TITLE:
Formation of TiO2 Nanotube Layer by Anodization of Titanium in Ethylene Glycol-H2O Electrolyte
AUTHORS:
Alain Robin, Michele Bernardes de Almeida Ribeiro, Jorge Luiz Rosa, Roberto Zenhei Nakazato, Messias Borges Silva
KEYWORDS:
Nanotubes, Titanium, Anodization, Implants
JOURNAL NAME:
Journal of Surface Engineered Materials and Advanced Technology,
Vol.4 No.3,
April
28,
2014
ABSTRACT: In orthopaedics and
orthodontics, the growth of nanotubes of titanium oxide on titanium implants is
a promising route for improving the osseointegration. Among the fabrication
routes to produce nanotubes, anodization was generally preferred due to its
simplicity and low cost. TiO2 nanotubes are formed by the simultaneous
anodic reaction and chemical dissolution due to the fluoride species present
in the anodization bath. In this work, the formation of TiO2 nanotubes was studied in stirred ethylene glycol-H2O electrolyte (90
- 10 v/v) containing NH4F at room temperature. In order to study
the effect of NH4F concentration, voltage and anodization time, and
to reduce the number of experiments, a design of experiments (DOE) based on a 2k factorial design with four replicates at the center point was used. The analysis
of variance (ANOVA) was used to evaluate the effects of the factors of control
and their interactions on the percentage of the titanium surface coated by
nanotubes. The dimensions of nanotubes (length and diameter) were also
evaluated using field emission gun scanning electron microscopy. The
cristallinity and phase composition of the oxide layers was investigated by
X-ray diffractometry. The electrochemical behavior of as-received and
anodized titanium specimens was studied in Ringer’s solution. The statistical
analysis showed that fluoride concentration is the most significant factor. The
best condition according to the response surface analysis is the center point
(1% NH4F, 20 V, 2 h). The nanotubular oxide layers presented an
amorphous structure. Electrochemical tests showed that TiO2 nanotubes coated titanium is less corrosion resistant than as-received
titanium.