Surface Engineering of Titanium via a Two-Step Electrochemical Anodization Process: Mechanism of Nucleation and Growth of Titanium Oxide Nanotubes

Document Type : Original Articles

Authors

Faezeh Darvishian Haghighi

Nazanin Yazdan Parast

Sahar Mollazadeh Beidokhti

Mohsen Haddad Sabzevar

Department of Materials Science and Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

10.22067/jmme.2026.95575.1224

Abstract

In recent years, titanium oxide nanotubes (TiO₂ NTs) grown on titanium metallic substrates have attracted significant attention due to their wide applications in biomedical and energy-related fields. Electrochemical anodization is considered one of the most effective methods for producing these nanotubular structures. The present study aims to investigate the influence of a two-step electrochemical anodization process on the physicochemical properties of titanium oxide nanotubes. Following anodization, the fabricated coatings were characterized using various metallurgical techniques. Raman spectroscopy confirmed the presence of characteristic peaks of titanium oxide in the developed layer. Phase analysis using X-ray diffraction (XRD) revealed that the formed nanotubes consisted of TiO₂ nanocrystallites with anatase as the dominant phase. Moreover, field-emission scanning electron microscopy (FESEM) observations demonstrated that two-step anodization remarkably improves the nanotube structural order compared to single-step anodization, as the nanotubes grow during the second stage based on a pre-formed template, resulting in highly parallel and well-aligned structures. Contact angle measurements indicated a 38.78% reduction in wettability angle, signifying enhanced surface hydrophilicity after two-step anodization. Additionally, atomic force microscopy (AFM) analyses revealed an increase in surface roughness from 69.8 to 285.3 nm, which improves the specific surface area. Such enhancement in surface roughness is considered beneficial for biomedical applications, particularly in implant technology. Therefore, it can be concluded that two-step anodization is a key process for engineering and optimizing titanium-based nanotubular structures.

Keywords

Titanium Oxide Nanotubes

Electrochemical Anodization Process

Nucleation Mechanism

Subjects

• Advanced Materials

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