engleski

Corrosion behaviour of Nitinol in the simulated physiological solution

In this work the corrosion properties of Nitinol (NiTi alloy) was studied using different electrochemical techniques such as open circuit potential measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The concentration of dissolved nickel from alloy in 0.9% NaCl solution after EIS measurements was measured with a high- performance atomic absorption spectrometer. Sample made from NiTi alloy with diameter of 4 mm was used. Corrosion properties were tested in 0.9 % NaCl solution at pH=7.4 and temperature 37 °C (simulated body fluid). The NiTi alloy is characterized by a relatively small passive region which indicates the susceptibility for localized corrosion, but the corrosion rate is very low. The oxide film formed on NiTi alloy surface has a double-layer structure consisting of a barrier-type inner layer and a porous outer layer. Also, dissolved nickel ions concentration after 24 hours of the NiTi immersion in 0.9 % NaCl solution is smaller than the daily dietary intake level.

NiTi alloy ; corrosion rate ; potentiodynamic polarization ; EIS ; dissolved nickel

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