Tuning the Mechanical and Antibacterial Properties of ZrO2 Thin Films by Varying Deposition Angle and Orientation for Biomedical Applications

This paper investigates the properties of zirconium oxide thin films deposited on Ti6Al4V and Si substrates via oblique angle deposition, using varying out-of-plane θ (15 to 85°) and in-plane Φ (0 and 180°) substrate orientations. ZrO2 films have garnered significant interest due to their antibacterial properties and mechanical performance. The aim is to engineer surfaces capable of inhibiting bacterial growth while maintaining excellent mechanical integrity. The methodology combines experimental deposition by DC magnetron sputtering with multi-scale simulations using SRIM and SIMTRA. Structural analyses were conducted via X-ray diffraction, while microstructure and surface morphology were examined using scanning electron microscopy and atomic force microscopy. Nanoindentation tests were performed to assess hardness and elastic modulus. Results revealed that increasing the incidence angle α from 7 to 74° significantly affected surface morphology, microstructure, film thickness, and columnar tilt. The hardness and Young’s modulus of the films exceeded those of Ti6Al4V, for incidence angle α between 7 and 50°, but decreased with the increasing incidence angle α. Furthermore, the films exhibited strong antibacterial activity against Gram-positive pathogens (Staphylococcus aureus), particularly at the highest incidence angle α, with inhibition rates exceeding 90%.