Formation of interlayer during cyclic wear process between pure titanium with hydroxiapatite by mechano-chemical interactive migration

Abstract

The estimation of nanoscale wear is crucial for comprehending the failure mechanisms of mechanical components, particularly in biomedical applications where wear-induced damage at the implant interface can result in aseptic loosening and failure. Although recent wear models effectively estimate wear coefficients, they exhibit limitations in accounting for the inelastic deformation and diffusion at the interlayer. A comprehensive understanding of interlayer formation and its impact is essential for elucidating the interplay between the mechanical and chemical effects in fretting wear behavior, which is vital for enhancing the longevity of mechanical components and implants. This study aims to examine the cyclic wear behavior of Ti in contact with a HAp surface under normal load by integrating mechanical and chemical influences. Three loading cycles, including the approach-retraction process of Ti spheres on the HAp surface, were simulated using Molecular Dynamics (MD) simulations with a reactive force field and the charge equilibrium method. The predominance of charge migration and the interactive effects of mechanical diffusion and charge migration on the local wear behavior were examined by analyzing the influence of temperature and charge variation on the Ti wear rate. Heterogeneous cyclic wear behavior was observed, with severe wear activation during contact formation followed by reduced wear owing to the charged Ti interlayer. This finding underscores the role of the interlayer in enhancing the wear resistance, emphasizing the necessity of incorporating surface chemistry and mechanical deformation in predictive wear modeling.