Electrochemical evaluation of AZ31 Mg alloy in corrosion protection of titanium silicon oxide from Earle's solution

Abstract

Magnesium alloys have excellent biocompatibility and good mechanical properties and therefore serve as promising materials for use in orthopedic applications. However, the serious drawback of Mg is its uncontrollable corrosion, which prevents it from being used in potential applications. In this work, a way out has been explored to address this issue. TiSO₄ nanoparticles were deposited on the surface of AZ31 Mg alloy by electrophoretic deposition (EPD) for various time intervals to optimize micro crack coating. The corrosion protection performance of the coated AZ31 Mg alloy was evaluated in Earle's solution. By appropriate characterization techniques, viz., electrochemical impedance spectroscopy (EIS), localized electrochemical impedance spectroscopy (LEIS), scanning electrochemical microscopy (SECM) and potentiodynamic polarization. From the polarization studies the 5 min coating reveals a decrease in corrosion rate, a decrease in i_corr and an increase in resistance. The presence of crystalline TiO₂ and amorphous SiO₂ was confirmed by X-ray diffraction (XRD) studies. Functional group analysis was performed using the ATR-IR technique. Surface morphological studies were examined by scanning electron microscopy (SEM), and XPS analysis was employed to identify the presence of the chemical state of various elements. The bioactivity of the coating was done by immersion studies in Earle's solution. The characterization of the apatite formed was evaluated by SEM with EDX and ATR-IR techniques. An in vitro, cytotoxicity assay was performed with the MG-63 osteoblast-like cell line by MTT assay to calculate the cell proliferation. These results proved that the coating reduced the degradation rate and enhanced the biocompatibility.