Human Blood Investigation of Ta-Coated 316L Stainless Steel to Evaluate Corrosion and Wear Behaviour Against Other Artificial Fluids for Orthopaedic Implants

Abstract

Stainless steel (316L) is widely used in biomedical applications, but concerns persist regarding its long-term surface properties, particularly in varying patient environments over time. This study aims to enhance the surface properties of 316L stainless steel through a 1.504 μm tantalum (Ta) coating applied via DC magnetron sputtering. The corrosion and wear behaviours were evaluated in different mediums, including human blood (HB), artificial saliva (AS), Ringer's solution (RS), and simulated body fluid (SBF). The Ta-coated 316L SS exhibited a shift toward nobler corrosion behaviour, with a corrosion rate of 0.146 × 10−2 mm/year in human blood, compared to the uncoated 316L SS, which showed corrosion rates of 0.325, 0.556, 0.779, and 1.425 × 10−2 mm/year in HB, RS, AS, and SBF, respectively. Electrochemical impedance spectroscopy (EIS) results indicated higher corrosion resistance of Ta-coated 316L SS in human blood than in other fluids. Potentiodynamic polarisation (PDP) results reveal that corrosion rate and current increased as the fluid environment shifted from human blood to simulated body fluid. Wear tests further demonstrated the superior wear resistance of the Ta-coated 316L SS, with a minimum wear rate of 0.086 × 10−5 mm³/Nm, compared to the uncoated 316L SS, which exhibited a maximum wear rate of 0.25 × 10−5 mm³/Nm. The microstructural analysis confirmed significant improvements in the surface properties of Ta-coated 316L SS, particularly in the human blood environment.