are found in nHA/Ti composites after sintering at 1100℃.The effects of flexural strength and compressive elastic modulus for nHA/Ti composites are accounted for the changes of original component and sintering temperature. The results show that the flexural strength of the same component of nHA/Ti composites sintered at 1100℃ is higher than 900℃,1000℃ and 1200℃ . The 90%Ti-nHA composite sintered at 1100℃ has the highest flexural strength (165MPa), which is higher than the cortical bone (160MPa). The compressive elastic modulus(10. 426GPa) is similar to the nature bone (4.9GPa—9.5GPa) .The in vitro test results show that the 90%Ti-nHA composite exhibits excellent bioactivity.The deposition procedure is closely related to the Ti-OH groups, Ca,P components and micro-porous structure. The hydrothermal pre-oxidation treatment improves the bioactivity of composites apparently.It can conclude that the 90%Ti-nHA composite sintered at 1100℃ is hopefully used in prosthodontics and oral implantology due to its excellent biomechanical compatibility and bioactivity. |
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