Improving the adhesive, mechanical, tribological properties and corrosion resistance of reactive sputtered tantalum oxide coating on Ti6Al4V alloy via introducing multiple interlayers

Tantalum oxide film has become an investigation focus for surface modification materials in the biomedical field owing to its outstanding biocompatibility, anti-corrosion, and anti-wear performances. However, tantalum oxide films exhibit poor adhesion because of the mismatch between the properties of the film and the substrate. In this study, a novel multilayer tantalum oxide coating of TamOn/TamOn-TiO2/TiO2/Ti (code M-TamOn) was deposited on Ti6Al4V by magnetron sputtering with TamOn single-layer coating as control. The purpose of this work is to evaluate the influence of the introduced TamOn-TiO2/TiO2/Ti multi-interlayer on the microstructure, adhesive, mechanical, and anti-corrosion properties of reactive sputtered tantalum oxide coatings. The outcomes show that the TamOn-TiO2/TiO2/Ti intermediate layer improves the bonding strength between the TamOn layer and Ti6Al4V matrix from 17.83 N to over 50 N and enables the TamOn coating to have an increased H/E and H3/E2 ratio, decreased friction coefficient and wear rate, raised potential, and reduced corrosion current density. The improved properties of the multilayer system are attributed to the positive effects of the inserted multiple interlayers in reducing the residual stress in the coating, coupling the mechanical performance between the layer and the substrate, blocking the continuous growth of penetrating defects in a film with columnar structure. These experimental results provide a workable route for improving the properties of the tantalum oxide coating on Ti6Al4V alloy for medical applications.