摘要
The biocompatibility of implantable nickel-titanium biomaterials relies on the quality of their surfaces.In this study,nickel-titanium surfaces are coated with phenolic thin films of tannic acid and pyrogallol with the purpose of studying their corrosion resistance in physiological environments.Three tests are performed:the open-circuit potential test,potentiodynamic polarisation and potentiostatic electrochemical impedance spectroscopy.Polarisation measurements are scrutinised in order to gain knowledge concerning the kinetics of the cathodic and anodic reactions,while the open-circuit potentials and impedance spectroscopy help to study the electrolyte-surficial interactions.It is found that coating nitinol with polyphenols results in the depletion of the native oxide layer and thus a decrease of corrosion resistance.Pyrogallic treated nitinol surfaces(with a corrosion rate of 0.119 mm/year)are half as electrochemically corrosion resistive as tannic acid-coated substrate.Therefore,it is proposed that tannic treated nitinol would be a better option if implanted on biomaterial surfaces.
基金
A.Chatzitakis acknowledges funding from the Research Council of Norway under the NANO2021 program,project number 239211(PH2BioCat).
