Structure and Corrosion Behavior of TiO 2 Thin Films Deposited by ALD on a Biomedical Magnesium Alloy.

Magnesium alloys have been investigated as temporary biomaterials for orthopedic applications. Despite their high osseointegration and mechanical (bone-like) properties, Mg alloys quickly degrade in simulated physiological media. Surface coatings can be deposited onto Mg alloys to slow the corrosion rate of these biomaterials in chloride-rich environments. TiO₂ films show high potential for improving the corrosion resistance of magnesium alloys. This article presents the structural observations and corrosion behavior of TiO₂ thin films deposited onto a MgCa2Zn1Gd3 alloy using atomic layer deposition (ALD). Surface morphologies were observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and Raman analysis of the deposited TiO₂ films was also carried out. The corrosion behavior of the uncoated alloy and the alloy coated with TiO₂ was measured in Ringer's solution at 37 °C using electrochemical and immersion tests. The microscopic observations of the TiO₂ thin films with a thickness of about 52.5 and 70 nm showed that the surface morphology was homogeneous without visible defects on the TiO₂ surface. The electrochemical and immersion test results showed that the thin films decreased the corrosion rate of the studied Mg-based alloy, and the corrosion resistance was higher in the thicker TiO₂ film. [ABSTRACT FROM AUTHOR]