Preparation Of Titanium Composites By Powder Metallurgy And Its Bioactivity And Tribology Research

The biocomposites of titanium and nano-hydroxyapatite (nHA) have been developed for thehard tissue implant for their superior biocompatibility and mechanical properties. Thecomposites are thought to be the prospective substitute of hard tissue, so they have recentlybecome a hot topic in the field of biomaterials. The nHA/Ti biocomposites have both thescientific signification and the promising applications in clinic. In this paper the biocompositeswere prepared by using powder metallurgy. Mechanical properties, the interface reaction,microstructure, bioactivity and bio-tribology properties of the composites were studied.The results indicated that the original component and sintering temperature are the principalfactors to determine compressive elastic modulus and flexural strength of nHA/Ti composites.The compressive elastic modulus(9.345GPa) of the 90%Ti—nHA composite sintered at 1100℃is similar to the cortical bone(4.9GPa～9.5GPa), so its biomechanical compatibility is preferable.The flexural strength of the nHA/Ti composites sintered at 1100℃is higher than that at 1050℃and 1150℃. The flexural strength (154.4MPa) of the 90%Ti—nHA composites sintered at 1100℃is equivalent with the hominine bone.It has been unfound that the new phase of nHA and Ti after sintered respectively at 1100℃.The phases of Ti₂O, Ti₅P_3.16 and CaTiO₃ are found in nHA/Ti composites after sintered at1100℃.The in vitro test in the simulated body fluid (SBF) results showed that the 90%Ti—nHAcomposite exhibits excellent bioactivity. It is proved that the Ti—OH groups, Ca,P componentsand micro-porous structure of composite have advantageous to promote the apatite formation.The hydrothermal treatment improves the bioactivity of composites apparently.The osteoblast culture test showed that the 90%Ti—nHA composite sintered at 1100℃hasno toxic effect on osteoblast. Osteoblast can adhere to material surface and grow into theporosity of material and proliferate. The 90%Ti—nHA composite has good bioactivity. Thedeposit apatite layer exhibited porous netty structure which is similar to the alveolate frabric ofhominine cortical bone.The principal type of sliding friction and wear of nHA/Ti composites in condition of SBFlubricating is abrasive wear. The wear volume and the friction coefficient (0.04444) of 90%Ti—nHA composite sintered at 1100℃against UHMWPE are smaller than other test materials. The90%Ti-nHA composite sintered at 1100℃has better friction and wear resistance.It can conclude that the 90%Ti—nHA composite sintered at 1100℃is hopefully used insubstitute of hard tissue due to its excellent biomechanical compatibility, bioactivity andbio-tribology properties.