Comparative Study of Anodized Titanium Surfaces: The Effect of Low Voltage on the Morphology, Performance, and Corrosion Resistance of the Double Layer

The anodizing process of titanium (Ti) implants and their alloys improves their corrosion resistance and life service by naturally increasing the thickness of the passive oxide layer formed on the surface. Among the parameters that affect the properties of the anodized layer, voltage is a significant one due to the kinetic and thermodynamic processes. In this paper, commercial pure titanium (cp-Ti) coupons with the dimensions of 20 ×10 × 1 mm3 were used as the anode in 1 M sulfuric acid solution at different voltages of 3, 6, and 9 V, current intensity of 3 A, electrolyte temperature of 60 °C, and duration time of 30 s. The phase composition analysis, morphology, and corrosion behavior of the anodized Ti were examined by Grazing‐Incidence X‐Ray Diffraction (GIXRD), Field‐Emission Scanning Electron Microscopy (FESEM), and electrochemical impedance, respectively, in Simulated Body Fluid (SBF) at 37 °C. The results confirmed the formation of titanium oxide coating with a hexagonal structure. A smoother surface was obtained upon increasing the voltage up to 6 V. However, the surface became rougher with further voltage increase up to 9 V. The highest charge transfer resistance (37354 and 58127 ohm.cm-2) was achieved at 6 V after 1 and 24 hours of immersion in the SBF solution, representing 84 % and 2440 % increase, respectively, compared to the cp-Ti sample. The double layer helps prevent the formation of localized corrosion sites, such as pitting and crevice corrosion, which can be particularly damaging to Ti alloy as an implant in the human body. Although rising the voltage from 3 to 6 V resulted in a more hydrophobic surface (as shown by an increase in the contact angle from 63.8° to 74.1°), further voltage increase up to 9 V made the surface more hydrophilic than before.