| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2001: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2000: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
The objective of this study is to establish methodology fundamentals for preparation of titanium and titanium alloys with high bioactivity and fracture resistance, upon clarifying compositional and structural dependences of bioactivity of titania gels by investigating apatiteforming abilities of titania gels with different compositions and structures.
Titania gels with different compositions and structures were prepared by sol-gel process and subsequent heat treatments in TiO_2, Na_2O-TiO_2, CaO-TiO_2 systems to be immersed in simulated body fluid (SBF) with ion concentrations nearly equal to those in blood plasma. The gels were found to form apatite on its surface in SBF, when they contained anatase or rutiles. The apatiteforming ability of the gel was known to increase with the amount of anatase in the gel, implying that titania with anatase structure is most effective for apatite formation in body environment.
Upon basis of this finding, titanium metal was subjected to NaOH, hot-water, and subsequent heat treatments at various conditions to be formed with anatase structure with high bioactivity on its surface. The NaOH and hot-water treatments was found to give, respectively, formation of thin hydrogel layer of sodium titanate on the metal, and transformation of the sodium titanate gel into titania gel with amorphous or anatase structure by release of sodium ion. Heat treatment at 600 ℃ made the titania transform into anatase with increasing its amount. The titanium metal subjected to the NaOH, hot-water and subsequent heat treatment was immersed in SBF to form apatite on its surface in an early stage of soaking. This indicates that the titanium metal, which was formed with anatase on its surface by the NaOH, hot-water and subsequent heat treatment, would reveal high bioactivity as well as high fracture resistance, and therefore be useful as artificial bone materials even under load-bearing conditions.
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