Nanotube shape changes on Ti-6Al-4 V alloy via various applied potential for bio-implants.

Surface modification of dental implants or orthopedic implants is important for biocompatibility, and Ti-6Al-4 V alloy is mainly used as implant material for clinical use. In particular, research on the formation of nanotubes for drug doping to improve biocompatibility is in progress. For the control of nanotube shape, in this study, nanotube shape changes on Ti-6Al-4 V alloy via various applied potential for bio-implants were researched using various instruments. The formation of nanotubes on the surface of the Ti-6Al-4 V alloy was performed using a DC power source as a two-electrode system, and platinum as a counter electrode and a working electrode as an anode. The electrolyte was 0.8 wt. % NaF solution and 1.0 M H₃PO₄ were used and mixed using a magnetic bar during anodization. At this time, the voltage applied when forming the nanotubes was varied as (10 → 20 → 30 V), (30 → 10 → 30 V), and (10 → 30 → 30 V), respectively, and these voltages were applied for 30 min for each step. After the formation of nanotubes, the surface morphology and structural properties of the samples were observed using field-emission scanning electron microscope, X-ray diffractometer, Fourier transform infrared spectroscopy, and nanoindentation tester. The higher the voltage applied during the formation of nanotubes, the larger is the diameter. In the case of the nanotube (10 → 20 → 30 V), the top of the nanotube was narrow and the diameter increased toward the bottom, forming a cone shape. In the case of the nanotube (30 → 10 → 30 V), a narrow waist shape was formed, and in the case of the nanotube (10 → 30 → 30 V), a jar shape was formed with anatase and rutile phases. From the FT-IR results, when nanotubes are formed, TiO₂ anatase was detected and showed the tendency to change from crystallization to amorphous state. The indentation hardness and elastic modulus decreased for the nanotube surface compared with those of the bulk Ti alloy. [ABSTRACT FROM AUTHOR]