Electrochemical Investigation of Nitinol/Tantalum Hybrid Surfaces Modified with Phosphonic Acid Derivatives

Nitinol, a nickel and titanium alloy in quasi-equiatomic proportions, is used in numerous biomedical applications due to its remarkable mechanical characteristics, its resistance towards corrosion and good biocompatibility. Further research to reinforce osseointegrative abilities and barrier properties towards external aggressive agents are still needed.

In this context, electrochemical methods can be used to generate protective and functional surface coatings on Nitinol substrates with a good level of control and versatility. Specifically here are considered the elaboration of a structured thin layer on Nitinol plates by electrodeposition of tantalum and its subsequent modification by the self-assembly of phosphonic acid derivatives to consolidate corrosion protection and bioactivity features.

 Electrochemical techniques are also used to assess and study the different deposited layers. Cyclic voltammetry, polarization curves, free potential measurements, and scanning electrochemical microscopy experiments are performed to qualitatively and quantitatively evaluate electron and mass transfers at the interface, as well as corrosion resistance properties. Spectroscopic (XPS) and microscopic (SEM) analyses complete the characterization process regarding chemical nature and morphology aspects.