Formation of bioactive functionally graded structure on Ti-6Al-4V alloy by chemical surface treatment.
An Al- and V-free sodium titanate hydrogel layer with a graded structure where the sodium titanate gradually decreases toward the interior, was formed on the surface of Ti-6Al-4V alloy, when the alloy was exposed to 5M NaOH solution at 60 degrees C for 24 h. This gel layer was transformed into an amorphous sodium titanate layer without giving considerable change in the graded structure, except a little increase in the depth of the oxygen distribution by a heat treatment at 600 degrees C for 1 h. The sodium titanate layer formed Ti-OH groups on its surface by exchanging its Na+ ion with H3O+ ion in simulated body fluid when soaked in the fluid, and thus formed Ti-OH groups induced the apatite nucleation. The apatite layer also formed a graded structure toward the substrate. The strong bond of the apatite layer to the substrate was attributed to this graded structure.
Kim
H M
HM
Department of Material Chemistry, Faculty of Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. kim@sung7.kuic.kyoto-u.ac.jp
Takadama
H
H
Miyaji
F
F
Kokubo
T
T
Nishiguchi
S
S
Nakamura
T
T