Formation of TiO2 Nanotube Layer by Anodization of Titanium in Ethylene Glycol-H2O Electrolyte

Alain Robin, Michele Bernardes de Almeida Ribeiro, Jorge Luiz Rosa, Roberto Zenhei Nakazato, Messias Borges Silva

Escola de Engenharia de Lorena, Universidade de S?o Paulo, Lorena, Brazil.
Escola de Engenharia de Lorena, Universidade de S?o Paulo, Lorena, Brazil Faculdade de Engenharia de Guaratinguetá, Universidade Estadual Paulista, Guaratinguetá, Brazil.
Faculdade de Engenharia de Guaratinguetá, Universidade Estadual Paulista, Guaratinguetá, Brazil.

DOI: 10.4236/jsemat.2014.43016                

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 2^k 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.

Keywords

Nanotubes, Titanium, Anodization, Implants

Conflicts of Interest

The authors declare no conflicts of interest.

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