Improved in vitro bioactivity and electrochemical behavior of hydroxyapatite-coated NiTi shape memory alloy

Abstract

Nickel titanium (NiTi) shape memory alloys have a vigorous prospective for biomedical solicitations. In this work, electrochemical behavior of hydroxyapatite (HA) coated and thermally oxidized near equiatomic NiTi shape memory alloys was efficaciously investigated for biomedical applications. NiTi samples were spin-coated with laboratory-synthesized HA followed by drying and calcination at 120 +/- 5 degrees C and 450 +/- 5 degrees C, respectively. Similarly, uncoated NiTi samples were thermally oxidized by heating at 450 +/- 5 degrees C in air. The comparison was made among HA-coated, thermally oxidized and uncoated samples. Scanning electron microscope (SEM), atomic force microscope and X-ray diffraction confirm the presence of Titania and HA coating on the NiTi substrates. Electrochemical testing results showed the better resistance against corrosion for the HA-coated samples because of the protective coatings of HA and Titania, as compared to the rest. Moreover, Fourier transform infrared spectroscopy and SEM reveal that the HA-coated sample will provide bioactive cushion to the host structure for better adhesion during the implanted period, while the implant will do its job.