In-vitro electrochemical study of TiB/TiB2 composite coating on titanium in Ringer's solution

Highlights: • Boriding of Cp-Ti at 900 and 1000 °C for 3 h forms TiB and TiB/TiB₂, respectively. • The better electrochemical performance was observed for borided samples. • TiB coating has better in-vitro electrochemical behavior than TiB/TiB₂. • Borided sample at 900 °C represents the highest polarization resistance. • Passive films formed on all samples behave as n-type semiconductor. In this work, different electrochemical analyses in Ringer's solution at 37 °C were implemented to understand the electrochemical response of diversity of titanium boride coatings developed on the commercially pure titanium (CP–Ti) via pack cementation method. X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images indicated that the boriding creates the TiB whiskers and TiB whiskers/TiB₂ dense layer on the top of the surface of CP–Ti in respect to the heat-treatment at 900 and 1000 °C for 3 h. Potentiodynamic polarization curves cleared the passive behavior of the borided samples. Electrochemical impedance spectroscopy (EIS) assays revealed the satisfactory corrosion resistance of the borided samples in Ringer's solution. Mott–Schottky (M–S) assessments represented that the passive films formed on CP–Ti and the borided samples behaved as doped n-type semiconductor properties. Furthermore, M–S assessments indicated that the donor concentration of the passive films decreased with increasing the time. Finally, the borided sample at 900 °C in comparison with the borided sample at 1000 °C illustrated to be the more suitable selection for bioimplant applications, mainly due to better surface conditions to form a less defective and more protective passive film.