Investigating surface integrity, corrosion resistance and biocompatibility of 316L steel using carbon nanotube-assisted EDM process

Abstract

316L steel employed in biomedical applications has experienced mechanical failure triggered by insufficient biological reactions, a high corrosion rate, and surface impurities. Furthermore, the attenuated surface induced by corrosion and wear releases toxic elements, causing inflammatory effects. The prime aim of this research is to evaluate the carbon nanotube (CNT) based coating for enhancing surface integrity, corrosion resistance, and biological responses. This research also aims to comprehend the relationship between electric discharge machining (EDM) process variables and material properties. Several characterisation techniques, including scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), atomic force microscope (AFM), electron dispersive X-ray (EDX), MTT assays, powder X-ray diffraction (XRD) and potentiodynamic polarisation are utilised. The addition of CNT forms a nanoporous and thin coating of 10.3 μm, resulting in a crack-free surface with an adhesion strength of 23.77 MPa. A low corrosion rate (0.0012 mm/year) and almost 85 % of alive cells are observed on the coated surface of 316L steel. This research shows a method to form carbide and oxide-based coating for biomedical applications.