Electrochemical Characterization of AlTiN Coating on Stainless Steel Substrate for Biomedical Implant

Physical Vapor Deposition technology is an established technique to deposit metallic and ceramic coatings on different metallic substrates. Lateral Arc Rotating Cathode (LARC) technology has an added advantages of better mechanical uniform coating, consistent erosion of the electrodes and greater degree of ionization. LARC technology was used to deposit AlTiN coating on stainless steel SS 316L samples. The electrochemical behavior of the coating and the substrate was investigated using Electrochemical Impedance Spectroscopy (EIS) technique. Ringer Lectate solution was used as a simulated body fluid at 35 ± 2oC. The coating and substrate were characterized by Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDX) and Surface Profilometry. The Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy analysis revealed a consistent coating as a whole. The surface profilometry showed lower surface roughness after the coating. The Electrochemical Impedance Spectroscopy tests indicated that corrosion resistance of the coated sample was better, than the uncoated substrate in the electrolyte solution for short duration (one day) and behaved like cathodically protected coating and showed more resistivity. However, the Electrochemical Impedance Spectroscopy results varied because of the penetration of chlorite ions through the porosity in th coating and reaction with the coating material after the prolonged insertion.