A comparison of electrochemical behavior of coated nanostructured Ta on Ti substrate with pure uncoated Ta in Ringer's physiological solution

Highlights: • NS-Ta coating was coated on Ti through direct current magnetron sputtering. • NS-Ta coating demonstrated a higher film growth rate compared to pure Ta. • NS-Ta coating showed a higher corrosion resistance in comparison with pure Ta. • Passive film of NS-Ta is much more resistant and thicker than that formed on pure Ta. • After 24 h, passive films of NS-Ta and Ta have become more resistant, thicker and even less defective. In the current investigation, direct current magnetron sputtering (DCMS) provided nanostructured (NS) α-Ta coating on pure Ti substrate as an effective coating technique. Microstructural observations revealed that a dense and homogeneous coating exhibiting (110) preferred orientation could be achieved. Different electrochemical experiments were performed to study the electrochemical and passive behaviors of α-Ta coating and uncoated commercially pure Ta in the Ringer's physiological electrolyte at 37 °C. Interestingly, the electrochemical response and semiconducting behavior of α-Ta coating and pure Ta were different in several aspects. α-Ta coating showed a superior passive behavior and higher level of protection in Ringer's physiological electrolyte at 37 °C compared to pure Ta. Mott–Schottky (M–S) analysis clearly showed that a less defective passive film forms on α-Ta coating due to its lower levels of donor densities compared to what could be estimated for the case of pure Ta. α-Ta coating offered a considerably improved corrosion resistance in the aforementioned physiological environment, owing to its nano-scale features that have facilitated the formation of less defective and thicker protective passive films.