Electrochemical behavior of TiN coatings on stainless steel and titanium nickelide articles for medical purposes

Abstract

Titanium nitride (TiN) coatings which were fabricated by ion-plasma deposition on medical alloys—titanium nickelide (TiNi) and stainless steel were the objects of this study. Their electrochemical and corrosion properties were studied by measuring steady-state potentials in solutions simulating an oral environment by means of a zero-resistance ammeter (ZRA) and the scanning vibrating electrode technique (SVET). The potential difference that arises in the simultaneous presence of structures made of different steel types or steel and titanium nickelide reaches the values higher than the threshold of human sensitivity (about 70 mV). It was found that the protective properties of TiN coatings on the stainless steel surface increase after their annealing at 300–400°С for different times. The titanium nickelide‑titanium nitride galvanic couple was shown to be electrochemically compatible under static conditions. The bending strain of higher than 4.5% was shown to impair the integrity of the titanium nitride layer on the surface of TiNi alloy and induce the potential shift in the negative direction thus deteriorating the corrosion properties of this material.