Tantalum/Tantalum Oxide Coatings for Cardiovascular Stents: Enhancing Mechanical Performance, Corrosion Resistance, and Hemocompatibility

This study delivers a comprehensive evaluation of tantalum-based coatings designed as protective surface layers for cardiovascular stents, focusing on their mechanical durability, corrosion resistance, and surface properties relevant to hemocompatibility. Coatings consisting of tantalum (Ta), tantalum oxide (Ta2O5), and a bilayer Ta/Ta2O5 system were deposited onto 316L stainless steel using plasma-assisted reactive magnetron sputtering. Structural characterization confirmed a nanocrystalline β-phase for Ta, while Ta2O5 exhibited an amorphous, dense, grain-boundary-free morphology that provided superior crack resistance together with enhanced corrosion protection. The bilayer configuration demonstrated the highest overall performance by combining the hardness and mechanical support of Ta with the chemical inertness and stability of Ta2O5. This architecture achieved the greatest hardness (861.5 HV), improved toughness proxies expressed as H/E = 0.08 and H3/E2 = 0.06 GPa, and a favorable modulus gradient that effectively reduced interfacial stress and increased adhesion. Electrochemical testing in Hanks’ Body Fluid showed a dramatic 1000-fold reduction in corrosion current when compared with uncoated stainless steel, surpassing the performance of both individual monolayers. Assessments of surface properties further demonstrated that hydrophilic, oxide-rich surfaces limited protein adsorption and platelet activation, with Ta2O5 and Ta/Ta2O5 coatings performing strongly. Overall, these findings indicate that Ta/Ta2O5 bilayers provide a multifunctional surface solution for next-generation stents.