Biomimetic apatite deposition behaviors and mechanical performance for as-rolled and
annealed Ni-Ti plates were investigated. Apatite nucleation and growth on Ni-Ti in SBF (simulated
body fluid) was not appreciably influenced by heat treatment. But, the apatite deposition rate
increased slightly by NaOH surface treatment. The nodular apatite on the deposited layer is favored
on a macro-scale since the surface energy of polycrystalline apatite particles can be reduced by
forming nodules. The weight gain after apatite deposition for Ni-Ti (0.004 g/cm2) after 10 days
were found to be smaller that that of NaOH treated Ti-6Al-4V, but it was comparable to that of non-
NaOH-treated Ti-6Al-4V (0.004 g/cm2). The stress-strain responses of annealed Ni-Ti displayed the
pseudoelastic behavior associated with stress-induced martensite formation with the transition stress
for the martensite formation equal to 320 MPa. On the other hand the cold worked Ni-Ti displayed
no appreciable pseudoelastic region and the yield stress was ~500MPa. A good biomimetic apatite
formation and excellent mechanical performance of Ni-Ti suggests that Ni-Ti can be an excellent
candidate material for orthopedic implants.
UV photofunctionalization promotes nano-biomimetic apatite deposition on titanium