Effects of electrochemical polishing on the surface properties of laser-cut Ni–Ti alloy cardiovascular stents

Abstract

The Ni–Ti alloy, known for its shape memory effect, superelasticity, and remarkable biocompatibility, has emerged as a promising biomedical material. Its favourable surface properties have resulted in the requirements for its usage growing significantly, including in applications with small structures and complex geometries such as cardiovascular stents. Compared to sandblasting, grinding, and other surface treatment methods for such complex applications, electrochemical polishing offers the advantages of non-contact processing and uniform treatment; consequently, it has become a key surface treatment technique for cardiovascular stents. To further clarify the overall influence of electrochemical polishing on the service performance of cardiovascular stents, this study investigates the effects of electrochemical polishing parameters, such as the current density, electrode spacing, polishing temperature, and polishing time, on the surface performance of Ni–Ti alloy cardiovascular stents. This was achieved through orthogonal and one-factor experiments conducted on a custom-built cardiovascular stent polishing platform, with the goal of identifying the optimal process parameters. The results reveal that electrochemical polishing effectively reduces the surface roughness of the stent, eliminates defects such as thermal damage remaining after laser cutting, and improves the surface quality. Additionally, the oxide film formed on the surface after polishing enhances the corrosion resistance and prevents Ni ion precipitation. Overall, these findings provide a valuable reference for improving the serviceability and biocompatibility of Ni–Ti alloy cardiovascular stents.