Thermal degradation of TiO2 nanotubes on titanium

Abstract

The objective of this research was to study thermal degradation behavior of TiO2 nanotubes on titanium (Ti). TiO2 nanotubes were grown via anodization method on commercially pure Ti (Cp-Ti) discs using two different electrolytes, 1vol. % HF in deionized (DI) water and 1vol. % HF+0.5wt. % NH4F+10vol. % DI water in ethylene glycol, to obtain nanotubes with two different lengths, 300nm and 950nm keeping the nanotube diameter constant at 100±20nm. As grown TiO2 nanotubes were subjected to heat treatment to understand thermal degradation as a function of both temperature and hold time. The signs of degradation were observed mainly when amorphous nanotubes started to crystallize, however the crystallization temperature varied based on TiO2 nanotubes length and anodizing condition. Overall, 300nm nanotubes were thermally stable at least up to 400°C for 12h, while the 950nm long nanotubes show signs of degradation from 400°C for 6h only. Clearly, length of nanotubes, heat treatment temperature as well as hold times show influence toward degradation kinetics of TiO2 nanotubes on titanium.