Magnetron sputtered ß-Ti coatings for biomedical application: A HiPIMS approach to improve corrosion resistance and mechanical behavior

• TNZT coating decreased Young’s Modulus more than 30% in respect to Ti bare substrate. • HiPIMS and bias (−60 V) enhance the mechanical properties (H/E≈0.06; H 3 /E 2 ≈0.016) • A passivation layer of TiO 2 , Nb 2 O 5 and ZrO 2 serves to improve the corrosion resistance. This work presents the surface modification of commercially pure Ti specimens (c.p.-Ti) prepared by conventional powder metallurgy by depositing a thin film of a ß-Ti alloy (Ti-35Nb-7Zr-5Ta, wt. %, TNZT). Two types of pulsed technologies: conventional (p-DC) and high-power impulse magnetron sputtering (HiPIMS), with and without bias assistance (−60 V) under similar power conditions (250 W) were applied on titanium specimens and silicon substrates leading to different film morphologies and functional properties. Microstructural, X-ray diffraction, nanoindentation, surface wetting, XPS and electrochemical impedance measurements were done to characterize their functionality. All the coatings presented a reduced Young’s Modulus (E ≤ 80GPa) compared to the bulk Ti, representing a reduction of more than 30 %. This decrease can significantly contribute to the reduction of the stress-shielding effect, mitigating the risk of implant loosening and failure. The hardness values of TNZT coatings, slightly lower than c.p.-Ti substrate, range from 4.1 to 4.7 GPa. XPS analysis shows a passivation layer of TiO 2 , Nb 2 O 5 , and ZrO 2 , which offers high impedance and excellent corrosion resistance. The best compromise between mechanical and corrosion properties is achieved with the HiPIMS technology, thanks to its compact film microstructure with high electrical resistance, despite its limited thickness of about 1 μm.