Zr and Ti
alloys are extensively used in the biomedical field owing to their optimal mechanical properties and excellent corrosion resistance. Fully ceramic implants based on
zirconia are appealing with respect to the traditional Ti-based metallic ones for several reasons, such as: (i) improved aesthetic impact, (ii) better biocompatibility and (iii) better osteointegration. Nevertheless, fully ceramic implants exhibit serious mechanical and clinical drawbacks, chiefly brittleness and impossibility of post-implant position adjustments. In this paper we propose the novel approach of using a
metal-based system, consisting of metallic Zr, for the bulk of the implant and an electrochemically grown
zirconia coating, ensuring contact of the ceramic with the
biological environment and isolation from the underlying
metal. This
solution combines the outstanding mechanical properties of the
metal in the bulk with the optimal biochemical properties exclusively where they are needed: at the surface. The present paper-focussed on the electrochemical behaviour of the proposed system at the implant-
wound and implant-growing bone interface-reports a time-dependent electrochemical corrosion study of
zirconia-coated
zirconium, performed in the following ways: (i) exposure and measurements in SBF (simulating the inorganic part of human plasma, relevant to
wound chemistry), (ii) exposure and measurements in SBF with added
glycine (the simplest, ubiquitous
amino acid found in
proteins), (iii) exposure in SBF with added
glycine and measurements in SBF. Electrochemical impedance spectra were measured and interpreted with the equivalent-circuit approach, yielding estimates of the time-variation of the
oxide film thickness and resistance were estimated. FT-IR, Surface Raman and VIS reflectance spectroscopies were used to characterise the surface before and after the exposure to SBF solutions. Spectroelectrochemical measurements revealed an higher corrosion resistance of the
oxide films formed on Zr in the presence of
glycine in the SBF matrix and a smoother
electrode surface.