BIOMIMETIC DEPOSITION OF APATITE ON SURFACE CHEMICALLY MODIFIED POROUS <font>NiTi</font> SHAPEMEMORY ALLOY

Porous NiTi shape memory alloy (SMA) with 48% porosity and an average pore size of 50–800 μm was synthesized by capsule-free hot isostatic pressing (CF-HIP). To enhance the surface bioactivity, the porous NiTi SMA was subjected to H 2 O 2 and subsequent NaOH treatment. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses revealed that a porous sodium titanate ( Na 2 TiO 3 ) film had formed on the surface of the porous NiTi SMA. An apatite layer was deposited on this film after immersion in simulated body fluid at 37°C, while no apatite could be found on the surface of the untreated porous NiTi SMA. The formation of the apatite layer infers that the bioactivity of the porous NiTi SMA may be enhanced by surface chemical treatment, which is favorable for its application as bone implants.