Electrochemical and localized corrosion characteristics of kolsterised and DLC-coated 316LVM stainless steel for biomedical applications

This study examines the effects of various surface treatments such as solution annealing, nitric acid passivation, kolsterising, and diamond-like carbon (DLC) coating on the corrosion resistance of 316LVM austenitic stainless steel in simulated body fluid (SBF) environment, focusing on biomedical applications. Electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis, and microcapillary techniques were used to evaluate passive layer stability and barrier properties. Results show that solution annealing and nitric acid passivation enhance chromium-rich oxide formation, yielding a more stable passive layer, while kolsterising reduces passive layer integrity leading to severe crevice corrosion attack. Although DLC coating effectively eliminated crevice corrosion occurrence, it exhibited highly localized pitting at defective sites.