Abstract
Magnetron sputtering method is used to coat a bi-phase Ta/TaxOy multilayer on NiTi shape memory alloy as a self-expandable stent. These coatings are created to improve the properties of the surface, such as radiopacity, in-vitro corrosion resistance, and biocompatibility. Thin films are formed by simultaneously sputtering the tantalum target in an ArO2 environment, to prevent target poisoning, the ratio of the volume percentage of oxygen to the total inlet gas is 16.6 (Vol%). In addition, the effect of substrate temperature has been studied in this gas composition.Atomic force microscopy has been used to analyze surface topography and roughness. Via potentiodynamic scanning and electrochemical impedance spectroscopy, the electrochemical behavior of the uncoated and coated samples is determined in SBF solution at 37 ± 0.5 °C. Also, the amount of Ni ions released has been analyzed using inductively coupled plasma-optical emission spectrometry. As a result, the Ta/TaxOy thin films deposited at 200 °C represent excellent corrosion resistance. These practical consequences provide a possible procedure to recover the efficiency of Ta/TaxOy coatings on NiTi alloys.
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