Enhancing fretting corrosion resistance of micro-arc oxidation coating with Y2O3 nanoparticles on biomedical Ti6Al4V alloy for hip implants

Abstract

In this study, MAO coatings were fabricated on biomedical Ti6Al4V alloy by incorporating varying concentrations of Y₂O₃ nanoparticles into MAO electrolyte. The growth characteristics, microstructure, and mechanical properties of the coatings were then analyzed in detail. Fretting corrosion experiments were subsequently conducted under conditions simulating the actual head-neck interface of artificial hip joints. The influence of Y₂O₃ nanoparticle additives on the coatings' fretting corrosion performance was comprehensively evaluated. The results showed that the incorporation of Y₂O₃ increased both the transient processing voltage and the Zeta potential of the electrolyte, thereby accelerating coating growth. Y₂O₃ (4 g/L, 8 g/L) markedly enhanced the density, uniformity, and thickness of the coating, resulting in improved microstructural characteristics. Additionally, Y₂O₃ (4 g/L, 8 g/L) significantly improved the mechanical properties of the coating, including hardness, elastic modulus, and adhesion strength. Moreover, Y₂O₃ (4 g/L, 8 g/L) substantially decreased the friction coefficient, frictional energy dissipation, fretting corrosion volume, and corrosion current, thereby significantly enhancing the coating's resistance to fretting corrosion. Compared with the substrate and coatings without Y₂O₃, the Y₂O₃-coatings (8 g/L) improved fretting corrosion resistance by factors of 10.7 and 4.7, respectively. Notably, after the addition of Y₂O₃ (8 g/L), the dominant fretting damage mechanism transitioned from fatigue and adhesive wear to scratching and minor deformation. The findings of this study lay a valuable foundation for the optimization of MAO coatings and the protection of the head-neck interface in artificial hip joints.