In vitro corrosion behavior of coated Ti6Al4V with TiO2, ZrO2, and TiO2/ZrO2 mixed nanofilms using atomic layer deposition for dental implants

Ti-6Al-4 V (Ti(V)) is a biocompatible material with good mechanical properties, widely used as an implant in dental and orthopedic applications. However, it is susceptible to corrosion when it is in contact with the human body and mouth environment. To overcome this drawback and enhance its use in dental applications, we functionalized this alloy using Atomic Layer Deposition (ALD). Thin films of TiO2 and ZrO2 were deposited on polished Ti(V) discs by ALD as single and mixed oxides. Four groups were characterized: non-deposited Ti(V) (control); TiO2 deposited; ZrO2 deposited; mixed TiO2/ZrO2 film with 1:4 thickness ratio (TZO). ALD precursors and oxidizer were tetrakis(dimethylamido)titanium, tetrakis(dimethylamido)zirconium, and ozone, respectively. The existence and composition of each coating were confirmed with x-ray photoelectron spectroscopy. Electrochemical tests were performed in artificial saliva solution at 37 ± 1 °C to investigate the corrosion behavior of the surface in simulated oral conditions. The corrosion rate was decreased by over 64 % on the coated samples compared to the control. The surface roughness and morphology of the areas were analyzed before and after corrosion using optical profilometry, scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDS), respectively. The surface roughness and topography of the samples did not change significantly after the corrosion. However, the SEM and EDS results revealed that the TZO group had the best surface protection against corrosion compared to the control and either of single oxides. The results of this study indicated that having a combination of TiO2 and ZrO2 in the form of an ultra-thin film with a thickness of ~30 nm would provide protection of Ti(V) surfaces in artificial saliva, thereby enhancing the dental implant robustness and lifetime in the aggressive oral environment, and therefore increasing patient satisfaction.